Having fun with a super clean Dyna PAS-3X tube preamp.

avahifi · « **on:** 16 Feb 2009, 05:25 pm »

Recently I had a local client simply give me an old, not used for many years, original Dyna PAS-3X vacuum tube preamp. The piece is in immaculate original condition, no faceplate wear, latest series machined gold knobs, no scratches in the cover, no broken AC jacks, as nice as I have seen in a long time.

So - - - since I no longer had a Super Pas Three here I had Matt (my great assistant) build it up into a Super Pas Three, with our complete board set and jack set. His rebuild work came out great and we listened for it for several days and then I had another thought. What if I could make it a lot better yet?

Years ago we offered an option for the Super Pas Three, solid state buffers to improve the linearity of the unit. They worked very well, improving dynamic range, transparency, and bass response, but had a drawback of sounding a tiny bit "solid state" of the very top end. Some of our clients liked the buffers a lot, others, not at all. This option was discontinued years ago.

But, now I have designed a day and night better buffer circuit, used as the Tape Buffer option in all of our new preampifiers, based upon Insight technology. So, what if I added Insight output buffers to the new Super Pas Three?

This morning we got it up and running and it sounds so nice (the "solid state" is all gone, the musicality, dynamics, and range greatly improved) that I am hereby offering it as a normal production option again, factory wired only, at $250 installed in a Super Pas Three. Sorry, we can't offer it as a do it yourself kit. The option is available for the line circuits only, no room for phono buffers too and that would double the price. However phono performance is improved as that circuit is benefited by the line circuit it feeds into.

So, what do you guys think? Finally we can offer a really good upgrade to all those Super Pas Three preamps out there.

Regards,

Frank Van Alstine

TjMV3 · « **Reply #1 on:** 16 Feb 2009, 05:49 pm »

Frank,

I've recently purchased a Van Alstine Super Pas 4i SL (hasn't arrived here, yet).

Would any of these upgrades apply to the Super Pas 4i SL?

avahifi · « **Reply #2 on:** 16 Feb 2009, 06:52 pm »

Yes they would. In your case we would not have to install new boards, just upgrade your existing mother board, and the upgrade would be done to both the line and the phono circuits. The cost is $300 for this. It is a major upgrade.

Regards,

Frank Van Alstine

rcag_ils · « **Reply #3 on:** 16 Feb 2009, 09:02 pm »

Frank, I thought the Pas 4i upgrade was $399.00.

Tom Alverson · « **Reply #4 on:** 16 Feb 2009, 10:54 pm »

Sounds like a great idea, especially since there are probably a ton of Super PAS Three preamps out there that could benefit. After this mod, would the performance be about the same as the PAS4i with the latest buffer update? Also, would you rate it as better than my ancient Fet-Valve preamp (in PAT5 chassis, with the original FET-Valve circuits)?

Tom

boycephoto · « **Reply #5 on:** 16 Feb 2009, 11:10 pm »

I am glad you have having fun with your Super PAS 3. It is nice to see new technology going into older yet still viable equipment.

So in your opinion...

what will be the best bang for the upgrade buck, putting the new buffers in my Super PAS 3 or updating my OmegaStar EC to a Insight? Please tell my why. Driving either my Ultimate 70 or OmegaStar EX 440H.

Thanks
Dave

rlee8394 · « **Reply #6 on:** 17 Feb 2009, 06:40 pm »

Frank,
I have a few questions on the new buffer for the Super Pas 3.
1) How does the unregulated Super Pas 3/Insight buffer compare to the unbuffered/regulated T8?
2) How would it compare to my '93 Fet-Valve Preamp?
3) Will there be an option/redesign of the T8 series equipment (Preamp, Phase Inverter, DAC) to include the new Insight buffer much the same way the old Super Pas 4i/T6 series did?

Thanks,
Ron

avahifi · « **Reply #7 on:** 17 Feb 2009, 07:00 pm »

Answering questions I hope.

The T8 is still better than the Super Pas Three with Insight buffers for two reasons. First the T8 uses the much "stronger" 6N1P tube. Second the regulated power supplies as used in the T8 make a substantial performance increase in tube stuff. These more than make up for the advantages of the buffer, which is there to "help" the tube, but can't do more than that.

I still would prefer the 93 Fet Valve preamp, assuming it was in great working order with good tubes.

No redesign planned for the Transcendence series vacuum tube equipment at all. They are there, after all, for folks that want pure vacuum tube equipment, and adding buffers would make them "impure".

The buffer improvements to the older equipment is very useful as reasonably cost effective to make a major bump up in performance of these units without resorting to the much more expensive option of specially designed new boards and circuits just for those now out of production chassis designs. That money (new boards and circuits just for old units) would be better spent on our new equipment.

Answering boycephoto's question; the Insight upgrade to your OmegaStar EC will still provide you with the best sound possible at a reasonable price.

Tom, regarding the comparison with the Super Pas 4i, that unit still is better than the Super Pas Three with Insight buffers because the 4i uses a better choice of tubes for line operation, the 12AT7. This tube has better current drive. In addition the 4i has a better power supply. The SP3 is limited by the original Dyna power transformer which does not have the current capacity to run 12AT7 tubes or to operate the tubes at higher plate voltages.

The Insight buffers make the Super Pas Three a much nicer preamp overall, with better dynamics, bass, range, and overall musicality than the unbuffered version. Its there because we can do it at a rational price and make your system work better. Our clients have asked for a SP3 upgrade for years, and now here it is.

Oh by the way the price is $399, sometimes I get confused in my doddering old age.

Best regards,

Frank Van Alstine

TjMV3 · « **Reply #8 on:** 17 Feb 2009, 07:32 pm »

Frank,

the owner of the Van Alstine Super Pas 4i SL I bought, claims it uses two 12AX7 in the phono and two 12AX7 in the line stage.

I see that you said the Super Pas 4i uses the 12AT7.

Did you ever make Super Pas 4i that was all 12AX7? Or is he mistaken?

I believe the seriel number is: 000700

Tom Alverson · « **Reply #9 on:** 18 Feb 2009, 03:05 am »

Quote from: avahifi on 17 Feb 2009, 07:00 pm

Tom, regarding the comparison with the Super Pas 4i, that unit still is better than the Super Pas Three with Insight buffers because the 4i uses a better choice of tubes for line operation, the 12AT7. This tube has better current drive. In addition the 4i has a better power supply. The SP3 is limited by the original Dyna power transformer which does not have the current capacity to run 12AT7 tubes or to operate the tubes at higher plate voltages.

I knew that the line stages have progressed from 12AX7 to 12AT7 and now to the 6N1P, but did not realize that the power transformer was the limiting factor in the PAS-3 (preventing the 12AT7 "upgrade"). I don't know if the sonic improvement from the 12AT7 would make it worthwhile to replace the transformer, but I did notice that the new replacement transformers sold by Triode Electronics brag about beefed up specs (15mA from the HV winding). That transformer sells for $33 but I don't know what shipping costs:

http://store.triodestore.com/pa2powtrandy.html

Also, someone in Hong Kong is selling a toroid replacement for $60 that claims 25mA capacity from the HV winding. Either of these is much more than the 5mA that the stock PAS3 draws, but I have no idea what the 12AT7 "upgrade" would require. This toroid is for sale on Ebay:

http://cgi.ebay.com/High-Amp-Power-Transformer-for-Dynaco-PAS-2-&-3-Preamps_W0QQitemZ270334873313QQcmdZViewItemQQimsxZ20090125?IMSfp=TL090125165004r9933

Tom

dB Cooper · « **Reply #10 on:** 18 Feb 2009, 03:21 am »

I had a 4i, which I built from a kit, and IIRC it already had SS line buffer circuits. Are these bypassed in the new upgrade you are talking about, Frank, or are the circuits on the motherboard retrofitted with the new Insight components?

(TjMV3: My 4i was 12AX7 in both the phono and line sections. Dunno when the 12AT7 change was introduced.)

Good to see AVA still breathing life into old "obsolete" "dinosaurs" like the PAS3. One of these days (=recession over) I should give Frank a call and see what he could do with the venerable AVA SCA-80 MOSFET Control Amp (known to my friends as "Old Faithful") that I cannot bear to part with.

JerryM · « **Reply #11 on:** 18 Feb 2009, 04:35 am »

Quote from: rlee8394 on 17 Feb 2009, 06:40 pm

Frank,
3) Will there be an option/redesign of the T8 series equipment (Preamp, Phase Inverter, DAC) to include the new Insight buffer much the same way the old Super Pas 4i/T6 series did?

Thanks,
Ron

Is there a T8 Inverter Bridge?

Jerry

TjMV3 · « **Reply #12 on:** 18 Feb 2009, 05:04 am »

Thanks DB!!

martyo · « **Reply #13 on:** 18 Feb 2009, 09:44 am »

The Transcendence 5 has the 12AT7's.

rcag_ils · « **Reply #14 on:** 18 Feb 2009, 10:34 am »

Super Pas4i has 4 12AX7 tubes.

Quote

One of these days (=recession over) I should give Frank a call and see what he could do with the venerable AVA SCA-80 MOSFET Control Amp (known to my friends as "Old Faithful") that I cannot bear to part with.

Recession over? It will be here for a very long time, I am afraid. I am wondering when will Obama "fill my gas tank and pay my mortgage." Quote from his teenie bopper supporters during the election.

martyo · « **Reply #15 on:** 18 Feb 2009, 01:10 pm »

Quote

Recession over? It will be here for a very long time, I am afraid. I am wondering when will Obama "fill my gas tank and pay my mortgage." Quote from his teenie bopper supporters during the election.

What does that have to do with "Re: Having fun with a super clean Dyna PAS-3X tube preamp"?

This place is a sanctuary from all that crap, it's about music and hi-fi's.

martyo · « **Reply #16 on:** 18 Feb 2009, 01:12 pm »

Sorry Frank for my outburst.

oneinthepipe · « **Reply #17 on:** 18 Feb 2009, 03:34 pm »

Quote from: martyo on 18 Feb 2009, 01:12 pm

Sorry Frank for my outburst.

What outburst?

martyo · « **Reply #18 on:** 18 Feb 2009, 04:05 pm »

Quote from: oneinthepipe on 18 Feb 2009, 03:34 pm

Quote from: martyo on 18 Feb 2009, 01:12 pm
Sorry Frank for my outburst.

What outburst?

Later I remembered I could edit my original post, I deleted part of it.

rcag_ils · « **Reply #19 on:** 18 Feb 2009, 11:35 pm »

sorry for making fun of the recession. I am sure it hits home for a lot of people, just want to find some humor out of a bad situation.