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Carver Crimson 275 Review (Tube Amp)

Rate this amplifier

  • 1. Poor (headless panther)

    Votes: 379 95.0%
  • 2. Not terrible (postman panther)

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

    Votes: 6 1.5%
  • 4. Great (golfing panther)

    Votes: 9 2.3%

  • Total voters
    399

DHT 845

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Wouldn't it be more reasonable to buy a solid state amp at a 10th of the price and simulate the THD and the mains hum by DSP?;)
You cannot simulate low damping factor amp - speakers interaction :)
 

ZolaIII

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@amirm don't use salt based dehumidifiers if salt gets in the walls you will have permanent problem. No need to comment on amp, pool says it all.
 

bidn

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There are some solid state devices that chug down lots of power! I have a solid state amp sitting around that consumes 300W at idle when it's on!
Of course it is possible to create very powerful or inefficient devices, but one should comparable what is comparable: building equivalent circuits, one with tubes, the other one with transistors, and compare the energy consumption for the same output...
This is what I mean by saying that these outdated tube devices represent a huge waste of energy compared to solid state ones.

(and this, again for equivalent circuitries, for an awful performance re. the quality of the signals output, as established by measurements).

(and what about the life expectancy of the tubes compared to transistors, or the energy required to make them?)

So for me, tube devices, since we are in a solid state era, are not merely snake oil in our time, but also a big waste electricity, unless one needs them to heat up his house during the winter time...
 
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DHT 845

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Add a 4 ohms resistor to the speaker cable...
How and for what? 4 Ohm resistor is supposed to change solid state amp with damping factor of for ex. 800 into "tube like" amp with damping factor of 2?
 

Limopard

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How and for what? 4 Ohm resistor is supposed to change solid state amp with damping factor of for ex. 800 into "tube like" amp with damping factor of 2?
In my understanding the damping factor is the speaker impedance divided by amp output impedance. Adding a resistor in series should change that significantly. But maybe I'm thinking wrong / too simple here. I'm not an engineer.
 

DHT 845

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In my understanding the damping factor is the speaker impedance divided by amp output impedance. Adding a resistor in series should change that significantly. But maybe I'm thinking wrong / too simple here. I'm not an engineer.
So you make DF higher.
 

NYfan2

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Good to see that all 111 people who voted agreed that this amplifier deserves the headless Panther.

Also thumbs up for @paulbottlehead for sticking his neck out to publish the problems and faults of this amplifier (and getting a shitload of comments about it) and then having the courage to buy another example from his own money to prove his point!

Finally again big thanks for our host @amirm who tested this amplifier on such a short notice.
 

Vladimir Filevski

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4 Ohm resistor is supposed to change solid state amp with damping factor of for ex. 800 into "tube like" amp with damping factor of 2?
Yes - but only the output impedance part. Bob Carver did exactly that (but with 1 ohm resistor) in the TFM range of Carver amplifiers.
To be completely tube-like, SS amp need additional distortion components, which can be generated in various ways.
 

SIY

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You cannot simulate low damping factor amp - speakers interaction :)
Of course you can. A little series-derived parallel-applied feedback does the trick perfectly.
 

Miiksuli

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What the man in question thinks about it:


Edit:
As I said, as others have pointed out in this thread. If you are going to have a tube amp, buy a well-proven classic like Dynaco, for example, or a brand / model that is sensible and popular in the country you live in.:)

By the way, I think tube amps are best suited for tube amp DIY people, who like to keep on tinkering.:)
'Has one very unique feature it knows how listen the room. No other amplifier that listens the room and modifies it's signal and soundstage to make the room as glorious that can possible be done with the musical sound stage.' -Bob Carver

What? Was this a joke?

Oh man. Good SE Triode amps have 2nd harmonic like -50dB and with lower like -60, -70dB higher harmonics. This PP Carver amplifier measures bad.
Yes. Even ultralinear is good when needed more power.
 

AudioSceptic

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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.
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.

-----------
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/
This would be terrible for a cheap product, but inexcusable for nearly $3k!. Bob Carver should be embarrassed and ashamed of his name being on this.

From a Brit perspective, I wonder how it compares with an original (1950s) Quad II or Leak TL12.
 

JayGilb

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I own several Carver products and have noticed a major slide in design quality for over the last 20 years, so this does not surprise me.
Bob was a great engineer and a even better salesman, so to see him spend his early career pulling back the curtain on audio BS, only to slide
it back is sad.

A few weeks back I didn't think Bob was involved in this design and know I'm pretty sure that Ms Hologram was the lead engineer.
 
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DanielT

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'Has one very unique feature it knows how listen the room. No other amplifier that listens the room and modifies it's signal and soundstage to make the room as glorious that can possible be done with the musical sound stage.' -Bob Carver

What? Was this a joke?
Waffle from Bob Carver. He wants money, hence it is praised.Or whatever the reason is that he says what you quoted.

There have been some Hifi products that have been disappointing lately. That with brands that everyone knows. Had it been any unknown manufacturer who had made this tube amp, I would have just stated laconic: Expensive shit ... but that it is Bob Carver. It's sad.

Some examples, well-known Hifi brands with rather lousy performance in relation to price::(

Amplifier:
Rega IO: US $ 649
Hegel H95: US $ 2000

Speaker:
KEF T101: US $ 650 for a pair.
Wilson Audio TuneTot: Insanely expensive speaker: US $ 10,000
_______

On the contrary, good performance in relation to price::D

Amplifier
Topping PA5: US $ 349
In need of more Power then:
Hypex NC400 DIY Amp:
about USD $ 1,100

Speaker:
Ikea SYMPHONIC Picture Frame Speaker: US $ 199.
Beyond that, if one is to compare Wilson Audio TuneTot, given its price. Well take any Revel for example.

Amir has measured and tested the above-mentioned Hifi products and for those who are interested, they can be found here:


 
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DHT 845

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Of course you can. A little series-derived parallel-applied feedback does the trick perfectly.
Any link to such a trick? Is it comercially available somewhere?
 

Dennis_FL

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Frank Malitz: “I made more money!”
Wow…..maybe the reason for ground problems, glueing meters, poor performance. but a nice plaque with Bob’s name on it.
 
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Mnyb

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You cannot simulate low damping factor amp - speakers interaction :)
Or the saturation of the output transformer in the bass , what a strange effect box it will take barely noticeable lf tones and instead give you odless of thier harmonics in a more audible range .

This would have been better marketed as a 15wpc tube amp with unusual high dynamic reserve . If I understood that’s the novelty of the design.

But it is more of a prototype “ proof of concept “ design it performs to bad to be put in use as amp by real customers?

Why it works ? I would look at the spectral content of music it’s not much at the extremes 20hz or 20kHz if you you don’t stress it to much you can sort of use this amp .
But I bet even those folks that don’t put such a high demand on thier amps would find recordings and situations where this performance is not good enough. That’s why we have modern ss amplifiers , they just works and are rarely the bottleneck in your hifi system.
 

anmpr1

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A few weeks back I didn't think Bob was involved in this design and know I'm pretty sure that Ms Hologram was the lead engineer.
Miss Hologram had much better specs, and likely much better 'hands on' performance, than this.

For me, it's kind of like watching one of your favorite stars, past his prime. Ali doing the rope-a-dope because he couldn't fight, anymore. Or Clint in his latest movie, trying to act like he's 30 years old. Of course, they had an excuse-- they were old men. We all get old and can't do what we used to be able to, physically. But as an engineer/designer, as long as your mind is intact, you should be able to create something of value, regardless of age. So it's not really the same thing.
 
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