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Carver Crimson 275 Measurements

TriodeLuvr

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1% is not even noticeable on a scope trace, much less be anything like clipping. Here's a plot picked from a random review on the first page results at Stereophile:

View attachment 178880
source https://www.stereophile.com/content/doshi-audio-evolution-monoblock-power-amplifier-measurements

Here's another off that page:
View attachment 178881
source: https://www.stereophile.com/content...cbloc-monostereo-power-amplifier-measurements

I'm not seeing that soft clipping in either example. It goes through the roof just as sharply as any other kind of amp.
I wasn't referring to soft clipping. But you're correct, 1% is barely noticeable on the scope. The point is that hard, square clipping will occur immediately after we reach 1% in a solid state amp if power is increased, but the tube amp will exhibit considerable additional headroom. That is what creates the difference.
 
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paulbottlehead

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Total FWIW dept.: the Edcor EM04906 is not a catalog item. Further, all the Edcor parts sans end bells have purple bobbins- they look distinctly different. So the transformer in question does appear to be a custom unit. FWIW.
1638323986190.jpg

Not all Edcor iron has blue bobbins.
 

HammerSandwich

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QUESTION: Bob is it fair to say that you design amplifiers for reproducing music into dynamic loudspeaker loads, more so than focusing on reproducing sine waves into load resistors?

ANSWER: There is some truth to that. My amps can perform way above there power rating for a time, a time being several seconds.
@amirm, would you be willing to test distortion versus SPL with this amp driving a speaker? Also test with a ~50W SS amp for comparison.
 
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paulbottlehead

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What measurement do you want for this?
I had considered the possibility of a reactive load (test woofer or two way speaker) with a frequency response sweep, then taking a capture with and without the negative binding post connected to the shell of an RCA jack with a clip lead.
 

Zackthedog

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I had considered the possibility of a reactive load (test woofer or two way speaker) with a frequency response sweep, then taking a capture with and without the negative binding post connected to the shell of an RCA jack with a clip lead.
I'd be very interested to see that. Not just in fairness to the amp, but from an academic POV.
 

Thermionics

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Is that four vintage oil capacitors at the top?
Not really vintage - they are Russian mil-spec K40Y-9 paper-in-oil caps. Good enough for a MiG, good enough for an amp. ;)

(Note: they look a bit funky because they're in heat-shrink tubing as they have metal bodies - trying to avoid letting out any magic smoke)
 

Thermionics

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The green potentiometer at the top is for adjusting the bias (EFB - the LM337 is hidden underneath that mess of wires, resistors & capacitors, and ground bus slightly north of the two can caps). If I wanted to completely redo the internals, I could probably come up with a cleaner layout, but it is very quiet at idle and I'm a cheap bastard.
 
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paulbottlehead

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reactive load floating speaker -.jpg

Here's the amp hooked up to a test woofer with the speaker - terminal floating.
reactive load earthed speaker -.jpg

Here is the amp playing into the same woofer at the same level but with a clip lead connecting speaker - to the shell of an RCA jack.

So there is a difference that's not substantial and very much frequency dependent. While I can measure this here pretty easily, it inspired me to look at some tests into an actual woofer (a little 3" Hivi).

At 1% THD/40Hz, I can get about 600mV (not going to talk about power since the impedance curve is all over the place) with the speaker - floating. If I put a clip lead from speaker - to the shell of an RCA jack, that number goes up to around 720mV.

If I try this again at 1% THD/250Hz, I can get 2.9V with speaker - floating and 3V with the speaker - grounded.

These are different, but I will leave it to others to properly quantify this in ways maybe I shouldn't ;)
 

tvrgeek

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Never heard of this set. Only the Silver seven which he built to prove you could "flavor" any technology to sound like another. I heard one once and it was quite good. Tube to bipolar? Increase the grid resistor.

Bob Carver was good at pulling ideas from other areas outside of audio and applying them. Personally, I never cared for them. The "autocorrelator" came from microwave work in the DoD. The "Magnetic Amplifier" I laughed all day when I saw the schematic as it was almost identical to how we controlled out reel motors.
 

Jpahere

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Good evening all. I have been following this thread with a great deal of interest. Everyone here who has owned a Carver Crimson 275 amp (with a serial #) please raise your hand. I will wait. I do have the amp - I've owned it for 6 months now. As I write this I am listing to Sade singing "Hang On To Your Love." I am using a Schitt Freya+ preamp and amazingly I am listening to the music through Eminent Technology LFT 8b speakers which require a minimum of 75 Watts. Excuse me a moment. I have to turn this down. I can't hear myself think. That's better. To paraphrase Sienfeld, the sound is real and it is spectacular! I have no idea what Amir will find. Maybe it is a puny 15 watt per channel rip off. I don't know. I would want to put down my torches and pitchforks until I got a definite answer or heard the amp for myself. In the interest of full disclosure, I had run the bass with a SS Parasound amp. I disconnected that, increased the bias just to see of the amp could pull it off. Anyone want to buy a Parasound 23+ amp? It was designed by a man whose first name is apparently "Legendary" :)
 

Blumlein 88

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Good evening all. I have been following this thread with a great deal of interest. Everyone here who has owned a Carver Crimson 275 amp (with a serial #) please raise your hand. I will wait. I do have the amp - I've owned it for 6 months now. As I write this I am listing to Sade singing "Hang On To Your Love." I am using a Schitt Freya+ preamp and amazingly I am listening to the music through Eminent Technology LFT 8b speakers which require a minimum of 75 Watts. Excuse me a moment. I have to turn this down. I can't hear myself think. That's better. To paraphrase Sienfeld, the sound is real and it is spectacular! I have no idea what Amir will find. Maybe it is a puny 15 watt per channel rip off. I don't know. I would want to put down my torches and pitchforks until I got a definite answer or heard the amp for myself. In the interest of full disclosure, I had run the bass with a SS Parasound amp. I disconnected that, increased the bias just to see of the amp could pull it off. Anyone want to buy a Parasound 23+ amp? It was designed by a man whose first name is apparently "Legendary" :)
If a guy tells me he has this new big pickup truck and that is powerful like the big ones from Ford, Chevy or Ram, and I open the hood to find a 25 hp V-twin from John Deere powering it I don't need to own it to be skeptical and reasonably so. If they can go show me it works then fine. Amir will find out the truth of the matter soon enough.
 
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paulbottlehead

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I would also like to take measurements of the voltage appearing across C36 and C37 at startup when I get the production unit back from Amir.
 

Zackthedog

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Good evening all. I have been following this thread with a great deal of interest. Everyone here who has owned a Carver Crimson 275 amp (with a serial #) please raise your hand. I will wait. I do have the amp - I've owned it for 6 months now. As I write this I am listing to Sade singing "Hang On To Your Love." I am using a Schitt Freya+ preamp and amazingly I am listening to the music through Eminent Technology LFT 8b speakers which require a minimum of 75 Watts. Excuse me a moment. I have to turn this down. I can't hear myself think. That's better. To paraphrase Sienfeld, the sound is real and it is spectacular! I have no idea what Amir will find. Maybe it is a puny 15 watt per channel rip off. I don't know. I would want to put down my torches and pitchforks until I got a definite answer or heard the amp for myself. In the interest of full disclosure, I had run the bass with a SS Parasound amp. I disconnected that, increased the bias just to see of the amp could pull it off. Anyone want to buy a Parasound 23+ amp? It was designed by a man whose first name is apparently "Legendary" :)
I don't think anyone here will begrudge you your enjoyment of the Crimson 275. I use a pair of homebrew, 22wpc Williamson monoblocks with the "legendary" (for good reason) Peerless S-265-Q output transformers. I enjoy them tremendously, but I'm also well aware, from my own measurements, that they fall short in many respects. The fact is that honest measurements matter. For that reason alone, I wouldn't be too snarky about John Curl. He enjoys a far more robust reputation than Bob Carver.
 

Jpahere

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I don't think anyone here will begrudge you your enjoyment of the Crimson 275. I use a pair of homebrew, 22wpc Williamson monoblocks with the "legendary" (for good reason) Peerless S-265-Q output transformers. I enjoy them tremendously, but I'm also well aware, from my own measurements, that they fall short in many respects. The fact is that honest measurements matter. For that reason alone, I wouldn't be too snarky about John Curl. He enjoys a far more robust reputation than Bob Carver.
Zack, I would never besmirch John Curl, God knows I bought enough of his equipment. I just think it is funny every reference about the man starts out "the legendary John Curl." He is a much more modest gentleman than that! And I totally agree with honest measurements. If the amp is seriously less powered than advertised I will look for something else. I am not lying though when I tell you these LFT 8b's and this amp keep me up past my bedtime.
 

audioholic63

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Good evening all. I have been following this thread with a great deal of interest. Everyone here who has owned a Carver Crimson 275 amp (with a serial #) please raise your hand. I will wait. I do have the amp - I've owned it for 6 months now. As I write this I am listing to Sade singing "Hang On To Your Love." I am using a Schitt Freya+ preamp and amazingly I am listening to the music through Eminent Technology LFT 8b speakers which require a minimum of 75 Watts. Excuse me a moment. I have to turn this down. I can't hear myself think. That's better. To paraphrase Sienfeld, the sound is real and it is spectacular! I have no idea what Amir will find. Maybe it is a puny 15 watt per channel rip off. I don't know. I would want to put down my torches and pitchforks until I got a definite answer or heard the amp for myself. In the interest of full disclosure, I had run the bass with a SS Parasound amp. I disconnected that, increased the bias just to see of the amp could pull it off. Anyone want to buy a Parasound 23+ amp? It was designed by a man whose first name is apparently "Legendary" :)
So are you currently running the LFT8B just with the Crimson 275 or are you still bi-amping with the Parasound?
 

Jpahere

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This evening I ran the speakers with just the Crimson and they sounded fine. The sound is better when it is bi-amped and I have since switched it back.
 
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paulbottlehead

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I would suggest playing a 30Hz test tone at what you consider a loud level with the Carver, then your SS amp. That would make the difference very apparent.

If you listen to low demand music not very loudly and with not a lot of low bass, the differences may not be all that apparent.
 
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