Build Your Own Clone Message Board

Hey all,
I'm trying to add a Soft-Clipping mod in my Refractor Klone, but don't know how to wire it on to the PCB. Could you help me figure this out?

I've attached a photo of the PCB and what I think is the relevant part of the schematic. For reference, here's the post that shows the soft clipping mod:
http://tagboardeffects.blogspot.com/2014/05/klon-centaur-with-optional-bass-control.html

Best,
Eddie

OK, you definitely want to put the soft clipping switch into the feedback loop of the gain stage (IC1B). Using the BYOC Crown Jewel for guidance (since it also incorporates switchable soft clipping), I modified your schematic (see below) as I interpret the connections that need to be made. The part that I'm not completely sure about is the impact of the connection coming in from the gain control to the feedback loop. I'll see if I can get "the big guy" (Keith/byoc) to take a look at this and validate or correct my modified schemo.

Couple of additional comments:

• The soft clipping switch (on/off/on DPDT toggle) is connected in parallel to R12 and C8 in the IC1B feedback loop. A convenient way to do this would be to wire it in to the two legs of R12 just above the PCB.
• There also needs to be a resistor/capacitor pair connecting to ground from the pin 6 side of the feedback loop; that side of R12 would also be a good connection point for this. The resistor value determines the available gain of the circuit and, in combination with the resistor, sets the distortion rolloff frequency through the RC pair to ground. Don't change the resistor value, but you can try different cap values depending upon how much bass you want in the output. The 220n value shown will give you performance very comparable to a stock TS808 clipping stage. If you want more bass than that, try a higher value, like 470n (my personal preference) or 1uf. At some point, it will start to sound muddy, so I wouldn't go higher than 1uf.
• For whatever reason, that RC pair in a TS circuit is usually grounded through the 1/2V power rail (referred to as VB on the Refractor schematic), but I see that the GuitarFX vero diagram has it grounding through lug 1 of the footswitch. That's probably the easier way to do it.
• The choice of clipping diodes for D6 - D9 is up to you. A pair of silicon diodes like 1N914 or 1N4148 on one side of the switch with a pair of germanium diodes (1N34A or 1N270) on the other side is a popular choice, but there are almost limitless possibilities. Knock yourself out!

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Just an observation:

The added resistor and cap is not needed. You already have this combo attached to the gain pot, except it's connected to VB instead of ground (which is perfectly acceptable). Also, you could just use a center off SPDT to switch between two pairs of diodes since you only need to lift one end of each pair.

_________________
RIP madbean v.1

Ah, great--I thought that might be the case but I wasn't sure. Thanks for clarifying, Bean!


Good point. I just used what had been shown on the GuitarFX vero diagram.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Thanks so much man! I’m gonna takes some time reading through this multiple times as my schematic reading skills are still very underdeveloped!

Appreciate the clarification on this! By the way, do you prefer the Bass contour pot or the fat switch option? I saw on a post on your forum that you had them both

Ok, so I read through all the previous replies several times and I think I get it…

Are these statements correct?

1. Lugs 2 and 5 of the toggle need to be wired in parallel with R12 (or C8). Would another way to accomplish this be to wire R12 across lugs 2 and 5 of the switch and have wires also come out of those lugs to the R12 pads on the board? If so, what are your thoughts on wiring it this way?

2. I do not need to create an additional connection coming out to the R12/Pin6 connection point, as per MBs reply.

3. This soft-clipping mod adds soft clipping into the FB loop, but DOES NOT remove the hard clipping from the circuit when soft clipping is selected. In other words the Hard Clipping is always active.

Thanks!

Like this. It give you nine possible clipping choices. 3 for soft and 3 for hard. The middle position of each switch is no clipping. It will work for all positions except when both switches are in the middle position (no clipping). That actually sounds good but above halfway on the gain pot and it will start to motorboat.

_________________
RIP madbean v.1

Thanks! Big help!