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

Frank Malik (owner of Carver Corp) said he will provide responses to some of the questions raised in the forums about the amp. And so we wait

I hope he follows through and clearly explains the method for how the amplifier rated a 75 watt output. People deserve the facts.

Charles

Hello everyone,

In our three labs, we all get around 75 watts @ 1% or less, 90 @ 2%, etc. 

From Jordon Gerber, ex-partner, degreed physicist and co-founder: The units are about 75 to 90 watts depending on the measurement technique. . I kept a record of every unit. The power drops at low frequencies but given the way they slam with Kef Blade IIs, the innovative towers from SpeakerLab, and Wilsons is impressive.

 From Edward Suver (our WA tech support, QC and manufacturing supervisor (we have production and QC supervisors in CA as well): That's a crazy review.  The amps actually put out 90w or so at 1k into 8ohms, one channel, with .6% distortion. Every one if them made on my watch was tested and confirmed to work. Maybe 2 or 3 in 100 put out maybe 80 to 85w at that distortion, don't know why though. They put out clean 90W down to 80Hz, and distort more as it goes down, due to the lack of steel in the output transformers. When Bob initially tested it, the crazy thing is that nobody minded it. Reviews confirm that. The frequency response is flat, 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. For the output impedance, Bob wanted 1.7 ohm, and they usually measured 1.5 to 1.6. Never 2.5 or some BS.

From Speakerlab owner: "We've solidified our booth plan and will be premiering our Super SevenT-c's (the symmetrical tower version of our Super Sevens) powered by Bob Carver Crimson 350 monoblocks, and our Point2's powered by the new Bob Carver 275 Stereo amp. Source will be a Wolf Audio server run through a Mytek Brooklyn DAC, all wired with Kimber Kable Ascent and Base cables. Come see us next week at RMAF, room 2018!"

From Joe Parvey, owner, Wolf Audio Systems: "We almost always partner with Frank at shows. Their 350s and 275s outperform anything close in price. We sell them at our retail location.".

From Ken Kessler (the dean of British reviewers): "Wonderful; bought one for myself and I'm not selling it."

From Geoff Poor of Glenn Poor's AV--the largest BAT dealer in the world and the largest Wilson dealer in the Midwest. Geoff has consulted and worked with some of the most respected names in audio - Niro Nakamichi, Yamaha, MRC, Sony, & more - and in 1992, he was one of the founders of Dunlavy Audio Labs. In the spring of 1995, he left Dunlavy to become a partner at Balanced Audio Technology - a company he helped launch at the 1995 CES.: "

"Since we began showing his ALS (Amazing Line Source) loudspeaker system and his incredible 350 watt all-tube Raven mono-block amplifiers, the interest in Bob and his products has exploded. Both the ALS system ($18,500 with powered subwoofer) and the Raven mono-blocks ($9500/pair) represent incredible values - especially since they're built here in the United States. Another factor in their great value is the fact they are virtually bullet proof! It's so cool to be able to sell a high power, all tube system that is totally reliable.  To this date, we have experienced 100% reliability, and, based on Bob's design, the tube life expectancy is so long that the tubes and the mono-blocks are actually warrantied for 15 years!    

What if Bob could make a less powerful, and even more affordable, stereo version of the mono's?  Well, guess what?  He has, and we now have his new Crimson 275 playing in the same room as the Raven mono-blocks.  

The Crimson 275 is beautiful - looking and sounding - and is selling for only $2,750!  Using the same Tung-Sol KT-120 power tubes as the Raven mono's,  the same tube-saving "DC Restorer" circuit (that prolongs tube life by decades), the 75 watt/channel Crimson 275 is a genuine breath of fresh air in a world where most American-made electronics are simply too expensive for most of us.  The new stereo Crimson 275 is warrantied (tubes and all) for 5 years! It seems too good to be true, but it's not.  The Bob Carver Crimson 275 is a great amp!  And that's the truth!"

I'm hoping Bob will reply but he's pretty disappointed that no one from the blog called to discuss this. First time I've seen him angryThey seem to be $600 carver 37-watt Carverfest kits made by Jordon. He made 65 kits but we never manufactured them for sale to the public.

Remember we guarantee it will sound better than what you have or you get a full refund (subject to dealer policies on time frame, etc) and we've never had one returned. We've also never been able to keep up with demand. We may need a second warehouse! I'm meeting with Bob to discuss this on Thursday (two days from now).

Frank Malitz VP/Co-Founder

The Bob Carver Co.

847-668-4519

 

 

So you need to publish a spec you hold yourselves to and communicate to your potential and existing customers. This isn’t car audio. So what i am hearing is 75 1 channel driven  from > 80 hz to x at < 2% THD…. I would have Atkinson measure it for you. My two cents.

Jim

Hello everyone,

In our three labs, we all get around 75 watts @ 1% or less, 90 @ 2%, etc. 

From Jordon Gerber, ex-partner, degreed physicist and co-founder: The units are about 75 to 90 watts depending on the measurement technique. . I kept a record of every unit. The power drops at low frequencies but given the way they slam with Kef Blade IIs, the innovative towers from SpeakerLab, and Wilsons is impressive

Hello Frank,

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

Charles