Magnatone MP1 trouble

[Helmholtz]

Hiss is not typically a power tube problem.

BTW, the amp had a gorgeous reverb sound.

[mozz]

I don't think new 7189 are going to withstand the voltages old 7189A would.

[Helmholtz]

Plate voltage limits are the same, but screen voltage is only 330V for 7189.
Of course an EL84 won't stand 400V+ at the screen either.

[pontiacpete]

I went ahead and order some NOS GES 7189A. Thanks for the help guys!!

[mozz]

I'm afraid to ask what the going price is for those.

[pontiacpete]

About $150 for a matched pair. I went with tubedepot, matched and burned in for $162 no shipping fee. Could no be worse

[Helmholtz]

As I really liked the reverb sound in the clip, I took a closer look at the special reverb circuit of this amp.

For the driver they are using a LTPI configuration as a self-splitting class A PP power amp.
Reverb output is fed to cathode of V3, where it gets mixed with the dry signal.
Tank output impedance should be low.