bi amp imrpoving?

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! ;^)