Stepped Attenuator to replace Potentiometer.

Now I understand, that's why I ask how old. I knew anything in the last 20 years had no volume pot.

Good call on the impedance issue, that's mandatory to maintain. I'm not qualified to tell you what to change to make it right. Have you tried to contact Wolcott audio for advice? Hank is very bright.

Try Shallco.. http://www.shallco.com/attenuators.html

Thanks for the responses. I have not contacted Henry Wolcott as of yet; he and Mr. Lomax are quite busy (great, knowledgeable gentlemen by the way!), so I might first try the technician who knows these amps well enough to wrestle with their intricacies and quirks. Eldartford, I went to the DACT website and they offer the reknown CT-2 Attenuator, with the greatest resistance rating at 500kOhm. Given the gain pot on these monos indicates 25 meg Ohm -- and if my calculations are on track -- do you mean I would need to increase resistance by 50 Ohm were I to get the 500kOhm Attenuator? I'm not an engineer, so I just want to clarify.

I called Shallco and await response on an attenuator with a closer if not equal impedance match. You guys sure seem to know your stuff: Thank you for your informative suggestions, and long live audio engineering in advancing the Arts & Sciences.

Somut...You better check on the resistance of that pot. 25 megohms is far higher than any audio gain pot I have seen. I could believe 25 Kohms, although that would be a bit low.

Marchand can make custom attenuators. More expensive than DACT but at least worth an email. The DACT is series, as opposed to ladder, if I remember correctly. Size might be an issue as well. Goldpoint could be another option (goldpt.com). I have never seen anything over 100K but it might be possible with a shunt. What wattage are we talking about here? And what range? Is it possible to get a meter on it? Powered off, of course.