Klein Bottle problem :(

[Masochist]

Yep how could I not notice that hulking cap haha!! I thought about doing the mods initially as when I saw Peters video I didn't even have the 9mm pots and switches soldered in yet, would have been the perfect time to do it really. But I figured that I didn't even know if the pedal worked yet! So yeah, I'll do some tests and make sure it all works and then I'll think about doing the mod.

Is the signal bleed etc really that bad? Cheers man.

[benny_profane]

I haven't placed a mouser order since the mod was announced, so I haven't done it yet. (Maybe EBK has.) The bleed is definitely there. It's faint, but if you're running some hot signals, it's high enough that it could mess with things. It's not a dealbreaker on the unit—it's terrific—but it is noticeable.

[EBK]

I view the mods as a fix of a defect rather than an improvement, if that makes sense.  It would bother me not to do the mods, but I haven't placed a parts order yet.

[Aentons]

I view the mods as a fix of a defect rather than an improvement, if that makes sense.  It would bother me not to do the mods, but I haven't placed a parts order yet.

Every Ibanez tube screamer that I've ever played has a bypass bleed issue. It's faint, but it's there. Crank the gain all the way up and take a listen with it off.

[Masochist]

Ok you've sold me! I will definitely do the mod I watched the video the day it came out and it's great that it can all be performed without having to remove the board. Opening that thing up again seems like a daunting task at this stage, so I think I'll give it a little while.

Good luck with your mods though, would love to hear how u guys get on!

[Masochist]

I'm shopping for parts for this mod.. seeing as I really only need the 10000uf cap and due to Mouser's expensive shipping to Australia I'm trying to find an alternative on RS. I found this one..

https://au.rs-online.com/mobile/p/family-id/7442029/

It looks pretty similar in size, a little shorter in length and it's life is 2000 hours compared to the Mouser one having 10000 hours. What do you guys think?

[EBK]

Could also make an op amp buffer daughter board to create a buffered Vref.  I'm debating whether to do this instead of buying a BFC. 

[Masochist]

Could also make an op amp buffer daughter board to create a buffered Vref.  I'm debating whether to do this instead of buying a BFC.

This sounds interesting although I have no idea what you're talking about! Could you explain what you mean? Are you thinking about making some kind of veroboard thing?

Do you think that cap I linked to matches the recommended one enough? I ended up just ordering it anyway. I think it cost me $6 inc postage so no big loss if I've made the wrong decision.

[EBK]

I need to look more closely at the mods and the schematic, but my understanding is that the bleedthrough is happening, at least partly, because the Vref is varying as the op amps draw current out of that node in proportion to the signals they are working on.  Peter's fix, that extraordinarily large cap, is a giant reservoir where that current can come from when the demand is high (and then the cap can be recharged as the current need swings the other way).  In this way, it basically filters the voltage fluctuation.  But, a more elegant way to do this (in my humble opinion) is to add a simple buffer to the Vref node.  I would consider doing this with a very tiny veroboard with a TL072 on it.  The op amp would take care of supplying the fluctuating current at a constant voltage.
Smaller and possibly even cheaper than the Capacitor-of-Unusual-Size solution.  I have plenty of veroboard scraps around, and I always have a spare op amp, so I may give it test sometime and report back. 

But, again, I need to look more closely at it all first.

[Masochist]

Awesome!! Sounds plausible but then again I know very little. I too have many spare TL072's and veroboard scraps. Please do keep me up to date. Would love not to have to replace this hulking cap after 2000/10k hours!

[EBK]

Here is what I've sketched up.  This would probably make the other resistor value swaps unnecessary.  Haven't looked into that extra resistor Peter attaches to the transistor yet though.

I've somewhat arbitrarily chosen 10k for my resistors in my schematic. Feel free to chose another value if you are low on those.

I haven't tested this, but I do plan to eventually.

[Masochist]

This is fantastic! Thanks so much for keeping me up to date! Can you tell me what the circle around one of the connections means at the bottom right of the vero drawing?

[EBK]

This is fantastic! Thanks so much for keeping me up to date! Can you tell me what the circle around one of the connections means at the bottom right of the vero drawing?

That's how I draw a resistor standing up vertically on the board.  Sorry for the confusion.

[Masochist]

Sorry I'm still a little confused.. I've attached a screenshot where I've circled the part in question. To the right of it I see the symbol for a resistor and to the right of the resistor I see the symbol for a bipolar cap but I thought a straight line meant simply a point to point connection with hookup wire? Sorry man I'm kinda new to all this, just trying to understand and hopefully learn something!

[EBK]

I may be the only person who draws it like this, so don't feel bad about being confused.  It is meant to graphically represent how this looks, with the circle being the resistor body viewed from above:


I've actually spent the past hour (more or less) building this board.  In my build, I opted to lay that resistor down flat, and I bent the leads a little funny.  The top lead of my ceramic cap is also moved up, but this is electrically the same (the rows are connected by the jumper to the left).

And, covered in some heat shrink: