Dynaco PAS 2 value and difference to PAS 3?

Emorrisiv, here are some tips if you are interested:

try to retain the rectifier tube. Replace all the filter capacitors. Replace the selenium filament rectifiers with 3A low voltage silicon devices.

Tape has become more popular, but usually the tape machines have their own playback EQ. So its a nice trick to move all the EQ components for the phono off of the switch and onto the bottom of the board. You can also wire the phono input directly to the phono board as a result. This eliminates the need for the middle wafer on the selector switch.

I've made 24-position stepped volume controls for the PAS that have worked out quite well! If everything is done right this preamp can challenge a lot of modern preamps, but it will not do LOMC without a stepup device.

Have fun!

Ralph here is my progress and plans.

I have bypassed the tone controls. All the caps have been replaced.(orange drops from the looks of them)
I replaced the funky bad balance volume pot and disconnected the loudness feature.
I added a couple of 47k resistors to the volume pot to help the taper.(much better)
I have a stepped attenuator coming.
I have a power supply upgrade board coming to get rid of the rectifier, but keeping the tube.

I would like to eventually get rid of the blend switch and the tape eq for more inputs, but that is low on the priority list. I only listen to LP,CD,FM and I have enough inputs for those already.

I have my SUT connected but I had to go back to the 15:1 ratio because there was too much gain. No problem.
It sounds so good. I am in tube heaven. Those old Telefunkens are sweet.

I feel like I have never really known what "inner detail' meant. This has inner detail in spades. Not to mention timbre and presence the likes of which I have never known.

I have to mention that I got a lot of help from George Regenesis. He offers Dynaco upgrade boards and was a big help to me so he deserves a shameless plug here. He also has some of the best prices too.

Ralph, would this mate up with the Atmosphere's MA-1?
I really want to hear those amps.Of course I would need some Zero transformers too.
I can't wait to go back to work and making a living.

e

Emorrisiv, the PAS can drive our amps just fine!

There is a way to eliminate one coupling cap in the phono circuit. I usually build a new line stage as well- one that has no feedback. I usually retain the original power transformer (if the mods don't fit in the original chassis then you might as well start from scratch...). We also have a tiny high voltage regulator that does amazing things for the sound.

There are very few preamps that will sound better than a PAS if it is properly modified. Its kinda fun to have a giant-killer in the PAS guise :)

Ralph, that sounds like it could be beyond my beginner abilities unless I had directions.I think that the impedance values are kind of weird, but I can live with it for now.Very sensitive volume pot.

I saw that there is a guy that offers new "Spice" designed boards that incorporate 3 tubes on each board. Interesting!

Regenesis and Dynaco Doctor both offer new boards.
Are these updated circuits/caps or are they just replacements?

e

Emorrisiv, some are replacements, others are updates of one sort or another.

Since I don't like the unit to grow into multiple chassis, I keep the original power transformer and supply. That means that the line stage I have for it has to not draw more power than the original, which is important due to the limitations of the transformer.

If I were you I would start with simple mods and see how things sound. The nice thing about the PAS used to be that they are very simple, inexpensive and there were a lot of them. Nowdays they have gotten more rare, but they are still very easy to modify and I'm pretty sure its the most-upgraded/most-updated preamp ever made.