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Here Are Some Pics Of The ST-70 I Just Recieved From Ebay. It Works In Its Current Condition But I'm Not Going To Chance Running It For Too Long. Parts Will Have To Be Ordered, Chassis Stripped And Cleaned, Trannys Thouroughly Inspected, Ect. I Will Keep You All Posted On The Transformation Process. This Is Giong To Be Fun. Yellow_Light_Colorz_PDT_12
http://hilldwellerstl.myphotoalbum.com/ ... me=album02

Nice amp! Hardly looks like it needs rebuilding - except of course it needs a new driver board.

Good Luck!

Yellow_Light_Colorz_PDT_12

Looks like you have a 5U4 installed in your amp. I would replace it with a 5AR4 because as it will be easier on your power transformer.

Regards,
Sal Brisindi

WA4SWJ wrote:Nice amp! Hardly looks like it needs rebuilding - except of course it needs a new driver board.

Good Luck!

Yellow_Light_Colorz_PDT_12

Why would it meed a new driver board?

Sal Brisindi

Sal Brisindi wrote:Looks like you have a 5U4 installed in your amp. I would replace it with a 5AR4 because as it will be easier on your power transformer.

Regards,
Sal Brisindi

Thanks Sal, I Was Considering A Solid State Device That Acts Like A Rectifier Tube. However I Don't Know Much About These. What Is Your Take On This? See Link,

http://www.webervst.com/ccap.html

Personally I would replace the 5U4 tube in your amp with a Sovtek 5AR4 which cost $10-$12 range on ebay. That is what I use on my ST-70's. You can always buy a Amperex or Mullard but be prepared to spend big $$$$.

When you replace your quad filter capacitor buy the 80/40/30/20uf capacitor instead of the original size of 30/20/20/20. You will get better bass response if you play your music loud. Just make sure you wire it 40/80/30/20. Input from the 5AR4 connects to the 40uf section, the audio transformers to the 80uf section, then 30uf and 20uf to the rest of the circuit.

Regards,
Sal

Why would it meed a new driver board?

Better sound of course. In my old ST-70 I replaced the old Dynaco driver and it now sounds far better. Of course, that's my opinion.

Regards,

Since I have 2 ST-70's I should replace one of the driver boards with Shannons to compare the amps but I like to keep things original, plus my original circuit boards are in good condition. I will experiment with different tubes, 6L6 to be exact...


Sal

WA4SWJ wrote:

Why would it meed a new driver board?

Better sound of course. In my old ST-70 I replaced the old Dynaco driver and it now sounds far better. Of course, that's my opinion.

Regards,

When you say better sound, what exactly do you mean? More highs, more lows? Midrange clearer? I know sound is very objective between listeners.

Sal

Hi Sal, I know what you mean by keeping things original. That's one thing I like about the Diy board, it almost looks like the original except one extra tube.

Replacing capacitors is the best way to prevent thermonuclear meltdown. There's a good article on antiqueradio.org (phil's old radios) on restuffing old cap casings for the original look.