Active crossover / sub out Q

**BoomieMCT** · **12-13-07, 11:00 PM**

Does anyone know of any active crossover (or EQ) that has a subwoofer output which highpasses the mains (not just lowpass the sub)? It sounds like the Behringer and ART crossovers on PE have no highpass. If I have a sub I really don't want to bother my mains with the LF.

**Anthony** · **12-14-07, 07:32 AM**

My old NHT SA-2 amp has such a crossover. I believe it is 3 position adjustable for signal level, and fixed 120Hz high pass for the speaker level inputs.

Aside from lack of power, it is a very capable sub amp in that regard. One of the first designed to drive a passive sub (and have the built-in crossover). At the time all that was available was plate amps or regular amps (you supplied the crossover).

MCM has kits that have that kind of control. Also check out the plate amps at Madisound, I believe they are slightly different than the PE ones.

**BoomieMCT** · **12-14-07, 07:38 AM**

Thanks Tony, but I'm looking for just a crossover, not an amp with a crossover.

I guess a little backstory is in order. This is part of yet another project to get my wife's new band equipped. The PA mains I made work great. I'm a little worried they won't be up to the task of outdoor gigs. I think that adding a sub to take the low frequencies off the mains will work well towards this goal. The problem is that all the active crossovers I can find are only lowpass for the subwoofer output but pass full signal for the main channels. I know I could just make a passive highpass for the mains but I'd like to do this actively if possible (to not waste power).

**Anthony** · **12-14-07, 07:41 AM**

I'm sorry, not MCM, but Marchand electronics

http://www.marchandelec.com/xovers.html

**BoomieMCT** · **12-14-07, 08:14 AM**

That XM9 is nice (and so far the only thing that does the job), but the *kit* is $350! For that extra money I'd just buy a self-powered sub and be done with it.

However, this does give me an idea. Maybe I'll try making a fixed 100 Hz active x-over. That should cost less and be more efficient than a passive one with huge caps and inductors.

**JCD** · **12-14-07, 05:22 PM**

How about this one -- Rane SAC23
Granted this one is ~$300, but the SAC22 can be had for $215 if you have a two way plus sub.

Or what about any other 3 way crossover? Like a Behringer CX3400 or a Rane AC23 or an Ashly 2001? Again, assuming you only have a 2 way regular speaker.

JCD

**brent_s** · **12-14-07, 05:48 PM**

Boom, are you looking for a mono lowpass only? If not, it looks like the ART 310 and Behringer CX3400 have low enough 2-way crossover points to be useful.

I've also got a Marchand XM9 sitting in the attic gathering dust that I could probably be persuaded to part with.

-Brent

**BoomieMCT** · **12-14-07, 10:55 PM**

Quote:

JCD wrote:

How about this one -- Rane SAC23
Granted this one is ~$300, but the SAC22 can be had for $215 if you have a two way plus sub.

Or what about any other 3 way crossover? Like a Behringer CX3400 or a Rane AC23 or an Ashly 2001? Again, assuming you only have a 2 way regular speaker.

JCD

Quote:

brent_s wrote:

Boom, are you looking for a mono lowpass only? If not, it looks like the ART 310 and Behringer CX3400 have low enough 2-way crossover points to be useful.

I've also got a Marchand XM9 sitting in the attic gathering dust that I could probably be persuaded to part with.

-Brent

Quote:

JCD wrote:

How about this one -- Rane SAC23
Granted this one is ~$300, but the SAC22 can be had for $215 if you have a two way plus sub.

Or what about any other 3 way crossover? Like a Behringer CX3400 or a Rane AC23 or an Ashly 2001? Again, assuming you only have a 2 way regular speaker.

JCD

The problem with the Behringer and ART EQ and crossover products is that they are low-pass only. The mains still get sent a full signal. If I'm going to be driving these speakers hard I want some highpass action on the mains as well. I also don't want to spend $300+ to get it. For that price I'd abandon DIY and get a decent self-powered sub with a proper crossover. I'll have to do more research into Rane and Marchand.

If anyone knows good information sources so I can make my own active crossover I'd be much appreciated.

**F1 fan** · **12-16-07, 03:06 PM**

Quote:

BoomieMCT wrote:

The problem with the Behringer and ART EQ and crossover products is that they are low-pass only. The mains still get sent a full signal. If I'm going to be driving these speakers hard I want some highpass action on the mains as well.

The Behringer CX2310 and CX3400 both do have low and hi pass outputs and can be had for approx $100-130.

Quote:

If anyone knows good information sources so I can make my own active crossover I'd be much appreciated.

Do you want to build from scratch onto a perf board or purchase a PCB for the purpose.I have done it both ways and not surprisingly prefer buying blank pre made boards.It is a bit more costly but it is worth it.My first choice of PCB would be the MT1 from Linkwitz. http://www.linkwitzlab.com/pcb.htm#MT1.Others have mentioned Marchand and they have several suitable blank boards as well.Keep in mind by the time you add up the cost of the board,op amps, caps ,resistors and power supply and chassis etc.you may have spent more than it would cost for a CX2310.

**BoomieMCT** · **12-16-07, 03:12 PM**

[quote=F1 fan;67546]The Behringer CX2310 and CX3400 both do have low and hi pass outputs and can be had for approx $100-130.

Are you sure about this? I wrote Behringer and the (not incredibly clear) response I got seemed to indicate the mains got sent a full signal even with the sub x-over on.

If you are right, that is great! BTW, since you have more familiarity with this product then I, do you know if you can send a full signal to the mains? I don't want to have to biamp the mains . . . yet.

**F1 fan** · **12-16-07, 03:24 PM**

Do you not have separate amps for the mains and sub?As that is the only way an active setup can work.

**brent_s** · **12-16-07, 06:45 PM**

Give these Projects a read.

**BoomieMCT** · **12-16-07, 11:16 PM**

Quote:

F1 fan wrote:

Do you not have separate amps for the mains and sub?As that is the only way an active setup can work.

I have seperates for the main and sub, but the mains are not bi-amped. Does the CX2310 have a way to send signals to a sub and mains or do the mains have to be bi-amped?

**Ricci** · **12-17-07, 11:58 AM**

If you want a truly flexible crossover you should look at the Behringer DCX2496. It should be completely overkill for what you are doing, and also has some Eq'ing abilities built in. They usually go for about $250 or less on Flea-bay.

**BoomieMCT** · **12-17-07, 12:48 PM**

Quote:

Ricci wrote:

If you want a truly flexible crossover you should look at the Behringer DCX2496. It should be completely overkill for what you are doing, and also has some Eq'ing abilities built in. They usually go for about $250 or less on Flea-bay.

That is overkill! Actually the Behringer 15 band stereo EQ with sub out would be perfect IF it actually cut the sub frequencies to the mains (it does not).

**F1 fan** · **12-17-07, 05:31 PM**

Quote:

BoomieMCT wrote:

I have seperates for the main and sub, but the mains are not bi-amped. Does the CX2310 have a way to send signals to a sub and mains or do the mains have to be bi-amped?

If you connect the hi pass outputs of the crossover to the amp driving the mains, then the entire frequency range above the selected crossover point will be reproduced by the mains.There is no need to bi amp them.For the subs you will use the low pass outputs or the dedicated sub output.

**JCD** · **12-17-07, 07:22 PM**

Looking at page 7 of Behringer CX2310 manual found on this page, it looks like the [10] governs the subwoofer crossover that limits both the subwoofer high output as well as the low signal (ie, the woofer/mid). This assumes you are going completely active with your system. If you just need the sub signal cut out of the main l/r signal, than going with F1's suggestion would be the way to go.

Anyway, that particular crossover is ~$90.

JCD

**F1 fan** · **12-17-07, 07:49 PM**

Quote:

JCD wrote:

Anyway, that particular crossover is ~$90.

I don't know how they can sell it for that and still turn a profit.

**BoomieMCT** · **12-18-07, 06:17 AM**

Quote:

F1 fan wrote:

If you connect the hi pass outputs of the crossover to the amp driving the mains, then the entire frequency range above the selected crossover point will be reproduced by the mains.There is no need to bi amp them.For the subs you will use the low pass outputs or the dedicated sub output.

This is my question. In stereo mode there are two outputs other than the sub out. Stereo high (rear 1), stereo low (rear 2). If you had mains you didn't want to bi-amp would you just connect to the high outputs (rear 1) and turn the stereo crossover (front 3) really low? Can you make that crossover lower than the sub x-over?

**Anthony** · **12-18-07, 11:33 AM**

Here's my interpretation of this:

Wire up the mains as high pass in Stereo 2 way mode. Leave low empty.

For full range mode, turn the crossover all the way down (44 Hz).

For subwoofer mode, turn the crossover up to 80 Hz or so, and wire up the subwoofer to the sub out.

Based on what I saw, there is no high pass cross related to the subwoofer setting. It was just a subwoofer cut in stereo 2 way mode (a low pass only filter)

So you wouldn't be able to just push a button to configure it for sub operation, but you could have it so you just adjusted a couple of knobs to make everything happen.

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