Green ringer is awesome.

[petemoore]

But it's a bit 'stingy' on the output, just like the first one I did and never figured out...
 This time though it seems obvious that increasing value of the resistor to ground, the 47k [which I already made a 56k] will increase output.
 Since this is an emitter follower, would I be correct in assuming that I can increase this R value signifigantly without upsetting the bias or function of the previous portion of the ckt?
 Right now I've got Ge's in Q2 PNP and Q3 NPN, and I like them there.
 I'm definitely glad I put the trimpot on Q2's C, for biasing different transistors and big variances in tone.

[Mark Hammer]

Over the summer I had a visit from JC Maillet.  We sampled a variety of his and my pedals and guitars, chatted at length about octave-up units, and came to a number of conclusions.  He's far more the mathematician than I will ever be, so he can explain it better (or maybe worse :wink:), but the gist of it is that under certain circumstances, the standard phase-splitter-with-a-diode octave-up unit, like the Fender Blender, Foxx Tone Machine, Ampeg Scrambler, and Green Ringer, will act like a ring modulator.  This seems to be most especially true when bending notes ever so slightly so that it seems to "beat" against itself.  Since there is only one signal, like any 4-quadrant multiplier where you modulate it with itself, you get sum and difference, which can be an octave up AND an octave down in some instances.  This is why, even though it is an octave-up unit, the Green Ringer is titled a Green Ringer.

FWIW, I put together an Ampeg Scrambler this weekend, with 1N457 diodes courtesy of Mike Irwin, and MPSA14 transistors.  It provides a less focussed tone than the FTM and other units, but also yields something that at times seems to introduce undertones.

[BillyJ]

Oh yeah Mike did you read that post from JC about the green ringer?
He did some cool stuff.
If you can't find it I may have it copied here somewhere....very cool and if your all about GR's these days well worth the read..

[Eb7+9]

... far more the mathematician ....

heh heh, thanx ... a Loveless form of Speculation is all that Math is ... often mis-interpreted as a basis for truth ... :oops:

To my knowledge there are "IN THEORY" three basic ways of achieving so called octave-up effects through waveform manipulation: by (i) dual rectification, (ii) differential starving or (iii) through balanced multiplication ... nptoce that true octaving of a non-sinusoidal guitar signal waveform through analog means is impossible, so we speak in hypothetical sinusoidal test terms "as if" ...

Only the third method will give you true octaving of a single tone, the other two will produce a mix of higher harmonics in which the 2nd is predominant - unlike a fuzz where odd hamonics tend to be present ... often there's a dynamic range assumption that goes along with these circuit: play too hard and the circuit doesn't work as an octaver anymore, more like a fuzz ... the Green Ringer on the other hand performs a bookmatched reflection of the input signal, a full wave rectification process that maintains the shape of the signal waveform very accurately, and because of the way the gain stages are biased there is little worry of hitting clipping limits using a guitar ...

I luv my Green Ringer - I think what makes it so smooth is the trickle current biasing the diodes to help them turn on during on/off transitons ... cool stuff ...

I just finished uploading a bunch of stuff at my site, there's a page on the Green Ringer with some cloning instructions you may want to check out in this regard ... there's an example of an octaver from each category there:

//www.lynx.net/~jc/pedals.html

... the Nulling idea will only work if effort has been made to match parallel components in the phase/anti-phase feeds - it's not a big deal either, the stock circuit sounds fine even with relatively unmatched parts ...

... a very interesting category (i) octaver ... btw, who was Dan Armstrong ?? I'd like to know more about the people behind these cool designs ...

     ... jcm~

[moosapotamus]

I just finished uploading a bunch of stuff at my site...

Lookin good, jc! Those 360+ 'Lite' pedals look great!

~ Charlie

[Mark Hammer]

Who was/is Dan Armstrong?

To the best of my knowledge, for many years he was one of those "go-to" guys in a music store in NYC.  Before the days of people who thought they'd get rich off a fuzzbox, Dan worked at his bench, did repairs for the stars and marketed designs to other companies, Musitronics and Ampeg among them.  Old columns by Jeff "Skunk" Baxter in Guitar Player mentioned him as a mentor fondly.

Along with his quickie-but elegant effects designs that came in just about the worst packaging ever conceived (extruded aluminum cubes that plugged into your guitar jack, and could be stacked to resemble a huge telephoto lens coming off your guitar), Dan also devised the plexiglass guitar body with sliding pickup (Keith Richards used them then, and Dave Grohl has been using one recently; both aged prematurely from the wear and tear on their backs).  I'm sure there are other things he dreamt up that I have quite forgotten about.  Not quite the innovator that Les Paul was, but not all that far behind either.

I believe Kent Armstrong, a noted pickup-maker in England, is his son, though I may be wrong there.

[Mike Nichting]

JCM,
can you explain more about matching parts??  Exactly which ones do I need to match??  I'm not very smart about this stuff so if you could "dumb it down" for me I would much appreciate it~!!  :wink:

Mike N.

[Eb7+9]

Who was/is Dan Armstrong?

thanx Mark, I knew I could count on your encyclopedic knowledge ... sorry for my bad grammar - I hope Dan is alive and well ...

[Eb7+9]

JCM,
can you explain more about matching parts??  Exactly which ones do I need to match??  I'm not very smart about this stuff so if you could "dumb it down" for me I would much appreciate it~!!  :wink:

Alrighty, a bit of background first ... Tweaking came from an early understanding that manufacturing tube audio gear using randomly selected parts (with up to 20% tolerance sometimes) left certain parts of the circuitry performing below theoretical projections ... being easy to remedy at home the art of tweaking was born, differential circuits being most commonly targetted ... the matching of phase driver triode transconductance, the use of matched power tubes or the matching of passives in differential circuits are all directed forms of tweaking - working in concert to achieve a common goal ...

There's lots of places in analog effects where this principle can be applied ... I've seen it used in category (i), (ii) and (iii) octaver circuits, the Univibe and in the Japanese made Shin-Ei, JAX, Royal, and Ibanez octa-fuzzes (posted at UZZFAY) ...

---

In the Green Ringer there's two signal feeds used to produced a rectified waveform - so in this sense there's parallelism going on as part of the process and respecting it should produce a balanced waveform cycle to cycle - obviously what the circuit seems to attempt to do else there would be intentionally unmatched component values in the schematic ...

If the half-cycle envelopes don't match up in height AND shape then it's obvious Fourier-wise that you don't end up with a double-frequency waveform free of fundamental (that's under an assumption of steady-state conditions - n'est-ce pas ?!) ... Now, have a look at the Green Ringer rectifier/mixer circuit below ...



//www.lynx.net/~jc/pedalsGreenRinger.html

You want to match R5, R6 = 10k together,  C2, C3 = 0.047uF together, R7, R8 = 68k together and D1, D2 together in order to produce a balanced waveform (R9, R10 = 22k NOT necessary) ...

If you are working with 1% resistors this means that two resistors are at most 2% apart in value when picking them out of the bag blindly (or is it 1/2% absolute and 1% relative ?) ... anyway, take a few resistors from a lot and find two that are almost identical when reading their value with a multimeter ... ie.  say you've got a bunch of 10k resistors that read like this : 10.12k, 9.87k, 9.98k, 10.09, 10.21 ... then keep the resistors which measure closest to each other, ie. the 10.12k and 10.09k ones ...

Do the same with the Caps - choose values that are close to 0.047uF but pick two which are close to bang on with each other ... Do the same with the 68k resistors ...

Now the Diodes can be tricky - if you've bought recently made diodes (not from the 60's or anything) then they probably have pretty good matching ... besides diodes specs are geometry dependent - so you should expect minute variations in Iso current ... in this circuit, you can stick two same-make Ge diodes of your choice (1n34a or 1n60 ok) and measure their in-circuit voltage drop at idle ... mine read something like 17mV and 25mV, but this can be misleading (I'm not sure) - when these diodes are fully on they should rob the waveform of around 200mV of signal amplitude - this is another place where a waveform producing mechanism should be matched in contribution ... to do this exactly you would need a signal generator and two scope probes to measure turn-on voltages on the diodes during respective half-cycles to get a complete and exact answer ... I'd stick with planting any two diodes from a bag of reputable devices - or if you've got lots of time on your hands you could alligator clip some devices in there after everything else has been matched in the circuit ... somehow, I would expect the differences to be inaudible ...

In matching the 10k, 68k and 0.047uF passives alone you should be able to have the feeds balanced so you can trim out fundamental residuals by using a 22k pot in series with the emitter feed to finally match the Driving Point Impedances in the heterodyne circuit as discussed in my previous posts ...

Note that wavecycle-matching is not completely achievable with this circuit because of the slight difference between the collector node voltage-transfer curvature and that of the emitter node in the heterodyne circuit  ... this transfer curvature difference will likely set the limit to how much residual fundamental will be present once the DPI is matched side to side ...

Happy tweaking !

... jcm~