ST70 clones

[hfh]

Can someone advise which ST70 clone kit is best? I'm considering the Triode Electronics, Tubes4hifi(Bob Latino), and Dynakitparts. Thanks for your input.

 

[Geek]

Hanging out with the ST-70 nuts at diytube, they're all pretty much the same, just different iron sources.

The Triode one is the best bang for the buck.

Cheers!

 

[Tom Bavis]

Dynakitparts sells kits that use two 7199 preamp tubes. NOS is hard to find and I think the Russian one is discontinued. It appears they are currently selling 6GH8 with an adapter. This circuit doesn't provide much voltage swing and really won't work well with the EL34s in triode mode.

The Triode kit or Bob Latino's both use a 3-tube driver that uses more readily available tubes and can swing more grid voltage.

 

[Geek]

Oh yeah, forget the 6GH8 and rewire for a 6AN8. It's closer to the 7199 in performance anyway.

You can also buy different driver boards to fit in.

Cheers!

 

[rknize]

If you are not too concerned about aesthetics, the Triode one is the most economical. It's a rough interpretation of the original chassis and apparently is not always punched exactly the same. It is stainless, so that is a bonus. Their driver board swaps the 7199s for a separate pentode and triode and so is probably about as close to the original design as you an get without using NOS 7199s or equivalent (for better or for worse). Triode's transformers are reproductions and are highly-regarded.

I have the Bob Latino kit and it is very nice. The chassis is stainless, but is true to the original design with the power take-off plugs (they are only used for bias), silk screen, and all. The driver is different but most agree it is an improvement over the original. The transformers are supposedly accurate reproductions with a higher capacity power transformer. Even so, my transformer still gets very hot after several hours of use. Bob's kit is available with some of the add-on packages he sells, like the triode/pentode switch kit, Russion PIO coupling caps, etc. He offers the kit with or without tubes and last I checked what you got was Valve Art (Shuguang).

Good luck!

 

[quadtech]

Trafomatic makes a ST-70 Toroidal transformer set. You can get them
from Boris at Vista Audio.

I am very happy with my set, using a VTA
board. Pics here (wiring is a mess; need to clean it up some day) -

http://picasaweb.google.com/prasadb/TubeAmp#

Vista Audio -

http://www.vista-audio.com/

 

[hfh]

I ordered Bob's kit. I like the original chassis, upgraded board and I like the power transformer better than Triode's;it has a bottom cover as the original. I ordered it with tubes and the cap upgrades. I talked with Bob when ordering and he seems to be a good guy. He is very accessible and will be there if you need help. Thanks to all , Chuck

 

[Geek]

Hi,

You might want to check out this "failsafe" bias for the ST-70. Adds some balance versatility too.

http://geek.scorpiorising.ca/GeeK_ZonE/index.php?topic=4230.0

Cheers!

 

[rknize]

Good luck with your build! It is pretty easy to do as the instructions are pretty good. One thing the instructions did leave out: while they have you soldering the heater wires to the PCB before you put in those big PIO caps, they don't tell you to solder the wires that lead to the output tube grids as well. It's doable but a little tight. I'd put all the wires around those caps in before the caps go in.