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Need an audio brainiac...Stumped...

I just scratch built a "dynaclone" ST35 6BQ5 power amp from the schematic and stayed true to the dyna design save i used a 5u4 tube HV rectifier vice the diode dyna design.

The amp sounds fine on 3 different sets of speakers (Infinitys, Magnavox/Jensen alnicos, Realistic Nova 10's) but motorboats/farts when hooked up to my newly aquired Altec alnico Santanas. 2 other tube amps and 2 other solid state amps work fine on the Sanatnas.

This happens only with that one amp and speaker combination (Dynaclone and Altec Santanas)
trichifi

Showing 1 response by atmasphere

atmasphere's avatar
atmasphere
11,778 posts
 
If it were me I would look at the filter caps on the plate supply for the power tubes, even though this otherwise seems to be solved.

Motorboating is a classic problem of defective/inadequate power supply filtration. My guess is the amp is right on the verge of having troubles even if it seems to sound fine.

If the capacitance for the power tubes is inadequate, the amp will sound cleaner and more gutsy if this problem is corrected and it won't be subtle!
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