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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
charles1dad's avatar
charles1dad
10,250 posts
 

I’m bothered by the view point that we should just gloss over the big covers over little 15w trannies or it making less than 25% of what its advertised to make because a few can still enjoy it with super efficient speakers in little rooms. 

Who is glossing over anything? Responses on this thread have been virtually unanimous in condemning the misrepresentation of amplifier output power? Even those who own/like the amplifier have been openly critical. 

Charles 

jbhiller's avatar
jbhiller OP
1,399 posts
 

+1 Charles1dad. 

@funky54 , you are correct in that misrepresentations are unacceptable.  If someone is buying a 75w push pull tube amp for 84dB speakers with nominal impedance of 3 ohms I doubt they would ever look at this thing. But the Company did market it as going into 4 ohms at 75w.  

I'm just not sure how this thing could test out near 75w with that 15w Edcor OPT in mine from MusicDirect.  I have my doubts. But Bob has pulled rabbits out of the hat before and it indeed sounds good. 

I have only 3 audiophile friends within an hour's drive. They all have sensitive speakers. Does anyone with less efficient speakers live in Chicagoland and want to have me bring the amp by for a listening test? You could bring speakers here too, yet that's more work than lifting this light amp. :) I'd be curious to hear it with more demanding loads. 

 

funky54
20 posts
 

@jbhiller That’s a great offer. I live in Florida so not feasible. As mentioned I came super close to buying this amp. My speakers are 86db 3 ohm and in a 30 by ..60ish room with 13 ft ceilings. It would have been a disaster. I came from two Carver C-500 amps vertically bi-amped. So while they were grainy on top and not the end of my road.. I was all bought in on Carver. Bitter sweet to see where its led. I was still keeping my eye out on used to see if I could pick one up, not now. Do love my current tube amps.. but there will always be that what if Changitis with this hobby. 

jbhiller's avatar
jbhiller OP
1,399 posts
 

I wish I didn't sell off my old PSBs, B&Ws, Monitor Audio, and hungry Totems. :)

atmasphere's avatar
atmasphere
11,778 posts
 

I'm just not sure how this thing could test out near 75w with that 15w Edcor OPT in mine from MusicDirect.

It won't.

As far as I can tell from the photos, that output transformer is a custom unit.

But its still a 15 watt device and will saturate when pushed beyond that level. The laminations in the transformer play an important role in how much power it can pass. The laminations are the magnetic core of the transformer and determine when it will saturate (no greater magnetic effect can occur). The wire plays a role too- it has to be able to handle the current at the power levels involved. But its mostly the laminations that say what power the OPT will be able to make. That is why higher power transformers are bigger and heavier.

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