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My 30 Watt class A is louder than my 100 Watt Class AB?

Curious observation…

I had just done some work on my DIY Hiraga 30 Watt Class A amp, and decided I would do an A/B comparison with my Adcom GFA 545.

To my great surprise, when I switched from the Hiraga to the Adcom, leaving everything else in the set up the same, and when I turned the music back on, it needed to be turned up to play at the same volume.

Input impedance is different, and I’m wondering if this is what could be causing this counter intuitive finding? Hiraga is around 33K and the Adcom around 100K.

Wondering if anyone has any thoughts as to why this is what I’m experiencing.

Thanks

 

perkri

Showing 1 response by carlsbad

carlsbad's avatar
carlsbad
1,551 posts
 

Amp settings vary with gain.  I recently use the same preamp into two different amps, one of whiich can use 3 tubes for different power levels,  with the following results for the same voume level.

ZMA  40 wpc  -40dB

Techtron 300b 6 wpc   -45dB

Techtron 2A3  2.8 wpc  -48 dB

Techtron 45   1.8 wpc   -50 dB

So the gain produces the same valume at a lower setting but if I were to turn it up on a night when I felt particularly sadistic toward my eardrums, they woulld run out in order of power from low to high.

I thought it was ironic that the lower the power the more gain.

Jerry

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