Old Direct Drive Mods

[mjcyates]

David, Ronni,
I recently picked up an old version of the Direct Drive. It was a hand lettered model. I am wanting to do some experimenting with it and was wondering...

Is there a way to make the harmonics footswitchable as opposed to the push pull pot? If so could I also do something to add a volume boost when this is engaged?

Is there a specific resistor I could replace with a pot to alter bass response?

Is there a specific resistor I could replace with a pot to alter mid response?

[David Barber]

And now, my memory will be taxed.

I think the resistors on the left side of the PP are harmonics and the resistors on the right are mid response.

I think you could replace the PP with a 50Kb pot, then add a harmonics control with a value of 100k and a mid control with a value of 10K with a 3k resistor as a bottom out (total 13K). Install the deep bass mod from the tweaks page and sub the resister with a 50Ka pot. You might need a presence mod when you are done, so sub a 5K pot for the presence R.

[mjcyates]

Thanks David, I'm sure I will have more questions if I proceed down this path.

[mjcyates]

Ok so I successfully completed the deep bass mod. For now I am just using a cap and resistor (no pot). Next I want to try a mid pot. On the right side of the push pull pot there are two resistors, 15 k top lug to middle lug, 13.3 k middle lug to bottom lug. So for the mid pot would I remove both resistors and then wire one outside pot lug to top and the other outside pot lug to the bottom? Also can you tell me which resistor is the presence resistor?
Thanks!!!!

[David Barber]

Ok so I successfully completed the deep bass mod. For now I am just using a cap and resistor (no pot). Next I want to try a mid pot. On the right side of the push pull pot there are two resistors, 15 k top lug to middle lug, 13.3 k middle lug to bottom lug. So for the mid pot would I remove both resistors and then wire one outside pot lug to top and the other outside pot lug to the bottom? Also can you tell me which resistor is the presence resistor?
Thanks!!!!

You would use the wiper and an outside leg. You need to add the presence mod in order to be able to start adjusting the presence resistor.

[mjcyates]

Ok I'm with you now. I went a little brain dead and didn't realize you were referring to the "presence mod" from the tweaks page. So basically in both the "Deep Bass Mod" and the "Presence Mod" I can replace the resistors with pots. Got it. Thank you very much!

[mjcyates]

Ok so I put the old Direct Drive in a new enclosure, I moved the push pull harmonics to a toggle, I did the deep bass mod, and I put in a second volume pot wired to a 3pdt switch with led. Everything is working perfect except when I switch to the second volume pot I get a loud pop. What can I do to eliminate this? (add a cap or resistor somewhere?) I am going to add a pot for bass and presence as well. When it is complete I will post pictures. Thanks in advance for any help!

[David Barber]

Ok so I put the old Direct Drive in a new enclosure, I moved the push pull harmonics to a toggle, I did the deep bass mod, and I put in a second volume pot wired to a 3pdt switch with led. Everything is working perfect except when I switch to the second volume pot I get a loud pop. What can I do to eliminate this? (add a cap or resistor somewhere?) I am going to add a pot for bass and presence as well. When it is complete I will post pictures. Thanks in advance for any help!

What are you using the second volume pot for, and how is it wired? Diagram?

[mjcyates]

I am using the second volume pot so that I can switch between two different preset volume levels. I have the first pot set at unity gain for rhythm and the second pot set for a volume boost for lead. The diagram I am using can be found at http://www.beavisaudio.com/techpages/Switches/. Scroll to the bottom of the page to see Creating a dual volume control. Thanks, Marvin

[David Barber]

I am using the second volume pot so that I can switch between two different preset volume levels. I have the first pot set at unity gain for rhythm and the second pot set for a volume boost for lead. The diagram I am using can be found at http://www.beavisaudio.com/techpages/Switches/. Scroll to the bottom of the page to see Creating a dual volume control. Thanks, Marvin

I would either wire your dual vol the way we do on our TP and BU, or maybe try adding a 1m resistor from the connection they call "input" to ground.

On the TP and BU, use two 100K pots connect the output wire from the PCB to the left legs of each of the pots (looking at the back of the pot), then you tie the right legs to ground and simply switch the wipers to output, if you want you can control to drive pots with the same footswitch like the Bu and TP.