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Question on bi-amping - Page 7

post #181 of 1039
Thread Starter 
What I've learned so far :

Bi-amping is about driving the highs and lows independently using an active crossover. With this set up you can use appropriate amplification for both highs and lows for improved efficiency, and less wasted power since the woofer can be driven with an adequately sized amp and an smaller amp can be used for the tweeter.

Passive bi-amping is sending full range signals to the highs and lows and so isn't technically bi-amping. What I've learned is that using identical amplifiers will result in worse efficiency as the amplifiers will limit available power to the woofer by driving the tweeter signal, robbing it, as it were. Since tweeters do not need nearly as much power as the woofer it is a waste of headroom as I understand it.

So it is a very inefficient connection scheme. That is what I've learned about bi-amping. I'm no expert and I've probably left out some details, but for a laymen like me, this is about as far as I'm going to get without cracking open a text book. tongue.gif

Edit : I looked up a few articles on the power distribution of audio signals for the highs and lows and that has given me an even clearer understanding about the whole tweeter/woofer power and why power is wasted with passive bi-amping.
post #182 of 1039
OllieS,

If someone already owns 2 (or 4, as the case may be) identical external amps and wants to passively biamp their speakers, there is really no (good) reason to advise against doing so. If someone was considering purchasing multiple amps just to passively biamp, though, the better option would be to buy 1/2 as many more powerful amps and wire the speakers conventionally.
post #183 of 1039
Quote:
Originally Posted by sivadselim View Post

OllieS,

If someone already owns 2 (or 4, as the case may be) identical external amps and wants to passively biamp their speakers, there is really no (good) reason to advise against doing so.

There is also no good reason to advise them to do so. They could always sell them on the used equipment market, or they could do what I do with my old separates, and store them in a nice closet.
Quote:
If someone was considering purchasing multiple amps just to passively biamp, though, the better option would be to buy 1/2 as many more powerful amps and wire the speakers conventionally.

I can see biamping to make your audio system to look more impressive or to obtain bragging rights. Some how I don't have enough time to waste to do that.
post #184 of 1039
Quote:
there is really no (good) reason to advise against doing so.
Quote:
There is also no good reason to advise them to do so.

I take the latter advice for 10$.
The other offer sounds like hogwash to me.
post #185 of 1039
Quote:
Originally Posted by OllieS View Post

What I've learned so far :

Bi-amping is about driving the highs and lows independently using an active crossover. With this set up you can use appropriate amplification for both highs and lows for improved efficiency, and less wasted power since the woofer can be driven with an adequately sized amp and an smaller amp can be used for the tweeter.

Passive bi-amping is sending full range signals to the highs and lows and so isn't technically bi-amping. What I've learned is that using identical amplifiers will result in worse efficiency as the amplifiers will limit available power to the woofer by driving the tweeter signal, robbing it, as it were. Since tweeters do not need nearly as much power as the woofer it is a waste of headroom as I understand it.

So it is a very inefficient connection scheme. That is what I've learned about bi-amping. I'm no expert and I've probably left out some details, but for a laymen like me, this is about as far as I'm going to get without cracking open a text book. tongue.gif

Edit : I looked up a few articles on the power distribution of audio signals for the highs and lows and that has given me an even clearer understanding about the whole tweeter/woofer power and why power is wasted with passive bi-amping.

Thx for sharing your lessons learned!
I've bookmarked this for future Q's on bi-amping.
post #186 of 1039
Quote:
Originally Posted by OllieS View Post

Edit : I looked up a few articles on the power distribution of audio signals for the highs and lows and that has given me an even clearer understanding about the whole tweeter/woofer power and why power is wasted with passive bi-amping.

I have what is just one small quibble. Power isn't really wasted, just not utilized. Perhaps it might be said that power amp capability is wasted, but not the power itself.
post #187 of 1039
Quote:
However the amplifier powering the woofer was still amplifying the full audio spectrum. It might have been isolated from the tweeter (which means nothing since the tweeter is not a signal source) but it was not isolated from the tweeter's signal.

Neither was the woofer amplifier isolated from the tweeter's signal. >

That's a lose-lose.

Quote:
The disadvantage to passively biamping is still sending a full range signal to both sets of binding posts. >

Exactly, and that is a significant loss. The power amp's ability to drive the woofer is diminished by having to amplify the tweeter's signal. The loss can be upwards of half its power capability.

Quote:
Removing the speakers passive crossover and adding an active crossover before the speakers allows you to manipulate the frequencies going to each set of binding posts. >

Exactly, and that can be a significant advantage.


I think it would be prudent to point out that the crossover should be placed between the Receiver/Pre-amp and the AMP. That may have been obvious to most, but the last quote "adding the crossover before the speaker" could be confusing to others.
post #188 of 1039
Quote:
Originally Posted by whoaru99 
I have what is just one small quibble. Power isn't really wasted, just not utilized. Perhaps it might be said that power amp capability is wasted, but not the power itself.

The power itself is not utiilised, which is another way of saying that it has been wasted. The power isn't dumped into a vacuum and hence wasted in that way, but it might as well have been. If the woofer or tweeter don't "see" the power and never will then for all intents and purposes that power has been wasted. Just a wasted opportunity, wasted potential.....

...wasted power.

wink.gif
post #189 of 1039
Thread Starter 
So anyways, I understand some of passive bi-amping but not all of it.

Why exactly are the full range signals routed to the highs and lows in this configuration? Can someone explain it in laymens terms? I know it has something to do with the passive crossover, but I don't know much about that.
post #190 of 1039
Thread Starter 
Have you guys ever heard of vertical bi-amping? Is that the same thing as just using separate amps to handle each speaker?
Edited by OllieS - 10/3/13 at 1:37am
post #191 of 1039
Quote:
Originally Posted by OllieS View Post

Have you guys ever heard of vertical bi-amping? Is that the same thing as just using separate amps to handle each speaker?

Yes, passive vertical bi-amping would be a separate amp for each speaker - one channel for the high frequency driver and the other for the low frequency driver(s). One advantage over passive horizontal bi-amping with different sized amps would be that there would be identical gain for both drivers (probably a real problem for horizontal bi-amping). Another might be better stereo separation though most modern amps have around -100dB crosstalk. Disadvantage would be that you would be "wasting" even more power on the tweeter and that you would need two identical more powerful / more expensive amps (advantage for retailers).

I never thought the reason for passive bi-amping was more power or headroom. Not saying that I believe it, but I've heard that it was to separate the woofer (and its "back EMF" which might cause small changes in the voltage at the back of the speaker) from the high pass section of the crossover. These voltage changes are supposed to cause small audible high frequency components which can pass through to the tweeter. The manual for my speakers says this (they also sell amplifiers).

Funny that everyone is also bashing active bi-amping - especially since most people advocate active bi-amping for subs - using an active crossover between the preamp and the amps for main speakers and subwoofer. One post even said active crossovers are no longer available - not true, I just bought a brand new one earlier this year. Of course, adjusting and blending at a sub crossover frequency is much easier than the crossover between drivers in a single, previously optimized speaker.
Edited by mtn-tech - 10/3/13 at 2:40am
post #192 of 1039
Thread Starter 
But how is that different from classic bi-amping? Wouldn't a monoblock be the same thing?

I read this here :

http://www.soundstage.com/synergize/synergize031998.htm
post #193 of 1039
Thread Starter 
Sorry, one last question. In order to use an active crossover do you have to remove the passive crossover from the speaker? So there is some modification to be done?
post #194 of 1039
Quote:
Originally Posted by OllieS View Post

Sorry, one last question. In order to use an active crossover do you have to remove the passive crossover from the speaker? So there is some modification to be done?

 

Yes you do. This is not something to be undertaken lightly. It would also invalidate any warranty on the speakers of course.

post #195 of 1039
Quote:
Originally Posted by goneten View Post

The power itself is not utiilised, which is another way of saying that it has been wasted. The power isn't dumped into a vacuum and hence wasted in that way, but it might as well have been. If the woofer or tweeter don't "see" the power and never will then for all intents and purposes that power has been wasted. Just a wasted opportunity, wasted potential.....

...wasted power.

wink.gif



Power itself isn't wasted. Power that hasn't been produced can't really be wasted in the literal sense. You seem to agree with that.

If you want to talk figuratively you can call it whatever you like. wink.gif
post #196 of 1039
Quote:
Originally Posted by mtn-tech View Post

Disadvantage would be that you would be "wasting" even more power on the tweeter and that you would need two identical more powerful / more expensive amps (advantage for retailers).

Yes and no.

Yes, inasmuch as most amps are built with the same power per channel so you're kind of stuck in that regard.

No, inasmuch as while people do sometimes use smaller amps on the HF section when doing a horizontal bi-amp, they're really hamstringing the caapbility of the system. Since the amp on the HF still tries to swing the full range signal voltage just as the amp on the LF, the HF amp will clip first if it is a smaller amp.

So, when you really get down to it, the power of the amps should be the same regardless if used in horizontal or vertical (passive) biamp. So, if done properly, as properly as you can do passive biamp that is, the higher cost factor of vertical biamping shouldn't be the case. Should be the same either way.
Edited by whoaru99 - 10/3/13 at 5:38am
post #197 of 1039
Quote:
Originally Posted by kbarnes701 View Post

Yes you do. This is not something to be undertaken lightly. It would also invalidate any warranty on the speakers of course.

I think optimally, probably yes, but it's not absolutely necessary. Running frequency limited signals though the amps should be more better ( wink.gif ) than running plain old full range signals. One thing you'd want to do is run the active crossover HPF and LPF a bit lower and higher, respectively than you probably would otherwise, so they didn't lay right on top of the speaker's HPF and LPFs.
post #198 of 1039
Quote:
Originally Posted by OllieS View Post

But how is that different from classic bi-amping? Wouldn't a monoblock be the same thing?

I read this here :

http://www.soundstage.com/synergize/synergize031998.htm

Are you now mixing/confusing biamping and biwiring?


Or, what's the question..."Wouldn't a monoblock be the same thing?"

Same thing as what?
post #199 of 1039
Quote:
Originally Posted by whoaru99 
Power itself isn't wasted. Power that hasn't been produced can't really be wasted in the literal sense. You seem to agree with that.

You seem to enjoy semantic word games. biggrin.gif You either use the power that is available or you do not. If you don't need the power then it is redundant. It is physically there but not physically used. If it is not physically used then it is physically wasted.

Big deal. wink.gif
post #200 of 1039
Thread Starter 
Quote:
Originally Posted by whoaru99 
Or, what's the question..."Wouldn't a monoblock be the same thing?"

Sorry, I wasn't thinking properly. I think all this talk of using one amp per speaker just confused me a little as with a monoblock you're using one per speaker too.
post #201 of 1039
Quote:
Originally Posted by goneten View Post

You seem to enjoy semantic word games. biggrin.gif

Perhaps you see it as semantics, I see it as an effort at being more technically correct.

The power isn't there because it hasn't been produced to any meaningfull degree in the out of band signal area. Vltage swing, yes, but no current due to the high impedance, hence no power produced there. So, it's not wasted power in the literal sense, it's simply wasted amplifier capability.
Edited by whoaru99 - 10/3/13 at 8:35am
post #202 of 1039
Quote:
Originally Posted by OllieS View Post

Sorry, I wasn't thinking properly. I think all this talk of using one amp per speaker just confused me a little as with a monoblock you're using one per speaker too.

If you were just biwiring then yes, one monoblock per speaker.

However, if you were going to biamp with monoblocks then you'd need two per speaker.
post #203 of 1039
IME vertical and horizontal bi-amping refers to the configuration of two stereo amplifiers used to bi-amplify a system:

Vertical = one stereo amp per speaker, with one channel for the lows and one for the highs.
Horizontal = one stereo amp drives the lows for each speaker, and the othe stereo amp drives the highs for each speaker.

Vertical allows you to place a single stereo amp near each speaker, reducing the length of speaker wire. Interconnect wiring is low-power and typically much less sensitive to length. However, you cannot choose say a higher-power amp for the bass and less for the treble, nor choose two different types of amps (e.g. SS bass, tube treble). The latter requires horizontal amping, but of course now you have longer speaker cables. The other trade is vertical amping eliminates crosstalk between stereo channels while horizontal eliminates crosstalk between bass and treble frequencies. You (I, anyone) could make a decent debate for either way. In practice I have done it both ways and can't say I have heard any difference with similar amplifiers. I did use a big SS amp for bass and smaller tube amp for treble for a long time in my system. Finding amps that blended well was a bit of a pain...

If you use four monoblocks then horizontal vs. vertical does not apply in this (my) scenario.
post #204 of 1039

In the Pursuit of excellent sound and I have achieve it with these Components:

Asus Essence STX sound card connected to Yamaha RX-A720 Bi Amped...B&W 684 tower speakers + B&W ASW608 subwoofer.

Spent 2700.00 and matched the sound of a 25000.00 system. I been at this a long time in the pursuit of a better sounding system

and before you guys present your argruments I suggest you obtain these Components. I'm no longer in pursuit of a better sounding

system because I have it. I did this solely for Music.

post #205 of 1039
Congratulations! I shall stick with my system, however, despite whatever flaws it may have with respect to your reference system. smile.gif
post #206 of 1039
Quote:
Originally Posted by Avalon East View Post

In the Pursuit of excellent sound and I have achieve it with these Components:
Asus Essence STX sound card connected to Yamaha RX-A720 Bi Amped...B&W 684 tower speakers + B&W ASW608 subwoofer.
Spent 2700.00 and matched the sound of a 25000.00 system. I been at this a long time in the pursuit of a better sounding system
and before you guys present your argruments I suggest you obtain these Components. I'm no longer in pursuit of a better sounding
system because I have it. I did this solely for Music.

What/Which $25000 system??? Inquiring minds want to know! wink.gif
post #207 of 1039

You want an example " Martin & Logan". The Asus Essence STX with its 124dB SNR makes all the difference connected to a good receiver with bi amp, tower speakers with bi amp terminals and a good subwoofer.

post #208 of 1039
Quote:
Originally Posted by Avalon East View Post

You want an example " Martin & Logan". The Asus Essence STX with its 124dB SNR makes all the difference connected to a good receiver with bi amp, tower speakers with bi amp terminals and a good subwoofer.

Perhaps so but it would sound the same if you were to remove the passive biamplification.
post #209 of 1039
Quote:
Originally Posted by Avalon East View Post

You want an example " Martin & Logan". The Asus Essence STX with its 124dB SNR makes all the difference connected to a good receiver with bi amp, tower speakers with bi amp terminals and a good subwoofer.

Got any idea what happens to the audio interfaces 124 dB SNR when the recording only has 75 dB SNR, the AVR has 100 dB SNR and the listening room only has about 70 dB SNR?
post #210 of 1039
Quote:
Got any idea what happens to the audio interfaces 124 dB SNR when the recording only has 75 dB SNR, the AVR has 100 dB SNR and the listening room only has about 70 dB SNR?

Those questions of practicality do not matter in the pursuit of audiophile purity.
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