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Dynaco PAT 4 Preamp

e_just

e_just

Active Member
Hello
I recently bought a Dynaco ST-150 and PAT 4 preamp. The phono stage of the PAT 4 is a little noisy so I was thinking about upgrading the power supply and replacing the old caps. I am beginning to wonder if it is worth the time and money to upgrade it. I was hoping that some of you guys can share your opinions and personal experiences of the PAT 4. I guess my main question would be, how good of a pre could the PAT 4 be after a complete overhaul?
Thanks guys!:D

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What kind of noise? If it is hum(60HZ) then there is a grounding problem or are you using a moving coil type phono cart.(very low output). So what kind of turntable/cart combo are you using?
 
If it is 60Hz hum, p/s caps may help fix the problem or it could be a grounding problem. If it is just excessive hiss, I think it may be "characteristics" of the particular transistors.

I also have a PAT-4/ST-150 combo that I use in my living room. The amp I got locally from a technician who upgraded a few parts internally, hand-picking the quietest components from a source of many. The pre-amp came from a guy in San Fransisco who also hand-picked quieter transistors (and re-capped the p/s). Together they are unusually quiet.

I overpaid for both and probably wouldn't go that path again. However, I have them and I enjoy them and I probably won't get rid of them anytime soon. :) It might be worth your time to try to get these to be where you want them. Your PAT-4 looks cleaner than mine! (By the way, there is a cool mod that will allow you to use the "special" input as another phono input so you can run two turntables with no cable swapping. It is in the manual, if you have one.)
 
Thanks for the input guys! I am currently using a Technics 1100A TT / Shure V15 IV cart. I am very familiar with ground hum and that is not the problem. The Pat 4 is just a little more hissey than I would like.
 
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