Carver Crimson 275 Review (Tube Amp)

[paulbottlehead]

He sure changed his tune from the 5th of December:

"My point is this- If those poor performing amplifiers are owned by the original purchaser and bought from Jim Clark Stereo or another authorized Bob Carver dealer, they have a 5 year warranty.. Call your dealer. They will call the factory rep.. Carver will stand behind the product 100% of the time I can assure you.. Issues are so rare they don't actually have a service department."

https://www.audiosciencereview.com/.../carver-crimson-275-measurements.29271/page-6

 

[Larry B. Larabee]

Amir should have listened to it.

 

[JDS]

This is a review and detailed measurements of the Carver Crimson 275 tube stereo power amplifier. It was purchased new by member @paulbottlehead and given to me for testing. It costs US $2750.
View attachment 179227
I really like the way the amplifier looks. The burgundy color is attractive as is the handle. On the latter, the unit is very light though so the handle while handy, is not necessary to lift the thing. Back panel shows high quality connectors:
View attachment 179230

The tubes, four Tun-sol KT120, pair of 12AT7W and 12AX7 can in their original boxes for the owner installation. Went to open one of the small tube boxes but found nothing in it! Worried, I looked around and it had come out of its box and was just floating in the larger box that they all came in.

Prior to installation of tubes I had something to investigate: there was clearly something loose in there, rattling around. So I took the back panel off to find a metal screw rolling around in there:

View attachment 179235

Not sure where it was supposed to go. There is a hole for something above the second fuse from the bottom but I think that would for a nut.

I did not like lack of safety (earth) ground from the IEC terminal:
View attachment 179238

Instead, there is some kind of local, star grounding referenced to neutral using a resistor. That naturally won't work for safety purposes. With that power supply board mounted vertically with voltages as high as 300+ volts, I sure as heck would want this metal case grounded. I don't care what audio/electrical problem they were trying to solve there. I want a safe product first and foremost. Naturally there is no safety/regulatory certification which I expect a company with the name "Carver" to be able to afford.

I got a kick out of the beefy speaker terminals but ultra-thin wires leading to it! Yes, the lengths are short and at this wattage is probably fine but from "optics" point of view, you would want to use something better than hair thin wiring (see gray and red wires).

I was sad to see the VU meter glued to the case:

View attachment 179239

I realize welding a couple of threaded stand-offs to the case costs money but at this price, I expect such. The meter is not backlit which was another disappointment. But was useful for checking bias which was right at the spec at 100 milliamps.

So nice looks but under the skin, a number of concerns.

Carver Crimson 275 Measurements
I usually let amplifiers warm up some and watch their behavior and also let things stabilize before measurements. Manual states that bias can be checked after 20 minutes so I let it run for that long and a bit more:
View attachment 179241

Note that the vertical scale is only 3 dB so don't be alarmed by the variations. Generally speaking, unit is table after a couple of minutes of warm up. But it is fascinating to see performance gradually get worse as it kept warming up (again, at micro level).

So next comes our usual dashboard. My Audio Precision analyzer by default has floating (non-earth connected) RCA terminals. But I had to override that by grounding it as I observed oscillations (frequent occurrence with some amplifiers). No other attempt at grounding made a difference in power supply/mains hum:


View attachment 179242

The power supply noise really dirties up the FFT spectrum but looking past that, we see that the low SINAD (sum of noise and distortion) is dominated by distortion. Unlike the common reputation for tubes, distortion is third harmonic for the most part, not second. Naturally the high level of distortion places the 275 very low in our scale, second only to one other amp ever tested:

View attachment 179243

Company spec is quite good for noise level relative to full power. I could not get that without a-weighting:

View attachment 179244

But applying the a-weighting filter and with it, getting rid of power supply noise, we do essentially get there:

View attachment 179245

Crosstalk was poor:
View attachment 179246

Frequency response has an odd shape and good bit of loss at high frequencies with 4 ohm load:
View attachment 179248

Output impedance is high enough that is combining with the load to change the high frequency roll off. Things get better as such with an 8 ohm load:

View attachment 179247

There is an RC filter on the speaker terminals. Wonder if that is what is providing the roll off.

Using 32 tones to simulate "music" we see a high level of "grass" which would obscure any low level detail:

View attachment 179249

Notice how the worse performance is in low frequencies.

There has been controversy regarding ability of the 275 to produce its rated power of 75 watts so let's start with 4 ohm load as I usually do:
View attachment 179250

The amplifier produced 29 watts after which it blew its 3 amp mains fuse. Fortunately two spares were provided, allowing me to continue testing. Company specs distortion at "less than 1%" so let's see power at that rating:
View attachment 179251

Very dramatic difference between 1 or 2 second power (used for left side) vs short bursts. There is clearly a capacity problem to produce sustained power. Note that this is at 1 kHz as is industry convention. Note that allowing just 1% THD reduces the power even more than what I allowed in my power sweep.

I was surprised to not see selectable output impedance for 8 ohm load so proceed with the test as is:

View attachment 179252

We blew the second fuse but now power is much more healthy at 60 watts.

Hoping to not blow the last fuse, I kept the max power level lower as I changed frequencies:

View attachment 179254

Performance was "reasonable" (for at tube) but once we got down to 20 Hz, it became super erratic and blew the third fuse. It produced only 14 wats which is well short of 30 watts it produced at higher frequencies. I would have wanted to test at more frequencies but it was past midnight and I did not feel like hunting around to find my own replacement fuses.

Conclusions
As a Carver owner of 40 years (solid state), I have a soft spot for the designer. Alas, while I like some things about this amp like the nice looking paint, I am very disappointed in the QC and construction of the unit with respect to safety. Loose screws and glued meters should not be part of a nears $3,000 amplifier. Measured performance is awful of course and one would expect that for many audiophile tube amps. But having third harmonic be dominant blows away the story of why that is audibly a good thing. Clearly the specifications of the amplifier is incorrect for 4 ohm load (company even allows usage for 2 ohm loads!). And low frequency behavior is very poor.

Unless you are going to buy the Carver Crimson 275 to just look at it, I can't recommend it for many reasons stated above. I expect more from the man, the legend....

P.S. It was nice to take a break from drying up our flooded home and get back to some "normalcy" with testing this amp. It cheered me up to be "working" again and doing what I enjoy.

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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Like you, I'm a fan of a lot of things Bob Carver did in years past: the Amazing loudspeakers, the innovative power supplies in the tiny cube amps, and maybe most of all when he humiliated the subjectivists at Stereophile by using the null test to prove he had screwed up the sound of his own solid state amp to make it indistinguishable from the tube amp they preferred. The late Pete Aczel kinda worshipped him.

So I wanted to believe Carver had figured out something new when these tube amps came out with his name on them. I guess not.

 

[Joe Smith]

What an embarrassment to the Carver name! I feel so much better about my low-cost, high-value purchases.

 

[Martin]

I wonder if one of these will output 75 watts?

Martin

 

[fordiebianco]

I am confused on the AC at the inlet also, 3 prong with no ground.

The Hot feeds a switch and the Neutral feeds a fuse???

I am from Canada, CSA will not allow a fused neutral, I am sure UL is the same.

This design is for CE 240Vac/50hz, but the label on the outside indicates 50/60Hz,

and am sure it was tested on 120Vac/60Hz.

Is this a Chinese knockoff?

Ohms

My chinese knockoffs are much, much better soldered and engineered than this.

 

[beefkabob]

Anybody wanna buy my Carver a-500x?
Actually, anybody driving from northern California up to Amir's neck of the woods, where he can test it? I'm not a fan of the likely shipping cost. Maybe I can open it and remove a metal weight?
See if that old solid state carver work is any good.

 

[jhaider]

Sorry - my point was implied in logical context.
Class action law suits tend to profit the legal professional more than the individual on a pro rata basis.

So you concede the prime facie elements of a product liability suit likely exist here but hate corporate accountability and begrudge the factfinders a living. At least it’s a consistent position, I guess.

 

[traderitch]

I have listened to the 275 at several audio shows. I thought the ones I heard sounded decent. My experience only proves to me how easy it is to deceive oneself. I would not use one if it was given to me... I would sell it however... same as I sold all my high dollar interconnects and power cords.

I still have a few pieces of audiophila in my setup. I like them but I've never directly compared them to other components.

Martin

Martin,

I appreciate your honest response.

I am not sure how the pleasant 'sound' of an amplifier can change once listened to and then measured.

Discussions (threads) of esoteric cables are often shut down on audio sites for a reason.

 

[AudioTodd]

Amir should have listened to it.

To what purpose and under what conditions and with what speakers? How would this be relevant to the rest of us and our varying setups?

Being the owner of a 7-8 watt SET 300B amp that I quite enjoy on 91dB @ 2.83v @ 1 meter speakers at the reasonable levels I prefer, I can certainly see how owners can enjoy and even love these amps!

If they sound good to you and you get your value out of them, these measurements and any listening impressions from Amir are IRRELEVANT.

Added: I have every permutation of amp type and operating class, from Class A BJT, Pentode, Class A PP triode, etc. to AHB2s and purifi-based Class D - all over the board.

 

[respice finem]

You could cover the cost by selling those expensive output tubes and putting some obscure, never-used-anymore type in their places and just run the heaters!

Or just place a micro LED inside as a "placebo", saves electricity Or behind/below, because of the vacuum inside.
/edit: Those "fakes" are even commercially available LOL https://www.google.com/search?q=fau...eSAQYwLjIxLjGYAQCgAQHIAQjAAQE&sclient=gws-wiz

 

[mhardy6647]

Need to add Roadkill Panther!

perhaps we could repurpose this?

I'm not much with photo editing, but -- you get the idea

 

[Walter]

No, and certification is an expensive process perfomed by third parties. That aside, no company selling products like this should be without it. One lawsuit, and they're done.

Burn down one measly apartment building and suddenly you're out of business.

 

[solderdude]

There is an RC filter on the speaker terminals. Wonder if that is what is providing the roll off.

It's called a Boucherot filter (or Zobel) and ensures the amplifier always 'sees' a load (probably 4.7 or 10 ohm) at > 20kHz frequencies.
It ensures stable operation with and without a load.
This should not affect the roll-off. The transformers and amp circuit will be responsible for this.

 

[Zackthedog]

Like you, I'm a fan of a lot of things Bob Carver did in years past: the Amazing loudspeakers, the innovative power supplies in the tiny cube amps, and maybe most of all when he humiliated the subjectivists at Stereophile by using the null test to prove he had screwed up the sound of his own solid state amp to make it indistinguishable from the tube amp they preferred. The late Pete Aczel kinda worshipped him.

So I wanted to believe Carver had figured out something new when these tube amps came out with his name on them. I guess not.

What's unfortunate is...he did! I mean, there's nothing actually new in the circuit, but the combination of light weight, cool-running tube, adequate continuous power and decent peak power capability is not a bad idea at all. Too bad it was marketed the way it was. Pictures of Bob "winding a test transformer" when he's clearly doing no such thing; magical terms like "listens to your room"; extravagant power claims etc. etc.

Contrast this sort of hocus-pocus with the Fisher 80-AZ user manual:

http://www.fisherconsoles.com/non%20console%20manuals/fisher%2080az%20sm%20om.pdf

The "Z-Matic" damping control is similar to what's used in the Crimson 275. But here, the purchaser is treated as an intelligent person who is interesting in the technical aspects of his new (and quite expensive) component. He can see what claims are being made and how to actually use the amplifier controls to best advantage.

But then, I guess it wouldn't be a Carver amp without all the sideshow hand-waving and mystical terminology.

 

[abdo123]

Amir should have listened to it.

And risk blowing a 4th fuse ?

 

[traderitch]

So you concede the prime facie elements of a product liability suit likely exist here but hate corporate accountability and begrudge the factfinders a living. At least it’s a consistent position, I guess.

No, that was not the intent of my comment.
Again, we are discussing piece of audio equipment - not a pacemaker.
I do not believe this is the forum to have that discussion.
Please do not make assumptions about what I believe. I will state what I believe.

 

[mhardy6647]

High distortion and low power is literally the point of a tube amp.

well... maybe the distortion part.

Manley Neo-Classic 500W Monoblock — Manley Laboratories, Inc.

With the same topology as the Manley 250’s, the Neo-Classic 500’s continue the legacy of musical accuracy and emotional authority these amplifiers promise and deliver with double the output power thanks to the amazing KT90 output tubes.

www.manley.com

 

[mhardy6647]

The 'safety course' I had in high school was the AC/DC radio everyone built in electronics class. It became abundantly clear because of the 'hot' chassis that common sense needed to be applied to working with anything, well, on planet earth, be it electricity, driving a car, shooting a gun, or dating.

Thick rubber soled shoes. They won't prevent natural selection, but* they may delay it.

That being said -- there are other rubber products can help natural selection by preventing certain undesirable genes to be passed along to an unwitting next generation.
_______________
* for better or worse.

 

[teched58]

The latest from Jim Clark:

"You have a satisfaction guarantee for 30 days with a Bob Carver purchase from Jim Clark Stereo in which you can return the 275 for a full refund.. I encourage customers to compare these amplifiers in direct head to head comparisons to any other amplifiers of a similar power rating. I’m not concerned with sine waves and powering load resistors to be perfectly honest. Who listens to sine waves and load resistors? Thats pretty boring and tells you nothing about the amplifiers sound, driving music into speaker loads.

A site with ‘Audio’ in the title seems to ignore this point. Maybe the word Audio, implying sound, should be changed to ‘load resistor’?

I carry products because they are musical and sound great within their price range. I compare several models within a price point and listen to them with different combinations of front ends and speakers.

The units I can offer a satisfaction guarantee with, due to their musical performance are the ones I carry.

The unit has to play well with a variety of other gear and make the customer happiest to win, and not get returned.

The buck stops with the amplifiers performance playing music signals into speakers loads, and the 275 does this better than any I had listened to. Some were over 2x its price.

Customers should continue enjoying the very musical nature of this product, made especially for playing music into loudspeaker loads, and not be concerned with sine wave inputs and driving load resistors.

Use the 275 to play music into loudspeakers and it will make you smile every day without fail… Now if you want to stick your head between load resistors and play sine waves, buy something else."

Jim Clark at Carver Stereo Forum

Try small claims court. (You will have to sue your dealer, not the manufacturer.) General claims (aka garden variety b.s.) are not actionable. Such claims are called the "common puff of the salesman." However, SPECIFIC claims ARE actionable. So if you are sold something with the written promise that it will output 75W, then you might have a winning case. Here's an interesting page on puffery laws.