Dang it......my octave pedal build aint octaving!

[plexi12000]

i tried the "green ringer" octave up pedal from gaussmarkov website.  pretty simple design....so i thought i'd try it.

it "works"....just no octave. lol   seems there is some "gating"?  if i'm using that term correctly.   it's kinda like "choppy".  like the signal is having difficulty try to get through.  lol-- best i can describe it.   

uses two 5088's and a PNP 3906.   i'm thinking i prolly should have used trim pots to dial in the transistors?  dunno what else it could be.

thanks for any suggestions!

[dbp512]

Haha funny, the same thing is happening with me JCM full wave, which is based on it. There must be something in the octave fuzz water. I haven't gotten around to taking a look at it yet, since i have a handful of more fun circuits that need my attention. I'm mostly positing so I can keep an eye on this thread.

[antonis]

For an "ideal" octave effect, Q2's Rc & Re, Cc & Ce, D1 & D2 and voltage dividing resistors values should be INDENTICAL...

If you don't have a completely full rectified signal with no phase shift (either on -former- positive or negative waveform) which passes exactly halfway Vcc, you can't obtain a clear octave effect..

(imagine circuitry after Q2 as a full wave rectified signal from a center tapped transformer..)

[Mark Hammer]

1) Keep in mind that analog octave-up circuits tend not to display much audible octaving below the 7th fret, and sometimes even higher, no matter how "good" they are.  It's the nature of the beast. I think the only one I haven't built is the Fender Blender, but all the others behave the same way.  A lot of it relates to how strong the fundamental is, relative to the harmonics.  Keep in mind that the higher up you go on the fretboard, the less compliant the strings are, such that harmonic content is drastically reduced.  That's also why most users will recommend using your neck pickup and rolling off the treble.  It all boils down to making the fundamental stick waaaayyyyy out so that when it gets doubled the octave is not hidden in a forest of other doubled stuff.

2) Nothing actually gets "doubled".  It gets "folded over", yes, but that only translates into perceived doubling if the rectified folded-over portions are equal in amplitude.  So the recommendation to arrive at equal portions of the two rectified signals is a solid one.  It's good for the two diodes to have the same forward voltage.  It's also good for the 68k resistors to provide equivalent biasing.

The pair of 10k resistors on the emitter and collector of the 2N3906 are supposed to be identical values to provide "phase-splitting" with equal-but-inverted outputs from the emitter and collector.  However, as I keep repeating (with insufficient documentation and inaccurate recall), nearly 40 years back, in an old issue of Electronotes, Bernie Hutchins mentions that one of those two resistors should ideally be juuuuussst a bit smaller in value than the other for an optimal phase-split.  I wish I could remember which one.  Perhaps one of you more technically apt folks could stick a 9k1 and 2k trimpot in series on one of the sides (emitter OR collector), run it into a scope and tell us more about what gets equal-amplitude outputs.

[Kipper4]

I've got the Lyman green ringer on the breadboard. I'll do some testing tonight Mark and let you know
Thanks for the info

[LightSoundGeometry]

like the others mentioned, you have to analyze the components and get them matching values. then the caveats apply of neck pup, sweet spot on neck etc ..they are a one trick pony type of effect but very effective is used right

no one uses an octave better than SRV and he demonstrates it perfectly in this clip ..out of the 30 minutes, he kicks on the octave for maybe 5 minutes.

according to Analogmans guide to vintage effects, SRV used Roger mayers spaceship looking octave which I have never owned but from demos they sound cleaner like a green ringer..i believe SRV is pushing it with his myriad of classic amps for the drive.

I think you can first hear him kick it on around the 6:44 mark directly after Reese's  Keyboard Solo

[Kipper4]

"Perhaps one of you more technically apt folks could stick a 9k1 and 2k trimpot in series on one of the sides (emitter OR collector), run it into a scope and tell us more about what gets equal-amplitude outputs."

Perhaps not me then.
I just spent 2hrs plus
Injected a sine and sqaure wave into a concertina splitter
>470nf>1k>base
measures both trimmers on E and C for 10k.06
100nf cap on both outputs (E & C)
stuck one of the probes after both output caps
and blow me both signals are completely in phase.
I didnt get as far as amplitude.
Turns out im a numpty who cant even make a splitter. Pissed off now


Now would the real
"technically apt folks" care to have a go or tell me why this is please?

I might as well go look at the amplitudes since it'll be bedtime in about an hour.

edit

heres the test rig

[Ben Lyman]

I might be wrong but iirc, there won't be an octave effect if the 2n3906 is in the wrong way. it's an easy mistake to make because it MUST be "upside down" if you will. check that part out

[Cozybuilder]

Rich try 10K for R5, and a diode after each 100nF cap, both oriented the same. You will be getting a rectified half of the signal on one side (E), and the other rectified half is inverted on the other side (C)- so both halves of the signal are now on the same side of AC ground. These two half waves are combined at the mixer resistor (R6), at double the frequency to give the octave up output. At the cap diode junction, stick in a resistor to ground- the higher the value, the brighter the output, low values (10K - 22K) will give a more "organic" sound. If you're still not getting octave up, try larger caps.

The transistor doesn't really matter, it can be Ge or Si, NPN or PNP. Just set up the bias so that you are getting about unity gain on both the collector and emitter.

[PRR]

> heres the test rig

Well, if that drawing is truly what you built, that's no good. Both outputs are *shorted together*. Of course they are the same.

Two caps, two external load resistors, two separate outputs.

You also need to BIAS that transistor. As-shown, it idles dead cold.

2Meg or 5Meg B to C should put you in a ballpark.

[Kipper4]

Well I've spent a fair whack of time trying to prove/disprove this Mark and the difference in amplitude as far as i can see is negligable. (oscope)
Even with the DMM on AcV. you could maybe tweek the E resistor a few K to match the signals but its hardly worth the effort for most applications (octavers,magnavibes) I wouldnt have thought.
Just my 2 pence.
Thanks for the help Russ and Paul. some of it i had already figured.
It was more about Marks comment than wanting to build a ringer as I realised once I put the gus markov ringer on the board It has a limited use and appeal. Especially with the pick up /fret position thing.
I have a couple of more experiments to do with the octaver but I dont think it will hold a place on my pedal board.
Cheers guys.

[Mark Hammer]

Thanks for that effort, Rich.

I doubt that the nitpicky aspects of the resistance values would make a world of difference.  Rather, there are so many other ways in which the two complementary signals required for audible doubling could conceivably be out of balance, that I figured it was theoretically possible to address all of those other sources of imbalance and still not get optimal doubling because the emitter/collector resistances were screwing things up; i.e., just one more detail to be mindful of.  In any event, it is improbable that analog octave-up fuzzes historically used 1% resistors for the phase-splitter.

The Green Ringer, by itself, is nothing spectacular.  Mine has a Stratoblaster FET booster built in as a front end. and a complementary attenuator pot on the final output.  I find that nets me a more usable tone.  The original Armstrong circuits were, after all, "minimalist" circuits that aimed for achieving a category of sonic outcome with the fewest possible parts.  So it shouldn't surprise us that the GR needs a bit of "help".

[Kipper4]

I guess that's why Mr Lyman put a fuzz up front too.
Your more than welcome Mark.
Plus I learned some lessons.

[Ben Lyman]

I just built 2 more of my "FORM-INATORS" and as an experiment I used two different Ge diodes from the 2N3906 emitters (Note that the emitter is connected to +9v via 10k, not ground) a 1n270 and a 1n34a.
I also found that the difference in Si diodes (2n3906 collector) made an audible difference, a 1n914 was very subtle while a 1n4148 had a nice and harsh raspy octave effect (I know these diodes are "the same thing" so I don't know why I got a different sound from each but I did)
Ge diode differences: one sounded warm and "old school" classic, the other (w/higher v drop) sounds nice and harsh and raspy, clear octave up.
Remember, I also have a built in "Bazz Fuss/Electra" hybrid up front of this whole thing and a B500k pot to blend my octave diodes: 
http://www.diystompboxes.com/smfforum/index.php?topic=113381.msg1050204#msg1050204
In closing, I suggest trying this experiment:
Put a resistor (anything from 10k to 500k) in series with the diode coming from the PNP Qe (note again where emitter is) and always use a booster stage with the Green Ringer.
And... let me know if any of that works     

[Mark Hammer]

It's also good to incorporate some sort of appropriate lowpass filtering, such that a person could simply hit the stompswitch and get decent octaving, without having to roll the guitar tone back to optimize things, and then roll it back up again when bypassing the octave.  In other words, condition the signal optimally inside the pedal.

[Craiz]

I have a similar enough problem that I figured I'd just jump into this thread instead of making a new one. Green Ringer, really nice distortion sound, definitely no octave sound even under 'optimal' conditions. My multimeter probing tells me that all of the components that need to be equal in value are or are reeeeeally close, so my hunch is that that isn't the problem .

The next move to my knowledge is voltage measurement of the transistors to try and see if they don't match expected values - except I don't know how to do that. Is it connect power to the pedal and measure DC voltage from +9 to each leg of the transistor?

Thanks, and sorry again for the piggyback.

[LightSoundGeometry]

I might be wrong but iirc, there won't be an octave effect if the 2n3906 is in the wrong way. it's an easy mistake to make because it MUST be "upside down" if you will. check that part out

or in a push-pull configuration

https://en.wikipedia.org/wiki/Push%E2%80%93pull_output

somehow the fundamental cancellation of harmonics produces an octave up effect..you do not have to match any parts at all using this method

[duck_arse]

Is it connect power to the pedal and measure DC voltage from +9 to each leg of the transistor?

Thanks, and sorry again for the piggyback.

it is that simple, but we/you want to measure against ground if it is a neg ground circuit. just clip your black lead to the sleeve of a jack, then poke with the red and record results.

[Kipper4]

I might be wrong but iirc, there won't be an octave effect if the 2n3906 is in the wrong way. it's an easy mistake to make because it MUST be "upside down" if you will. check that part out

or in a push-pull configuration

https://en.wikipedia.org/wiki/Push%E2%80%93pull_output

somehow the fundamental cancellation of harmonics produces an octave up effect..you do not have to match any parts at all using this method

Can I ask. Have you tried this LSG?
Do you have a schematic to back it up? Sorry to be pescimistic but I'm intrested to know where this idea comes from and if theres any evidence to support it.
Thanks
Rich

[antonis]

somehow the fundamental cancellation of harmonics produces an octave up effect..

My elementary knowledge is restricted to frequency discrimination between Fundamental and Harmonics (even & odd)..

The term "fundamental cancellation of harmonics" confuses me a little bit..