Regarding the OD1 in trimmer, did anyone measure the slider to ground ?
Obviously this is adjusted to taste, and an exact value might depend on lots
of things, but a ballpark value would be an interesting noteworthy point. Probably the most critical part of this setting would be this value. Dogears, are you party to this info, or do you have an educated guess on it? An amp I just did used 24K and seemed to be working right.
#0124 Again
Moderators: pompeiisneaks, Colossal
Re: highway 124 revisited
I heard it was 100K to ground....
butwhatif wrote:Regarding the OD1 in trimmer, did anyone measure the slider to ground ?
Obviously this is adjusted to taste, and an exact value might depend on lots
of things, but a ballpark value would be an interesting noteworthy point. Probably the most critical part of this setting would be this value. Dogears, are you party to this info, or do you have an educated guess on it? An amp I just did used 24K and seemed to be working right.
Re: #0124 Again
This seems hi to me, but would obviously depend on a lot of things. I think this value might be widely variable from amp to amp. What have you found to be workable values? This amp was before a trimmer and used 33K -
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Re: #0124 Again
If you have the normal 220K>100K trimmer, I would suggest anywhere from 30K to 56K to ground.
In the case of #124, the 220K feeds a 350K trimmer. 100K to ground with this much higher impedence network works out very similar to how Dumble would set them. In fact, my friend who owns a 100K plate Dumble, had the 100K trimmer set at 56K from ground w/ 220K feeding the trimmer.
In the case of #124, the 220K feeds a 350K trimmer. 100K to ground with this much higher impedence network works out very similar to how Dumble would set them. In fact, my friend who owns a 100K plate Dumble, had the 100K trimmer set at 56K from ground w/ 220K feeding the trimmer.
OD Trimmer modification mystery...
Just for the fun of it I took a late 70s era CTS trimmer that I had in a box and was able to take it apart without damaging it. The carbon is just a fine film on the surface of the phenolic wafer. Just a few swipes with fine sandpaper and it was up to 80Meg and then over level. I had it hooked up the the ohm meter as I was sanding it.
So that answers that question about modifying a 500K to a lower resistance by sanding the carbon.
I think I may still have some conductive paint used for guitar control cavity shielding. I might try putting that on the phenolic wafer and see what happens. Though I think the little wipers might wipe if off.
I keep finding more little things to change on the #124 schematic, like the 22m resistors by V1B...update to come.
So that answers that question about modifying a 500K to a lower resistance by sanding the carbon.
I think I may still have some conductive paint used for guitar control cavity shielding. I might try putting that on the phenolic wafer and see what happens. Though I think the little wipers might wipe if off.
I keep finding more little things to change on the #124 schematic, like the 22m resistors by V1B...update to come.
Re: #0124 Again
I just uploaded a 4th revision to the 124 schematic near the start of this thread.
However, a more complete schematic is posted by odourboy here:
https://tubeamparchive.com/viewtopic.php?t=4354
This thread should terminate and discussion should be moved over there.
However, a more complete schematic is posted by odourboy here:
https://tubeamparchive.com/viewtopic.php?t=4354
This thread should terminate and discussion should be moved over there.