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

A little birdie told me that the amps subject of ASR's testing were, in fact, $600 kit amps--differing in quality from actual units sold with serial numbers. 

It doesn't come as a surprise that folks over at ASR believe they've uncovered a fraud.  However, surprise element aside, isn't it ironic that those touting science so heavily in high end audio likely didn't do their testing scientifically? 

For the love of all things sacred....If you're going to test things "scientifically" can you  at least (a) buy the unit from a licensed dealer; (b) note the serial number(s);  (c) make sure you know what you are talking about before posting alleged scientific conclusions.  

What's sad to me is that after reading all 13 pages of the ASR forum thread on their uncovering of "fraud", the confidence in their opinions never budges--even after a reputable dealer chimed in to clear some things up.  

For the love of all things sacred....If you’re going to test things "scientifically" can you at least (a) buy the unit from a licensed dealer; (b) note the serial number(s); (c) make sure you know what you are talking about before posting alleged scientific conclusions.

What’s sad to me is that after reading all 13 pages of the ASR forum thread on their uncovering of "fraud", the confidence in their opinions never budges--even after a reputable dealer chimed in to clear some things up.

Sad (And regrettable)? Yes.

Surprising? No.

I’ve visited that site in the past and was very disappointed with the content quality. They can’t even be thorough enough to be sure they have a true representative Carver amplifier. Yet can natter incessantly about conclusions. Real scientific method being practiced over there. I think not.

Charles

Carver’s own specs: 19 lbs for a Crimson 275 rated @ 2x 75 Watts?? That’s ridiculously lightweight, for a tube amp. That puts it in the class of a console-pull EL84 amp pushing ~ 15 Watts a side. No amount of Bob Carver "magic tech" talk can make that go away from my mind. The higher-end Carver monos also weigh only 44 lbs a side and claim 350 Watts! That’s very concerningly over-light, for the tube powers involved. The Rogue Audio Atlas weighs 55 lbs, actually hits its rated 100 Watts x2, and costs roughly the same as a Crimson 275. The Rogue Apollos weigh 100 lbs per side, spec 250 Watts, and cost similar to the Carver monos. Hell, I have a pair of Heathkit W5 that EACH weigh over 20 lbs. These are 25 Watts/ch KIT amps from freaking 1959. Their manual publishes detailed power response curves under load, and they literally kick the crap out of what ASR measured for the modern-year Carver Crimson 275! They sound really sweet, too.

Perhaps the proper production models contain the appropriately sized transformers AND a magic Bob Carver gravity-cancelling device?

Kinda silly.. doesn’t take an engineer to look up the transformer part number and see it’s only rated for 15 watts. . Doesn’t take an engineer to measure output at only 15 to 17 watts per channel.. pick on science nerds all you want. 
 

Why does the manual say the transformers are made from fictional steel from Greek mythology or Wolverine’s claws… no kidding right out of the manual. FROM CARVER, there it’s verified.

Two points, 

If you're going to test a component,  ensure you have the authentic model.

At the end of the day the sound quality is the most important parameter for an audio component. It's being purchased to reproduce music, so presumably you care how it sounds, No?

Charles