Monoblocks vs Bi-amping

You'll want to read the post dated 2-19-09 in this thread, by the noted designer Steve McCormack. Among other things, he makes a strong case for why vertical biamping is generally preferable to the horizontal biamping arrangement you are contemplating.

Re the bridged monoblock possibility, if you don't necessarily need the added power capability that would provide, probably the only way to judge is by listening, as was suggested.

As you probably realize, bridged mode will cause the amplifiers to see the speaker impedance (6 ohms nominal, 3.7 ohms minimum at 90Hz) divided by a factor of 2 (in other words, the amplifier would see 1.85 ohms at 90Hz). Your amplifier can certainly handle that, but it would stand to reason that the character of its sound might be affected by that difference, in unpredictable ways.

Also, in vertical biamp mode both channels of each amp are amplifying identical signals, while in monoblock mode the two channels would be amplifying signals that are inverted internally, relative to each other. Again, hard to predict what the consequences would be, but it stands to reason that there would be consequences.

Regards,
-- Al

Hi Brian,

Let me preface this by saying that I'm no expert on Bridging or Biamping, however, I'm not a fan of Bridging. I do agree with Blindjim though, that bi-amping is usually associated with SS on the bottom and tubes on the top, to better taylor the sound towards ones preferences.

I wouldn't go out and by an Amp for the sole purpose of Bridging as the Plan. Now, if someone needed to do this out of necessity than I'm all for it.

The way I understand it, is that if you Bridge the Amps, then you will basically be reducing the load that the Amps could drive by 1/2 so if it could drive 4 ohms previously unbridged, then it will only be able to drive 8 ohms bridged, and I don't think that's as a good thing, unless you have 8 ohm minimal speakers to start with. My experiences although limited, have revealed higher levels of distortion, compression, heat, and clipping in bridged modes. I see that the Revel Salon 2's have a minimum impedance down to 3.7 ohms, so if you bridge your amps, then you may clip them with your particular speakers.

From the Spectron Website:
"Balanced Design: Musician III Mk2 is capable to operate both in stereo and mono (fully balanced) modes. While not necessarily an advantage in every speaker, Spectron monoblocks configuration triples the power and doubles the head room. The major advantage of this mode of operation, however, is noticeable improvement is dynamics and resolution of details in the music."

They say it triples the power, but then, wouldn't the amp have a difficult time delivering this power into a minimal impedance of 3.7 ohm speakers, which your bridged Amps will be viewing as a minimal impedance of 1.85 ohms.

I would think that in this case, bi-amping would be better, for less power output, but, improved power transfer to the speakers.

Rich

"...I would think bi-amping would be superior since the each amp would see a more stable impedance profile"

Hello,

Spectron claims that their amp is stable to the load up to 0.1 Ohm so this should not be concern to you.

I own B&W 802N and drive them with two Spectrons. Of course, as suggested above I tried them in both configurations. Unquestionably (for me , at least) monoblock configaration was much better then bi-amp stereo. No slightest question about it. If your speaker impedance is more gentle then extremely difficult 802 then you will be even better off.

Somebody above mention that minimum impedance of your speakers is 3.5 Ohm. If true then its great. The problem with speakers is that practically no customer asks and no speaker and amplifier manufacturer alike volunteer to describe... the speaker impedance PHASE behaivor and amplifier ability to deal with it. Its ain't easy...the demand for delivered power increase substantially.

Good Luck
Rafael

I've experimented with biamping quite a bit, and have had limited success. My first advice to you is if you're buying two amps anyway try different configs for yourself and see what you like best. That said, here's my own findings:

- I've tried horizontal biamping with multiple amps - identical SS amps, and SS for bass, Tubes for mid/treble. None of these were preferable to a single stereo amp (ie one of the amps used in the biamping), and all were materially inferior to a set of higher power mono-blocks.

- I've tried vertical biamping with identical stereo SS amps and have experienced favorable results - but it's speaker dependent. One set of speakers preferred the higher power mono-blocks. Another appear to be optimized for vertical biamping. You really, really need to read the thread that Almarg references - especially Steve McCormack's post.

- Finally, I know nothing about your amps, but have been told by amp Mfg's previously that stereo amps bridged to mono configs will NOT sound as good as running the amps in non-bridged mode. Parasound recommended running their amps in what they refer to as "single stereo" rather than bridged, saying that the power output is greater because the the single channel has full access to the power supply which will increase the rated power by about 30%. "Single stereo" is using only one channel from a stereo amp, and letting the other sit idle. You should consult your amp mfg about this as amps differ a lot. You should also consult your speaker mfg to hear what they recommend (ie high power mono, or biamp with 2 stereo amps).

You gotta take this on a case by case basis, considering both the amps and the load. Not just the minimum impedance but the reactance. For example, I've got bridged Plinius amps with 4 ohm Genesis ribbons but the ribbons are purely resistive so there is no problem. With the Spectrons and Revels, I would think monoblocks would be the better choice. The Spectrons were designed for this and benefit by going into differential operation.