Low gain in TS-808 Keeley mod

Started by bancika, February 15, 2006, 08:46:18 AM

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bancika

Hi,
I just finished my first pedal. TS808 with keeley mod, I used tonepad PCB layout. I changed 47nF cap with 100nF, 4.7K resistor with 2.4, 51K with 20K and I made third clipping diode switchable with DPDT switch, one one side diode, on other jumper. I havent test pedal without mods, it's just built with them.
The problem is, it just hasnt got gain like on some clips I've heard. And keeley mod should increase gain range, right? It's very mild. All pots are working with no problem.
Did someone have similar problem?
I'll post clips a.s.a.p
Thanks
The new version of DIY Layout Creator is out, check it out here


theman


the keeley mod should increase gain by 2X, but the ts808 is a low/mild gain overdrive anyways, so you might not hear a huge difference.  changing 51k to 20k increases the gain range *downward*, allowing a cleaner sound when the drive is fully ccw. you can change the drive pot to 1m instead of 500k. that will increase it again by 2x.


wampcat1

Also, that 4.7k you changed to 2.4k, go down to 1k, MAYBE 700 ohms or so for a bit more gain...


twabelljr

Remember, the lower you go with the resistor, You will have to increase the cap value  to maintain the same freq. roll-off. If you go down to 1k, use at least .22uf.
Shine On !!!

JHS

The Keeley mod is really cool, increase lowend mud and compression on higher gain, in short a crap-mod (the TS-clipstage was not designed for high gain).

Way better: a LPB-1 or something similar as driver in front of a stock TS and a bigger coupling cap (100nF) in the output buffer plus a bigger output cap (Sony Gold) with a small bypass cap  for addes treble response and bigger, yet clear bass.

JHS

gmr1

For the diode switch does it matter if it replaces diode 1 or 2? Is it a 3 post on/off/on switch with a jumper on one end, ground in the middle, diode on the other end, and the jumper and diode meeting at the other end. those go to one end of where the original diode was, and the ground to the other?

I know this is how I recall doing it with my D+ (pair of diodes, ground, pair of leds - with the pairs meeting at the board), but I didn't know if it's the same for a diode switch on a TS808.

Any insight would be appreciated. I have a hard time with the concept of switching for some reason!

bancika

Here's how I did it: you have ON/ON DPDT switch - 3 rows with 2 lugs in each row. when it's in first position it connects first lug of middle row with first lug of first row and second lug of middle row with second lug of fist row. In second position it connects midle lugs to lugs in 3rd row.
So, in the first row I connected diode, second row is connected to PCB and 3rd row is jumper. in 1st posistion it will place diode in circuit, 2nd position jumper. I hope this is correct :)
The new version of DIY Layout Creator is out, check it out here


gmr1

I'm having a real hard time following that (it's probably just me!).

Ok, I know the switch your using. Could you tell me whats connected to each post of the switch? (and where they go to the board?).

If this is the bottom of the switch:

1     2     3
__   __   __   Top Row
__   __   __   Bottom Row

I really appreciate it. I have an 808 I built quite some time ago with socketed diodes, and would love to add switching to the diode section.

- Greg

bancika

I made little drawing

If you used tonepad pcb layout you have place for third clipping diode, that's where you need to connect those two wires.
If not just wire it in series with one of diodes, I don't think it matters which one. Also, check diode direction when connecting that red and green wires
The new version of DIY Layout Creator is out, check it out here


gmr1

Ok, which of those connections are the diode and the jumper? The green and red wires going to the PCB, what posts of the switch are they coming from.

I apologize for all the questions. I don't know why I can't conceptualize switching very well!  :icon_redface:

I've tried to search the board plenty of times, and never have gotten an answer that's explained it to me.

gmr1

ah, nevermind. I got it. The lower part of your pic is the switch posts! Man, I'm dense sometimes! Thanks for the help!