I own the Carver Raven 350 amps and I'm very pleased.
I've enjoyed tube amplifiers from Marantz, Dynaco, MFA, and Bob Carver as well as linear and switching solid state amplifiers in between. I experienced noticeable output tube degradation within one to three years as well as typical bias adjustments with all the tube amps except the Carvers.
I replaced one output tube due to my own clumsiness. The new tube measured very close to the rest of the original set that have been in service for the past five years. After the replacement the group bias was exactly the same. Case mounted tube sockets and point to point wiring.
This review will give some historical background regarding the collaborative design and development.
Thanks for the insight, it is valuable. I have had a ton of tube gear, including a HK Citation C-II and C-V, fully restored, and lots of other tube amps and I parted with them for solid state amplication. I might revisit my affair with a tube amp with Carver's new offering. It looks to be a robust and reliable unit at a very fair price.
I have pretty much abandoned tube amps for the obvious reasons, but am enthralled with with Don Sachs' 6SN7-based tube preamp... I think a lot of the magic of tube sound is captured in a preamp. I went through a lot of KT88's, etc. with earlier tube amps-- a pricey proposition, and the biasing was a PITA. Evidently the amp is not auto-biasing, but Carver's literature indicates that once you set the bias, it need not be re-biased for a long time.
I am going to audition Don Sachs Kootenai KT88 amp soon so I will see if I can abide with a tube amp again. I am rather dubious, but frankly have never heard a tube amp with more than 60 wpc and my Spatial Audio speakers, while rated at 94 db efficient (or is it sensitive?), did not at all perform well with my wonderful Dennis Had ~16 wpc SET amp. It provided no "oomph" to the music. It is somewhat similar with my Pass Labs F5 amp with 25 wpc of Class A power... it just doesn't have the same sonic presence as does my McCormack amp, not even close.
So, if the potent Crimson 275 amp will energize my speakers in the same way the McCormack does.... and
add more liquidity to the music, then yeah, I am going to acquire one. I am 65 years old and have had two boatloads of audio gear in my life, but I have never owned a Carver product. Maybe now is the time...
The tubes in the Crimson 275 are warranted for five years. Our competitors give three months. Prima Luna, an excellent product, gives six months. The tube checker is built into the amplifier. You can check your neighbors' tubes at full operating parameters. We've given out between three and 10 tubes in the last 10 years depending on who you speak to. On this model tube life would be about 20 years. It's even greater on our more expensive amplifiers (and their extended warranties reflect this) but we run the KT 120s a bit harder in order to come up with 90 W per channel which every 275 is capable of. We have no service department because we have no failures. The 275, like all of our amplifiers, repairs defective tubes if the malady, the most common, is caused by impurities. We vaporize the impurity, sacrifice a dedicated fuse, and you're back in business.
Frank Malitz CEO
The Bob Carver company
Thank you for the information. I am not sure that I need to check my "neighbor's tubes", but that is an intriguing idea. It is evident that the amp runs in such a fashion to ensure long life to its tubes, which is are major factor in my decision to buy one.
I have never heard of a process to "repair" defective tubes. If you have such a process, I have about 60 rare NOS tubes that would be happy to see renovated to their former performance if you can do that. I am keen to hear some reports of folks that are using the 275 amp in their system.
Like most tube amps, higher impedance speakers are better matched to Don's amp. If your speakers dip below, let's say, 4 ohms, then I think it would not be the best match. With my 12 ohm Spatial Audio speakers, the bass is reproduced extremely well, pretty much as well as with my 100 wpc McCormack amp. To my mind, that is a huge accomplishment because I have never experienced such low end response in a tube amp as I have with Don's amp.
The question to ponder is whether or not your Spatial Audio Hologram M4 Triode Master speakers need an amp with high current output and control that SS offers. Like your DNA-0.5. If they do, the Carver will certainly fall short. I tried driving my restored, very current hungry German Physiks Borderland MK1 with my Carver VTA180M Cherry monoblocks, and it was dull and lifeless. I took a shot and bought a McCormack DNA 1.0 with rev B upgrades and the GP's came alive. Was so happy with the synergy that I sent the amp to Steve for a full upgrade including the Plitron transformer. The Cherry's went back to my vinyl rig. I'm thinking the best attribute about the Cherry's driving my Legacy Focus SE's was that they were dead quiet and run super cool. Carver lifts the grounds by using only a two prong plug. And although the focus SE's are very sensitive, as far as the mid-bass and low end bass is concerned, the Cherry's "just run out of iron" and the mid range is somewhat smeared and lacks detail. The highs are just OK. Now that's MY system. YMMV. Well the itch came back, and decided to sell the Cherry's, and they will be replaced with a Wells Audio Innamorata. My front end remains tube though, and its going to be an interesting experiment driving the Wells with a Dehavilland UV3 and Fosgate Signature phono stage front end. When using the Carvers, of course go by what your ears say, and not the published specs, because Carver tends to always "exaggerate" his performance specs.
The M4 Turbo S speakers which I first had had an impedance of 4 ohms, which of course was a poor match for my flea-watt Dennis Had amp. However, with the M4 Triode Masters, Clayton has modified the speaker to present a 12 ohm load, much more favorable to a tube amp.
I have Don Sachs' tube preamp and i got a chance to audition his Kootenay 120 tube amp last week in my system, which has 65 wpc. I, and the audiophile who bought Don's amp for us to hear, both quickly and decisively concluded that we greatly preferred the SQ of the speakers with Don's tube amp compared to my very fine SS amp. (As an aside, he went home and ordered a pair of M3TM to replace his $8500 "box" speakers, feeling that the OB speakers had an openness and expansive soundstage to which his conventional speakers could not compare.)
With the tube amp, the music was presented with luscious liquidity and, most surprising to me, a potent grasp of the low response. The instruments were palpable in the expansive soundstage. I was pretty much blown away as I have never heard a tube amp with such authority and extension and such a natural presentation of the music. I conclude that this performance is a function of the 12 ohm impedance of the Triode Masters -- a much more compatible load for any amp, either SS or a tube. YMMV with different speakers.
Don's amp is sweetly compatible with my speakers, but I am intrigued with the Carver for its long tube life and its affordable cost. I frankly doubt it would sound as fine as the Kootenay amp, but I would sure like to hear one for comparison purposes.
I heard the Immorata auditioned by Jeff Wells in his listening room some years back, and couple of other times at audio shows, and came away with the impression that his amp provided a glimpse of the finest amplification that one could ever experience, pretty much regardless of price. I wonder how my Platinum-upgraded DNA-05 would compare to the Immorata?
Thanks for post.
Excellent point. I have recently become aware of the implications of speakers' impedance, which can be a different aspect of performance than simply considering speakers' sensitivity/efficiency (I can never remember the difference between the two). To wit, my pal has a Don Sachs KT88 tube amp driving 90 db efficient speakers, but the speakers became distorted at maybe 80 db... just crapped out. Well, it turns out the speakers were nominally 4 ohm speakers that dipped to 2.8 ohms and the amp simply ran out of gas.
Well, we played the same tube amp with my 12-ohm Spatial Audio speakers and they were simply glorious, far far more musical in all respects, including LF extension, than my Platinum-upgraded 100 wpc McCormack DNA .05 ss amp, which I think it is brilliant amp. By the way, my pal who brought the Don Sachs amp to me to audition ended up purchasing the Spatial Audio M3 Triode Master speakers for his system. The tube amp and the Spatial Audio speakers are a wonderful match, he informs me.
Again, the point to understand is that that speaker impedance compatibility is a fact to be recognized, particularly if one is considering a tube amp for one's system. Correct me if I am wrong, but it seems that most ss amps are more compatible with low impedance speaker loads while tube amps are more compatible with higher impedance speakers loads.
Correct. Tube amps primarily work best with speakers that have a higher sensitivity - in addition to a flat impedance curve. Many speakers have dips and spikes in the impedance curve at various frequencies that are not mentioned in the specs. The marketing material may just say that the speakers are a ’nominal’ 6 ohm impedance. But, that could be a median average. It could be misleading when trying to match an amp with speakers on paper vs auditioning.
I know this is an old post but it’s interesting you mentioned tube amps works best with speakers with flat impedance curve. I was told that electrostatics like Martin Logan are best paired with a tube. However these speakers have very volatile impedence and could often drop very low, as I heard. Is there any truth to this? Thanks! I’m trying to decide whether to get my MLs a tube amp, but don’t wanna spending the money if it’s meaningless.
@angelgz2 The best place for your amp question would be at the Martin Logan owners forum. Even with their feedback, I still would recommend auditioning before purchasing.
When I had e-stats years ago, I drove them with a 300w/ch SS amp - that double-downed. The speakers sounded pretty good - even with a dip down to 2ohms. I wanted to try tubes - so I purchased a pricey pair of triode push/pull monoblocks. With these monoblocks, the e-stats sounded slightly worse than coming from an empty Campbell’s soup can. I tried a pair of Speltz Autoformers, no improvement.
At an audio show, I visited a room by Roger Sanders Sound Systems. His 10e e-stats were driven by his Magtech amps with room correction. The sound was absolutely stunning. Far better than any other e-stat (and many other speakers) that I’ve heard. But, having owned e-stats in the past, the extremely narrow sweet spot was a deal-breaker. If you leave the listening chair, they just don’t sound good off-axis.
@steakster thank you for the detailed feedback! You may just have saved me $4,500 going for that Mcintosh 275.
@whitestix yes I would think so, but despite this logic, I’ve heard from many places, including the ML owners forum that some people swear by tubes with ML. In fact, some older models, it actually says in the manual that they are best driven by “pure class A tubes”. I have had a tube amp before I owned any MLs and I tried it with a pair of Dynaudio Contours and it sounded horrible. I have since been reluctant to go tube again.
Cheers, happy holidays!
Well, I stand corrected on this compatibility issue. These days, everything I seem to know is wrong. I have a pal who has pretty large Tyler Acoustic's speakers that are nominally 4 ohms, but have frequency dips to under 2 ohms and he could not drive the speakers past 80 db with a 65 wpc Don Sachs KT88-based tube amp without congestion. However, in my system with 12 ohm Spatial Audio M4 Triode Master speakers, his amp was fantastic, truly, just brilliant. He bought a pair of Spatial Audio M3 Triode Master's and the amp is of course astonishing. The variable between the speakers is the impedance difference, as far as I can tell. Perhaps there are other variables. Mark
Well I own the Carver Raven 350 mono blocks. And I used these amps with the new Bob Carver Amazing Line Source speakers. The amps got very hot and the amp meter was swinging very hard to the right, even at lower "rock" levels.
When I switched speakers (Focal Sopra 2) the amps now run very cool and the meter hardly moves.
Hard to believe such a mismatch in impedance with 2 current products from the same company.
@ozzy . Back in the 80's I went to audition the Carver Amazing loudspeakers which were heavily promoted. The salon had a carver system w/ a preamp with holographic imaging. Long story short...it was awful. My son and I were both shocked that a high end stereo store would play something so awful and talk about how good it sounded. Maybe the speakers were good...I don't know. But whenever I think of Carver, I remember the holographic imaging and how bad it sounded. Still I d love to hear the 275 in my system
My cashy pal during my college years got the Phase Linear amp and preamp and pretty much blew us plebes away in the SPL of the system with RTR speakers. Actually, he still has the amp and preamp 40 years later.
There are rave reviews from the owners of the 350 mono's, but not yet one from an owner of the Crimson 275. I dashed my order for the Crimson amp and ordered a Don Sachs KT88 amp, which I have heard in my system and it's simply glorious.
I hope an owner of the Crimson amp catches this thread and informs us his impressions of the amp.
I own 2 of the 275s. I like them, but I'm a huge fan of Bob's gear. I'm still breaking them in, rolling all kinds of tubes but haven't decided on a combination at this point what with more tubes arriving and all. I can tell you they rock! In September right after I finished the build I was able to run them side-by-side with my EAR Yoshino V20 and they acquitted themselves quite well. I'll try and write a review as time permits.
I was lucky to obtain a Mcintosh MC 275 tube amp at ridiculous price. I will test it with the MLs and let you know how it goes. Meanwhile, I found the following explanation from another user which I think really helped me understand why MLs benefit from Tube amps:
"Damping factor and amplifier output impedance are inversely related. Damping factor, as usually defined based on an assumed 8 ohm speaker load, equals output impedance divided into 8 ohms. To the extent that the speaker’s impedance varies with frequency, that output impedance will affect tonal balance, by interacting with the speaker’s impedance vs. frequency variation.
Many electrostatic speakers, for instance, have high impedance at low frequencies, which descend to low values at high frequencies. A solid state amp, having a high damping factor and negligibly small output impedance, will produce LESS bass and MORE treble into that kind of speaker, relative to a tube amp. The tube amp, having a relatively low damping factor/high output impedance, will produce MORE bass and LESS treble into that kind of speaker."
In essence, the Electrostats seem to be the opposite of a normal drive speaker. My understanding is that normal speaker drives have higher impedance as frequencies increase. A solid state that's designed to handle the higher impedance loads at higher frequencies could not "figure out" what to do when the opposite happens. Hence the tube amp comes into rescue.
I'm a bit late here, but we voice the 275 to sound identical to the 350s which sound very much like our top-of-the-line silver seven 900s. Using Bob's transfer function testing, we can make all the amplifiers sound identical. They are all based on the silver seven sound which is based on Bob's own listening preferences combined with BBC research and human physiology which Bob was a deep background in. Once hooked to a loudspeaker though, the differences in the amplifier models are somewhat more audible, but it's subtle.
With a waiting list, since day one, I've not appropriated any units for review. Why would I? We're selling them faster than we can make them and people are yelling at me because of the waiting time. I can tell you this: virtually all of our dealers guarantee satisfaction with a money back promise yet we've not had a single unit returned out of the hundreds we've sold since its introduction only a few months ago. We've also had no defectives, but that's true of every model. The cherry mono amplifiers referred to above were not manufactured by my company.
Frank Malitz CEO
The Bob Carver Company
Hello everyone, I have been the happy owner of a Crimson 275 since Dec. 24, 2018. It is my first tube amp, so I can't compare it to any others; however, I can say that its sound is far superior to my NAD C 368 (I know apples and oranges, but it's the only kit I have for comparison). It generates a lot more current and I have to keep the volume level much lower than I do with the NAD. I also get a fuller, richer sound with the Carver.
Setup was simple. It was already properly biased out of the box. One of the fuses blew about a week ago, but extra fuses are included and biasing was super simple. All I needed was a flat head screwdriver.
BTW, I didn't buy my unit from Jim Clark but his videos convinced me to take the plunge. I was leaning heavily toward a Prima Luna Prologue Premium integrated amp because of my lack of experience with tube equipment. Ultimately, I opted to take advantage of the special pricing for the Crimson 275 and own an amp designed by an audiophile icon. The 5-year warranty on the tubes was also a contributing factor.
I too have been surprised by the lack of buzz about this product. I was hoping to read the opinion of someone who has a frame of reference with other tube amps. Nevertheless, I am a happy.
One last thing, I've been using the NAD as a preamp until I purchase a proper preamp dedicated for use with the Crimson 275.
A friend whose judgment I trust has recommended a pair of the 350s for my Magnepan 20.7s and I'm very tempted but I do wish there was something between the price level of the 275 stereo and 350 monos. It would be great if the 275 stereo could be converted to a monoblock for example. I just don't think the 350 monos are in the cards dollar wise for me. I may at some point seek out a used pair.