# DCX Electronic Crossover and Bi/Tri amping



## Anthony (Oct 5, 2006)

As a way to speed up my prototyping, I was thinking about getting a DCX2496 electronic crossover and bi/triamping speakers.

If nothing else, it would be fun to play with. 

I had a few questions for owner or just bi/tri amp people in general>

1) Bi or triamp a three way? Based on available amplification, I would need to only biamp the MTM section of my current prototype and then run the woofers separate. Would it be worth the expense to add another amp for the mids?

2) What are some good low wattage amps for mid/tweet applications? I have a nice outlaw 1050? 5 ch amp which would be way overkill for anything but woofers. Sadly, most of the 40W multichannels I find are for ceiling speakers or office PA stuff. Not really audiophile quality.

3) How many filters can this unit do before becoming saturated? I notice that it does not say how many filters per channel, only that they all use a certain amount of processor and when you run out, you have to trade off. What are we talking, 30 filters total? 60? 10?

I'm sure I'll have more questions, but for now that will do to start. 

Thanks,
Anthony


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## Wayne A. Pflughaupt (Apr 13, 2006)

I think can help with a couple of these.


> 1) Bi or triamp a three way? Based on available amplification, I would need to only biamp the MTM section of my current prototype and then run the woofers separate. Would it be worth the expense to add another amp for the mids?


Seems to me if you want to go active, then go all the way. Seems pointless to me to do a combination active/passive speaker.



> 2) What are some good low wattage amps for mid/tweet applications? I have a nice outlaw 1050? 5 ch amp which would be way overkill for anything but woofers. Sadly, most of the 40W multichannels I find are for ceiling speakers or office PA stuff. Not really audiophile quality.


As you probably already know, if you’re doing an active system you can get away with using lower-powered amps, as passive crossovers soak up a lot of power.

I’ve toyed with the idea for years of bi-amping my front speakers. The amps I would use aren’t in production anymore, so you’d have to find them on eBay. Back in the 90s Yamaha made a nice little 4-channel amp with I think 30-40 watts per channel. Adcom also made a 4-channel with I think something like 65-75 watts per. This would allow me to do the three front channels, with one from each amp left over. (In your situation, the extra channels would take care of your “extra expense” question above.) Adcom also made a low-powered stereo amp in the mid-to-late 80s that you might look into. Don’t be put off by the age – my two GFA-555II amps are still going strong.

Regards,
Wayne


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## BoomieMCT (Dec 11, 2006)

I'd say it depends on what you want to spend. I know everyone says "watts are cheap now" but you are still looking at several hundred dollars for each amp, a few hundred bucks for the active crossovers and a bit more for the extra wiring and wall panels and what-not.

Personally (and this is merely my opinion) I think the speakers should represent 40% - 50% of what you spend on sound. In some cases (like mine where speakers cost in the hundreds of dollars) this means that those hundreds of dollars would be better spent on better speakers, not fancier electronics. In some cases (probably yours where your speakers cost a few thousand) it may well be worth it. Remember that you always want to address the "long pole in the tent". If you have no acoustic treatment, I'll wager you'd get more bang-for-your-buck by doing that. If you have poor speakers (you don't, but _if_) then active x-overs won't help you much. 

Now I've heard (recently) many people say that passive x-overs are no good, they add all kinds of distortion, they rob all your power and they provide no dynamics. Given the liberal use of absolutes in bandied about I'm pretty sure these are gross overstatements of general truths. In fact, the clearest, loudest most dynamic and most emotionally involving system I've heard anywhere ever (HT, live sound, whatever) was a set of B&W 802's properly set up in an acoustically treated room using their stock passive x-overs. 

In summary if cost was not an issue I'd agree active would be the way to go. If cost is an issue you need to figure out if the x-over is the weakest link in the system.


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## Anthony (Oct 5, 2006)

At the very least, I want a 3 channel amp and the electronic crossover to facilitate playing around with different designs and crossover points. Then if I find a point and notch filter that makes the whole speaker sound good, I can design a passive crossover for it.

I don't think I'm ready to do full triamp for the setup. I have my gear at the back and only two conduits running foward (which are almost full). I would need to address that first.

But for prototyping, it may be the way to go.


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## BoomieMCT (Dec 11, 2006)

Anthony said:


> At the very least, I want a 3 channel amp and the electronic crossover to facilitate playing around with different designs and crossover points. Then if I find a point and notch filter that makes the whole speaker sound good, I can design a passive crossover for it.
> 
> I don't think I'm ready to do full triamp for the setup. I have my gear at the back and only two conduits running foward (which are almost full). I would need to address that first.
> 
> But for prototyping, it may be the way to go.


You can borrow my active x-over for testing when the wife isn't using it for her band. It even has a nice portable rack bag to transport in!


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## drf (Oct 22, 2006)

For experimental purposes 20 - 50 watts is more than enough. Have you considered building some chips amps for this purpose? One power supply and 6 chips would be less than $200


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## terry j (Jul 31, 2006)

another thing not mentioned yet is the lack of vol control on the dcx. re the number of filters, I'm afraid that there is not an answer of 'how many', it is a function of processing power, there is a running figure in the screen which tells you where you are at.

Going active?, then go active I reckon. I'm no expert, but (by luck mind ) I'm in Thy's camp as I have oodles of power on all drivers, so hard to imagine I'm running out of headroom. 

I used to use the dcx, now use the deqx. I would _never_ go back, but boy for what you pay the dcx gives a lot of goodies.

Was it you Anthony and Boomie in the other thread with a bit of byplay? If so, I vaguely recall some talk about x-over points etc (and one was a bit more '****' than the other guy ha ha), what flashed into my mind when I read that was the ability of the dcx to 'link the drivers' (or some such description) and then with the two drivers linked you are able to change the crossover frequency in real time. I can imagine _very_ handy for prototyping.

And if it wasn't you two then ignore everything I just said ha ha.


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## Anthony (Oct 5, 2006)

No, that was us. We live about 6 miles apart.

He builds speakers by the seat of his pants. I obsess over every detail. Which is why I've only built 2 in seven years and he's built 10 in only 2 years.


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## groundie (Feb 7, 2008)

folks,
after 2 weeks of fiddling with DCX settings,
i'm back to no EQ at all.
as for crossover frequencies, mine are set 100/3000 or thereabouts
with LR-24. steeper slopes sounded too crispy or trebly; is this
expected?

as for lack of volume control on DCX, i'm using presets for
soft/loud/bass/etc. and do not feel the need for traditional pot type.
for the low price, it also allows me to try out the digital output
of my 10-yr old CD player and sounds better than analog,
more clarity and space.


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## BoomieMCT (Dec 11, 2006)

groundie said:


> folks,
> after 2 weeks of fiddling with DCX settings,
> i'm back to no EQ at all.
> as for crossover frequencies, mine are set 100/3000 or thereabouts
> ...


It could be that the crossover is right near the breakup point of one of the drivers and that the steeper slope is putting a touch more signal at that exact frequency. Or it could just be that the tweeter needs to be padded (turned down) a touch. Do you have the capability to run a frequency response?


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## groundie (Feb 7, 2008)

with DCX, i can set different slopes for woofer and tweeter;
so what works for me is this: 
LR-48 for woofer and LR-24 for tweeter.
that lessens the crispyness or brightness. this is not what i call 'clear'.

yes, i plan to measure the room with REW and see if my ears are
reliable or not to a degree.


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