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Hello all beautiful Sunday here!!!
Last night I recaped and fixed up an old rca victor stereo console amplifier let it power up on the variac over night and today while I was trying out different sets of speakers I came across a problem with the amp with a certain pair of speakers I have.
These speakers
are called aspens they are full range and have no crossover in them. Each speaker has an audax 5" driver in it.
When I hooked them up the ocillation is very high pitched and only comes from one channel, I tryed shorting the inputs on both channel with no change.

On audiokarmas site theres a few threads about this amplifier and I did some of the suggested mods to bring the negative feedback up to get more gain out of the amp.

It sounds fine with all my other speakers that have crossovers in them. Any one ever ran into this with fullrange drivers ?

here is the schematic the values in gray are what I changed to.
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Hi,

Some amplifiers go nuts with FR speakers as some are really hard to drive (impedance spikes). A Zobel network might help here.

Cheers!

Can a SE amp with no NFB oscillate with a full range driver?

king I have another old stereo console amp its SE 1 12ax7 up front driveing 2 el84's no feedbacker it drives those aspens wonderfully. On the rca amp Iv checked afew more things like ps can leakage I added some bypass amp seems a bit smoother now I havent tryed the aspens on it again but its sounding pretty good. Need to add grounded plug and better input jacks!!!!

Great to know. My Sonido horns were slowly oscillating when connected to my Stealth (12A6-PP), but my TangDand (5"+1 1/4") dosn't. Could THIS be the problem??