no volume control on instrument input.

[harpslinger]

Hi Folks
Im brand new to this forum, I am a harmonica player working on old amps and mics for blues harp. Has anyone here ever come across an amp that has no volume control on the instrument channel? I have a 1946 Kiesel amp. I plugged a mic into the instrument jack and it started screaming feedback.
The volume control is off. I did not know where to start with this thing so I just put 2 new filter caps in which made no significant difference. But I did notice something after I did the unecessary work. First I checked to make sure the pot was not installed in reverse somehow. Nope  The microphone jack does respond to the volume control but the instrument channel does not. So my thought is perhaps back then Mr Lowell Kiesel (founder of Carvin amps) may have put a volume control on the microphone channel because most mics do not have volume controls but guitars do. He played electric steel guitar. Has any body here come across this kind of thing?

[PRR]

> most mics do not have volume controls but guitars do

Makes sense to me.

However "most" amp makers price their stuff as $1 per Watt, $10 per knob/jack, plus the Brand Name Value, so they will usually throw-in a knob if it costs less than ten bucks. I guess Lowell didn't see it this way.