I bought a stock-looking used Dynaco ST-70 that was dirty and had one bad tube. I selected the amp because I wanted to try tubes per the advice of this board and a friend of mine had restored about 8 Dynaco ST70's and said he would do one for me for the cost of the parts...he even did the "elbow greese" work and only charged me for the cleaning materials. I will return the favor which is appreciated.
Other than cleaning, checking/fixing the existing wiring he replaced the following parts and set the bias (once after restoration and again after letting an audiophile friend burn the amp in).
I'll be using it connected to my Outlaw 1050 but I assume I'll want a modern tube pre-amp to get the best out of my 2-channel system. I saw Kelly's list of tube pre-amps in the $600-$800 range. Is that the short list or are there other recommendations --not more expensive ones? I need phono cabability and actually will be exploring a TT upgrade after the electronics.
Here's the new parts list:
4 EL34 Eiectro-Harmonix tubes by Sovtek
1 GZ-34 Rectifier
4 Hovland Caps
1 JJ 20/20/20/40 Filter Cap (4 section electrolytic is mounted under the chassis, and the original has been left in place))
2 470 ohm 1/4W Res 1%
1 1N4007RT 5A diode
1 16GA H.D. Line cord
4 STD Rubber Feet
4 Gold RCA Jacks
8 Gold Plated 4-40 screws
I read several articles on modifications and restoration. This seemed like an inexpensive way to start by using the basic original design but with some important upgrades in signal caps/matching new output tubes/and gold plated connectors. Those that have heard the box feel it's a desirable representation of the ST70. I'm hoping it comparable to other ST-70's short of the modern redesigned mods that basically just use the chasis & transformers.
I'll be sharing sound impressions and bringing it to the D/FW Klipsch Forum for comparison to some other amps and for other opinions. My big question is will this extra effort make a notable improvement over my Outlaw SS (using the Outlaw for a preamp and then using a moder tube-preamp)?