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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
1,403 posts
 

@jjptkd  

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

HA!  

jbhiller's avatar
jbhiller OP
1,403 posts
 

Yes, Austinlawyer, Music Direct stopped selling them as well as an outfit on the East Coast, whose name escapes me at the moment. 

wfarrell
4 posts
 

 I have a crimson 275 and love the sound, it can drive the following speakers with ease, Bowers and Wilkens 803s which are 8 ohm 90 db, this was in my living room which is 15x25x9, I also drive them with rotel RB 1080 which has 200 watts per channel and sounds great, the crimson 275 sounded even better and drive them effortlessly, I also have carver amazing silver speakers which are  4 ohm 85 db and again the crimson 275 drove them with ease, I have read that the amazing silvers are hard to drive and some people use up to 1000 watts per channel to drive them, also have Ars Aures MI speakers which are 4 ohm 89 db and yes the crimson drove them with ease. My buddy has spacial turbos M3 and drives them with 400 watts oer channel of class D amps, he borrowed my crimson 275 and said he had to keep the volume at 1/4 which was less than the class D and indicated the sound was better.Tube amplifiers in general even with really low watts per channel seem to drive speakers easier than solid state rated at the same watts per channel. Maybe someone could shed some light on why (higher current) I am an electrical engineer but my half life expired about 41 years ago yikes lol. That being said the I love the way the crimson 275 sounds.

take care

paulbottlehead's avatar
paulbottlehead
13 posts
 

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

mulveling's avatar
mulveling
1,895 posts
 

My buddy has spacial turbos M3 and drives them with 400 watts oer channel of class D amps, he borrowed my crimson 275 and said he had to keep the volume at 1/4 which was less than the class D and indicated the sound was better.Tube amplifiers in general even with really low watts per channel seem to drive speakers easier than solid state rated at the same watts per channel. Maybe someone could shed some light on why (higher current)

Don't confuse power for gain, or volume position. Tube amps often have a relatively high sensitivity & gain. The Carver 275 is spec'd at 29dB gain. That's a lot for only 75 Watts / ch! It's a LOT LOT of gain for a 15 Watts / ch amp! Many tube amps lead with a V1 12ax7, and a lot of gain can come from that.

For comparison: the Parasound JC5 is also spec'd at that same 29dB gain - but with 400 Watts versus the Carver's 15? 60? The problem (for the Carver) is that the JC5 has a lot more "runway" before it runs out of juice. 

High gain in an amp is good when there's a LOT of power on hand to be tapped, or when the use case is for sources with low output levels (e.g. vinyl with a very low output cartridge < 0.2mV, or passive preamps, etc). In the modern era, a low power high gain tube amp doesn't make as much sense IMO.

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