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Bob Carver 275 Stereo Vacuum Tube Amplifier

SONDEKNZ

Well-Known Member
Thought I'd give this worthy thread on the BOB CARVER - Crimson 275 Stereo Tube Power Amplifier.

75W - 90W into 4-ohms is more than enough power for all of our speakers.
I just can't understand why there has not been more noise about this KT120 tube amp.
I'd also like to better understand how it's configured.
I'm guessing it is wired for Ultra Linear operation - with the amount of power on tap...
 
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Bob Carver has expressed a dislike of Ultralinear operation in the past, iirc, a reflection of his admiration of Stu Hegeman who didn't care for it in spite of his HK Citation II.:dunno:
 
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I have some interest in this amp for my main system (Tannoy Legacy Arden speakers (93dB, 8ohm), McIntosh C2300 tubed pre) in that it seems like one that my wife wouldn't easily destroy it given the tube life, low heat, and circuitry design.
Two questions I have that both have to do with sub woofers...what does the "Subwoofer" switch on the Crimson 275 do? It's not documented in the owners manual I found online. Secondly, could I connect my REL sub to the speaker outputs as recommended by REL? I do this with my current Pass amp and it works without issue.
 
K1,
Only the first 40 275s had the sub switch. It was a high pass allowing for a few more watts since frequencies below 40 hz were deemphasized. Turns out all 275s make 90 watts RMS anyway! As I expected, we immediately received communques about ground loops causing hum--common with some systems using subs.

Next, yes, your amp is compatible with REL, a company I helped launch with John Hunter. I love thier $4,000 sub!
Regards,
Frank
 
K1,
Only the first 40 275s had the sub switch. It was a high pass allowing for a few more watts since frequencies below 40 hz were deemphasized. Turns out all 275s make 90 watts RMS anyway! As I expected, we immediately received communques about ground loops causing hum--common with some systems using subs.

Next, yes, your amp is compatible with REL, a company I helped launch with John Hunter. I love thier $4,000 sub!
Regards,
Frank

Thanks for the details Frank, I really appreciate it. The Crimson is definitely on my short list.
 
It is puzzling, isn't it?
Not much buzz about these amps after an initial flurry of interest.
Curious, indeed.

We've never been able to keep up with the demand--even with the new factory up and running triple production.

Now, with the Rolls-Royce, Bentley, and Aston Martin owners club selecting our product to be the only American-made brand to be featured at their 50th anniversary celebration in London in 2021, and despite the fact that we have no dealers in England, when the pandemic ends, we’re going to have to be ready for even greater sales. Great Britain is about to have a new product. More on this below.

At almost no time since its birth, two years ago, were we able to ship immediately; there has always been a waiting list and there still is. I painfully remember the six-week waiting list. As a direct result, it would be irresponsible for me to pull a unit off production to send to a reviewer. in fact, Ken Kessler, arguably the Dean of British reviewers, is buying one after hearing it in United States. We are modifying the voltage as I type. Frankly, and ordinarily, he does not have to pay for samples, especially for review. In this case however, it’s for his own use. Ken is actually paying for the amplifier. if the buzz were any stronger, my dealers would be furious because of the constant back order situation.

Fortunately, with EJ Sarmiento, as my new partner, we will soon be building in much greater quantities. The factory builds many famous brands besides ours. Remember, even with a circuit board, the unit is entirely hand assembled in the United States. Finishing the new integrated amplifier, which could’ve been in the field a year ago but not for the pandemic recently, and working out the purchase of the company from Bob (which took six months of negotiations), has caused delays on multiple levels. We are also moving production on the more expensive point to point units to the new factory so there’s going to be waiting time on every model for the foreseeable future.

Before you bail on us, the waiting list on the 275 could be as short as two weeks, rarely longer than three. The four dealers we have on the Internet are ordering in large quantities so you may be able to locate a unit for immediate shipment. Check online please; and all four are decades-long dear friends and colleagues. All will guarantee your satisfaction. Sadly, as with nearly all businesses, the majority of our dealers are brick-and-mortar and shutdown. The Internet is keeping us not only alive, but healthy financially.

So why were we chosen for the British car anniversary Expo which will feature high-end watches, pens, custom tailored clothing and shoes, even estates, homes and villas? In their words, “even though the product is not available in our home country, we feel that as with our esteemed marques, your product combines a traditional approach with hidden unmatched technology inside; we trust our event might even help you launch the line throughout Great Britain ” Thus far, there are 1000 reservations from the wealthiest people on the planet, but to me, the marketing benefit outweighs the minimal sales opportunity this event could provide.

Lest you think I’m being arrogant, I was shocked at the phone call! Look at the gorgeous products from McIntosh, D Agostino and others (!) but the Brits did notice that we had the longest warranties in the history of the industry plus, it had to be handmade in the United States and, of course, it seems everyone knows Bob. In Bangkok, we were amazed when people came to our display area asking for Bob when they barely spoke English but we were also quite amused when people asked if I were Bob! I’m over 6 feet tall and I have hair! Poor Bob fell off his roof and he seems to have shrunk to about 5 foot five! Plus, he’s as bald as a cue ball!

Finally, don’t worry; thankfully Bobby is still with us as our chief designer and inspiration. We hope to introduce a handful of compelling new products over the next year and yes, Bob actually provided schematic diagrams on napkins!

Thank you so much for participating in the forum and providing an opportunity for our little company to update you guys on what’s happening. I hope to ship the integrated in 59 days
 
Bob Carver has expressed a dislike of Ultralinear operation in the past, iirc, a reflection of his admiration of Stu Hegeman who didn't care for it in spite of his HK Citation II.:dunno:
You are correct. Stu told Bob it was the greatest mistake of his career. Stu was forced to use that architecture by Sidney H. Bob prefers the other citation models, along with the tubed Marantz products and in case you didn't know this, the Crimson 275 is a tribute to Frank McIntosh, another of Bob's heroes who was greatly responsible for popularizing class A/B. I think Bob was slightly disappointed when he discovered the 275 was putting out over 90 W per channel continuously but we kept the 275 designation out of respect.
 
The Bob Carver 275 amp is more transparent than the MC352. However with digital sources it reveals the short comings of digital. This amp sounds its best with analog sources at least on my system.
Part of the reason is the golden near product which definitely has a detailed high-frequency character. We suggest you drop the bias to around 80 or slightly below if that bothers you.
 
Has anyone configured a pair of 275s to run a mono bloc set. If so how was it configured? How does it sound compared to the single stereo.
You may parallel the two channels ending up with somewhere around 150 to 180 watt mono. I can't remember the exact power when paralleled but it does improve the performance. I have a poor memory and since Jordon left, I only have Bob to turn to for these questions and his memory is far worse than mine. You may expect a slight improvement in performance narrowing the gap between the 275 and the 350 series. You end up with more devices and the output transformers will prefer a wider variety of load conditions.

We compare these two models--the 275 unparalleled (stereophonic, not mono) to the 350s at most shows. At virtually every show, no one can hear the difference, but at the last Tampa show, right before the pandemic, we sat quietly in the room with the lights dimmed after the show was over with no visitors in the room with the levels as close as we could match and you could hear the difference in refinement, but it's incredibly subtle. I believe Jim Clark stereo may have a diagram for the wiring which is quite simple. I recommend it.
 
You are correct. Stu told Bob it was the greatest mistake of his career. Stu was forced to use that architecture by Sidney H. Bob prefers the other citation models, along with the tubed Marantz products and in case you didn't know this, the Crimson 275 is a tribute to Frank McIntosh, another of Bob's heroes who was greatly responsible for popularizing class A/B. I think Bob was slightly disappointed when he discovered the 275 was putting out over 90 W per channel continuously but we kept the 275 designation out of respect.
Did Stu say specifically Why?
Fwiw, the Marantz were basically Mullard 5/20 with tapped screen Opts.
 
Did Stu say?? Oh yes, Pio, but I cannot remember why! My memory is deteriorating. I'll ask Bobby if I remember next time we talk. In fact, I'll email him now but he's not terribly comfortable with computers or cell-phones! :bigok:He's the perfect absent-minded genius! If I can get my dictation program working again (i'm a terrible typist), maybe I'll tell you guys about Bob's development and production of monoclonal antibodies for vaccines! He applies human physiology to the design of all our products--including the 275!
 
Bob's development and production of monoclonal antibodies for vaccines!
I'd be really interested in this information. My daughter had DIPG (brain cancer in the ponds) They are just now doing clinical trials with TCells. We would have oved that 5 years ago. DIPG usually happens to kids 3-11 but can happen to anyone. 3-6 months

I would love to know where your dealers are. I live in Valparaiso IN 46383. If you could direct me to somebody local that would be great. I'm look at the 275...I really like the Mcintosh 275 but since I've seen yours I've been in a holding pattern.

Brian Serafin
 
Did Stu say?? Oh yes, Pio, but I cannot remember why! My memory is deteriorating. I'll ask Bobby if I remember next time we talk. In fact, I'll email him now but he's not terribly comfortable with computers or cell-phones! :bigok:He's the perfect absent-minded genius! If I can get my dictation program working again (i'm a terrible typist), maybe I'll tell you guys about Bob's development and production of monoclonal antibodies for vaccines! He applies human physiology to the design of all our products--including the 275!
We'd very much like to hear about that, perhaps in another dedicated thread.
 
I received it yesterday and connected it to my main system down stairs in place of my McIntosh MC352. I picked 3 LPs to test with.
John Klemmer Touch - Original MFSL release in 1978 which still plays flawlessly.
Led Zeppelin I - Atlantic release in late 90s - This is one of the best re-issues of this album I have been told
Steely Dan Aja - Cisco Release

The John Klemmer album revealed details on the cymbals and percussion not heard before. John's Sax played clean with full authority. Drums and Bass revealed full authority and detail. Best I have ever heard this record.

Led Zeppelin I - Good Times Bad Times blew me away, this amp can play loud and is equally at home with Rock & Roll along with Jazz. Robert Plants voice never sounded better and John Bonham's drums slammed you against the wall. The triplets in the Bass Drum revealed every kick.

Steely Dan Aja - Probably the best I have ever heard this record as well. In the song Aja Wayne Shorter's Sax is in your face and never sounded better to me. Every detail of the mix of this album is revealed.

I do not intend to keep this amp in this particular system as I purchased it for my office system but it is temping to keep it there. It is a great sounding amplifier.

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mdewire, how loud is the transformer noise on your Crimson 275? Mine arrived today and I can clearly hear it buzzing from 7 feet away between tracks. For all the mechanical noise this unit makes, its strangely one of the quietest amps I've had in my system (meaning negligible amp hiss with volume up and nothing playing). The transformer buzz is so loud I'm wondering if this unit is defective.

Having owned a 60s era Dynaco, transformer buzz is not a new concept to me, but magnetostiction appears to be working overtime in this amp. I'd welcome your experience.
 
mdewire, how loud is the transformer noise on your Crimson 275? Mine arrived today and I can clearly hear it buzzing from 7 feet away between tracks. For all the mechanical noise this unit makes, its strangely one of the quietest amps I've had in my system (meaning negligible amp hiss with volume up and nothing playing). The transformer buzz is so loud I'm wondering if this unit is defective.

Having owned a 60s era Dynaco, transformer buzz is not a new concept to me, but magnetostiction appears to be working overtime in this amp. I'd welcome your experience.
You may have an issue because my unit has no transformer buzz at all. I would would call up their service department and let them know.
 
Can i buy the 275 also in Europe The Netherlands? And are you thinking about building an affordable speaker for it?
 
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