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PAS-3 with ST-100

J

jszlau

New Member
I recently acquired a PAS-3 with its original tubes. The seller included an ST-120, one of Dynaco’s first SS amps. Beyond recapping, anyone have any advice for (or experience with) this pair? Google keeps noting the impedance mismatch.

Thanks!

Edit: typo. ST-120, not 100.
 
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whats the input impedance on the ST100? I claim zero familiarity.

The PAS can be easily modified to drive a lower impedance to a point. Basically just involves removing a resistor across the output jacks.


has an in-depth analysis of the whole thing, but the TL;DR version is this

1790014504261.png

so I read that as saying provided the ST100 isn't less than 100K, the PAS can be made to work just fine with it.
 
Ah, ST120, I've heard of that one. Even heard one on Friday.


so no big deal, change the 62K on the board to a 100K, remove the 510K at the output jacks and you should be good to go.

1790015703217.png
 
jszlau said:
I recently acquired a PAS-3 with its original tubes. The seller included an ST-120, one of Dynaco’s first SS amps. Beyond recapping, anyone have any advice for (or experience with) this pair? Google keeps noting the impedance mismatch.

Thanks!

Edit: typo. ST-120, not 100.
Click to expand...
It will work with a small adjustment ( remove the 62k resistor at the output)
BUT : don't start changing capacitors on the boards they are just fine! What might be needed eventually is
the B+ capacitor, but it would be better to install a zpsu board that replaced all power caps with modern capacitors without changing the design of the cirquit. Wait until you have used the PAS and may have identified any trouble.
 
Sorry — one last question. Would it make more sense to just run the pas through a line level input on a regular SSI amp?

ETA for the sake of reliability if I’m already making adjustments
 
Update my Dynaco has upgrade kits for Dynaco amps and preamps.
Link below:

Update My Dynaco

Updatemydynaco makes audiophile kits that make your Dynaco Stereo 120 Power Amp or PAT-4 Preamp even better than new.
www.updatemydynaco.com
 
No point in using the PAS at all if you're feeding it into the aux input of another preamp or integrated amp.
 
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