understood.
How should it have been tested ?
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.
No it isn't from a safety design standpoint.
Obviously Carver used the correct mains socket (2 prong) socket and double insulated label on another of their designs so could have known. Not the same manufacturer though.
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.
I agree.
Not really.
The fact that you can get some more power out of it when saturating the magnetic core, most likely with a LOT of odd order harmonics, doesn't mean it is underrated.
Regardless what the excuses are.
He's not saturating the core, he designed a more efficient transformer. Bob does design his own transformers he's been doing it for many years.
You mean listened to it and liked the changes that are made to the original signal ?
In your opinion does an amplifier have to alter the recording in a way that is pleasing to you or does it have to amplify and not change the original signal in an audible way ?
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.
Not according to the measurements. It reaches the specified power level but does not exceed it and in low frequencies the output power is (not unexpectedly) much less than the rating.
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?
Amir said the following in his review (he is not responsible for what others are writing about Bob) I highlighted some important bits.
It isn't anything like a cheap version of a $10k 350W monoblock.
Not performance wise not build wise.
So if that were the goal it wasn't met.
Nope... but that's what you've been told.
It isn't.
My reference to the Crimson/Raven 350's was that Bob was attempting to replicate THE SOUND of them. He's done this many times in his career, building a a high dollar reference amp (Silver Seven) and then replicating it for a lower cost unit that is marketable (Silver 7t, Silver 9t, TFM). This was the design intent behind the Crimson 275. Yes, the goal was met if you care to listen to it.
How do you know ?
Did you compare the 2 amps side by side ?
Many people have, and their impression is that it sounds nearly identical to the Crimson 350's up to the point where it runs out of headroom.
20k for a stereo amp (2x350W) = $29/W and 275 = $20/W
I guess you are right... relatively speaking one pays less per Watt. That is if you want to make that particular point.
We listen to stereo = both speakers being powered at the same time.
Usually the bass is mono and that's where the majority of the power goes to.
This is not where the power is 90W per channel though... Yes, impedance usually goes up in the bass... this helps with a lot of speakers.
As shown above it meets 75W with a dynamic signal designed to gauge music peak power capabilities. not 90W.
The point was that if you have a system that doesn't require the higher headroom, you could buy one (or two) C275 amps and get similar sound quality for 1/4 to 1/2 of the price of a C350 set.
As I said before it's capable of 90W in a single driven channel, thus the concern over the output transformers is baseless. If they were only capable of 15W they would short out at 90W but they don't.
so 50-60W per channel...
Perhaps the design warranted a higher power rating for the mains transformer ? An engineering choice keeping costs down or deliberate action knowing that very short term peak power is available ?
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.
Then why are we arguing whether it's capable of delivering the base performance of 75 W/Ch?
Perceived or real problems ?
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.
No they are not. There are rules manufacturers have to comply with. Regardless if the manufacturer has a different viewpoint about this.
It is fine to make a double insulated device but it should be obvious it is.
There are no such markings nor test reports and the wrong connector is used as well. Most likely the guys assembling this either did not know about norms/regulations or did not care.
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.
I agree. For the same reason it makes no sense to use thick mains cables, yet that's what audiophools like.
In this amp, having a high output resistance by itself which varies with the load as well, because of the voltage+current feedback, and low power rating as well as short wire distance this is not an issue at all.
But that is only IF the tests were done incorrectly of which you have not put forward any proof.
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.
You were told porkies.
You see the input of the test equipment is isolated from the source signal.
When the test equipment were NOT isolated and the audio input ground were basically connected to the - output terminal and would basically have shorted the current feedback path and even might have 'injected' some speaker current right back into the amp as an unwanted input signal there might have been a point.
This is what happened to your 'tech wizard' who obviously does not know about he AP555 (see post above).
But there wasn't such an issue here which is evident in the measurements.
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?
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.
Nope it isn't, that just what you've been told and they were wrong.
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?
Personal opinion not based on reliable and verifiable facts... noted.
Why would your opinion invalidate the testing ?
Aaaahhh... I think most will agree.
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.
That might be the fact that the amp adds things to the original signal. If that's your thing enjoy it. Does not have anything to do with the testing and depends on the actual speaker load.
It does when your non-peer reviewed tests (and unwillingness to accept that they -may- be wrong) are incorrect.
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'.
This is about one particular amp that is no longer sold in the same form and type. That might be for a good reason. If Carver (not Bob) would have stood by the design he would have continued selling it the way he designed it.
I hope people read all of it. Warts and all and can arrive at a point where they decide to buy this particular amp or not... maybe another Carver model or look into different brands as well.
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.
BTW
carveraudo.com has been defunct for a few years. The two websites that discuss Carver and Carverfest are the following:
thecarversite.com
carveraudio.proboards.com
