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Carver Crimson 275 Measurements

Rottmannash

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Too bad that Carver amp is such a low-power weenie - if it were a true, robust 75WPC tube amp like this VTA-120, you could fire it up and the heat from those big KT120's would help dry out your house.

is that 363 degrees F???
 

Larry B. Larabee

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Poll: What happens first:
1. The 275 factory version gets tested.
2. Elon Musk issues the fully autonomous driver software.
 

L0rdGwyn

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The IEC safety earth is left floating, and the mains primary is ground referenced via a 4.7Meg resistor? I'm not familiar with this practice.
 

DSJR

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My professional experience includes warranty service for Crown, Revox, B&O, Dynaco, Phase Linear, Sansui, Teac, Akai, and many other well-regarded brands. That was in the '70s and '80s. My listening experiences then and since expand that at least three-fold, adding names like Levinson, GAS, NAD, SAE, etc. You can believe that I not only know what solid-state sounds like, but that my permanent switch to vacuum tube amplification some 25 years later was not an arbitrary decision.

As a measurement person, I certainly agree that numerical comparisons between these two genres are worthless. But I also believe the audio industry has produced an overwhelming amount of solid-state equipment for all the wrong reasons. Solid-state gear is cheaper to produce and easier to market to a consumer populace eager to believe it will bring the best of modern sonic technology into their living room. Much of it fails miserably in that regard, but it continues to find favor for reasons of cost, size, power consumption, and above all, profitability. Those of us who believe in the audible superiority of vacuum tube gear are not fooled.

I know this is a contentious subject, and I don't wish to debate it with the masses. Nevertheless, I stand by what I've said here, and I hope each of you who has not enjoyed the privilege of hearing a musical performance reproduced at its finest will someday find the time to audition a well-designed system utilizing only tubes. I do this every day, and like I said earlier, I'll never go back.

Jack
I find the total opposite - amazing how we humans can differ... To me, good solid state doesn't 'sound' at all, but all the valve gear I've owned and used over the years seems to add or change something and often you can't hear recording and production differences so well (I have to say the incredibly 'flavoured' tones of some top ARC preamps still allowed production differences through, just through a rosy tinted window and the E.A.R amps I knew were an artform as the designer could 'design' to spec I remember).

No probs, just fascinating to me...
 

DonH56

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Tube amplifier "soft saturation" has been understood and well-documented in numerous papers and textbooks for decades. Since most everything is SS these days tubes are no longer taught in school, at least not the universities around here. I was told by one of my profs that my class was the last to use a text that actually went through tube theory and practice (ca. 1980'ish). But as @SIY noted, blocking is a real problem that is also well-known but the design must account for it, and of course issues with transformers and such. Tube amps are not immune to nasty clipping behavior.

I have had good tube systems (ARC, Counterpoint, etc.) and SS but my current system is all SS and I have no desire to return to tubes. Not that the sound is all that different, but SS is less hassle and lower in power and weight. My back likes it.

IME/IMO - Don
 

SIY

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Tube amplifier "soft saturation" has been understood and well-documented in numerous papers and textbooks for decades.
The clipping waveforms of conventional tube amps (e.g., Dynaco, Marantz, Eico...) look the same as any other clipping, and I've seen a LOT of them. The only "soft limiting" I've ever seen is in some single ended preamp circuits. The infamous Hamm paper also only showed this in the same situation.
 

DonH56

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The clipping waveforms of conventional tube amps (e.g., Dynaco, Marantz, Eico...) look the same as any other clipping, and I've seen a LOT of them. The only "soft limiting" I've ever seen is in some single ended preamp circuits. The infamous Hamm paper also only showed this in the same situation.
Yah, that's why I put "soft saturation" in quotes. IME, which in no way matches yours for this sort of thing, the transition to clipping is largely a function of feedback and SS and tube designs are essentially the same for most any reasonable design. There may be a difference in a narrow transition region, but if you (not you-you, any you) just think about the waveform when clipped, it does not matter what device is in the circuit -- a clipped waveform is, well, clipped!

Many years ago I looked at some guitar amps and found that the "soft clipping" sound was mostly a consequence of single-ended, low-feedback design (more 2HD) and the output transformer (rolling off highs and lows). A low-biased quasi-open-loop JFET before a SS stage did pretty much the same thing.
 

L0rdGwyn

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The clipping waveforms of conventional tube amps (e.g., Dynaco, Marantz, Eico...) look the same as any other clipping, and I've seen a LOT of them. The only "soft limiting" I've ever seen is in some single ended preamp circuits. The infamous Hamm paper also only showed this in the same situation.

I see soft clipping in all of my single-ended power amplifier circuits. Example below - this is a parallel 5687 > interstage transformer > type 45 headphone amplifier. There is some additional power output here as A2 grid drive is happening - 2.1W into a 300ohm dummy load from the 45 with the grid being driven +26V positive. Pushing further, the flattening of the waveform peak worsens but maintains the "soft" rounded edges. I see the same pattern in other circuits when reading a 0V grid.

SDS00038.png
 

anmpr1

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I have had good tube systems (ARC, Counterpoint, etc.) ...
One wonders just how much of what is offered is 'market demand' driven, and how much deviation is allowed from a manufacturer's attempt to offer a 'wide range' of product, simply to pad the portfolio and satisfy everyone?

Few major manufacturers have existed in both camps, successfully. At least long term. McIntosh is probably the best example, having produced both tube and SS gear for as long as anyone can remember. In a way I am surprised that ARC has lasted as long as they have; they appear to be successful. They've carved out a niche, and mostly stuck to it.

AT one time ARC was seriously thinking about getting out of the tube business. This was evidently the plan in the late '70s, as witnessed their 'analog module' push, which was supposed to be a 'new' method of circuitry, combining the 'best of both worlds'. I don't know if anyone ever dissected one of ARC's 'modules', but most people who cared about it figured it was just a potted opamp, or FET, or something. Anyhow, the market balked (as I recall, 'influencer' Harry Pearson choked on one of them, and that was that). The company soon went back to tubes, more or less exclusively.

Counterpoint made a huge (and almost successful) push into SS/hybrid designs. One problem they had, from my perspective (FWIW), is that they started to make every kind of device at every price point they could think of, including delving into the then nascent digitial technology, at a time when the economy was not conducive to such a huge business expansion.

I know their preamps from the late '70s are still user serviceable, however the MOSFET gear is likely less so, and maybe not at all. One enterprising group attempts to keep them alive, offering 'drop in' transistor replacement circuits for key components not now available. Whether a Counterpoint owner would really want that is a question I can't answer. For a while, Michael Elliot (the designer of a lot of their gear), offered upgrades, but he left that scene years ago. As far as I know, Elliot pretty much dropped completely out of consumer hi-fi. I understand Conrad-Johnson bought the Counterpoint trademark, but never did anything with it.
 

SIY

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I see soft clipping in all of my single-ended power amplifier circuits. Example below - this is a parallel 5687 > interstage transformer > type 45 headphone amplifier. There is some additional power output here as A2 grid drive is happening - 2.1W into a 300ohm dummy load from the 45 with the grid being driven +26V positive. Pushing further, the flattening of the waveform peak worsens but maintains the "soft" rounded edges. I see the same pattern in other circuits when reading a 0V grid.

View attachment 179172
But that's because of topology, not because of tubes. You see the same thing with solid state using that topology.
 

SIY

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Many years ago I looked at some guitar amps and found that the "soft clipping" sound was mostly a consequence of single-ended, low-feedback design (more 2HD) and the output transformer (rolling off highs and lows). A low-biased quasi-open-loop JFET before a SS stage did pretty much the same thing.
Exactly. Nothing to do with tubes, everything to do with topology.
 
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