Sluckey Inspired Plexi/800 Build in Progress

[Mike_J]

Latest on the amp is I have decided to use the CTS 1MA potentiometers with the SPST switch built into the pot (pull it out to turn on the switch).  They will be used to set the bright caps for a Strat and a Les Paul.  The Les Paul should require a larger cap if I am correct.  Have a friend coming over with his Les Paul in a few days and I will use it to set the higher bright cap value.  My experience with my Strat is a 500pF cap across the bright volume pot on the Plexi side is just about right.  Haven't decided yet on the 800 side.

Pleasantly pleased with the overdrive channel using my Strat.  Does a convincing Texas Flood sound.  Hopefully my friend can help me get some audio on the forum.

Thanks
Mike

[Mike_J]

Put the CTS potentiometers with SPST switch built in for the bright volume on the Plexi channel and the volume pot on the 800 channel.  Set the Strat pot at 420pF and  .0047uF when the pot is pulled out.  The 800 channel has either no cap or 1000pF if I pull the pot out. 

All was going well until today.  The Plexi pot is not working properly.  Have to play around with it to get it to make sound.  Enough wiggling and it works okay until I want to change its value.  This is the second pot I have had trouble with on this amp.  Is anyone else having problems with their potentiometers?  I don't think there is something I am doing improperly.  Only choice if I want to keep it the same is to buy a new pot and use a 1MA in the meantime with a .0047 bright cap across it.

Secondly, I don't like the overdrive.  Sounds acceptable at low volumes but squeals like a pig when the volume is turned up, especially on the neck pickup.  Any suggestions would be appreciated.  Considering the Slash #36 as an alternative but I am open for other suggestions.

Thanks
Mike

[Mike_J]

Now it is making sound, most of the time, but it is not getting any brighter when I pull the switch out.  It was working well the other day.  Can anyone think of a reason it would quit working?  All the connections look and seem sound with the chop stick test.  Another thing I noticed is the normal volume control is having very little effect on volume or gain.  Almost all volume is controlled by the bright volume switch.  Shouldn't both volume controls have an impact on volume and gain?  Any ideas as to what is wrong?

Thanks
Mike

[Mike_J]

I think I fixed the problem.  Got a second hand Mullard that must have a very weak triode because the other tube I put in V1 made both the normal and bright channels work.  Getting my Hickock gm tester out to check the tube.  Guess is it wasn't what the seller said it was. 

The switch problem may also be fixed.  I had three pF caps on the pot to tune it in.  I removed one of them and it looks like one of the cap wires was precariously close to the ground tab and was probably touching it intermittently.  I clipped the wire shorter and all seems to be working now.

Thanks
Mike