Carver Crimson 275 tube amp

PLguy,
Great analogy.  But for my running and golf shoe, I am 100% wearing loafers.  Truth be told, I have not heard anything but exemplary reports from Crimson owners.  That should come as no surprise as Bob Carver is a living legend in the audio world.  

I am with you I will not buy another pair of shoes unless they are self tying.

flasd,
What an insightful review, just excellent.  I don't hear much about this amp these days, but I do not doubt your ears.  I am very happy with my Don Sachs KT88, and personally -- and this is just me -- would not buy a tube amp without auto-biasing.  Thanks again for sharing your impressions of the Carver amp. 

UPDATE:
1) Ken Kessler, possibly the dean of the British audio press, just ordered a 275 for his own use.  
2) The Rolls Royce, Bentley, and Aston Martin Owner's Club selected The Bob Carver Corp products as the only US audio brand to combine the traditional values engendered in those distinguished marques with the most modern and unique circuit innovations and they invited us to participate in their 50th Anniversary Celebration in London alongside of the finest watch makers, yacht manufacturers, villa builders, etc. Audio will only be represented by two manufacturers--one British, and the Bob Carver Corporation. With 1,000 (wealthy) attendees already reserving a spot for the black tie dinner and presentations, the Queen will be in attendance. This is an astonishing honor. We are humbled. Dusting off my tuxedo!

Did anyone ever directly compare the carver 275 to the don Sachs Kootenay KT88?   

Carver 275 in the house. Love it-- Sold the Audio Research VT80-=-

I’ve owned a 275 for almost a year now - This amp overall sounds excellent driving my ML 11A’s as compared to several other amps I’ve tried including both tube & solid state... The ML’s are of fairly high efficiency due to 250Hz and below being driven by their built-in Class D amps (for the dual woofers).

Just to clarify, although my partner was able to duplicate, precisely, the sound of iconic Mark Levinson and Conrad Johnson premier power amplifiers, the 275 character is not based on someone else's amplifier. 

The original Silver Sevens were an assault on the state-of-the-art and despite what would appear to be a laughingly low retail price these days, they were among the most expensive amplifiers ever made at that time. The sound was determined by Bob, not by any other designer although friendly colleagues made suggestions that were always welcome. Ever since then, every model is compared to the top-of-the-line silver seven, using Bob's transfer function null tuning even as the Silver sevens continued to evolve.

The 350 series is modeled after the silver seven 700s/900s. So is the Crimson 275. At the risk of losing sales, and maybe even credibility, through these old ears, I cannot tell the difference unless I'm driving an extremely low sensitivity loudspeaker. 

Now, onto the lack of "buzz". When Sandy Gross, my old pal, introduced Definitive Technology, no one came to his booth at the CE show and there was no buzz. But the dealers, within months, were buying product as fast as he could make it. Yet, to people outside the industry, there was little buzz. His next endeavor, Golden Ear, went through the same gestation. Even when there was a waiting list, the general public knew little about it.

It's true now, with social media especially, that we expect a certain amount of buzz if a product is compelling. While our waiting list dwindled from six weeks to two weeks over the last months, we are back to three weeks again. I simply cannot keep up with the demand. I am constantly refusing samples to the magazine reviewers but also to forum members, all of whom know a lot of people who will buy my amplifier if they go to that person's house! We get requests like this nearly every week. If I can't keep up with the demand, I'm certainly in no position to offer review samples to individuals or even Absolute Sound Magazine who's been patiently waiting.

We've got about 30 dealers in the United States and at any given moment, 15 are angry at me! We're building 100 at a time and they're all sold.

So, is this product compelling? Can it stand on its own two legs without hyperbole from the Bob Carver management? Here's my answer: never buy a product without auditioning it. Never take someone else's advice; in many cases the person lacks experience or even worse, they are validating their own purchase decision by telling the world what they should buy. Ignore all specifications; they are all meaningless. I do tend to pay attention to signal-to-noise ratio (although anyone can say anything they choose with impunity) and naturally, we don't want to use a 50 W amplifier with a loudspeaker rated at 82 dB sensitivity. And don't take me seriously either; my hearing isn't what it once was, I could be a liar or maybe just a fool. There's no way for you to tell..

So listen and decide and here's what to listen for with the 275 specifically--tremendous slam on the bottom; fatigue free and liquid midrange and high frequencies; a larger than normal soundstage with more depth. All good tube amplifiers will give you a larger soundstage and more depth so some of these advantages are simply due to the nature of tube electronics because of their high output impedance and low damping factor which is a positive, not a negative. These are the most common comments I get.

Finally, I commend you to Glenn Poor's A/V website. Owned by Geoff Poor a principal at Balanced Audio Technologies for 22 years, you'll find a tribute to the 275 and it's probably the least expensive tube amplifiers he carries

dbass,
I got to the Carver room at Axpona and visited with Frank for just a moment, a real swell guy.  During my visit, the 350's were driving the speakers so I never got to hear the 275, but as Frank says, they are voiced to sound very similar.  The fit and finish on the amps were top notch.  I have shared my comments on Dan Sach's amp above and could not make a meaningful comparison as the Line Source speakers have quite a different sonic presentation than my Spatial Audio speakers.  

I'm terribly interested too! As an experiment, we tried the 275 on the Amazing Line Source loudspeaker which has a sensitivity of 82 or 83. At home, I use the 350s and wouldn't mind more power when I'm really cranking. I'm going to bring in a set of Silver seven 900s but that's one of the luxuries of owning the company-- getting samples I could not ordinarily afford. Now get this:

75% of the time, we were using the 275 and only announced it after playing. I also played the Bass and Drum intro from Nils Lofgren LOUD! In a normal-sized room, the 275 will actually drive the loudspeaker impressively.

I most humbly respect and welcome your feedback.
Frank

@whitestix - So what was your impression of the Crimson 275 @ Axpona?  I am interested in both Don Sach's Amp and the Crimson so very curious on your opinion of both.

Regards,

Thanks Frank. Looking forward to Axpona this weekend my friend. Stop and meet Frank in room 1215. He's been in the Hi Fi business since 1969. He has lots of stories about the product designs and launches of many of our favorite vintage brands and models. He's never at a loss for words and is fun to be around. Frank has seen all the industry changes and has interesting perspectives.
Jordon Gerber will be there. He can answer any technical questions absolutely, down to the physics level. Looking forward to meeting some forum members!

Very impressive response and I look forward to hearing the amp at APXONA later this week.  Two points of contention.   Don's amp is a bespoke amp handcrafted from stem to stern in British Columbia, with components sources worldwide, the best components possible at real world prices.   Second, if the bias setting on the 275 as stable as you say, then that is quite fine and takes out most of the PITA fiddliness of lots of tube amps.  In contrast, Don's amp has auto-biasing circuitry, but does not warrant the tubes in the same fashion you do, which is quite remarkable.  Frankly, for me, I will never buy another amp, not that I can imagine doing to now, that does not incorporate auto-biasing.  

I am huge fan of the KEF Blades and I am very impressed that the Crimson amp drives them splendidly, as you have said.   I can't wait to hear them at Axpona later this week! 

I'd better jump in here. This will be a very long post because I'm addressing several issues. At the outset, please accept my apologies. My eyes glass over when I see long posts.

I own the Bob Carver company along with Bob and our young partner, degreed physicist, Jordon Gerber. My name is Frank Malitz, I'm an industry veteran, I've worked with Bob for about 25 years, and I'm available through the contact utility on our website, seven days a week.

First the least important: Yamaha did not steal the design. They approached Bob after testing the Carver branded version and could barely believe it's performance. There was a proper contract in place. Like everyone else on this planet, even after the patents expired, no one has been able to backward engineer a Bob Carver design such as this and other models going forward, including the Sunfire product. That's why we had to set up a service facility for all these older models. We have never seen a Yamaha/Carver mag field amp in for service! Japanese companies used to avoid paying royalties under any circumstances. They would simply use a different design. In this case, there was no option.

But what Yamaha did was to produce thousands of units and not pay the royalties! I found it astonishing, having represented Yamaha for many years, that they would pull something like this. If the refusal to pay was in error, they would've corrected it. Instead, it went to international court were Bob annihilated Yamaha, one of the most respected companies in electronics. Go figure. By the way, in case you don't remember, Toshiba, in violation of international law, provided Russia with propellers for their nuclear submarines. When I was establishing Onkyo in the United States, Toshiba owned 20% of the company so we were very concerned. There were hefty fines. I also recall General Electric breaking laws as well and could never figure out why multi-billion-dollar entities bother with such behavior.

Now, let's talk about the Crimson 275. With a "normal" loudspeaker like the KEF Blade IIs, I borrowed at the recent Tampa hi-fi show, too lazy to bring our Amazing Line Source, with a claimed sensitivity of 92 dB and a measured sensitivity of 89 dB, the Crimson 275 sounded exactly like the Crimson 350s so we shut down the larger amplifiers for the rest of the show.

Even I was shocked at how hard the bass kicked, especially given the small woofers used in the KEF. There's a very specific reason for this: aside from the built-in headroom which is substantial-- they all measure around 90 W continuous, but they will do between 130 and 140 W with about 1.5% to 2% distortion but won't clip hard until they approach 160 to 170 watts! We used to call that peak power. This is especially compelling when one realizes the superbly designed 100 watt VTL monoblocks clip hard at 105 W! In fact, the VTL cannot drive the amazing line source loudspeaker at high levels. The 275 squeaks by, but my listening room, at 3000 ft.², does not permit me to listen to the 275 at the levels I prefer. We do use the 275, for example, at the Axpona show driving the ALS but it's in a small room.

In any case, the voicing on the 275 is based on the silver seven 900s using the transfer function null technique used in the infamous Carver challenge when our cheap amplifier matched the sound perfectly of the fabulous Conrad Johnson Premier IV and the Mark Levinson such-and-such. But now, we do not match the sound of anyone's amplifiers; we use the big 900s which Bob voiced according to his own preferences. To this day, I'm amazed how Bob can change a 20 cent part on an amplifier telling me, something like, "I'll just open up the top end a little bit" and lo and behold, that's exactly what happens. Even at his age now, his hearing and judgment are impeccable-- better than mine and I've consulted for most of the brands you guys know about :-). I just fool the manufacturers into thinking I know what I'm doing. Bob actually knows what he's doing. 

Now let's discuss bias: all of our amplifiers are fixed bias. Fixed bias is usually adjustable despite the "fixed" appellation. It's called fixed because of the nature of the stability of the bias circuit which allows for varying performance requirements more effectively than cathode bias while allowing for more power without burning up any resistors. The amplifiers come preset around 100 mA but Bob prefers 80 because he's a soundstage freak. On the old Sunfire Amplifiers, I preferred the detail to the larger soundstage provided by the hookup options. I couldn't have both. These Bob Carver tube amplifiers give you both.

Due to the DC restorer circuit, our bias, along with the collateral circuitry, is not only more stable than most other brands (all?) But it enhances tube life dramatically, hence the five-year warranty, including tubes. I'm confused about tube life on this model because the 350 series has a tube life of 46 years before degradation-- not failure. I would estimate the tube life, because we're pushing the KT 120s harder in the 275, to be "only" 26 years but I'll have to ask Jordon because he calculates these things instead of guessing like I do. 

For those of you who think this is all hyperbole, check out tube manuals from 1950 and you'll actually see statements like, "a well-designed circuit can provide for indefinite tube life". It was those manuals and Bob collecting old theater amplifiers from Western electric, Lansing, Western Electric and others, many of which featured their original tubes with thousands of hours on them yet measuring perfectly that inspired Bob to research bias in an effort to eliminate one of the main issues in tube amplifiers--tube life and heat.

Incidentally, there's not much in a tube type amplifier! You've got a power supply, a rectifier, some drivers to match impedance, and a tube. While this is an oversimplification, complexity often results in failure. Isn't it interesting that solid-state high-end amplifiers fail far more often than mass-merchandiser Yamahas, Denons, Marantz, etc.? In fact, even David Manley claims tube amplifiers should be more reliable than solid-state. He also believes, that a properly designed tube amplifier will be trouble-free and that's all he manufacturers. The worst of both worlds would be a hybrid-- tube and solid-state,c ircuits processing and amplifying your signal.

Interestingly, on the 350s, we use a military tube for this purpose-- the 6AL5, possibly one of the most rugged tubes ever used for audio. The tube manual, if you can find one old enough, lists bias control as one of its many functions and that was in the 50s-- the 1950s!

The 275 uses solid-state diodes for the same purpose yet I can't hear the difference. Other than that one exception, the 275 is all tube and yes, hand assembled even though it has a circuit board which is populated and soldered by hand by the guy that does the soldering for the Amazing Line Source which has 100 solder operations per tower. I'll never forget relaunching Dahlquist and my samples just didn't sound right. It took a few days, but we finally found the midrange was wired out of phase because they used clips for the speaker connectors. We are only using hand soldered joints since then.

The bias is not likely to change through the life of the unit. If it does, no big deal, it can take as long as 60 seconds to adjust if you're alone. With an assistant watching the meter, while you turn the pot on the back, it takes five seconds! Yes, you can tune the amplifiers slightly but the basic character will never change-- thankfully.

So what are the advantages of our amplifier over the Kootenay amp?
1) the DC restorer results in the most stable bias in the industry along with the longest tube life in history (incidentally, the warranty on the 350s is 15 years, not 10; we have to keep Bob away from all advertisements). Folks, that's a 20 times longer tube warranty than offered by fine people like McIntosh and Audio Research!
2) the amplifier repairs defective tubes. If you've not read our literature and wish to know how this happens, let's tackle it in a separate post; this is already way too long.
3) not only can you touch the tops of the mighty KT120s all afternoon and not get burned, the internal temperature of the amplifier is close to 50° lower than the competition-- about equal to the temperature inside your body. So unlike all other tube type amplifiers, it's not boiling itself to death! Another reason why we can give such long warranties!
4) unlike all other amplifiers, even those with multiple feedback loops, as far as I know, we are the only manufacturer to design a feedback loop specifically for dealing with the back EMF from the loudspeaker. Solid-state amplifiers cancel this out. Tube amplifiers, almost all, have the ability to listen to the room because of their high output impedance and modify their behavior to some degree. The problem is, with a low impedance load, i.e. four ohms, you end up with frequency response anomalies. With our architecture, any ambiance and depth that exists in the recording will be laid bare resulting in, well, greater depth and more openness-- a bigger soundstage. Nothing is synthesized; it must be on the recording. Yes, our amplifier not only listens to the room, which all tube type amplifiers with a high output impedance are capable of, but we do something about it.
5) I can't honestly say whether this is an advantage over the Kootenay but the product is handmade in the United States.
6) The unit has a five-year warranty, as we've said many times and that includes tubes. What's the warranty on the Kootenay?
7) The bias meter is right in the front--get a bad reading, get free tubes!
8) You can use the meter as a tube checker at full power! Check your pal's tubes too.

 Enough propaganda for one post but I did try to cover as many of your questions as possible. Thank you all for your patience in tolerating my wordy post.

Anyone heard the 275 on Zu ? 

Jim,
I am flying in from California to attend the show.  I look forward to meeting you and hearing the Crimson for myself. 

            The Crimson 275 will be showing at Axpona near Chicago April 12-14 room 1215. This is the largest audio show in North America. See axpona.com.  Bob Carver Corp and Jim Clark Stereo will be doing demos of the Crimson 350s, Crimson 275, Alchemy DDP-2 Preamp-DAC-Streamer, Wolf Audio Server and the Bob Carver ALS Loudspeaker System.

            A new, shorter, prototype speaker from Bob Carver will be shown. During development, the new speaker system has picked up the nick name - Half Stack. Although still a prototype, it will be present and ready to sing for you.

            We will be using the new Alchemy DDP-2 Preamp, DAC, Streamer. This Peter Madnick design is one you should hear. Even for those looking for more expensive products, at least hear the Alchemy DDP-2, and use it as a standard to judge others audio performance by. The DDP-2 isn't flashy or machined from solid aluminum, but the high end audio performance and outstanding value is all there.

It would be a pleasure to meet some of you and introduce you to the factory guys from Bob Carver Corp.. Jordon Gerber will be there. Jordon is a degreed Physicist. Jordon has been working beside Bob Carver for over a decade. Bob Carver holds a Phd in Physics and also a degree in engineering, although Bob never advertised his education (like Dr Bose).

Of course, you can always use our Satisfaction Guaranty and hear these products in your own home, anywhere in the mainland USA., without risk or restocking fees. Hope to meet you at Axpona.  
 Sincerely,
Jim 

Thanks for the question. There is a single potentiometer on the back panel. It has a slot for a small standard screwdriver. You adjust it and read the meter on the front panel.. After that, it will repeat the same bias setting each time you use it for years. It could vary with incoming line voltage, but that is normally very minimal. Basically, set it and forget it.  

Great to learn that the bias setting in not much vary over time.   How do you actually do the biasing.... does it entail using a small screwdriver to adjust a potentiometer, confirming the correct mA setting on the meter on the front.  If so, where are the potentiometer located?  On the top of the amp or on the back.  Is it done sequentially for each power tube?  That is what I am getting at.  Thanks. 

A question to Jim Clark. It is not clear how the biasing function on the Crimson unit works.   I am guessing that one would not need a voltmeter for biasing, but it doesn't appear as though it has auto-biasing.  

Can you explain the biasing procedure?   Thanks.

The proceeder above is correct. Generally the bias is set close from when the amp was ran during burn in. After the amp warms up for a few minutes adjust as needed. Double check in 20 minutes. Personally I set them on 80 mA.. No meter is needed. The front panel meter read bias.

After this start up, you won't need to adjust bias again for years, unless you just want to experiment. The 350s use a similar circuit. I have ran those over 2 years, almost every day, without need to adjust bias. 

Really about as painless as solid state.

Thanks for the reference, shown below.  I don't doubt that the Crimson would be a good mate for your JBL speakers!  For me, personally, a tube amp without auto-biasing is non-starter.  Tiny screwdrivers and a power-up amplifier are the not the way I roll anymore.  Cheers. 
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

ADJUSTING THE OUTPUT TUBE BIAS ON THE CRIMSON 275

The front panel incorporates a bias meter. Turn the preamp volume control all the way down while performing bias adjustments. Use a small screwdriver and adjust the bias control (located on the rear of the amplifier) for 80 mA after the unit has warmed up for about 20 minutes. The normal range to use is from 60 mA to 120 mA, and changes here will vary the damping factor of the amplifier slightly. More current increases the damping factor, whereas less current provides a softer more tube-like sound. The design center is 100 mA, and that should be your starting point if you want to experiment. Personally, I found that I loved the sound best on my speakers when I had it set for their design center of 80 mA. It will vary from speaker to speaker, and most importantly with your taste.

The meter reads the combined current for all four output tubes, and it is normal for this current to vary slightly with changes in power line voltage.

The biasing is explained in the owners manual ( can be found on d2girls thread ) A tube amp for my JBL 4367s.

A question to Jim Clark. It is not clear how the biasing function on the Crimson unit works.   I am guessing that one would not need a voltmeter for biasing, but it doesn't appear as though it has auto-biasing.  

Can you explain the biasing procedure?   Thanks. 

Actually, I am not sure why I am surprised at the lightweight transformers he is using in the amp. I still have in my possession, a Carver MCT moving coil transformer that he sold and priced at $ 149. at the time ( it might have been $ 129. ). It was better than my M.A. Cotter, my Denon, and several other mc transformers and head amps I owned ( I owned many and heard many ). I, too, sold, and owned Carver gear ( I recently sold a Yamaha B6 amp, yes the Darth Vader unit, using his design.  ). As an aside, It is my understanding Yamaha stole the design, without permission or an agreement with Carver, which is why it did was not available for very long. I should have kept it, just to have, but I was made an offer I could not refuse. I had his earlier Phase Linear gear, and always respected it and never had a problem with any of it, although some people called it Flame Linear ( pros, mostly ). I do believe Bob Carver is as brilliant as they come, and it might just be a perfect match for my modified / tweaked Lascalas. When I was " in the field ", I was sent many loaners of audio products to experience, some even before the actual release date, without exchange of money. I am tempted to contact Bob, and reintroduce myself, to get a loaner. This is how good this amplifier seems to be. Enjoy ! MrD.

I'd like to see a pic of the insides if anybody has one.  Not interested in buying one, just curious.  I owned a few Carver pieces back in the 80's.  

Very impressive, no doubt.  Thanks, Jim.

Jim,
I appreciate your feedback on this thread, and I would suggest that you encourage, if possible, audiophiles to whom you have sold the amp to chime in on the thread with their experiences with their particular systems.  I think this amp might well be outstanding, but I am still surprised that that here are no extant customer reviews of the amp.  I reckon far fewer folks have a Don Sachs KT88 tube amp, but there are many reviews of his unit on this forum.  

Absent  those reviews, I will say that you offer an excellent opportunity for folks on the fence about the worthiness of this tube amp to give it a try in their system.  Bob Carver is a genius and if this amp is found to be similar in performance to the 350 mono-block tubes amps that are much heralded for good reason, then I expect you will sell lots of them.  

Jim Clark, there is another recent thread started by d2girls, reading : " Tube Amp for JBL 4367 ". Could you post the same there, as it would be helpful. Thx, Enjoy ! MrD.

Hi Guys,
The Crimson 275 sounds almost exactly like the larger 350 watt mono-blocks. It has a strong and well controlled low end. Its detailed in the mids and highs but is smooth and never edgy. The soundstage detail is fantastic. It has nice tonal balance imho and the mid range is accurate. Female voices sound sweet but never overly thick, like in some of the vintage tube gear. It really has the best parts of tube audio without the high tube maintenance and heat output. I have sold them all over the world (Switzerland, Israel) with a 100% satisfaction guarantee. No-Restocking fee. They don’t come back. In stock. Free shipping in the USA.. Try it at home. If you don’t love it, just send it back. See my site w/ secure store or call..

Don't own one, but am waiting to hear more about the Crimson amps.

They last long because he runs the tubes cool, have read can touch when operating. Backs it up with 5 year warranty for 275 and 10 year for 350.

Well, this thread is over three month old and nobody has yet responded who owns a Crimson amp.  I note that the Crimson amp only 19 lbs and Don's amp is around 65 lbs.  Presumably the Crimson has much longer tube life.  Nobody seems to know why.  

What are some of the advantages the crimson 275 has over the Don sachs katooney?

Ozzy, 
I have a couple of thread going on this amp, but I decided instead to order Don Sachs Kootenay amp after hearing it in my system.  It does everything my Platinum McCormack does... amazing LF control, but Don's amp is vastly more holographic.  Lots of the better tube amps have this characteristic.   It is a tall order for SS amps to perform similarly. 
I am still eager to hear from someone who can comment on the sound of the Crimson in their system.   

whitestix,

If you are planning to use the Carver with the XLR inputs I have found an error in the wiring on my Raven 350's. Easily correctable, If your interested let me know.

ozzy

I'll be Interested in the findings between the 2 amps.

Tomcy6,
I did speak with Carver, but it would be more informative to hear from folks who have experience with the amp in their systems.  I will report my impressions of the amp in due course so at least we can get the ball rolling.  Jim Clark tells me that he has sold more than a dozen of them so they are out there.  Music Direct and Wally Underwood are also selling them. 

Don offers only one amp; the descriptors are synonymous.

What is the Sachs Kootenay KT88 amp? I spoke to Don about the Custom KT88.

The amp is new so you probably won't find much feedback on it.  I'd call Carver and see what they tell you.  Have them compare the sound to the 350s because there is more comment available on those.

Ozzy,
I am really keen to see how it sounds, after being away from tube amps for many years.  My Spatial Audio speakers have a 12 ohm impedance which clearly mates well with tube amps.  Thanks for the response. 

I have never heard of the Kootenay but I own the Raven 350 and it has a vintage modern sound. The 275 should sound about the same way albeit with less power.

ozzy