Hi folkd I am troubleshooting for very excessive distortion on channel 2. I have been doing some trouble shooting, checking resistor values, volatages ect. Swapped some tubes, Traded position of various op amps. No improvement. Cap job done, all e-caps changed. Stock values. Some diodes replaces. I think I have narrowed it down to the channel 2 volume dual gang volume pot. Looking at the schematic is it telling me that 1 pot is 10K linear, the other is 10K audio taper? See image of schematic attached. If I am correct, does this 10K pot appear to be correct? Thanks in adance. - Keith
https://www.tubesandmore.com/products/potentiometer-alpha-linear-solid-s...
Images:
First off-what amp is this?
First off-what amp is this? Mike.
Sorry..,1980 212 Sixty-Five.
Sorry..,1980 212 Sixty-Five. Solid state phase inverter.
I was trying to find a replacement pot. After reading through this site I found a thread on the topic. I will order both a dual audio taper and dual linear taper. Try both, see which one sounds better. Add a resistor is needed.
Channel 2 pot is a little noisy. I’ll replace it,
Hello Keith,
Hello Keith,
I am very interested in your subject because I have been looking for this type of potentiometer for several years. The LM307H OAs are mounted as inverting amplifiers. So the 10KL mixes the reverb signal with the signal of the first amplification stage before attacking the IC-4 op-amp placed before the last preamp stage (IC-7). The 10KA mixes the signal with the tremolo just at the last stage of the preamp (GB-1 board). I think you risk generating a much less progressive stroke with a double logarithmic rather than a linear/logarithmic one, isn't it ?
Have a nice day
Direstrat
newark
You are way out past me on this job. I applaud you
The only thing I do know is that, if Newark doesn't have it, it doesn't exist.
I used to read the print catalog on breaks at work and OMG, there were 20 pages of pots in tiny print!
https://www.newark.com
yours scott
I have mixed pot components in the past!
I see alpha has both audio and linear dual pots, you may need to build your own!
Hello Bill,
Hello Bill,
This is exactly what I'm going to try !
Have a nice day !
Direstrat
Re Dual Gang Pot
I ended up buying both a 10K dual gang linear, and a 10K dual gang audio pot. I was about to try each of them and pick the one that sounded better. When I removed the original pot in the amp, one pot was stamped 10K L. The other pot was not stamped at all. I reasoned that maybe the dual gang pot was comprised of 2 linear pots only. So I installed the dual gang 10K linear pot that I had bought. It seems to work fine. Volume, reverb and tremolo are all working.
Dual Gang Pot
Hello,
The easiest way to know if it's a linear or a log is to measure the resistance value of the pot set to 50%. If the value is higher than 5KOhm, the potentiometer is logarithmic (audio).
I receive Alpha dual pots : dual linear and dual log. Making a mix of the two seems difficult with this brand because the axle is attached to a black plastic part which seems not to be removable without damaging it... Let's see if I can find some CTS...
Have a nice day !
Direstrat