dynaco st 70 what tubes to replace first

Another voice heard from. I run Klipsch Fortes with mine and would say that the biggest difference was going to a Mullard 5AR4. Any Stereo 70 can use 6L6, KT66, EL34, 6CA7, KT77, etc. For power tubes, I would suggest getting away from the EL34/KT77 family and moving to some nice RCA 6L6GC or similar.

I will agree that *most* st 70's will bias 6l6 or kt66 tubes properly, but some will not without a resistor change in the circuit.

My amp has new much higher quality bias pots with a wider adjustment range than stock.... some stock bias pots may not turn the bias low enough without a resistor change in the circuit for the 6l6, kt66 tubes... while this may not seem like a big deal to most people here, the reason some may buy a rebuilt amp is they have no desire, expertise, tools, etc. to change anything in the circuit.

I have been in this hobby for almost 35 years and have owned countless speakers, seperates, recievers,etc.You are on the right track going with a rebuilt st70. It is the best sounding amp I have ever owned and cost much less than many of them. I will never go back to solid state amps again!

As mentioned by a previous poster don't let anyone's personal experience be the end all to your decision.
What works in my listening room may sound horrible in yours.

Power tubes for a dynaco st70 are cheap enough to play around and have fun with....

A Dynaco brought up to spec's is ok done right.A repainted one hides the transformers.There are transformers with cloth leads that sound totally different that the early ones.I went through about 20 or more of them.When everybody went to SS,there wasn't much choice for someone who wanted tube amps.You had to buy vintage amps.Some say they started out sourcing the transformers without the employees knowing about it.You could make them bias up for a 6L6 family tube,but any tech knows it is not made for them! At 4300 ohms for the A470 vs. the over 6000 ohms compatible for the 6L6 family.It's easy to buy a rusted Dynaco cheap and repaint it.There are people out there putting different transformers in the old Mac amps too.If there is a buck to be made,somebody ruthless out there sure will jump in.The early Dynaco 70 that has transformers similar in shine to the old Mac gear are the best ones.

Gentlemen: Esp Dave65mus, Rodman99999,& Viridian
I am so gratefull for the time you have taken to respond.

As a novice in this field of audio I appreciate your knowledge and passion.

I"ve got the new NOS ordered and look forward to Listening but also following your opinions on the threads.

Lawrence

I also own a Will Vincent rebuilt ST-70 wired in triode. I ended up changing all the tubes. RCA 7199's made a positive difference. I tried SED "winged C" el34's and a quad of Siemens el34's. I much prefered the Siemens, winged c's being too rolled of at the top for my taste.

But getting a Mullard fat base gz34 made it sound like a whole new amp. A much better amp. I actually couldn't belive what a positive impact it had on the sound. So if I had a limited budget for tubes, I'd spend my money on a Mullard gz34 first.