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Crimson 275 ASR review


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https://www.audiosciencereview.com/forum/index.php?threads/carver-crimson-275-review-tube-amp.29971/

 

Amir over at ASR finished up the review of the brand new out of box production unit and the results were actually more dismal than expected. I enjoyed the review of course and I am certain this amp sounds fine at <15 watts which is fine for Klipsch speakers, the issue is people purchased this under the guise it can produce 75 watts per channel cleanly into rated loads with published bandwidth and distortion and it doesn't. I could understand any owners frustration and not sure what I would do, probably try and return it if I paid full price honestly.

 

NO SAFETY GROUND ON CHASSIS - Yikes!!

 

Meter glued to frame is low class for this price point.

 

Loose screw inside is scary for a brand new unit.

 

Pretty bleak.

 

If you purchase I high power tube amplifier make sure it weighs the part if it has output transformers.

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36 minutes ago, Shiva said:

Read the review earlier.  Not very glowing is it. 

 

I think some of the owners of these amps were hanging on to a sliver of hope this final test would show different results. There are going to be a lot of angry consumers looking for answers and refunds now, hoping the company bucks up and takes care of them on this. I really hope they don't deny these results and sweep this review under the rug with cease and desist orders from the court.

 

Curious to hear from some of the owners in this group to see what they plan to do. I don't think I could personally sleep at night letting this company get away with this and even if I really liked the amplifier I would probably ask for a full refund, there are plenty of great amplifiers you can purchase or have custom made for $2500.

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On 1/15/2022 at 4:32 PM, captainbeefheart said:

 I would do, probably try and return it if I paid full price honestly.

I would not mind buying one at a Discounted rate , then do  the right modifications -

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57 minutes ago, 001 said:

I would not mind buying one at a Discounted rate , then do  the right modifications -

 

That's really not a bad idea, I wonder how much they will drop on the secondary market after the smoke settles. At the very least the first thing I would do is make it safe. 30 watt Edcor output transformers are $100 a pop, but for $200 and maybe an hour of soldering you can make this amp much better. I believe the power transformer is under sized as well, and if you upgrade the output transformers you might as well throw in a larger power transformer for another $100 putting you at a grand total of $300. The hardest part of changing output transformers is re-calculating the compensation networks but still easy done.

 

I would like to have a closer look at this 'DC restorer circuit' during higher output level testing, I am willing to bet it hinders performance at the cost of increasing tube life. Honestly the way it was blowing fuses for Amir at such low power the DC restorer circuit will never come into function as the tubes require going into cutoff for the circuit to work. The tubes of course last so long with this amp because they are just loafing around low power and low bias with these amps, the 'restorer' circuit is a gimmick I am sure of it.

 

The mismatch plate loads for the LTP phase inverter are there to hope for balanced sections and get somewhat close to symmetry but it without adjustment it's a crap shoot to get symmetry. The best option and easy to do is just remove the 20k tail resistor and use a constant current source, make both plate load resistors equal and the CCS will force symmetry no matter what tube you install, no adjustment ever needed for perfect symmetry.

 

It would be optimal to regulate the power tube screen supplies so they don't sag under higher signals.

 

Rearrange the current feedback by adding 1 more resistor and a potentiometer to give you variable damping with both negative and positive current feedback.

 

 

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23 hours ago, captainbeefheart said:

 

That's really not a bad idea, I wonder how much they will drop on the secondary market after the smoke settles. At the very least the first thing I would do is make it safe. 30 watt Edcor output transformers are $100 a pop, but for $200 and maybe an hour of soldering you can make this amp much better. I believe the power transformer is under sized as well, and if you upgrade the output transformers you might as well throw in a larger power transformer for another $100 putting you at a grand total of $300. The hardest part of changing output transformers is re-calculating the compensation networks but still easy done.

 

 

 

 

they are using 15 watts Edcor output transformers ,the output stage is  way under-biased , no wonder the Tubes last , they are anything but warm  , you want to increase  bias , the transformers cant handle the quiescent current , no wonder the amp is so  light it's a 15 wpc amp  sold as a 75wpc  - 

 

I dont understand how they can test the amp at the rated specs  ,  and in order to safely reach the advertised 75wpc   , you would need 30 watt output transformers as a minimum ,plus as you said a decent power transformer ,  and + the added bias , or else , people are gonna damage 15 watts  transformers prematurely  and even risk a fire   before the warranty is expired -

 

anyway you look at it , these amps will not  last unless they are babied with very low usage -

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6 minutes ago, 001 said:

they are using 15 watts Edcor output transformers ,the output stage is  way under-biased , no wonder the Tubes last , they are anything but warm  , you want to increase  bias , the transformers cant handle the quiescent current , no wonder the amp is so  light it's a 15 wpc amp  sold as a 75wpc  - 

 

I dont understand how they can test the amp at the rated specs  ,  and in order to safely reach the advertised 75wpc   , you would need 30 watt output transformers as a minimum ,plus as you said a decent power transformer ,  and the added bias , or else , people are gonna damage 15 watts  transformers prematurely  and even risk a fire   before the warranty is expired , and anyway you look at it , these amps will not  last unless they are babied with very low usage -

 

That is why when Amir was testing the amplifiers the fast blow fuses would pop when testing over a specific power output, I think it was 27 watts. This is how they are avoiding transformer failures. Now it's possible they can claim the amplifier can produce 70 watts peak transient power for a very short duration and only in the midband, if not a short time period the fuse blows protecting the wimpy transformers.

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19 hours ago, 001 said:

they are using 15 watts Edcor output transformers ,the output stage is  way under-biased , no wonder the Tubes last , they are anything but warm  , you want to increase  bias , the transformers cant handle the quiescent current , no wonder the amp is so  light it's a 15 wpc amp  sold as a 75wpc  - 

 

I dont understand how they can test the amp at the rated specs  ,  and in order to safely reach the advertised 75wpc   , you would need 30 watt output transformers as a minimum ,plus as you said a decent power transformer ,  and the added bias , or else , people are gonna damage 15 watts  transformers prematurely  and even risk a fire   before the warranty is expired -

 

anyway you look at it , these amps will not  last unless they are babied with very low usage -

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12 hours ago, Westcoastdrums said:

Let you guess, yes. Have you heard it?  I have, and I have owned it with a damaged tube.  Sound was so good I debated buying it new slightly discounted.   What say you now? 

 

Nobody has said anything about it sounding terrible and nobody would have a problem if it was sold as a 15wpc amplifier. But selling a 15wpc amplifier as a 75wpc amplifier especially for the price is what the problem is. Add in the glued down parts, and lack of standard safety protocols and the Crimson doesn't look so appealing.

 

$2500 is a lot for a basic 15wpc push pull amplifier.

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10 minutes ago, captainbeefheart said:

 

Nobody has said anything about it sounding terrible and nobody would have a problem if it was sold as a 15wpc amplifier. But selling a 15wpc amplifier as a 75wpc amplifier especially for the price is what the problem is. Add in the glued down parts, and lack of standard safety protocols and the Crimson doesn't look so appealing.

 

$2500 is a lot for a basic 15wpc push pull amplifier.

OK, no argument there. I was, disappointed seeing the tear down and testing thereafter.  I won't beat this amp up as someone here owns one. 

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