Green Ringer Clone Help

[awgearhart]

Hello again,

I just finished soldering my Green Ringer clone using the schematic from TonePad (not using the PCB): http://www.tonepad.com/getFile.asp?id=90

It's fully functional, but the octave sound is too subtle for my liking. I only get a pronounced octave sound when I'm on my neck pickup and playing above the 12th fret. It also has a little bit of distortion that I could be fine with, but would be nice to be cleaner. I like the sound of this version from BYOC: https://www.youtube.com/watch?v=hnKxmy4TNsA&t=14s

I don't understand the whole 4.5V and 18V wiring scheme as seen in the BYOC docs: http://byocelectronics.com/octavemoduleschematic.pdf

I'd like to simplify re-doing my circuit, but I'm looking for suggestions to improve the octave sound and possibly lower the gain. One of the build reports on TonePad stated he replaced the 2N3906 with another 2N5088 to get a better octave sound...

Just looking for other's opinions, thanks!

[Mark Hammer]

You can improve the octaving by doing these two things:

1) Put a 10k pot and 2u2-4u7 cap in parallel with R4, negative cap lead going to ground.  This will allow you to vary/increase the gain of the input stage.

2) Put a back-to-back pair of silicon diodes in parallel with R10, and stick a 100-470R resistor between the diodes and the ground connection.  Sticking a 1000-3300pf cap in parallel with that will also help to remove annoying "fizz".

Because mod #1 will produce a volume boost, I like to convert R10 to a 47k log volume pot, to keep the levels balanced.

As with any octaving circuit, making sure the two complementary rectified half-waves are as equal as possible helps.  So if you can measure the forward voltage of the diodes, and can find two that are fairly close in forward voltage, that will improve things.

C1 should properly have a 1M terminating resistor to ground to avoid switch popping, and a small-ish value cap (470-1000pf) in parallel with that added resistor will further remove any annoying high frequencies that will "hide" the octave.

[Marcos - Munky]

I only get a pronounced octave sound when I'm on my neck pickup and playing above the 12th fret.

That's exactly how analog octave circuits works. Also, to get the octave more pronounced, a known "trick" is to roll the tone pot to zero (while playing above the 12th fret and with the neck pickup). That's most probably the setting for the video you've posted the link.

Adding gain before or after the octave (by using a fuzz or distortion) also makes the octave more pronounced.

[awgearhart]

Thanks for the input. Mark, in response to your advice, the components you call out (R4, R10, C1, etc.) are in reference to the BYOC PDF, correct?

The circuit I built is from TonePad... that PDF is here: http://www.tonepad.com/getFile.asp?id=90

Could I make the same adjustments as you mentioned with this circuit?

[awgearhart]

I also saw someone mention replacing the 2N3906 with a BS170. Again, any suggestions would be helpful.

[Mark Hammer]

Thanks for the input. Mark, in response to your advice, the components you call out (R4, R10, C1, etc.) are in reference to the BYOC PDF, correct?

The circuit I built is from TonePad... that PDF is here: http://www.tonepad.com/getFile.asp?id=90

Could I make the same adjustments as you mentioned with this circuit?

Yes.  It is the identical circuit, but for a change in the NPN transistors used, and the inclusion of the terminating resistor on the input cap that was missing in the BYOC diagram.

[awgearhart]

I have a C10k pot, is that what you mean in reference to #1?

In reference to #2, I'll post a picture of what I think you mean. Is it correct?

[Mark Hammer]

I've redrawn the Tonepad schematic, with the added parts in their respective locations on the input, output, and at emitter of Q1.  I've also done my best to reduce it in size.  I like to be able to print circuit drawings out in landscape, and often shrinking them in some ways allows for the image to fill up the page nicely.  So apologies to Francisco, and traditionalists.  I hope everything is recognizable.  Treat the values of the additional parts as reasoned suggestions, rather than gospel.

[awgearhart]

This helps a lot. Thank you for the redraw!

Since I have the C10k pot, I should be wiring the pot reverse to an A10k, correct?

[Mark Hammer]

Just wire it so that turning it clockwise reduces the resistance.

[awgearhart]

UPDATE:

I added a 1n cap parallel to the input resistor (2.2M), replaced the diodes in the original to Germanium 1N34A's, added the back-to-back diodes (1N914) with a ground terminating resistor (470R) and a 1n cap in parallel with the output, and removed the 47k resistor to match the output level when the pedal is bypassed.

I did not want to have any pots to control gain/volume despite versatility. I desired simplicity.

Pedal sounds great, especially with tone rolled off (almost sounds like a synth).

Thank you Mark for your updated schematic!

[Mark Hammer]

Excellent!  I was pleasantly surprised by how much better it sounded, relative to the stock circuit.