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Title: 2 15 with 2 inch horn or quasi three way
Post by: brad smith on August 24, 2004, 09:47:29 am
System consists of Peavey DTH 4215 and DTH 218 subs ran stereo three way with GPS 1500for the highs, GPS 3500 mids, and 2 GPS 2600 bridged for the lows through a TDM crossover. I was wanting some advice from people that know more than I do. Here's the question. Should I rewire the cabinet to make it a REAL bi amped cabinet by replacing the 4215 speaker plate and putting in a new speakon plug and have it wired only for a bi amp signal instead of the way Peavey designed it as a quasi three way. I was thinking of making it more like a JBL SR 4733 with the two 15's and the horn. I'm just really curious as to what other people have to say about the setup and what they would do. We play mostly small to mid sized clubs with the occasional outdoor show. This month were out side three times and I just want some opinions.

Thanks,

Brad
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: Dave Rickard on August 24, 2004, 10:59:05 am
http://www.peavey.com/media/pdf/misc/addingasub.pdf

is the web address for a .pdf article by Peavey that addresses this, in part.

If the link doesn't work, go to Peavey.com and click on "tech notes",  there is a list of articles there.

daver
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: brad smith on August 25, 2004, 09:41:48 am
Would anyone try to rewire the cabinet or keep it the same way it is designed? I've read the article in the tech notes and am still not what I should do. I bought the system at a great price and I'm not 100% satisfied with the sound that is coming out of the system. Please give me some advice as what you would do. I would have preferred to buy a JBL 4733-4719 combination but I couldn't afford that system so I bought the DTH 4215-218 rig that has the quasi three way set up in the top cab. PLEASE give me your opinions on what you would do.

Thanks,

Brad
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: Dave Rickard on August 25, 2004, 02:53:42 pm
Brad,

Help me under stand your setup and I'll take a stab at it.

Are you running a 3-way crossover?  When you say 3-way is the horn receive it's own separate signal, and the DTH woof section is getting the mid band pass?  The real question: Do you any hi-pass on the woofer section of the DTH?  What are your crossover points?

daver
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: yam4000vca Jim Gould on August 25, 2004, 05:42:58 pm
I will take a stab at this and I have not read the Peavey article so I could be missing something.
If you are all the time running this system with the subs I do not see any reason to make the top box run quasi 3 way.
Here is where the problem may be though by eliminating the Peavey cross over all together and going straight to the 15s and the horn.
There is a pretty good chance that there is more going on in that passive cross over for the hi end than you may be aware of. By bypassing that the results would be fine for the 15s I think but maybe create a problem that would give you less than the best result on the high end.
Depending on what kind of speaker management system you may have you could possibly get information from Peavey on what can be done.
Another option is to put the hi end through the passive any way. You are not going to loose much with the hi end going through that and whatever adjustments that are made there for the hi end you would still have.
In this way all you need to do is add another speakon for the 15s. Keep everything intact so if you wanted to run the box full range you could as well as having it factory if you decide to sell it down the road.
I have run other Peavey systems for people and that is the way I have done it. It seems I do recall something going on in that network that needs to stay there. Of course if you have the processing ability there are proably other ways.
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: Dave Rickard on August 25, 2004, 06:46:38 pm
Hi Jim,

As I understand this series, the DTH4215 cab is actually a 2.5 way system with a horn (separately biampable), and a 15 linked to another "sub" 15 which has a (hard-wired, non-bypassable) first order LP inductor @ 200 Hz.

So, if Brad is using a 3-way crossover prior to the amps and sending the mids and highs to the 4215's, he has eliminated that second "sub only" 15 by HP-ing before the LP.  The article says add subs to this system by sending full range to the 4215 and only LP-ing your subs.  For biamp operation *only the horn* is separated, so a midband to the 15's still eliminates that second "sub" woof.

Brad,

Is this what you are doing?  Does any of this make sense?

Dave
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: Mike MacWillie on August 25, 2004, 07:43:53 pm
I believe what he wants to do is remove that inductor, and have the two 15's running the same frequency range. I don't see why it isnt possible.. Not sure what the response would be like though.
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: brad smith on August 25, 2004, 09:24:34 pm
I'm using a TDM crossover crossing over at about 150 and 1800 if I remember right. Everything is cased up and in the trailer. I'll know for sure where at Friday night. Peavey responded to my question about the crossover question. When it is bi amped there is still an inductor in line with the bottom 15 so it is a quasi three way when either bi amped or ran full range. I talked to a guy that does regional sound using a JBL 4733-4719 rig several cabs and he suggested the idea of switching the wiring. I'm ready to try something else. Anybody know where I can get a speaker plate that will mount on the back of that cab. Peavey told me that they did not have any left. Back to the rig. Ran three way with three different signals with the crossover. I sometimes feel that I'm not getting the most of that system and am ready to try anything. HELP ME PLEASE> I really appreciate the opinions. One of the best ways to learn. Also, what kick drum setting does anyone suggest for a D4. Currently using the fusion tuned all the way down.

Thanks again, this is a great tool for people like me,

Brad
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: Mac Kerr on August 25, 2004, 10:36:37 pm
The tech paper that daver posted the link to explains pretty clearly why should not remove the inductor on the second 15" driver. It also explains why you should not cross over to a real sub at a frequency as high as 150Hz. The inductor is there to roll out one of the 15's above 300Hz where there would start to be a lot of comb filtering in the mids because of the adjacent drivers. This same technique is used in the Meyer line arrays.

The paper also explains that if you cross over to subs at 150 as you have, you are only using the double 15's from 150-300Hz as 1 of them rolls out at 300 for the reason explained above. If you low pass your subs at 85-90Hz and let you DTH-4's run with no high pass on the 15's, or high passed at 40Hz you will be getting almost 2 more octaves out of the double 15's, and your subs will only be working at real "sub" frequencies. You should have more low end this way, and still avoid the comb filtering by letting one of the 15's go away at midrange frequencies.

Since from your description you have not yet tried the manufacturer's recommended method for setting up these speakers, you should give that a try before you modify the speakers with possibly detrimental results.

Mac Kerr
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: yam4000vca Jim Gould on August 25, 2004, 11:27:34 pm
I am understanding of the way the box is to work in its factory setup.
My idea was basically to just turn it into a standard dual 15 box when being used with subs.
As far as any comb filtering going on between the 15s in that box I am sure some of that exists but myself and many others have run dual 15 boxes(I use a dual 15 on the lower mid on a 4way system now)and notice no terrible results from it.
I was more concerned about things that could be being done to the high end than worrying about the 15s.
In this case I think I would cross them over lower than 150hz. I think 100hz would be good. I would also go a bit lower between the horn and the 15s. 1800hz seems a bit high to me with 15s.I think I would try between 1200hz and 1600hz there.
As usual the ear has to be the final judge of all this.
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: Marjan Milosevic on August 26, 2004, 07:32:36 am
If I were You I would stay with curent crossover point of 1800Hz.
Lowering this, will result in lower power handling of the 2" driver and greater heat dissipation and can also make the driver sounding too harsh.

I would realy drive it full range as they are.

Just my 2 cents.

Regards
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: yam4000vca Jim Gould on August 26, 2004, 08:54:12 am
I am not sure if you are aware but Peavey has systems that have in the past been set up to run the ancestors of this very driver crossed over as low as 600hz. This is an improved version with ferro fluid and I can expect it would easily handle being crossed over at 1200hz with no problem at all in real world useage.
What it sounds like of course is a matter of taste and how much eq you may need to put on it to make it sound the way you want.
Over the years when configuring many systems,Peavey among them, I have never taken 15s up to 1800hz. I have done it with 12s and 10s even higher.
Another point I would like to make is that I am of the school of thought that these are 1in drivers.
The orginal post was asking about rewiring it and that is what I spoke to. I also think it may be better off run as designed possibly but I suggested a way to set it up with out tampering with the way it was designed.
If the person does that they try running the top box biamped   and use thier ears and decide if it is better for them.
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: Dave Rickard on August 26, 2004, 09:33:06 am
It's their 4inch VC driver on a 2inch exit horn.  

I've seen Peavey cross these at 800Hz in another cabinet and I thought they sounded fine.  They rated the cabinet @ 450w RMS.
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: Dave Rickard on August 26, 2004, 09:49:48 am
I agree with Mac.  

You have not yet heard what your system can do.  Therefore, don't rewire, *yet*.  Run full range (or 40Hz HP) to the 4215's and only LP filter to your subs around 80-100Hz.  I assume you are unhappy with your bass power capability.  This may shock you with what you've been missing...

You described low passing the 4215's at 150Hz (I assume 24db/oct.), and then the internal inductor high passes that second woofer @ 200Hz (6db/oct), effectively *reducing* the cabinet to a single 15 design.  The band pass on the woofer is from 150-200Hz!

If you are set on modifying, partsexpress.com can supply your parts.  But if I were you, I would want to know what I had on my hands first.

daver
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: yam4000vca Jim Gould on August 26, 2004, 09:57:44 am
I will admit a mistake. I went to Peavey web site to try and confirm what these dth cabinets were about but seems they are not there. At least I could not find them.
I did have first hand experience with a different 2x15 horn Peavey cabinet that ran quasi 3 way. This had the smaller driver on the high end.
Sorry for any mis-information
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: brad smith on August 26, 2004, 11:55:51 am
You can find the cabinet specs on the peavey site. Go to support and search for manuals. It's the DTH 4215, it comes up in pdf format. All the help is GREATLY appreciated. Stupid ????. How do you high pass at 40hz the tops
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: Dave Dermont on August 26, 2004, 12:44:42 pm
First of all, the inductor on the bottom woofer is a LOW PASS FILTER and is used to take excess midrange frequencies out of the lower 15" driver.

Taking the inductor away might be a good idea if you're using the TDM active crossover. I also might give you a huge couple-three octave wide hump centered around 300Hz-400Hz or so. If the hump is not too big, you can use the TDM's mid level and the FOH EQ to get it under control.  

Check to see if the 15" drivers are the same model too. The driver with the inductor may be different, as it's not intended to go up as high as the other 15" in the cabinet.

As you can see, making changes like these can open up many different cans of worms. I like to leave speaker designing to speaker designers.

Many old-timers hate passive components on their drivers because it eats up amp power to some extent. This is a throwback to the old days when "big" amps delivered 350 watts or so per side, and guys were trying to squeeze every last dB they could.

Now a days, a passive box and a big honkin' amp can sound really good, AND be loud too.

What you want to do may improve your rig, but it could turn it into an expensive pile of firewood too. Document the changes you make, and keep your passive crossovers around so you can change things back it you need to. Do it when you have lots of time to tweak and listen. Don't do it at a gig.

Another idea is to get another GPS3500. Use it along with the one you have for subs, and move the 2600's to mids. The one 1500 should still be enough for highs. This, of course, is a more expensive solution.

Keep us posted as to your progress
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: Dave Rickard on August 26, 2004, 03:36:28 pm
bsmith wrote on Thu, 26 August 2004 16:55

How do you high pass at 40hz the tops

I don't think the TDM crossover can do that.  Just run your 4215's full range, and use the crossover to LP your subs around 80-100Hz.

Let us know what you find out.

daver
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: Ronnie Blenden on August 26, 2004, 06:29:37 pm
O.K.  I have been involved in the usage and sales of many peavey products.  All their 2x15 cabs are wired quasi three way.  Most people buy a sub to throw under it when the bottom is not enough.   When using a three way crossover and setting the low(or sub) crossover point around 100-150 then you are basically eliminating the bottm 15 in the cabinet and replacing it with the sub speaker. In quasi three way both 15" speakers get the low frequency bass.  The upper one gets mids and bass with the lower one crossed over somewhere in the 150-250 range.  You do not get the impression of added bass when simply adding a sub and using a three way crossover.  You will get your best results by far by doing one of two things.  Either get rid of your crossover and get something like a BBE Sonic Maximizer with a sub out or rip all the guts out of the DTH and rewire the two 15" together for a dual mid situation.  The BBE (or comparable) works really good if you are just the weekend warrior.  You can run stereo full range in from the mixer, full range out to the amp or amps for the dth's and then use the sub out which has a separate gain control to send to a sub amp then on to your sub cabinets.  You simply set up the PA with the sub control turned down.  Get the volume level and sound you like and then turn the sub gain control up until you get the amount of thump you want.  Very, Very, simple.  No worrying about crossover frequencies.  You will cause no harm though if you decide to do away with the internal crossover and wire the 15's together.  If you order JBL's set up for tri amp usage from the factory that is how they are done.  No crossover, just a panel with two nuetrik 8 conductors for mid, high, and a sub passthrough so you can send one 8 conductor cable for each stack.  Hope this is what you were looking for.
Of course, by ripping out the passive crossover you will be violating the warranty on the cabinets.  In that case you might want to build another panel so that way you can keep all the guts and put them back in stock if you need to.  Razz
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: Dave Dermont on August 27, 2004, 10:14:43 am
captainjack wrote on Thu, 26 August 2004 17:29

  You will get your best results by far by doing one of two things.  Either get rid of your crossover and get something like a BBE Sonic Maximizer with a sub out or rip all the guts out of the DTH and rewire the two 15" together for a dual mid situation.  The BBE (or comparable) works really good if you are just the weekend warrior.  You can run stereo full range in from the mixer, full range out to the amp or amps for the dth's and then use the sub out which has a separate gain control to send to a sub amp then on to your sub cabinets.  You simply set up the PA with the sub control turned down.  Get the volume level and sound you like and then turn the sub gain control up until you get the amount of thump you want.  Very, Very, simple.  


Yes, very very simple, and also very very ghetto.

The TDM analog crossover, a relativly low-cost piece of pro gear, and a regional sound reinforcement workhorse, offers near legendary performance.

At best, the Sonic Maximizer is a marginal piece of audio snake oil, and a BIG step backwards from the TDM.
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: brad smith on August 27, 2004, 11:38:17 am
And to add to all the craziness as what i should do, I remembered the CEX that I bought that has been out of the loop. Should I hook that up and run bi amp stereo versus three way mono. I had troubled when I hooked up the CEX with the settings. I programmed the unit for the DTH 4215/218 rig but was real unsure as to some of the settings like the DBV value for the GPS amps. GPS 1500, GPS 3500 , and GPS 2600's. I did not have enough time to really work out the kinks on my own so I unracked the CEX and went back to analog. Should I run an EQ with the CEX or just go CRAZY.  I'm planning on lowering the crossover to about 80-100 for the lows and still triamp to see what happens , but I figure that if I can get the CEX to work right with my rig that would be the best deal. I also have a REAL sound eng. LOcal guy coming to help spec everything out when he can foot me into his schedule.

Sorry for the length,

Brad
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: Dave Rickard on August 27, 2004, 01:50:58 pm
Brad,

The CEX changes things a bit.  I haven't worked with that exact unit, so I'll try and stay out of trouble by being general, and hope others will correct me if I'm wrong.

1.  The 4215's are -3dB @50 Hz, and -10dB @ 36Hz.  So send your signal to the CEX, set one set of outputs to HP filter @ 36-40Hz and feed this to the 4215 amp(s).  The box is tuned to 48Hz, so you may have excursion/distortion issues, at high power, below 48Hz.  Only you can answer this.

2.  Set another set of outputs to LP around 80-100Hz (to taste) and run this to your sub amp(s).

With the main EQ flat, adjust the output of the two sections to balance the subs and mains.  Then, add your EQ to correct or enhance.

Any other opinions?

daver

Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: Mac Kerr on August 27, 2004, 02:43:40 pm
I think the CEX is only a stereo biamp processor. I could be wrong, I have never seen one. If it is, by all means use the CEX to process your DTH4215's as stereo biamp using the factory presets that are available for download on the Peavey website, and use your TDM to create a sub feed with a 35Hz HPF and an 80--90Hz LPF. The input to the TDM can be the same full range signal that goes to the CEX if you want to run the whole system as a stereo triamp, or it could be a feed from an aux send if you want to go to aux fed subs. If you have the amps available this would be the way I would go.

Mac Kerr
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: Ronnie Blenden on August 27, 2004, 04:51:41 pm
Yes, "anotherdave" it may not be as pro or even anywhere near pro, but if you would refer to the original post it was never mentioned that this was for any touring or production company.  Only a group that plays small to medium clubs with the occasional outside gig.  Lighten up people!!!
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: Dave Rickard on August 27, 2004, 07:08:14 pm
I would amend my post to agree with Mac.  I forgot you can biamp the 4215's (duh!).  Just don't filter out the lows from the woofers, unless you can place the HP filter around 40 Hz.

Balancing your response with the crossovers as much as possible should still be done prior to EQing.

daver
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: Douglas R. Allen on August 27, 2004, 07:26:54 pm
bsmith wrote on Fri, 27 August 2004 11:38

And to add to all the craziness as what i should do, I remembered the CEX that I bought that has been out of the loop. Should I hook that up and run bi amp stereo versus three way mono. I had troubled when I hooked up the CEX with the settings. I programmed the unit for the DTH 4215/218 rig but was real unsure as to some of the settings like the DBV value for the GPS amps. GPS 1500, GPS 3500 , and GPS 2600's. I did not have enough time to really work out the kinks on my own so I unracked the CEX and went back to analog. Should I run an EQ with the CEX or just go CRAZY.  I'm planning on lowering the crossover to about 80-100 for the lows and still triamp to see what happens , but I figure that if I can get the CEX to work right with my rig that would be the best deal. I also have a REAL sound eng. LOcal guy coming to help spec everything out when he can foot me into his schedule.

Sorry for the length,

Brad


Hello
I have 3 cex's and have spent allot of time with them.
I have a dth218b Qw 1 rig as well as some SP1g's as well.

Unless you have access to smaart,tef etc I would not recommend having the tops full range with added subs. The box tunings are different. Also removing the inductor will cause cancellation problems because of the distance the two 15's centers are apart.

The Cex will go 2 way stereo A-B. 3 way with the 4th output from B in. 4 way mono. As well as delay lines with the input delay of 650 ms being placed on the outputs.

The gps 3500 is 4.5 dbv.
I can check the rest if you need it. The peavey settings should get you close.
I do have some smaart outside, cex settings for the horns and subs but your mids are different.

Where do you hail from?

Doug
Title: Re: 2 15 with 2 inch horn or quasi three way
Post by: Travis Valois on September 01, 2004, 02:23:41 pm
By wiring the 2 15's in parallel you may end up with comb filtering issues throught he midrange band.  The double 15 cabs we use at one of the clubs I do some work in has this issue.  An abusive DJ blew one of the 15's and the midrange with the one dead speaker in the cabinet was much better that the cab with 2 working 15's.  

This does not appear to be as much an issue with double 12" cabs.