The Difference Between Bi-amping and Bi-wiring

[RichB]

Passive bi-amping is much closer to active than bi-wiring.
There is an improvement bi-aming the Salon2's with the Parasound A21's.

I did some SBT's as well. It is easy to hear.
Many have read the theory and tried an experiment and now and forever have made up their minds.

If you like it, don't let others talk you out of it. I don't

- Rich

 

[Irvrobinson]

Passive bi-amping is much closer to active than bi-wiring.
There is an improvement bi-aming the Salon2's with the Parasound A21's.

I did some SBT's as well. It is easy to hear.
Many have read the theory and tried an experiment and now and forever have made up their minds.

If you like it, don't let others talk you out of it. I don't

- Rich

I tried passive bi-amping with the Salon2s and couldn't discern a difference, like I could with original Legacy Focus. So I let three channels in a AT3005 sit idle. Nonetheless, passive bi-amping and even bi-wiring almost always does no harm. Yeah, in most cases both strategies don't improve anything, but so what? If you can discern a difference I say go for it.

I've had several people ask me about using extra receiver or amp channels, and I always say go for it if you want to, that it'll do no harm. I also tell them it'll probably do no good, but being a technical purist and showing disdain for something non-technical enthusiasts think is cool makes you unpopular and aloof.

People just want to have fun in this hobby, and not everyone is trying to make a drum kit sound live in their living rooms. Most more normal enthusiasts I meet think I'm the weird one.

 

[PENG]

I tried passive bi-amping with the Salon2s and couldn't discern a difference, like I could with original Legacy Focus. So I let three channels in AT3005 sit idle. Nonetheless, passive bi-amping and even bi-wiring almost always does no harm. Yeah, in most cases both strategies don't improve anything, but so what? If you can discern a difference I say go for it.

I've had several people ask me about using extra receiver or amp channels, and I always say go for it if you want to, that it'll do no harm. I also tell them it'll probably do no good, but being a technical purist and showing disdain for something non-technical enthusiasts think is cool makes you unpopular and aloof.

People just want to have fun in this hobby, and not everyone is trying to make a drum kit sound live in their living rooms. Most more normal enthusiasts I meet think I'm the weird one.

I agree with you 100%. If one thinks he/she could discern the difference whether that is real or not, it is a good thing. I know there is no "audibly" discernible difference but I would do it just to feel good. Same reason why I really don't need some of my amplifiers and DACs but I have them, and will keep them all. I think ADTG is in the same boat on this.

 

[AcuDefTechGuy]

I agree with you 100%. If one thinks he/she could discern the difference whether that is real or not, it is a good thing. I know there is no "audibly" discernible difference but I would do it just to feel good. Same reason why I really don't need some of my amplifiers and DACs but I have them, and will keep them all. I think ADTG is in the same boat on this.

I do love my 4 ATI amps.

I got AT2000 series, AT3000 series, AT6012 series. Sometimes I'd be trying to come up with excuses to get the AT1800 & AT1200 series.

I don't do any passive bi-amp, though. It goes against my audio religion.

 

[RichB]

I tried passive bi-amping with the Salon2s and couldn't discern a difference, like I could with original Legacy Focus. So I let three channels in AT3005 sit idle. Nonetheless, passive bi-amping and even bi-wiring almost always does no harm. Yeah, in most cases both strategies don't improve anything, but so what? If you can discern a difference I say go for it.

These posts are attributed to "From the Top" (which is likely Voecks) from AVS:

http://www.avsforum.com/forum/89-speakers/710918-revel-owners-thread-267.html#post40821682

From Revel: not a fan of bi-wiring:

...it turns out that the difference most people hear bi-wiring, if there is any audible difference, is due to mis-termination of the speaker crossover. As you know, a filter network (crossover) must be terminated on its input and output with a known load. The input side then is sensitive to the simple loop resistance of the speaker cable. (We assume a solid state amplifier, but many customers are very pleased with the results using tube amps—including with the Salon2.) Solid-state amps (assuming they do not use output transformers) present a very low-impedance input to the speaker; almost a “short.”...People often hear an effect from bi-wiring due to increasing the loop resistance of the cable to each section, and mis-terminating the filter. Several dB of peaks and dips around the crossover point can result. But when people have changed to bi-wiring, they unfortunately assume it is an improvement, even when it is actually a degradation. The worst examples are bi-wire cables with thinner wire for the tweeter than the woofer. They should of course be the same gauge, as it is not a case of “fitting little high frequencies into smaller wire,” which is the quality of the logic of anyone making such cables.

I've had several people ask me about using extra receiver or amp channels, and I always say go for it if you want to, that it'll do no harm. I also tell them it'll probably do no good, but being a technical purist and showing disdain for something non-technical enthusiasts think is cool makes you unpopular and aloof.

http://www.avsforum.com/forum/89-speakers/710918-revel-owners-thread-267.html#post40821322

From Revel: There can be positive resutls from bi-amping:

I too, have heard such effects from passive bi-amping. If the speaker is competently designed, you would never want to insert active crossovers, except for a rare case in which the transfer function required to properly “cross-over” the speaker is published and properly implemented. Otherwise, passive bi-amping can offer sonic improvements. One reason is likely that the impedance outside the pass-band rises dramatically—thus resulting in the amp not being significantly utilized outside the intended frequency range. So for example, an amp dedicated to the high-frequency section of a speaker (whether that is a tweeter alone, or perhaps a tweeter and midrange), will not have significant current draw at low frequencies, resulting in lower distortion.

GSR on our quick listening session comparing the A21 single channel, A21 Bi-amped, and JC-1:

http://www.avsforum.com/forum/89-speakers/710918-revel-owners-thread-267.html#post41066442

From GSR:

RichB and I conducted a somewhat non-scientific comparison on Tuesday. I lugged one of my Parasound JC-1's over to his place. Before hooking up the JC-1, he wanted to demonstrate the difference between using a single Parasound A21 channel on each of his Salon 2's versus bi-amping then with 2 A21 channels on each. Once we found some quality recordings that I was reasonably familiar with, the difference was fairly obvious in favor of bi-amping.

Next, we took the right channel out of the equation since we only had a single JC-1 to compare with. We confirmed that the single amp channel versus bi-amping difference was still noticeable.

We then hooked up my JC-1 in place of his A21 and we both felt that the JC-1 was a reasonably significant improvement over the A21 in either configuration.

Since I was just over there during my lunch break (albeit a somewhat long lunch break), we didn't have time to level match, but the improvement the JC-1 brought to the table was significant enough that I don't believe we would have come to a different conclusion if we had been able to take the time to do so.

We also switched the JC-1 between high bias and low bias mode without any discernible difference in sound quality, presumably because we weren't playing music loud enough to leave class A in either case (10 watts in low bias versus 25 in high bias).

I suspect that the result could easily be different with speakers that are less difficult to drive than Salon 2's, but at least in this case there's definitely a difference.

The next step is for RichB to decide if he sticks with his A21's or upgrades to something else and if I stick with my A51 to drive the center, sides, and rears (I've got a Voice 2 and a total of 3 pairs of Salon 2's in my system). I believe the most likely candidate amps are JC-1's or ATI Signature series for RichB and ATI Signature series for me.

My prelimary conclusions are:

• The Salon2's are somewhat difficult to drive and examination of impedance curves is not telling the whole story.
• Audible improvements can be heard with the A21 bi-amped
• Bi-amp improvements can be heard at low volume levels (it is not a power issue)
• Bi-amp improvements are likely based on amplifier linearity when driving a complex speaker load with low impedance dips (Salon2's can 3.4 ohms)
• JC-1s also provided this benefit single amped.
• Bi-Amping Salon2's leaves open to option of PEQ on the bass only (for purists)

It has been a while since I had the AT3005 in my sytem, but I suspect that ATI amps are better able drive the Salons so there may be no significant benefit.

The Salon2 impedance is a bit more demanding that the specs. The attached measurements come form the source

People just want to have fun in this hobby, and not everyone is trying to make a drum kit sound live in their living rooms. Most more normal enthusiasts I meet think I'm the weird one.

Awesome. Audioholics left normal behind a while back

- Rich

 

[Irvrobinson]

By my experience the Salon2s are very easy to drive, though they do have rather low efficiency (~86db/2.83v/m), so in a big room a lot of power is called for.

The original Legacy Focus, now that was a PITA for an amp. Three twelve inch woofers (wired in parallel?), with enough total back EMF (apparently) to start a tractor, low frequency low-pass and high-pass filters, like TLS Guy despises so much, a pair of kevlar midrange drivers that probably needed special crossover help, a tweeter that reached lower than normal to allow the midrange drivers to roll off early, and then a leaf super tweeter, probably because the tweeter that reached so low wasn't so good up top. The minimum impedance in the bass on my pair was measured at below 2 ohms. Ostensibly very efficient, but even with Levinson 334 amps they sounded better bi-amped. The mids and highs seemed markedly cleaner. I should have swapped out the Foci long before I did, but back in the 1990s most speakers sucked, IMHO. Even if they didn't, they usually had a very audible flaw that drove me nuts. Or I couldn't afford the ones that really sounded good.

 

[AcuDefTechGuy]

We all know the big woofers require the most power - the midrange and tweeters require a lot less.

When the sound quality is claimed by some people to be improved with passive bi-amp, what is being improved? The tweeters and midrange that require much less power?

 

[j_garcia]

The driver only needs so much power to achieve a given SPL clearly, and the tweeter and mids need far less, so where the benefit might be is with the woofer. STILL, as I've always said, if you simply have enough power for the speaker as a whole to achieve the output level you want clearly, there is no need for biamping beyond that; you are not adding anything.

 

[Irvrobinson]

We all know the big woofers require the most power - the midrange and tweeters require a lot less.

When the sound quality is claimed by some people to be improved with passive bi-amp, what is being improved? The tweeters and midrange that require much less power?

When a speaker is Passively bi-amped, how much power can Actually be added or provided?

Big woofers don't require more power. Big bass requires more loudness in the bass frequencies, and the greater loudness requires more power. 90db from a tweeter takes just as much power as 90db from a woofer, but 90db from a woofer is less interesting, right?

In my one case, with the Legacy Focus, the improvement in sound quality had nothing to do with power. I found that the upper mids and highs caused less listening fatigue. It was more pleasant to listen to. Perhaps I was just imagining things, but I doubt it. Since I was vertically bi-amping it wasn't a bad amp either. Nor did I think the difference was subtle.

I'm not sure I understand the question about how power can be added. With horizontal bi-amping it could be hundreds of watts per channel for the woofers. If the amps have level controls, you can even crudely mimic active bi-amping to a limited degree.

Nonetheless, just to reiterate my position on passive bi-amping, I don't think it improves the system 99+ percent of the time.

 

[Steve81]

When the sound quality is claimed by some people to be improved with passive bi-amp, what is being improved?

It's not so much about the additional power, but goes back to this quote pointed out by Rich:

Otherwise, passive bi-amping can offer sonic improvements. One reason is likely that the impedance outside the pass-band rises dramatically—thus resulting in the amp not being significantly utilized outside the intended frequency range. So for example, an amp dedicated to the high-frequency section of a speaker (whether that is a tweeter alone, or perhaps a tweeter and midrange), will not have significant current draw at low frequencies, resulting in lower distortion.

Remember, the woofer and mid/tweeter circuits are divorced from one another. As such, if the amp driving the woofers is starting to run out of steam, the resulting distortion will remain on the woofer circuit, as opposed to being fed to the mid/tweeter circuit. This is beneficial, as the distortion will be tamped down both by the woofer's low pass filter as well as the natural rolloff of the woofer.

 

[RichB]

Big woofers don't require more power. Big bass requires more loudness in the bass frequencies, and the greater loudness requires more power. 90db from a tweeter takes just as much power as 90db from a woofer, but 90db from a woofer is less interesting, right?

In my one case, with the Legacy Focus, the improvement in sound quality had nothing to do with power. I found that the upper mids and highs caused less listening fatigue. It was more pleasant to listen to. Perhaps I was just imagining things, but I doubt it. Since I was vertically bi-amping it wasn't a bad amp either. Nor did I think the difference was subtle.

I'm not sure I understand the question about how power can be added. With horizontal bi-amping it could be hundreds of watts per channel for the woofers. If the amps have level controls, you can even crudely mimic active bi-amping to a limited degree.

Nonetheless, just to reiterate my position on passive bi-amping, I don't think it improves the system 99+ percent of the time.

I don't know how to anticipate a benefit and I agree that this is not a power issue. It seems to be a distortion issue (or failure to remain linear).

With the Salon2's, the bass crossover is no longer connected to the upper crossovers and this seems to have an impact on the performance of the A21. It seems that an amplifier that can drive more difficult loads may not experience the same interaction or benefit. I thought the A21 was up to the challenge but I now have reason to doubt that.

Pejorative terms like "Fools Bi-amping" and other boorish forum behavior seems to dissuade many from trying. For those interested, I recommend the following:

• Use a Pure Direct mode (don't use DSPs to duplicate the channel)
• Split your signal with a Y connector to 2 channels of your current amp
• Drive only one speaker (Harman does it, it works at home too )
• Use stackable banana-plugs to make switching easy (and less dangerous)

Let someone else both be the listener and the gear switcher.
Of all the experiments you can try, this one is very cheap. It only costs if you find a benefit and have to obtain additional channels of amplification.

- Rich

 

[AcuDefTechGuy]

if the amp driving the woofers is starting to run out of steam

Isn't this the salient point of all this passive bi-amp?

If the amp doesn't run out of steam in the first place, there wouldn't be any distortion issues (clipping).

But I guess the point is also: just in case it runs out of steam.

And also: if it makes you happy, it can't be that bad.

 

[PENG]

It's not so much about the additional power, but goes back to this quote pointed out by Rich:



Remember, the woofer and mid/tweeter circuits are divorced from one another. As such, if the amp driving the woofers is starting to run out of steam, the resulting distortion will remain on the woofer circuit, as opposed to being fed to the mid/tweeter circuit. This is beneficial, as the distortion will be tamped down both by the woofer's low pass filter as well as the natural rolloff of the woofer.

I also agree with you but that's not what rich seem to be saying in your quote though. He clearly stated that he got the benefits at low volume too and he also said it was not due to more power as much. So I take it that he did not attribute to the benefits to the HF amp not running out of power because it does not have to deliver (or drawn by the tweeter) the low frequency currents.

If he is talking about distortion due to the influence of the low frequency current in the same wires then we had this debate before many times on different threads, the theoretical benefits of passive biamp over biwire isn't much if more power is not the issue. In fact one may argue that a single 300W ATI biwire could provide more theoretical benefits than a pair of 100W ATI amp biamped. IMO all those benefits are theoretical and are only audible to some people, Rich is one of those for sure. Again, I am in the camp that I believe people should do it even if it is just theoretical, as long as people find it affordable. I know I am not the only one, so there really are 3 camps at the minimum and the debate will never die.

 

[PENG]

I don't know how to anticipate a benefit and I agree that this is not a power issue. It seems to be a distortion issue (or failure to remain linear).

With the Salon2's, the bass crossover is no longer connected to the upper crossovers and this seems to have an impact on the performance of the A21. It seems that an amplifier that can drive more difficult loads may not experience the same interaction or benefit. I thought the A21 was up to the challenge but I now have reason to doubt that.

Pejorative terms like "Fools Bi-amping" and other boorish forum behavior seems to dissuade many from trying. For those interested, I recommend the following:

• Use a Pure Direct mode (don't use DSPs to duplicate the channel)
• Split your signal with a Y connector to 2 channels of your current amp
• Drive only one speaker (Harman does it, it works at home too )
• Use stackable banana-plugs to make switching easy (and less dangerous)

Let someone else both be the listener and the gear switcher.
Of all the experiments you can try, this one is very cheap. It only costs if you find a benefit and have to obtain additional channels of amplification.

- Rich

Rich, I like your innovative thinking but if you believe this is not a power issue as you stated more than once, then whether it is an A21 or ATI3000 series amp should make no difference. No matter how difficult a load the Salon2 is, if the amp is only asked to run at a few volts or 20 volts, there shouldn't be any audible distortions. 20V into 2 ohms is only 10 amp!! I think the difference you are hearing is due to the fact that in passive biamping, the tweeter circuit has very little low frequency currents and the theoretical effects (or benefits if you prefer) of that is well documented. What is debatable is only if such effects should be audible to humans or not.

 

[AcuDefTechGuy]

The salient point is that Rich is happy. That is what matters at the end of the day.

I have Kimber Kable speaker wires. I like it.

 

[RichB]

The salient point is that Rich is happy. That is what matters at the end of the day.

I have Kimber Kable speaker wires. I like it.

Bi-amping does have some manufacturer support. There is also reasonable science in that amps react differently to load changes. All amps distort and most measurements are not complex waveforms driving loads. Reducing the load on an amp reduces distortion even when the amp is not "clipping".
The degree of distortion is audible (driving a speaker) is not fully understood.
Passive crossovers networks can be very good but are not necessarily linear and may interact when connected.

Passive Bi-amping may be beneficial and worthwile but it depends on your speakers, amp, and perception. By that, I mean if a person finds no benefit, that is a completely valid conclusion as is finding a benefit.

The salient points are:

• The claim that passive bi-amping is a waste and of no possible benefit is FALSE.
• Bi-amping is simple to try at home and hear for one-self

I don't know how to be clearer that that

I use Monoprice 12x4 cables. I suppose it is possible the Kimbre cables improve sound. I am not going to spend hundreds of dollars to find out.

Harmon (Veocks) is clearly NOT recommending bi-wiring.

- Rich

 

[AcuDefTechGuy]

The claim that passive bi-amping is a waste and of no possible benefit is FALSE

You mean it should be rephrased as "Passive bi-amp may or may not benefit some people"?

I love Kimber Kable only because they look cool. That's it.

 

[RichB]

You mean it should be rephrased as "Passive bi-amp may or may not have benefits"?

It may not benefit 50% of people, but it may benefit the other 50% of people.

I love Kimber Kable only because they look cool. That's it.

It might not even benefit 50 or even 10%.
So yes, may or may not be of benefit.

Absolutely, Kimber cables look great.
I own a couple of their USB cables.

- Rich

 

[Alex2507]

in passive biamping, the tweeter circuit has very little low frequency currents and the theoretical effects (or benefits if you prefer) of that is well documented.

Sold.

I have a 3-way speakers with an isolated tweeter. Currently I'm driving them with a rec'r and I cross them to subs. So between what you mentioned above and providing these 4 Ohm speakers with presumably more stable 4 Ohm power and a healthy dose of placebo effect, I should be back in a few days (after passive bi-amping) talking about how much air I got between my ears.

The other thing this does for me is get my 7 channel amp out of storage ... and it frees up a couple of monoblock amps that I now use for the subs. It's like a gear merry-go-round.

 

[PENG]

Sold.

I have a 3-way speakers with an isolated tweeter. Currently I'm driving them with a rec'r and I cross them to subs. So between what you mentioned above and providing these 4 Ohm speakers with presumably more stable 4 Ohm power and a healthy dose of placebo effect, I should be back in a few days talking about how much air I got between my ears.

The other thing this does for me is get my 7 channel amp out of storage ... and it frees up a couple of monoblock amps that I now use for the subs. It's like a gear merry-go-round.

I would definitely use the amp instead of storing it. You will hear better highs especially at louder spl, sorry for repeating so many times but the effects of Placebo is also well documented. Regardless, imo if you have the gear why not use it?