Bassman 70 into ODS

[guitardude57]

Thanks Tom

[guitardude57]

Howdy,

I changed the 3k dropping Resistor, and that put the voltages right where they needed to be.

Got rid of the hiss, the clean is beautiful. Adjusted the OD trimmer to 41k to ground and that baby sings now.

The effect loop voltage is 250 and 233 so that cleaned up nice too. Amazing what one little resistor change does!

When I get a chance will post pix and clips. Thanx guys, Mike

[Structo]

Congrats Mike,
Always cool when the amp does what you want it to do.

[guitardude57]

Does anyone have a tweak or 2 for the middle tone control in the skyline eq?

I have several hours of play time on the amp, and very happy with the tone.... but the mid pot does very little at all. The fat/thin switch works, although subtle.

What can be done to strengthen the mid control?

[Structo]

Do you have a 250KA mid pot installed?

I too have noticed the tone stack on these amps are not real effective.
They sort of work together so if you want more mids bring up the mid and bass control.
When you wired the tone stack did you make sure that the two righ hand lugs on the bass pot are connected when in normal clean mode but disconnect when PAB is turned on?

[guitardude57]

Howdy structo,

There is still no relay set up yet.....hardwired switches for OD and PAB.
I've just been playing as is, to break everything in. Everything works great as is, just very little mid control. Almost zero..........

So Bass pot is wired single CW lug. Yes there is some interaction with Bass and Mid......but very wimpy. A little more pronounced at higher volumes.

I would think turning tone controls down, and one at a time get more volume/tone response. The treble and bass pots do this.....but with T/B all the way down (or bass slightly up) the mid does nothing. Strange.
All joints are conducting continuity, and wired correct. Maybe just skyline traits.

What ya think?

[ChrisM]

Try lowering the slope resistor, 120K or 100K maybe. If you do this you'll probably need to cut some bass, bring the highs back a bit.

[guitardude57]

Yes the slope resistor was in my thoughts.

If I were to drop it say, to a 100K......what change in the bass control would there be?

The bass adjustment is fairly low frequency in response, but could be more evident due to lack of midrange.

[ChrisM]

https://tubeamparchive.com/viewtopic.php?t=11729
Read the later posts in this thread.

You might need to tweak your OD trim ever so slightly, as your clean signal might be a tad hotter.

[guitardude57]

Thanks for the link Chris,

My OD trim is rear panel mounted