Adding Split n Blend to a Big Muff - Help required

[Minto]

Hello there! I want to add a split n blend circuit to my Black Russian Big Muff (small box) and I'm having some real difficulty wiring the thing up. The pedal has been modified for a 3DPT switch. It should be straight forward but I just can't get it to work! Could someone please help me out and complete my very childish diagram? It would be greatly appreciated, and would stop me from tearing my hair out!
Thank you!

[GibsonGM]

Hi Minto, and welcome...

Do you have any  more info on the splitter/blender you've got there?  Is this a drawing you made, or did you buy the thing and they gave you this? etc etc.    Need more info.

A schematic of the splitter/blend would be great      Not a hard thing to figure out, but you kinda want to be sure that what you're telling someone to do is what they actually designed the thing to do!  ha ha

[Minto]

Thanks for the welcome!

This is the splitter I have built: http://effectslayouts.blogspot.co.uk/2015/12/split-n-blend.html

I'm fairly sure I've now got it wired correctly, but when the 100k pot is turned all the way to Dry, there is still some fuzz in the signal...so I guess something is wrong somewhere along the lines. Is there a more suitable blend circuit?

[Snufkinoob]

I'm going to try IvIark's mini blend circuit on a super fuzz if that's any help.




I'd have thought that Input/send would go to the fx circuit, and return would be from fx out.

[chuckd666]

Thanks for the welcome!

This is the splitter I have built: http://effectslayouts.blogspot.co.uk/2015/12/split-n-blend.html

I'm fairly sure I've now got it wired correctly, but when the 100k pot is turned all the way to Dry, there is still some fuzz in the signal...so I guess something is wrong somewhere along the lines. Is there a more suitable blend circuit?

Maybe read over the directions again in the layout. The diagram you have drawn looks wrong.

"Effect In" on your 3PDT goes to the "In" on the Split N Blend.
"Send" on the Split N Blend goes to the "In" on your muff board.
"Out" on your muff goes to Blend 3.
Blend 2 goes to your "Effect Out" on the 3PDT.

[Minto]

Thanks for the welcome!

This is the splitter I have built: http://effectslayouts.blogspot.co.uk/2015/12/split-n-blend.html

I'm fairly sure I've now got it wired correctly, but when the 100k pot is turned all the way to Dry, there is still some fuzz in the signal...so I guess something is wrong somewhere along the lines. Is there a more suitable blend circuit?

Maybe read over the directions again in the layout. The diagram you have drawn looks wrong.

"Effect In" on your 3PDT goes to the "In" on the Split N Blend.
"Send" on the Split N Blend goes to the "In" on your muff board.
"Out" on your muff goes to Blend 3.
Blend 2 goes to your "Effect Out" on the 3PDT.

Yeah that's how I have it wired right now but the fuzz still comes through when the blend knob is on full dry.

[GibsonGM]

Hmm, well, chuck's right - go over the wiring again (you will get used to doing this all the time, ha ha....) - mostly we encounter build errors that cause these bugs.  Could be a short on the switch, or on your blend board, etc.   

When you're sure YOU didn't make an error, why don't you re-draw how you have it set up, and we'll look again...

[duck_arse]

minto - on your little buffer board, both "send" and "blend 1" are outputs. and, I'm not sure if biasing 2 jfet gates with a single resistor is a legal method.

[edit :] further thinking - I think that circuit is probably wrong. once the input has been buffered by one of the two source followers, you only need a resistor splitter from the source to each whatever. otherwise, put the resistor splitter at the input, and then run two completely seperate (as in a gate resistor, maybe a blocking cap each) source followers. an expert might along soon to clear it up.

[Minto]

minto - on your little buffer board, both "send" and "blend 1" are outputs. and, I'm not sure if biasing 2 jfet gates with a single resistor is a legal method.

[edit :] further thinking - I think that circuit is probably wrong. once the input has been buffered by one of the two source followers, you only need a resistor splitter from the source to each whatever. otherwise, put the resistor splitter at the input, and then run two completely seperate (as in a gate resistor, maybe a blocking cap each) source followers. an expert might along soon to clear it up.

I'm fairly sure the circuit works because people have verified it....but perhaps it doesn't sit right with a Big Muff pedal?

[Snufkinoob]

Didn't notice this one ...



Pretty much the same other than the pot lugs are swapped. Not idea how that might affect it in a detrimental way. Are you using a linear (B) pot? If it's log (A) maybe it's bunching the singal up at one end, causing something in the fx circuit to be retained? Or maybe you accidentally put in a wrong value resistor or cap somewhere?



And to slightly hijack the thread, how would the in/send be wired up for this mini blend circuit? Would it go to the input at the bypass switch, the fx input or both?

[ashcat_lt]

With this sort of simple passive mixer, it's can be really difficult to avoid bleed, especially when you've got a heavily boosted and clipped signal on one side.

If you use a bigger pot, you'll get more seperation at the extreme ends, at the expense of perhaps more "touchy" taper and/or more overall attenuation in the center position.

Better is to use an actual blend pot - a dual gang pot wired as an actual voltage divider for each source.  You have to wire the two sections opposite each other so one goes up while the other goes down and "backwards" with the source to the wiper and one of the outside lugs as the output.  That, then, is going to short the output of whichever is turned all the way down to ground, which might not make it particularly happy, but otherwise it'll just go completely silent at either end, which is not at all what you want. 

Better still is to use that dual-gang pot, wired forwards (like normal, wiper as output) but then buffer each wiper before combining them through mixing resistors.

Edit - Or, you know, when you don't want to hear the distortion, stomp the bypass switch. 

[duck_arse]

minto, I'm not saying it doesn't or won't work as shown, I'm just saying I'm not sure it's technically correct.

[AlexC]

If you use a 2N5457 you'll be fine with the mini Jfet blend board on tagboardfx. The J201 in that position doesn't work as it should. Once swapped over, there's no fuzz bleed used in conjunction with a big muff style fuzz.

[Renegadrian]

Snufkinoob
I used that IvIark's mini blend circuit on a muff and it's super!!!