Mallette Posted August 7, 2002 Share Posted August 7, 2002 Due to a bit of good fortune, I've obtained just enough cash to have Frank Van Alstine rebuild my ST-70. Not a minute too soon...the old HK Citation 12 is about to drive me nuts with SS sound. Franks's price is 589.00. I'm not going into the details here as they are available at http://www.avahifi.com if you are not familiar and wish to render an opinion. However, the work is extensive. As my preamp is an AVA Super PAS4i, this makes sense. Frank himself suggested I buy the kit and do it myself, but the savings are less than 200.00 and I want it done right the first time. Thoughts? Dave ------------------ David A. Mallett Come taste muh' Klipsch! This message has been edited by Mallett on 08-07-2002 at 10:23 AM Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted August 7, 2002 Share Posted August 7, 2002 From other reports I have heard good things about this kit/mod which goes about a different solution using Constant Current Source application. Before dropping $600 ducats on a Dynaco I would give serious thought to doing it yourself. This kit does away with the circuit board on top as well. I think it would be a good experience and Ron Welborne has been doing kits for YEARS and has a solid rep here. Here is some of the text: quote: NO! Not just another ST-70 driver mod. This circuit, designed for us by Alan Kimmel, uses a triode first stage operated in the ideal constant-current mode. This and other features enable this ST-70 to deliver "REAL MUSIC". In fact, in all my years of modification experience, this is the best ST-70 mod I have ever heard! It beats all others hands-down and now this circuit is available to you at a great price.Why modify the ST-70? The Dynaco ST-70 is probably the most popular tube amp ever built. However, by todays standards its sonic performance is somewhat mediocre. Its bass response is loose and the top-end lacks the detail required to make it a real contender. These deficiencies can be attributed to its less than adequate power supply filter capacitance and its simple but ineffective driver circuit. There are alot of ST-70 driver board mods out there but most have taken a classical approach to solving this amplifiers deficiencies. Alan Kimmels ST-70 modification incorporates an advanced constant-current technique using a 6U8A tube to operate the 5751 triode voltage gain stage in the most linear manner possible. In addition, the output of the 5751 is optimally coupled to the rest of the circuit and this coupling is such that the 5751 sees virtually no capacitance and no loading at all. The amount of negative feedback is modest, and is taken from the 8 ohm output tap which is more effective than taking it from the 16 ohm tap, as most do. This circuitry results in a superior level of detail in both the midrange and top-end. Next, the output tubes bias supply is regulated resulting in a constant bias point with minimum drift. And finally, over 500uF of capacitance is added to the main power supply circuit resulting in a much tighter bass response and lower distortion throughout the frequency spectrum. High quality parts are used throughout the design which is conveniently mounted on two circuit boards that fit snugly inside the existing chassis. The result is that this is not just another modification, but a true innovation that brings you closer to the music than you ever thought the ST-70 (and most other amps) could. http://www.welbornelabs.com/st70.htm Of course, you can totally ditch the amplifier and start anew but I think this represents an easier task or the first timer. FRankly, spending $600 on the Dynaco gives me a bit of pause as there are other amps that 600 would do nicely. A pair of EICO HF-35 or 50 monoblocks could be had for this price and you are getting a FAR better base to work with with much better output iron. kh ------------------ Phono Linn Sondek LP-12 Valhalla / Linn Basic Plus / Sumiko Blue Point CD Player Rega Planet Preamp Cary Audio SLP-70 w/Phono Modified Amplifier Welborne Labs 2A3 Moondog Monoblocks Cable DIYCable Superlative / Twisted Cross Connect Speaker 1977 Klipsch Cornwall I w/Alnico & Type B Crossover Links system one online / alternate components / Asylum Listing f>s> Quote Link to comment Share on other sites More sharing options...
Marvel Posted August 7, 2002 Share Posted August 7, 2002 If you want to spend that kind of money, check out the Sound Values NEW model of the ST-70. Very cool! http://www.soundvalves.com/vta70i.html Later, Marvel Quote Link to comment Share on other sites More sharing options...
Mallette Posted August 7, 2002 Author Share Posted August 7, 2002 Unless my math is wrong, there is significant difference between 600.00 and 1100.00. Bill Barista brought a VT70i over at the last Klipsch Forum get together. Awesome. Love it, espcially the little blue bias lights. However, I doubt I'd hear much difference between it and the Van Alstine rebuild. Great musci so overwhelms me that I can't really distinguish between zip cord and 8 guage solid gold. The one working channel of the original sounded pretty darn good. Besides, I've been lugging this puppy around for 30 years...kind of attached, I guess. Dave Quote Link to comment Share on other sites More sharing options...
Colin Posted August 7, 2002 Share Posted August 7, 2002 Consider Bottlehead 2A3 Paramours compared to ST70s "Compared to the ST70, the results are as follows. Sub bass (below 35hZ) Larger, bigger, bloomyer, more defined. You cannot shake the house down with this combination, but you can hear all the bass notes in any recording. The super low frequencies are very audible and very musical. The ST70 must be turned up to about 5 to 10 watts to make these tones "happen" and the Paramours do them just fine. You can run out of juice, but remember what we have for power! The very finest amplifiers would be slightly tighter, but this is what I wish the ST70 could do. Bass: (35 to 140hZ) Harmonics of these bass sounds are very true. Bass drums have what I call just the right amount of dampning to sound real. Upper bass notes are authentic to the point of being able to tell what brand of bass guitar is being used. Bass ambience is detailed...could not ask for much better at 20 times the price... Must be heard. Mid bass/midrange140 to 2500hZ) Pretty special, because you hear it all. Extremely low volume sounds are not covered up, and anything in this range is smooth and easy to follow. Musical. No ringing, or harshness. Fast and clear. Treble: (2500 to 8K) Just like the Midbass/midrange...a seemless transition. Microdynamics causes you to hear new qualities to the familiar recordings that sounds complete. Excellent decay and attack. Thes sounds are slightly Darker than the ST70, but with much greater ambience. High Treble: (Above 8K) This area is very different from the ST70. The highs simply are not near as loud, but much more defined. The ST70 sounds "hot" here compared to the Paramours. The Highs are larger, without being as loud. You hear more detail! Much more comfortable. Love this sound." http://www.hometheaterhifi.com/volume_8_2/paramour-tube-amplifier-4-2001.html ------------------ Colin's Music System Cornwall 1s & Klipsch subs; lights out & tubes glowing! Quote Link to comment Share on other sites More sharing options...
mobile homeless Posted August 8, 2002 Share Posted August 8, 2002 ..and the Paramour is not even one of the best SET amps to boot. It's a cost effective design to meet a price point. I would pick it over the Zen, however. Hey Colin, have you heard the Paraglows? kh Quote Link to comment Share on other sites More sharing options...
Marvel Posted August 8, 2002 Share Posted August 8, 2002 Mallett, I agree that there is a price diff. Their price as a kit (which is supposed to be easy), isn't too bad. My own, as yet not upgraded, ST70, I purchased for $50, and have also had for over 25 years. I'll probably go with the Triode Electronics upgrades for it, and they are not very expensive. (Some would also say not as good as the AVA upgrades) I just don't want it to blow up form old caps that are dried out, etc. I bought mine from an acquaintance in the early '70s, and just this past Spring, started going over the schematic and instruction book. I found he had actually wired part of it wrong. I checked it, double, triple checked it. It really was wrong. I changed it, and is has made now difference in the sound. It needs a lot, and is too noisy to use right now. Marvel. Quote Link to comment Share on other sites More sharing options...
Mallette Posted August 8, 2002 Author Share Posted August 8, 2002 OK, so somebody has to come out of the woodworkd with something compelling, sexy, right up my alley, and in my price range. Those Paramours are excessively cool. Had no idea there was anything in the rarified world of SET at this price. Still, I've this ST-70 I've been hauling around... May get the rebuild, use it for awhile, then see if my mind wanders toward the SET world. I am sure I could get most of the money back on Ebay. Dave ------------------ David A. Mallett Come taste muh' Klipsch! This message has been edited by Mallett on 08-08-2002 at 10:34 AM Quote Link to comment Share on other sites More sharing options...
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