Tenebrion Mods (Grind Customs reverb)

[LaceSensor]

Hi all

A little while back I posted my build report of the Tenebrion.
http://www.madbeanpedals.com/forum/index.php?topic=11264.msg101455#msg101455

I made a mod at the time, which was to add a "short/long" decay switch.
I acheived this using a Dual Gang B100k pot, which I changed a wafer for a B1k, to make a "custom" dual pot.
You could easily do this by simply adding two potentiometers if you cant or wont hack a dual gang.
You may also be able to mod a dual gang with a resistor across the lugs..

I also changed the feedback to B500k to go into more "infinite" territory...

Anyway, after I built it I thought it was pretty cool, but wanted to tame the output.
Inherent in the design is a 10k mixing resistor (R7) and the way it is set, always sits a touch above unity.
You'll notice that if you set your reverb mix to zero, and switch between on/off, there is a bump in volume.
I didnt like this, so discussed with Rej and came up with the following:

- Switch out R7 for a slightly higher value eg 15k or 22k (I used 22k)
- Add a 500k pot at the output

This increases the gain of the output opamp, and then tames it by bleeding signal to ground at the output.
Its pretty easy to hack together using a B500k trimmer.

Here is a schematic showing my mods. Credit to Rej, I just used MS paint to mod his original
I have the short and long verb pots on a DPDT switch (S1a, S1b in the schematic)

Takes the project to another level for me.
The 100k reverb pot maxed with the feedback dimed actually goes into self oscillation, its pretty rad.

[GrindCustoms]

Nice work Ian!

Just to clarify, most of the credits on this project goes to CultureJam/EffDub,

I really dig your dual gang pot mod, if you want to get the most out of the opamp blend portion, use a 33K in R7, it makes the unit REALLY loud, but it's no problem with the output pot you added.

You could also jump up R11 to 47K and you'll be able to get oscillation out of a shortbrick and the infinite resonance it's able of aswell.

If you'd like to push your volume control to a active control, you can ommit the Vref buffering, to do so....

-Cut the traces of pins 1-2-3 of Opamp
-Run a lead from C10(100uf) positive pad to R2 or R9 pad that is traced toward Pin3 of Opamp

Now we can use IC1A as an output buffer. Using a klonish style buffer would make it really easy...running leads 1-2-3 to a vero with the klon buffer passives hooked to a B5-10K pot between pins 1-2 and you're set....