# Blue Shoe Gai Pan Distortion



## K Pedals (Mar 24, 2020)

This one sounds pretty cool...
Not sure if I biased it right...
Just did 4.5v on all of em...
sounds pretty good...


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## Robert (Mar 24, 2020)

I biased the prototype 100% by ear, never even broke out the DMM....

I just adjusted the trims back and forth one at a time and listened for the most full and open sound.  

Just curious, did you get your NE5532 from Tayda?


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## K Pedals (Mar 24, 2020)

Robert said:


> I biased the prototype 100% by ear, never even broke out the DMM....
> 
> I just adjusted the trims back and forth one at a time and listened for the most full and open sound.
> 
> Just curious, did you get your NE5532 from Tayda?


Cool!!!
Yeah these didn’t seem to be as picky as the son of ben ones... 
I probably did get it from Tayda but it could’ve been mouser...
I can’t really remember...
I’m ordering so many parts now-a-days it’s hard to keep up...


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## Robert (Mar 24, 2020)

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.


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## K Pedals (Mar 24, 2020)

Robert said:


> 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.


Yeah I love Tayda... 
I know I’ve heard some people don’t ... but I order a lot of stuff from them... I’ve started realizing some of their transistors seem like they’ve been picked through and some ICs (mainly tc1044) aren’t too good... and so now I get my transistors and caps and ICs from mouser 
but all in all I love Tayda...


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## PKRPedals (Mar 24, 2020)

What about the build docs for this one? Mine will be here tomorrow.


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## K Pedals (Mar 24, 2020)

Pots
A500k x2
B10k x2
A50k
B100k Dual
*resistors*
120k
330r
22k x2
3.3k x2
1m x2
10k x3
1.5k
470k x3
4.7k x4
12k x2
6.8k
5.6k x2
2.7k
*Electrolytic’s*
100u
4.7u x2
10u x3
47u
47p x2
470p x2
*Transistors *
J201 x3
*IC*
TC1044
TL072
NE5532
*Diodes*
1N5817
idk about the film caps cause I already soldered it


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## Chuck D. Bones (Mar 24, 2020)

Beautiful!  Gloss black box is very classy.  If it sounds good, you biased it right.  Is that a "gold" switch from BLMS?  I picked up a few on my last order.  Now for the $64,000 question:
Does it make you sound like Paul Gilbert?


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## K Pedals (Mar 24, 2020)

Chuck D. Bones said:


> Beautiful!  Gloss black box is very classy.  If it sounds good, you biased it right.  It that a "gold" switch from BLMS?  I picked up a few on my last order.  Now for the $64,000 question:
> Does it make you sound like Paul Gilbert?


I still haven’t tried one of those gold ones...
Maybe if I had $64,000 worth of lessons.. lol


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## music6000 (Mar 25, 2020)

K Pedals said:


> This one sounds pretty cool...
> Not sure if I biased it right...
> Just did 4.5v on all of em...
> sounds pretty good...


With that Powder Coat, It just squeezes in!
Are they NOS J201's ?

Very Tidy Build!


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## K Pedals (Mar 25, 2020)

music6000 said:


> With that Powder Coat, It just squeezes in!
> Are they NOS J201's ?
> 
> Very Tidy Build!


Thanks man
2n5457’s


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## Mourguitars (Mar 25, 2020)

Picture perfect !

Looks awesome KP

Mike


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## K Pedals (Mar 25, 2020)

Mourguitars said:


> Picture perfect !
> 
> Looks awesome KP
> 
> Mike


Thanks Mike!¡
Fixing to start working on the General Tso’s compressor...


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## daeg (Mar 29, 2020)

Robert said:


> Just curious, did you get your NE5532 from Tayda?



I built one using a NE5532 from Tayda. Sounds great.


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## daeg (Mar 29, 2020)

If anyone else is building one, I'd recommend trying out biasing using RunOffGroove 'Triode Emulation' formula.

A closer look at the Fetzer Valve




Vcc is supply voltage -- The 1044 puts the supply voltage (from a typical 1-spot supply) up to 17.55.
Vp is the pinchoff voltage of the JFET -- RoG measured a handful of J201's and found the average to be -0.83v.

So in most cases, the drain-voltage (Vd) to give the J201's the most 'tube-like' distribution of harmonics would be *11.11v*. JHS probably biases right at Vd=0.5*Vss (9v) like in the Superbolt, but this just sounds sweeter, albeit a little lower gain.


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## Barry (Mar 29, 2020)

Nice build!


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## Barry (Oct 4, 2020)

daeg said:


> If anyone else is building one, I'd recommend trying out biasing using RunOffGroove 'Triode Emulation' formula.
> 
> A closer look at the Fetzer Valve
> View attachment 3697
> ...


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


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## HamishR (Oct 5, 2020)

Now _that's_ how to do the wiring.  So neat.


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## Dali (Oct 5, 2020)

HamishR said:


> Now _that's_ how to do the wiring.  So neat.


I think the yellow wire here is not straight enough...


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## HamishR (Oct 5, 2020)

Well I noticed that too but didn't want to appear too harsh.  I was wondering about how mauve ground wiring might affect the sound. Does a ground know it's a ground when it's mauve?

I don't know about you guys but these are the things which keep me awake at night.


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## droneshotfpv (May 15, 2021)

Barry said:


> 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!


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## Barry (May 15, 2021)

droneshotfpv said:


> 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.
> ...


No I have not gotten around to playing with the bias


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## droneshotfpv (Jun 6, 2021)

Barry said:


> 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!


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## fig (Jun 6, 2021)

droneshotfpv said:


> 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.


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## sticky1138 (Apr 12, 2022)

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.


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## Chuck D. Bones (Apr 12, 2022)

Can you measure the bias points on the original?


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## sticky1138 (Apr 12, 2022)

Sure, on the original I got:

9.51 / 7.64 / 9.75


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## giovanni (Apr 12, 2022)

Robert said:


> 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.


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## Chuck D. Bones (Apr 12, 2022)

It was probably a bad solder joint.


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## daeg (Apr 14, 2022)

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.


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## daeg (Apr 14, 2022)

droneshotfpv said:


> 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.


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## Chuck D. Bones (Apr 14, 2022)

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.


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