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.
