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Carver Crimson 275 Review (Tube Amp)

Rate this amplifier

  • 1. Poor (headless panther)

    Votes: 366 95.6%
  • 2. Not terrible (postman panther)

    Votes: 5 1.3%
  • 3. Fine (happy panther)

    Votes: 4 1.0%
  • 4. Great (golfing panther)

    Votes: 8 2.1%

  • Total voters
    383

amirm

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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.
Carver Crimson 275 Review Stereo Tube Amplifier.jpg

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:
Carver Crimson 275 Review Back Panel Stereo Tube Amplifier.jpg


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:

Carver Crimson 275 Teardown Stereo Tube Amplifier.jpg


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:
Carver Crimson 275 Teardown Grounding Stereo Tube Amplifier.jpg


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:

Carver Crimson 275 Teardown VU Meter Stereo Tube Amplifier.jpg


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:
Carver Crimson 275 Measurement Warm up Distortion Tube Amplifier.png


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:


Carver Crimson 275 Measurement Stereo Tube Amplifier.png


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:

Best tube amp review.png


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

Carver Crimson 275 Measurement SNR Stereo Tube Amplifier.png


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

Carver Crimson 275 Measurement SNR a-weighted Stereo Tube Amplifier.png


Crosstalk was poor:
Carver Crimson 275 Measurement Crosstalk Stereo Tube Amplifier.png


Frequency response has an odd shape and good bit of loss at high frequencies with 4 ohm load:
Carver Crimson 275 Measurement Frequency Response  Stereo Tube Amplifier.png


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:

Carver Crimson 275 Measurement Frequency Response 8 ohm Stereo Tube Amplifier.png


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:

Carver Crimson 275 Measurement Multitone Stereo Tube Amplifier.png


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:
Carver Crimson 275 Measurement Power into 4 ohm Stereo Tube Amplifier.png


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:
Carver Crimson 275 Measurement Max and Peak Power into 4 ohm Stereo Tube Amplifier.png


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:

Carver Crimson 275 Measurement Power into 8 ohm Stereo Tube Amplifier.png


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:

Carver Crimson 275 Measurement Power vs Frequency into 4 ohm Stereo Tube Amplifier.png


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.

EDIT: We have had two formal responses from Bob Carver:

And one from Wyred4Sound that manufactures the unit:

And a bunch from one of their dealers, Jim Clark:
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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/
 
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amirm

amirm

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Holy... :cool: Half the house under water, tsunami warning, and you are posting a fresh review.
My utmost respect.
This one is on a short fuse so I thought I take care of it and also get a brief respite from flood work which I have to go back to now....
 

DonH56

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Alas, this is one amp that really is under water... (Sorry!)
 

Walter

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Your 4 ohm sweeps make it really hard to even say how this should be rated, as the amp is doing less than 2W above 5kHz.
Barely half a watt by 15kHz. So clearly it's a 0.5|14|29|60|75 Watt amp. :oops:

The 4ohm burst power might cover their claimed powered from a legal standpoint, but it is dishonest as hell. Carver was the very first brand/audio personality I developed a serious respect for from an engineering standpoint. Very sad to see that he/they have sunk to this level.
 
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DanielT

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Thanks for the measurement Amir! :)

Well what to say. If you are now going tube way see also relation to price, I think this seems interesting:
(think of service, possible recap and so on when considering a purchase)


This is just as interesting, see attached picture:


Advantage Dynaco ST 70. It is so famous. There is a demand. Just find out where the used price is usually in the country you live in. Buy and sell for more or less the same price. So you then you have tested on a tube amp. Or you may keep it, what do I know. The taste is different and varies.:)
 

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Blumlein 88

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Maybe it can make 75 watts if you have it on a 16 or 32 ohm load. Hahahaha!

Carver's past designs met or exceeded spec. I doubt he designed this either. Really a shame he is letting his name be used on it. More of a shame if he did design it.

Years ago I had a Carver receiver, and used it on some horribly inefficient Acoustat 2's. It played them fine which many people found hard to believe. This amp doesn't follow in that tradition. This one is thoroughly out-classed by a Dynaco St70 in good trim.
 

mhardy6647

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Holy... :cool: Half the house under water, tsunami warning, and you are posting a fresh review.
My utmost respect.

(I'd have pictured the panther standing in a puddle) ;)
Yeah, it's good to see someone with his/her/their priorities straight! ;)

This will make it pretty easy to return the amp to the dealer!
Sad but true.

Advantage Dynaco ST 70. It is so famous. There is a demand. Just find out where the used price is usually in the country you live in. Buy and sell for more or less the same price. So you then you have tested on a tube amp. Or you may keep it, what do I know. The taste is different and varies.:)
Plus -- the ST-70 has output iron commensurate in quality and quantity (i.e., mass) to its power output capabilities, permitting both reasonable output and reasonable bandwidth. Where things get really interesting is with a "high-end" push-pull EL34 amp like the magnificent (IMO) Marantz 8B.


PS If @paulbottlehead doesn't have 3A fuses handy, I can mail a packet of them to you @amirm or to Paul.
 
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Martin

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Sad… well at least I can take the Model 350 monoblocks off my list of desired products. I think I’ll refurbish my pair of Dynaco Mk III monoblocks or buy and build the pair of VTA M-125 I’ve been eyeing.

Martin
 

Digital Mastering System

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Maybe it can make 75 watts if you have it on a 16 or 32 ohm load. Hahahaha!

Carver's past designs met or exceeded spec. I doubt he designed this either. Really a shame he is letting his name be used on it. More of a shame if he did design it.

Years ago I had a Carver receiver, and used it on some horribly inefficient Acoustat 2's. It played them fine which many people found hard to believe. This amp doesn't follow in that tradition. This one is thoroughly out-classed by a Dynaco St70 in good trim.
I have a TX-11a tuner which I think is one of his best designs. The FM is great and the AM section is fabulous. On the other hand, I have also 'chip rolled' a C-2 preamp and while the overall design is OK the tone control and muting circuits in the C-2 are almost criminally bad. I had to rip them out and install properly designed circuits. (Just look at the tone circuit in HiFiEngine for the C-2 if you doubt me. I think the designer was trying to use the same log pots for the tone controls as he used on the level pot. Not a good idea.)
 

Blumlein 88

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I have a TX-11a tuner which I think is one of his best designs. The FM is great and the AM section is fabulous. On the other hand, I have also 'chip rolled' a C-2 preamp and while the overall design is OK the tone control and muting circuits in the C-2 are almost criminally bad. I had to rip them out and install properly designed circuits. (Just look at the tone circuit in HiFiEngine for the C-2 if you doubt me. I think the designer was trying to use the same log pots for the tone controls as he used on the level pot. Not a good idea.)
Yeah, the tuner in the Receiver I don't think was much different than the stand alone unit. It was by far the most sensitive tuner I've ever owned. Sound quality might not be the best, but it had some good RF performance. There was a college FM station broadcasting 15 watts (basically available on campus and the area around it for a couple miles). I did have a good large outdoor FM specific antenna on a rotor and mounted quite high, but I was able to get that station from 30 miles away which they couldn't believe.
 
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