Carver’s own specs: 19 lbs for a Crimson 275 rated @ 2x 75 Watts?? That’s ridiculously lightweight, for a tube amp. That puts it in the class of a console-pull EL84 amp pushing ~ 15 Watts a side. No amount of Bob Carver "magic tech" talk can make that go away from my mind. The higher-end Carver monos also weigh only 44 lbs a side and claim 350 Watts! That’s very concerningly over-light, for the tube powers involved. The Rogue Audio Atlas weighs 55 lbs, actually hits its rated 100 Watts x2, and costs roughly the same as a Crimson 275. The Rogue Apollos weigh 100 lbs per side, spec 250 Watts, and cost similar to the Carver monos. Hell, I have a pair of Heathkit W5 that EACH weigh over 20 lbs. These are 25 Watts/ch KIT amps from freaking 1959. Their manual publishes detailed power response curves under load, and they literally kick the crap out of what ASR measured for the modern-year Carver Crimson 275! They sound really sweet, too.
Perhaps the proper production models contain the appropriately sized transformers AND a magic Bob Carver gravity-cancelling device?
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I agree listening enjoyment is most important to our hobby. I’m no fan of ASR - they put listening dead last. But outright false claims by manufacturers can also damage the hobby. And I don’t see how these particular amps come close to hitting their power specifications, unless they can break the laws of physics or have a hidden plate amp under those transformer covers. I’m not a stickler for 1% THD being the "clipping" cutoff for power measurement, but it shouldn’t be pushed much more than a few %.
Sure, I’m biased - I had a Sunfire Sig II amp a while ago and hated its sound. Too many aspects of Carver, and these tube amps, set off my BS alarms. Aren’t the tube fuses on these amps even advertised as a tube HEALING feature somewhere? LOL
These amps might well sound good, but it’s looking more and more like they should have been spec’d at a much, MUCH lower power. Now where’s the value? Plenty of low power vintage amps that sound wonderful. EL84, 6L6, and EL34 tubes are hard to make sound bad.
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I used to play around with vintage tube amps. Lovely sounding amps, in the range of 20 - 35 Watts. With 90dB speakers, an honest 20 Watts is plenty to drive them quite loud for LOTS of music. It'll even sound very pleasing, too - good to the last Watt, so to speak. In an intimate setting, with a controlled playlist (lots of Krall etc) you may never want for power. The could even play dynamically compressed rock recordings very loud (and they weighed more than the Carver, btw). But it would run out of power in a hurry once you started cranking more dynamic material.
Modern push/pull amps with KT120 are SUPPOSED to give you all the power and overhead you need, at meaningfully low distortion levels, with a good dose of the tube sound if not the full boat E84/6L6/EL34 "sweetness".
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Sure that’s cool, now all Carver has to do is explain how 19 lbs of tube amp from his factory breaks the laws of physics to drive an honest 75 Watts per side 😂
It will definitely involve "magic transformers". I guess they didn't have the magic ones on hand for Carver fest 😥
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@jbhiller
😥
Thanks for that, though. Now we might expect some sort of tug of war over what constitutes acceptable bandwidth at power, THD limits, and measuring setups - and how this should all filter down to single power #. It’s perhaps interesting to look back at Heathkit W5 manual from 1959 and all the wonderful measurement curves provided right in the manual (the bandwidth looks very good for a 25 Watt rated tube amp):
To be fair my VAC amps don’t exactly measure stellar either - and I enjoy them regardless.
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@snapsc
From the manual specs section, on power:
More than 75 Watts Per Channel, both channels driven at eight ohms, from 20Hz to 20kHz with no more than 1% total harmonic distortion. Distortion decreases at lower levels.
Oh my - it spec’d the rated power at both channels driven, full musical bandwidth, and 1% THD. That doesn’t leave much room for interpretation, and it’s going to be one hell of a tall order for those little OPT’s 😬
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Honestly if I were an owner right now, a solid 60 Watts x2 would be OK with me, even at THD a point or 2 above 1%. I’d certainly be disappointed at being sold misleading/erroneous specifications, but that would be "close enough" - 60 versus 75 is still usefully powerful. 17 - 20 is another story. Hopefully we'll get more clarity soon.
I know W4S cited the PT, but I’ll be really surprised if those OPT’s push out 60 Watts x2 as recognizable music.
Anyways, my audio tech & now dealer has been Gordon Waters here in Marietta GA for many years. He’s designed speakers and restored countless vintage tube amps (including a couple of mine). I trust him implicitly. On Audiokarma he posted the following interesting analysis about the Carver 275 schematic (which to Carver’s credit was included in the manual) - no comment on the transformers, just the circuit:
I was just having a conversation with some really astute techs about the Carver 275 amp, regarding a feature I just noticed, in the schematic:
Look at resistor R53 and R44, connected to the negative speaker lead. That’s basically the same type circuit as the original Fisher 55A "Z-Matic" output-impedance adjusting circuit, just without the adjustability that Fisher provided (including the ability to turn it off, in the Fisher!). Here, it’s set to a fixed level of current feedback, reducing the damping factor. This will act to "color" the bass of most speakers- in a not-so-predictable way (each speaker has different impedance characteristics, which will interact with the network in different ways). This is ostensibly the "listening to the speaker in the room" thing that Carver was talking about, I would think. It’s funny, though, that it’s something that most experienced techs recommend REMOVING from the Fisher amps, since it’s rarely needed (unless you have very early speakers, designed for use with for amps with very low damping factors, such as 1950s JBLs, Altecs and such), and it’s rarely beneficial...
Also, more than one tech mentioned that they were struck by the myriad compensation networks needed for stability and response modification in this amp. Low-frequency shelving on the input (though switchable), HF frequency response limiting on the output of the first gain stage, LF shelving between the phase inverter and the output tubes, HF snubbing/shelving on the primaries of the output transformers, a Zobel on the output, AND a two-stage shelving network in the feedback loop itself, as well as the "output impedance modification" circuit described above. It’s rare for ANY amp to need THAT MANY different networks. Maybe two or three, tops- for example, the Eico ST70 "Hot Rod" uses three (plate-to-grid HF compensation on the phase inverter, HF snubbing/shelving on the OPT primary, and a Zobel)- but almost never SEVEN different response-modifying networks in one amp. I wonder what square wave response looks like, under normal operation, and also with each of those networks disconnected one at a time, to see exactly what each one of them is doing...
Mind you, having all those networks doesn’t necessarily mean the amp would perform badly or sound bad- but with each network added, there’s always the chance of "throwing away the baby with the bath water", in terms of sound. Every compensation network represents a compromise of some sort...
Regards,
Gordon.
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@jbhiller
Absolutely, I agree listening results come first. This is specifically about whether Carver needs to down-rate its amplifiers, not whether the amp deserves to exist. Likewise, it raises the question: do we have a problem in the high-end 2 channel amp industry right now? Do we need to look at other companies and how they’re rating amps? Maybe we’ve been too comfortable since the HT receiver "peak power" rating debacle in the 90s / 2000s - back then it was easy to say "haha, HT guys - not my Krell!". What about now?
I hate taking sides with the ASR guys because they’re measurement zealots and (mostly) outright anti-audiophile. The overall theme of that forum is listening tests come DEAD last - which to me, means their real hobby is measurements - not music.
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@jbhiller
Totally agree! Haha that reminds me several years ago - I had 400 Watts/ch Parasound JC1 monoblocks, then VAC Auricle 80 Watt KT88 monoblocks - and picked up a pair of 50 year-old 20 Watt Heathkit W4 mono amps (restored buy Gordon) on a whim. The JC1’s were GREAT amps but I’m almost embarrassed to admit how much I enjoyed those little Heathkits - they were just so sweet sounding and enjoyable. NOS Tung-Sol 5881 tubes.
Soon I learned the limits of that 20 Watts on my (then) 90 dB speakers (Tannoy Dimension TD10), but it really impressed me how amazing even simple tube amps can be.
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To be fair, the ASR measurements show it performing a lot better into 8 ohms: 60 Watts/ch sustained at 1kHz, and at less than 1% THD. The really bad numbers, where it greatly underachieves its rated power (< 20 Watts/ch), are into 4 ohms. Without multiple taps this amp can only be optimized for one load, and it looks like it’s 8 ohms.
It did better than I expected at 8 ohms, but then 60 is still clearly under rated power, and it blew a fuse on top of that. And power bandwidth is clearly a big shortcoming here, probably much more than with other tube amps.
It’s probably not filling any necessary market slot with this performance.
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Is it 60W sustained if that blew the fuse?
Haha, good point. I'm sure putting in a larger fuse value might allow Bob's circuit magic to be unleashed. Of course you have to insert the fuse JUST right, because as we all know now, the grounding in this amp is very complex 😂
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My buddy has spacial turbos M3 and drives them with 400 watts oer channel of class D amps, he borrowed my crimson 275 and said he had to keep the volume at 1/4 which was less than the class D and indicated the sound was better.Tube amplifiers in general even with really low watts per channel seem to drive speakers easier than solid state rated at the same watts per channel. Maybe someone could shed some light on why (higher current)
Don't confuse power for gain, or volume position. Tube amps often have a relatively high sensitivity & gain. The Carver 275 is spec'd at 29dB gain. That's a lot for only 75 Watts / ch! It's a LOT LOT of gain for a 15 Watts / ch amp! Many tube amps lead with a V1 12ax7, and a lot of gain can come from that.
For comparison: the Parasound JC5 is also spec'd at that same 29dB gain - but with 400 Watts versus the Carver's 15? 60? The problem (for the Carver) is that the JC5 has a lot more "runway" before it runs out of juice.
High gain in an amp is good when there's a LOT of power on hand to be tapped, or when the use case is for sources with low output levels (e.g. vinyl with a very low output cartridge < 0.2mV, or passive preamps, etc). In the modern era, a low power high gain tube amp doesn't make as much sense IMO.
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The Carver 350s are built like tanks but cost $9,500 for a reason. This Carver 275 is a nice entry level audiophile product (akin to solid state Rotel 1500 series units).
I’m buying the Mac: tried and true 100wpc @8ohms/160 @ 4---with a true .005 distortion level. 4 cozy USA tubes that glow green and create that nice warm sound. $4,500.00--done and done.
The focus has been squarely on the Crimson 275, deservedly so, but does anyone really trust that Carver Raven 350 now? It’s only 44 lbs per side (most certainly NOT built like a tank) and rated at 350 tube Watts per channel into 8 ohms; 400 per ch into 4 ohms! That power rating represents the KT120 tubes running at around their limit (which is FAR from reality on the 275). That’s maybe even more optimistic a power rating than the 275! At 44 lbs there also has to be a lot of air under those huge transformer covers. The most credible spec on its sheet is its (near) $10K price.
Compare to the Rogue Audio Apollos which are 100 lbs per side and rated (quite likely an honest) 250 Watt /ch. Or the M180, rated 180 Watt / ch, 55 lbs a side, and about $3K less than the Raven 350. I would bet the M180 easily out-powers the 350 on a bench.
Anyways, you made a good choice going for Mac over Carver!
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