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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
mwjones's avatar
mwjones
37 posts
 

Charles:

I agree wholeheartedly on both points. That post was an oblique statement which I fleshed out moments late.

 

Mike

charles1dad's avatar
charles1dad
10,250 posts
 

Mike

👍

Charles 

audioman58's avatar
audioman58
4,200 posts
 

If you added $3-400 kin parts ,especially coupling capacitors , Vishay naked resistors , better wiring and Thst cheap Chinese crap has no business in a amp of this cost , rule of thumb as a ex Audii dealer only 25% of the cost actually goes into the build including all components, case , and packaging meaning $2500 including even tubes on a $10 k unit , that leaves very little for high quality transformer and chokes .too much greed for a lousy $300 in parts actually $200 or less dealer cost you could have had at least half way decent coupling caps like Mundorf Evo ,or clarity CSA ,that's just taking a piss in my opinion. 

paulbottlehead's avatar
paulbottlehead
13 posts
 

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.  

jbhiller's avatar
jbhiller OP
1,437 posts
 

So many great comments here Team. Thank you.

I’m so ambivalent. Before we/I move to my/our reptilian brains and go scorched earth.... If you will allow me...

Bob Carver grew up obsessed with hifi. He was a tinkerer-turned-PhD in physics. As a boy, he reportedly showed up at McIntosh diagnostic events. These were marketing and goodwill events where McIntosh would bring its big boy engineers and semi-founders out to cities across the country inviting America to bring in their hifi kit that had ground loops, crackling pots/switches, and so on.

McIntosh would help diagnose the visitor’s product. [Don’t you wish AXPONA would have this?] I’ve heard they certainly would, without putting down other makers, explain how things could be designed better in the customer’s unit in order to avoid the customer’s issue altogether. Kind of cool. They would also service Mac stuff at these events. They traveled the US. Very different than our world today where brick and mortar is dead, and I just buy crap  because I like to play with it and it gives me an excuse to hear more beautiful music.

At any rate, Bob Carver would (again reportedly) show up to these events on occasion and bring things in like the others. Yet, Bob, was so out there, that he was brining in his OWN IDEAS as a teenager. He once (again reportedly by my research) brought a Maxwell House coffee can into the McIntosh weekend diagnostic event. He told them he was working out a circuit and was close to Xanadu--I’m editorializing now. :). They refused to plug it in out of concern for safety and electrical hazard. That said, they were impressed with the circuit (not the coffee can).

Bob is a human. A genius in my mind. I’m not sure how good he was in business decisions or business acumen. But, I don’t know what the standard is to define that.

I think Bob sat down with that European amp designer and felt romantic about the days of Marantz, HK, Scott, even HeathKit, and many others. Bob knew many of those in audio history. I think he created an amazing little hot rod of a product. If I had to guess, I’d bet he thought we have come so far and sometimes we get lost in the simplicity of things that made good sound.

The marketplace is better for this Crimson 275 amplifier, regardless of whether it puts out wattage of 17, 35, or 75 (or even 90 as I think Frank M. has claimed at times). It’s a cracking little device.

Look, I sold a top of the line Primaluna because I preferred this little dude. He struck a spot that my 300B couldn’t reach. This thing works.

Now, don’t get me wrong. This is not a perfect piece of gear or "the best"--whatever that is. [Do you ever believe you’ve had a "best" anything? Best pizza, lover, beer, bourbon, day off, etc...].

It’s just a little amp that likes to boogie. Does your/my other amp like to boogie? I’ve had both the boogiers and those that won’t. Enough said.

Watch, this amp will be like that girlfriend or opportunity that I let escape due to forced apathy. 😏

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