2. amps-preamps
  3. 167868-18279

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
jbhiller's avatar
jbhiller OP
1,387 posts
 

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.

mrdecibel
3,062 posts
 

@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

funky54
20 posts
 

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. 

jbhiller's avatar
jbhiller OP
1,387 posts
 

@funky54, Yes, I do think they need to just get to it and explain more about the transformers and testing. 

I have half a mind to open mine up to inspect the transformer situation.  

When will the sloppy guys at ASR be testing a legit one with a serial number?  They seemed to indicate that was underway and then they went silent.  

funky54
20 posts
 

My guess is it’s the same parts. Don’t care if he provided a cushion in slipping in the they were 35 wpc examples or not. I bet they are exactly the same parts. Same weight still..They had Mr. Carver there approving every step, they used the same schematic under Mr. Carvers’ supervision and both tested almost exactly the same.. in other words, they assembled things correctly. It’s a scapegoat replay saying the science was bad and they weren’t wirde4sound manufactured.. look at the back peddling already.. advertised as 75 wpc not its 75w for one channel but only measured without much bass… WHAT? I really don’t need any more reply or lies. The amp is a fraud. Maybe its an ok sounding 17 wpc amp. But it’s missing 4.5 X the power. Like that’s ok? It’s like saying “I brought $1000 of the $5000 I owe you, but you’re cool with that right?”

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