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Peeking inside a Carver Crimson 275 Tube Amplifier

So, I just had to pop the hood on the Carver Crimson 275 tube amplifier. I was so curious as to how this little guy weighs so little and sounds so lovely.

  • The layout is simple and clean looking. Unlike the larger monoblocks (that cost $10k), this model uses a PCB.
  • The DC restorer circuit is nicely off to one side and out of the way. It doesn’t look all that complicated but I’m no electrical engineer. Why don’t more designers use this feature? It allows the power tubes to idle around 9.75w. Amazingly efficient.
  • The amp has very good planned out ventilation and spacing. No parts are on top of each other.
  • Most of the parts quality is good. There’s a host of Dale resistors, what look like Takmans, nice RCA jacks, heavy teflon hookup wire, and so on.
  • Some of the parts quality is questionable. There’s some cheap Suntan (Hong Kong mfr.) film caps coupled to the power tubes and some no name caps linked to the gain signal tubes. I was not happy to see those, but I very much understand building stuff to a price point.
Overall, this is a very tidy build and construction by the Wyred4Sound plant in California is A grade. I’m wondering a few things.

Does the sound quality of this amp bear a relationship to the fact that there’s not too much going on in the unit? There are very few caps--from what this humble hobbyist can tell--in the signal chain. And, none of these caps are even what many would consider decent quality--i.e. they aren’t WIMA level, just generic. This amplifier beat out a PrimaLuna Dialogue HP (in my room/to my ears...much love for what PrimaLuna does). When I explored the innards of the PrimaLuna, it was cramped, busy and had so much going on--a way more complicated design.

Is it possible that Bob Carver, who many regard as a wily electronics expert, is able to truly tweak the sound by adding a resistor here or there, etc.? Surely all designers are doing this, but is he just really adroit at this? I wonder this because while some parts quality is very good to excellent, I was shocked to see the Suntan caps. They might be cheaper than some of the Dale resistors in the unit. I should note that Carver reportedly designed this amp and others similar with Tim de Paravicini--no slouch indeed!

I have described the sound of this amp as delicious. It’s that musical and good. But, as our esteemed member jjss [ @jjss ] pointed out in his review, he wondered if the sound quality could be improved further still. He detected a tiny amount of sheen here and there [I cannot recall his exact words.] even though he loved it like I do.

I may extract the two .22uF caps that look to be dealing with signal related to the 12at7 gain tubes and do a quick listening test.
128x128jbhiller
atmasphere's avatar
atmasphere
11,762 posts
 

It's a video of a Suntan cap blowing up.

Those are electrolytics, quite different from what is used for coupling caps in tube gear!

 

jbhiller's avatar
jbhiller OP
1,389 posts
 

Yes, indeed they are Ralph.  It's just an exhibit in support of the point that Suntan caps are super cheap.  If a company's electrolytic blows up so easily how good can their even cheaper film cap be?  But for our education, yes a coupling cap is different than electrolytic AND this cap blowing up is not the same as the coupling caps in the Carver 275.  

The takeaway was supposed to be.... Why use Suntan at $.80 a cap?  Could they not use a better quality cap?  I mean what are you saving by using it versus a Wima or Vishay?  $5-10 per amp?  

jbhiller's avatar
jbhiller OP
1,389 posts
 

Status update--The ASR guys have their Carver 275 now and testing should occur shortly.  The odds do not look good that it will test much much differently on specified wattage, but maybe, just maybe, the distortion results will be better. 

charles1dad's avatar
charles1dad
10,250 posts
 

@jbhiller 

The takeaway was supposed to be.... Why use Suntan at $.80 a cap?  Could they not use a better quality cap?  I mean what are you saving by using it versus a Wima or Vishay?  $5-10 per amp?

Fair and intelligent question , ×hat are you really saving in cost?

Charles 

djones51
4,947 posts
 

That aside, even with its hundreds upon hundred of crystal clear watts (it tested ridiculously well), it couldn't beat out a nice Creek Evo Integrated of lesser power, driving all sorts of loudspeakers.

What do you mean by beat out? 

Buying on stats alone wouldn't tell me that.  Why ASR's zealot faction (not all of them) refuses to listen at all is beyond me.  

Buying on stats alone won't tell you which amplifier you might prefer. I've read a lot of posts on ASR and I'm not aware of anyone especially Amirm that says buy on stats don't listen. Now if you make a claim that one amp measures or sounds better you will be asked if that's a personal opinion applicable to you or a general statement about the amplifiers themselves, if the latter you will be asked for your testing procedure. That's what a lot of people get wrong about ASR. There are members there who prefer tube amps, class A amps, lousy measuring speakers and DACs but they don't make universal claims about those products they know they're simply personal preferences.

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