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Cool running, low powered power amp

My regular amp is a Class A, all tube (KT 88’s) affair that runs very warm. For most of the year, it doesn’t matter. But in the dog days of summer, it can become unpleasant in my smallish listening room, where the AC doesn’t reach as well.

My speakers are Volti Razz, which are something like 97 db efficient. My big tube amp is out in California getting repaired, and at the moment, the Volti are enjoying time spent with a Scott 299A. Those 17 wpc are plenty (and sound way better than a 65 year-old amp with original tubes (or at least, tubes marked "H.H. Scott") should. Volti says it only needs to be 8 watts to do the job.

I was thinking of First Watt, or maybe Pass Labs XA 25. But both of those are also Class A. But maybe all Class A are not alike in terms of generating heat. I am not anti-class D, and have had two Class D amps that sounded good, but I’d be more interested in A/B, or cooler running Class A. I'd like to bring it in under $3000, and I am a big fan of used equipment.

Thanks,

David

 

dtorc

Showing 3 responses by yyzsantabarbara

yyzsantabarbara
4,570 posts
 

Since you have Class A already why not try something different.

The Benchmark AHB2 is a good choice for very efficient speakers because it is quieter than anything else you may have heard. Some say sterile in sound but I think it is a super clean and smooth sound. I traded my last AHB2 a few days ago and I know I will miss it since there are no other amps I have heard that can do what the AHB2 to can do.

If you want to stay with Class A and also want to save a lot and I mean a lot of money, consider the Schtt Aegir 2. I have the Aegir 1 which is all Class A and I use for my headphones since the 20 watts suffices for that. My prior version can be had for about $500.

I was too late to buy a used First Watt amp for the same use. That cost about $3k. I decided to try the Aegir since it was rumored to be about 80% of the FIrst Watt. It was more than good, and I am happy with it. The Aegir 2 is supposed to eliminate some tiny mechanical noise from the amp.

Benchmark has a 30-day home trial.

Schitt has a 15-day home trial. 

BTW - there is a person is the SF Bay Area selling a KRELL Duo 175XD for a tiny bit more than your max limit. I owned this Class A amp, it does NOT run hot, and it sounds great. Only a local sale though.

 

 

yyzsantabarbara
4,570 posts
 

Class A is always going to run warm. 

Companies like KRELL and Westminster Labs say their amps are Class A and they run cool. The KRELL Duo 175XD that I owned ran cool and sounded like other Class A amps (maybe better). That was up to 175 watts of Class A, when needed. I also own a great Class A amp, the CODA #16 so I have a good frame of reference for the KRELL.

Companies like Gryphon say that the iBias based Class A such as the KRELL are not real Class A. You need to waste electricity for true Class A.

The new KRELL KSA i400 is the next version of what I owned. I expect that to also run cool-ish. That amp is 400 watts Class A at 8 and doubles to 800 and again to 1600. I think it is only 400 watts class A at all impedances.

yyzsantabarbara
4,570 posts
 

@lanx0003 The KRELL Duo 175XD was used on my Thiel CS3.7 and also my RAAL SR1a earphone using the older amp interface box. Interestingly, the SR1a drew more power out of the amp. I knew this because when I used the CODA #8 in place of the KRELL I could see the meters on the amp flying for the SR1a but not move for the Thiel CS3.7. I had both KRELL and the CODA on hand.

When I used the KRELL as a earphone amp I had the amp about 1 foot from my seating position. I never heard the fans.

Here is something on both the KRELL and Westminster Labs amps that I posted about earlier. Class A amps that stay cool.

WestminsterLab, LampizatOr, VSA and Hear This | AXPONA 2024 - Part-Time Audiophile (parttimeaudiophile.com)

I now use the Schitt Aegir amp in place of the CODA and the KRELL using a new RAAL amp interface box. It is rather good, not as good as the CODA or KRELL, but I only need 20-watts Class A with the new RAAL amp interface box.

The Aegir is mechanically nosier than the KRELL with fans. The new Aegir 2 is supposed to remedy that mechanical noise.

The CODA #16 does get warm generating the first 100 watts in Class A, but it is not very hot.

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