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

"it just gets distorted at lower frequencies, probably leading to "punchy" bass. And Bob argues that most have subwoofers and won't be using them below 80."

Does this really help?

All anyone wants to see is the transformer & its label...

Hello Frank,

The curiosity centers on how is 75 watts of power derived from the lightweight diminutive transformers?

Charles

i am an owner of your carver 275 amp, actually like it alot, sounds very nice, wrote previously about my experience listening to it, which i enjoyed

my speakers are fairly efficient and not a hard load (spendor sp100’s at 89 db.w.m and 8 ohms) so my listening to music does not tax the amp and ask it for big power, even if it makes 15-20 legit watts it could still make good music in my setup

that said, i have also been kinda curious as to how the amp with its light weight (and thus small output trannies) would do a legit 75 wpc into real loads (or even an 8 ohm test load)

as a point of direct comparison, my audio research reference 75 is also rated at 75 wpc, also runs 4x kt120 power tubes, and it weighs 49 lbs... open the top, the sizable output transformers are right there looking back at you

 

 

Thank you for chiming in Frank.

It looks like that ASR folks could have been more scientific in ensuring they were testing an actual amplifier built in California by Wyred4Sound.

Now, this still leaves open the issue, what JJSS and Atmas-Phere are asking, how it is possible to get this output with so little weight?

I really don’t want to ship mine to ASR to test. I also don’t want to open it up and take it apart to expose the transformers. I’m curious, but not that curious, as I know from working on this amp that you have to disassemble so much to get to trans covers off.

@jbhiller, I enjoy this thread. I would use a hot glue approach ( I use clear door and window caulk ) to quiet down the mechanical properties of the cap and the mounting. These caulks have a sound, by brand, and of course, the amount used. Enjoy ! Always, MrD

So our answer is.. “here’s referrals that say it sounds great” and “we measured 75 to 90..” That isn’t proof. Stats should be provable. If I’m a huge heel, if I just don’t get it, ok. I’m not the brightest bulb, but I’d like to be shown how 75 watts per channel are consistently put out by this amp.

Then I’ll know I over reacted. I’d be the first one to say theres egg on my face.