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.
jbhiller

Showing 9 responses by paulbottlehead

I posted the measurements firs to HiFi Haven, then to ASR, and I am happy to answer any questions about how I performed the measurements.  It was pointed out to me by a Carver dealer that the units I have are not serialized, so I went ahead and bought a new amp which should arrive any day, and I am taking that amp (unopened) to a neutral 3rd party to be measured independently. 

I would also note that I published a subsequent review of the ZOTL-10 to HiFi Haven as well, just as another reference point.

Mostly I am here to thank JBHiller for taking the time to pull one of the cans off his output transformers.  

I believe Bob Carver sold to Frank Malitz in 2019, and the amps I have here are from 2018 and one is hand signed by Bob as well.

The speaker ground vs. audio ground issue was brought to my attention and I tried the suggestion of connecting my FFT to the audio ground instead of the speaker ground and it made no appreciable difference.  Amir is also aware of this and I believe he will be posting his measurements very shortly. 

Power problems are apparent here.  Less than 2W available at less than 1% THD over 5kHz.  The 20Hz trace is also not so great.

Self-explanatory.

A 1kHz burst tone can let almost 75W out, but a 1-2 second tone cannot. 

Is it 60W sustained if that blew the fuse?

Does 60W at 1% THD/1kHz matter when you're looking at single digit power at 1% THD above 5kHz and down in the bass?

The subjective sound quality of the 275 has never been in question.  The specifications, however, are very much in question. 

That has definitely not always been the case.  Someone asked him about returning a 275 they bought from him two years prior and he said no on the 15th of January because it was outside the 30 day return window, then went in and edited that answer yesterday to say yes.

Regardless, this offer appears to not involve the dealers, an owner would send the amp back to Carver and get a refund from Carver.