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Preamp DynaKit PAS-3

JosephL

JosephL

Member
My son has his grandfather's DynaKit 70 and preamp with new caps. Front end is a restored Thorens TD 150 mk2. Vintage and sweet.
He wants to use the preamp DynaKit PAS-3 and run a second system. My suggestion was to use preamp tape out and plug into another's receiver CD(or tape in) input. Realizing the DynaKit tape out would have been for a reel-to-reel, I am assuming it was a standard 2 volt signal.
Any potential problems with using the preamp DynaKit PAS-3 to drive the second system?
Thanks,
Joseph
 
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JosephL said:
My son... wants to use the preamp DynaKit PAS-3 and run a second system. My suggestion was to use preamp tape out and plug into another's receiver CD(or tape in) input.
Click to expand...

I could be misinterpreting your initial post, does he want to run the PAS-3 separately with a receiver or in conjunction with the ST-70 controlling both?

What is the receiver? does it have Pre-out/Main-in?
 
Use the DynaKit 70 if he turns it on to drive his main speakers. Plug the DynaKit PAS 3 tape out into a plain everyday Yamaha receiver CD input, using the Yamaha as the power and volume for his second pair of speakers. So he can run either or both speakers, using the DynaKit PAS 3 to process the Thorens for both systems.
Thanks,
Joseph
 
You should be aware that the PAS phono section will be very sensitive to loading at the tape out jacks. It was meant to drive a high impedance load such as would be presented by a tube type RR deck. Connection to SS devices may result in excess loading and loss of bass response.
 
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audioregen said:
You should be aware that the PAS phono section will be very sensitive to loading at the tape out jacks. It was meant to drive a high impedance load such as would be presented by a tube type RR deck. Connection to SS devices may result in excess loading and loss of bass response.
Click to expand...
Second. It would work if a buffer is inserted between the preamp and the Yamaha.
 
Instead of the Yamaha solid state, what if he used a the tube hybrid integrated amp? One of the $150 seen on Parts Express, Amazon, eBay, etc? Would that buffer?
Thanks,
Joseph
 
It would depend upon the input impedance of the particular amplifier. FYI here's a link to a technical article covering the PAS phono stage. The section on loading effects begins part way down page 9. You would want the input impedance of any device connected to the tape out jacks to be well above 100K ohms.
http://audioregenesis.com/documents/PAS_Phono.pdf
 
I wound use one of these :
Dynaco PAS Preamp Impedance Matching Module Buffer (available from sites such as eBay)

( although buffering tape out instead of line out)

Sorry about the link. Won't repeat!
 
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Couldn't you get around the impedance issue by simply rewiring the tape output jacks as a second set of main outs?
 
daveshel said:
Couldn't you get around the impedance issue by simply rewiring the tape output jacks as a second set of main outs?
Click to expand...
No. Have a look at the schematics then you see that there is no power for more tubes, and the existing tubes are fully engaged .
The main out is also limited in drive capacity, that's the reason the buffer board was made.
 
Yes and no, it would eliminate loading issues on the phono pre, but it could cause loading problems on the line stage. It wouldn't require any more power to simply parallel the existing outputs but I don't think it would fix anything either.

also the output would be volume controlled which may or may not be desirable.

tape out probably wants a bit of gain anyway, the tape out is basically straight off the phono pre and I don't think that gets anywhere near 2v of output. Might be closer to a half volt? Might be less than that, I've never actually measured it.
 
Trying to keep it simple. Parts Express has three hybrid tube integrated. All have input impedence of 47K ohms minimal.
Will work? Won't? Maybe?
Thanks
Joseph
 
Ok, I was going with audioregen's previous post with 100K ohm loading needed.
If we can't do it simple, he'll just have to stay with DynaKit tubes and the Thorens 150 mk2 and one pair of speakers.
Thanks
Joseph
 
audioregen said:
It would depend upon the input impedance of the particular amplifier. FYI here's a link to a technical article covering the PAS phono stage. The section on loading effects begins part way down page 9. You would want the input impedance of any device connected to the tape out jacks to be well above 100K ohms.
http://audioregenesis.com/documents/PAS_Phono.pdf
Click to expand...

There are two different sellers on eBay who have impedance matching add-on boards for the PAS3. I've been meaning to post a thread to see if any of the Dynaco gurus had an opinion about them.
 
if you're up for some light DIY you could just smash together a simple op-amp buffer run right off the filament supply. Thats +/- 12v which is plenty enough. A dual op-amp wired as a zero gain buffer between the output of the line stage and the output jacks would let it drive anything you could want. It wouldn't pull enough current to bother anything, but if there was really any concern sub the pilot light for an LED and that will free up more than enough.
 
Sam Cogley said:
There are two different sellers on eBay who have impedance matching add-on boards for the PAS3. I've been meaning to post a thread to see if any of the Dynaco gurus had an opinion about them.
Click to expand...
I have installed one of these. To the line output, but buffering tape out instead is just a matter
of choosing wires.
I don't thing mounting allows 2 of these boards ( at least not simple )
 
peterh said:
I have installed one of these. To the line output, but buffering tape out instead is just a matter
of choosing wires.
I don't thing mounting allows 2 of these boards ( at least not simple )
Click to expand...

What did you think of it, and which one did you use? The black US version, or the yellow/tan Hong Kong version? I've thought about getting one, as having the PAS3's notoriously picky impedance matching neutralized to use it with a wider variety of amplifiers would be quite nice.
 
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