The Difference Between Bi-amping and Bi-wiring

[cwall99]

He is talking about back EMF into the amp. Not really an issue. Personally I do like passive bi-amping in some cases. Back in the day I used to biamp with my Denon 5805 for my front towers. That receiver had a ton of reserve and it helped to drive my towers better than the single amp connection. However, I could have achieved the same results simply using a higher power external amp in a single wire connection.

Thanks Gene. Back EMF, now that I hear you say it, was indeed what he was talking about. Back in the day, you guys did a review of the Pioneer Elite VSX82-TXS, and while there were some issues with the video processing in the earlier products of that lone, they appeared to have sorted that out by the time I got mine...

but that's beside the point. It did seem that you guys were pretty impressed with the amp section.

I'd love to upgrade both my receiver (to separates) and my speakers, but I'm afraid that's just gonna have to wait.

I certainly don't think I'm doing anything detrimental to the sound, and while it may just be placebo or expectation bias, but it certainly seems as though my system is comfier than it used to be playing at volumes approaching 0 (that change in volume controls or labeling must've broken Nigel Tufnel's heart).

thanks again.

 

[PENG]

I went back and looked at the manual for my speakers, which are going on 15 years old now. But I thought this was an interesting quote from the manual.

"Many audiophiles recommend using two connecting wires instead of one because two wires share current through a greater conducting area (and for many additional reasons that we cannot verify but which we accept as true because we hear a difference in favor of bi-wiring)" And then they go ahead and give you instructions on how to bi-wire.

A couple of those claimed differences are actually easily verified if you understand (or go to the library) the related circuit and field theories but perhaps only in terms of existence. Most of the theories involved (e.g. Ohm's law, Kirchoff's law, Thevenin's theorm, Superposition theorem, Fourier theory, and some field theories as well, are within the syllabus at or below university first degree level but the issue is that the differences are in theory, not audible by normal humans. Any such differences, aside from the impedance, would also very difficult to quantify, ask a EE professor specialize in circuit and field theory and he/she may be interested in doing a research on it as they most likely wouldn't be able to quantify the differences easily either.

Again, if you are talking about audible differences, I guess we could think about comparing THD of 0.0005% and 0.0004%, if that.., not quite audible at all, or try comparing 12 awg and 10 awg speaker cable runs of 10 ft, same difference!

 

[little wing]

A couple of those claimed differences are actually easily verified if you understand (or go to the library) the related circuit and field theories but perhaps only in terms of existence. Most of the theories involved (e.g. Ohm's law, Kirchoff's law, Thevenin's theorm, Superposition theorem, Fourier theory, and some field theories as well, are within the syllabus at or below university first degree level but the issue is that the differences are in theory, not audible by normal humans. Any such differences, aside from the impedance, would also very difficult to quantify, ask a EE professor specialize in circuit and field theory and he/she may be interested in doing a research on it as they most likely wouldn't be able to quantify the differences easily either.

Again, if you are talking about audible differences, I guess we could think about comparing THD of 0.0005% and 0.0004%, if that.., not quite audible at all, or try comparing 12 awg and 10 awg speaker cable runs of 10 ft, same difference!

Peng, I will defer to you sir on all of the above. It's wayyy over my head. I just thought it was interesting that a speaker manufacturer, said they heard an improvement with bi-wired speakers. Considering it makes no difference to Infinity whether you bi-wire them or not.

 

[PENG]

Peng, I will defer to you sir on all of the above. It's wayyy over my head. I just thought it was interesting that a speaker manufacturer, said they heard an improvement with bi-wired speakers. Considering it makes no difference to Infinity whether you bi-wire them or not.

You can Google all of those I quoted, doesn't mean you can understand it all but will get an idea, most people only think Ohm's law, therefore focus on the impedance aspect, but it does involve more, however insignificant they are. Manufacturers are human, they can hear all sorts of things, most likely Placebo played a good part, but there could be many other reasons. Without knowing how they did it, it is hard to say why they heard the difference. If you remain skeptical, there is no harm trying, I did.

 

[little wing]

You can Google all of those I quoted, doesn't mean you can understand it all but will get an idea, most people only think Ohm's law, therefore focus on the impedance aspect, but it does involve more, however insignificant they are. Manufacturers are human, they can hear all sorts of things, most likely Placebo played a good part, but there could be many other reasons. Without knowing how they did it, it is hard to say why they heard the difference. If you remain skeptical, there is no harm trying, I did.

Yes, without knowing how they did it, it's hard to say. I'm not sure what they had to gain by saying they heard an improvement though. I did bi-wire my speakers years ago, and I thought they sounded better to my ears, but who knows, right? Did you hear a difference when you did it?

 

[PENG]

Did you hear a difference when you did it?

No, but it's done so I left them alone.

 

[sawyerthecat]

Horizontal and Veritical Biamping - an electronic crossover and four hafler amps

What is the the easiest way to answer the "does it make a difference question"
I am going to rule out hacking my speakers crossovers - and assuming any significant number of people would hack theirs.
It's not so hard to get a $100 audio crossover to split the highs from the lows
If you have four identical amps then you are ready to proceed with simultaneous vertical and horizontal biamping.
I have Paradigm Studio 60 V3 speakers setup which as many would know have posts provisioned for biamping. Strangely when I called the company they gave no insight or recommendation.
I normally drive with my Integra dtr-7.8 AV receiver taking the preamp to Halfer 240 SE (120wpc). I was thinking of spending $100 for an Ebay audio active crossover and connecting four hafler amps.
I did confirm with paradigm that the tweeter is by itself on one side of the crossover. I am thinking even though I will have the protection of the crossover I am going to need to be careful not to overdrive the tweeter.

Anyway this seems tobe the most aggressive but still straightforward, low cost (if you have the amps), and reversible test that one could do. With pages of chatter on this topic for over a decade I am not sure why I can't find 10 folks who have done this specific test.

I'm willing to move forward find a crossover and make four runs of 12 awg speaker wire. If there is any. I realize I should get some equipment and measurements as well REW or something. At that point this becomes more of a project costing $300 and 40 hours. So been thinking about this for a while - why haven't folks used this test setup, and if they have what did they say?

 

[sawyerthecat]

bump. I see this response at #16 which apparently raises an amp issue in not bypassing protecting crossover network when using an active crossover to split out the input to the amp to either high or low frequency only:

A problem might arise if each amplifier works into the cross-over network of its respective driver(s) in order that they only see their particular frequencies (both amps therefore working full-frequency). Generally an amplifier will then see a high impedance outside its driver's pass-band, which will be reactive to boot. Point is whether each amp will be stable under these conditions. One amp will be high-impedance inductively loaded at h.f., the other high-impedance capacitively so at low frequency.

 

[Swerd]

What is the the easiest way to answer the "does it make a difference question"
I am going to rule out hacking my speakers crossovers - and assuming any significant number of people would hack theirs.

If you use external active crossovers, you must disconnect each driver from the speaker's internal crossover. You don't have to remove the board, but you must temporarily bypass it. If you use both the external and internal crossovers at the same time, it won't sound right.

Those 4 binding posts on the back of the speaker cabinet are wired to the internal crossover, so unless you also disconnect them, you can't use them. Probably the easiest way is to remove each of the drivers, run separate wires from them, and route them out of the speaker cabinet through the port vents.

Paradigm Studio 60 v3 speakers (see Paradigm Reference Studio/60 v.3 loudspeaker | Stereophile.com) are a modified 2-way design, called a 2½-way speaker. There are two 7" woofers, one woofer (the lower black one) is rolled off by the crossover at 500 Hz, and the mid-woofer (kevlar or glass fiber?) works up to the tweeter crossover point just above 2 kHz.

The frequency response curve shown below is Figure 3 from that Stereophile review.

Fig.3 Paradigm Reference Studio/60 v.3, acoustic crossover (without grille) on HF axis at 50", with the complex sum of the woofer, midrange, and port nearfield responses (black). Also plotted are the nearfield responses of the midrange unit (red), woofer (blue), front port (magenta), and rear port (green)…

Several questions or problems come up:

In a 2½ way speaker, how are you going to divide the sound with your external active crossover? The crossover between the midwoofer and the tweeter should be easy, but what about the 500 Hz low pass filter for the black woofer? There may be a solution to that, but right now, I don't know it.

Because the midwoofer and lower woofer seem to have separate port vents (see above), it is possible that the cabinet is divided internally to provide separate compartments for each woofer. That adds to the complexity you will face.

You must protect the tweeter from getting unfiltered signals below about 1 kHz, or you risk damaging it. Right now the internal passive crossover does that. It should not be hard to set up the active crossover to do that, but remember that if you damage it, you have most likely voided the warranty.

Unless you are comfortable with assembling and wiring speakers, this may not be as easy as you hope.

But you can easily do your bi-amp test while using the speakers internal crossover and the existing bi-amp terminals on the back of the cabinet. Have you already have done that? (I didn't read this whole thread in detail.)

 

[RichB]

Maybe I missed something, but doesn't the internal crossover filtering also reduce the load that each amplifier would see?

It seems like you will get the benefit without the risk or tuning required to re-engineer crossovers that were properly designed by the manufacturer.

- Rich

 

[Swerd]

Maybe I missed something, but doesn't the internal crossover filtering also reduce the load that each amplifier would see?

Yes.

The amp driving only the tweeter will see high impedance below the crossover point. And the amp driving a woofer (in a simple 2-way) will see high impedance above the crossover point.

The signal going into the amp may be unfiltered, but the amps will pass little or no current outside of their respective pass bands. No current, no watts, no work.

 

[BigE-Dadda]

Ok guys, I hope this may not be redundant to you all but I have a question that I just can't seem to get a solid answer on. I'm run Onkyo tx-nr818 to polk 75t fronts, a pair of front heights, and two surrounds and a sub. I heard that Bi- amping was a way to really open up ur fronts. The polks handle 300w I'm at best pushing 100w to each given all the other channels I'm driving. I brought a Onkyo M 5010 amp that I was going to use to bi-amp my fronts. Please forgive me as well, I'm a Rookie so to speak, but don't have to knowledge most of you do. Should I use the amp to bi-amp or just do it through the receiver which it's capable of. But when you change setting in the 818 to ext amp it says I can only use it for sr fw, fh and if you bi-amp through the 818 it takes away fw and SB, and I think a zone or two which I don't use, right now But I don't want to lose my zones, as I just wired for outside entertainment. I'm at a complete loss, could some please give me some sound solid advice on whether to do or not, if to do then so how?? Thx In advance for any advice!!

 

[Ampdog]

Yes.

The amp driving only the tweeter will see high impedance below the crossover point. And the amp driving a woofer (in a simple 2-way) will see high impedance above the crossover point.

The signal going into the amp may be unfiltered, but the amps will pass little or no current outside of their respective pass bands. No current, no watts, no work.

This is what I partly tried to imply in my post #16, perhaps unsuccessfully so. Yes, as the quote says, no work. But - will the amp be happy to see the high load impedance outside their respective bands? Just outside the particular band that increasing impedance will also be a reactive load. Again, I know of cases where amps handling l.f. signals only, showed spurious h.f. oscillatory reaction, i.e. the load at h.f. was reactive to high and the included Zobel load came in at too high a frequency. As a test this can be easily determined by operating the low-band handling amp into a load of say a resistor in series with a suitable inductor. (Not all amplifiers are happy to work into a high/open-circuit load.)

 

[PENG]

This is what I partly tried to imply in my post #16, perhaps unsuccessfully so. Yes, as the quote says, no work. But - will the amp be happy to see the high load impedance outside their respective bands? Just outside the particular band that increasing impedance will also be a reactive load. Again, I know of cases where amps handling l.f. signals only, showed spurious h.f. oscillatory reaction, i.e. the load at h.f. was reactive to high and the included Zobel load came in at too high a frequency. As a test this can be easily determined by operating the low-band handling amp into a load of say a resistor in series with a suitable inductor. (Not all amplifiers are happy to work into a high/open-circuit load.)

I don't think you have to worry about open-cct and high impedance load as long as you don't crank the volume to force the voltage to go to maximum and there is no need to crank the volume any higher than the non bi-amp situation. Try leaving the amp on with nothing connected to the output, and there will be no issue.

 

[mardukes]

I hope someone is still listening to this thread who is willing to help out another wiseguy who knows little. I've got a Yamaha AVR (RX-V863) that "has" bi-amp capabilities. I just picked up a couple of Polk towers that come with 4 jumpered posts on each one. You've covered my first bewilderment -- how can simply removing jumpers get around the speakers internal crossovers? Answer: it doesn't. Throw in the fact that the Yamaha manual says nothing about the crossover between it's A and Bi-Amp posts, we're certainly not talking about anything active here.

• So, is this just bi-wiring++? It might be something more than just moving the jumpers from the speakers to the AVR because now we have different posts to which to wire. But did we just move the jumpers from outside to in? That makes it a more elementary question -- are there actually amplifiers for each set of posts? What are the electronics of a multi-channel amplifier? One big amp serving N sets of posts or N amplifiers?

• I don't get the bit about different impedance characteristics causing the work at the amp end being different. Apparently it's not like seven hoses hooked up to a manifold each having different nozzles at the other ends. That those loads are stresses absorbed (or causing failures) somewhere amongst the whole system. Another concept where I am lacking elementary understanding.

• Finally, what did someone mean that this puts your AVR at risk? That having these different impedance characteristics creates a risk situation?

  "In case of speaker with lower nominal impedance the risk of blowing the amp is greater (especially the mass market AVR amps)." -Sathishdholic @#7

md - hoping this doesn't look too busy for actual reading

 

[mardukes]

Every "authoritative" source seems to come to the same conclusion. Everything that passive bi-amping accomplishes can be done by just having a bigger amplifier. Which brings me to the same conclusion that Crutchfield avers (I paraphrase), you bought a 7.1 system that you're using for 5.1, so why not improve your "system" from 300 watts to 400 watts for the mere cost of a couple of runs of wire! Hellova lot cheaper than a 33% more powerful AVR. Besides, putting in those two rear surround speakers in are going to cost you those two runs of wire anyway.

Now, does that mean that my 2-channel mode will have gone from 100 watts to 200 watts per channel? Maybe Yamaha will give me that answer.

 

[Swerd]

Every "authoritative" source seems to come to the same conclusion. Everything that passive bi-amping accomplishes can be done by just having a bigger amplifier.

That is correct.

Which brings me to the same conclusion that Crutchfield avers (I paraphrase), you bought a 7.1 system that you're using for 5.1, so why not improve your "system" from 300 watts to 400 watts for the mere cost of a couple of runs of wire! Hellova lot cheaper than a 33% more powerful AVR.

This ignores a major point. Your AV receiver (and nearly all others) has one and only one power supply transformer. It has multiple windings to drive as many as 7 amplifier channels. All of these channels share the power from that one transformer.

It is similar to a 4-wheel drive car with one engine. It doesn't matter if you choose 2-wheel drive or 4-wheel drive, the engine can deliver only so much power. Your receiver's amp section can only deliver the power that its power supply transformer is capable of producing. It is up to you how many channels you use.

Now, does that mean that my 2-channel mode will have gone from 100 watts to 200 watts per channel? Maybe Yamaha will give me that answer.

No.

Read your AV receiver's manual carefully. http://download.yamaha.com/api/asset/file/?language=en&site=usa.yamaha.com&asset_id=35547

In the Specifications, on page 127, Yamaha says:

Minimum RMS Output Power for
Front, Center, Surround, Surround back
20 Hz to 20 kHz, 0.06% THD, 8Ω .................................... 105 W​

As required in the USA by the Federal Trade Commission (FTC), all audio amplifiers and receivers must be rated in watts per channel determined by the RMS method, at the audio range of 20 Hz to 20 kHz, at a stated % of total harmonic distortion, at 8Ω impedance.

What Yamaha failed to say is that the FTC requires that these power ratings be done while two channels are being driven. Your receiver is capable of delivering 105 watts per channel when two channels are each driving one speaker that is nominally an 8Ω load. (I personally believe the wording Yamaha chose is misleading, because it implies without directly saying so, that more than two channels were in use when the rating was measured. In the past, the FTC has directed that such misleading statements be corrected.)

If you use more than two channels, you can be certain that you will be getting less than 105 watts per channel. Just how much less is not known unless it is measured.

So to answer your question directly, you will not get 200 watts per channel from your receiver if you drive two channels. It will be 105 wpc. No matter how you wire your speakers, you will not generate higher power than the power supply transformer can deliver.

 

[haraldo]

I do have a hard time understanding why it would be better to buy two or three amps to do bi or tri amping .... As opposed to buy an amp twice or three times more expensive.
(Disregard active speakers, this is a totally different animal)

Gene, plz explain this to me, because I just don't understand ...

 

[mardukes]

Haven't heard back from Yamaha yet, but how about this statement from the Features section of that manual:

Built-in 7-channel power amplifier
◆ Minimum RMS output power (20 Hz to 20 kHz, 0.06% THD, 8 Ω)
Front: 105 W + 105 W
Center: 105 W
Surround: 105 W + 105 W
Surround back: 105 W + 105 W

What story are they telling here?

 

[haraldo]

Haven't heard back from Yamaha yet, but how about this statement from the Features section of that manual:
What story are they telling here?

It seems Tom Andry gotta have that amp......
http://www.audioholics.com/av-receiver-reviews/yamaha-rx-v863
Not sure what your question is about?