dynaco st 70 what tubes to replace first

Just to follow up on the system synergy part of my previous post... I have a pair of klipsch heresy's with new crossovers and also a pair of klipsch kg4's.

I have set up both speakers in my system and did not like the sound.

I have a bryston 3bst amp also, and both of the klipsch speakers sounded better with the ss amp than the dynaco?
Most people swear that the klipsch speakers beg for a tube amp but they did not sound good in my setup.

My quad 11L mini monitors have better bass (tight and quick) and much better detail than any of the klipsch speakers..... but where the 2 way mini monitors shine are the incredible imaging and soundstage width and depth they produce compared to the klipsch speakers.They "dissapear" and sound so lifelike with the st70 powering them. If I put the bryston in the system, it sounds good but no where near the level of tube power to the quads???? 86 db speakers sound better than 96db speakers with tubes???

System synergy..... only experimentation will find what sounds best to you.

Good Luck

It's important to note that there are many variables that will determine, or limit, a listener's ability to discern improvements/changes in presentation. ie: A system(source/pre/speakers/cables) that does not present or pass the info on the recording, poor recordings, room acoustics, aural acuity(actually; the lack there-of), the untrained ear, and the ubiquitous mental block(a refusal to hear what is obvious to others, because it doesn't agree with your mindset). Don't let the opinion of another stop you from experimenting with your own system. There are numerous simple/inexpensive mods and tube upgrades for the ST-70, that will yield much musical pleasure, if you ignore the naysayers(again- providing the rest of your system, and your ears, support them). Besides- It's just fun to experiment! Happy listening, all.

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.