Tyrian distortion squeeling

[ferdinandstrat]

Well, built it, sounds ok but it squeals like crazy. Maybe I should increase one of the 100pF caps?

 

[music6000]

My LEDs dont have a flat side but from what I understand the flat side is the kathode, I put both of them through the square holes.

Here is how your Clipping LED's should be mounted.
Check with Robert (PedalPCB), If yours are both reversed, It may still Clip the same?
From all the different Led's I have purchased, They all have a Flat machined at the base of the Plastic, That is the Cathode - Side.

 

[Robert]

Yes, as long as both clipping LEDs were installed using the same method it won't matter if they're both backwards.

Is what you're hearing electronic oscillation, or acoustic feedback? Does your guitar tone control / pickup switch have any effect on the squealing?
What about the direction you're facing with your guitar?

I just dimed the gain and volume direct into my audio interface (it gave my interface hell at that level, but no oscillation)....

Then I tried it into my Twin.... Realistically I can't crank the Twin up all the way because... well... it's a Twin... but no oscillation. My guitar does want to naturally feedback at higher volumes, but not in a bad way.

 

[ferdinandstrat]

Yes, as long as both clipping LEDs were installed using the same method it won't matter if they're both backwards.

Is what you're hearing electronic oscillation, or acoustic feedback? Does your guitar tone control / pickup switch have any effect on the squealing?
What about the direction you're facing with your guitar?

I just dimed the gain and volume direct into my audio interface (it gave my interface hell at that level, but no oscillation)....

Then I tried it into my Twin.... Realistically I can't crank the Twin up all the way because... well... it's a Twin... but no oscillation. My guitar does want to naturally feedback at higher volumes, but not in a bad way.

Its the same type of squealing that happened on the Brown Betty, I was capable of somewhat remedying it by increasing the 47pF(I think cap) in the feedback loop(compensation cap? Like in the RAT?). Its definitely electronic oscillation because adjusting certain parameters and the volume knob on my guitar increases or decreases the pitch, much like a Fuzz Factory, but it happens when I try to add volume or gain.

 

[temol]

I've build couple of Thermionic Distortion pedals, Brown Betty, Tyrian on a breadboard - no squealing at all, even of highest gain setting.
Is it inside the enclosure?

If you suspect that replacing the cap should fix the oscillation, then go for it.
Just add another 47p in paralell.
T.

 

[ferdinandstrat]

OK can someone please explain this phenomenon to me? I put an OD I built before the Tyrian to act as a clean boost/buffer and THE SQUEALING IS GONE. I heard that putting a buffer before such a pedal mends the situation and it DID, how?

 

[zgrav]

Does the squealing come back if you turn down the level of the signal going into your board, or if you turn down your guitar level?

And is the squealing gone using the OD even when you turn up the gain on your new pedal?

 

[Robert]

One possible explanation is that the input is picking up a stray signal (output signal, or some other internal signal path).

A buffer acts as a voltage follower and ensures that it's output (and in turn the input to your Tyrian circuit) closely matches its input, so whatever interference is being induced back into your Tyrian input is subdued by the buffering.

Fire up the Tyrian, set it so it's oscillating nice and loudly, and see if touching the input wires has any effect on the oscillation.

Also two questions:

1. What kind of guitar / pickups are you using?
2. What overdrive did you use in front of the Tyrian?

 

[ferdinandstrat]

One possible explanation is that the input is picking up a stray signal (output signal, or some other internal signal path).

A buffer acts as a voltage follower and ensures that it's output (and in turn the input to your Tyrian circuit) closely matches its input, so whatever interference is being induced back into your Tyrian input is subdued by the buffering.

Fire up the Tyrian, set it so it's oscillating nice and loudly, and see if touching the input wires has any effect on the oscillation.

Also two questions:

1. What kind of guitar / pickups are you using?
2. What overdrive did you use in front of the Tyrian?

I use an Ibanez SA960QM with Dimazio/Ibanez pickups, the overdrive was a Zendrive but the signal was even before by a spillter/mixer and the Zendrive.

 

[music6000]

Q. If someone asks me '' What value Resistor is this''?.
A. I'll just grab my DMM (Digital Multi Meter).
I have never bothered to try & learn the Coloured Bands (Try reading 1/8W Resistors).
Simply because I measure every Resistor I put in a Circuit, ie 10r = 10r, not 10k.
I measure every Capacitor, the Pots - Diodes, Transistors & LED's (Peak DCA55).
I always Print out an Enlarged picture of the PCB photo to confirm what I see on the actual PCB matches.
I highlight the component with a Marker Pen on the PCB photo as I load the PCB.
I believe this is a Good Practice so when it comes to Firing it up it minimizes a Faulty component.

Happy Soldering!
Cheers, music6000