Tubes Asylum Questions about tubes and gear that glows. FAQ

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Some thoughts...

Posted by Phil Sieg on August 24, 1999 at 06:28:09

In Reply to: Re: Need help on 2A3 VS 300B differences. posted by DannyB on August 24, 1999 at 05:58:48:

Lower power does not, in itself, necessarily mean lower parts count and/or more "refinement". Parts count is related to how the circuit is realized, particularly how the driver stage is coupled to the output stage. Quality of parts is improtant, and none more so than the output transformer. But the designer's choice of operating points for both the driver and output tubes, as well as the design of the driver stage has the greatest impact on the final sound.

Cary amps have consistenly carried published power ratings that are on the high side. The KR2A3 is spec'd at a maximum power output of 3.5W. One way to get more is to drop the primary impedance of the output transformer. The only problem here is lowering the primary Z not only increases power, but it also increases distortion. Another way is to run the output tubes hot and hard, say at the max ratings. Problem here is that tube life is shortend and the Kr are $400/pair.

None of this is to disparage the Cary amps, for they are fine products. I own a Cary 300SEI. But you are paying a lot of money for those slick chassis. There are other options that are less expensive and use better quality output iron than Cary. Check out Wright Sound and Electric Tonalities. The ET offerings can be bought as kits or assembled. both of these companies offer 2A3 amps that are direct coupled, thereby simplifying the circuit over transformer coupled or RC-coupled designs.

check the link below for a little more info on the output tubes.

• Doc's 2A3 vs 300B vs 45 comparison

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