# Bypass passive 3 way crossover to bi-amp with active crossover



## Maestro (Oct 8, 2009)

Hello All,

I'm looking for advice as to how I should bi-amp my 3 way towers. I have had them bi-amped for a while now using an active crossover/processor (DCX2496). They sound pretty good, but I think they'd sound better if I removed the passive crossover network from inside the speaker cabinet. This is where the problem comes. I have just opened one of my towers. I was expecting to see a bunch of components soldered together, but instead what I have found is a circuit board with everything integrated together on the one board:crying: I don't really want to tri-amp my speakers because it means more processing and amplifier channels (More Money). What I would like to do is keep part of the passive crossover and have either the mid and the tweeter on one channel or the mid with the 2 woofers on one channel. The way the binding posts have been setup from the factory is with the tweeter on its own and the mid and woofers together. Any suggestions or ideas would be greatly appreciated.

Make and Model of Towers:

Monster THX SL200-TWR (don't worry, I didn't pay the retail price for these)


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## Maestro (Oct 8, 2009)

Just so you know, The tweeter has the green wire, the mid has the orange wire, and the woofers both have red wires. Every speaker has a black (common) wire.


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## wgmontgomery (Jun 9, 2011)

You may have more luck in the DIY section; I'll copy this post there. Good luck!!


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## Maestro (Oct 8, 2009)

Thanks


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

Maestro said:


> I don't really want to tri-amp my speakers because it means more processing and amplifier channels (More Money).


As I understand it, there are at least a couple of significant advantages that an active system has to offer. 

One is greater amplifier efficiency. Passive crossovers suck up a lot of power, so with them out of the way you can usually get the same output (SPL) from the speaker with total amplifier power (divided between the drivers) that’s a fraction of what was required for the same speaker with a passive crossover.

The other advantage is potentially improved driver performance, realized when they are free of the encumbrances of all those passive components.

With that in mind, I have to wonder what you can possibly gain by doing a “half-way” conversion like you’re talking about. You might accomplish the improved performance for the driver you choose to direct-amplify, but that’s about it. Hardly worth the effort.

You’d really be better off to bite the bullet and go all the way. The DCX can be set up for a stereo 3-way system, so you’re only out the cost of an additional amp (assuming you already have two stereo models). It shouldn’t be a problem picking up a used low-powered amp like the Adcom GFA 535 (which is probably more than you really need) for under $100 on eBay.

Regards,
Wayne


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## Maestro (Oct 8, 2009)

Hi Wayne,

Thanks for sharing your wisdom, I really appreciate the advice. You are right, it would be a huge amount of work to reconfigure the crossover network just to gain a tiny advantage. I was thinking that I would remove either the highpass or the lowpass passive filter from the mid, depending on which driver I decided to pair with the mid (the woofers or the tweet). That way the mid wouldn't be bandpass, but what a waste of time. 

With my current setup, I have my Front L,C,R all bi-amped, so all of the DCX channels are used. I love having control of the center channel with the DCX, cause I can get crystal clear speech inteligibility with just a little 1.5 dB push in the 2.5 - 3.5K range or suck out a little 200 - 300Hz. Most center channels, to me, sound muddy without tweeking them a little. Maybe it's because I can't afford something that doesn't need to be tweaked:heehee:

I mainly use the system for music, so I think I'd rather hear the towers tri-amped without any passive devices. Either I'll have to buy another DCX or just live without having full control of the center.

Many times, I have heard the difference between passive and active components, and my ears have always chosen active when properly tuned. 

Thanks again Wayne I've got some work to do now.


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

Hey Maestro,

Maybe you can eBay a nice parametric EQ from Ashly, Rane (not the PE15) or Symetrix for a good price for your center channel. Hate to sound like a salesman, but if you “act now” this guy is selling a Klark Teknik DN405 dirt cheap because it’s missing a fuse holder. Maybe you can contact Klark and see if their parts dept. can sell you a replacement. I’ve never used this particular equalizer, but KT is a high-end pro brand, so I’d be surprised – shocked, actually - if it turned out to be a dud. Even if it did, you could easily sell it for more than you paid (provided you get a fuse holder, of course). Search eBay for “klark parametric” to see what the typically asking price is for these things. (BTW, the 410 is a two-channel version of the 405).




> Many times, I have heard the difference between passive and active components, and my ears have always chosen active when properly tuned.


Just curious, can you elaborate on your experiences in this regard? Particularly, have you heard some systems where a passive speaker was converted to active? I know the die-hard DIY speaker guys say going active isn’t as simple as merely chunking the passive crossover for active electronics. I’ve toyed with the idea of going active with my speakers, so anything you can shed on the subject would be appreciated.

BTW,can you edit your first post and hit "Enter" between your pictures, so that this thread doesn't spread from sea to shining sea?

Regards, 
Wayne


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## Maestro (Oct 8, 2009)

Hi Wayne,

That is a good deal on the Klark Technic. I am a big fan of their products. I believe Bosch owns Klark Technic, Midas and Electro Voice. All great companies for the most part. I love Midas mixing consoles. 

Unfortunatelly, for the time being, I don't think my wife would be pleased if I spent $150 on any piece of gear right now, but thank you for thinking of me, that would work quite nice.

As for my experience with passive vs active speakers, I'm sorry if I made it sound like I'm an expert. I have never heard an A/B comparison from passive to active. What I have heard are many different home theaters (because I used to install them). I am also a live sound technician and I have built a small recording studio in our house. So when I said that I have heard many comparisons between passive and active, the comparisons weren't fair, because they were between Home Theater vs Pro Audio. My appologies. But, why is it that these active systems sound so beautiful? I think a part of the reason is the fact that with the click of a mouse a crossover can be tweaked, whereas with a passive system you're kinda stuck with whatever parts "they" put in there or you have to spend hours building a new crossover network that may or may not do what you intended it to.

I have no experience with what I'm doing to my towers. So whatever mods I am doing to these speakers, I have to make sure that it can be reversed. I have almost finished one tower. I have measured the impedance of all the drivers. I know that there can be fluctuations with impedance when the speakers are pushing different frequencies, but I don't know how to measure for this. I'm not too worried about my amps, cause they are just old recievers. I know that the amps are stable at 4 Ohms. I measured each driver on it's own completely disconnected from everything. I got a reading of 8 Ohms for each woofer, so I wired them in parallel to get me close to 4 Ohms. The mid and the tweet read 4 Ohms. So now I should have a 4 Ohm load to each amp channel (I hope). I thought I might have to put some resistors in line, but I got lucky I guess.

I'm probably going to spend days tweaking the crossovers before I do any EQ. I don't want to accidentally blow a driver, so I'll keep the levels down until I know the crossovers are safe.

I'll keep you posted as to how things go, but it will probably take a while cause I've got two toddlers that keep me busy. 

Don't be upset if I don't post for a while. Life is busy.


Thanks again


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