Carver Crimson 275 Review (Tube Amp)

[john2017]

As I understand it, the tubes pick up the vibrations created by the speakers. This causes the output tubes themselves to impart those vibrations into the sound.

 

[john2017]

What a load of crap. He knows zero about winding transformers. Most people do not, it’s pretty much lost art. The transformers are probably five dollars each from a Chinese supplier. The can is to hide they are junk, not for any legitimate purpose. Sad to say he’s not really a good designer, pretty much going on a puffed up reputation. Smh.

Bob is a physicist by education, and has more patents on truly life changing stuff than most people know or care to. He has forgotten more than most will ever know on Audio. He designed the amplification needed to simulate the harmonics of rocket launches and earthquakes. His work in that area has saved lives. He has designed medical devices and formed a company to produce them, saving even more lives.

I am not here to defend the 275, or refute the testing done here, but I won’t sit back and watch his character or his reputation be attacked either. As I said in my first post, I doubt Bob is even that deeply involved with the 275 to begin with.

 

[Blumlein 88]

Bob is a physicist by education, and has more patents on truly life changing stuff than most people know or care to. He has forgotten more than most will ever know on Audio. He designed the amplification needed to simulate the harmonics of rocket launches and earthquakes. His work in that area has saved lives. He has designed medical devices and formed a company to produce them, saving even more lives.

I am not here to defend the 275, or refute the testing done here, but I won’t sit back and watch his character or his reputation be attacked either. As I said in my first post, I doubt Bob is even that deeply involved with that to begin with.

Just going by this design he has forgotten most of what he knew about audio. He is the one doing the most to damage his reputation here.

 

[aj625]

such thin wiring ? so much 3rd harmonic distortion, what may be the reason ? unbelievable.

 

[john2017]

Just going by this design he has forgotten most of what he knew about audio. He is the one doing the most to damage his reputation here.

As was pointed out several posts back, Bob is not credited as having designed the 275. Please understand something. I know his name is on the box...l get that. However, Bob’s name still appears on products he has had zero involvement with in more than 40 years. He sold Sunfire 20 years ago, yet his name appears on every box. That appears to be the case on this one as well. Bob hates running companies, so Frank Malitz is running things under Bob’s name. It would not surprise me in the least if Frank joins here, being the vain, egotistical SOB he is and try’s to convince the masses that we are wrong. He may also reach out with a cease and desist order to take this thread down.

If there is a problem with the Carver 275, it rests with Malitz, not Bob.

 

[Spkrdctr]

such thin wiring ? so much 3rd harmonic distortion, what may be the reason ? unbelievable.

I believe that super thin almost not even there wire to the speaker connections serves multiple purposes. It acts as a fuse, a choke, and can help bring the unit up to operating temp. You get all three for the price of one ultra cheap, super thin wire. All you have to do is pass some serious current through that wire and all three effects will come into play. 3 things for the price of one. Simply amazing!

 

[solderdude]

I thought that was where they were going with it. But then, they started saying the feedback information is coming from the driver and the end result is fixing the room for near sonic bliss. I'm not sure I'm buying into that. OK, I'm throwing the red flag of BS.

It is very obvious from the PCB layout the speaker current is being measured as there is a 0.1ohm sensing resistor in series with the output.
For it to 'read the room' as a microphone is bollocks. Bob does seem to use the back EMF but most likely this is to compensate for the high-ish output resistance so the amp output is probably less impedance dependent.
The fact that one can use a speaker as a microphone In this case the speaker must be connected to a high impedance microphone input and not simultaneously to a near 0 ohm amplifier output. Back EMF and 'microphone' signal as well as applied signal can not be 'pulled apart' without complex math and fully characterizing the speaker.

Unfortunately this isn't verified measured as only a resistive load is used. A complex load could shed some more light but this doesn't have back EMF. It should be measured with a speaker and on top of that it should also be measured with no signal and a second speaker with a sweep on it directly in front of the speaker and then measure at the primary of the transformer what the amp does with it.

I voted poor because of safety features. It should have had a different mains socket (without a pin), a double insulated sign on the back and everything mains related should have had some shrink sleeving on it or the ground pin should have been connected.

One thing to keep in mind, given the power remains the same at various impedances, is that while it does not have spades of power available it does output 75W but will sound louder than a 75W SS amp (with any speaker but Maggies).
Most 'power' is needed in the lows for music and the impedance is highest there in speakers.
So a bass note into say 16 ohm will get 75W of power = 34V while at 1kHz (assuming no XO there) will only have 17V (assuming 4 ohm nominal)
A SS amp rated at 4 ohm would need to be rated at 290W in 4 ohm.

This is why a 40W rated tube amp can sound more powerful than a 40W rated SS amp.

Of course, this is cornering it a bit short as there are limits to the max impedance of a speaker where this will work and the speaker would have to peak at the frequencies you want to play louder.

In short... the claim Bob makes has not been verified. The claim of reading the room is bogus. The reflected sounds into speaker will be immensely small compared to the back EMF and the applied signal and cannot be told apart from the back EMF due to the huge level difference of back EMF and 'room reflections'. It simply is physically not possible.

Back EMF itself can be used (and most likely is) but this was not measured.
@amirm could measure it by 'injecting' a signal (using a SS amp output via a dummy-load) into the output of the Crimson and measuring on the speaker out terminals what signal remains. Then do the same thing with the current measurement resistor shorted.
This is a lot of extra work though and he has been quite busy with other (far more important) stuff.

 

[warnerwh]

If there is a problem with the Carver 275, it rests with Malitz, not Bob.

@john2017 You should go to post 169 and see the video Bob did promoting this amplifier.

 

[aj625]

I believe that super thin almost not even there wire to the speaker connections serves multiple purposes. It acts as a fuse, a choke, and can help bring the unit up to operating temp. You get all three for the price of one ultra cheap, super thin wire. All you have to do is pass some serious current through that wire and all three effects will come into play. 3 things for the price of one. Simply amazing!

i thought there is provision of fuse already.

 

[john2017]

@john2017 You should go to post 169 and see the video Bob did promoting this amplifier.

No need... I saw him promoting one in person. That said, he is not the one building them. I believe he built one that does exactly what he says it is capable of. This is very different to what is being built in his name.

 

[DSJR]

Thanks for that. Another valve fave (for reviewers: I"ve never heard one) was the Michaelson & Austin TVA. I did hear a Beard valve amp somewhere once and it sounded not bad at all, FWIW.

TVA1 was a potential fire hazard and they ruined it as they tried to squeeze more and more power out of the design. TVA 10 was a milder amp but a bit ineffectual. the bolt-up Naim 250 pre 1980 was a better valvey-sounding amp, this before they turned it into a domesticated PA amp 'sound,' all hard and up-front. There was one Beard model (in a gold finish) that was well liked I recall and our service engineer swore by his.

 

[john2017]

It just occurred to me that these amps are not the 275 (2x75wpc), but rather the 27.5... they simply forgot the decimal point. Now that this has been cleared up, maybe we can find another dead horse to beat.

 

[warnerwh]

I wonder why the dealer that sold the one that Amir tested didn't know these are the 2x7.5 wpc amps.

 

[Blumlein 88]

No need... I saw him promoting one in person. That said, he is not the one building them. I believe he built one that does exactly what he says it is capable of. This is very different to what is being built in his name.

Delusional faith by audiophiles is amazing. More than many religions. He personally publicly promotes this very amp, and it has his name on it, but we are to ignore that and say it is on some Frank guy we've never heard of before? Not Bob's rep being hurt on no. You can't make this stuff up.

 

[john2017]

I wonder why the dealer that sold the one that Amir tested didn't know these are the 2x7.5 wpc amps.

My post was meant in jest. For some reason I cannot attach a smiley when posting from my IPad

 

[john2017]

Delusional faith by audiophiles is amazing. More than many religions. He personally publicly promotes this very amp, and it has his name on it, but we are to ignore that and say it is on some Frank guy we've never heard of before? Not Bob's rep being hurt on no. You can't make this stuff up.

We Ask 10 Questions For High-End Audio Manufacturers Featuring Frank Malitz, Former CEO And Co-Founder Of Bob Carver Company

We Ask 10 Questions For High-End Audio Manufacturers Featuring Frank Malitz, Former CEO And Co-Founder Of Bob Carver Company

www.enjoythemusic.com

Based on reading this, Bob does not own this company any more. He is just an advisor, while Frank does the rest.

 

[Larry B. Larabee]

I believe that super thin almost not even there wire to the speaker connections serves multiple purposes. It acts as a fuse, a choke, and can help bring the unit up to operating temp. You get all three for the price of one ultra cheap, super thin wire. All you have to do is pass some serious current through that wire and all three effects will come into play. 3 things for the price of one. Simply amazing!

You forgot the variable impedance due to increased (heating) wire resistance. Or as BC would say dynamic motional feedback processes that control low frequencies through thermal cycling of the thingamajig.

 

[amirm]

I believe that super thin almost not even there wire to the speaker connections serves multiple purposes. It acts as a fuse, a choke, and can help bring the unit up to operating temp. You get all three for the price of one ultra cheap, super thin wire. All you have to do is pass some serious current through that wire and all three effects will come into play. 3 things for the price of one. Simply amazing!

The sample from another member has larger gauge wire. So clearly it is not part of the design but rather, whatever wire is available at the moment.

 

[Blumlein 88]

We Ask 10 Questions For High-End Audio Manufacturers Featuring Frank Malitz, Former CEO And Co-Founder Of Bob Carver Company

We Ask 10 Questions For High-End Audio Manufacturers Featuring Frank Malitz, Former CEO And Co-Founder Of Bob Carver Company

www.enjoythemusic.com

The Chief Designer is Bob Carver. Or so this says.

Then it says a lot of stuff like the 275 being really 90 watts. A tribute to Frank McIntosh, and later Stu Hegeman of HK Citation fame. Wow!

And again the idea it can repair a defective output tube, and this is the first place I noticed they claim a tube life of 26 years (45 years in the 350 model). I think I'll buy one, get all the defective output tubes I can, play them a few hours in the 275 until they are repaired and then sell the tubes for a profit. What do you think?

 

[john2017]

The Chief Designer is Bob Carver. Or so this says.

Then it says a lot of stuff like the 275 being really 90 watts. A tribute to Frank McIntosh, and later Stu Hegeman of HK Citation fame. Wow!

And again the idea it can repair a defective output tube, and this is the first place I noticed they claim a tube life of 26 years. I think I'll buy one, get all the defective output tubes I can, play them a few hours in the 275 until they are repaired and then sell the tubes for a profit. What do you think?

I think that if Frank Malitz says it, then it must be a lie. Like I said... Bob gives him a product that does exactly what he claims it does, then Frank cheapens the crap out of it and we get the garbage found here. I bet if Bob knew what was done to the 275, he would blow a gasket. That is not a pretty sight.