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    Dynaco PAS preamps

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    MontanaWay

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    Dynaco PAS preamps

    Post by MontanaWay on Tue Feb 11, 2014 5:08 pm

    got a chance of getting hold of an old Dynaco PAS preamp, probably will need to refurbish it, my question is, what are your thoughts, are they/were they good, your thoughts would be appreciated.

    Bob Latino
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    Re: Dynaco PAS preamps

    Post by Bob Latino on Tue Feb 11, 2014 10:43 pm

    Hi,

     Everyone on the forum knows that I have a great deal of affection for Dynaco tube gear - BUT - IMHO from the standpoint of best sound quality, A Dynaco PAS-2 or PAS-3 preamp needs heavy modification to really sound as good as modern preamps. It is probably not financially feasible to sink money into an older PAS preamp to bring the preamp up to modern preamp standards. Years ago I found out that the PAS preamps "held back" the Dynaco AMPS from sounding their best. In stock form (again IMHO) the PAS preamps are slow and thick sounding. In about 1980 an audiophile friend of mine brought over his new Audionics BT-2 preamp. This was a quality (for it's time) solid state preamp made in Oregon. We swapped out my PAS-3 preamp for the Audionics preamp for a listening session. Wow .. what a difference!. The Audionics had a much better "jump factor" on musical peaks that the PAS-3 could not reproduce. The phono stage on the BT-2 was much better. I had never heard music out of my ST-70 like that before .. I wanted a BT-2 bad but could not afford it at the time ..

    You have to sink a lot of $$$ into a PAS preamp to really get it to sound good. Bypass the tone controls, beef up the power supply etc. Personally I don't think it's worth the effort. Of course if you want the look of a vintage sound system or you are buying the PAS for its historical value then do it. Just don't do it if your intent is to get the best sound out of your music system .. If you want really good sound at a reasonable price, consider one of Roy's SP preamp kits ...

    Bob

    MontanaWay

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    Re: Dynaco PAS preamps

    Post by MontanaWay on Tue Feb 11, 2014 11:03 pm

    thanks Bob, I appreciate your input. Like a lot of other gear, there's so much tube based gear out there, old and new, and trying to get one's head around it is not easy.
    I've been reading up on the PAS, both good and bad reviews and opinions.
    But I think you're right, I'll be better of with an SP9 I think, I should be able to get one in April.
    Now, the turntable I have has a built in preamp, which can be switched in and out.
    With the SP9, I should be able to connect the turntable to the AUX input and use it with its preamp switched on, yes?

    daveshel

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    Re: Dynaco PAS preamps

    Post by daveshel on Wed Feb 12, 2014 12:25 am

    You're likely to find that your built-in phono preamp isn't in the same league as the SP9 or its siblings - it may be more designed for USB. You might be better off getting a model that has the phono built in from the start, as it is cheaper that way than getting one on its own chassis.

    MontanaWay

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    Re: Dynaco PAS preamps

    Post by MontanaWay on Wed Feb 12, 2014 10:52 am

    daveshel wrote:You're likely to find that your built-in phono preamp isn't in the same league as the SP9 or its siblings - it may be more designed for USB. You might be better off getting a model that has the phono built in from the start, as it is cheaper that way than getting one on its own chassis.

    you're right, it is, when I get the PS9 I'll get the phono preamp as well and build that into it.

    daveshel

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    Re: Dynaco PAS preamps

    Post by daveshel on Wed Feb 12, 2014 11:18 am

    One of the advantages of using the PAS chassis is that it has room for the phono board. I got one several months ago for about $235, thinking I'd save on the chassis and associated parts. When I got the unit, the feet were missing and the front panel wasn't in very good shape. Upon further analysis, I saw that I could have bought the new chassis, cover and front panel for $233 plus shipping, so I hadn't really saved anything. Sure, I got the original historical look and the chance to play with it - I removed the tone controls and switches, had some fun, got some experience. I still plan to gut it and redo it with Roy's best boards (a $500+ expenditure I keep putting off) but if I had to do it over again I think I'd go straight for one of Roy's kits.

    (The $500+ included power supply board, 21-step volume control, balance control, selector switch, RCA jacks, Aikido line stage, PH-10 phono board, tubes and pilot lamp, but not power cord or slide switches.)

    MontanaWay

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    Re: Dynaco PAS preamps

    Post by MontanaWay on Wed Feb 12, 2014 1:21 pm

    yeah, the PAS is about $290, has not been used for about 35 years, so it will need some re work for sure, power supply might need upgrading etc., even though it would be fun to play with it, $ wise might be better off to go with a new PS9 & phono preamp.

    TN Allen

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    Re: Dynaco PAS preamps

    Post by TN Allen on Sun Feb 16, 2014 11:27 am

    I'll also recommend the SP9 rather than upgrading a PAS3X. I've done both, the PAS3X because it was a kit I assembled in 1969 and wanted to upgrade, the SP9 because I wasn't as happy with the upgraded PAS3X as I thought I'd be. This is not to say the PAS3X upgrade was not a significant improvement over the original, it's now a very nice preamp, however, the SP9 seems better, although, the new PAS3X has the phono board upgrade and the SP9 does not.




    StereoGaryo

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    Re: Dynaco PAS preamps

    Post by StereoGaryo on Wed Feb 19, 2014 6:59 pm

    The PAS-4 would be the exception.

    MontanaWay

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    Re: Dynaco PAS preamps

    Post by MontanaWay on Wed Feb 19, 2014 7:47 pm

    well I have opted for an old non working PAT4 (for the chassis), stripped the chassis and bought the SP9 & PH10 kits, details on a separate thread, below.

    http://dynacotubeaudio.forumotion.com/t2052-call-me-madcall-me-silly

    tubes4hifi
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    Re: Dynaco PAS preamps

    Post by tubes4hifi on Tue Feb 25, 2014 2:17 pm

    I agree 100% with Montana and TNAllen!   It's better to start fresh!   You can easily spend $500-1000 to upgrade a PAS, but for the same money (and selling your old PAS)
    you wind up with a better preamp.    I finally made that original post from years ago into a STICKY!
    And using an old PAT4 chassis is the least expensive way to go, find one for under $100.

    Roy - Tubes4HiFi

    MontanaWay

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    Re: Dynaco PAS preamps

    Post by MontanaWay on Tue Feb 25, 2014 2:46 pm

    the only problem now....D'OH!!!....is that the PAT4 chassis is too small!!??!!??!!....I cannot fit the SP9 & PH1 pcb's with the toroid in it!!!!!......anybody wanna buy a PAT4 chassis with drilled cover??  Razz

    SOOO.....I have now designed my own PS9 chassis, one where all the tubes will sit on top with the toroid AND including a pair of Nixie tube 'VU meters', got the VU meter kit from a guy in Germany.
    Gonna cost me a few bucks for the chassis...but what the heck...ya only live once!!
    Once I have the chassis etc., will start posting photo's.

    TN Allen

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    Re: Dynaco PAS preamps

    Post by TN Allen on Wed Feb 26, 2014 9:22 pm

    I didn't use a PAT4 chassis, rather, I tried something a bit different using the SP9 PCB kit. It's still a prototype, but so far, open, and with mixed knobs has less hum than the PAS 3X with Mr. Motram's upgrade phono and line amp PCBs. Which is to say, very little hum indeed. I don't know how I'd add a phono board, probably just make the chassis longer and keep the transformer under the Aluminum plate beneath the Corian.

    An alternative to using the phono board in the preamp might be to include a phono preamp as part of the turntable, but with tubes and a PS that might become a bit complicated.

    Here is a link to a Flickr image of the prototype:

    http://www.flickr.com/photos/68227271@N04/12804600814/

    MontanaWay

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    Re: Dynaco PAS preamps

    Post by MontanaWay on Wed Feb 26, 2014 9:36 pm

    I always liked the idea, and have owned over the years, what I call component audio systems.
    Power amp, separate preamp, equalizer, one per channel, cassette deck and phono player, the last system I had was neatly mounted in a 19" rack system, looked like one of the early industrial computers with all those knobs, switches, lights etc.
    This is just the beginning for me with tube audio equipment, I will be 'happy' with the ST-70 for a while, but I already know I will probably go down the M125 block, depending on the overall sound quality of the SP9 I'm building (no doubt it will be excellent), I'll probably hang on to that for the M125's and perhaps a separate phono amp in its own enclosure matching my custom SP9 chassis, but all that is at least 12-24 months away,.......then again..... Wink 

    I am also playing with the idea of getting a reel to reel tape deck again, I used to own a 4 track TEAC back in the 70's, was a great unit! Talk about going back to the old days!!!!!!

    by the way, were you trying to show a photo on your post?.....it is not showing

    MontanaWay

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    Re: Dynaco PAS preamps

    Post by MontanaWay on Wed Feb 26, 2014 9:38 pm

    TN Allen wrote:I didn't use a PAT4 chassis, rather, I tried something a bit different using the SP9 PCB kit. It's still a prototype, but so far, open, and with mixed knobs has less hum than the PAS 3X with Mr. Motram's upgrade phono and line amp PCBs. Which is to say, very little hum indeed. I don't know how I'd add a phono board, probably just make the chassis longer and keep the transformer under the Aluminum plate beneath the Corian.

    An alternative to using the phono board in the preamp might be to include a phono preamp as part of the turntable, but with tubes and a PS that might become a bit complicated.

    Here is a link to a Flickr image of the prototype:

    http://www.flickr.com/photos/68227271@N04/12804600814/

    now that is a neat look...kind of a 'modernist' look like your speakers....I like it!

    TN Allen

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    Re: Dynaco PAS preamps

    Post by TN Allen on Wed Feb 26, 2014 10:25 pm

    MontanaWay,

    That's a make-it-up-as-you-go aesthetic or design strategy, actually it's just bumbling along without much of a clue.

    We have a slow dial-up service and posting the photo link or any file of even moderate size is a challenge that requires a person not feel too victimized or vindictive, it took some perseverance.

    I think you probably can fit the SP9 board and transformer into the PAT 4 chassis. The phono board maybe not, but perhaps someone on the forum has worked out a solution to that problem.

    This is off-topic, but just now in Maine its cold, I'm tired of winter, and more of it's on the way. It's probably even worse in Montana, but that photo of you and that fish against that green stuff in the background reminds me we may eventually have spring and summer again, that it hasn't failed in millennia, and may not this year, though I'm not counting on it. It's a great picture!

    MontanaWay

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    Re: Dynaco PAS preamps

    Post by MontanaWay on Wed Feb 26, 2014 10:55 pm

    TN Allen,

    trust me I tried, there is no possible way to fit both PCB's and the toroid into an old PAT4 chassis.
    Its no problem, I paid $35 for the PAT4, so its not a great loss.
    The custom SP9 chassis I designed will look great, much better than the PAT4. I like the look of all the tubes sitting on top with the transformers, so thats how this one will be.

    We like the winter here, mind you, it is nothing like what I call the east coast winter, that wet damp cold. We are at 5600' here, the snow is powder dry, I mean REALLY dry, so it is easy to deal with, the air is extremely dry, sure it can be cold, but the average here in winter during the day is low 30's and at night low 20's, so its really not that bad. Yes we get real freezers, but not that often.
    We go cross country and snow shoeing in Yellowstone Park, just over an hour from here, it is awesome in winter, especially the snow covered bison in the snow hanging out close to the hot pools and geysers! When you pass them in a snow mobile, they look BIG!!!!

    Have a look here, I added some winter & summer photos from our area

    http://s1029.photobucket.com/user/MontanaWay/slideshow/Big%20Sky%20country%20Montana

    DynakitParts
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    Montana Photos

    Post by DynakitParts on Wed Feb 26, 2014 11:52 pm

    Montana...
    Beautiful photos....Makes me want to move out of New Jersey. In fact, I would think we had more snow this year than you did?

    I'm also a trout fisherman.....fly & spinner. Like TN said...I cannot wait till Spring and warmer (snow free) days.

    Regards,

    Kevin @ Dynakit

    MontanaWay

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    Re: Dynaco PAS preamps

    Post by MontanaWay on Thu Feb 27, 2014 11:39 am

    DynakitParts wrote:Montana...
                  Beautiful photos....Makes me want to move out of New Jersey. In fact, I would think we had more snow this year than you did?

    I'm also a trout fisherman.....fly & spinner. Like TN said...I cannot wait till Spring and warmer (snow free) days.

    Regards,

    Kevin @ Dynakit

    well us locals fish right through winter, ice & weather permitting, some great winter midge hatches in the afternoons!

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