Post by: Douglas Anderson on December 23, 2007, 04:51:50 PM
There is so much wealth of knowledge on here it is amazing. I don't think there is another site like this on Earth. If there are other intelligent beings out there I'm sure they must be as fanatical about there music as we are.
Anyway I'm trying to put together a sound system but I'm not as upto-date with the loudspeaker side of things like I used to be. I pretty much have the analog processors that I need (welcome opinions on the digital all-in-ones such as the DBXs). I have amps (QSC and CROWN). Not much has changed in the AMP business, QSC, CROWN, and CREST still run things (right?)!
I've used JBL 2445J/2380 for tops, EV DL 12x or EV 12L Pro Line for mids, and JBL 2225H, EV 18B Pro Line, and EV EVX 180 for bass/sub woofers in the past. In trying to put together a 3-way system what would you guys (and maybe a few ladies) recommend for Horn/Drivers, midrange/mid bass, and bass/sub woofers?
I've always preferred constructing cabinets as opposed to buying ready made-ready loaded. I'll be playing Reggae, R&B, Soul, Pop, and Country music (mostly indoors but occasionally outdoors)so I have no real preference as far as whether they are more suited for reflex, horn-loaded, or combination cabinets.
If anyone have or know anyone with detailed cabinet plans for the EV SH1810L-ER reverse sub scoop cabinet please get in touch with me.
Post by: peter.golde on December 23, 2007, 04:55:43 PM
http://www.speakerplans.com/forum/
Also in the archives on the EV website they have plans for most of their old TL reflex cabs and horn loaded bass.
http://archives.telex.com/archives/EV/Builders%20Plans/
Post by: Douglas Anderson on December 23, 2007, 09:12:55 PM
He seems to have gotten real famous in the biz. Goes by the name of "SHORTMAN".
Post by: Greg Cameron on December 23, 2007, 10:02:35 PM
| Douglas Anderson wrote on Sun, 23 December 2007 13:51 |
I've always preferred constructing cabinets as opposed to buying ready made-ready loaded. I'll be playing Reggae, R&B, Soul, Pop, and Country music (mostly indoors but occasionally outdoors)so I have no real preference as far as whether they are more suited for reflex, horn-loaded, or combination cabinets. |
Unless you're hellbent on building your own boxes, you might want to reconsider. Things in general have improved immensely with off the shelf boxes compared to the late 80's/early 90's. For what it will cost you in time and materials to build you own boxes, you can usually get good to excellent performing boxes at many levels. This was not the case back in '89 where choices were limited and so was quality. Virtually every aspect of speaker design has improved including box design, materials, drivers, horns, amplification and processing. Even some of the small plastic boxes can run circles around the larger clunky boxes of the 80's in overall performance and value. I'd highly recommend throwing out some info as to the size of rooms and crowds you plan on covering and solicit some advice on what might work and what other people are using. Of course, an idea on budget is always helpful...
Greg
Edit: SP
Post by: Douglas Anderson on December 24, 2007, 04:14:10 PM
| Greg Cameron wrote on Sun, 23 December 2007 22:02 | ||
Unless you're hellbent on building your own boxes, you might want to reconsider. Things in general have improved immensely with off the shelf boxes compared to the late 80's/early 90's. For what it will cost you in time and materials to build you own boxes, you can usually get good to excellent performing boxes at many levels. This was not the case back in '89 where choices were limited and so was quality. Virtually every aspect of speaker design has improved including box design, materials, drivers, horns, amplification and processing. Even some of the small plastic boxes can run circles around the larger clunky boxes of the 80's in overall performance and value. I'd highly recommend throwing out some info as to the size of rooms and crowds you plan on covering and solicit some advice on what might work and what other people are using. Of course, an idea on budget is always helpful... Greg Edit: SP |
I'll be playing mostly Reggae and R&B so that chest thumping bass in the 50 - 100 hz range is required. I already have couple double 18 vented cabinets with 600 watt JBL speakers so I guess I'll probably need to go with some kind of bent/folded horn or scoop design to carry the sound to a audience of say 300 people in a nice size hall (or outdoors).
As for budget, I'd say I'm willing to spend around $275 for each raw bass/sub speaker. They'd be powered by QSC RMX line amps (1850HD, 2450, and 4050HD).
Have anyone on this side of the waters (US) heard of PRECISION DEVICES (PD), 18 Sound, and B&C speakers? They seem to be very popular in England where the people are fanatics about designing and building their own cabinets. What do you guys think about Eminence, RCF, and Celestions?
Post by: Tate_Tullis on December 24, 2007, 08:49:36 PM
| Douglas Anderson wrote on Mon, 24 December 2007 15:14 | ||||
I'll be playing mostly Reggae and R&B so that chest thumping bass in the 50 - 100 hz range is required. I already have couple double 18 vented cabinets with 600 watt JBL speakers so I guess I'll probably need to go with some kind of bent/folded horn or scoop design to carry the sound to a audience of say 300 people in a nice size hall (or outdoors). As for budget, I'd say I'm willing to spend around $275 for each raw bass/sub speaker. They'd be powered by QSC RMX line amps (1850HD, 2450, and 4050HD). Have anyone on this side of the waters (US) heard of PRECISION DEVICES (PD), 18 Sound, and B&C speakers? They seem to be very popular in England where the people are fanatics about designing and building their own cabinets. What do you guys think about Eminence, RCF, and Celestions? |
ive been impressed with those three. Their good choice's in my book.
Post by: Bennett Prescott on December 24, 2007, 09:08:44 PM
Post by: SteveKirby on December 25, 2007, 02:27:15 PM
RCF/18Sound/B&C/Beyma are all very popular drivers with folks who build the pro level cabs.
I still think that you can save a few bucks building cabs, but you can't factor in your engineering time, or it is definitely a losing proposition. And in a lot of cases, you can't match the engineering resources of a big company.
You probably don't have the test facilities, equipment, or the time and money to try 10 different drivers in each bandpass. Most home builders have to research the best they can, buy the parts and hope for the best. If drivers sounded exactly like their specs, this might be fine, but they don't, so success is often a matter of luck.
Post by: Bob Leonard on December 25, 2007, 06:28:52 PM
| SteveKirby wrote on Tue, 25 December 2007 14:27 |
Check out my thread about replacing EVM Pro Lines and DL18MT's with 18Sound drivers. Absolutely no comparison. While there are some great classic drivers out there from EV and JBL, the improvement in understanding of motor structures, cone materials and manufacturing techniques has made those classics not worth the trouble any more. They are limited in power handling and sound quality compared to modern drivers. RCF/18Sound/B&C/Beyma are all very popular drivers with folks who build the pro level cabs. I still think that you can save a few bucks building cabs, but you can't factor in your engineering time, or it is definitely a losing proposition. And in a lot of cases, you can't match the engineering resources of a big company. You probably don't have the test facilities, equipment, or the time and money to try 10 different drivers in each bandpass. Most home builders have to research the best they can, buy the parts and hope for the best. If drivers sounded exactly like their specs, this might be fine, but they don't, so success is often a matter of luck. |
Steve,
You can't be serious with the above statement concerning EV and JBL. It was JBL that led the way with Neo, dual voice coils and heat dissipation, and EV still has very respectable products in this line of drivers.
Doug,
After a near 6 month period of testing and research while I looked for 18" drivers it came down to three (3) manufacturers whose drivers met my criteria. They were 18 Sound, B&C, and JBL. I had the chance to audition and listen to each driver I was interested in. My final choice was between B&C and JBL.
The two speakers were the JBL 2242H and the B&C 18TBX100. If I had set a particular price range then I would have chosen the B&C. Since I was not restricted by budget my choice was the JBL 2242H. Links to both are below.
The RCF drivers were taken off of the list quickly after a discussion with a distributor who had dropped the line due to massive problems with the line. Mostly with structural failures such as magnets breaking off of the spiders, etc.. The Beyma was a good choice, Celestion not even close, Eminence was not a contender.
The B&C drivers are within your budget. I suggest you take a good look at that manufacturer. I fully agree with Bennett on this subject. Good luck!
http://www.bcspeakers.com/index.php?sez=1&categoria=1&am p;id_descrizione=2&prodotto=15
http://www.jblpro.com/pages/pub/components/2242.pdf
Post by: SteveKirby on December 25, 2007, 07:23:44 PM
I would definitely put a 2242 or modern EVX up against a B&C or 18Sound. At that level, it's about variations in performance and cost (the EV and JBL having a cost premium which is probably warrented by being the top of the class in performance) Any of these would wipe out an EVM or D130.
Post by: Tim Duffin on December 25, 2007, 07:25:29 PM
should be followed with: "By speaker manufacturers who cannot afford the newer advances offered by JBL or EV...or wish not to pay for advanced technology and would rather settle for aged technologies at a lower price point."
Fact is, while the companies you mentioned are 'good', they are not the best-- the best comes with a higher price which is out of reach of most consumers. No 18" driver from any manufacturer compares to the JBL 2269, now you decide why.
T
Post by: Chris Van Duker on December 25, 2007, 08:09:26 PM
As for the 18" drivers which you can buy, between the JBL 2242 and the B&C 18TBX100, I like them both, but my vote is for the B&C -- close to the same performance for about half the price, and much cheaper to recone as well (though I haven't needed to do that yet).
Unless you really need to save 8-10lbs by going to a neo magnet, the 18TBX100 is pretty close to state-of-the-art. It's a very nice sounding, low distortion driver which also happens to be damn near bulletproof. They're as popular as they are for a good reason.
A couple people on here also recommended Peavey LoRider 18's, which are about $100 cheaper. I've used them, and like them, but for the price difference I'd probably still rather have the B&C's.
It wouldn't hurt to check out the other Italian manufacturers, either: 18sound, RCF (L18P300 is past its prime, though), Ciare. And moving north to Germany, BMS is known for their compression drivers but a number of their woofers look pretty interesting, too.
-Chris
Post by: Bob Leonard on December 25, 2007, 10:08:45 PM
The 2K+ price tag for the 2269 is the list price for the driver if purchased from parts. Because those drivers are used in current production boxes (Vertec), they are not available for purchase as a seperate component, same as the 2268 used in the SRX line.
The 2242 and the 2241, used in the Cinema products are available. The cost of the 2242H, the driver I use in my boxes is around $650.
Steve,
I see your point however your comment doesn't quite come across in that manner. Sorry if I misunderstood.
Post by: Elliot Thompson on December 26, 2007, 04:04:48 AM
| Douglas Anderson wrote on Mon, 24 December 2007 21:14 |
Have anyone on this side of the waters (US) heard of PRECISION DEVICES (PD), 18 Sound, and B&C speakers? They seem to be very popular in England where the people are fanatics about designing and building their own cabinets. What do you guys think about Eminence, RCF, and Celestions? |
Hello Douglas.
I've gone through most of the brands you are eying years ago.
Precision Devices. The price it would cost you to import them from the UK to the States, you could find a better speaker within that price point (Speaker + Shipping).
18 Sound. This company developed when RCF stopped offering their raw woofers to the public and, solely devoted their services to EAW/Mackie. A very good brand. If I remember correctly, some of the early designers of RCF are now there.
B&C. They became popular when RCF stopped offering speakers to companies like Yorkville and such. It was the closest alternative available at the time. And it's because of that, their popularity grew.
RCF. This was EAW's main source for drivers decades ago. They focus on reflex/sealed speakers with very few horn-loaded drivers for bass applications. These drivers were running neck and neck with Electrovoice & JBL in the late 80's to early 90's.
Eminence. They focus primarily on reflex/sealed type drivers. So, you are very limited if you choose not to use their drivers in a conventional enclosure.
Celestion. They are no longer the UK company you probably are fond of. They are now part of a company in China and are changing their whole line of woofers based on that merger. The majority of their older woofers are designed for horn-loaded cabinets with very minimum for reflex/sealed enclosures.
The Eighteen Sound 18 LW 1400 is what you are looking for. It is a middle of the road driver so it works well not only in horn boxes but reflex cabinets as well. It also offers the same xmax from drivers costing two, three times the amount.
Best Regards,
Post by: Douglas Anderson on December 26, 2007, 05:45:51 AM
Post by: Douglas Anderson on December 26, 2007, 06:32:35 AM
Hello Douglas.
I've gone through most of the brands you are eying years ago.
Precision Devices. The price it would cost you to import them from the UK to the States, you could find a better speaker within that price point (Speaker + Shipping).
18 Sound. This company developed when RCF stopped offering their raw woofers to the public and, solely devoted their services to EAW/Mackie. A very good brand. If I remember correctly, some of the early designers of RCF are now there.
B&C. They became popular when RCF stopped offering speakers to companies like Yorkville and such. It was the closest alternative available at the time. And it's because of that, their popularity grew.
RCF. This was EAW's main source for drivers decades ago. They focus on reflex/sealed speakers with very few horn-loaded drivers for bass applications. These drivers were running neck and neck with Electrovoice & JBL in the late 80's to early 90's.
Eminence. They focus primarily on reflex/sealed type drivers. So, you are very limited if you choose not to use their drivers in a conventional enclosure.
Celestion. They are no longer the UK company you probably are fond of. They are now part of a company in China and are changing their whole line of woofers based on that merger. The majority of their older woofers are designed for horn-loaded cabinets with very minimum for reflex/sealed enclosures.
The Eighteen Sound 18 LW 1400 is what you are looking for. It is a middle of the road driver so it works well not only in horn boxes but reflex cabinets as well. It also offers the same xmax from drivers costing two, three times the amount.
Best Regards, [/quote]
Thanks for the info Elliott. As far as price it looks like its between the B&C and the 18 Sound. There is a popular Pro Audio store in New York (unsure of forum rules so left unnamed) who sells 12 different 18" speakers. They rated there top 7 best sellers as:
1. Eminence Kilomax Pro-18A
2. Selenium 18WS600
3. 18 Sound 18LW1400
4. Eminence Omega Pro-18A
5. Peavey 18 LOW MAX
6. RCF L18P300
7. Eminence Sigma PRO-18A-2
The B&C 18TBX100 which is also sold there was unrated along with 4 other speakers (B&C, Peavey, RCF, Selenium).
Anyone familiar with the Selenium?
I checked out another speaker site who I believe is based in Illinois or Michigan and of all the various brands that they sell the only two that were out of stock were from the Fane Colossus series? Have they been discontinued or are they that popular?
One last thing, I notice these new speakers have ridiculous power handling capabilities, 1500w, 2400 watts. Back in the day 8 ohm speakers were the standard and ratings were 400w - 600w. In order to power these monsters is 4 ohm speakers more suitable than buying the 8 ohm versions? Are there any drawbacks to using 4 ohm speakers besides reaching the amplifier 2 ophm limits quicker when used in multiples?
Post by: Elliot Thompson on December 26, 2007, 08:10:44 AM
You need to decide what you are trying to accomplish here and, not worry about who's the top rated driver. Those ratings could be based on anything which more than likely has nothing to do with the box you are using in question.
There are certain principals in which you need to abide to achieve the sound you are aiming for. With that being said, I recommended the 18 Sound because you mentioned a Scoop which I assumed you were planning to house the woofer in. If you are looking at some other design, then you need to tell us what kind of design is it to find the best suited driver for the cabinet in question.
Bare in mind, old outdated boxes pretty much required certain drivers to deliver optimum performance. This applies to all boxes btw. Once you put a driver that does not meet the cabinets criteria, you will almost always achieve unsatisfied results.
Out of your list (Providing we are talking about old 18 inch Scoops) you could look at Eminence Omega and Sigma at that's pretty much it. Although, the 18 Sound 18 LW 1400 would still be your best choice.
The wattage increase is a matter of marketing today versus yesterday. Since everyone is yearning for higher wattage woofers they are rated less conservative today than yesterday. So the older drivers could indeed handle more power. Providing you are not overdriving the amplifier in the process.
There is a science behind amplifier-loudspeaker integration. If you are the type that must clip your amps just for the sake of clipping them, you will find yourself reconing woofers often. If you have ample amount of SPL (which comes from using multiple subs), you'll find yourself not even thinking about overdriving your woofers to the point of extinction.
As four 4 ohm woofers. They are pretty popular in home/car audio scene where you want to get the most power out of a single driver. In the sound reinforcement business more is always better considering we are not providing sound in a living room much less a backseat of a car.
Best Regards,
Post by: Bob Leonard on December 26, 2007, 09:57:29 AM
| Douglas Anderson wrote on Wed, 26 December 2007 05:45 |
Thanks for the info Bob. I have a brother in CT who is also looking for speakers. I was wondering where were you able to listen to the B&C speakers? If it's not too far from New Haven maybe he can take a drive and take a listen for himself!! |
Douglas,
There was a local band using the B&C as replacements in the cabinets they were using that I had listened to. For your's and your brothers purposes I would contact Charlie Tappa of Pro Sound Service located in Braintree, MA. Charlie is by far the largest distributor of B&C and JBL that I am aware of. He keeps tons of the product in stock, has great prices, and if you talk with him he'll take the box you're planning on using and spec. out the correct driver for you. I am no longer an Eminence fan. I have a number of their 18s in the basement all packaged nicely for use as spares if ever needed, but never really liked the tone/sound from their 18s. One point I'll make is that Neo drivers need to be well cooled. Excessive heat will suck the life from a Neo driver, demagnitizing the motor assembly. Be sure you meet the mfg. specs for cooling, especially the clearence needed behind the speaker as Neo speakers tend to be longer/deeper than non-Neo speakers. Good luck with your search.
Post by: Bennett Prescott on December 26, 2007, 01:39:07 PM
| Elliot Thompson wrote on Wed, 26 December 2007 08:10 |
The wattage increase is a matter of marketing today versus yesterday. Since everyone is yearning for higher wattage woofers they are rated less conservative today than yesterday. So the older drivers could indeed handle more power. Providing you are not overdriving the amplifier in the process. |
I'm sure there have been no technological advances allowing higher heat dissipation in the interim.
Two drivers with equal T/S parameters and equal sensitivity in the same box, the one with the higher power handling will have a higher max output. That doesn't mean "it needs more power", it means you can GIVE it more power, though.
Post by: Ivan Beaver on December 26, 2007, 02:29:53 PM
Two drivers with equal T/S parameters and equal sensitivity in the same box, the one with the higher power handling will have a higher max output. That doesn't mean "it needs more power", it means you can GIVE it more power, though.[/quote]
It never ceases to amaze me the number of people who will not buy a particular product because it can handle more power. They say they can't afford an amp that size and therefore want to go with a lower power rated product, because they can afford an amp for that loudspeaker. So if it was simply rated lower, then they would but it
Sensitivity (or any other spec) NEVER enters into their thinking.
Post by: Elliot Thompson on December 26, 2007, 11:43:06 PM
| Bennett Prescott wrote on Wed, 26 December 2007 18:39 | ||
I'm sure there have been no technological advances allowing higher heat dissipation in the interim. Two drivers with equal T/S parameters and equal sensitivity in the same box, the one with the higher power handling will have a higher max output. That doesn't mean "it needs more power", it means you can GIVE it more power, though. |
This depends more on how the manufacture measured the driver in question. Some companies use mathematical measurements whereas others take into consideration distortion as far as xmax/xmech is concerned. Since we are talking woofers from all parts of the world, it is not as easy to compare one against the other even though they offer similar specs. It's very hard to find two drivers from different companies with the exact TS Parameters. Drivers in Europe tend to focus more on horn-loaded drivers whereas the States focus on Reflex/Sealed transducers. Personally, I look at the no% and disregard what the input sensitivity spec states for the no% is the true sensitivity of the driver regardless what the 1 watt/2.83 volt says. We must also keep in mind that no matter how loud a driver is, if it is not loud at the desired frequency, the woofer is useless for the application.
Best Regards,
Post by: Iain_Macdonald on December 27, 2007, 09:02:11 AM
Just to add a few points to Elliot's excellent post.
PD: Nice drivers with a reputation for reliability and the capability to take abuse. Their last designer Neville has left to join Celestion. PD are owned by the European importers of Eminence. They also own the recently revitalised Fane. Friends in the USA have often complained of high pricing for small orders. This is usually resolved by speaking direct to the factory in the UK.
CELESTION: Beginning to make waves in the OEM market. They now have a very experienced R&D team. Expect to see some interesting new product in the next year. Not all the current product is on the web site.
18Sound: Nice drivers with great consistency. Part of AEB Group.
http://tinyurl.com/23vdxc
Seasons Greetings.
Iain.
Post by: Iain_Macdonald on December 27, 2007, 09:16:59 AM
| Tim Duffin wrote on Wed, 26 December 2007 00:25 |
RCF/18Sound/B&C/Beyma are all very popular drivers with folks who build the pro level cabs should be followed with: "By speaker manufacturers who cannot afford the newer advances offered by JBL or EV...or wish not to pay for advanced technology and would rather settle for aged technologies at a lower price point." Fact is, while the companies you mentioned are 'good', they are not the best-- the best comes with a higher price which is out of reach of most consumers. No 18" driver from any manufacturer compares to the JBL 2269, now you decide why. T |
Ummmm..... Not quite. In fact a gross insult to many/most pro level manufacturers/box stuffers. JBL and EV have mostly withdrawn from the OEM market. So their technology is not available to the rest of the market. You also make the incorrect assumption, that there isn't a better 18" driver than the 2269. There are a number of better drivers available to manufacturers.
So what defines the best 18" driver?
Iain.
Post by: Adam Kane on December 27, 2007, 06:07:33 PM
Seriously though...I hate arguing about "the best driver" without taking application (musical genre, enclosure, required output level, etc) into consideration. It's absolutely pointless.
Sure, the 2269 is an excellent driver capable of sounding super dooper. But, what if the application is an enclosure which calls for a driver with completely different t/s parameters? Now the 2269 is no longer the best driver for YOU. Maybe the driver of choice is the Eminence/B&C/18Sound/whatever. Before I get flamed...I'm in no way dissing JBL or EV. Just saying that depending on the application, there may be a better driver out there regardless of price.
Maybe I belong to a lucky minority, but my company and I get to pick gear based on what SOUNDS good, not what happens to be made by brand X. And hey...once in a while you're pleasantly surprised to find that the better sounding piece is the less expensive option.
Post by: Bob Leonard on December 27, 2007, 10:00:31 PM
From JBL;
"In VGC, air is drawn in directly from the outside
through three openings in the back of the magnet
structure. Air drawn into the structure passes over and
around the voice coil; it is exhausted immediately on the
reverse movement of the voice coil.
With VGC, JBL was able to make significant
reductions in the amount of dynamic compression in
transducers operated near their upper power limits. Here,
the effect of rapid and efficient removal of heat enables
the VGC transducers to reach final thermal equilibrium
with less residual power compression than traditional
designs, and long term improvements of 3 to 4 dB can be
made. JBL's Technical Notes Volume 1, Number 18
presents more information on VGC.
Post by: Scott Smith on December 28, 2007, 07:47:46 AM
Post by: Elliot Thompson on December 28, 2007, 10:12:55 AM
The power compression of the 2242 (- 3.3 dB @ 800 watts) falls in the same class as many other woofers in it's league. The VGC (Vented Gap Cooling) has been around ever since the days Eletrovoice was producing the EVM Series from the 70's.
All in all the 2242 is good for a very small compact box. However, when we are talking large sub chambers the 2242 will fall short of expectation.
Best Regards,
Post by: Tim Duffin on December 28, 2007, 03:25:47 PM
Now, you tell me which 18" driver specifically can exceed any specification of the JBL 2269 and provide data.
http://www.jblpro.com/vertec1/VT4880A%20Spec%20Sheet.pdf
T
Post by: Jeff Babcock on December 28, 2007, 03:57:57 PM
| Tim Duffin wrote on Fri, 28 December 2007 15:25 |
Best, meaning-- "exceeding all other manufacturers offerings in every specification relating to sub-bass frequencies." Were not talking about which woofer is "more musical" or any of the other BS that people come up with to defend their inferior products, were talking about the amount of air an 18" woofer can move without self-destructing and without the assistance of exotic horn loading. Now, you tell me which 18" driver specifically can exceed any specification of the JBL 2269 and provide data. http://www.jblpro.com/vertec1/VT4880A%20Spec%20Sheet.pdf T |
2269 does have impressive specs but at what point does cost become a factor?... not that I have anything against JBL but their driver pricing structure sometimes makes me scratch my head.... at $2000 list I'm sure there are other manufacturers capable of making comparable or potentially even better drivers, but they choose not to do so as the market would not support that decision.
Certainly you could say that the 2269 is the best driver for the VT4880 cab it is loaded into, as certainly it was designed specifically for that application. Placing it anywhere else will get less than "optimum" results in all probability. I'm sure it would still be great, but to call it the "best" is simply untrue unless "the best" has extremely limited criteria.
Calling horn loading "exotic"... are you serious? It's hardly a rare and mysterious process anymore and there are a number of stellar sounding horn loaded boxes that have stupid amounts of output. If you just want to talk about purely moving air I could find some horn loaded boxes from Danley or Bassmaxx that I would happily put up against 2269 front-loaded boxes anyday.
Post by: Adam Kane on December 28, 2007, 04:10:05 PM
Ok ok ok. I see. It's about "moving air" but not necessarily in a musical fashion.
I'm sure if I looked hard enough, I could find some crazy 18" car sub woofer with higher power handling and a 7" xmax. But odds are, it would sound like crap. Really loud crap. And be very limited in application.
But, I guess I have a lot to learn, Tim. Thanks for teaching me that any sub cabinet that doesn't employ the 2269 is not worth my time listening to.
btw...I didn't see any t/s parameters when I followed your link. I did see a peak excursion number that, while not meaningless, can be misleading if someone doesn't know the difference between that (xmech) and xmax. There's also sensitivity to take into account. What good is a speaker if you need to feed it twice as much power to get it half as loud? (not literally of course, but you get my point)
I've already spent far too much thinking about how to respond to you.
I'm done. Good day sir.
Post by: Tony "T" Tissot on December 28, 2007, 04:27:20 PM
Use ignore - or choose from one of the following responses:
1. "Duffin, you no good ..... ...." (apologies to Dan Ackroyd)
2. Did you get your "2 outlet" power combiner patented yet?
3. How does an 8 box JRX rig = "80,000 WATTS!"
Post by: Tim Duffin on December 28, 2007, 07:02:47 PM
| Tony "T" Tissot wrote on Fri, 28 December 2007 13:27 |
It's Duffin for crying out loud.. Use ignore - or choose from one of the following responses: 1. "Duffin, you no good ..... ...." (apologies to Dan Ackroyd) 2. Did you get your "2 outlet" power combiner patented yet? 3. How does an 8 box JRX rig = "80,000 WATTS!" |
Tony,
Why are you retarded? I was the person who advocated getting a power distro, not combining 2 outlets. Where did you ever get that idea from? Second, what JRX rig? Do you know how to read? I rent JRX speakers to dj's for house parties, school dances, small bars, etc-- that is not my rig. Where did you get this idea from?
Third-- and this is important. Do you have any scientific knowledge of sound whatsoever or are you just another one of those middle aged guys who took a class in junior college and thinks that they know everything about electronics and audio because of it? I have seen nothing that you have ever posted which amounted to more than a high school freshman level of audio knowledge.
If not, prove me wrong---right here, right now. I noticed that you are in Northern California, weelllllllll so am I. What is your next show, I would like to see just how awesome YOUR rig is!
T
Post by: Tim Duffin on December 28, 2007, 07:09:16 PM
T
Post by: Phil LaDue on December 28, 2007, 07:15:08 PM
I actually agree with Tim:
Jacob Gop had the "brilliant" two outlet idea.
(he's probably started an electrical fire by now)
I don't recall JRX being discussed.
There was one of those "JBL- Pro or not" arguments involving Mr. Duffin and IIRC Bob Leonard.
Mr. Duffin, you still have crap for credibility in the eyes of most people here but you were wrongly accused this time.
Post by: Ivan Beaver on December 28, 2007, 07:38:14 PM
As with any bass horn, you cannot just put a "better" driver in it and expect the performance to increase. Many people have ruined the sound of some old classic W cabinets by putting what they "thought" was a better driver in it and ended up with poorer performance.
The driver/horn match is very picky.
I remember years ago (before I knew anything) trying to convince a friend of mine that he needed to take out the cheap stamped Eminence drivers in his Peavey FH1 cabinets and replace them with (at the time) premium JBL 2225. There was no question on which was the "better" driver. But better for what?
When we tried it, the cabinet with the cheap driver easily outperformed the one with the premium JBL-it was louder and went lower. It was very eye opening to me. I had heard such things, but never experienced it.
Any evidence to back up your statements?
Post by: Iain_Macdonald on December 28, 2007, 07:40:11 PM
I see that other people have replied to you already. I am in agreement with the technical points they make. Doug made a good job of the drivers in this cabinet. I don't see any meaningful specs for the driver, so I won't address that issue. But the spec sheet raises the usual questions about sensitivity, and power handling, and measurement strategy. Don't misunderstand me, JBL make good product.
You asked for data on better drivers. Nobody is going to publish confidential OEM data in a forum, and neither am I. It would be thoroughly unprofessional. But let me tell you that there is a driver being offered right know, that has 140mm pk>pk xmax. Note that it is xmax, and not xmech. 6"voice coil and sensitivity about 94db. Tested at 3.5kw but looks as if it will do 4+. Ivan mentioned something from DSL that looks as if it might use a similar driver. Just to give you an idea of what is going on in the market. Take a look at the Acoupower web site. They are by no means the leader in this area. Do remember that they are not showing you OEM specs. Look at the videos, you should find them interesting.
http://www.acoupower.com/index.php
Best wishes.
Iain.
Post by: Iain_Macdonald on December 28, 2007, 07:52:37 PM
There are two ways to design a horn. a) Working from the driver specs and designing a cabinet b) Deciding on the physical spec for the cabinet and working back to get the driver specs. The T/S specs and general physical design for a horn driver are usually quite different to that of a vented cab. I would also point out, that in the real world, mfrs take in to account things like, practical size and weight, truck pack, and whether it can fit through a standard door. Using design method a) often results in an impractical design.
Best wishes,
Iain.
Post by: Tim Duffin on December 28, 2007, 08:50:37 PM
Have you ever heard one in real life in any circumstance?
T
Post by: Tim Duffin on December 28, 2007, 08:55:01 PM
T
Post by: Tony "T" Tissot on December 28, 2007, 09:16:30 PM
| Phil LaDue wrote on Fri, 28 December 2007 16:15 |
May the higher powers strike me down with lighting bolts! I actually agree with Tim: Jacob Gop had the "brilliant" two outlet idea. (he's probably started an electrical fire by now) I don't recall JRX being discussed. There was one of those "JBL- Pro or not" arguments involving Mr. Duffin and IIRC Bob Leonard. Mr. Duffin, you still have crap for credibility in the eyes of most people here but you were wrongly accused this time. |
I apologize for the incorrect reference to the cord.
- But Jacob Gop is/was as I recall Tim Duffin!
I should have referenced: "Chinese" wire, skin-effect, Milwaukee batteries, and that JBL didn't need processing, unlike EAW (with Gunness), Veterc V4 DSP notwithstanding.
And his rig is now only rated at 75,000 WATTS!
Post by: Iain_Macdonald on December 28, 2007, 09:22:28 PM
| Tim Duffin wrote on Sat, 29 December 2007 01:50 |
Whats this OEM data thing you are talking about? would that be the AES power rating? I want measured SPL with a meter in the "manufacturers recommended box" whatever that is -- I can tell from just looking at that acoupower driver that it trades efficiency and cone area for excursion capability, and even then, the excursion of that driver may not be linear at all. It is basically a recycled car audio design for High SPL only in enclosed areas...like a car. T |
| Tim Duffin also wrote on Sat, 29 December 2007 |
It is a demonstrated fact that the same horn design using a driver with higher BL than another driver performs at least as well if not better. The servodrive BT7 should be enough evidence of this fact for you-- the driver system in that device was created for max linear excursion with max force factor. If you invented another pistonic system with greater excursion but the same (or greater) force factor, your driver would perform better in that box, no question. |
Now I realise why people come down hard on you.
An old saying that is apposite: "Always keep your words soft and sweet, just in case you have to eat them."
Post by: Tim Duffin on December 28, 2007, 09:26:11 PM
| Tony "T" Tissot wrote on Fri, 28 December 2007 18:16 | ||
I apologize for the incorrect reference to the cord. - But Jacob Gop is/was as I recall Tim Duffin! I should have referenced: "Chinese" wire, skin-effect, Milwaukee batteries, and that JBL didn't need processing, unlike EAW (with Gunness), Veterc V4 DSP notwithstanding. And his rig is now only rated at 75,000 WATTS! |
Tony.
What are you talking about and who is Jacob Gop? Are you making the suggestion that I am posting under 2 different names? That is not true as I have never done that and I would like some third party to verify the IP addresses to be sure that YOU, Tony Tissot are LYING.
on a side note, guess I better watch those dang "Veterc" boxes, huh Tony! Im still waiting to see your rig.
T
Post by: Tim Duffin on December 28, 2007, 09:27:19 PM
T
Post by: Phil LaDue on December 28, 2007, 09:51:25 PM
| Tony "T" Tissot wrote on Fri, 28 December 2007 21:16 |
But Jacob Gop is/was as I recall Tim Duffin! |
What now?
As I recall Jacob was a 14 year old with a big mouth.
Post by: Iain_Macdonald on December 28, 2007, 09:51:47 PM
| Quote: |
Please explain what portion of that argument you feel is invalid. |
All of it. The acoupower was used as example of other mfrs having advanced technology. Not as an indication of state of the art. Please reread my post. Whatever else you may say about it, the acoupower is not a recycled car driver! Linearity is one of it's strengths and design objectives. OEM means Original Equipment Manufacturer. Product that is made solely for manufacturers. e.g. 18 Sound building drivers for EAW.
WRT the second quote box. I am sure Ivan will answer. But the idea of just changing the driver for one with more volume displacement is not as simple as it would appear. What about the throat dimensions and back chamber volume? You could easily end up with large amounts of distortion.
Best wishes.
Iain.
Post by: Tony "T" Tissot on December 28, 2007, 10:05:34 PM
| Phil LaDue wrote on Fri, 28 December 2007 18:51 | ||
What now? As I recall Jacob was a 14 year old with a big mouth. |
You're right. The resemblance is uncanny.
Post by: Tim Duffin on December 28, 2007, 10:21:58 PM
| Iain Macdonald wrote on Fri, 28 December 2007 18:51 | ||
All of it. The acoupower was used as example of other mfrs having advanced technology. Not as an indication of state of the art. Please reread my post. Whatever else you may say about it, the acoupower is not a recycled car driver! Linearity is one of it's strengths and design objectives. OEM means Original Equipment Manufacturer. Product that is made solely for manufacturers. e.g. 18 Sound building drivers for EAW. WRT the second quote box. I am sure Ivan will answer. But the idea of just changing the driver for one with more volume displacement is not as simple as it would appear. What about the throat dimensions and back chamber volume? You could easily end up with large amounts of distortion. Best wishes. Iain. |
How do you know for a fact that it is not a recycled car audio design? What about its efficiency and decrease in cone area due to oversized surround? I don't think there is any advanced technology with that woofer, it is simply oversized current technology with corresponding increase in weight and manufacturing costs. BTW-- have you figured out what the high pass freq is for a 8 ohm inductor having a 6" parallel wound iron core is? I would tell you, but that would ruin the fun.
I see whats going on here with your second question. BL refers to the physical strength of the motor structure--nothing more. Fact is, if one were to design a woofer with high enough BL and cone strength (assumed with high BL, or you would have a really stupid woofer), you would not have to worry one bit about rear chamber volume or throat dimension because the woofers strength would simply overpower any mechanical loading either of those two parameters could present. You could even pressurize the rear chamber and the woofer would still negate its effect.
I do not know the T/S parameters for the 2269, or I would offer a comparison.
T
Post by: Iain_Macdonald on December 28, 2007, 11:00:10 PM
Have a look at this link, and I think you might find that there is more to the driver than first seems apparent. Speak to the designer and see what he says about it being a "recycled car driver". have you looked at the videos yet?
http://www.acoupower.com/suspension.php
WRT the horn. Remember the pV constant. Also consider that just forcing air through the throat will ultimately, at stupid levels, just give you heat, and non linear airflow problems. ie massive distortion.
Have a nice weekend.
Iain.
Post by: Jeff Babcock on December 28, 2007, 11:14:51 PM
Best regards
Jeff
Post by: SteveKirby on December 29, 2007, 12:44:38 AM
After reconing 3 EVM subs, my opinion is that it's not worth it. I could have easily paid for B&C or 18Sound drivers for what I spent on the "great deal on old school stuff with a great rep" and the repairs.
Post by: Bob Leonard on December 29, 2007, 01:55:47 AM
| Elliot Thompson wrote on Fri, 28 December 2007 10:12 |
The JBL 2242 was a great improvement over the 2241. It works very well in a small cabinet, whereas the 2241 needed a sizeable box to prevent standing waves (Which comes from a speaker housed in a box too small for its requirements) in order to offer a better low frequency response. It also offers a higher xmax (9mm) over the 2241 (7.43 mm) to increase power handling. The power compression of the 2242 (- 3.3 dB @ 800 watts) falls in the same class as many other woofers in it's league. The VGC (Vented Gap Cooling) has been around ever since the days Eletrovoice was producing the EVM Series from the 70's. All in all the 2242 is good for a very small compact box. However, when we are talking large sub chambers the 2242 will fall short of expectation. Best Regards, |
Elliot,
Spot on and an important example. The 2241 is still a driver to be dealt with when used in large box 3 way Cinema systems. That's pretty much what it was designed for and that is where it truly excels even though it can be, and is often used in smaller boxes. It's also one of those drivers that audiophiles still crave and will pay top dollar for.
The 2242H drivers I use are designed for boxes in size 5-12 cubic feet (The same enclosure size as is recommended for the 2241H), a major consideration taken during my search as the boxes I planned to put these in, and eventually did put them in are 6.5 cubic feet. The 2242H is also considered a replacement for the 2241, however, you are correct in that many people feel the 2241 has a more "musical" sound for cinema use. I read that to imply "softer" sound, not as hard hitting. The 2242H hits pretty hard IMO if powered properly.
I also remember the EVM series but never equated that JBLs VGC had a similar design. Good catch, and very interesting, you must be an old fart like me.
http://www.jblpro.com/pages/pub/components/2241.pdf
http://www.jblpro.com/pages/pub/components/2242.pdf
Are they both alive and well? Yes they are.
http://www.jblpro.com/pages/cinema/subwoofers.htm
Note that the dual 18" box for cinema use is an 18 cubic foot box and uses 2241H drivers, not the 2242H. The 2241 and 2242 are both offered in the smaller single 8 cubic foot box, but I suspect that is only so that JBL can offer a higher powered version of the same product.
Now I'm having some fun. Thanks Elliot.
| Quote: |
Phil said... I don't recall JRX being discussed. There was one of those "JBL- Pro or not" arguments involving Mr. Duffin and IIRC Bob Leonard |
Even as dyed in the wool JBL as I am if there was any discussion about the JRX line between myself and Mr. Duffin it could only have been that I called the JRX series crap. Although in those discussions you could be right about anything for all I know.
And Mr. Duffin.
The 2269 is designed for exclusive use in the Vertec line. It is only available as a replacement for those boxes, at list price, through JBL parts. It is not available to the public and that is the reason they can not be purchased from JBL distributors as an after market product. This is JBLs policy with most of their products, and especially pro touring products using current technology. They will not release a product for after market purchase until that product has been superseded by the next generation of that product. In my case the 2242H has been replaced by the 2268H, a Neo driver. Good for me, I didn't want Neo.
My examples above concerning the 2241H and the 2242H should be enough to point out to anyone that EVERY driver regardless of manufacturer has an intended use. To simply state that an 18" driver is better because of it's mechanical or paper specs is pure nonsense. It is best to query the manufacturer, directly if possible as I did, than to blindly state that a driver, regardless of size, is best for an application because the specs on paper say so. I can also guarantee that a replacement for the 2269 is coming, and that there are other manufacturers out there with similar and maybe better products either available or in development. It would be ridiculous for anyone to think otherwise.
And here's a point for you. Full specs for the 2269 are NOT published. So based on your argument the only meaningful spec. I see that out shines the 2242 is power handling and Xmax (2" vs. 3.5"). The 2269 sensitivity rating is 92db, yet the 2242H driver has a rating of 99db. And further, the 2242 and 2269 are both capable of peak output to 136db. And finally, the 2242 will handle 1200 watts for 2 hours and 800 watts for ever, where as the 2269 will handle 1200 watts for 100 hours. Based on what's available I might save myself 2 grand and buy the 2242 for $650. However, the 2269 is designed for the Vertec specifically and an additional 2K would be fine by me if I was buying Vertecs. Am I saying the 2242 is a better driver? No I am not, far from it, but based on your arguments it may appear to be. Especially because as I said before, the full specs for the 2269 DRIVER are not published. So all of your arguments concerning what the best driver is go out the window.
And if you happen to run into Jacob Gop you can pass this on to him as well.
Have a great day,
http://www.jblpro.com/vertec1/pdf/JBL_VT4881A.v4.pdf
J. Bob Leonard
Post by: Elliot Thompson on December 29, 2007, 07:45:35 AM
| Bob Leonard wrote on Sat, 29 December 2007 06:55 |
I also remember the EVM series but never equated that JBLs VGC had a similar design. Good catch, and very interesting, you must be an old fart like me. ]J. Bob Leonard |
An "Old Fart" at 27 years of age. Now that's a first!
I wasn’t born with a golden spoon in my mouth so, I learned from the School Of Hard Knox. Which pretty much means do the best you can with what you can get your hands on. And, I’ve learned a lot using vintage gear.
I remember I used to power EVM 15Bs (200 watts) on QSC amps feeding them 600 watts (1200 @ 4 ohms for two EVM 15Bs from 90 Hertz – 1 KHz per amplifier) and never lost a driver despite when many others said the EVMs would be destroyed receiving that kind of power on a long-term basis. Of course, I’m talking around 10 years ago when I couldn’t afford tops.
Nowadays, gear is more affordable so, you rarely find many looking into the specifics of cabinet – driver integration anymore. They pretty much believe the specs and buy a ready made box and that’s that. Unfortunately, many still haven’t grasp what the specs really mean and, tend to assume the unthinkable. Not to mention tote things that only tells you half the story.
Sub driver replacement is always tricky because the least important specs get thrown around the most while the most vital specs are never mentioned. Even with the best tools at the users disposal, they need to have a general idea what they are aiming for. Not to mention have a good understanding how everything coincides together. Very few can predict the results before actually hearing the end result.
Best Regards,
Post by: Bob Leonard on December 29, 2007, 08:43:03 AM
I went to the same school and remember it well. As a matter of fact my father gave me two spoons. Then he said if I wanted silly things like guitars and speakers I should learn how to play them. Sure wish I was 27 again. It sucks to get old.
Post by: Dave Rickard on December 29, 2007, 10:41:32 AM
| Bob Leonard wrote on Fri, 28 December 2007 23:55 |
J. Bob Leonard |
Very good!
Post by: John Schmidt on December 29, 2007, 11:15:40 AM
| Bob Leonard wrote on Fri, 28 December 2007 22:55 |
Full specs for the 2269 are NOT published. So based on your argument the only meaningful spec. I see that out shines the 2242 is power handling and Xmax (2" vs. 3.5"). |
Actually, JBL has pretty comprehensive specs published: http://www.jblproservice.com/pdf/Thiele%20Small%20Parameters /Theile%20Parameters.pdf (see below for excerpt - Xmax is in mm - 25.4mm = 1"). Also, note that maximum excursion without damage is not necessarily equal to Xmax. I find it interesting that both the 2256 and 2268 actually have a greater published Xmax than the 2269. Of course, unpublished distortion numbers and other factors may have a greater influence on true sound quality...
John
Post by: Ivan Beaver on December 29, 2007, 12:04:52 PM
| Tim Duffin wrote on Fri, 28 December 2007 20:55 |
It is a demonstrated fact that the same horn design using a driver with higher BL than another driver performs at least as well if not better. The servodrive BT7 should be enough evidence of this fact for you-- the driver system in that device was created for max linear excursion with max force factor. If you invented another pistonic system with greater excursion but the same (or greater) force factor, your driver would perform better in that box, no question. T |
I am sure that all the horn designers are very appreciative of the insight you have given.
That will make horn design sooooo much easier now that they don't have to worry about all the other parameters that they have been struggling with geting the proper match between horn/back chamber/driver etc, all these years.
Just put a driver with the highest BL in any 'ol horn and you are done. EASY!
I/they never knew it was that easy
Thanks
Post by: Bob Leonard on December 29, 2007, 01:37:46 PM
Post by: Tim McCulloch on December 29, 2007, 02:07:25 PM
How about replying to the right post? You damn FlatView kids.....
Have fun, good luck... oh, and the rest of us "Tims" have voted Duffin out of our group. He needs a new name. Just kidding!... sort of.
Tim Mc
Post by: Tom Danley on December 29, 2007, 06:30:19 PM
“The point was that anyone can design around an inferior driver with exotic designs like tapped horns to make it approach a good one. But if the 2269 was used in a horn loaded configuration, I betcha it would be better than the same design using an inferior driver--huh!”
“It is a demonstrated fact that the same horn design using a driver with higher BL than another driver performs at least as well if not better. The servodrive BT7 should be enough evidence of this fact for you-- the driver system in that device was created for max linear excursion with max force factor. If you invented another pistonic system with greater excursion but the same (or greater) force factor, your driver would perform better in that box, no question.”
I am somewhat familiar with the BT-7 and such and figure it would be appropriate to add some additional details.
Everyone probably thinks of a horn as an acoustic impedance transformer, it gives the driver more of a coupling to the radiation part of the sound.
In that respect it is like a gear ratio too as one deals with both the ratio of motion and force.
In the horn, the compression ratio or ratio of the throat and driver areas is one additional “ratio” one has available, following the law of hydraulic behavior.
At the driver level, one has the motor strength ratio which defines how much Voltage is produced with a given radiator velocity and how much force is produced with a given current.
The latter is more common and called BL which in one definition is Newtons of force per Amp of current. For the driver, motor strength is not BL but rather either BL^2 / Rdc or BL / sqr root of Rdc (the latter force factor is in Newtons of force per Watt of dissipation)
So, motor strength includes the drivers resistance, it is not just BL.
In the horn, the “motor strength” is also reflected through the radiator so that if one put the same coil and magnet on a 18, 15, 12 and 10 inch drivers, one finds the effective motor strength increases progressively as the cone area goes down.
The other part of the driver issue is its mass which along with the electrical part, needs to be in the right range given the desired response and throat area.
To be clear though for both mass and motor strength, one finds that being at the peak of the relationship curve is desirable, neither too weak nor too strong, just right for that particular case horn is right.
One finds then that one can make a bass horn with a low cutoff at say 35Hz, using anything from a light wt 8 inch driver or 15 inch driver to say the Servodrive with is very strong and massive and get roughly the same efficiency with the right horns.
My approach with the Servodrives was to scale up a large radiator area with an appropriately strong motor (which requires a higher compression ratio) so that mech Xmax was about +6 dB over peak excursion at rated power.
With the Lab sub, I used a similar sized horn but being limited to conventional VC drivers, derived “weaker, smaller” drivers with the right parameters for that horn.
In these cases, heavy strong drivers have an advantage; they need a much smaller rear volume making the package smaller.
A curious thing about horns, as the frequency falls, one see’s the horn is not just a resistive load but has the effect of having more and more mass (inverse capacitance) if one has the optimum rear volume (actually a combination of suspension and air volume) these reactance’s cancel out which extends the low cutoff downwards in what is called “reactance annulling”
So why a Tapped horn?
I would bet it’s essentially safe to say that all bass horns are larger and heavier than their owners would prefer. In fact, at the size they are, they already represent a pretty significant departure from the normal horn math, which assumes a full dimension.
We also make horns a quarter wavelength long as that is the lowest mode they support even though a horn doesn’t reach its efficient range or theory until its 1 / 2 wl or more in length.
Here, a conventional bass horn’s response tends to have a prominent slope and peaks and dips, the horn is simply way too small to load with a constant resistance.
The Tapped horn having both sides of the driver coupled in, has a changing degree of coupling (phase shift), going from cancellation at DC, slight coupling at low cutoff (here a peak is) to full addition of both sides (where a dip usually is) so that in a given size, one has flatter response with less peak / dip stuff.
In other words, a horn that is too small has pronounced resonances, which causes the acoustic impedance to change accordingly, while proper proportions of the Tapped horn and driver provides a condition, which is like an acoustically accommodating or the inverse effect (when everything is perfect) leaving a nice curve that you couldn’t get from a normal horn in the same size package.
Now, the parameters needed for a Tapped horn are not like a regular small horn and the flattest response is similarly not from the most massive and strong driver.
In this case the driver has no back volume and so having the driver Fs somewhat above the low corner does the reactance annulling and motor strength governed by the horn parameters and radiator and maximum excursion.
Also, while one side has most of the acoustic load at the low cutoff, the range where the big valley usually is in a normal horn is where both sides are loaded in the Tapped horn.
So far as cheap drivers, sure one can make one work or with an expensive driver too.
In a Tapped horn, that 2269 would be best with a cutoff around 20Hz I think, driver sensitivity is typically raised 6 to 9 dB over the driver as a direct radiator.
I’ll try to model one later for fun.
Best,
Tom Danley
Post by: Tim Duffin on December 29, 2007, 08:07:24 PM
| Iain Macdonald wrote on Fri, 28 December 2007 20:00 |
Hi again, Have a look at this link, and I think you might find that there is more to the driver than first seems apparent. Speak to the designer and see what he says about it being a "recycled car driver". have you looked at the videos yet? http://www.acoupower.com/suspension.php WRT the horn. Remember the pV constant. Also consider that just forcing air through the throat will ultimately, at stupid levels, just give you heat, and non linear airflow problems. ie massive distortion. Have a nice weekend. Iain. |
The assymetrical deformation of sine waves and the pressure gradients of non smooth surfaces require simulation with FEA equipment--not simply saying "at stupid levels" What is the level-- EXACTLY, and provide the equation you used to determine it. If you can't find one, I can probably provide one for you.
T
Post by: Tom Young on December 30, 2007, 08:59:39 AM
One of us learned a few lessons from this.
Post by: Bob Leonard on December 30, 2007, 02:36:41 PM
| Tom Young wrote on Sun, 30 December 2007 08:59 |
Same thing with Klipsch bass horns, which used a purpose-designed Eminence cone driver. Back in my formative years a client asked me to sell him and install JBL's (much greater power handling, lower response, etc) and they did not work nearly as well and quickly failed due to the loading of that bass horn (I think these were LaScala's). One of us learned a few lessons from this. |
And there you go Tom, just one more example of a good driver for the wrong job. It won't matter whose driver is used and what the specs are. If it's the wrong driver for the job you'll find out soon enough.
Post by: Ivan Beaver on December 30, 2007, 02:42:13 PM
Post by: Bob Leonard on December 30, 2007, 03:03:33 PM
| Ivan Beaver wrote on Sun, 30 December 2007 14:42 |
With horns it is not so much what is the "best" driver, but rather what is right for the job at hand. |
Ivan,
We're all saying the same thing and it's amazing some people still don't quite get it.
Post by: Bennett Prescott on December 30, 2007, 03:35:38 PM
Post by: Iain_Macdonald on December 30, 2007, 03:48:37 PM
| Tim Duffin wrote on Sun, 30 December 2007 01:07 | ||
The assymetrical deformation of sine waves and the pressure gradients of non smooth surfaces require simulation with FEA equipment--not simply saying "at stupid levels" What is the level-- EXACTLY, and provide the equation you used to determine it. If you can't find one, I can probably provide one for you. T |
| Tim Duffin |
The assymetrical deformation of sine waves and the pressure gradients of non smooth surfaces require simulation with FEA equipment |
FEA(Finite Element Analysis) is an analytical method, not a piece of "equipment". Others would use BEM or CFD. With the proviso that it isn't a steady state flow problem. Smoothness of surface is relatively unimportant when we are talking about a large cross section sub horn. If you've been reading the JBL paper which talks about flared ports then you are looking at a different issue.
| Tim Duffin |
What is the level-- EXACTLY, and provide the equation you used to determine it. If you can't find one, I can probably provide one for you. |
Let's see what you come up with, and please explain what is happening, and how you apply it to the problem. Together with a worked example.
Iain.
Post by: Tim Duffin on December 30, 2007, 04:16:06 PM
Oh, and about the "large" cross sectional horn area--- how large? You seem to avoid saying anything concrete. So, you first: I would like to see how you came up with the hypothesis that "stupid" levels cause non linear flow simply due to heat. If you just made that up, I understand, not many people on the LAB ever back up anything they type with actual math.
T
Post by: Tom Danley on December 30, 2007, 04:56:59 PM
The asymmetric distortion of sine waves that Tim mentions is in fact a reality but it is not an air velocity effect but rather a pressure effect that effects radiated sound as well as sound in a box enclosure.
The speed of sound changes with temperature, as air becomes ‘thinner” as it is heated its velocity increases. This change in temperature when pressure is changed also effects the air in a sealed boxes, making it non-linear (google Siegfried Linkwitz’s web site if curious).
Meanwhile, In an intense sound wave, the pressure side of the wave is slightly warmer and travels a little faster than the rarified or cooler side of the wave. A pure sine wave at very high spl’s bunches up into a something like a saw tooth wave.
In a horn one finds that the degree this is a problem is related to both pressure and how high the horn goes compared to how low it goes. The issue here is that at the hf cutoff, the wider bw horn has the high pressure contained by a slower expansion giving it more wavelengths to effect it.
In bass horns, one rarely if ever has sound pressures that high (that this is a problem) while driver linearity is always an issue.
Curiously, while logic would suggest that aerodynamic considerations would be a valid avenue for improvement, it turns out the actual velocities inside the horn are not all that great.
I had a fellow build a completely sculptured and glassed version of a Servodrive cabinet once to test. The guy spent a lot of time on it and it looked beautiful (weighed an extra 80 pounds or something too) and I was excited to see the difference.
So, the reality check was taking a stock horn and after carefully measuring the custom box, popped the same drive module in the stock cabinet and re-measured.
It was somewhat dumbfounding and we repeated the test twice, the slick radiused aerodynamic enclosure had a slightly higher cutoff AND slightly less output.
The issue was the velocity is not high enough to benefit much from all that attention to detail BUT in making it so cool, the horn got slightly smaller in its internal volume.
Whodathunkit?
Best,
Tom Danley
Post by: John Roberts {JR} on December 30, 2007, 05:33:44 PM
| Tim Duffin wrote on Sun, 30 December 2007 15:16 |
Well now you are just getting all semantic. Finite Element Analysis must take place within a computer system-- we agree on that?! So anyone who uses the method of FEA must have a computer at hand-- it seems like you are arguing about nothing. Oh, and about the "large" cross sectional horn area--- how large? You seem to avoid saying anything concrete. So, you first: I would like to see how you came up with the hypothesis that "stupid" levels cause non linear flow simply due to heat. If you just made that up, I understand, not many people on the LAB ever back up anything they type with actual math. T |
I'm not sure if it's sloppy language or sloppy thinking but FEA is a technique kind of like addition or subtraction. Just because most addition and subtraction is done with calculators instead of pencil and paper does mean they require a calculator.
FEA "software" would naturally be used in connection with a computer, but finite element analysis is just an iterative analysis process where you accumulate results over a larger number of simple calculations instead of using a few advanced calculations involving calculus or some higher level math technique.
Ironically "showing all work" with FEA could involve a lot of paper.
It is true that it takes modern (digital) computers to make this step intensive crude iterative process actually practical. Now what does this have to do with the price of tea in China? More noise.
JR
Post by: Iain_Macdonald on December 30, 2007, 05:53:30 PM
| Tim Duffin wrote on Sun, 30 December 2007 21:16 |
Well now you are just getting all semantic. Finite Element Analysis must take place within a computer system-- we agree on that?! So anyone who uses the method of FEA must have a computer at hand-- it seems like you are arguing about nothing. Oh, and about the "large" cross sectional horn area--- how large? You seem to avoid saying anything concrete. So, you first: I would like to see how you came up with the hypothesis that "stupid" levels cause non linear flow simply due to heat. If you just made that up, I understand, not many people on the LAB ever back up anything they type with actual math. T |
Semantics? You obviously used terminology that you didn't understand.
Stupid= Not practically realisable in a conventional/normal design.
Where do I say that it is simply due to heat?
I said "WRT the horn. Remember the pV constant. Also consider that just forcing air through the throat will ultimately, at stupid levels, just give you heat, and non linear airflow problems. ie massive distortion." Have you ever put your finger at the output of a bicycle pump and then compressed the plunger. Did you get a burn from the escaping high pressure air. An old playground trick.
You wanted maths, so here's a little.
1) Boyles law. V
Post by: Tim Duffin on December 31, 2007, 12:30:32 AM
| Iain Macdonald wrote on Sun, 30 December 2007 14:53 | ||||||||||
Semantics? You obviously used terminology that you didn't understand. Stupid= Not practically realisable in a conventional/normal design. Where do I say that it is simply due to heat? I said "WRT the horn. Remember the pV constant. Also consider that just forcing air through the throat will ultimately, at stupid levels, just give you heat, and non linear airflow problems. ie massive distortion." Have you ever put your finger at the output of a bicycle pump and then compressed the plunger. Did you get a burn from the escaping high pressure air. An old playground trick. You wanted maths, so here's a little. 1) Boyles law. V Post by: Iain_Macdonald on December 31, 2007, 05:56:25 PM
|