Bi-amping speakers, electronic crossovers

[Earthwiz]

I am bi-amping a pair of AL3 plus speakers and need to find a good electronic crossover. Thanks for any help.

[Mudcat]

Behringer, Rane, Samson, ART, and a host of others make very good active crosovers. All have units that operate in multimodes (for lack of a better term) in which you can choose 2-way stereo, 3-way stereo, and 4-way mono. If you just want to seperate the LFE, all you need is a two way stereo.

Prices range from about $150 up to $400. You can find them on eBay, Sweetwater.com, musiciansfriend.com, B&H Photo, etc..

I use two Behringers in my system:

http://www.audioholics.com/forums/showthread.php?t=2380

[Az B]

I also use a Behringer, a DCX2496. One of the big advantages of it is that it also contains a Parametric EQ, as well as digital ins/outs. I run a digital out straight from my Carver Reference CD player, completely bypassing the preamp for digital all the way to the amps for 2 channel.

The Rane is also quite good, although it doesn't come close to the features for the dollar.

[Rip Van Woofer]

Just remember: using an active crossover requires you to play speaker designer to a considerable degree! That means some fairly gnarly measurement with the proper equipment. If you know the crossover point(s) and slope(s) of the passive unit you're replacing with the active, start with those to avoid making things worse.

[FLZapped]

I am bi-amping a pair of AL3 plus speakers and need to find a good electronic crossover. Thanks for any help.


I'm using a Rane AC-22. I needed the delay feature.

-Bruce :D

[Az B]

Just remember: using an active crossover requires you to play speaker designer to a considerable degree! That means some fairly gnarly measurement with the proper equipment. If you know the crossover point(s) and slope(s) of the passive unit you're replacing with the active, start with those to avoid making things worse.

Absolutely! It requires an RTA to adjust and compare various crossover settings, and an oscilliscope is very handy for setting driver delay. (Although it can be done without one)

[Earthwiz]

I have checked on the DCX2496. It looks like it should do the job, but I have a few questions on it's hookup.
It has XLR inputs and outputs. My system has no balanced hookups. Are the adaptors? Also the website said that the DCX2496 has a higher output voltage. Will this be a problem?
My system includes;
B&K Reference 20
Carver AV 806x
Parasound HCA 1200
The passive crossover point of the Carver AL-III plus is 150hz. I do have an titanium Eclipes 12" sub on the LFE channel off the B&K set at 80hz. I have been told that the AL-III's go down to 30hz but begins to fall off starting at 40hz. The Reference 20's LFE is fixed and I would like to know if this DCX2496 would run a sub output plus the 2 channels out. I would like to drop the sub down a little bit as I seem to still be able to locate it.
Thanks again for any help.

[Az B]

I have checked on the DCX2496. It looks like it should do the job, but I have a few questions on it's hookup.
It has XLR inputs and outputs. My system has no balanced hookups. Are the adaptors?


Yes, you can either make them very simply or you can buy them at a pro audio store. If you want to make them, you basically attach both the negative and shield cables of the XLR connector to the ring of the RCA connector on the opposite end. Plus is the tip. There are instructions in the DCX manual with pictures.



Also the website said that the DCX2496 has a higher output voltage. Will this be a problem?.


It helps if your amps have gain controls, but you can always adjust the gain internally in the DCX.


The Reference 20's LFE is fixed and I would like to know if this DCX2496 would run a sub output plus the 2 channels out. I would like to drop the sub down a little bit as I seem to still be able to locate it.
Thanks again for any help.

You have six channels of outputs. That means two for low frequency drivers, two for the ribbons, and two left over for stereo sub or whatever. They are completely mappable and mixable. That should give you far more flexible bass management for your sub. Set the reciever to the highest setting and let the DCX do the work.

Keep in mind that you will need an RTA. TrueRTA is a good, inexpensive choice. Behringer makes a great calibrated mic that you can pick up at a pro audio store for about $40. Do not attempt this with anything but a calibrated mic.

You will also need to rewire your speakers. The passive crossover will need to be bypassed.

Expect to spend at least a couple days completing this project, and maybe more for tweaking. The results will be worth it; for one thing, you will need half the amplifier power for the ribbons to reach the same SPL as before. Since they're not particularly efficient, this is a very nice benefit.

[Earthwiz]

Thanks for all the help so far, but of course I still have a few questions.
On the AL-IIIs, the crossovers have be replaced once before by Carver as I had done in a capacitor. They installed beefier ones after the second crossover died about a month later. It seems I might listen to them too loud for too long and they heat up. Thats' what the tech said anyway. Now about a year and a half later the speakers are acting up again. I can only turn up the throttle about a quater and the protection comes on from the amp. I have swapped amps and it is the same. Both speakers are causing this to happen. The fuses in the speakers will blow first, and then swapping out for larger values (I know, not right) the protection from the amp comes on. I am wondering what might have died. I am hopeing that it is in the crossovers and not the drivers. The drivers play normally until the fuse pops and it is only the woofer fuse that goes. The ribbons seems fine and will play up to "my" normal listening levels. The sub hides the fact that the woofer fuses blow. The sub is crossed over to high as it has no filters in it, it is just off the LFE of the B&K at 80hz. When I pulled out the crossovers, one of the coils had come unglued from their base which had a capacitor glued to the top. Each crossover, same thing. The coils were checked and not shorting. The caps were not swelled or ends blown out. Nothing looked burnt. It is a couple hundred each and up, depending on whats blown, and a trip to Florida to the place Carver has told me that fixes the AL-III+.
I have given this information for background to my questions. First, I do not know how to test a crossover and I do not know if this can be done with just a volt meter. Next, I do not know much about ribbon tweeters other than they a very directional, somewhat inefficient and do not last long. From what I just explained, does it sound like the crossovers or the ribbons? This would dictate if I bi-amp or do some more shopping. I would hate to give up on these speakers as I think the sound great.

[Rip Van Woofer]

My not-very-educated guess is that the caps in your xover are being overtaxed, even if they haven't blown (the dielectric is prematurely breaking down due to high voltages). My other guess is the resistors (they're getting too hot). Either way, they might not have a high enough voltage (watts in the case of the resistors) rating for your amp and/or listening levels. More knowledgable people here may have other ideas.

Or there is a wiring fault in the crossovers, or an intermittent short elsewhere in the chain.

Rather than futz around with beefing up the current passive crossovers, get the Behringer or another active unit. Active units install before the amps so you can't blow the crossover. Then if you're still blowing speaker and amp fuses, you know it's another problem! And of course there are the purely sonic benefits of the active unit.

Of course, the question I really have is: Holy guacamole! What the #@$%! are you driving them with and just how loud do you listen!?! :eek:

BTW: The ribbon driver maker Bohlender-Graebner makes replacement ribbons for the Carver "Amazing" and might have suitable replacements for the AL-3, too. Check them out. Parts Express carries them, for one.

[Az B]

There are two possibilities that I can think of. One is that your xovers are not up to the voltage you're sending them, and the other is that these speakers are notoriously hard to drive and can have nominal impedances well into the 1 ohm range. This is hard for many amps.

Either way, the active xover will help. It will make the drivers twice as loud with the same power, which reduces the amount of power needed for any given volume, and it takes that whole heat building, inefficient passive network out of the picture.

Please remember that you'll need a lot of tweaking to get it right with the active xovers. You'll need some EQ to flatten out the response of those ribbons. Normally, the passive xover is designed to deal with phase issues and less than linear response, so by eliminating the passive xover, you'll need to do this yourself. It's not for the faint of heart.

[mtrycrafts]

I am bi-amping a pair of AL3 plus speakers and need to find a good electronic crossover. Thanks for any help.


Just in case Rip Van's comment was not clear to you, you do need to bypass the passive crossover in the speaker system if you use active crossover.

[Earthwiz]

Thank you for the info.
These speakers are powered by a Parasound HCA 1200-II @200w rms @8 ohms for the ribbons and a Carver AV806X 6 channel with 2 channels running the woofers at 130w rms @ 8 ohms. The speakers are rated at 4 ohms. I rarely go over 100dbs.

[Earthwiz]

Just in case Rip Van's comment was not clear to you, you do need to bypass the passive crossover in the speaker system if you use active crossover.
Thank you. I understand that they need to be bypassed. I will solder the speaker leads direct to the binding posts, clipping out the crossover network. They are already bi-wireable so I have both ribbon and woofer hookups.

[Earthwiz]

Please remember that you'll need a lot of tweaking to get it right with the active xovers. You'll need some EQ to flatten out the response of those ribbons. Normally, the passive xover is designed to deal with phase issues and less than linear response, so by eliminating the passive xover, you'll need to do this yourself. It's not for the faint of heart.

This is the part that worries me. My sound card in my computer does have digital in/out and normal analog hookups. I looked at the TrueRTA online and this seems alittle complicated. Do I need the whole TrueRTA package for $99 or just the free part that is downloadable. I am not sure what tests I need to run.
Also, I hope that I do not wear out my welcome with all these questions and more to come when I start to tweak the ribbons.
Thanks.

[Az B]

This is the part that worries me. My sound card in my computer does have digital in/out and normal analog hookups. I looked at the TrueRTA online and this seems alittle complicated. Do I need the whole TrueRTA package for $99 or just the free part that is downloadable. I am not sure what tests I need to run.
Also, I hope that I do not wear out my welcome with all these questions and more to come when I start to tweak the ribbons.
Thanks.

As long as you're worried! I was worried that you weren't worried enough, and that is worrying...

I guess the big thing here is to make sure you can hook the passive xovers back up later in case there's a problem. Take pictures, label wires, make diagrams... whatever you have to do. If you just cut and run, you won't be able to turn back and you may regret that.

I would really recommend the Behringer DCX2496 at this point as it has multiple curve types and slopes available at the push of a button. It also has some parametric EQ, which you will need. In a worst case scenario, you may need another outboard EQ.

The goal is flat frequency response in the room. Usually the first thing people use this stuff for is to tune for bass modes. But first, you need to get the crossover freuquncies flat. This will likely take some experimenting, but you already know the crossover points, so it'll be mostly experimenting with the filter types and slopes. The problem is that drivers interact in some very strange ways in the general area where they cross. An additional hurdle is that ribbons tend to be less than flat to begin with and need a fair amount of EQ (typically engineered into the passive xover) to get flat.

This is where the RTA comes in. It will demonstrate to you in real time, exactly what effect any changes you make in xover type, slope, or EQ have on the actual output of the speakers.

This will not be easy, and it will take time. If you're the kind of person that has a hard time understanding graphs or doesn't have the patience to finish a crossword puzzle, you might want to try a different approach. If you hurry it, it will suck.

The good news? If you have the patience and are stupid enoug... I mean brave enough to try this, you'll have speakers that are more efficient and flat to your room. This is a big deal, especially considering that these speakers are very inefficient, and very few audiophiles have actually achieved a flat in room response with any speaker.

[Earthwiz]

Thanks for the words of encouragement, I think? I do have a eq/spectrum analyzer in my system with a pink noise generator and mic. I have set the room flat according to it and then tweeked it to my liking. But most of the time it is off and I listen through digital inputs and the eq is analog.
On a non musical note, is there a spell check in this board?