Octavia Project Problem?

[tubeboy76]

Ok you techies out there.  I just built my first pedal kit, a GGG TOCT Octavia clone.  I'm pretty tech savvy but unfamiliar with the circuit.  The pedal seems to work fine and sounds great.  My questions are simple:

1) What is the purpose of the audio transformer in the circuit?  Does it divide the signal to create the octave effect?

2) The kit I built has the optional Octave on/off footswitch.  When I click the octave on, the level drops a fairly significant amount (enough to not be able to use it in a gig) and the sound compresses, a lot.  The fuzz on its own is very big and open sounding but when I kick on the octave, it seems to lose mids and level.  The level seems to increase as the note sustains.  Is there some way to switch the octave on and still get a nice open fuzz/octave tone or is this the nature of the circuit.  I am unfamiliar with the Octavia.  Does anyone know of any mods to get rid of this?

Thanks for reading.  I'm doing tons of research on the subject but any input would be wonderful. 

Long live pedals!

[GibsonGM]

1)  A signal passing thru a transformer is inverted - as the primary voltage increases, the secondary is out of phase (collapsing field).  Because the secondary is center-tapped, there are opposite polarities of the signal going on between center and top, and center and bottom, at the same time.  The diodes on the secondary clip the signal in a full-wave configuration, leading to a doubling of frequency just as in a power supply.  The Octavia uses that principle to double the frequency (clipping both halves of the waveform), giving you your octave. Sorry this isn't a good explanation:  Look up full wave rectification for more on how this happens...

2) sounds like a wiring problem? Some sort of capacitance issue offered by the wiring?

[liquids]

2) The kit I built has the optional Octave on/off footswitch.  When I click the octave on, the level drops a fairly significant amount (enough to not be able to use it in a gig) and the sound compresses, a lot.  The fuzz on its own is very big and open sounding but when I kick on the octave, it seems to lose mids and level.  The level seems to increase as the note sustains.  Is there some way to switch the octave on and still get a nice open fuzz/octave tone or is this the nature of the circuit.  I am unfamiliar with the Octavia.  Does anyone know of any mods to get rid of this?

I've got an octavia on the breadboard I'm in the troubleshooting stage with, but thought I might offer help in general....

The octave is simply 'losing' half of it's signal when it octaves.  Read this, it will come in handy:  http://geofex.com/effxfaq/distn101.htm

In short, the GGG version of this octavia uses the same methodology as the Fulltone Ultimate Octave--and the fOXX tone machine that the Ultimate Octave clones--to switch between an octave and non-octave mode.  My understanding is, on the fOXX it was simply a switch - not meant to be done on the fly, just an option.  Fulltone created the 'ultimate octave,'  again based on the fOXX, which turned that switch into a footswitch.  

The non-octave mode in these fuzzes is likewise distinct, due to the half wave rectification fuzz sound (see above link).   However, the stage that generates the half / full wave rectification in those pedals is followed with some other gain stages, which compress the sound and dirty it, so that the 'level' between the octave and non-octave is closer, at least close enough for most ears.  The foot switch concept (like your pedal) is somewhat of a usable novelty on the pedalboard, a little something extra....a nice touch, if you will.  

The tycho octave is what fulltone cloned and calls the 'octafuzz,' not unlike what you are building schematic-wise.  At some point---depending on how much you believe his ad copy--a Fulltone employee mis-wired an octafuzz and it didn't octave--probably left out or didn't solder one of the diodes, so it just fuzzed, going from full wave rectification to half wave rectification. Allegedly it was a mistake, 'but Fuller liked the fuzz.'  Whatever the truth may be, at some point fulltone added a toggle switch, which probably just makes/breaks the connection with the diode so that sound was available, which was not always available on it's Octafuzz model...

GGG has now gone so far as to take the concept and make the switch a stomp switch - like the Ultimate Octave did as compared to the fOXX.  However, the octavia/TOCT it's not followed by any gain stages, so the tone is not as compressed.  Likewise, since it is rectifying the 'fundamental' of the note being played, half the signal is being squared off....and likewise, the sound is nastier, and brighter due to apparent frequency, etc.  Note that the octave fuzz is the 'original' sound in this pedal, and the regular fuzz is the add on.

So while it's an interesting option, it may not be usable live, more so just novelty.  However, try playing along to some records and see how well it cuts in a mix--it might surprise you.  Likewise, experiment with running it before or after a gentle overdrive...the compression may help the levels be more even, as the case may be.  Lastly, you could probably rig up a 3PDT which not only makes/breaks the connection to one of the diodes like yours does now, but also sends the siganl to a different volume control, if you were so inclined.  Now you would be able to have one level for the fuzz, and another volume control for when you switched on the octave, maybe at the cost of the LED...I'm sure it's all possible if you think it through.

Back to the breadboard to hear it firsthand....maybe.    Enjoy!

[ReginaldBisquet]

Same kit but different question.  Actually, a fairly stupid one at that: I forgot to solder the two side posts of the audio transformer.  The top 3 and bottom 3 are soldered but not the two big fat ones on the sides.  The pedal works at this point, but notes seem to have an interesting decay.

Should I go back and solder the two side lugs of the audio transformer... or is it not necessary?

Gratuitous pedal shot: