The output stage on Perreaux amps is based on Hitachi app notes. The Driver is definitely proprietry. I remember one of the engineers telling me that the amps sampled the rail voltage flucuations and fed it back into the input out of phase to reduce distortion. Does any oen know if Ive got this right or if its possible?
BTW in its day the SM3 was the flagship. PMF5550 was a behemoth, it took two people to lift safely and I think could deliver 2kw/ch into 2 ohm. It went 1850, 3150 and 5550, sm2, sm3.
BTW in its day the SM3 was the flagship. PMF5550 was a behemoth, it took two people to lift safely and I think could deliver 2kw/ch into 2 ohm. It went 1850, 3150 and 5550, sm2, sm3.
Luke said:........I remember one of the engineers telling me that the amps sampled the rail voltage flucuations and fed it back into the input out of phase to reduce distortion. Does any oen know if Ive got this right or if its possible?...........
Yes this correct there was a pot inside which was adjusted at the factory. Also the PCBs were symetrical and the power +/- cables feeding the boards were dressed whilst looking at a scope to achieve cancellation of any loop effects. There was a lot of attention paid to details.
Re: Hi nickds1!
Thanks
Any chance of a look at the SM3 docs? I have the schematic from Perreaux, but not the service manuals...zeonrider said:I have PMF 1850 & SM3.
Have full service manuals.
Thanks
fredex said:@ Luke Yes I worked there during SM2 days.
I'm just looking at the SM2 schematics and there is no DC rail sampling there - there is just one pot used to adjust the bias for each FET class A output stage.
There is a DC bias taken from the -45VDC rail (divided down to below -2.8V) applied to each long tailed pair, but nothing else.
Visually, its a very appealing preamp - nice PCB layout.
@ Luke Yes I worked there during SM2 days.
I worked there during the sm3 days Think I was only there for 6 months or so. So are you from Napier?
I realise the distortion cancellation was for power amps. I actually bought the 3350 reference when they closed shop.
brianco said:All I need now is the 2150!
Drop me a PM with your email...
nickds1 said:What's the difference between the SM2 & SM3?
Now I've looked at the schematics, pretty much nothing at all - mostly changes to the input switching and sensitivity...
I'll stick with the SM2 then!
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