Bi-amping: Good Idea?

[mdw]

I've noticed that some of the speakers I have been looking at have dual terminals to accommodate bi-amping. As I understand it, this involves the use of an active crossover between the pre-amp and the amplifiers. It occurs to me that adding another component in the system could have an adverse effect on the SQ. Any thoughts, opinions, or recommendations?

[davidbeinct]

Most speakers like that have an internal passive crossover. The idea is to bi- (or in some cases tri-) WIRE the speakers. This involves one connection to the amp positive terminal and one to the negative, but two to the speaker positive and two to the negative.

 

There is, like anything in audio, lots of disagreement over whether this does anything or not.

 

You can also passively biamp speakers like this. You can't actively biamp these speakers, even with an external, active crossover, without first removing the internal passive crossover from the speaker circuit.

 

I think Vandersteen was one of the first companies to try bi-wiring and their faq has some information:

 

Vandersteen Audio High End Speakers | Vandersteen Audio

 

Bi-wiring uses two separate sets of speaker cables to connect a single pair of loudspeakers to an amplifier. Coupled with a crossover designed specifically for bi-wiring, it offers many of the advantages of bi-amplifying the speakers with two separate amplifiers without the cost and complexity of two amplifiers.

 

There's more than that in their faq.

[wgscott]

The canonical answer is that bi-wiring does nothing, and passive bi-amping is essentially the same thing as bi-wiring.

 

If you passively bi-amp, with one channel to the treble/midrange, and one to the bass, does the energy in the treble/midrange channel that would otherwise drive the woofer (if you were mono-amping with mono-wiring) get dissipated as heat radiating from the crossover, or is that the amplifier channel feels a lighter load, as if you were mono-amping with the woofer disconnected? If it was the latter, it would indicate that passive bi-amping has some advantages over bi-wiring.

[wwaldmanfan]

I'm puzzled as to why respected speaker companies like Vandersteen and B&W would recommend biwiring if, based on the designs of their crossovers, it didn't improve the performance of their products, as the subject is so contentious amongst audiophiles.

 

I have done A/B testing, and feel that there is a slight audible improvement in SQ on my system biwiring my B&W's with this Furez cable.

 

http://Furez 12AWG 4 Conductor Speaker Cable Raw

[wgscott]

I bi-wired mine because I could, and then passively bi-amped, but never grew the 'nads to saw out my crossovers.

[Kal Rubinson]

I'm puzzled as to why respected speaker companies like Vandersteen and B&W would recommend biwiring if, based on the designs of their crossovers, it didn't improve the performance of their products, as the subject is so contentious amongst audiophiles.

I have heard that some companies do this to please their dealers and, functionally, there is no compromise.

 

I have done A/B testing, and feel that there is a slight audible improvement in SQ on my system biwiring my B&W's with this Furez cable.

I bi-wire to be above reproach. ;-)

[davide256]

Bi- amping sounds wrong; buying speakers that have customized internal amps and preamp fed crossover for each driver section sounds right

[monteverdi]

As long as the passive crossover parts are staying the benefit of 2 amps/cables are minimal. Only getting all these parts out of the speakers and using an active crossover (best digital) a major improvement can be achieved (but not many loudspeakers allow that). One alternative is modern active speakers but then one can not worry about cables amps, DAC!

[DigiPete]

Bi- / tri-amping is the professional way to go, but best done by the speaker manufacturer.

Preferably fully digital all the way to the speakers, ie with 100% lossless signal path.

 

It is beyond me why:

 

a) Any audiophile would suffice with passive X-overs.

 

b) Any audiophile would think he knows better how to match components than the pro's at the manufacturers.

 

c) Any audiophile would attempt his own Bi- / tri-amping unless the engineering is his hobby more than enjoying the music.

[JakovH]

OT. You've moved your sub6's on DigiPete?

[InfernoSTi]

There are many ways to bi-amp, some better than others. Active is best. Designed by the manufacturer is best. However, the principle remains that different drivers have different needs and you can achieve outstanding results by better matching your impedance and power demands with the right amplifier. If you have ever used hard to drive speakers, know that running out of gas makes everything sound bad...this is but one of the many possible solutions to that issue.

 

I happen to bi-amp only my woofers on separate baffles using subwoofer plate amps. However, I have not put a floor on my mains but naturally let them roll off at the bottom (not so hard with OB). If I had selected a multi-channel DAC instead of the Auralic Vega, I would absolutely send different signals each with a floor or shelf so that I wouldn't be trying to play under 40 Hz on my mains at all while my woofer baffles wouldn't be trying to play over 40 Hz (for example). This would make my mains far easier to drive than sending a full range signal (and I'm not really getting much below 40 Hz with a Fs of 36 Hz or so, anyway). It is my opinion that sending a signal below your speaker's Fs is going to demand a lot of power for not a lot of positive return (and maybe even bad things).

 

I would hesitate to dismiss the value of bi-amping because for some it is the key to great sound (DigiPete for example).

 

John

[YashN]

c) Any audiophile would attempt his own Bi- / tri-amping unless the engineering is his hobby more than enjoying the music.

 

Ha! But what if the two fields correlate?

 

Speaking in the purely theoretical domain, you are likely to get great results with bi-amping when you also use crossovers before your amp stage and then wire your amp directly to the drivers.

 

Some say the naive (or fool's bi-amping) bi-amping of just connecting two more wires with speaker-side crossovers still in place also can have an effect because of back-EMF or something like that if I remember correctly.

 

I could try the latter as the Totem Mites allow it, but have yet to do it.

 

I could also try the former one, but it's a bit trickier for me currently: firstly I don't want to experiment with removing things from the Totems and secondly, I probably could experiment with my Fostex Studio monitors but that will require a lot of internal disconnections/mods (amp + crossover circuits). I have the 4-way active crossover processing covered with the iMac, Audio Units and the 4-channel mode of the M-Audio FastTrack Pro.

[bluesman]

True bi-amp setups are rare today, because most add cost and complexity in excess of their sonic benefits - trying to get $25k performance out of a $2k amp and a $2k speaker system by adding a second $2k amp and a line-level crossover is a fool's errand. I think you can get better sound at lower marginal cost by simply moving up to a better amp/speaker combo.

 

The main advantages of bi-amplification are cleaner, more dynamic highs (because the power supply in the high pass amp doesn't have to drive the lows simultaneously), less intermodulation in the power amp stages (not a major consideration with today's products, but significant in products from my younger years), and a combined sound quality and level that was hard to achieve when watts cost big bucks - you could use a 100W bottom and a 30W top to get much better sound at higher SPLs than many high powered amps of the day could deliver. It was much easier to match the power amp to the drivers, as most SS equipment had a somewhat brittle, artificial high end while most tube amps had flabby bass. So I used to drive the bottom with a Crown DC, the mid with a Citation II, and the highs with a Marantz 8b, using a Nakamichi active crossover to split the line level signal out of the preamp.

 

I played with many amps through the 1970s and '80s. Then I got a Hafler 500 for the bottom and a Yamaha B2 for the mid and top. Much of this was through Infinity RS IIs and a series of home-builts, as I had my LS3/5as and Yamaha powered sub for fidget-free listening.

 

Downsides? Every crossover introduces phase shift, so setup is critical. Powered crossovers introduce noise and distortion, although the Nak seemed to be dead silent at any listening level I could stand. The added cabling and connectors are a portal for noise, a potential source of response-altering capacitance, and an obvious expense.

 

As electronics got better, I went to bi-amping and then a plain vanilla setup. The Yamaha B2 was a beautiful amp that I wish I still had. Even the Hafler 500 was a pretty fine piece that sounded great all by itself through a variety of speakers. And today's amps don't have those limitations at all - the complexity of multi-amplification just doesn't make sense to me when I can get the same sound quality from many combinations of electronics and speakers. My PrimaLuna power amp has really tight bass - so much so that I sold my Yamaha servo-amped sub. Even through my LS3/5as, there's enough bass to satisfy me on most program material in our second listening room.

 

So I don't think there's any place for true bi-amplification today. Modern electronics and speaker-level crossovers are excellent - if you want better ones, buy up. I just think there's too little to gain from bi-amping most systems to justify the cost and effort.

[wgscott]

If you passively bi-amp, with one channel to the treble/midrange, and one to the bass, does the energy in the treble/midrange channel that would otherwise drive the woofer (if you were mono-amping with mono-wiring) get dissipated as heat radiating from the crossover, or is that the amplifier channel feels a lighter load, as if you were mono-amping with the woofer disconnected?

 

Well?

[InfernoSTi]

Well?

 

Wouldn't that depend on the configuration of the amp? I would propose that it would need to be "dual mono" with separate power supplies to be useful. Further I would say that the real advantage is impedance matching and power delivery capability, something done best by different types of amps.

 

A better way if you are using two amps is to put the two woofers on left and right and the mids/tweeters on the other amp's left and right. That way power demands are more related to the power delivery capacity. Better yet is the then to put a low pass filter on the front end of the woofer amp and a high pass filter on the front end of the mid/tweeter amp. Don't make that amp work harder than it needs to and it will sing better for you.

 

I say this from my days of building tube amps and working on power supplies (and all the little tweaks one experiments with). Ultimately, you want woofers to be driven by high power SS amps and mids/tweeters driven by delicate little SET amps (or whatever your taste may be).

 

Or you could get a nice Pass Labs XA series amp(s) and be done...unless you bi-amp your woofers or subs like most of us do. Remember, those plate amps in your subs are bi-amps.

[mdw]

So, my take-away from these comments is, even though a speaker has dual input terminals, they still go through the internal crossover and bi-amping is probably a waste of effort. I MAY benefit from bi-wiring, but that is partly due to an effectively larger wire size, as well as separating the frequency loading effects on the cables.

 

This makes it seem like the dual terminals on the speakers is just a gimmick.

[wgscott]

My guess is they are primarily a gimmick. They don't really hurt anything, and if customers want them, and see that as a feature, it is easy enough to accommodate.

 

In my case, I currently "vertically" bi-amp with two (passive) class D amps.

 

One change i am considering is to put these two amp boards into bridge mode, and either (a) use one for each of the left and right woofer, and my internal Peachtree amp for the mid/treble, or (b) use each of them as a monoblock, and forget about bi-amping. If I run these in bridged mode, each can yield 500W. They are 120W each channel currently.

[monteverdi]

So, my take-away from these comments is, even though a speaker has dual input terminals, they still go through the internal crossover and bi-amping is probably a waste of effort. I MAY benefit from bi-wiring, but that is partly due to an effectively larger wire size, as well as separating the frequency loading effects on the cables.

 

This makes it seem like the dual terminals on the speakers is just a gimmick.

Passive bi-amping and wiring makes only sense if the crossover is designed that the mid/high and the woofer binding posts are completely not connected, i.e. a cross-over where low pass has no connection to high pass but that is almost never specified!

Increasing gauge has a small benefit but the connection of 2 cables with different time signature (like different induction and capacitance values) will be worse than a single cable!

[ilok]

I have found that bi-wiring changes the sound, over long period of time (months), I've come to the conclusion that bi-wiring hurts the overall cohesion, and is in fact detrimental.

 

(Slightly related, KEF found that bi-wire/amp(?) hurts the sound of the LS50 so they removed the dual terminal and went with a single terminal)

 

But really unless you got the clarity from a balanced power setup, you won't be able to tell the difference from most equipment changes. Balanced power really is a game changer.

[mdw]

But really unless you got the clarity from a balanced power setup, you won't be able to tell the difference from most equipment changes. Balanced power really is a game changer.

 

Please explain.

[ilok]

Please explain.

 

It reduces the noise floor that you didn't know you have by a miraculous 10 to 20db. Once the tide recedes, you end up seeing/hearing what's under the water all these years...

 

Try the used market, equitech stuff is pro level and very expensive when bought new. Another disadvantage is that you'll be able to hear the snake oils now...

[mdw]

I had to look up equitech. Looks pretty interesting; I'll have to keep it in mind after I get the rest of my system together.

[InfernoSTi]

Who here uses a powered subwoofer? If so, you are into bi-amping more than you know...

[wgscott]

I'm currently using two of these:

 

Class D Audio SDS Amplifier

 

This gives me four equal 120 W channels for (passively) bi-amping.

 

Would I be better off putting each of them into bridge mode, so that each is a 500W one-channel amp? (It also offers the option for balanced, so if I get a DAC/pre that can do that, it could be an improvement).

[DigiPete]

Who here uses a powered subwoofer? If so, you are into bi-amping more than you know...

 

 

Using three way active fronts and active sub.

I.e. quad-amping ;-)

 

And yes, I am very well aware!

All digital signal chain and room correction on top.

15 mono DAC's and 15 amps !!!

 

:-)