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Author Topic: OK guys, this is my layout...  (Read 8914 times)
mcinku
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« on: February 25, 2009, 11:23:55 AM »

I owned an OTS for almost a year now. I started out with the S&M model and at first I was happy with it.
At first I was using clean channel only (along with my pedalboard) and I was happy. But hey D-amps are known for their OD and there was nothing wrong with S&M OD ch... the only problem was if I wanted to switch channels on the fly. S&M is not designed to do that well.

So my first mod was to bring the channels (tonewise) closer. I was changing things very slowly... resistor here, a cap there... each time playing the amp. Finally I came really close to the current OTS model.
Well I didn't remove the mater vol. cap and didn't change the 150K resistor to 180K (the one which sits before ratio pot).

With all those mods amp sounds about right to me.
'Cause I use all kinds of guitars with my OTS, my next move was to change the bright switch values, put a 390p on the mid-boost and I installed deep switch instead of FET (which I never used anyway). The goal was to achieve more variety for all those guitars.
Finally filter caps were added, bass cap changed to .001 (it had .0012 before), FET simulator resistor installed, lead dress changed a little and now my amp is complete.

Oh forgot to mention,... I also installed LNFB mod but the jury is still out on that one. Not sure yet but I might change that to something else.
Pre OD pot seems something worth doing.

Thank you all for helping me get there.
 Wink Grin


* My_OTS1.JPG (377.75 KB, 1746x1258 - viewed 1089 times.)
« Last Edit: February 25, 2009, 12:42:10 PM by mcinku » Logged

pine
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« Reply #1 on: May 01, 2009, 12:30:03 PM »

I notice that you have changed the value of the mid-boost cap from 330 pF to 390pF. Did this significantly change the amount of boost in the mid range ? I would think it would be less boost, which is what I'm striving for as I cannot use the switch as is. What does the second cap on that switch do, the .002uF? It almost looks as if the switch is bring that cap into and out of play when it is engaged. Would I have to increase that value as well to lessen the amount of boost I'm getting?
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mcinku
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« Reply #2 on: May 01, 2009, 06:20:04 PM »

I notice that you have changed the value of the mid-boost cap from 330 pF to 390pF. Did this significantly change the amount of boost in the mid range ? I would think it would be less boost, which is what I'm striving for as I cannot use the switch as is.

Changing that cap will not affect the amount of boost... it will change the freq. and not level.
I tried 390p 'cause some originals used that cap. After this change, I think both caps work just fine...
Sorry, don't know how to decrease the boost level with that switch... maybe just one idea how to use it. Switch to the jazz mode, mid boost and bright on and what you get is very convincing tweed tone...  Wink

What does the second cap on that switch do, the .002uF? It almost looks as if the switch is bring that cap into and out of play when it is engaged.
Are you talking about the second cap on the bright switch?
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hywelg
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« Reply #3 on: May 01, 2009, 06:36:10 PM »

I notice that you have changed the value of the mid-boost cap from 330 pF to 390pF. Did this significantly change the amount of boost in the mid range ?

Search through Pickmasters posts, he's got a mod that puts a pot in the FET input hole that controls the level of the PAB.
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pine
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« Reply #4 on: May 01, 2009, 07:28:15 PM »

My apologies, I was speaking of the mid-boost mini switch, not the PAB footswitch. The second mid-boost cap I was speaking of, if you look at your layout, and follow the (B-3 on the standard OTS layout) wire from the pin on the switch (where the 4M7 resistor is attached to ground) and follow it to the board there is a .002uF cap
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mcinku
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« Reply #5 on: May 01, 2009, 08:13:40 PM »

My apologies, I was speaking of the mid-boost mini switch, not the PAB footswitch. The second mid-boost cap I was speaking of, if you look at your layout, and follow the (B-3 on the standard OTS layout) wire from the pin on the switch (where the 4M7 resistor is attached to ground) and follow it to the board there is a .002uF cap

Aaa I see now,... I believe that's a coupling cap and that one is always on.
I never played with coupling cap but I think if it's bigger, the amp will have more bottom end... something like that, I'm not sure.
 Wink
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mcinku
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« Reply #6 on: May 01, 2009, 08:21:40 PM »

Search through Pickmasters posts, he's got a mod that puts a pot in the FET input hole that controls the level of the PAB.

Are you sure? I think he's not even using a PAB anymore (I mean D style PAB). What he has is just a level... so it acts like a boost. He disconnected a PAB and wired that pot.
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erwin_ve
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« Reply #7 on: May 02, 2009, 07:10:07 PM »

mcinku: you got all nice little things in there!

Smart move on the PT primary selector. Think I'm gonna do that one also. (I read about it a while ago and forgot...)
The LNFB switch; how does it sound with clean PAB when switched out?

If you're using a  Kleinulator or something, you might want to experiment with the MV cap; I got mine just a bit bigger(33pF).

Thnx for sharing!
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mcinku
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« Reply #8 on: May 02, 2009, 08:49:02 PM »

mcinku: you got all nice little things in there!

Smart move on the PT primary selector. Think I'm gonna do that one also. (I read about it a while ago and forgot...)
The LNFB switch; how does it sound with clean PAB when switched out?

If you're using a  Kleinulator or something, you might want to experiment with the MV cap; I got mine just a bit bigger(33pF).

Thnx for sharing!

Thanks  Wink
Last time I was inside my amp I moved pre OD pot to the back and I currently disconnected the PT selector... I must find another type of a switch... with this one, it's a little dangerous poking inside a live amp. It's to easy to accidentally touch something with that switch wired like that.
Regarding MV cap... I was thinking abut using Push-Pull pot and try some caps.

 Wink
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mcinku
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« Reply #9 on: May 02, 2009, 08:56:45 PM »

Forgot to mention LNFB  Tongue
Well that switch is very subtle... what you get is a slight (just a little) boost and maybe some more bass and hi end is getting through. Like I said very subtle mod... don't expect to much with that mod.
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roadapple
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« Reply #10 on: May 22, 2009, 05:25:12 PM »

Am I correct to "assume" (we know where that lead us!) that the mini-toggle you use in place of the FET input is a DPDT?

I have all the parts to do the mod, and I purchased a DPDT switch, and then got to thinking....

Thanks!
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mcinku
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« Reply #11 on: May 23, 2009, 07:09:15 AM »

Yes that's DPDT switch
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