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

@grovergardner , In the Doge I really like NOS Brimar 12AT7sbut the reissue Mullards 12AX7s (when from a good source) are very quiet.  Reissue Gold Lions are fantastic yet I have had them grow noisier overtime.  
 

The Doge experience is really first rate. Wooden crate and boxing. Shipped to me inChicagoland in just a few days via DHL. 
 

Customer service abs communication is really responsive. 
 

Doge is a legitimate company owned and operated by its chief engineer.  This is not stuff you get on Alibaba or eBay.  

IMO Carver starts new companies so he won't have to be responsible for the cheap crap he designed while learning the craft and that's now breaking down.

I once sold a new Carver piece for $5 as is just so it would leave my store and never return. Just sayin.

Anyone who wants to sell a Crimson 275 for $5 let me know I'll cover shipping thanks.

@jbhiller I also use Brimar 12AT7s, and the Gold Lion 12AX7s.  No noise problems yet.  I *did* have an issue shortly after purchase--one channel developed distortion.  After some inital hassle (Covid was just appearing in China) I managed to get the schematic, and our technician at work repaired it for me.  It had some bad current-source transistors at the output.  He ordered a batch and replaced them all with matched ones.  So if you ever have trouble with yours I do have the schematic.

I just looked up Bob Carver's net worth on the net, $39.3 million.  Just a bit of information to add to the mix.