Focal Sopra with class A amp?

Not sure the Naim forum is the best place to find those with the experience you seek.

Sure why not. Class A are loved for lack of crossover distortion which should bode well with the lovely tweeters on the sopra. Valved class A even better as transistor class A has a reputation for being a bit cold.

If I were to try other electronics with my Sopra 3's I would do Lavardin, La Rosita or YBA.....but  they were voiced on Naim

Ralf, Sugden A21 is the only one I know. Good sounds with conventional speakers such as small Harbeths in not too demanding a room. Bigger Suggie for the Sopra 2s maybe? But then, do the bigger ones have the same sweetness as the A21? Sorry, bit out of my depth.

C.

What's the latest thinking?

Chris

try with jadis.

still open:-) i'll expand the scope with: Ayre, Pass, Octave, Lavardin :-)

You need to get hold of the impedance and phase data for the Sopras, then select a class A amp to match, should one exist.

Huge posted:

You need to get hold of the impedance and phase data for the Sopras, then select a class A amp to match, should one exist.

Hi Huge,

Very interesting; Please explain how to match speaker impedance data with class A amp data.

And what is the philosophy behind this ?

Peter

Class A amps are always struggling to keep the output devices in their Safe Operating Area (SOA), while still delivering enough current to the load.
See this:
http://www.audiomisc.co.uk/HFN/SCAMP/scamp.html

Form this it's clear that any speaker with low minimal impedance and/or high phase angles will demand a lot of current.  Whereas for class A/B operation that current demand can push the output devices out of the DC SOA, remember that for class A operation the devices have to operate at full current all the time:  So the system has to match the extreme current demand of a speaker or it will enter current clipping when demand exceeds the (class A maximim) current setting.  If the amp is designed for an 8Ω load and the actual load is 4Ω with a 45° phase angle, it will only deliver 1/16 power at that one frequency, and go into clipping if this is exceeded (or, dependant on design almost immediately violate the output devices time limited SOA).

As I understand this is a general statement concerning a risk of speaker/amp combination.

Power rating of the amplifier and efficiency of the speaker is also to be considered as a possibility to regain (part of) the 12 dB. IMO it will also be very dependant on the music being played (organ music with high energy levels in the lower frequencies corresponding with the phase-shift area might the most demanding) and the sound pressures that are appreciated while listening.

In case we hear distortions we don't appreciate, we turn the volume down.

I think we agree that the Focal Sopra is a speaker that can challenge to pump-up the volume and then a class A amplifier design will not be first choice.

Peter

Hi Peter,

Sorry, I simply don't know enough about the Focal Sopra 2 to be certain of any details.

All I can say is that many modern High End speakers are specifically designed for use with 'muscular' high end, high current solid state class A/B amplifiers like the NAP250 (or even the NAP300) that can drive severe (or extreme) loads without stress.  These types of speaker are just too difficult a load for any 'normal' class A amp to give of it's best.

Huge posted:

All I can say is that many modern High End speakers are specifically designed for use with 'muscular' high end, high current solid state class A/B amplifiers like the NAP250 (or even the NAP300) that can drive severe (or extreme) loads without stress. 

Not really, depends on speakers, amps, MATCHING,  i can give few examples of speakers where nap250 activate protection after one hour of playing, high volume, and also hi-fi speakers who works very well with less muscular amp like 200, and sound is wonderfull.

I'm unclear why a comparison between a specific regulated amp with overheat protection shutting down compared to an unregulated amp with no protection entering a marginal stress condition, should be relevant to the design criteria used by speaker manufacturers designing speakers for amps in the wider high end hi-fi market.

In terms of amp to speaker matching, please see the article I referenced earlier.

Ok, not the best comparison between 200 and 250, but 'muscular' high end amplifiers like 250 can stumble over many modern High End speakers.

Ah, I understand...

Not so much a comment on the speakers design (except to say that some can be extremely severe), more a comment that the 250's protection circuits can operate earlier than expected!

(Whereas a 200 being unregulated and unprotected, just accepts the short term stress and continues to play music with little or no noticeable effect.)

It's perfectly valid illustration (and explanation) of one of the different design properties of the 200 and 250 power amps.