# Bi-Amping 3 channels ?



## TomFord (Jul 15, 2014)

Good evening gentlemen,

Looming for an amp to provide an additional 30-50 watts to my left, center, and right channels. Want to utilize the HF & LF terminals on each of the speakers. Heard some talk of it making zero difference, but why would the company design them like that? For looks? Has to sound better or operate more efficiently for a company to add thextra additional cost to manufacturing

Noticed an Emotiva amp I've never seen called the stereo flex that delivers 
100 x 2. Is the only way to bi-amp them a 5 channel? 

Appreciate any assistance or recommendations


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## |Tch0rT| (May 2, 2013)

TomFord said:


> Looming for an amp to provide an additional 30-50 watts to my left, center, and right channels. Want to utilize the HF & LF terminals on each of the speakers. Heard some talk of it making zero difference, but why would the company design them like that? For looks? Has to sound better or operate more efficiently for a company to add thextra additional cost to manufacturing


Adding an additional 30-50 watts isn't going to make any audible difference unless you're at 30-50 watts. Double the watts adds 3dB of volume. Passive Bi-amping and Bi-wiring does nothing except make cable manufacturers more money. Yeah sure it adds to the cost of manufacturing but probably not by much and they probably pass it along to the consumer. Speaker companies make speakers that way so they don't alienate people who believe in passive bi-amping and bi-wiring. It makes sense for a manufacturer to add the bi-wiring because it entices the people who believe in it and the people who know bi-wiring does nothing just ignore the "feature". This link explains why passive bi-amping and bi-wiring does nothing:
http://www.chuckhawks.com/bi-wire_bi-amp.htm

Active bi-amping is another story altogether however...


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## GCG (Aug 22, 2013)

First the cost is minimal. Isolating the woofer crossover in most cases involves eliminating one circuit trace. Then add in an extra set of terminals or solder points on the crossover board, an extra set of binding posts, jumpers and some wire.

Got to agree on the Active vs. Passive bi-amping. You may hear some difference with passive bi-amping but to hear it both you and your system would have to be especially capable.


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## TomFord (Jul 15, 2014)

Thanks. I'm now looking at the Emotiva 5 & 7 channel amps. By active bi-amping you mean where I'd be able to adjust certain aspects opposed to strictly sending power correct? 
I've never used a power amplifier (almost 3 months with Home Theater experience) with the quality of a Emotiva. Understand the circuitry well, it's just been a decade since I became a certified electronic technician due to having only 2 classes Sr year & Vo-Tech being free so I thought it'd be very beneficial with the cpu boom going on at the time. 
We mainly learned of the internal parts you see on a board. The designs Emotiva uses (I'm sure many others at the price range as well, but don't see them showing internals) are amazing to be at the prices they offer. Particularly the UPA 500 & 700. Do these allow the adjustments to be active? Was reading on their site & it wasn't very clear on what you're able to adjust. Or would I need a separate EQ for it to be active bi-amping? 

Trying to have all of speakers at their peak performance/efficiency (KEF rep said they operate best at 10-30 watts over the recommended 150 speaking in terms of least likely to any damage) before the KEF R50 ships & I install the 2 ceiling speakers unsure of the models, when the Dolby Atmos firmware update comes on 9/28. 

Important question I haven't asked. My Onkyo TX-NR838 is 7.2 channel yet is able to play the zone 2 from the same source as other 7 channels unlike the lower models. I will have to get rid of my front height speakers which is what the KEF R50's will run on, do i use the surround back for the 2 ceiling speakers? Know I have to use the heights for one, yet unsure of the others. 
Wish I was able to add an additional AVR to this one

As always, truly appreciate any assistance or advice fellas


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## NBPk402 (Feb 21, 2012)

An example of Active Bi-Amping would be this...

1: Disconnect the current crossovers
2: Get a MiniDSP for a crossover (a 2x4 can do 2 channels Bi-Amped) There are other options but the MiniDSPs are inexpensive and do the job
3: Hook up to 2 channels of amplification for each speaker preferably with individual volume control
4: Hook up your wires to the amps, and then configure the crossovers
5: Tune your setup


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## GCG (Aug 22, 2013)

In active bi-amping the crossover is "active" (read powered) and comes before the power stage. The passive crossovers in the speakers are removed or didn't exist in the first place. By isolating the frequency spectrum for each speaker prior to power amplification the amps are only fed those frequencies. 

Before I dropped serious coin I'd take the time to get the most of the system as is. Separate PAs aren't a bad idea especially for the fronts, but I like baby steps not giant leaps. You'll appreciate the journey more IMO.


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## GCG (Aug 22, 2013)

Boy, walk away for a minute and ... ninja'd

MiniDSP is an affordable option I had over looked. But setting up crossovers isn't exactly plug-n-play. You'll need to do full range sweeps on individual drivers to get the data you'll need to find optimal cross point(s). Can you recognize cone break-up on a sweep trace? Then which profile to chose; Butterworth, Linkwitz-Riley, Bessel of what order? What about time alignment? Phase issues? Baffle stop loss management?

Not trying to dissuade just full disclosure.


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## |Tch0rT| (May 2, 2013)

Going active isn't for everyone. It has extra setup steps and if you don't get them right you might fry a tweeter if you do the DIY building of your own or converting an existing pair. There aren't many consumer active speaker setups outside studio monitors.

The benefits are the amps are more efficient since they only have to amplify a narrower bandwidth along with less amp power lost to heat dissipation from the passive Xover, the amps have direct control of the driver (better damping factor), and the woofers no longer influence the tweeters (in a passive setup if the woofer starts to distort it forces the tweeter to distort even if it normally wouldn't at that level). There's also the convenience of being able to tweak drivers in real time.

To me active speakers feel a bit more dynamic and more alive than passive.

Once the warranty is up on my MartinLogan EM ESL's I plan to convert them to active.


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## TomFord (Jul 15, 2014)

Trying to address multiple posts. Also, this is something I would need to do a lot of research on before attempting & wouldn't do so on one of the KEF's intially.
In order for let's use one speaker in this example the KEF Q700. It has 2 6.5 ABR woofers, 1 6.5 LF woofer, 1 6.5 Uni-Q with a 1 inch tweeter. Currently it's internal crossover is at 2.5kHZ. I would need to determine the ranges on the tweeter, Uni-Q, LF, & ABR woofers. Here's where I'm a bit confused, remove the crossover inside the tower & wire them so that each (in this case the 2 ABR acting as one) speaker is receiving it's own amplification? Having the watts being supplied only to the frequency range of each speaker? For example on the LF woofer (rough estimate) sending only 20 Hz - 200 Hz. Am I on the right path?

Don't believe this would be the case yet you don't mean me doing the math & soldering the capacitor & coil combination that creates the proper crossover for each correct? 

I'm going to look into & learn more of the DSP & how they operate. If you know any source material that'd be beneficial I'd appreciate the recommendation as I'm clearly confused never having heard of this. See what I can learn


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## GCG (Aug 22, 2013)

If you'll note the Q700's are a 2.5 way design which means they are using one of the drivers for baffle stop compensation. 2.5 may be descriptive of the function but in application there are three distinct seperate driver freq bands being developed. The 2.5kHz xover listed isolates the upper freqs for their "Uni-Q" driver while everything lower going to to the rest. If it truly is a 2.5 one of those is crossed lower to accommodate the baffle stop loss that comes from having a narrow face on the front of the speaker cabinet. It's physics and you can't avoid it. The big red flag for me would be that they don't give you any info on the crossover except that is low order. That second cross has to be lower in freq to get back the low end lost to the 8.3" wide baffle without bloating the mid-low end above the baffle stop. In any event if you go active their xover has to go and you'll need 3 amplifier stages per speaker not just 2. 

Good luck. Don't throw the KEF xovers. I'm betting you'll put them back in.


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## |Tch0rT| (May 2, 2013)

TomFord said:


> Don't believe this would be the case yet you don't mean me doing the math & soldering the capacitor & coil combination that creates the proper crossover for each correct?


You wouldn't be soldering caps and coils. All the crossover functions would be done electronically. You'd need something like a Behringer DCX2496 for those KEF speakers not to mention it would be helpful to have a measurement mic and learn REW. This is pretty advanced stuff though and gets expensive so if you're not comfortable don't do it.

Here's a diagram of an active setup:


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## NBPk402 (Feb 21, 2012)

|Tch0rT| said:


> You wouldn't be soldering caps and coils. All the crossover functions would be done electronically. You'd need something like a Behringer DCX2496 for those KEF speakers not to mention it would be helpful to have a measurement mic and learn REW. This is pretty advanced stuff though and gets expensive so if you're not comfortable don't do it.
> 
> Here's a diagram of an active setup:


Link doesn't work...


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## GCG (Aug 22, 2013)

What I'd like to know is why you would throw away a 5 year warranty on something when it's clear you are uninitiated in the skills required for the level of success that I'm fairly certain you're after? Not to say you couldn't acquire those skills, but there are other things that could be done to improve system performance without the financial risk and at a lower cost. Why not simply start with moving to separate amps on all channels. That alone would reap gains by eliminating the headroom limits that a multi-channel AVR is subject to. Then as funds and more importantly knowledge and skill allow, move on to more ambitious endeavors.


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## ajinfla (May 10, 2009)

|Tch0rT| said:


> Passive Bi-amping and Bi-wiring does nothing except make cable manufacturers more money.


Not true. Buywiring is indeed nonsense, but passive bi-amping is not. I've explained it here before, but I hate typing (and thus retyping), so I'll just provide a link.

cheers


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## |Tch0rT| (May 2, 2013)

ellisr63 said:


> Link doesn't work...


Weird, uploaded it to my dropbox.












ajinfla said:


> Not true. Buywiring is indeed nonsense, but passive bi-amping is not. I've explained it here before, but I hate typing (and thus retyping), so I'll just provide a link.
> 
> cheers


Ah I guess I didn't read enough into to it and assumed it was another name for buywiring (love it lol). So basically the benefit to passive bi-amping is the tweeter is no longer a slave to the woofer when the woofer distorts which would only really be a benefit at high volumes but forfeits the other benefits of active bi-amping?


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## GCG (Aug 22, 2013)

|Tch0rT| said:


> ...
> the tweeter is no longer a slave to the woofer when the woofer distorts which would only really be a benefit at high volumes but forfeits the other benefits of active bi-amping?
> ...


Yeah but throw in four external amps to bi-amp the fronts and now the OP is benefiting from five separate power supplies and passive bi-amping. No hacking new warrantied speakers, no steep learning curve and if all is not up to the high hopes, his options aren't any more limited than they are now. If he was willing to drop the coin to do the full active thing this should be a drop kick no brainer. He loses nothing, the system improvement potential is there, and he can still go active down the road using the same amps.


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## willis7469 (Jan 31, 2014)

Someone posted earlier about focusing on things like room treatments and such. I think that's good advice. As much as I'd love to see Tom go crazy, I think he's only 3 months into the hobby,(?) and he's finding solutions for problems that he doesn't have yet. I feel like he should just spend some serious QT with the system, really paying attention to detail and Then he'll know why he wants to change what. Kind of in the same way we recommend for ppl to change one thing and see what happens, instead of a few things at once, and not know what did what. I'd recommend starting with placement, and room treatment. Sorry if I missed the idea...


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## GCG (Aug 22, 2013)

Best move for sure. I just wanted to steer the OP away from cutting up new speakers. I'm a fan of baby steps but when someone gets the fever, sometimes all you can do help them put on the brakes.


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## willis7469 (Jan 31, 2014)

Lol. It's usually me who needs the brakes applied! I think you gave good advice.


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## |Tch0rT| (May 2, 2013)

Yeah sorry I didn't mean to steer the OP to go active. A good example of just because you can doesn't necessarily mean you should. Passive and Active Bi-amping would be more along the lines of advanced/final stages of tweaking once you'd done cheaper and more practical options if you so fancy it.

Definitely go with the free option of trying to find a good placement of the speakers first. Then maybe venture to get a measurement mic and learn REW (it's not as hard as it initially seems) so you can see areas in where you need improvement and see the impact of the changes you make like room treatments, multiple subs, EQ, etc.


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## GCG (Aug 22, 2013)

Years ago when I began reading on the subject of placement, that alone made a vast improvement that my wife and myself found astounding at the time. Just getting the tweeters to the correct height can make a night and day difference. Made these stands to do just that.










Now if we don't get the same SQ (we recently moved to a new home) my wife is quick to let me know I have work to do.


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## willis7469 (Jan 31, 2014)

That's great! My wife would say the improvement would come from me removing them altogether!


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## ajinfla (May 10, 2009)

|Tch0rT| said:


> So basically the benefit to passive bi-amping is the tweeter is no longer a slave to the woofer when the woofer distorts which would only really be a benefit at high volumes but forfeits the other benefits of active bi-amping?


The benefit is solely at high enough levels, when (not if) the amps (vs "amp") are driven to non-linear behavior, the woofer amp clips first, but the clipping spectra (which becomes quite audible) is now low passed by the woofer filter and the tweeter amp is not clipping and passes a clean signal to the tweeter.
This is vs a single clipped amp channel where you get the entire clipping spectra emitted from the speaker to your ear.
Passsive bi-amping _can_ be (rather than *is*) beneficial.
Buywiring OTOH, is (electrically) slightly different than single wire, but as far as _audibility_ goes, I say, show me the money. Good luck with that.

cheers,


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## TomFord (Jul 15, 2014)

Working on a crossover now to try on one of the additional Pioneer towers I have before I do the KEF. Simply to try it on low costing equipment first & see the improvements I can get with this. Also to just solder a few components since it's been a few years.
Would you do 3 crossovers in the Q700, & at what frequencies? Also, why do you imagine I'll put the KEF crossover back in?


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## |Tch0rT| (May 2, 2013)

ajinfla said:


> The benefit is solely at high enough levels, when (not if) the amps (vs "amp") are driven to non-linear behavior, the woofer amp clips first, but the clipping spectra (which becomes quite audible) is now low passed by the woofer filter and the tweeter amp is not clipping and passes a clean signal to the tweeter.
> This is vs a single clipped amp channel where you get the entire clipping spectra emitted from the speaker to your ear.
> Passsive bi-amping _can_ be (rather than *is*) beneficial.
> Buywiring OTOH, is (electrically) slightly different than single wire, but as far as _audibility_ goes, I say, show me the money. Good luck with that.
> ...



Thank AJ! I remember your nick ever since I stumbled across online audio forums years ago and I've probably learned a lot from your posts over the years. :bigsmile:


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## GCG (Aug 22, 2013)

TomFord said:


> Working on a crossover now to try on one of the additional Pioneer towers I have before I do the KEF. Simply to try it on low costing equipment first & see the improvements I can get with this. Also to just solder a few components since it's been a few years.
> Would you do 3 crossovers in the Q700, & at what frequencies? Also, why do you imagine I'll put the KEF crossover back in?


Your post makes me afraid you are out of your depth. Without a freq response curve on each driver there is no way to accurately determine a xover freq. Do you have the tools to do this? Also, if you are trying to design a xover that makes me think you plan to go the active route. If you were going passive you'd be using the KEF's as is and you wouldn't be soldering anything. If you're going active you still don't need a soldering iron. You need an ACTIVE crossover. Here's an example: (This does not imply this is a recommendation)

http://www.parts-express.com/behringer-cx3400-super-x-pro-crossover-3-way-4-way--248-668

... or better a MiniDSP.

You would need one for each speaker and you'd need to resolve the transition from the unbalanced outputs of the AVR to the balanced inputs of the xover. The Behringer unit is a fixed 4th order Linkwitz Riley and while it may work for the upper end and mid-bass, being fixed at a 24db per octive roll off, it may not be a fit for the roll off due to the baffle stop comp on the very low end. That cross would be strictly dependent on the roll off of the mid-bass which is a function of the width of the baffle. You would then need one amp for each driver. Crossover design isn't something that you just do like hooking up components. There's a lot more to it. Please take a pause and rethink.

As for recommending to keep the KEF xovers. At the skill level you are showing me I would expect that the performance of the finished product would be abysmal and KEF xovers would go back in ... after voiding your warranty. I'm sorry to be so blunt but you haven't taken repeated hints.

I know you are doing prelim work on off line units (the Pioneers) but you need to do a lot more reading before even doing that.


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## willis7469 (Jan 31, 2014)

TomFord said:


> Working on a crossover now to try on one of the additional Pioneer towers I have before I do the KEF. Simply to try it on low costing equipment first & see the improvements I can get with this.


 Tom, how do you intend to "see the improvements"? Sorry I don't recall if you're using rew. Certainly you don't need to justify your experiment to me, but it seems like the equivalent of driving a car once, and tearing it down and rebuilding it with performance parts of your own creation with information gathered on the Internet, with not much experience, and not much driving data to reference. I don't remember you saying anything was lacking. What's the motivation? I'll buzz off if you lik, but I'm genuinely curious.


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