Bridged Perreaux Amp question.

Just picked up a second Perreaux PMF 1150B, which is a 100 watt a channel Stereo Mosfet amplifier. The amp can be bridged with a switch in the back and according to the owners manual will thus put out 400 watts! Now, I know that my S/3100 will take most of the extra power, but, accoding to Perreaux I should "not operate this amplifier into loudspeakers whose nominal impedance is lower than 8 ohms when in the bridge mode." The S/3100 is rated as a 6 ohm speaker.

What would be my risk ? Would the amp or the speakers suffer ? Or, should I forget about it and run just one channel into each speaker, ala mono blocks ? Any comments would be much appreciated. I am really curious to hear what a difference either the extra wattage running in bridge mode, or running as mono blocks might make. I certainly don't need the extra power, but am always up for sonic improvements.

Thanks - Bernard

I don't think there is any risk to your amplifier or speakers. Try it at a reasonable volume. If you like it, turn it up a bit and monitor the temperature of your amp. As long as it is not over heating, then the load you are putting on it is acceptable.

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Originally Posted by mrbluster

I don't think there is any risk to your amplifier or speakers. Try it at a reasonable volume. If you like it, turn it up a bit and monitor the temperature of your amp. As long as it is not over heating, then the load you are putting on it is acceptable.

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I don't think volume level will be an issue as I know full well that I usually listen at under 1 watt as it is. 200 - 300 watts at 96db efficiency would be like some kind of death wish :blink:. I really bought the 2nd Perreaux as a back up. At the price these go for they are a real steal... sound really fine also. Kind of like the idea of trying mono/bridge just for the fun of it though. The one that I use now never even gets warmish at all.

Actually... just reading further in the owners manual it says "Bridging any amplifier, including the Perreaux will cause phase shifts affecting half its waveform. Despite the superiority of Perreaux switchable bridging circutry, we recommend bridging only for sub-woofer use or to power the woofer section in a bi-amped system." Sooo.. I guess there goes that idea. I will try running just one channel from each amp per speaker though just to see if it makes a difference worth hearing.

I assume the S3100 is not bi-ampable. If it were, that would be the way to go. Bridging may or may not sound better, it has the downside of decreasing the dampening factor which can effect the quality of the bass. Running one channel only (per amp) will definitely work well because you have now doubled the power supply for each channel. I recommend you try all your options and see what sounds best .

Actually it is bi-ampable... but this is where I get confused. I mean, if I were to do that then I lose the 1 power supply per channel, no ? would I not be better off using one amp per speaker ?

Hi Bernard,
Bridging your Perreau is of no real advantage, sure it may give you 400 watts, but it doesn't increase the Amps, and that is what runs louspeakers.
Perreaux even admit it when they say only use 8 ohm speakers, that should tell you.
Does your pre amp have 2 X pre outs? if so then hook up your 2 perreauxs' using 1 x power amp for bass L & R and the second for H/F L & R and see how that goes.
The term Bi amp is very loosley used it should read Passive Bi amp as you are using the internal X/over on the S3100.
I am at present playing with S2600 and I haven't got around to either Bi wiring or passively Bi amping, may be you can let us know
Regards
Michael

Yes, my Audio Note M2 preamp has 2 outs. I will try a few combinations, including Perreaux for the Bass and Jadis DA30 (tubed) for the highs. Too bad I don't have 3 outs or I could go mono's for the bass and DA30 for the highs :applaud: .. don't really want to get that complicated though. The one that interests me the most is one amp one speaker.. will let you know what I think. How are you liking the 2600 ? Should be a great 'little' transducer.:)

Bernard

Regarding bi-amping, I would suggest using one amp per speaker with one channel driving the high frequencies and the other for the bass. The reason I suggest doing it this way is because the bass side draws more power and this would distribute the load more evently between the two amps. Of course, this assumes you are using identical amps, i.e. the pair of Perreauxs mentioned earlier.

So you would run lets say both right outputs from the pre into the 'right' amp and then one channel to bass and one to treble ..

Correct!

I'll give it a whirl !

Let you know.

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Originally Posted by mrbluster

Regarding bi-amping, I would suggest using one amp per speaker with one channel driving the high frequencies and the other for the bass. The reason I suggest doing it this way is because the bass side draws more power and this would distribute the load more evently between the two amps. Of course, this assumes you are using identical amps, i.e. the pair of Perreauxs mentioned earlier.

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I'd agree.

Bernard
You cunning devil, run the Jadis on the top, you could either run one Perreaux on the L/F or two, so you have big fun infront of you.
You got me going so I (just for the hell of it ) I threw another length of wire at mine and Bi wired them, my Aragon Palladium 1K mono blocks have that provision, so I'll now go and have a listen with a cool libation
Regards
Michael

Perreaux= nice amp!

I just read this thread, and I didn't see any mention of the one HUGE benefit to bridging: headroom. True, you may not get more net output (the amp's overall THD will be multiplied..) but at low to moderate volume levels- the performance will (should) be improved. An increase in headroom can make a moderate system a wonderful system- instantly!

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Originally Posted by hapy._.face

Perreaux= nice amp!

I just read this thread, and I didn't see any mention of the one HUGE benefit to bridging: headroom. True, you may not get more net output (the amp's overall THD will be multiplied..) but at low to moderate volume levels- the performance will (should) be improved. An increase in headroom can make a moderate system a wonderful system- instantly!

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What about the phase shifts? Headroom is what my initial goal was.

Anyway.. so here is an update. I have been running the 2 Perreaux's quasi bi-amped vertically. In other words one channel mono, split separately into the bass and treble of one speaker in front of the x'over. I must say I really do like what I hear. Better separation, sound staging and bass control. The sound stage now is more square behind the speakers into the corners where as before it was kind of rounded. That might not mean much to most and maybe shouldn't but I really do like that effect ! I am loathe to try the bridged mode but eventually I guess I will just to see. Will wait a few weeks though to become accustomed to this sound first. Will let you know when I do.

Bernard

Not exactly sure what you are describing, but good is good... my feeling from personal experience and from others anecdotally is that bridging a stereo amp will virtually never be an improvement, if sonics is the goal... it can be useful if you need to squeak a couple of extra dB out of a system though.


Widget

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Originally Posted by Mr. Widget

Not exactly sure what you are describing,
Widget

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Ya, I thought that might sound a bit garbled :blink:... Ok, here goes again. I have the signal from the right outputs - I have 2 sets of outputs - of the pre-amp running into the right amp and then from that amp one chanel going to the treble and one to the bass of the right speaker. Ditto for the other channel. What I am doing is feeding each amp a mono signal.This is what MRBluster had suggested. So what I have in effect - I think - is two mono amps (kind of) with one power supply for each speaker. With a 96db efficient speaker extra db's and headroom are not much of an issue.

Bernard

Bernard,

I agree with Widget, I think you have the optimum configuration for the two Perreaux amps you are using. Skip the bridge mode test. It is unlikely to improve upon your current setup. "Sounds" like what you have now is quite excellent!