Yet another Survey: Biwire, passive bi-amp, active bi-amp?

[wgscott]

Do you

 

1. Bi-wire your speakers?

 

2. Passively bi-amp your speakers (and if so, horizontal or vertical)?

 

3. Actively bi-amp your speakers (what do you use for crossovers)?

 

In any of these cases, do you detect a readily audible improvement?

 

[bleedink]

But I am using B & W's...which aresupposedly made for that kinda thing. The main difference I notice is with deep bass levels which get routed to the floorstanders. The .1 in surround tends to feel a bit deeper. I confess the difference is subtle. For whatever reason I find bass to be slightly more relaxed but I've no way to do a blind test or reconfigure fast enough to be able to say for sure. The speaker connects are vertical. I also will note that aside from the speakers being great to my ears, they never sounded like they needed a sub--whether one has anything to do with the other ymmv.

 

 

[Audio_ELF]

I found B&W speakers generally respond well to passive bi-amping, though one better amp is better than two lesser amps: I.e. a Rotel RB1080 was superior to 2x RB1070 bi-amping was superior to 2x RB1070 bridged mono.

 

Eloise

 

PS. I would only bi-amp with identical or very closely matched amplifiers: IMO bi-amping with dissimilar amps is asking for a world of trouble.

 

[wgscott]

I was vertically bi-amping (passively, for now) with 2 identical amps, but one of them had a problem, so now I am bi-wiring.

 

I don't want to mess with the passive crossovers, but wonder if an active crossover would help at all.

 

 

 

[Audio_ELF]

Of course I didn't ABX blind test so they may have been identical and I just thought they were different...

 

[bleedink]

The definitions here. I thought passive bi amping could be done from one amp using unused channels...if this is merely bi wiring forgive me. I thought in the latter case you're using one channel to accomplish that. It is my further understanding that active bi amping meant you were using 2 amps to feed each part. I'm not claiming to be right--if i've misunderstood the concepts here could someone help me out? I am using my unused surround channels to accomplish this. I understood it as bi amping because you are using different amplified signal paths.

 

Yours in ever evolving ignorance!

 

I tried to use some initiative and use google but I'm afraid I'm no more clearer on the subject fwiw.

 

[Audio_ELF]

Bi-wiring: two cables run from 1 amplifier channel one to each terminal on the speaker.

 

Bi-amplified (passive): two cables run from 2 amplifier channels, one to each terminal on the speaker. Each amplifier channel is fed a full range signal.

 

Bi-amplified (active): two cables run from 2 amplifier channels, one to each terminal on the speaker. Each amplifier channel is fed from an active crossover so the bass amplifier gets only the bass signal and treble amplifier gets treble signal.

 

Horizontal and vertical bi-amping: horizontal has 1 stereo amplifier for the bass signal and 1 stereo for treble (either passive or active). Vertical bi-amping has 1 stereo speaker for left speaker and 1 stereo for right amplifier.

 

With many AV Receivers, you can configure spare rear channels (when using 5.1 rather than 7.1) to bi-amplify. Many stereo amplifiers have two sets of output terminals so you can bi-wire easily.

 

Eloise

 

[Codifus]

Passive bi-amping means you still use the crossovers in the speakers. It is exactly like bi-wiring except now you have 2 amplifiers, one for the highs, the other for the lows.

 

Active bi-amping means the crossovers in the speakers are completely bypassed/disabled. Instead of using them, an outboard electronic crossover is introduced between the amplifiers and pre-amp or DAC etc. The active crossover splits everything up: high frequencies to one amplifier which drives the mid-range and tweeter directly,low frequencies to another amp which drives the woofers directly.

 

Active bi-amping is very difficult to master because you really have to know the speakers and where to put the crossover point, adjust filtering slopes etc. Not for the faint of heart.

 

 

 

For those of you bi-amping passively, what cables are you using to split the signal to the amplifiers?

 

CD

 

[bdiament]

Hi wgscott,

 

I bi-wire my 3.6s.

I compared the same cables (Nordost Blue Heaven) both ways and find better bass definition and better focus throughout the range. Not "night and day" by any means (at least, not to my ears) but easily sufficient for me to have gone with the bi-wire setup.

 

There are two amps per channel but I wouldn't say I'm bi-amping because one set drives the Maggies (full range) and the other set is built into the subs (running from 30 Hz down).

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

 

[wgscott]

I've been told by various people in various places the following:

 

1. Bi-wiring does nothing that bridging the two sets of posts won't do, and the circuit diagrams are identical.

 

2. Passively bi-amping doesn't do much if anything more than bi-wiring, apart from providing additional power per channel.

 

3. Active bi-amping may or may not be an improvement, depending upon whether you bypass the passive crossovers and the active crossovers retain the relative phases of the passive crossover outputs as well as the same crossover frequency.

 

#1 strikes me as reasonable, I am not so sure about #2, and for #3 I still do not understand why it would be harmful to leave the passive crossovers in place. I understand why it would be less efficient for the treble amps, since it wastes power, but I don't get why that would matter (and presumably the attenuation match would help to maintain the proper gain match).

 

[bdiament]

Hi wgscott,

 

..."I've been told by various people in various places the following:

 

1. Bi-wiring does nothing that bridging the two sets of posts won't do, and the circuit diagrams are identical..."

 

I've said it before: Ask three audio folks a question and you'll get at least four different answers (five of which may be wrong). ;-}

 

Ultimately, I find listening for oneself is the only way to know whether you agree or not.

 

I can't find Jon Risch's site anymore. It had several interesting articles.

I did find a post of his though:

http://www.audioasylum.com/audio/cables/messages/4953.html

 

But again, there's nothing like hearing it for yourself to see how you feel about it.

 

Best regards,

Barry

www.soundkeeperrecordings.com

www.barrydiamentaudio.com

 

 

[4est]

1. Could have an effect as the signals "mingle" within the cable.

 

2. Although both amps are generating the same wave forms, there is little current being drawn from one frequency range.

 

3.On the right type of speakers, and done well as Codifus mentioned, it can make a HUGE difference. A classic use for this is with 2 way horn tweeters such as the Altec A7/VOT- an 800Hz horn crossed an octive too low at 400Hz, needing all of the damping it can get to help it hold together. Loosely, the passive crossover prevents the amp from having the tautest "grip" on the tweeter. We are talking flea power here too, under 5 watts. It is the control that is important, not the power in this example.

 

[Jud]

I just know you're gonna love this explanation:

 

Vandersteen strongly recommended biwiring on the Model 2Ces, so that's what I did from the beginning. I'm now considering making a DIY set of speaker cables using materials provided by Omega Mikro, manufacturers of the best cables I've heard. (See http://omegamikro.com/D.I.Y.html .)

 

Talking with one of the principals, he said biwiring would do nothing in this particular case. The website of Mapleshade Audio, which is a "sister" corporation to Omega Mikro, offers jumpers in place of biwiring and says the following:

 

"The usual jumpers that come with bi-wirable speakers - brass plates or Magnepan's U-plug - cause a most unfortunate degradation in sound quality. (Incidentally, half the improvement that people hear when bi-wiring is due to getting rid of these poor-sounding jumpers.)"

 

OK, so that's half the improvement. Where's the other half come from? (This will get a bit technical, at least by my lights.)

 

Vandersteen says biwiring helps eliminate modulation of the low level treble signals by the field that results from the high current bass signals. But the Omega Mikro fellow had this to say on that point:

 

"That is correct for the elements of the crossover (especially the coils) and for any non-linear elements in the field - including non-linear speaker cables. But what they are not telling you (or what they may not know) is the major source of this modulation is between the electromagnetic fields of the drivers and the crossover elements. Very minor modulation takes place in highly non-linear speaker cables - those with lots of dielectric and skin effect which are 'pumped' by the ever changing fields - the fields caused by the signals. If there are no non-linear elements present there is no modulation in the speaker cables."

 

(This "pumping" of the dielectric used on many cables is something that I've read about not only from Omega Mikro, but also on other cable manufacturers' sites, including Audioquest and Antipodes Audio. The latter's principal sometimes posts here. Signal through the cable stores energy in - "pumps" - the dielectric, which then releases the energy out of time with the original signal, causing time distortion of the signal, referred to sometimes as "smearing.")

 

Most Omega Mikro cables use air for the dielectric (the others use polyethylene about the thickness and appearance of the plastic in a sandwich bag) and the conductors are manufactured to minimize skin effect. Thus the problems biwiring is meant to resolve, are, according to the Omega Mikro folks, minimized in their cables to begin with.

 

So to summarize, better cables and jumpers should avoid the need for biwiring.

 

[barrows]

to KISS in these cases. Single wire, single amp. Different speaker designs respond differently to bi-wiring, with some speakers it may be worthwhile. Bi-amping can be a good thing, especially if one does not have a powerful enough amplifier; whether bi-amping helps will also be somewhat determined by how good the amps are, especially in terms of output impedance, and what kind of load the speakers are presenting. It is complicated. One potential problem with bi-amping is a loss of coherence-but back emf from the bass drivers of speakers can cause bad interactions (but usually only with poorly designed amps). Bottom line for me is: with a well matched, really good amplifier, and really good speaker cables and speakers, single wire and single amp will get the best results.

Active crossovers-this gets really complicated. I do not think most people here are speaker designers, and knowing a little about how complicated cross over design is, I could never design (which is what one is doing when they set up an active crossover) a crossover as well as a really good speaker designer. Plus, unless you have a MLSSA system and a really good measurement microphone, you cannot even begin to expect to get state of the art results designing your own crossover in an active system. Really good crossovers incorporate really sophisticated filters-elliptical slopes, assymetric crossovers, various notch filters to remove driver resonances, plus additional damping networks-it is really complicated.

 

[bleedink]

Your explanation was much clearer than the wiki I read. The discussion has already gotten a bit too technical for my nooB mind to take in! haha

 

[4est]

Barrows is correct in that it is most likely too complex for the typical user get their electronic crossover correct. It cannot be done with math alone, as there are too many factors at play simultaneously.

 

[bleedink]

I'll second (er, or third...) that!!!

 

I am not sure what method exactly above I am using...I thought I was clear reading Eloise's explanation then I read the next post and got confused. FWIW I have pretty full powered speakers for my rears, so I set the cross-over on my amp, and on my Oppo for 60...um is Hz? I know I am really showing off my ignorance here, forgive me! I am assuming this is NOT what you mean when you are talking about cross-over. This would mean I must be relying on the frontstanding B & W's to do the cross-over? How would I know what that is? Is there more that I would need to know in my particular set up to get better results or am I better off staying sorta dumb in this area and just letting the gear do the work...

 

[4est]

Most likely what is going on is that the rear speakers are being cut off at 60 hz(= 60 cycles per second) and the fronts are full range or cut at the .1 frequency (which I assume is aforementioned the 60Hz). If this is the case, you are not bi-amping in the context/sense of this thread. The bi amping would be a separation/split of the signal going to your mains' woofers and mid/tweets whereby you could eliminate the internal crossover components. Removing those is a big part of why you would want to biamp in the first place.

 

[bleedink]

The fronts are full range. I don't have, use, or need a sub. After a little research you're correct in that the 60 is cross-over for the rears and center to route them to the fronts. I have the highs coming from the front channels on my amp and the lows coming from the unused channels on my receiver. So if I am not bi amping what am I doing? Not being facetious at all...I am always curious. I assumed that having different amps (and in turn different DACs in my case as there is one for each channel) for the highs and the lows seemed to make sense. I'm not sure how I could accomplish the same thing using one channel and the connector on the back of the B&W's...

And just to play devil's advocate here what would I need to do to remove the internal crossover if I wanted to do such a thing?

 

[Audio_ELF]

I'm assuming that you are running a 5.0 setup and you have two sets of cables running from your speakers to the Yahama. In your Yamaha there is a setting to allow the unused (in 5.0/1) rear channels to bi-amp.

 

In this case you are running a passive bi-amp setup. Any crossover settings are to do with sending the low frequency part of the channels where you are using small speakers to a subwoofer.

 

Eloise

 

[4est]

Eloise is correct if I understand what is going on. It may be possible to split the signal digitally dividing the signals, but you really do not want to mess with it. Yours are three ways, and to do it proper you would have to tri amp. In the true bi/tri amp configuration you hook the amp direct to the individual drivers, getting rid of crossover parts completely. You do not want to do it unless you really understand what is going on. Most likely it will sound like crap and you risk blowing a driver with any mistake. It's advanced stuff, and even then it takes a long time to get it right.

 

[bleedink]

You are correct I am running a 5.0 set-up and do indeed have 2 identically sized cables running from the speakers to the Yamaha. I definitely enabled the bi-amp feature on the Yammy. Thanks for clearing that up. This is why I'd asked for a definition of terms as it appears I was correct the first time I said that I was passively bi-amping, though perhaps not in the strictest sense in that the signals are coming from the same amp. In response to your last paragraph, in my case the signals below 60 are being routed to the front speakers, not a sub. The settings are identical on the Oppo and the Yammy, since the Oppo is where I do my critical listening. Thanks again for your help in understanding! You have a way of clearing things up for those of us who are evolving in our educations.