Dynaco PAS 2 value and difference to PAS 3?


I have an opportunity to buy a Dynaco PAS 2 but wonder how much it is worth. It is stock and works fine. Just looking for a rough estimate.

Also what is the difference between it and the PAS 3(X)?

thanks for any information

Phil
128x128philjolet

Showing 4 responses by atmasphere

I've been doing mods on the PAS preamps for 30 years. There is **plenty** of reason to bypass the tone controls! Even if set flat, the stock line stage lacks bandwidth and resolution. However the line stage circuit can be seriously upgraded such that the unit will easily keep up with many modern high end preamps.

The phono section is only good for high output MM cartridges, but it too responds readily to upgrade. If you have no plans of using it for tape, the EQ components can be moved to the PCB and the middle wafer on the input selector swich can be eliminated. There are also improved EQ values, and one of the coupling caps at the output of the phono can be easily eliminated too.

They are, IOW, great preamps if you plan to tinker or update. In stock form they are OK but nothing special. The 3 and 3x look a little nicer and that is the only reason to pay any more for them. The filter caps, both high voltage and filament, should be replaced regardless of your plans. I usually replace the filament rectifiers as well- the old selinium units are nasty.

Have fun!
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!
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 :)
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.