# If bi-amping, do other levels have to raise and increase noise/distortion?



## biscuitg303 (May 13, 2009)

Ok, forgive me if avr's compensate for this already somehow, but l'm getting ready to bi-amp my mains for the 1st time with a denon avr-x2000 OR nad T 748v2. 7 year old midlevel Polks that I still really like.

When bi-amping the mains, do all of the other speakers have to have their levels increased to match the output of the mains, and does this pose a noise/distortion problem to those other speakers since they are boosted to match the higher powered mains?

It seems to me that the gain of the center and surrounds would have to be boosted since they are getting less power than the mains to achieve "equal" sound levels? Will boosting those levels even introduce noise?

Also, does anyone know if I will hear a difference in SQ between those two receivers? 
What concerns me is the the NAD probably sounds better for 2 channel, but the denon offers Audyssey MultEQ and the NAD is whatever generic 'auto calibration' is ... The NAD probably puts out cleaner power, but don't know how good the room correction is? I have not heard either brand. 50/50 HT/Music

Any help with those two questions would be appreciated. TIA


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## ajinfla (May 10, 2009)

Hi Scott,

If you are using the onboard passive biamp feature on your AVRs (I assume both have this capability?), there is no need to adjust levels. You are not going to deliver more power to the speakers (no, power output does not double, maybe a fraction of a db or two at best). So there is no need to mess with your channel gains.
I don't know what you have read or believe, but the only benefit is when you drive the speakers relatively loud. There will be zero difference at lower-mid volumes. Driven to the point where dynamic peaks begin to clip or an amp channel is driven into non-linearity, the spectral distribution of the distortion products will change, because of the different current loading seen by the hi passed tweeter channels (vs the normally single fullrange channel).
Then it is possible that you could hear subtle differences, but it will be very program and listener acuity dependent, unless grossly overdriven. No harm in trying and even if you simply imagine hearing an improvement, that's ok too.

cheers


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## tonyvdb (Sep 5, 2007)

I agree, there is very little if any gain to bi-amping speakers using receivers with the feature. You would likely gain the same is not more improvement by simply making sure you have a large enough gauge speaker wire going to them. At minimum it should be 14awg.


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## biscuitg303 (May 13, 2009)

Wow, really? I always thought that if bi-amped the speaker would have let's say 80w going to the mid/tweet, and an additional 80w going to the woofer (same cabinet) ... 
I need to read up on bi-amping apparently because if that if the benefit is super insignificant I'll just use the other two channels to go to another room vs bi-amping my mains.

any further advice on bi-amping or between those two brands? The NAD is more expensive and doesn't have a usb (which I can use my blu-ray for) Overall SQ is mostly what I'm wanting, but don't know how well NAD does with their calibration system they use. Everyone seems to rave over Audyssey all of the time, so that is why I was even considering the Denon.


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## tonyvdb (Sep 5, 2007)

Realistically the speakers tweeter only requires 5-15watts to reach it's max output all the energy goes into the mids and lows so if you do the math there is really no gain.


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## biscuitg303 (May 13, 2009)

I agree it doesn't take much to drive a midrange and tweeter, but if a person had 80w going to a mid and tweeter, and an additional 80w going to just the woofer, then to me it would make a giant difference vs a tiny one. Not trying to argue, I just don't understand I suppose. I thought I would be basically doubling the power to the speaker by bi-amping.


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## Savjac (Apr 17, 2008)

Doubling the power to the speaker does not mean the speaker will be using it. Think of your car, just going down the road at 55 miles per hour with say 200 hp, now double the power to 400 hp, are you going to notice any difference while still going 55 miles per hour ? Not likely.

The speaker may need some extra power during some demanding bits of music or movies but by using extra channels of a receiver, it is more likely that the actual available power will be somewhat less. Remember, with most AVR's the more channels you use the less power is available per channel. 100 wpc X 2 will usually wind up being 40 wpc X 7 so you really have no gain.

I am not really sure if there is any actual benefit to doing this, I have tried but have not heard anything, however, give it a shot and see what you hear, if you like it then go for it, if there is no difference, no harm is done.


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## ajinfla (May 10, 2009)

This is one of the most widely and wildly misunderstood topics. Try reading my post again guys, its all there.

cheers,


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## nova (Apr 30, 2006)

One thing that you can do by bi-amping this way is change the bass and mid/high characteristics of your speaker relative to each other. Once you bi-amp this way you can change the gain independently. You can boost the bass relative to your mid/highs or vice-versa. It was fun to play around with for a while but in most cases the engineer who designed your speaker had the time, money and resources to design the crossover to take advantage or the drivers strengths and weaknesses better than you could by adjusting the gain. I say give it a try if you want but as the others have said there really is no advantage. Take it from AJ, as I believe he has designed a speaker or two.


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## biscuitg303 (May 13, 2009)

Ok, I suppose I'll just have to try both ways, may not be worth it, thx for responses.

Now, maybe I should ask this somewhere else, but what do you guys feel
about the denon avr-x2000 vs the NAD T 748v2 ? SQ wise. Not interested in bells and whistles, just clean power, I am however also a bit concerned with denon audyssey vs whatever the NAD uses (they don't have a name for it) I hear great things about audyssey and haven't a clue how NAD does in HT applications with their correction system they use.
of note, the denon weighs 20lbs and the NAD weighs 25lbs, may be something to that power wise imo.
I've heard that the NAD is underrated, and will put out great clean sound at all volume levels is why I'm throwing that one into the mix. Not interested in anything sony or onkyo whatsoever.


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## Savjac (Apr 17, 2008)

ajinfla said:


> This is one of the most widely and wildly misunderstood topics. Try reading my post again guys, its all there. cheers,


Sure AJ we know, but if we start agreeing with you on a regular basis, that could be bad for the size of your old hats.


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## ajinfla (May 10, 2009)

biscuitg303 said:


> Ok, I suppose I'll just have to try both ways, may not be worth it, thx for responses.
> Now, maybe I should ask this somewhere else, but what do you guys feel
> about the denon avr-x2000 vs the NAD T 748v2 ? SQ wise.


As you note, no harm in trying it, other than another pair of wires. As I note, whether there is a real or imagined improvement should matter scant. It's your ears/brain you need to please.
Linear SS amps, especially in AVRs, do not possess a "sound", unless driven into non-linear behavior. As such, in say, "Direct" mode (all processing off), the only real "sound" difference, will manifest only if they are being stressed.
Impossible to say unless there is data for both and your speakers. Let's just say the probability is rather low.
However, in routine, casual listening, imagination can create differences in the mind as real as in the soundfield. You'll read that daily on every audio forum.



biscuitg303 said:


> Not interested in bells and whistles, just clean power, I am however also a bit concerned with denon audyssey vs whatever the NAD uses (they don't have a name for it) I hear great things about audyssey and haven't a clue how NAD does in HT applications with their correction system they use.
> of note, the denon weighs 20lbs and the NAD weighs 25lbs, may be something to that power wise imo.
> I've heard that the NAD is underrated, and will put out great clean sound at all volume levels is why I'm throwing that one into the mix.


The NADs lack of Room EQ should tilt the odd in favor of the Denon in terms of better perceived sound, in your room.
However, all else equal, it is possible the NAD might be capable of putting out a bit more power, into more demanding loads, for the reason you mentioned, a (possible) beefier power supply. But once again, without data for both and your speakers, that is largely speculation.

cheers,


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## ajinfla (May 10, 2009)

Savjac said:


> Sure AJ we know, but if we start agreeing with you on a regular basis, that could be bad for the size of your old hats.


..and helmets. Don't forget helmets.


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## Savjac (Apr 17, 2008)

Good Point AJ, Helmets too, cannot forget those. :clap:


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