Steele 70 MK II

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Does anybody know anything about this amp? I thought it was MKII or ST-70, but apparent it's not. Did Dynaco make this? I got this from the guy that I got my MKIIs from. He thought it would be fun for me to make one.

Schematic:

http://bp0.blogger.com/_i08-ibvZ150/RumpUBBtDnI/AAAAAAAAAMw/q6SDPnDEpso/s1600-h/SCAN0003.JPG

[Slartibartfast]

Does anybody know anything about this amp? I thought it was MKII or ST-70, but apparent it's not. Did Dynaco make this? I got this from the guy that I got my MKIIs from. He thought it would be fun for me to make one.

What is V5 used for?


Robert

[mesherm]

I would hazard a guess that V5 is some sort of magic eye tube to give a visual indication of output power.
Aside from the bells and whistles it is still basically an ST70. I hope that isn't a 100 mf cap coming off the 5AR4. Good luck using a Sovtek there.

[sorenj07]

Use a NOS 5U4GB and 22uF for the first cap and I think you'll be safe..

[erichayes]

The basic circuit (to the left of the eye tube) was supplied with Dynaco's A-430 and, later, the A-470 output transformers as a "suggested application". It actually started life in the Mullard labs to promote the use of their new audio pentode, the EF86, which might account for the fact that it has a European eye tube instead of, say, a 6E5.

There was another circuit Mullard developed that used an EF86 working into a 6SN7 LTPI, which was the basis for the EICO Hf87 and HF89 amps.

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Here is one on eBay right now. Looks pretty fancy. So, I guess this is some kind of a DIY mod for ST-70s?

http://cgi.ebay.com/Dynaco-ST-70-Steele-70-MK-II-Tube-Amplifier-NICE_W0QQitemZ290189191311QQihZ019QQcategoryZ50593QQssPageNameZWDVWQQrdZ1QQcmdZViewItem