ST70 input options to replace stereo/mono switch

I was reading an old article from Frank Van Alstine that recommended replacing the stereo/mono circuitry with a bandwidth limiting filter consisting of a .02uf cap in series with a 10k between the RCA + and the board. Additionally a parallel 475k/1uf combination goes from the board input to ground. Has anyone done this or have any opinions one way or the other? Otherwise I can just stick with the old 470k's center pin to ground. As always, thanks for your time!

Sound Values, later known as Sound Valves, thought it worthwhile enough to copy it in their reissue Stereo 70 (they bought Dynaco's parts stock from Tyco at the shutdown). Panor, in their Dynaco Stereo 70 Series II, also copied it. All the copying was done without the permission of the originator, Frank Van Alstine. Some sources say that Panor subcontracted the manufacture of their Series II to Sound Valves, which would explain a lot.

If you read comparisons of the Panor (with the bandpass filter) vs the original (without it), be aware that the input/phase inverter tubes are different. Panor used the 6GH8, since they could not source the 7199.

Can you tell me where to find the Articles............. more info on this..Have you done this mod?? Has anyone heard this setup in any Dynaco Amps are other tube amps.......
.thanks..... for your posting







Thanks for the Site Bob..............

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