How to replace volume pot in Dynaco Pas

BTW, the Dayton caps only come in the values needed for the coupling caps, not the RIAA caps.

I noticed that when I started looking at the values.

This Pas has been rebuilt, but it was done before I bought it. The 250k pot is too sensitive and the pre sounds very good. I am wondering if the guy that did the mods changed the values toward the good. Should I start over and make sure that everything is ok? This is where I am leaning.
I feel like this little Preamp has alot to offer for a beginner hacker.
I really appreciate your help V.

e

It's fun to tinker but, if you like the sound, and like the orange drops (mylar caps come in various shades of red/orange all referred to as orange drops) why screw with it? I wouldn't. It is more than possible that you could make it worse.

Why not get a stock Stereo 70 to go with your PAS and beat on that? Or even another stock PAS and hack on that? The benefits of starting with stock is, first you know where you are, and second, you are not paying for someone else's work that you are just going to re-do.

But, should you prefer not to follow that bit of advice, e-mail me a photo of the phono stage and maybe I can figure out what has been done.

Then again, completely redoing the phono stage per Joe's suggestion, and changing out the volume pot to a 100K unit is very inexpensive.

I'm still hoping that Ralph checks back into this thread with some of his brillant ideas. I'm just a hacker.

Viridian: a St70,though very interesting to me,would never work with my speakers (Acoustat 2s).
Correct me if I am wrong,but Joe's circuit removes some of the caps to be replaced by wire? He seems to have a handle on the RIAA curve. I will send you some picts of my Pas board.
In the meantime, I definetly plan on changing out the rectifier for a new power supply cap board,and change out the pilot light for a diode. I feel like the volume pot is way off from where it should be. Honestly I really don't have a grip on that yet.Will having a 100k pot make it less sensitive?

I love it that Ralph jumps in on these strings. It proves to me that he has genuine interest in our hobby and makes me more interested in his products than others.(not to mention the great write ups his amps get)

thanks again

e

Wow yes, the 70 is not an appropriate amp for the 2s; that is for sure. Although, back in the day, my dealer was running 2+2s off of conrad-johnson MV-50s in mono, which are pretty much the rich man's Stereo 70. It sounded great, but did not play loud enough for me.

I really don't know if the 100K pot would make a difference in gain, but I suspect not.

When you do the cap board, don't forget to put in a power line fuse. It's strange, and dangerous, that they did not put one in. I think that the PAT4 has one, but I'm not at home to check my PAT.

Yes, one of the caps in each channel is deleted in the Curcio RIAA fix; hey, that's one less cap to buy!

Good luck with the build.