Aion Radian (Rangemaster clone) - Noise Issues

[psb962]

Can I just add that this pedal is well worth it. Not only does it bring that 'top boost' chime, but what it does to the harmonics in the upper registers is nothing short of magic. Pure rock and roll!

[psb962]

Surprisingly (or not) a lot of pedal circuits do incorporate some basic EMC provisions only because people blindly copy what others have done. This includes such things as adding a small resistor in series with the input and a small value capacitor to ground to help filter any RF ingress or egress via the input connection. Also adding a suitable Miller capacitor to a high gain transistor stage or an op amp to limit the high end gain and kill off any parasitic oscillations in the RF spectrum. ....

I've noticed that other boosts have something like a 10k resistor on the input in the signal path. Is this something I should try with this build to noise-proof it a little? My options are limited as its a kit PCB build, but fitting a 10k in the signal path shouldnt be too hard.

[FSFX]

I've noticed that other boosts have something like a 10k resistor on the input in the signal path. Is this something I should try

Because of the very low input impedance of the Rangemaster circuit then a 10k resistor would probably be a bit on the large size and would attenuate the input signal quite a bit. I would try using something like a 1k resistor followed by a 470pF or 1nF capacitor to ground to form a lowpass filter. The cutoff frequency of that is way above the audio range but will reduce any RF signals from broadcast stations and cellphones.

As regards the use of ferrite beads that some often mention, for information, I tested a few with different numbers of turns and this is the inductances I read on a Peak LCR45 tester. The straight wire is just for reference. You can see that the inductance is very low and so their use would likely only filter out very high frequency RF signals.
   

[psb962]

I started getting loud crackling sounds so opened the pedal up again as clearly there was still a bad joint.

Redid all the soldering again.

I then 'rocked it out of the box' - which is easy to do with Aion's style of offboard wiring. However, I spent over an hour trying to debug a 'signal when off but no signal when on' problem before I realized that the pedal works best if you plug the input into the Input, and the output into the Output.

Another lesson learned from build #1....

[psb962]

Calling the Rangemaster gurus: if I was to switch out the PNP Ge transistor in my pedal for a silicon PNP transistor (assuming I have enough bias adjustment to to bias it) would that reduce the noise inherent in this circuit? Or would it be a waste of time as the Ge 'mojo' would be gone?

[aion]

Calling the Rangemaster gurus: if I was to switch out the PNP Ge transistor in my pedal for a silicon PNP transistor (assuming I have enough bias adjustment to to bias it) would that reduce the noise inherent in this circuit? Or would it be a waste of time as the Ge 'mojo' would be gone?

There are silicon Rangemasters—the Catalinbread Naga Viper is one, but NPN rather than PNP—but the circuit changes are relatively extensive. All of the sound comes from a single overdriven germanium transistor, so it'd be similar to swapping out single coils for humbuckers on a Strat. It may be more to your liking afterward, but it's not a true Strat anymore except in appearance.

[ElectricDruid]

However, I spent over an hour trying to debug a 'signal when off but no signal when on' problem before I realized that the pedal works best if you plug the input into the Input, and the output into the Output.

Awww, gawd. The number of times I've done that when fiddling with a pedal with the back off - when it's *upside down* the input and output are *reversed*, so if you plug into it the same way you did when you were testing it with the back on just a minute ago, it won't work! Gagh! Human brains are weird. Once we get an idea in there (which is hard enough in itself!) it's damn impossible to dislodge it!

[psb962]

Calling the Rangemaster gurus: if I was to switch out the PNP Ge transistor in my pedal for a silicon PNP transistor (assuming I have enough bias adjustment to to bias it) would that reduce the noise inherent in this circuit? Or would it be a waste of time as the Ge 'mojo' would be gone?

There are silicon Rangemasters—the Catalinbread Naga Viper is one, but NPN rather than PNP—but the circuit changes are relatively extensive. All of the sound comes from a single overdriven germanium transistor, so it'd be similar to swapping out single coils for humbuckers on a Strat. It may be more to your liking afterward, but it's not a true Strat anymore except in appearance.

Ok then the Ge stays. I might try rolling Ge transistors instead. The one in the kit is a MP21D. Any suggestions for other Ge transistors that you might have tried, and work well in your kit?

[psb962]

Update: what I have learned about Ge treble boosters after a few months using one is as follows:

1. You must run it direct from the guitar, not after any other pedals, not even a tuner.

2. You have to use the guitar volume knob to tame the high treble harmonics as the circuit has no low pass filter at all.

3. Circuit is prone to noise, so stay away from internet routers, neon lights, etc.

4. You must run it into a dirty amp, absolutely not a clean amp.

If you do all the above then these are killer pedals with pure visceral rock n roll tone.