Dynaco PAS 2 vs. PAS3x

[vinyl fiend]

What are your opinions between a PAS 2 and a PAS 3x pre-amp? Does either one sound any better? I plan on selling one, but cosmetically, the bronze/brown PAS2 matches my ST-35 better. However, if the PAS 3x is a better performer, I would have to reconsider. :scratch2:

 

[gadget73]

The only difference is the faceplate and the tone controls. THe PAS2 is brass, the 3 and 3X are aluminum. SOmething particular to the 3X are the center-off tone controls that lift it out of circuit when set to "flat". Other than that, its the same thing under the hood. If you're really feeling some kind of way about it, you can swap the faceplates and keep the brass one on the 3X if you want to be able to kick the tone controls out.

 

[s-petersen]

The 3X has a tone control defeat built in the center position of the controls and a dc blocking cap ,otherwise they are supposed to be the same IIRC
Let your ears be the judge.you can always paint the cage of the ST35 black which would match the 3x better.

 

[DC]

Yes, those are the only differences and I would simply switch the faceplates, too. And then you could call it a PAS-2X.

 

[peterh]

What are your opinions between a PAS 2 and a PAS 3x pre-amp? Does either one sound any better? I plan on selling one, but cosmetically, the bronze/brown PAS2 matches my ST-35 better. However, if the PAS 3x is a better performer, I would have to reconsider. :scratch2:

You have the answer! Listen to them and figure out which one sounds best.
And yes, please tell us what your choice is .

 

[gadget73]

Those specific tone controls are rather hard to find though. It was a particular design that lifted the wiper. Not exactly a common control.

 

[peterh]

Thank you, quite correct. I should have said that he could remove his tone controls (if he is not too attached to them), and the resultant circuit could emulate Dynaco's X-mod with the tone controls centered even without any pots. Should be an improvement in sound quality, too.

If the tonecontrols are bypassed, isn't pas2 and pas3x equivalent then ?

 

[vinyl fiend]

Thanks dudes. I like the look of the PAS 2. I'll probably keep that one in the long run.

 

[audioregen]

If the tonecontrols are bypassed, isn't pas2 and pas3x equivalent then ?

Not quite. The resistor values on the blend switch were also changed on the 3X. Not that it matters to you, especially if you don't use the blend feature.

 

[peterh]

One would think so, all things being equal. But, I’m thinking it depends on the condition of the pots after so long, on the integrity of the internal parts of the bass and treble pots, with the bass pot needing to short and the treble pot needing to open, in both cases cleanly. But, how exactly did they do that when they were brand new, and what might have deteriorated over the decades? In any case, I have considered that just pulling all the parts related to the tone controls out, installing jumpers in the right places, etc., might possibly yield a cleaner result. Just wanted to offer it as an option.

"But" ? Elimination of tone controls means bypass the potentiometers ? Then
there woudl be no differences between pas2 and pas3x ? Or is there something
i do not understand?

 

[tygr]

I'm about to bring my own PAS 3x up to date with the "Z-mods" boards and updated power supply board (parts are due to arrive on Monday). This will eliminate the tone controls completely and I'm hoping for a much better SQ from the old workhorse. We don't need no stinkin' tone controls.

 

[peterh]

I'm sorry, not sure I understand your question. In terms of the tone controls, "bypassing" a.k.a. "removing" the tone controls in PAS2/3 should yield the same results as centering the tone controls in PAS2X/3X. But, I was raising the point that removing the tone control circuit even in PAS 2X/3X might still be a good idea, even though they are supposedly "out of circuit" when the pots are centered. Sorry if I created any confusion – please let me know if I can clarify further.

The original question was "which one to keep".
And if the intention is to remove the tonecontrols, then anyone will do equally well then, i assume from the answer.
Personally i keep the tonecontrols for the reason of keeping the music as enjoyable as possible even when recordings are less then good. Ymmw

 

[bronco]

If you are planning on doing any mods, or even just removing the tone controls, keep the PAS2. The stock PAS3X is rarer, more collectible, and will fetch more money when you sell it.

 

[vinyl fiend]

They are both in excellent stock condition. I'll do the mods to make an improvement, but leave the tone controls alone. I think its the power supply mod that is most crucial? also, updated RCA connectors is pretty practical.

 

[peterh]

Myself fixed the high output impedance that plagues both the tape output and the
main output by bu adding an external unit that contains 4 cathode followers.
In the same external box i added a power sequencer to make shure that the
power amp and preamp is powered on and off in the right order and preventing
power cycling(s) ( as per recommendation of d. gillespie)
I have it documented "online" if anyone is interested.

 

[VBB]

Myself fixed the high output impedance that plagues both the tape output and the
main output by bu adding an external unit that contains 4 cathode followers.
In the same external box i added a power sequencer to make shure that the
power amp and preamp is powered on and off in the right order and preventing
power cycling(s) ( as per recommendation of d. gillespie)
I have it documented "online" if anyone is interested.

I know this is old, but do you still have it documented?

 

[peterh]

I know this is old, but do you still have it documented?

Yes.
See http://n.manet.nu/fm1/index.html

 

[VBB]

Thank you!