Carver Crimson 275 Review (Tube Amp)

[fpitas]

But to be fair the only dependable ground on the unit is the RCA shell.
And that is also used as its safety ground.

You shouldn't need much of a ground reference for a differential probe. In any event, that's how a user has to interface the thing.

 

[UncleMeat]

I have another question:

How scientific is an open poll to 'rate' an amplifier, when nearly zero of the respondents who gave it a rating ever listened to it? Or is this forum only purpose to support the 'result' of the 'tests'?

 

[fpitas]

I have another question:

How scientific is an open poll to 'rate' an amplifier, when nearly zero of the respondents who gave it a rating ever listened to it? Or is this forum only purpose to support the 'result' of the 'tests'?

Oh boy. He really let us have it

 

[Ken1951]

Oh boy. He really let us have it

He did, he shorely did indeed!

 

[fpitas]

He did, he shorely did indeed!

I can't recall anyone before this trolling us in that manner.

 

[Inner Space]

Damaging someone's reputation and product solely based on an incorrect analysis of it's performance ...

For avoidance of doubt on the libel issue - you, subjectively, come across as a sadsack butt-hurt fanboy, and the product, objectively, would have been mediocre and inadequate sixty years ago. In 2022, it's a cheap, cynical, careless piece of crap. OK?

Also, "it's" is a contraction of "it is" or "it was". The possessive form of "it" is "its". So you're also a little hobbled in the literacy department.

 

[UncleMeat]

Also, "it's" is a contraction of "it is" or "it was". The possessive form of "it" is "its". So you're also a little hobbled in the literacy department.

OMG I committed an apostrophe violation!! Is that the best you can do?

 

[Inner Space]

OMG I committed an apostrophe violation!! Is that the best you can do?

No, my point was apparently it's the best you can do. In other words it's indicative of your mental sloppiness and confusion, which, it must be said, shows up throughout your various contributions here so far. Why would anyone take seriously someone who can't even write the language he grew up with?

 

[BDWoody]

Damaging someone's reputation and product solely based on an incorrect analysis of it's performance, is a separate issue to the CE labeling/conformance.

Except that it wasn't.

You have had your say. You are done now.

 

[_thelaughingman]

Apparently the carver fanbois won’t give up the ghost of this review until the amp is in the grave

 

[PatentLawyer]

The amp uses a negative feedback loop to reduce distortion. Placing a piece of test equipment across the terminals of the speaker outputs will interfere with the feedback and cause the amp to distort. The distortion is then measured as 'error' but it's induced error due to the incorrect test method, not an error of the amplifier.

Heisenberg Uncertainty Principle in action?

 

[fpitas]

Heisenberg Uncertainty Principle in action?

No lol. It was actually a clever troll, implying that Amir was grounding the - output terminal of the amp. Amir uses a differential probe so no, he wasn't.

 

[PatentLawyer]

No lol. It was actually a clever troll, implying that Amir was grounding the - output terminal of the amp. Amir uses a differential probe so no, he wasn't.

Lol! I know. Just trying at every opportunity to combine my hobbies of audio and modern physics, even if it takes a bad joke.

 

[AdamG]

No lol. It was actually a clever troll, implying that Amir was grounding the - output terminal of the amp. Amir uses a differential probe so no, he wasn't.

That have to seriously up their game to survive this Crucible of a Group! Trolling here is next level work.

 

[solderdude]

I explained how it should have been tested at the bottom of page 117. You can't place any probe on the negative speaker terminal, it will cause problems with the feedback loop. If that's what happened in ASR testing, then all the results are invalid because the amp was oscillating and unstable.

I already explained. YOU are wrong it was measured correctly.
Besides many knowledgeable people on here have also explained about the measurement and that what you believe must have happened in reality could not even have happened. Your tech guy made that error. Amir did not and could not because the AP555 has a floating input.

OK, so Bob didn't follow CE standards on this one. Did I not mention that they rushed it a bit to market? Also, he was working with a new young man who he was giving a start in audio electronics. Maybe the correct 'labeling' was overlooked and they should have used a 2-prong IEC plug but the fact remains that the amp is safe how it's designed electrically. If you plug any 3-prong cord connected to it into an outlet, it's going to place the neutral on the correct side regardless, you won't get a backwards connection to the amp.

This is no excuse... sorry.
Also you are wrong. In Europe you can plug in a plug upside down. Effectively connecting 230V live via a 1M resistor to the chassis. One might hope the rest of the used gear is connected to safety ground in a proper way. It is even possible that this may cause a ground loop.

I don't really care about what you think I should hear. I let my ears tell me if it's good or not. Would I be listening to tube amps or SS amps that sound like tube amps if I wanted 'signal purity'? I want a sound that has the emotion of the original performance, and in general that can't be had with a sterile signal path.

So YOU want an effect box that pleases. That's fine. Most people want an amplifier that amplifies and does not add nor remove.

If the measurements were taken incorrectly (for this particular amp) then the results are invalid. I'm listening to it as we speak, without KT-120's in it (RCA 6L6GC) and it's got plenty of volume, more than I can handle for a few minutes without turning the volume back down. Now, if 6L6GC can drive the output to uncomfortable levels, what do you think the KT-120 can do?

Does your personal opinion change anything about the technical performance ?
If you are so convinced... send it in to Amir.

I don't know why they didn't use a bigger mains transformer. I'm thinking that maybe they didn't test it 'both channels driven' and see that it falls short in that area. Keep in mind that it had been many years since bob designed a 2 channel amp, all of his prior tube amps post-retirement were monoblocks.

No excuse either.

Then why are we arguing whether it's capable of delivering the base performance of 75 W/Ch?

I am not arguing. You are merely stating I am arguing. I agreed.

Either. It has a 5yr warranty if there are any real problems. Everything else would be a perceived problem and he offered an unconditional refund, he doesn't want your money if you are unhappy with it.

You perceive things differently than I... must be audio.

I think Jordon who Bob gave most of the product packaging work (and board layout) to didn't know about the proper 'markings' or that the IEC should have been 2-prong. I'm not saying mistakes were not made, but electrically the product is safe because the chassis is tied to it's ground.

That's what you think. A manufacturer SHOULD no. This is no excuse. Just one you came up with.

As I said before, if the tests were done correctly there wouldn't be this discrepancy between what real world owners/users are experiencing and what ASR test 'results' are showing. In addition I've shown that there is a known problem with testing this particular amp and how to correct the error in testing it. Bob couldn't put the test lead attachment point outside of the amp, so attaching to the RCA shell is the only alternative.

This has been covered extensively. YOU are wrong. The input of the AP is galvanically separated so the issue your 'qualified tech' encountered did not happen here.
So.. you can keep believing the measurement was incorrect but in the real world it was done correctly.

What makes the AP555 so immune to causing a problem when it's known that attaching test leads to the neg speaker terminal will cause problems? Obviously it's a sensitive feedback system that keeps the amp stable, so why argue the issue, why not just accept that there could have been an error in it's testing?

Because there wasn't. The input is 'floating'. It is you that is not accepting that fact.

Which is more plausible? An audio designer/physicist with over 60 years designing amps created an amp that sounds great but doesn't 'work properly', or a mistake was made in measuring it? Thousands of these units were sold, I don't see many going back because they don't sound good.

I did not say these amps do not sound good. It measures poorly... and yes... it was measured correctly. Even if you don't want it to.
If you have evidence of the contrary please post the 'correct measurements'.

Again, who is wrong? Maybe if you or anyone testing it had listened to the unit they would immediately know that your testing results do not equate to the performance of the amp in an actual application of, you know, music?

The testing WAS correct. Your ears aren't analyzers. You can enjoy music with ears+brain though.

Don't worry, I won't be selling my main system amps of these within my lifetime. And I trust the unpublished results of my EE friend who works on amps for people out of sheer kindness.

Ah right... the guy that had test gear that shorted the current feedback loop.
Why don't you ask him if you can set Amir straight and actually show the measurements.

It does when your non-peer reviewed tests (and unwillingness to accept that they -may- be wrong) are incorrect.

I did not measure anything here. And you need to accept that he measurements were correct.

If Amir agrees, maybe he should suspend this thread until there is verification that his tests were or were not done correctly. If not, it's possible that a bunch of libelous stuff was stated/posted here, and damaged the reputation of an audio legend over the last year because of 'vanity'.

YOU have to provide the evidence measurements were incorrect.
So far only false assumptions and your opinion have been posted by you.
No real evidence, no redemption.

Did you ever think of the possibility that this thread so severely damaged the sales of it, so that's why they stopped selling it? Marketing a particular product at a particular price requires parts purchases in bulk, so it's possible that there was an inability to risk buying the next lot of parts because sales plummeted.

They did not stop selling it. They are still selling it under a different name (the Black Magic 25) with more realistic specs.

No audiophool has ever been discouraged buying something that was tested on ASR. Reason: they do not visit this website and prefer NOT to see measurements. Mostly because they don't understand.

 

[Miiksuli]

That's kind of a slippery slope where we don't consider things that aren't close to SOTA. In this case, I'll argue that someone's eyes may have been opened. There are good tube amps out there. This isn't one. It's the equivalent of the cheap crap you find on eBay, but for a lot more money.

Can you point what is cheap crap at the ebay? My ebay buy costed me 1700€. It's China tube amp and I think its ok for the price. Not perfect but maybe some tube guru could mod it better.

 

[fpitas]

Can you point what is cheap crap at the ebay? My ebay buy costed me 1700€. It's China tube amp and I think its ok for the price. Not perfect but maybe some tube guru could mod it better.

Generally one of the big problems with that eBay stuff is the output transformer. Good ones are heavy, big and expensive. If yours is good quality, perhaps it's worth redesigning the amp.

Be sure to check your amp for AC safety, like Amir talked about. That's another problem with some of the eBay stuff, although it's more easily fixed. I'd demand that it has a safety certification before I bought one, but that's not common.

If you're trying to find a tube guru, there are a few on DIY Audio in the tube subforum. Some offer schematics and kits for good tube amps.

 

[Miiksuli]

Generally one of the big problems with that eBay stuff is the output transformer. Good ones are heavy, big and expensive. If yours is good quality, perhaps it's worth redesigning the amp.

Be sure to check your amp for AC safety, like Amir talked about. That's another problem with some of the eBay stuff, although it's more easily fixed. I'd demand that it has a safety certification before I bought one, but that's not common.

If you're trying to find a tube guru, there are a few on DIY Audio in the tube subforum. Some offer schematics and kits for good tube amps.

I have Muzishare X7. It weighs 22.5 kg. Company has a good reputation. I haven't looked inside on my unit but it should be grounded right. I may do it someday when I'm more educated and time for it.

At least this photo shows its.

 

[Gary_G]

PrimaLuna Evo 400 Tube Power Amplifier — PrimaLuna USA

www.primaluna-usa.com

 

[fpitas]

View attachment 249490

PrimaLuna Evo 400 Tube Power Amplifier — PrimaLuna USA

www.primaluna-usa.com

You spend a lot of money on interconnects. So why have the signal go right from the RCA jacks or speaker terminals into circuit boards with copper traces so thin you can hardly see them? What’s high-end about that?