Post by: Adam Schaible on November 17, 2009, 06:43:48 PM
Found some plans on the interweb for a 6th order bandpass cabinet.
Finishing up the build, so I figured I'd post some build pics. I plan to finish it in Rhino liner. It uses B&C 18PZB 100 drivers.
Plan Diagram
I'll post some finished pics here and maybe some measurements!
Post by: Aaron Kovacik on November 18, 2009, 12:28:39 AM
Post by: Marjan Milosevic on November 18, 2009, 11:53:49 AM
Nice build BTW.
Post by: Adam Schaible on November 18, 2009, 11:57:25 AM
Post by: Elliot Thompson on November 18, 2009, 03:14:27 PM
| Adam Schaible wrote on Wed, 18 November 2009 16:57 |
Yeah, thanks! Obviously it's not the same, and I'm not trying to be identical - but I think I can get pretty close for much less coin. |
So what is the frequency response of the box?
You seemed to neglect to post the most important part.
Best Regards,
Post by: Douglas R. Allen on November 18, 2009, 05:06:23 PM
How wide is it? Looks big. I'll have to convert cm to inches.
Douglas R. Allen
Post by: Adam Schaible on November 18, 2009, 05:09:06 PM
It's 45.6" x 22.8" x 36.2" - so yeah, kinda on the big side.
Post by: Adam Schaible on November 18, 2009, 07:03:20 PM
| Elliot Thompson wrote on Wed, 18 November 2009 14:14 | ||
So what is the frequency response of the box? You seemed to neglect to post the most important part. Best Regards, |
I haven't measured it yet
Will probably have drivers in it tomorrow.
Post by: Adam Schaible on November 18, 2009, 10:42:15 PM
Post by: Marjan Milosevic on November 19, 2009, 11:24:11 AM
Post by: Adam Schaible on November 20, 2009, 08:33:04 PM
The one difference - it sounds a LOT better than the SRX 728. Much tighter - when I played metal songs with lots of double bass, the 728 was much less tight. I'll try to get some measurements in an open space over concrete.
SRX 728 below - for size comparison.
Post by: Douglas R. Allen on November 21, 2009, 06:37:28 AM
| Adam Schaible wrote on Fri, 20 November 2009 20:33 |
So I hooked it up today... its similar SPL to the JBL SRX 728 (only other sub I tested against). I had it stacked on a 728 - so very hard to say - also in a small room. The one difference - it sounds a LOT better than the SRX 728. Much tighter - when I played metal songs with lots of double bass, the 728 was much less tight. I'll try to get some measurements in an open space over concrete. SRX 728 below - for size comparison. |
Nice looking build!
As I'm sure you may know its not a good idea to test subs placed next to each other. Or have them at different heights or different locations.
Each box is tuned to a certain freq. and will produce that note when excited by another sub. Like blowing across a pop bottle. Measure one sub at a spot. Move it well away and test the next.
I have a spare set of 18's looking for a home. How big is the back door and is it 22.8 inches overall wide for the speaker or is that the inside measurement?
Thanks and keep the test results coming!
Douglas R. Allen
Post by: Adam Schaible on November 21, 2009, 10:13:36 AM
As far as hight, the interior is 21 7/16 tall - but you could build the access panel to fit just about any 18" driver. Right now, I have to tilt the driver to get it through - but I made mine a bit smaller than "them".
According to the plans, their access panel actually extends over the baffle plates by about 1/8" - 1/4". I did this at first, but had to scrap that build and start over. I think they have a CNC that layers their access panel so that although the back dimension is wider than the "allowed" amount, the inner dimension is probably 3-5cm smaller.
Either way, you could load any driver - but I made this door just big enough for the 18PZB100 - not sure how a different driver would work though.
Post by: Douglas R. Allen on November 22, 2009, 10:20:19 AM
The box could be handled by one person this way. I am guessing both drivers still only "see" half of the center volume?
Should you have a chance find out the weight of this box. Looks like a fun winter project.
Thanks!
Douglas R. Allen
Post by: Adam Schaible on November 22, 2009, 10:34:48 AM
It's not so heavy - it's a bit heavier than the 728, but you can only tell if you pick up one, then the other. Pickup a few things in between and I wouldn't notice.
That said, there are casters on the rear by the access panel. Since the handles let you carry the sub with that direction facing down, you really only need to lift it for steps/etc.
I spent an hour or so listening to the sub with various music types. I set the HP to 30hz L/R 24db/octave and the LP to 85hz 24 L/R. It sounds very very musical. I'll have to try and measure it. It just sounds really really nice.
Post by: Josh Billings on November 23, 2009, 11:13:23 AM
| Marjan Milosevic(MarjanM) wrote on Wed, 18 November 2009 08:53 |
I am sure that he IS aware. Just not mentioning any names and models Nice build BTW. |
Somebody fill me in
Post by: Adam Schaible on November 23, 2009, 11:46:54 AM
| Josh Billings wrote on Mon, 23 November 2009 10:13 | ||
Somebody fill me in |
PM'd
Post by: Duncan McLennan on November 23, 2009, 10:02:42 PM
Post by: Adam Schaible on November 23, 2009, 10:29:42 PM
| Duncan McLennan wrote on Mon, 23 November 2009 21:02 |
Adam, is there a (permanent) narrow diagonal brace inside the chambers? Or was that just in there for construction's sake. |
Hi Duncan,
I removed them after the cabinet was sealed up. Initially they were used (in conjunction with other techniques) to make sure the back panel was at a perfect 90 degree angle to the base. After a few panels were set it probably served no purpose, but I figured I would let the top cure before removal just in the rare case something wanted to shift.
Post by: Nick Enright on November 24, 2009, 03:51:25 PM
Post by: Martin Queckenstedt on November 24, 2009, 04:12:43 PM
Post by: Tom Manchester on November 27, 2009, 06:26:31 PM
FWIW The company in question doesn't just make good boxes, it's the system working together that makes the difference. Some of us payed the price to play with the real deal system, and you will not get that with just the sub box. Have fun with it.
Post by: Adam Schaible on November 27, 2009, 07:26:54 PM
| Tom Manchester wrote on Fri, 27 November 2009 17:26 |
I wonder what the company that has this as a current production model would have to say about cloning their products? FWIW The company in question doesn't just make good boxes, it's the system working together that makes the difference. Some of us payed the price to play with the real deal system, and you will not get that with just the sub box. Have fun with it. |
Whatever they might say, I doubt I'd understand it!!!
On a more serious note, there is absolutely nothing illegal/wrong with cloning another product. It gets illegal if you try to sell and market the product. Make a minor change or two and it's legal again - but this site isn't for lawyers anyway.
There's not that much DSP trickery in a sub box - contrary to what marketing departments might have you believe. It might take some tweaking to integrate with the tops of my choice, but outside of that - good bass is good bass. No phase plug witchery or anything like that to worry about. I'm not sure where I implied that a single sub clone would give me their full system.
Post by: Tom Manchester on November 27, 2009, 07:33:09 PM
| Adam Schaible wrote on Fri, 27 November 2009 19:26 |
There's not that much DSP trickery in a sub box - contrary to what marketing departments might have you believe. |
In most instances yes, but not in this case.
Post by: Bennett Prescott on November 27, 2009, 11:41:53 PM
| Adam Schaible wrote on Fri, 27 November 2009 19:26 |
There's not that much DSP trickery in a sub box - contrary to what marketing departments might have you believe. It might take some tweaking to integrate with the tops of my choice, but outside of that - good bass is good bass. No phase plug witchery or anything like that to worry about. |
This is a bandpass subwoofer. You will need substantial EQ, contrary to what you may believe. Regardless of what I think about copying a major manufacturer's work, at least understand what you've built.
Post by: Adam Schaible on November 28, 2009, 12:01:20 AM
| Bennett Prescott wrote on Fri, 27 November 2009 22:41 | ||
This is a bandpass subwoofer. You will need substantial EQ, contrary to what you may believe. Regardless of what I think about copying a major manufacturer's work, at least understand what you've built. |
EQ doesn't mean DSP trickery. Pretty sure we can all tweak EQ for what we want, and I'm working on phase traces for the originals.
Post by: Bennett Prescott on November 28, 2009, 11:18:18 AM
Post by: Adam Schaible on November 28, 2009, 05:06:49 PM
Post by: The Guy on November 28, 2009, 06:45:38 PM
-J
Post by: Ivan Beaver on November 28, 2009, 07:25:01 PM
| Jim Bowersox wrote on Sat, 28 November 2009 18:45 |
How do you find that they work in large numbers? Your website lists that you have 8 "d&b B2 clones" with a link to the d&b website. -J |
I would think there is some sort of infringement in that regard. It is one thing to call a copy your own model number, but when mentioning the particular model they are copied after and linking to THEIR website, surely something is "illegal" in some regards.
Post by: Douglas R. Allen on November 28, 2009, 07:36:10 PM
This is a bandpass sub-woofer. You will need substantial EQ, contrary to what you may believe. Regardless of what I think about copying a major manufacturer's work, at least understand what you've built.[/quote]
Not always. Of all things the yellow trace is a peavey subcompact 18.
More or less +/- 3db in its bandpass 45 to 150 hz. This is with no eqing and it looked like this in most of places I used them. The green trace is a QSC HPR sub.
Now of course it doesn't come even close to the output or freq response the the b2 but it does have a pretty flat response none the less. Not too bad for a bandpass low freq box.
Post by: John Roberts {JR} on November 28, 2009, 08:49:30 PM
The protected non-commercial use of patented technology is to promote science and technology research and development, not to allow small competitors to use IP for commercial gain without paying for it..
Look for coal in your stocking.
JR
Post by: Caleb Dick on November 28, 2009, 11:51:20 PM
As others have mentioned, having the same drivers (if they really are exactly the same and the real manufacturer didn't tweak them a bit) and the same looking box does not automatically mean the same performance and consistency.
Caleb
Post by: Adam Schaible on November 29, 2009, 01:11:32 AM
| Adam Schaible wrote on Wed, 18 November 2009 10:57 |
Yeah, thanks! Obviously it's not the same, and I'm not trying to be identical - but I think I can get pretty close for much less coin. |
Should read the thread.
I think there's two (or more) types of people out there. Some people who have invested 250k+ in a rig get bent out of shape when someone with less coin and more time try to get close. I understand people being upset - but the cabs I am building/have built will more than likely have zero impact on you. I'd imagine these people get 25-50 times more than I do for a show, and I understand that too. Everyone has their place. My client want it to sound good and not break the bank - our music scene is on life support and there simply isn't money in it. We have been hit hard by the clear channel dictatorship and while there are a few local providers that can afford top notch gear - they are not willing to work with less than a 5 figure budget - understandably so.
There are others (99% of the people I work for) that can barely afford a 4 figure budget. I strive to offer the best quality in that price range. Building my own cabs, be it clones/etc allows me to do that.
I just got home from mixing a show - FoH was 8 turbo floodlights over 16 TSW-721's per side. All powered by crest amps and a PM3500 desk -- drawmer comps/gates, blah blah.
Anyway, I can get pretty darn close to that with my 30k rig, and I'm pretty sure they have over 300k in theirs.
Post by: The Guy on November 29, 2009, 11:08:57 AM
| Adam Schaible wrote on Sun, 29 November 2009 01:11 |
I just got home from mixing a show - FoH was 8 turbo floodlights over 16 TSW-721's per side. All powered by crest amps and a PM3500 desk -- drawmer comps/gates, blah blah. Anyway, I can get pretty darn close to that with my 30k rig, and I'm pretty sure they have over 300k in theirs. |
Again, looking at your website, you really need a reality check if you think a Presonus StudioLive mixer, no monitor console, 4 wedges, B2 copies, and 10 of some 1x12 homebrew mains cabinet will EVER be viable in even the smallest national (even regional) act situation. I can say that I don't know of a single engineer that would ever consider your console acceptable, let alone homemade main speakers and monitors from FOH. Even if your fake B2's perform as real ones do (which they will not if you don't have d&b amps and the correct drivers), the rest of the rig is not even in the ballpark.
And, although the Floodlight/21/PM3500 rig you speak of is a bit long in the tooth, I can assure you that comparing your rig to that one is like bringing a rubber chicken to a gunfight. Stick to being a wedding DJ and leave the concert sound to the big boys.
-J
Post by: Phil Lewandowski on November 29, 2009, 11:26:47 AM
| Jim Bowersox wrote on Sun, 29 November 2009 11:08 | ||
Again, looking at your website, you really need a reality check if you think a Presonus StudioLive mixer, no monitor console, 4 wedges, B2 copies, and 10 of some 1x12 homebrew mains cabinet will EVER be viable in even the smallest national (even regional) act situation. I can say that I don't know of a single engineer that would ever consider your console acceptable, let alone homemade main speakers and monitors from FOH. Even if your fake B2's perform as real ones do (which they will not if you don't have d&b amps and the correct drivers), the rest of the rig is not even in the ballpark. And, although the Floodlight/21/PM3500 rig you speak of is a bit long in the tooth, I can assure you that comparing your rig to that one is like bringing a rubber chicken to a gunfight. Stick to being a wedding DJ and leave the concert sound to the big boys. -J |
Hey Jim,
I don't know if Adam is really trying to compete with the big boys from when I've talked to him. And I am pretty sure he is aware of that because I think he mentioned that in a previous post.
It sounds like something where if he can get these homemade subs to be even close to the performance of the real cabs that it is a good sub to bring out when he needs some real subbage. But I don't think he is planning to use them to bid on A-list nationals.
Take Care!
Phil
Post by: Adam Schaible on November 29, 2009, 12:00:45 PM
| Jim Bowersox wrote on Sun, 29 November 2009 10:08 | ||
Again, looking at your website, you really need a reality check if you think a Presonus StudioLive mixer, no monitor console, 4 wedges, B2 copies, and 10 of some 1x12 homebrew mains cabinet will EVER be viable in even the smallest national (even regional) act situation. I can say that I don't know of a single engineer that would ever consider your console acceptable, let alone homemade main speakers and monitors from FOH. Even if your fake B2's perform as real ones do (which they will not if you don't have d&b amps and the correct drivers), the rest of the rig is not even in the ballpark. And, although the Floodlight/21/PM3500 rig you speak of is a bit long in the tooth, I can assure you that comparing your rig to that one is like bringing a rubber chicken to a gunfight. Stick to being a wedding DJ and leave the concert sound to the big boys. -J |
Congrats on proving 1 thing - you are a total dbag.
Maybe you were too belligerent to actually read the thread, either way - as Phil as said -- you can have all the national acts and their 25k budget. I ASSure you, the rig I provide for the amount of money it costs is unparalleled.
My clients are usually festival operators, club owners, etc that need portable PA. They have $2500ish to spend on lights, sound, and staging.
Tell me what you provide for $1400 that's so much better?
I do agree the turbo rig is old .. but the fact remains it's THE premier club around here and has had all up-and-coming national acts prior to the Clear Channel take over. It's a good baseline, and my rig sounds better, and gets louder. Not sure what is so rubber about that.
Again, there are some of you - and I do respect this - that can actually support top level rig costs. I simply can't. What's wrong with me doing the best with my budget?
Furthermore, I realize my gear is toys-r-us compared to some you guys. For some reason that bothers you more than it bothers me (none at all). I understand it's limitations, and it seems like the majority of you bashing me here seem to think I'm trying to compete with national sound companies. I'm not trying to convince anyone that my rig can compete with any top-level rigs. I am a 1-2 person operation and I play in that space. Is that so hard to understand?
Tear me and my company apart all you want, but it's working for my clients. They are happy with the value (Quality / Cost) that I provide.
Post by: The Guy on November 29, 2009, 12:19:46 PM
| Adam Schaible wrote on Sun, 29 November 2009 12:00 |
Congrats on proving 1 thing - you are a total dbag. |
Before you dig your own grave any deeper, remember that I was not childishly insulting you, but rather calling out your statement of your rig being superior to a nationally-acceptable system.
| Adam Schaible wrote on Sun, 29 November 2009 12:00 |
Maybe you were too belligerent to actually read the thread, either way - as Phil as said -- you can have all the national acts and their 25k budget. I ASSure you, the rig I provide for the amount of money it costs is unparalleled. |
As I recall, this thread started with you bragging about your d&b B2 sub clones. Again, keep digging.
| Adam Schaible wrote on Sun, 29 November 2009 12:00 |
My clients are usually festival operators, club owners, etc that need portable PA. They have $2500ish to spend on lights, sound, and staging. Tell me what you provide for $1400 that's so much better? |
Without getting into a detailed pissing contest, I can tell you that $1400 gets you more than you'd expect for a small festival PA. Well, more than you're providing anyway.
| Adam Schaible wrote on Sun, 29 November 2009 12:00 |
I do agree the turbo rig is old .. but the fact remains it's THE premier club around here and has had all up-and-coming national acts prior to the Clear Channel take over. It's a good baseline, and my rig sounds better, and gets louder. Not sure what is so rubber about that. |
The Turbo rig you described was a world-class high performance system in its day, and still is a very viable system in many markets. Your system is not in the same category, and will not ever be competitive in the same market. Sound quality aside, there are certain conditions that your system will not satisfy, such as a need for more than 16 channels, a separate monitor mixer, more than 4 wedges, etc. I can say in no uncertain terms, that virtually every rider act (even tiny ones) that I've provided for would not find your rig acceptable for the above mentioned reasons.
| Adam Schaible wrote on Sun, 29 November 2009 12:00 |
Again, there are some of you - and I do respect this - that can actually support top level rig costs. I simply can't. What's wrong with me doing the best with my budget? Furthermore, I realize my gear is toys-r-us compared to some you guys. For some reason that bothers you more than it bothers me (none at all). |
Nobody said that you weren't doing the best you could. Dream big! In the meantime, I suggest that you get a can (or better yet, a case) of this:
Post by: Adam Schaible on November 29, 2009, 12:30:46 PM
Maybe your market is different than mine. For a 1000 person show (50x75 coverage area) around here you're looking at $2500 for FoH, a separate monitor rig is another $1000. This is typically 4 SB1000's and 2-4 KF650's. Probably a GL2400 and some DBX131's. Then they make you buy power from them, so another $300-$500 for generators/fuel.
That's my competition.
Post by: Ivan Beaver on November 29, 2009, 09:03:52 PM
If you got the plans from where I think you got them (they look identical), are you sure they are correct? I don't know-but just wondering.
In looking around at various other plans of other commericial subs, some of them are not even close to what is going on inside. Outside, they look the same-but it is "what is under the hood" that makes the difference in proper designed performance and something that is "guessed at".
Your copycat subs may (or may not) be the same as the real thing. Only side by side measured responses would tell.
Post by: Adam Schaible on November 29, 2009, 09:17:01 PM
Anyway, got around to measurement today. I've described my measurement in the past, it's anything but scientific - but good 'nuff for me (just for comparison sake). I use a crown I-Tech HD amplifier - cheapo multimeter hooked up to the speakon to get voltage measured. I went with 2v - impedance is over 4 ohms (avg about 4.5) so it's not quite 1 watt, but --- close enough for me. I haven't done an impedance sweep but I will and post it later. Used a rat shack spl meter at 1m (finally got my metric tape)
It's definitely not good down to 30hz - 18db down from 40hz.
Here are some quick numbers.
30|90
35|99
40|108
45|111
50|111
55|111
60|111
65|112
70|114
75|115
80|115
85|116
90|115
95|115
100|115
it's between 110 and 113 through 200hz. Looks to need about 5db cut closer to the crossover frequency but some people bump that for kick drum reinforcement anyway.
Post by: Ivan Beaver on November 29, 2009, 09:37:44 PM
| Adam Schaible wrote on Sun, 29 November 2009 21:17 |
I wouldn't bet tooo much on it or anything - but I'm reasonably sure. I actually hope they aren't because they sound great and I'm super happy with them - so if they aren't correct maybe I'd feel better about it. I've spoken to a few people that own/have owned/have rented them to get a feel for the accuracy of the plans. Some of the finer details may be off-target but overall. Anyway, got around to measurement today. I've described my measurement in the past, it's anything but scientific - but good 'nuff for me (just for comparison sake). I use a crown I-Tech HD amplifier - cheapo multimeter hooked up to the speakon to get voltage measured. I went with 2v - impedance is over 4 ohms (avg about 4.5) so it's not quite 1 watt, but --- close enough for me. I haven't done an impedance sweep but I will and post it later. Used a rat shack spl meter at 1m (finally got my metric tape) It's definitely not good down to 30hz - 18db down from 40hz. Here are some quick numbers. 30|90 35|99 40|108 45|111 50|111 55|111 60|111 65|112 70|114 75|115 80|115 85|116 90|115 95|115 100|115 it's between 110 and 113 through 200hz. Looks to need about 5db cut closer to the crossover frequency but some people bump that for kick drum reinforcement anyway. |
Me thinks you need a calibrated meter. Either that, or since you said it was pretty close to the 728, the JBL is a lot louder than on the spec sheets and others have measured.
Something is wrong.
Post by: Adam Schaible on November 29, 2009, 09:41:26 PM
Are you suggesting these numbers are too high?? I know my 728 measurements were higher than expected. I wasn't trying to say these figures are accurate, but I think they are accurate-ish in relation to each other, so it seems reasonably flat to me.
Post by: Silas Pradetto on November 30, 2009, 10:04:31 AM
| Adam Schaible wrote on Sun, 29 November 2009 21:41 |
I'm sure my meter sucks. I can look into my SRX 728 measurements. When I said it was similar, it was 100% subjective. Are you suggesting these numbers are too high?? I know my 728 measurements were higher than expected. I wasn't trying to say these figures are accurate, but I think they are accurate-ish in relation to each other, so it seems reasonably flat to me. |
Also remember that the C weighting isn't flat to 20Hz, so it will have some inherent rolloff in the lower frequencies.
Post by: Art Welter on November 30, 2009, 12:44:43 PM
| Adam Schaible wrote on Sun, 29 November 2009 19:17 |
I wouldn't bet tooo much on it or anything - but I'm reasonably sure. I actually hope they aren't because they sound great and I'm super happy with them - so if they aren't correct maybe I'd feel better about it. I've spoken to a few people that own/have owned/have rented them to get a feel for the accuracy of the plans. Some of the finer details may be off-target but overall. Anyway, got around to measurement today. I've described my measurement in the past, it's anything but scientific - but good 'nuff for me (just for comparison sake). I use a crown I-Tech HD amplifier - cheapo multimeter hooked up to the speakon to get voltage measured. I went with 2v - impedance is over 4 ohms (avg about 4.5) so it's not quite 1 watt, but --- close enough for me. I haven't done an impedance sweep but I will and post it later. Used a rat shack spl meter at 1m (finally got my metric tape) It's definitely not good down to 30hz - 18db down from 40hz. Here are some quick numbers. 30|90 35|99 40|108 45|111 50|111 55|111 60|111 65|112 70|114 75|115 80|115 85|116 90|115 95|115 100|115 it's between 110 and 113 through 200hz. Looks to need about 5db cut closer to the crossover frequency but some people bump that for kick drum reinforcement anyway. |
Those numbers look about 10 dB too hot, are you sure you were not off one switch setting?
Post by: Adam Schaible on November 30, 2009, 12:50:32 PM
I should say that my objective was to measure the response curve, not necessarily determine output level.
Post by: Art Welter on November 30, 2009, 01:03:59 PM
| Adam Schaible wrote on Mon, 30 November 2009 10:50 |
I will give it another shot sometime soon - I should say that my objective was to measure the response curve, not necessarily determine output level. |
To achieve those objectives you should measure at a greater distance than one meter and use a SPL meter that does not roll off the bottom end response.
Post by: Adam Schaible on November 30, 2009, 01:05:42 PM
Post by: Phil Lewandowski on November 30, 2009, 01:22:29 PM
| Adam Schaible wrote on Mon, 30 November 2009 13:05 |
Is there any SPL meter or process you might recommend? I have a radio shack meter, as well as a DBX reference mic, and SMAART. I'm not quite sure how to calibrate smaart, but I suppose that would be the cheapest way to do this? |
It seems like your simplest way to just get the response is to just use Smaart. My guess is the dbx mic will be decently accurate down below 100hz?
Since you aren't looking to figure out the sensitivity you don't have to really calibrate it for that.
Or I could be way off!
Take Care,
Phil
Post by: Art Welter on November 30, 2009, 01:37:26 PM
| Adam Schaible wrote on Mon, 30 November 2009 11:05 |
Is there any SPL meter or process you might recommend? I have a radio shack meter, as well as a DBX reference mic, and SMAART. I'm not quite sure how to calibrate smaart, but I suppose that would be the cheapest way to do this? |
Smaart would be fine, you can calibrate it's SPL to your dB meter so it agrees in the midrange. Using band limited pink noise makes the process more simple.
One thing impossible to detect with a simple dB meter is harmonic content.
A 40 HZ signal input that produces a lot of 80 and 120 HZ may read quite high on a dB meter, which is frequency blind.
The worse the harmonic distortion, the higher the indicated sensitivity when using sine waves and a dB meter.
Post by: David Morison on December 02, 2009, 07:45:58 AM
| Ivan Beaver wrote on Mon, 30 November 2009 02:37 |
Me thinks you need a calibrated meter. Either that, or since you said it was pretty close to the 728, the JBL is a lot louder than on the spec sheets and others have measured. Something is wrong. |
Hi Ivan,
Certainly won't argue with you that a calibrated set up of some kind would give more accurate results.
One thing that may be skewing the results though is if he did the measurements in the room pictured earlier in the thread. Although we can't see all of the room, it looks like the cabs could be in near enough 1/8th space, which would inflate the apparent loudness of the 728 beyond what we know from the spec sheet and the other measurements you mention. (That would obviously also inflate the SPL of the DIY cab to a similar degree.)
Could explain the difference perhaps?
Cheers,
David.
Post by: Phil Lewandowski on December 02, 2009, 01:14:23 PM
| David Morison wrote on Wed, 02 December 2009 07:45 | ||
Hi Ivan, Certainly won't argue with you that a calibrated set up of some kind would give more accurate results. One thing that may be skewing the results though is if he did the measurements in the room pictured earlier in the thread. Although we can't see all of the room, it looks like the cabs could be in near enough 1/8th space, which would inflate the apparent loudness of the 728 beyond what we know from the spec sheet and the other measurements you mention. (That would obviously also inflate the SPL of the DIY cab to a similar degree.) Could explain the difference perhaps? Cheers, David. |
IIRC, the measurement of the SRX728 was outside and from what I remember seemed to be pretty in the ball-park of what it should be. I would assume that Adam got the DIY cab outside as well.
Take Care,
Phil
Post by: Evan Kirkendall on December 02, 2009, 02:18:48 PM
(Sorry for the shit picture)
Evan
Post by: Adam Schaible on December 02, 2009, 02:28:39 PM
Post by: Jeff Babcock on December 02, 2009, 02:33:18 PM
Frequency response (-5 dB) STANDARD 37 Hz - 90 Hz / INFRA 32 Hz - 68 Hz
Post by: Evan Kirkendall on December 02, 2009, 02:38:15 PM
Evan
Post by: Adam Schaible on December 02, 2009, 02:43:11 PM
Post by: Evan Kirkendall on December 02, 2009, 02:47:05 PM
| Adam Schaible wrote on Wed, 02 December 2009 14:43 |
Thanks for the info. I think there's a lot of low end boost going on, but if truly used in infra mode it sounds pretty good. It seems like you lose some clarity when boosting the lows that much (at least on my cab) -- I'm not sure if the original is similar or not. |
There may some LF boosts going on, but mine are clean as a bell all the way up to limit.
Evan
Post by: Adam Schaible on December 02, 2009, 03:01:30 PM
It would be interesting to A/B -- anyone near cincinnati?
One more question - have you measured voltage from the D12? I've measured excursion into the 1250w range and it was minimal, less than 8-9mm (4mm or so in either directon). Now - a 30hz sine wave will bury it, but standard program material seems to have a ton of power handling.
Post by: Art Welter on December 02, 2009, 03:17:39 PM
| Adam Schaible wrote on Wed, 02 December 2009 13:01 |
Well when running in INFRA mode it looks like it rolls off at the kick drum. It would be interesting to A/B -- anyone near cincinnati? One more question - have you measured voltage from the D12? I've measured excursion into the 1250w range and it was minimal, less than 8-9mm (4mm or so in either directon). Now - a 30hz sine wave will bury it, but standard program material seems to have a ton of power handling. |
Adam,
Sounds like your FB is too high, have you determined what it is yet?
Post by: Adam Schaible on December 02, 2009, 03:23:06 PM
Post by: Art Welter on December 02, 2009, 03:26:12 PM
| Adam Schaible wrote on Wed, 02 December 2009 13:23 |
I have not - admittedly I am not sure how to do this accurately. |
Put a dot on the speaker, sweep LF sine wave tone, excursion minima is FB.
You will probably need a mirror on a stick to see your cone.
Post by: Adam Schaible on December 02, 2009, 03:28:09 PM
I'll give this a shot.
Thanks
Post by: Art Welter on December 02, 2009, 03:34:17 PM
| Adam Schaible wrote on Wed, 02 December 2009 13:28 |
Yeah that's what I thought, I just wasn't sure if there was a better/more accurate way. I'll give this a shot. Thanks |
30|90
35|99
40|108
45|111
50|111
55|111
60|111
Looks like you are probably tuned around 40 HZ.
With a box that big, I'd want to hit a lot lower.
You can cover up part of the port area to lower the tuning for testing. If you do decide you like the lower tuning, you will probably want to extend the port rather than reducing the port area.
Post by: Adam Schaible on December 02, 2009, 07:34:06 PM
I think this is reasonably in line with their spec, -5db at 37hz.
Post by: Art Welter on December 03, 2009, 02:53:08 PM
| Adam Schaible wrote on Wed, 02 December 2009 17:34 |
I believe you are right on the money Art. I put a dab of white-out on the cone, and measured with moderate power (25ish watts) from 20hz and up. The cone stops moving about 40hz. 40 and 41 look the same. It starts to move again but at 65-68hz and up to 100 or so the cone doesn't move much. I didn't measure above 100hz. I think this is reasonably in line with their spec, -5db at 37hz. |
Assuming by “their spec” you are talking about a B2, the B2 in infra mode that Evan posted is flat to 31.5 HZ, looks like -3 dB at 25 HZ.
The B2 is using EQ, but I would doubt they would boost below FB, that would tear the cones up quick like unless they use a lot of frequency dependent limiting, which would limit the LF output to a fairly anemic amount, obviously not the case.
I’d suggest that the B2 tuning is closer to 30 than 40.
But if you are happy only going to 40, your tuning may allow more upper output as long as you HP close to 40.
But again, why have a big box capable of a lower LF corner not get down low?
Everything is a trade off, if you want the max from your box you need to do some higher power excursion tests and see what the best compromise is.
Art Welter
Post by: Pascal Pincosy on December 03, 2009, 03:30:07 PM
As far as the discussion about any 'special' processing being done by the D&B system approach, one could safely assume that such processing is focused on advanced limiting techniques, damping correction, and adjusting alignment to match the rest of their system.
Post by: Adam Schaible on December 03, 2009, 03:43:33 PM
http://www.nordic.dk/_en-GB-II/Content/Data/PDF%20og%20andre %20filer/PDF/Download%20center/Lydafdelingen/B2-SUB.pdf
Check out page 5. The -3db point looks to be 40hz. if I was to use a 40hz LR HP filter, and Fb was 40hz - wouldn't I expect to see -3db at 40hz?
Their curve seems to resemble mine pretty well, although it looks like they cut out some of the increased sensitivity realized in the 55-80hz range.
They do use "sense-drive" - but I don't know any of the specifics around that.
If the box is efficient down to Fb, what would be the point crossing over at 40hz rather than down lower? Probably not the correct way to word it - but if their Fb was lower, wouldn't they crossover lower in normal mode?
All it would take is someone to look down the side ports to see if there's anything going on in there.
The diagrams on page 4 are pretty revealing too.. 30hz looks to be 12db down from 40hz on their curve.
Post by: Art Welter on December 03, 2009, 04:50:55 PM
| Pascal Pincosy wrote on Thu, 03 December 2009 13:30 |
I don't know how Evan made his measurement, but it doesn't jive with D&B's own specs or posted measurements. The B2 manual has a graphic of the response of the B2 that clearly shows that the B2 drops off rapidly below 50Hz, and hits -10dB at 30Hz. The D&B specs state that the B2 is -5dB at 37Hz. And the low corner is the same in normal mode and Infra mode. Perhaps the B2 performs better than specs would indicate, but I very much doubt that. As far as the discussion about any 'special' processing being done by the D&B system approach, one could safely assume that such processing is focused on advanced limiting techniques, damping correction, and adjusting alignment to match the rest of their system. |
Pascal,
Looking at the D&B specs I agree with you.
Looks like Adam's copy is very close to the B2 response.
Post by: Adam Schaible on December 03, 2009, 08:28:32 PM
They describe INFRA mode as a way to increase LF headroom. When you look at the graphs of C-Subs over B2's, you'll see that LF extension IS increased by a solid 10hz and headroom by 12db.
I'm not sure this really requires a 2-box solution though. My cabs frequency response doesn't seem to roll off nearly as sharply above 70hz (at all) as theirs would indicate. I know they want to sell cabs - I'm just not convinced that you need any other cab besides this one. It seems like it handles 40-100 just fine.
I did excursion test with my IT5000HD -3db from clip from 40hz up to 100hz and max excursion was no more than 8mm. I was pretty impressed.
Post by: Jeff Wheeler on December 03, 2009, 09:28:23 PM
| Adam Schaible wrote on Thu, 03 December 2009 19:28 |
It seems like it handles 40-100 just fine. |
I'll just quote from a post I read a few months ago since you seem to be echoing a similar sentiment, at least that's my read of things.
| Doug Fowler wrote on Tue, 16 June 2009 14:17 |
The SP218s go lower. Beach Sound had in their possession the d&b Infra sub just prior to the show and claimed it was a very nice addition to the B2s, just that little extra spice if you needed it. As far as I can tell the 218s and Infras can fill the same role, if you want the SP218s to do that. We chose to do just that, aware of the pitfalls of mixing dissimilar subs. Fortunately the phase response of the two systems was pretty close. The Prodigy had a "20Hz" requirement. We didn't quite make that, but it was good somewhat below 30Hz. During the show we discovered why Jon needs something that can go that low - only a couple of times, but at those times you could tell there was significant program material well below 30Hz. A couple of DJs tested the lower limits as well. I'm a big B2 fan (on the record on PSW multiple times...), but we needed something to go lower. |
Post by: Mark Lonow on December 07, 2009, 08:25:40 PM
i hope evan bringz um out next year
http://www.dbaudio.com/en/systems/j_series/j_infra/
b-2 is bit long in the tooth
its so 2007 get with the times its almost 2010
perhaps a project for adam next summer
Post by: Adam Schaible on December 07, 2009, 08:40:37 PM
Post by: Mark Lonow on December 07, 2009, 11:16:20 PM
about cardioid subs and how to set them up> "processing"
Post by: Adam Kane on December 09, 2009, 12:08:44 PM
Post by: Ivan Beaver on December 09, 2009, 12:52:47 PM
| Adam Kane wrote on Wed, 09 December 2009 12:08 |
I hope Evan never has to move the J-Infra...that thing weighs 335 lbs. I've never heard one...hope I get the chance without having to scoot it any further than a couple feet. |
He has roadies for that
Post by: Adam Schaible on February 21, 2010, 09:54:44 PM
Post by: Duncan McLennan on February 21, 2010, 10:41:22 PM
Post by: Adam Schaible on February 21, 2010, 11:02:09 PM
Post by: Jeff Babcock on February 22, 2010, 10:52:15 AM
Post by: sndguy (Joel Ashcraft) on March 19, 2010, 01:59:41 AM
Joel