som one how to implement a tone control on Double D (runoffgroove.com)??

[solderman]

Hi All
I have just finished the "Double D" (runoffgroove.com)
A two channel distortion built around a CD4049UBE witch I find to be a very interesting circuit and god sounding in a odd way too.
(I might have found an error in the text though. Shouldn't The text PIN 3, 13, 16  NC" be PIN 6, 13, 16 NC" 3 needs to be connected as shown in the circuitry as I See it??)
About FET:s have you any suggestions of a replacement for J201. They are quite rare in Europe (Sweden) and it takes some time and costs a bit of shipping to order small portions from Smallbear even if he is my choice of "electronic pusher" for rear IC and trannies. I tried the MPF102 but I have to drive it hard to get a good sound in "Jiggle" but then the "bounce" gets to hizzy. have Som one  any suggestions on the drain voltage on Q1

I like to try to implement some sort of tone control, especially for "bounce" since the 47n and gain seems to make a high pass filter that really has an effect on the tone between no and full gain. Any ideas? Maybe something like the TS 808 between 12 and 14??



It's quite an easy build but a real challenge to box because of all the wiring up of the off-board components. I always use shielded cable from the in-jack to the circuit in all my dist/ OD projects. This is because of the interference in high amplification/dist that will to avoid to be amplified and to reduce the unwanted hizz.




//Solderman

[gkoerselman]

I'm in Germany and I get all my stuff (J201 included) from http://www.banzai-effects.com/ who are located in Berlin Germany I think. Also located in Germany is http://www.musikding.de/.

Both sites are in English and I find their offerings covering everything I've needed so far (including LM386N-3's which I needed for my Krank DM clone).

[tackleberry]

In the text for the double D it says any of your favorite tone controls can be plugged in. Im waiting on the parts to get here to build a double D with the marshall style tone controls. But a basic TS or big muff style tone could be put in pretty easy. Might be a tight squeeze in the box your using. Im going with the 1790 size for more room for the knobs.

[bolidin]

HI
although less power 2n5457 work instead of j201 though they give less gain
i like them even better
respect javi

[Ripthorn]

I just built one and have found that the bounce channel on mine seems to actually add some low end.  It's not too much, but enough to give a great full bottom end.  I, too, was considering a tone control, as the bounce channel does seem bright, but I think I will stick with it as-is.  Let us know how it turns out if you put a tone control in it.

[stm]

(I might have found an error in the text though. Shouldn't The text PIN 3, 13, 16  NC" be PIN 6, 13, 16 NC" 3 needs to be connected as shown in the circuitry as I See it??)

Thanks for noticing that.  The DD project has been updated with a minor revision that fixes this error and includes proper power supply filtering.  The perfboard layout was updated accordingly.

About FET:s have you any suggestions of a replacement for J201. They are quite rare in Europe (Sweden) and it takes some time and costs a bit of shipping to order small portions from Smallbear even if he is my choice of electronic pusher for rear IC and trannies.

I suggest you try with 2N5457, BF245A or 2N5484, if possible.  You should go with the specimen with the lowest VGS and IDSS spec in each family.  MPF102s are one the other side, so they are not a proper replacement, as you already noticed.

Drain voltage on Q1 should be set within 4 and 6.5V.  You can set the drain voltage to 5V and adjust the trimmer around this point while listening to the circuit and find the sweep spot by ear (after all you are building the circuit to please your ears!).

[solderman]

Hi
Since I first posted this question I have built 3 of the Double D. I really like it for its versatility with two channels. The latest build was the one you can see below in a 1590A box. I redesigned the   design and put the gain and volume put outside the switch for the obvious reason that there is not enough space to fit 4 pots in this type of enclosure. I did include a tone pot on my second build. I did this by including the simple type tone control where you hook up a 47nF cap in series with a 10 KA pot wired as a variable resistor to GND in parallel with the out pot. It works grate as a treble roll of.
In all 3 builds I have had problem to balance the gain from the input FET with the trim put. If the gain is OK in the "Jiggle" it starts to oscillate in the "Bounce" at max gain/vol. If lowered to just under oscillation in "Bounce" it gets choppy in the decay in the "jiggle" To fix this I have tested different values on the resistors parallel to 3-2, 9-10 and 14-15. I did this by changing those to a 1M B pot wired as a variable resistor and tweaking to a working level and then measuring with a DDM and use a resistor closest to the measured value (I can´t remember what value right now) I have tested about 10 different FET:s and end up with that J201 and 2N5457 gave the best sound.
In my next build I will test to redesign the input stage so the switch is before the FET and add a second FET and trim pot for the different channels.

//Solderman

Sound
Crappy sound sample too. (the one in the pics)
http://solderman.fatabur.se/Future%20project/TT-02.mp3

Pic:s

[stm]

Very nice little build!

You are having an oscillation / feedback problem at high gains, that's for sure.  I assume the unused inverter input is already gorunded (pin 7).  This leaves feedback coupling between input and output wires, and/or Gain / Volume pots.  A way to go would be using shielded cable in each jack and pot--a PITA, but I guess it might fix the problem.

It is very likely that the setting for the Bounce channel has the JFET just in the cutoff region, so it just cuts feedback possibility.  At lower gains this is more noticeable and sounds gated in the Jiggle channel.  Could you post the drain voltage of the input JFET in each case?

[solderman]

Very nice little build!

You are having an oscillation / feedback problem at high gains, that's for sure.  I assume the unused inverter input is already gorunded (pin 7).  This leaves feedback coupling between input and output wires, and/or Gain / Volume pots.  A way to go would be using shielded cable in each jack and pot--a PITA, but I guess it might fix the problem.

It is very likely that the setting for the Bounce channel has the JFET just in the cutoff region, so it just cuts feedback possibility.  At lower gains this is more noticeable and sounds gated in the Jiggle channel.  Could you post the drain voltage of the input JFET in each case?

Hi
Thanks for the kind words.

Yes, pin 7 is connected to GDN. I have already tried shielded wires as you can see in the Pic below. It's from my first build. It's the one I tried a lot of FET:s and resistors on. You can see the socket for the FET and resistors in the Pic. I wrought down the final value of the resistors on a piece of paper. Unfortunately I have misplace it and the pedal is sold to a friend so I cant recall the values. The small one above is built with stock values. The drain voltage is 6,55 V adjusted to give the "Jiggle" a good sound without choppy decay. I adjusted the trim pot before I mounted the PCB in the box. So now I can't reach it without demounting the ting. BIG TIME goof from my side. I corrected this in my mini Thor build (see pic) I think I have to drill a whole in this one too.

\\Solderman

Inside of my first Double D (huge pic)
http://solderman.fatabur.se/DoubleD/Viper_Inside.jpg

Solderside of my mini Double D


Solderside of my mini Thor