JMK paralizer issue

[Sophia2001]

Hi all,

I'm running into a problem. I made a JMK paralyzer. One Send goes to a Big Muff circuit, the other Send goes to a Woolly Mammoth circuit. The Paralyzer, Big Muff and Woolly Mammoth are together in one enclosure.

When I turn the blend knob of the paralyzer to one side I hear the Big Muff. When I turn the blend knob to the other side, the signal is gone. The Woolly Mammoth doesn't work together with the Paralyzer.

This is what I have tried so far:
- Woolly Mammoth circuit without Paralyzer (direct input/output) Works fine, no problems. In other words, the Woolly Mammoth is doing well.
-The Big Muff and Woolly Mammoth reversed. Same problem. Blend knob is reversed in function obviously.
- The Send and Return of the Paralyzer are directly connected, clean signal comes through well. In other words, the Paralyzer is doing well.

Anyone?
Sophia 

Paralyzer:



Big Muff:



Woolly Mammoth:

[antonis]

Try to replace Woolly Mammoth output pot with another of 100k value..

(only if you're sure for your correct wiring..)

[ElectricDruid]

What's the point of the two 1M resistors to ground on the inputs here?

They're not for bias, since they go to ground, and it's an inverting op-amp set-up anyway, so the bias is on the +ve input (Vb, like we'd expect). And it's not for discharging the 1u cap, since there's always a path to do that from the cap through 15K to the 10K pot and to ground.

I don't think they're necessarily the problem, but I'd like to understand what the person who designed this thought they were for, because I don't get it.

The problem is more likely the relatively low input impedance of the blend stage. It's only 30K before you even take the parallel effect of the blend pot into account, which lowers it even further.

[Sophia2001]

Try to replace Woolly Mammoth output pot with another of 100k value..

Thanks for the help. Unfortunately it did not solve the problem. I do get more signal now but it sounds different, flattened? less output? If I connect directly to the input/output of the Woolly Mammoth the effect is much better in quality.

The problem is more likely the relatively low input impedance of the blend stage. It's only 30K before you even take the parallel effect of the blend pot into account, which lowers it even further.

Any suggestions ElectricDruid how to improve this?

Thanks,
Sophia

[antonis]

I do get more signal now but it sounds different, flattened? less output? If I connect directly to the input/output of the Woolly Mammoth the effect is much better in quality.

That's because Out pot low value interacts with EQ values..

As for Tom's remark, make R4 and R7 much bigger..
(and get rid of R3 & R8, although they do no harm..)

P.S.
Your issue might be more complex than it firstly appears..
Additionally to what Tom said about impedances, there are also unequal RC phase shifts between the effects..

[Krystal]

I don't know much but, don't Fuzz Face type fuzzes (such as the woolly mammoth) usually sound weak after a buffer. There are various tricks people use to improve the circuit's input impedance that might be helpful.

[Sophia2001]

Your issue might be more complex than it firstly appears..
Additionally to what Tom said about impedances, there are also unequal RC phase shifts between the effects..

Maybe a silly question, but the JMK Paralyzer is sold in such a way that it should work without any problems. I have made no changes to all three schematics. So it is actually strange that I experience buffer/phase shift problems. In other words, the JMK Paralyzer is actually a product that remains to be seen whether it will work for your combined effects?

Is there an alternative available to easily combine two effects with a blend knob?

Thanks!
Sophia 

[antonis]

Did you try to make R4 & R7 much bigger..??

It might also be needed to raise R11 value or BLEND pot one..

I'd proceed to make R4=R7=150k and BLEND pot = 100k..

but the JMK Paralyzer is sold in such a way that it should work without any problems.

As it is, only with effects of low enough output impedances..
(with either output buffers or low value Collector resistors..)

[Sophia2001]

I'd proceed to make R4=R7=150k and BLEND pot = 100k..

Thanks for your advice and help Antonis!

Changed R4 and R7 to 220k + 10k blend pot = same problem
Changed R4 and R7 to 220k + changed blend pot to 100k = same problem

150k was not available so I opted for 220k. So this didn't help... Unfortunately

Sophia 

[antonis]

OK.. Last try before extra buffers implemention..

Retain R4 & R7 original values and make Blend pot 100k ..

[ElectricDruid]

OK.. Last try before extra buffers implemention..

Retain R4 & R7 original values and make Blend pot 100k ..

How does that help? All it does is change the blend curve, doesn't it?

I think Krystal has a point - the problem might be the buffer *in front of* the fuzz, instead of the impedance after it. Or it could be like you proposed - that the two circuits have phase shifts that make them incompatible.

[Sophia2001]

OK.. Last try before extra buffers implemention..

Retain R4 & R7 original values and make Blend pot 100k ..

Tried it but no luck. Any other suggestions Antonis? Swap the JMK Paralyzer for another blend?

Sophia 

[Matthew Sanford]

If Woolley being like a Fuzz Face is the issue, have you tried putting the signal on that side of the JMK straight to the send instead of the input buffer? Or set up the buffer by itself before the effect to see if it's the issue, then if adjustments there can make it work? I think Krystal is on to something there

[antonis]

A buffer in front of a fuzz definitely alters its character..
It doesn't turn it into a dead silent effect..

@Sophia: Could you plz try Paralyzer without Big Muff in two options..??
1. S-2T <-> R-2T open
2. S-2T <-> R-2T short

[Sophia2001]

If Woolley being like a Fuzz Face is the issue, have you tried putting the signal on that side of the JMK straight to the send instead of the input buffer? Or set up the buffer by itself before the effect to see if it's the issue, then if adjustments there can make it work? I think Krystal is on to something there

Sorry, but my knowledge about circuits and buffers is a lot more limited than yours. Although I learn a lot from this great forum! I can't quite follow your suggestion. Would it be possible to make a simple MS Paint drawing of what you mean with the above images I posted? In my first post I added the three circuits.

A buffer in front of a fuzz definitely alters its character..
It doesn't turn it into a dead silent effect..

@Sophia: Could you plz try Paralyzer without Big Muff in two options..??
1. S-2T <-> R-2T open
2. S-2T <-> R-2T short

Thanks again Antonis. I have tried both suggestions but I notice no effect. When S-2T <-> R-2T is short I get a nice clean sound on one side of the blend. The other side of the blend is the Woolly Mammoth but still very low in volume and poor quality.

Sophia 

[antonis]

I think Matthew suggests to omitt IC2_A..

What will happen with impedances huge difference between Woollymammoth and IC2_B, it's beyond my imagination...

[Krystal]

Well of course that certainly wouldn't do as a solution to the problem, but maybe switching out the Big Muff for a minute and testing the Woolly Mammoth with and without the input buffer (IC2_A) could rule out the input buffer as being the cause of the issue.

[Matthew Sanford]

That was my thought. Not necessarily a solution, but just to see if the buffer before the Woolley is causing issues.

[Sophia2001]

That was my thought. Not necessarily a solution, but just to see if the buffer before the Woolley is causing issues.

Update:



This works!

My knowledge is limited so this still raises some questions for me:
1) Why is this not a solution like Matthew and Kristal mention? In other words what is not good/neat about this solution?
2) Have I made the connection to S1 in the right place?

Sophia 

[Matthew Sanford]

I think the worry was input impedance mismatch that "could" cause issues, but if it works, it works! I think you can take it from where you marked. Is it pretty balanced between the two effects?