mmmalmberg

Marvel I believe you may be thinking of the PAT-4, made by Dynaco later on when they moved from tube to solid state. When Dynaco died, a company called something like Pancor bought the name and produced new gear, some of which seems to be highly regarded by those few who have it. The PAS-3 series II was another of their products. The PAS-4 is a hybrid tube/solid state preamp, and I guess they were sold up 'til 1999. -Mark M.

Colin, your PAS-3/II might be similar to the PAS-4, do you know anything about these? They're both by Pancor or whatever the company was that bought the Dynaco name. NOS, yes I've looked at the Mapletree you're selling and am quite curious about it. I sure wish there were a way to hear all these things... And so much equipment is either too old or too new to find good support etc., not that I know anything at all about Mapletree... Just for the sake of getting my search over I'm not far from flipping a coin for the Mapletree vs. a PAS4 that seems like it would might be a good thing as well. Both are a bit over my price point but I'm selling this and that so I might make it. C&S, I will be upgrading my PAS-3, but I have two ST70's right now and one preamp (the PAS) so I need to add one. One being my good system and one being the "family" system, I can either go for a bigger upgrade to the PAS and find a cheap but respectable pre for the family room, or I can just to a quick once-over-lightly on the PAS for the family setup and find something juicier for the "good" system. The 7T's I've seen run pretty expensive, and I'm not sure I want something old as I'm just about done having overhauled to ST70's and in the middle of my son's SCA-35 and the PAS still waiting its turn. But if I came across an affordable one in great shape that would be a nice option. Sunnysal, or others, within the names you mentioned, or others, what are particular models I might keep an eye out for? There's so many coming and going on ebay as well as audiogon, unfortunately it's not yard-sale season... Thanks for all these ideas everyone.. Mark M.

p.s. so how was the Paragon?

Well my price range really isn't worth talking about:) dismal one might say. But I'm trying to muster $450 or so. More than I've paid for anything else yet; I found a beautiful pair of Hereseys at an estate sale for about $90., plus $25. for new caps and they sound great. The ST70 I stole, decades ago, from my dad's basement and used it 'til the power tranny blew (it had 400 uF added to the p.s.) and so I gutted it and rewired it with new sockets and all - actually parts for that probably came out around $500. if I were to add everything up including the Kimber hookup wire. And I got my Thorens ttble for $25. at a big rummage sale... so I guess I've got to figure I've gotten away with murder so far and maybe I'll come up with a great deal on a preamp somewhere. But I need to know what the good preamps are to look for, in any case, whether for $100. or $1000., in case I find something underpriced. I.e. I don't want to steal an amp for $400. to find out it's not a good match for the ST70. OTOH I think the ST70 is somewhat flexible, it sounds not bad running off a pro audio mixer (actually better than my tired PAS3) so I'm open to solid state and/or hybrids. There's a PAS4 out there if I want it, hard to get a consensus on that preamp and I haven't heard one. Again I appreciate any and all thoughts or opinions! thanks Mark M.

Curious to know what anyone's favorite choices are of preamps with a Dynaco ST70. Mine is overhauled with a Curcio upgraded driver board and power supply, driving a pair of Heresey's. All thoughts/comments much appreciated - thanks. Mark M.

NOSValves - Which Curcio board were you using previously, that you mentioned in your original post? thanks Mark M.

Marvel - I've also run the ST70 off a mixer, a little Mackie 1202, actually sounded pretty good. Makes me curious about contemporary solid-state or hybrid preamps. There's a Van Alstine hybrid I'm considering, a PAS4i or something like that. Dean - I need phono if it's a real nice preamp and not if it's a real great deal like $100-200. This being because I'm setting up two systems, and the preamp could be for either. One's my "good" system and the other is my "family" system. Right now the good system is my fully rebuilt and modded ST70 with an unrestored PAS3 and the Klipsch Hereseys. The family system is my older ST70, slightly rebuilt and working fine, some KEF Coda 90's, and no preamp i.e. it's not up and running yet. In any case I don't think I'm going to spend over about $400. 'cause I'm laid off and I think there's enough stuff out there if I look long enough for the right thing (which is what I'm trying to identify...) I could use the PAS for the family system with only a minor bit of work, or I could do an extensive rebuild/mod and use it for my "good" system, which is the one needing the phono preamp.

Cool, we have just about the same amp. What are you using for a preamp? Also, guess what I have waiting for me in the garage..... a '68 Triumph GT6!

Marvel, which driver board did you use on your ST70? If it's a replacement with the same circuit as the original, then I think you could still call your amp a Dynaco, with an updated power supply. I've also fixed up a couple of ST70's recently. One, a later black-cage model, got one of Curcio's upgrade boards, but with fancier caps, and his power supply board, the same new power tranny you have, and all new sockets and wiring. The other, an early model, I just replaced the driver board, which was pretty rotten, with the original fiberglas one from the other ST70 that got swapped out for the Curcio board (I threw some new caps on that too). Both sound good, but the one with the Curcio driver board upgrade definitely has improved definition and dynamic response, and more extension of the frequency spectrum. I never rebuilt any amps before, but it was fun and rewarding. I then rebuilt the crossovers in the Heresey's (1968 models) which was much easier and even more rewarding (cheaper, easier and more obvious improvement) Now I'm looking for a good (great?) preamp for cheap for one of these. I have one PAS3, and two ST70's. And I'm using some Heresey's with the Curcio ST70, and some KEF Coda 90's with the other. So DLB945, do you think the Marantz you have is a really strong match to the ST70? Any other suggestions? Mark M.

Looking for a proven good match in a preamp for a nice freshly built, lightly modded ST70 and my Hereseys. Anyone else using an ST70 with Hereseys have suggestions? I don't have unlimited funds but at least I need to have some ideas to chase down... I'm not at all locked to a "vintage sound", i.e. a good hybrid might be a fine thing. I like great dynamics and extended response relative to what a stock PAS would offer. thanks for any thoughts. Mark M.

WWELLLL... I got the 2uF caps from Bob and rebuilt the networks as E's. Put a layer of 1" fiberglas on the left side and bottom, and part of the back of each. I left a printout of the "E" schematic folded under one of the xovers with an inch or so sticking out, for reference for the next rebuild if they make it that far. They are cured. Absolutely. They sound, I'm sure, like they're meant to. I never did measure the impedance of the woofers - if things hadn't sounded right that would have been one of my next steps. But now that my KEF's lack luster against the Heresey's, I'm happy. Thanks to everyone for your help, and thanks Bob for getting those caps out so quickly! I hope I don't get any cancer or whatever from the orange goop that leaked out of the old caps... BTW I'm driving these with a modded ST70 I just built, the output xformers and chrome chassis are the only original parts. Current weak link is the as yet un-rebuilt PAS-3. And our house was built in the early 60's, so it's all quite sympatico. Thanks again for the quick and useful responses. best, Mark M.

Well that seals the deal on woofer confusion, I'm sure I'd need to measure to know for sure at this point. I'll probably go one step at a time, get some new caps in there, test with different wirings of the crossover and see where that gets me, based on sound.. Clearly given the differences between the C and E networks there's some room to play.

I don't know the value of the inductor in the "C", which is marked 2133. Comparing to the Type E diagram, the woofer wiring is identical. It appears to me, if I'm not crazy, that the woofer is out of phase with the squawker and tweeter in the Type E configuration, and in phase in the C configuration. Bob I've done a sketch of the C schematic which I can email to you (or anyone...) if you're interested. The tweeter goes to the #2 tap through a 2.1uF cap. The squawker is going to tap #1, and the woofer goes through the inductor and a 1uF cap to tap #5. So in any case I'm figuring the woofer's probably not a problem, although I don't know if there's a correlation between the woofer impedance and the selection of cap values - ? Should I drive these units off the 16 ohm output of my amp? Why would the phasing be different between these two crossovers? thanks... Mark M.

I think I may need to try to measure the impedance with an ac load to be sure, given these variables. Would the later 8-ohm speakers have the same older logo on the back? Were the 16 and 8 ohm versions both refered to as K-22's? thanks... Mark M.

Well the DC resistance of the woofer voice coil is in the neighborhood of 6.5 ohms. So perhaps these are the 8-ohm woofers and just as suggested need the later xover in which case I'm feeling good... hope so.