Blue Shoe Gai Pan Distortion

[droneshotfpv]

I biased mine a little under 9V, I'll have to try the 11.11

Did you ever try a different BIAS voltage? What did you think if you did? I just built mine, and at first I screwed up with the BIAS. Instead of reference ground in the circuit for setting the drain, I used the 3rd leg as a grounding point. The results were terrible. However, when using the sleeve ground of the input / output jacks, and then set the Drain voltage to 11.11v, it sounded WAY better.. I am going to fool around with it this weekend to test a few other voltages, as well as using a 7660s in place of the 1044MAX charge pump, and then see what results I get.

@daeg , in your illustration above, which was extremely handy for me BTW, so thank you.. you said "
JHS probably biases right at Vd=0.5*Vss (9v) like in the Superbolt, but this just sounds sweeter, albeit a little lower gain." So, in this reference, were you stating that the Vd in this example is = to 4.5v, then add the formula above for 0.7*|Vp| (in my case, that Vp = 0.539 as my J201's read 0.77 for all 3 (from Stewmac)? So essentially, in my case, that would be a BIAS setting of 5.039v? I have not tried it, but if that was what was suggested as per what JHS sets, I might try it and see what it's like as well.

For me, @11.11v , the PUSH control is stupid loud (in a good way) but forces crazy clipping immediately. I have also noticed the SWEEP knob and MID control knob have interesting effects on the circuit. a lot of MIDS turns the volume up even louder (while increasing MIDS) and the sweep can make it REALLY muddy all the way to the left. Tone control is also one that seems to NEED to be set PER whatever you dial in, no setting it and forgetting it where it sounds good for one dialed in sound, I seem to need to change it anytime I make a chage to gain, MIDS, sweep and PUSH, or else it gets kinda muddy / sounding like I rolled off my TONE control on my guitar.

Any info anyone has or suggestions to try to get the BEST sound, I am all ears. I will be tweaking this weekend for sure!

 

[Barry]

Did you ever try a different BIAS voltage? What did you think if you did? I just built mine, and at first I screwed up with the BIAS. Instead of reference ground in the circuit for setting the drain, I used the 3rd leg as a grounding point. The results were terrible. However, when using the sleeve ground of the input / output jacks, and then set the Drain voltage to 11.11v, it sounded WAY better.. I am going to fool around with it this weekend to test a few other voltages, as well as using a 7660s in place of the 1044MAX charge pump, and then see what results I get.

@daeg , in your illustration above, which was extremely handy for me BTW, so thank you.. you said "
JHS probably biases right at Vd=0.5*Vss (9v) like in the Superbolt, but this just sounds sweeter, albeit a little lower gain." So, in this reference, were you stating that the Vd in this example is = to 4.5v, then add the formula above for 0.7*|Vp| (in my case, that Vp = 0.539 as my J201's read 0.77 for all 3 (from Stewmac)? So essentially, in my case, that would be a BIAS setting of 5.039v? I have not tried it, but if that was what was suggested as per what JHS sets, I might try it and see what it's like as well.

For me, @11.11v , the PUSH control is stupid loud (in a good way) but forces crazy clipping immediately. I have also noticed the SWEEP knob and MID control knob have interesting effects on the circuit. a lot of MIDS turns the volume up even louder (while increasing MIDS) and the sweep can make it REALLY muddy all the way to the left. Tone control is also one that seems to NEED to be set PER whatever you dial in, no setting it and forgetting it where it sounds good for one dialed in sound, I seem to need to change it anytime I make a chage to gain, MIDS, sweep and PUSH, or else it gets kinda muddy / sounding like I rolled off my TONE control on my guitar.

Any info anyone has or suggestions to try to get the BEST sound, I am all ears. I will be tweaking this weekend for sure!

No I have not gotten around to playing with the bias

 

[droneshotfpv]

No I have not gotten around to playing with the bias

So I finally got some time this weekend to fool around with the JFET bias on this build. At first I calculated the output voltage coming from my Charge pump. What I was seeing was 17.6v total output, so 8.80v was the split. I biased the JFETS @8.80 volts, and it sounded "ok" but had SERIOUS mud issues in a variety of settings. I do believe I could have tweaked hardcore and found an enjoyable sound, but I just didn't care much for what I was able to dial in "quickly" and didn't have a ton of time to dedicate, so I chocked it up to "not the best voltage" and moved on.

I then biased to 9.3v, results were better, but still not where I wanted to leave it, see above for SMILAR (but somewhat better) results.

I moved on to 10.5v... Now we're getting to a better spot. Things were a lot EASIER to dial in, and I didn't feel that tweaking the hell out of it was as necessary to find an useable sound that I personally liked. Still, I figured better could be achieved, so.....

11.11v.. This seems to be the sweet spot, at least for my build. the 3rd JFET on mine has an issue where it doesn't like to stay put when I zero in a voltage. Example, set it to 11.11v, but remove the screwdriver gently, and it drops to 11.03v, try again, it goes to 11.19v, etc. I finally got it to settle and stay at around 11.09v, which is close enough for me.. the other 3 are dead on 11.11v.
THIS setting is where it's at for me. The muddy / not so clear low end gets brighter and more audible.. It sounds less like a janky fuzz (the other voltages, that is the best way to describe it.. janky fuzz (trademark haha), even with PUSH as low as it could be, and still produce sound, those other voltages were just mud pies) and more like a distortion / OD with balls.
PUSH control at these voltages seems intense (lets be honest, it's intense no matter what, just more so here), and this pedal is a different creature than what I am used to. As others have stated, the MIDS when cranked, really turn up the volume, and every change on this pedals requires you to re-tweak literally every sans volume. I will put this thing through more of a test once I have a greater amount of time to fool with it all, but I can honestly say, to my ears anyway, that 11.11v BIAS on the J201's works best for my build / ears. I encourage others who have this pedal to at least try the same, unless you tweaked it by ear and love what you have already of course!

 

[fig]

11.11v.. This seems to be the sweet spot, at least for my build.

Outstanding! I've been using that same method (adjusting applied voltage) for builds requiring biasing. It really brings everything together. A little trickier without a charge pump mind you.

 

[sticky1138]

Just finished this build. I tried biasing mine to 9V, didn't care for it, then 11.11V, but that wasn't cutting it for me either.

I actually own the PG-14, so I put the two through a looper and biased by ear. I have it pretty close to the original, but I was able to tighten it up even more so the drive is less saggy and fuzz-like, and more focused at higher gain settings.

I ended up with these voltages, from left to right: 14.86 / 13.01 / 6.43

I'd definitely recommend biasing by ear. It's a great pedal, and I'm surprised by how well the mid EQ works. As others have mentioned, it's kind of tricky to dial in, but once you do, there are some unique tones to be had.

 

[Chuck D. Bones]

Can you measure the bias points on the original?

 

[sticky1138]

Sure, on the original I got:

9.51 / 7.64 / 9.75

 

[giovanni]

Was just curious, mine crackled and popped like crazy. Swapped it out with a TL072 and it cleared right up.

Wasn't sure if it was just a bad opamp (if so it'll be the first defective part I've ever gotten from Tayda) or if it wasn't a legit part.

Probably was just a defect.... After hundreds of thousands of parts ordered over the years for pennies, I can't really complain about one bad opamp.

Statistics are a b$&@*h.

 

[Chuck D. Bones]

It was probably a bad solder joint.

 

[daeg]

It's been forever since I've thought about this circuit, but I think we learned a mid-shaper (active sweepable bandpass-filter) in front of a flat-ish overdrive is an incredible thing.

This pedal fell off my board, mainly because I find the 'Push' control annoying, but a Varioboost into the Hotcake has remained. Same idea.

 

[daeg]

For me, @11.11v , the PUSH control is stupid loud (in a good way) but forces crazy clipping immediately.

That doesn't sound right. I seem to recall higher voltages at the drain lowers the gain, and vice versa.

The idea from RoG was you sacrifice the high gain of biasing at the (1/2)Vcc, but you set the transistor in a state where it is going to clip more like a triode / tube.

It's been so long I hardly remember though.

 

[Chuck D. Bones]

It's not the higher drain voltage that reduces the gain, it's the smaller drain resistor that reduces the gain. With FETs, it's better to reduce the drain current than to reduce the drain resistor because you give up less gain that way.