Best Ever OD

[X]

I have the Best Ever OD PCB and would like to change the distortion voicing. Can someone confirm which diode(s) affect the hard clipping? Ideally, I would use a switch to toggle between the stock mode and the new version, but I’m not sure what to swap and don’t want to go crazy with adding sockets. TYIA

[Barry]

D3 through D6.

I really have no specific suggestions other than perhaps trying LEDs, but clipping is very subjective. Experiment and have fun.

[X]

If I’m reaching the schematic correctly, D3-6 are all in a series with no interruptions, right? So I could just wire them all offboard in series with a switch that begins at the start of D3 and ends at D6’s end to switch between the stock and the alternative diodes, right?

[brd]

D7 and D8 are connected from the signal path to ground (or VB) they provide what is referred to as hard clipping. the other 2 sets of clipping diodes (D1, D2) and (D3,D4,D5,D6)  are contained in the feedback loop of 2 IC’s. They create  what is commonly referred to as soft clipping.

D3, D4, D5, D6 are not in series they are two sets of 2 diodes in series, placed in parallel of each other with opposite polarity. giving symmetrical clipping.

I’m a big fan of Mosfet clipping like used in a zen drive or Barry’s Zenith or  NT Dumble tone. The old ODC circuit uses Mosfets for hard clipping.

Socket and see as they say.

Hope that helps

[Barry]

Yah, I obviously had a brain cramp while trying to answer too quickly. 😳
D7 and D8 are the hard clipping diodes in this circuit. Also much easier to mod.

Thanks brd

[brd]

I was about to modify my post to add some clarification, when I realized I contradicted Barry. I don’t like the terms hard and soft clipping, they are ambiguous. Germanium diodes give what some people call soft clipping too. Using a diode with a low Vf gives more or harder clipping than a diode with a higher Vf. D3 – D6 add the most clipping in this circuit, so Barry is not wrong by that definition, it just matters what you are trying to achieve.

No clipping is another popular mod and likely the easiest to do with just a switch.

Sorry for any confusion, I am not one of the Gurus here.

[Barry]

I agree! That said, D7 and D8 are easy to switch.

[X]

Ok, so if I want to change the diodes that would affect the sound of the distortion the most, should I swap D7-8, D3-6, D3-8, or D1-8? It sounds like D7-8 will probably have a large impact (right?) but will D1-2 or D3-6 even be noticeable if swapped?

[brd]

If you can tell us what you are trying to achieve it would be easier to give you some guidance.

As I mentioned, the forward voltage is what effects the signal. An average red LED has a forward voltage around 1.6 to 2.0 volts so any signal above the 1.6 to 2.0 volts will be clipped. The 1N4148 diodes called for D3-D6 have a Vf around 1V. They will clip more and therefore compress more and lower the signal volume. However putting 2 of them in series is additive for the Vf, so 2 of them in series will give you around 2V Vf.

If I haven’t made this complicated enough, the type of diode affects the clipping in how fast or slow the clipping turns on and off. This is why germanium diodes are said to have softer clipping. Diodes in an IC feedback loop have softer clipping because of the characteristics of the IC used.

The final twist when using multiple clipping stages is to consider placement . Using LED’s after a clipping stage with a low Vf will not do much unless the signal is amplified between them.

So simply put if you want more clipping and a more compressed sound lower the Vf, if you want less clipping and a louder more open sound raise the Vf or even eliminate the diodes.

There is still more to this magic and hopefully someone smarter than me will correct anything I got wrong, but I hope that helps

 

[X]

Fair point. I saw this video and already have a pedal themed around gold anyway, so it seemed kismet, and I like the sound. He explains the details around 1:16 and says to replace a set of hard clipping diodes with the pyrite using a wrap on one end and a cat whisker connection on the other. That seems easy enough, but this pedal uses more than just 2 diodes, so I’m trying to figure out how to best incorporate that into this pedal while also having an DT switch to select between stock mode or this alternative version.

[brd]

That video has been popping up in my feed for a few days, I’ve been ignoring it because I’ve tried Watlon’s $5 Dumble and it sounded like *ss. I watched through it thinking it was some April fools day joke, but a quick search showed it is actually possible. As fate would have it my wife is a hobby gemologist and she had a chunk of pyrite. So I ran out to the shop and grabbed my Fluke and some wire  and sure enough it seems to work. I got readings up to 1V. the whisker placement matters and I didn’t hear Walton mention what Vf he used or how he kept it stationary (maybe wax). You will want to switch the leads to be sure it gives the same reading in both directions for symmetrical clipping (or not).

Also keep in mind what I mentioned about the effect of Vf. The stock LED’s have a high Vf, going lower can drastically cut your volume. He also used a switch to change the input cap (C1) and a pot to vary the amount of signal getting to the pyrite diode (PD).

So back to your question,  D7 and D8 are where you want to put a switch for your PD. I would suggest using one of Barry’s DPDT boards and putting the LED’s on one side of the switch and run wires to your PD from the other. then connect the signal wires to either of the empty diode pads on the BE board, either D7 or D8.

I don’t think my wife will give up her Pyrite so there isn’t much chance I’ll get to try this unless she finds another one. Please let us know how it works for  you.

Best

 

[X]

I don’t have that, just the easy 3PDT board, so I guess I’ll need to order one. I may also need to get a switch someone b/c my only spare DPDT is an ON-OFF-ON. I really wish there was a slider switch I could use but it seems like none of them having spacing to fit this.

I’ll also need to consider how to mount it b/c I planned on keeping the switch internal. Maybe I’ll make a wood enclosure to hold it in place without shorting accidentally? Or maybe 3D print a box? As for keeping the PD in place, I was thinking a zip tie or even hot glue within its own enclosure. It shouldn’t get hot enough to melt glue or plastic, right?

Ok, so as for the wiring, I haven’t used a DPDT Wiring Board before. It seems simple enough, but I’m a bit rusty and I may be overthinking it, so I want to confirm a couple things:

1. Looking at the 4th pic in the example below, would the blue wire be the input and the purple is the out, or does it not matter?
2. If I use the top for the LEDs and the bottom for the PD, does it matter which row represents D7 and which is D8?
3. Similarly, does it matter which direction I have the LED going for each row as long and their positives are asymmetrical?
4. You said to run the signal wires to either D7 or D8. This seems like a very obvious question (but again, rusty), but I’ll need a jumper for whichever I don’t use in order to complete the circuit, right?
5. Then, b/c we don’t know the Vf of these, once installed I should power it on and check the VF from the input to the output with the switch in both directions to ensure the PD is not lower, right?
   • If it is lower, is there anything I should do internally to solve for this (like adding something else to the DPDT board), or just increase the volume or use a boost?

[brd]

I’m glad you mentioned the switch, you’ll want to use an on-off-on switch, that will give you a third option of no clipping in the middle position.

You will need an enclosure for the PD to keep it insulated. You don’t want it shorting to the enclosure (or anything). no worries about heat.

The blue and purple wire would be interchangeable for your application.

It does not matter which row you use as long as the leads for each diode are on opposite sides of the line printed on the board

since there are two identical diodes, it doesn’t matter which goes on any row. Use the flat spot on the rim of the LED’s to be sure they are set in opposite polarity. <span style=”text-decoration: underline;”>teaching moment</span> – For D7 and D8, each diode clips half of the AC signal, when both halves are clipped with the same diodes (and number of diodes) the signal is clipped equally or symmetrically. The PD apparently clips symmetrically on it’s own, that’s why you don’t need 2 of them.

connect the blue and purple wires to a round and square pad for either D7 or D8. The other diode pads on the BE board will be empty. Since those diodes are in parallel, using a jumper would create a path of no resistance to ground and you would lose all signal.

You can measure the Vf of your PD using a meter that has a diode check option with the diode out of the circuit. The meter will supply a small current to the diode and give you a Vf reading, That is what Waylon is demonstrating at 1:12 in the video. Any difference in Vf won’t matter unless you switch while you are playing.

I hope that helps

[Author]

Posts