bi amp imrpoving?


what the biamping will improve in general vs only one power amp??
thenis
Are you referring to passive or active biamping? With active systems(which I've been implemented, at home, since 1980), your amps are only required to process the bandwidth assigned them. This, for instance, relieves the mid/high freq amp of the burden of reproducing bass, cleaning up it's signal and increasing dynamics. You can also use tubes on top, where they best perform their magic, and SS on the bottom, for the best slam, speed and definition. Passive biamping provides less in the way of benefits, but is much less costly, and easier for most to implement correctly(given identical amps with which to work). Articles on both methods: (http://sound.westhost.com/biamp-vs-passive.htm)(http://www.padrick.net/LiveSound/Biwiring/Biwiring.htm)
i mean to use one poweramp for the bass and one poweramp for hight and mid. it must be the active methode.
In that case, if properly implemented and adjusted, you can expect to hear significant improvement in practically all areas of sound.
If you intend to do active biamping, you must (1) bypass or remove the crossover built into the speakers and (2) implement a custom-designed line-level replacement for it. This is not trivial as off-the-shelf crossovers will not do but it has become easier lately due to computer-based modeling of speakers and crossovers.

Kal
The downside is that it is hard to get it right. Often negating any benefit it would have brought.
Amen. That is what I meant to imply.

Kal
You can use one amp for bass and one for the highs & can still be passive. You can also use one amp for the left & one for the right. These differences are horizontal vs. vertical bi-amping.

Lots of articles around, such as this one
Kal - why do you need a custom crossover? What's wrong with a of the shelf active crossover like the NHT X2?

Mark
Active biamping is simple with as little a Dahlquist DQLP-1(still used by Marchisotto, to biamp the Alón Exotica Grand Reference system). I used (and modded in a number of ways) one over the course of almost 25 years, with a variety of systems, and excellent results. I might still have it, were it not for the present acoustic nightmare of a listening room a divorce stuck me with. A TacT RCS 2.2 has rectified the situation quite nicely though. There's an LP-1 for sale on AudiogoN now: (http://www.audiogon.com/cgi-bin/cls.pl?misceqal&1283407862&/Dahlquist-DQ-LP1-electronic-cr)
Once again, I say thanks to the experts who are willing to take the time to educate the rest of us. I haven't read the links in detail yet, but I surely will. I have a NAD C162/C272 preamp/amp combo driving a pair of Aerial Acoustics Model 7s. I have been considering bi-amping the Aerials with two Monarchy SM-70 Pros thinking that would be an upgrade over the NAD C272. It appears I need to learn more about bi-amping first.
Keep in mind that it is not REALLY necessary to bypass, or delete, the existing crossovers in your speaker system, to experience most of the benefits of active biamping. Those are primarily gained though the elimination of highs and lows being fed to the amps that don't need to reproduce them, via the low/high pass filter of the active crossover. That's providing that your speakers are equipped with a network that can be split by removable jumpers. Happy listening =8^)
"Keep in mind that it is not REALLY necessary to bypass, or delete, the existing crossovers in your speaker system, to experience most of the benefits of active biamping."

For MOST of the benefits of bi-amping, yes it is necessary to go to an active crossover. For one thing, by connecting the drivers directly to the amplifiers the speakers present a nearly perfect resistive load, which is much easier for an amp to drive. Bi-amping via passive crossovers has some benefit, but using an active crossover puts you in another world as far as engineering benefits.

Active crossovers are seldom used though, because an active crossover costs A LOT more to build than a passive crossover, you need multiple channels of amplification (perhaps as many as eight for two speakers), and it's better if the amps are engineered to the speaker system, with more watts in the lower frequency connections, etc. All of this conspires to relegate 99% of commercial products to passive crossovers, which are inferior.
07-10-10: Mhedges
Kal - why do you need a custom crossover? What's wrong with a of the shelf active crossover like the NHT X2?
That is because a crossover from a textbook (as must be all off-the-shelf designs) cannot compensate for the parameters of each and every set of drivers and cabinets. Even a choice of crossover slopes is inadequate to match the inherent variables of every hardware set.

For example, from the X2 page:
The X-2 is a general purpose active, electronic crossover. It mates with the NHT A-1, but can be used with any stereo or monaural amplifier. The X-2 is stereo/mono switchable and has a feature set designed to shape bass frequencies for optimizing room response. Note: The X-2 will not work properly with the NHT U2, iWS, or any Evolution series product,....


Kal
Most of the biamping that I've done, for myself and others, has been with planar mains(either Acoustat or Maggie), and transmission line woofers. To me; the greatest benefit to realize with biamping, is the cleaning up of the signal passed to the mains amp, via removal of bass freqs. That and the other benes mentioned in my first post, none of which would be minimized by the original system's crossover. If one were separating the drivers within a three way system, I'd have to agree that the woofer's crossover network would best be removed. The TS didn't specify the system he intends to employ, outside of mentioning, "bass, highs and mids".
Rodman, that is confusing two meanings for biamping. The usual meaning in most audio arenas is independently powering the drivers (or groups of drivers) within a commercial multiway system or by design of an active multiway system. In those cases, the bypass or removal of the passive high-level network (or its omission) is mandatory for the use of a custom external active low-level network. The reason is that you do not want multiple networks operating in the same bandwidth because they will interact in, often, unpredictable and unfortunate ways.

What you are directly referring to is the addition of (sub)woofer to an existing system. In that case, the built in crossovers are not operating in the frequency range where the external crossover to the (sub)woofer is operating. Thus, removal of the inbuilt one is not only not necessary, it is incorrect.

While the use of the term "bi-amping" for this is technically correct, it is not what is most often meant. The OP is terse to the point of obscurity but my interpretation is that he is asking about the use of additional amp(s) with an already existing system and not the addition of speakers.

Kal
Some of the above responses seem to imply that when "passively" biamping (i.e., using two amps on a biwirable speaker with no external line-level crossover added, be that active or passive -- "passive" biamping is actually a misleading/confusing term in that sense!), you don't get the benefits of relieving the upper-frequency amp from having to deal with the bass frequencies. Although passive attenuation (by the speaker's crossover) after the power output isn't exactly the same as filtering out those bass frequencies before feeding the signal to the treble-range power amp in the first place, there is still worthwhile benefit to be gained (at least in theory) by not requiring that amp to drive a woofer. The amp inputs may "see" the full frequency range, but the output section of the HF amp is not being called upon to deliver much current in the LF. This is of course in addition to the other theoretical benefits, like doubling the available amp power (assuming the top and bottom amps are identical).

I've only ever done passive biamping, but my feeling is that the main benefits of "active" biamping (again in theory - in practice, as has been pointed out above, all bets may be off under the wrong circumstances) are mostly in implementing the frequency-divider network at the low-power line level instead of the high-power speaker level. (Which, as was also pointed out above, relieves the power amps from having to deal with the more reactive load of a speaker's crossover -- in addition to eliminating the high power-handling requirement so the crossover can be miniturized, and removing it from the highly vibrational environment inside the speaker cabinet.) My guess is that this factor is much more significant than any benefit gained from restricting the frequency range seen at the power amp inputs per se. After all, to my knowledge no one has postulated a benefit in relieving the system preamp from handling the full frequency range by dividing the signal after the source and using two preamps...

BTW, I also have to disagree about the wisdom of using different and possibly dissimilar amps for the different frequency ranges (subwoofer amps excluded) -- in my (albeit limited ) experience, using identical or very similar amps (and cables) top and bottom is necessary for the sound not to risk becoming discontinuous, at least with speakers that are coherent/consistent top-to-bottom to begin with.
A small but important qualification to Zaikesman's post:
This is of course in addition to the other theoretical benefits [of passive biamping], like doubling the available amp power (assuming the top and bottom amps are identical).
This is a common misconception. In general, passive biamping cannot be expected to double the available power (which is only a 3db increase anyway), or to even come close to doubling the available power.

The amount of power that can be delivered to the speakers is most commonly limited by clipping, i.e., by the amplifier being asked to swing its output voltage to a level that is greater than it is capable of swinging. Since in a passively biamped configuration both amps are being fed full-range signals, the output voltage range they are required to swing will be no different than it would be in a single-amped configuration.

***AN IMPORTANT IMPLICATION OF THIS: If in a passively biamped configuration a low powered tube amp is used on top (for example), and a high powered solid state amp on the bottom, most of the power capability of the high powered amp will be unavailable and wasted. The power capability of the high powered amp that can be utilized will be limited by the clipping point of the low powered amp.***

Passive biamping will only result in an increase in available power to the extent that the internal voltage rails of the amps increase as a result of reduced current demand, and/or to the extent that power delivery of the single-amped configuration that is being compared to is limited by current capability, not voltage swing capability.

Regards,
-- Al
Don't see the point of using identical amps to biamp. Ya, it makes it easy but you're not taking advantage of mixing different characters. The result may be schizo but it's entertaining. Simple enough to tame gain with an attenuator. If you want easy power, just buy a good amp and forget about biamping. On the other hand, let's not forget this is a hobby and we can have fun. For serious, mind-melting fun and possibly endless playtime, there's DSP crossovers with RTA. Now, go out and run with those scissors.
Hi Al, although I think a potential increase in headroom of up to 3dB is nothing to sneeze at (and although I happen to be one one of those who feels that, other things being equal, more power -- and a realistic playback level -- is better for lifelike reproduction), it needs to be said that the audible benefits of increasing power capability, whether via biamping or just moving to a more powerful single amp, are not necessarily directly related to whatever is conferred in terms of sheer ability to play louder. One may never listen more loudly than before (and never bump up against the system's clipping or dynamic headroom limits) and yet still hear benefits from so-called "passive" biamping. My own feeling is that this results mostly from the (doubled number of) output devices having a more advantageous grip on an easier load combined with an effective doubling of the power supply (as well as the effective doubling of the cable guage and the elimination of possibly inferior jumpers, as in simple biwiring). Assuming your statement about the unchanged voltage output swing when the input remains identical is accurate (and granting that my technical [in]competence to discuss such matters is likely below the chart relative to yours), I'm not sure what bearing this actually has on amp performance or audible results, at least as compared to current output demands.
Hi Zaikesman,

I am in complete agreement with nearly all of your comments. And I certainly agree with the fundamental point that passive biamping, if well implemented, can yield significant sonic advantages along the lines that you and others have described.

However, I have seen several instances in the past in which the misconception I commented on nearly led to purchase decisions that would have been major mistakes.

Restating my basic points by way of examples:

1)Under typical circumstances, passively biamping two 50 watt amplifiers will result in little more than the equivalent of a single 50 watt amplifier, in terms of the peak volume level that can be generated.

2)Under typical circumstances, passively biamping a 50 watt amplifier with a 500 watt amplifier(!) will also result in little more than the equivalent of a single 50 watt amplifier (sic), in terms of the peak volume level that can be generated.

Best regards,
-- Al
I've been multi-amping professional systems for over forty years, as a sound technician, but- thanks for the tutorial. I'm NOT referring to subwoofers, as the ones I've done for home audio are crossed as high as 325Hz(10th order Butterworth). The object being to remove as much bass burden from the mid/high section of the system as possible. With the TacT RCS 2.2, in a system comprised of planar speakers and transmission line woofers; this yields a VERY coherent presentation. The first time I did this for a customer, was back in 1980. Of course, that was with the Dahlquist DQLP-1, at 200Hz, and not at 60db/oct. He had Acoustat Model IIIs, an Apt Holman, a couple Hafler DH-500s, the 10" transmission lines that I built for him, and was grateful/gracious enough to let me demo his system to others. My first personal biamped system was comprised of a pair of KEF LS3/5As, and separate KEF B-139 woofers crossed at 200Hz, with a custom DeCoursey high/low pass active network. That system sold quick, and the $$ was used to by a pair of Acoustats. =8^) "Biamping" IS the correct terminology for the application, and it works wonderfully.
Ngjockey wrote:

Don't see the point of using identical amps to biamp. Ya, it makes it easy but you're not taking advantage of mixing different characters. The result may be schizo but it's entertaining.
The point, at least in my case, is that biamping can get somewhat more and better sound out of the speakers, as compared with single-amping.

[My case: 88dB, 48" tall dynamic/reflex 3-ways having paired 6.5" woofers, in a mid-sized room, where the amps in question are a pair of 400w monoblocks (top) plus a 500wpc stereo amp (bottom) from the same (audiophile-quality) manufacturer, each with power supplies and SS output sections which are sufficiently beefy on their own. As you can see, a relatively modestly-scaled setup where there was certainly never any putative power deficit without biamping, yet improvements were still there to be had with it.]

My guess is that you and I are probably just after different things, sonically speaking, and/or may have very different kinds of speakers. I also find that doubling-up on physically more managable, more affordable (but good-sounding) amps is an easier way to go for increased power than jettisoning them in favor of much pricier and difficult to deal with gargantuan tanks.

Almarg wrote:

Under typical circumstances, passively biamping two 50 watt amplifiers will result in little more than the equivalent of a single 50 watt amplifier, in terms of the peak volume level that can be generated.
At the risk of repeating myself or seeming a jerk, IMHO the peak volume level that can be generated is largely beside the point. (And in any event that is, as you suggested, not only a function of amp power but also speakers and room, any and all of which may limit the max level. Conversely, where distortion isn't perceived as a negative, ear-splitting levels can be acheived with relatively "low" wattage, as proved by my 40w Fender Super Reverb 4 x 10" tube guitar amp.) In the scenario you describe, I would expect distinct sonic improvements at typical room-filling listening levels to be not only possible but entirely probable.
At the risk of repeating myself or seeming a jerk, IMHO the peak volume level that can be generated is largely beside the point.... Where distortion isn't perceived as a negative, ear-splitting levels can be achieved with relatively "low" wattage, as proved by my 40w Fender Super Reverb 4 x 10" tube guitar amp.)
That is true if the music has little dynamic range (meaning the difference in volume between the loudest notes and the softest notes). Most rock recordings fall into that category.

However, for music with wide dynamic range, such as well recorded, minimally compressed classical symphony orchestra, peak volume capability is most definitely not beside the point. On that kind of recording, power requirements for brief peaks can often be literally 1000 times or more as many watts as for the average volume level within the same work, which would correspond to a peak-to-average ratio of 30db.

Best regards,
-- Al
Sorry Al, I suppose I worded that poorly. I didn't mean that max volume levels are prima-facie beside the point -- I'm a big believer that realistic volume levels, and good sound at those levels, are required for convincing reproduction. (In fact I termed a phrase I call "absolute volume distortion" to describe listening at unrealistically loud or soft levels -- we all do it, but it's a form of playback distortion just the same). I meant that a relatively small potential increase in max volume capability (as you pointed out) is not the main reason for biamping, at least not for me. And lest my Fender amp analogy lead you to think I'm insensitive to uncompressed acoustic music's dynamic range, although I do listen to a lot of electric rock (a lot of it pretty lo-fi at that), and maintaining image independence within a group or massed context at high levels is important to me, in my view a critical test of whether additional power actually benefits a system's natural fidelity would not only be acoustic, but something like solo piano, or even solo acoustic guitar (a relatively quiet instrument at realistic volume settings, but one with which I am intimately familiar) and/or voice. If you screw these things up rather than making progress, then the ability to crank a little more in the bass is worthless to me. Besides which, now you've started making my argument for me! ;^)
We're not so different. You're preaching to the choir. I'm currently biamping with dual bridged Plinius SA-100's and a 1600W bass amp with separate active low and high pass filters. Don't ask how much that totals. Before that, I passive biamped Kappa8's from Mission 777's for the bass and Monarchy SE-100's for the mid/treble. Entirely different ages, characters, gain and feedback, despite both having the same wattage rating and being MOSFET. DIY'd a custom attenuator and got the best out of both. Going active could have been even better but that's a whole 'nother kettle of fish. That's just my own stuff. I've put together some wacky and extremely loud combinations for others.

Would I recommend biamping to the OP, after the way he phrased his post? NO. It was far too vague to indicate that he comprehends what he's getting into. Had he supplied some specifics or given any clue as to his competence, I would have been glad to assist. Maybe, I've just seen too many biamp threads.
Hi Ngjockey, in reference to your response, one of the reasons I go with very similar amplifiers (having basically the same gain) is that I prefer not to have to introduce outboard attenuators into the system, in addition to wanting as uniform sound as possible with seamless transitions between drivers. (I also use the same power cords and interconnects all around in addition to identical speaker cables.) I don't know from personal experience if this is as critical with an active outboard crossover (I do know that some have found it to be so), but as far as I can see I'm probably gonna stay 'passive' and never try going that route, for some of the reasons (among others) mentioned by various posters above. Not that I doubt the benefits of active multi-amping if done properly -- in fact, I've always found it somewhat surprising that there haven't been more high-end manufacturers designing complete integrated crossover/amp/speaker systems where each driver gets its own dedicated amplifier.
Would the use of a single amplifier with megawatt output, used with medium-efficiency speakers, negate any possible additional benefit of biamping?
Psag: Does the megawatt amp allow you to take more control over the system and optimize to your preference?
"Would the use of a single amplifier with megawatt output, used with medium-efficiency speakers, negate any possible additional benefit of biamping?"

In almost every case, yes.
Ngjockey: As I understand it(?), the benefit of biamping is to lower distortion, by providing enough power to each driver, regardless of its impedance. I believe that the goal of a company like Spectron is to build an amp with enough power to do that, obviating the need for biamping.

However, I do wonder if active biamping brings some other benefit. Irvrobinson, what do you think?
Irvrobinson: The reason I ask is because some amplifier designers (Behold for one) are starting to include active crossovers in their amplifiers.
Psag, that's different. I thought you were referring to passive bi-amping. IMO, active bi-amping can be big win, and a single megawatt amp with a passive crossover have to be of *very* high quality to compete. I think we always have to preface questions about bi-amping or multi-amping with whether we are referring to the active or passive case.
The question Psag poses could be taken, or rephrased, either of two ways: 1) Is there any advantage in going to biamping (by doubling up on identical amplifiers) if the single amp already in use is high-powered to begin with and the speakers are of average difficulty to drive (and let's also stipulate that the room size and listening volumes desired are around average)? Or, it could be taken to say: Is there any advantage to biamping (using identical amps) over just single-amping using a similar model (let's say from the same manufacturer) but whose construction and output specs are nominally twice that of the smaller amps?

Or put most simply: For an average system and listener, is there nearly always an advantage (in absolute terms and cost-effectiveness aside) in biamping where the power is doubled, regardless of how high it was to start with -- and is there an advantage in biamping where the power remains constant?

Putting aside for the moment the additional and important questions of whether we are talking about "passive" or "active" biamping (and assuming we don't screw it up if it's the latter), and also whether the amps are stereo or monoblocks (not to mention whether the cables in the starting condition are single- or bi-wired), based on my experience (again, limited!) I'd say the answer in the first instance would probably be yes -- even if the original amp or amps are high-powered to begin with and the demands are average, there may very well be an absolute advantage to be gained by doubling-up (amps + power). But then again, I'm an advocate for the notion that, other things being equal (which they won't necessarily always be), more power is better.

The second instance I can't address from experience, but I'd hypothesize that yes, even though the total power doesn't increase, there could still be some advantage to be gained in divvying up the duties so that the HF amp or amps don't 'see' the LF driver(s) -- much the same way most audiophiles believe that a pair of monoblocks can exceed a similar stereo amp of equivalent power per channel in part because an amp dedicated to each channel doesn't 'see' the demands of the other channel.

So, my opinion taken to its logical conclusion: In a multiway system, the best scenario would be to have an independent mono amp dedicated to each driver (I personally don't, and likely won't, have this), and you basically can't have too much total power, even with 'average' speakers and room/listening demands. Fire away...
Hello Psag,

#1
"Would the use of a single amplifier with megawatt output, used with medium-efficiency speakers, negate any possible additional benefit of biamping? "

Already been answered by Irvronisnon i.e. "In almost every case, yes "

#2
"...the benefit of biamping is to lower distortion, by providing enough power to each driver, regardless of its impedance. I believe that the goal of a company like Spectron is to build an amp with enough power to do that, obviating the need for biamping "

Various people claim various advatages/disadvantages of bi-ampling and I cannot go into all possible variations. Let me answer your question with your own equipment. I believe you have Coltrane speakers and two Spectron amplifiers which you use in nonoblock configuration.

a) Advantages of monoblocks over biamping.
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Spectron amplifier when used as monoblock is configured as FULLY balanced amplfier (i.e. it is two amps with positive and negative signals each). Due to the fact that it has very, very high part tolerance (and you paid for it !!!) and few more "small" things - practically ALL DISTORTIONS produced by each channel of amplification is canceled upon arrival at speakers. In other words you practically have distortion-free music. Most interesting is that it does not matter what design is used: tube, solid state class A or A/B, class D etc - almost all distortions caused by the amplfiier (regardless how different they will look on the scope) will be gone....and for that provilage you pay twice

b) Advantages of biampling over monoblocks.
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If your speakers have extremely difficult impedance behaivor, say in low bass area, then all kind of distortions will appear. Now, if you use monoblocks then these distortions will be spreaded over entire bandwidth and your ear is particualrly sensitive in midrange - so they will irritate you !
If you use bi-ampling then distortions due to poor impedance, as we use in the example, in low bass will be concentrated only in bass frequencies and your ear is substantially less sensitive in that area. this bi-ampling allows you to hear no distortion midrange and overall you will like sound much more.

Of course if you have active crossover then you have no choce as to use bi-ampling using two or three or four amplifiers as many do e.g. stereo at the top, two monoblocks at the bottom.

Simon
Thank you, and sorry for railroading this thread.
Hello Simon,
For an amplifier with two outputs on each side (such as the Spectron), is there a theoretical or actual advantage to using one output for the low frequency drivers and the other output for the high frequency drivers?
"Hello Simon,
For an amplifier with two outputs on each side (such as the Spectron), is there a theoretical or actual advantage to using one output for the low frequency drivers and the other output for the high frequency drivers?"

I'm not Simon, but there's no way the answer to your question would be yes. That's just bi-wiring, and if you are using a single cable of sufficient gauge there's no advantage to bi-wiring. (Apologies to those that believe otherwise.)
I tend to agree with Irvrobinson ...again but I would not be that categorical.

From my experience with developmet of latest Spectron and Elrod manufactured Remote Sense cables: there was no audible advantage of bi-wiring versus single wire and jumber (from hifreq -to low freq drivers) made of the same wire as the cable. May be in some circumstances it will be different but I suspect it will be rare

Simon
My tests with double runs of cable vs. various types of jumpers lead me to agree that one of the main (but often glossed-over) benefits of biwiring lies simply in the elimination of jumpers which are inferior to the cable being used. (FWIW, I never used to biwire before I started experimenting with biamping, and wouldn't call myself an advocate of it.) Another variable when single-wiring with jumpers can be which set of binding posts to connect to the amp -- right now I own two sets of speakers whose manufacturers recommend the opposite connections to the amplifier, one to the woofer binding posts and one to the tweeter, and my findings have confirmed that both are right for their own speakers and wrong for the other.

BTW, though I've never used or even heard a Spectron, my own amplifiers (both mooblock and stereo) do happen to be of fully-balanced/bridged topology (and are fed via balanced connections from a fully balanced preamp and DAC). These amps are always in this mode regardless of whether I'm biamping or single-amping, and I still find benefits in biamping.