Dynaco PAS 3 Mods

Hello,

I bought a PAS 3 preamp in 1976 from a small audio shop in Pa. called OPUS ONE. I had them build it. They offered a modification for some extra money which seemed like a good idea but I really never got any idea what kind of a mod it was. I didn't get a schematic (and wouldn't have known what it meant at the time) but I will say the PAS has always had a wonderful transparent sound.

It was modified by a technician name John Barletta (it is signed inside). If anyone has an idea about the nature of this mod it would be appreciated.

Also, Rich N..... if you read this, email me, Bob H...

Bob,
can you take clear pictures of the top and bottom and post them here, we might be able to figure it out.

Thanks,
Sal

Bobh emailed me 8 pictures to post here. I resized the to 42 percent of the original size.

Bob,

I would say "modified" would be putting it mildly. Here's what I see...rebuilt power supply, rebuilt line board with tone controls, filter control, and loudness control bypassed and/or removed, and a replacement volume control. I'm glad this worked well for you, but I can't give any compliments to the tech on his wiring work.

Finally, I presume this unit is no longer functional because the left channel wafer on the selector switch looks like it has disentegrated (half of the wafer is hanging off to the side). I believe this unit is a good candidate for a ground-up rebuild!

Best Regards,
Charlie

Charlie,

Just to set the record straight, the rectifier and volume control were replaced due to failures over the last 35 years and I am the one responsible for any sloppy wiring. As for the removal of the tone controls, loudness control, that was part of the design of the mod. I knew that.

The selector switch broke apart last week. Up to that point , yes it worked well. I think I will do a little more research before I decide to rebuild. I appreciate the comments tough.

Bob

Bob,

I hope I didn't sound too harsh, I was just honestly commenting on what I observed from the photos. Seriously though, If you still have a place in your system for your PAS I would really encourage you to consider doing a restoration or rebuild. There are many options available for refurbishing these preamps and you can still get many more years of enjoyment from it by investing a little time (and a few bucks, of course!).

Best Regards,
Charlie

Charlie,

Not to worry, I understand. In regard to the restore, I have had other PAS pre amps before and this one just sounded better, more transparent. I may some day do a rebuild but not yet. I think my easiest route is to locate an original style selector switch. I presume they are available.

Thanks, Bob

Dear Bob H, I hope this finds you and yours well. I AM the one and ONLY Jon* A Barletta who used to manage opus one, Indiana, PA, and who modified your PAS. The parts and design of the kit which not only included the power supply regulator and new caps and resisitors was from a company which advertised in THE AUDIO AMATEUR magazine in the middle 1970s. It's a compliment to me that it's lasted so long and served you so well. The hot Dyna setup then was to upgrade, the well, let's be honest, CHEAP Dyna parts [except their transformers which were excellent] to more like Audio Research parts. (ARC started in business modifing Dyna stuff...and offered Dyna modifing kits.) By the way, what brand[s] of tubes does your PAS have? Be well, Jon A Barletta jonbarletta@yahoo.com *I got the "H" beat out of me as a child.

Jon,

Thanks for responding, I hope you yours are doing well also. I want to thank you for the years of enjoyment I have gotten out of my PAS, as well as the Vestigal Tonearm I got at Opus One. They were some of the best purchases I ever made. As for the tubes in my PAS, they are a combination of Sovtek and Telefunken 12AX7's. I remember having a problem with a ringing overtone that went away when I bought new tubes. I have since had those tubes tested and they tested ok. So it must have been something else. I still have them as well as the replacement set. I think they were the Sovteks. I recently located some new switch biscuits and I am preparing to rebuild the broken switch from end to end.

Take Care, Bob