On the Dynaco OEM PAS Series

What you get in any form:

a) A pretty decent stereo audio pre-amp.
b) A better-than-average (then and now) phono pre-amp.
c) A better than average (then and now) NAB head-amp - this has vanishingly few applications these days, but the position may be modified for line-level or RIAA inputs.. Further, some very few magnetic phono cartridges do have a flat output - compatible with NAB.
d) A Stereo/Blend/Mono switch that (at the time) allowed the playing of exaggerated stereo recordings. Today, it allows soundstage adjustments that a typical modern pre-amp cannot achieve, meaning that it can adjust to room issues.
e) An effective and meaningful Loudness Contour switch - in my office, it allows me to hear bass and treble without having to blast.
f) A just-about-right high-pass filter - I keep a number of re-mastered vintage recordings - this helps with the inherent hiss.
g) Just like NASA, all parts, pieces, jacks, controls, and switches supplied by the lowest bidder. See "care and feeding".

What you get with the PAS-3X (last in the line, made into ~1989 or so):
a) Compatibility with most solid-state amps. And, may be matched as needed to any solid-state amp with further small changes.
b) Null-center tone controls.

Meaning that the newest of these beasts out there is nearly 30 years old. The oldest is nearly 60. But:

a) With care and proper maintenance, these beasts are as safe and reliable as the day they rolled out of the factory (term used very loosely).
b) At the right price (well under $400), they are a bargain *when fully maintained*.
c) There are any number of after-market tweaks, upgrades, revisions and variations such that the core beast may be 'made over' to various degrees.

Which, at the end of the process will give a reliable pre-amp with a high level of flexibility and multiple options all in one box.

For less than $100 (in addition to the cost of the pre-amp), and about an hour in time one may achieve a) - g) + a) as listed above.

Yes, they have their issues. 99-44/100ths of which are due to lack of care and feeding over the years.  

Sometimes, things just work.

"Sometimes, things just work."

But rarely, a PAS3.

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Assembled mine in the spring of 1974 from a kit. Will send on to my grandson when he is old enough for it.

Many things were wrong with it from the beginning. Tracked down to mostly bad controls. During the maintenance process the volume control, the balance control and one of the bass controls were replaced. During the rebuild process all the capacitors and a few of the resistors were replaced. It still matches the original schematic.

Sounds better now than it did at day 1. Not used much but they can be worth fixing if you can find the correct value parts. Keep them working.

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After 40 years in the Audio  Hobby an biz...Owning just about every speaker made...ESL Speakers have wone the Day...Yes I have, Apogee ribbon, Magnepan, an some old Tyler pistons around....but the Acoustat 2+2,1+1s...An the Martin Logan CLS ,like new ESL panels are what I use the most today...The thing the Stock Pas 1,2,3,3X give me is the Tone Control...
It a Big If...But my CJ PV 2ar-or 5 or my old Krell KSL had these Controls...thay may rule my world...but with new Caps,Stock Pas is a Winner!...Ever the old Stock pots sound great...

The old Pas just let me get the Best Sound in my room to day.... Others Say ...You can do better...well live with a None for giving speaker like the first Cls ...that can be driven to full out put with a Stock ST70....in a 18'X 25' room with just one chair in it...Thay may feel diff...
I say yes, the Preamp is the key...the front end as we say....get it right... it Well-Can make the hold setup.... good are bad....
An at the Old Dyna Pas tube preamps price...its a lot of fun...


Happy Holidays to All...




Thanks for the site Bob......

Peter W. wrote:What you get in any form:

a) A pretty decent stereo audio pre-amp.
b) A better-than-average (then and now) phono pre-amp.
c) A better than average (then and now) NAB head-amp - this has vanishingly few applications these days, but the position may be modified for line-level or RIAA inputs.. Further, some very few magnetic phono cartridges do have a flat output - compatible with NAB.
d) A Stereo/Blend/Mono switch that (at the time) allowed the playing of exaggerated stereo recordings. Today, it allows soundstage adjustments that a typical modern pre-amp cannot achieve, meaning that it can adjust to room issues.
e) An effective and meaningful Loudness Contour switch - in my office, it allows me to hear bass and treble without having to blast.
f) A just-about-right high-pass filter - I keep a number of re-mastered vintage recordings - this helps with the inherent hiss.
g) Just like NASA, all parts, pieces, jacks, controls, and switches supplied by the lowest bidder. See "care and feeding".

What you get with the PAS-3X (last in the line, made into ~1989 or so):
a) Compatibility with most solid-state amps. And, may be matched as needed to any solid-state amp with further small changes.
b) Null-center tone controls.

I agree! I own a 3x and sometimes think I am the only one who actually values having tone controls, loudness switch, High cut switch, and yes, even the blend control. Well, I guess there are at least a few of us

One thing I do wish is that the tone controls were dual element pots so I didn't have to adjust L and R separately, but those controls are so specialized as is. Maybe they couldn't stack them?

I believe that the separate bass/treble controls was a deliberate choice rather than a cost or design constraint, as the later Dynaco solid-state controls were also null-center and stacked.

I very much appreciate the Loudness Switch - as my little system runs about 9.5 hours per day in the office at low volume - without that option, I would not get much bass or treble.

CD changer to PAS 3X to ST 35 to AR Athena Sub/Sat.