Tonepad Fraverb

[Mark Hammer]

This is a basic FV-1 project: http://www.tonepad.com/getFileInfo.asp?id=122

Finally got mine working.  The project is 12 years old but since I only ordered my FV-1 chip about 3 years ago, I wasn't nearly as tardy with this as I was with the Hyperflange.  I built it into one of the 2-1/2" x 4" modules I have for my modular system, and Francisco's board layout fit the space nicely.  I did not have a 3.3V regulator on hand, so I used one of the many LM78L05 units I had on hand, and ran a 3.3V zener from the regulator output to ground to drop the voltage.  Three toggles and three pots, and two in and out jacks.  It's been almost 45 years since I had to toggle in settings in binary, but with only 8 possibilities not that hard.

The sounds are decent, although not tons of flexibility with the built-in stock algorithms.  Also, note that this does not have mixing capabilities.  So any gentler reverb settings would have to be done external to this module.  If you build yourself one, you may want to build a splitter/mixer into the enclosure to be able to dial in subtler reverb in the background.

It's a stereo circuit with two ins and two outs.  The togglers and pots control both channels at once.  Much like many stereo pedals on the market, plugging into one input seems to yield something out of both outputs.  Haven't yet checked to see if the two outputs are different in any way.  I use a DPDT toggle switch for bypass of one channel.  The other channel is always live.

One thing I did feel compelled to do, like I tend to do with all stereo pedals, is attempt reprocessing.  That is, using the output of one channel as the input signal for the second channel.  I can confirm that some of the programs yield interesting reprocessing outcomes, with extended cavernous reverb, although some yield instant screeching oscillation, so be careful if you try it, or at least employ some sort of padding between channels.  Since the "bypass' toggle only cancels one channel, when I patch things for reprocessing, I can do instant comparisons of once-through vs twice-through, by enabling or disabling one of the channels.

Many thanks for the project Francisco.  Basic, but nicely done.  I'm happy.

[Mark Hammer]

Another interesting discovery.  The stock built-in programs provide 2 pitch-shift programs that can vary the pitch by +/- 4 semitones.  HOWEVER, if one reprocesses that patch/program-selection, re-shifting the already-shifted pitch , one can raise and lower the pitch even more, including a perfect fifth above or below.

Nice, and far more usable. 

The flanger+reverb program, when reprocessed, becomes far more resonant, while the chorus+reverb program becomes more "boing-ey", and the tremolo+reverb program becomes more choppy, almost - but not quite - like the difference between triangle and squarewave modulation.

So, if you make one, make it dual ins and outs with some switchable capability for cascading the two channels.

[iainpunk]

i'd almost considder buildng one with the pitch shift up hardwired and feeding back, so it 'spirals' up. (stacking major 3rd's is cool, i do this with my Pitchfork and cheap reverb pedal on one of my old band's songs for the ''solo'' i do [its more of an soundscape/noise intermezzo, and the singer tells the crowd to take this time to go piss or have a beer, while the rest of the band also takes 5 minutes to get a drink])

is the pitch controllable or is it fixed?

cheers, Iain

[Mark Hammer]

The pitch shift with cascaded channels is simply additive. No spiralling, unfortunately, just 8 semitones up and 8 semitones down (i.e., not a full octave).  It is adjustable on a continuous basis.  So you can raise or lower it as many cents as you want, within the maximum and minimum, rather than stepwise/interval-wise as many pitch-shift devices do.  So if you're playing along with someone else who is a little more sharp or flat than yourself, you can "retune" to match them exactly.

Below is the switch and pot correspondence for effects, which Tonepad does not provide.  This one took me a little while to figure out because the Tonepad layout has the Left and Right inputs on the board reversed.  What was confusing is that the programs that include reverb will yield a signal at both outputs, regardless of which channel you plug into, whereas the pitch-shift programs only yield an output for the specific channel you're plugged into.  With the channel inputs flipped around, I was getting the reverb I expected when dicking around with the toggles, but getting nothing for the Test and two pitch-shift programs.  When I cascaded the two channels with a patch cable, and bypassed one of them I was getting pitch shift.  Once I eventually realized the two inputs were confused with each other, and reconnected them to the appropriate input jacks, everything worked as nature and Spin-Semi intended.

The Low frequency and High frequency controls for the reverb 1 and 2 are not especially obvious but they do manage to trim back the corresponding range of content in an audible way.  When the HF is turned up and the LF turned down, cascading the two channels gets you something that begins to approach shimmer.  Not really shimmer, but moving more in that direction.

I have to tip my hat to the FV-1 jockeys over on the digital & dsp subforum here.  There is some serious magic to be wrung out of these chips, and those who can achieve it are serious magicians.  One of these days, I plan to catch up to the 21st century!

                         S1 S2 S3     P2                       P1                    P0
0 Chorus-reverb     dn-dn-dn   Reverb mix     Chorus rate        Chorus mix
1 Flange-reverb     up-dn-dn   Reverb mix     Flange rate         Flange mix
2 Tremolo-reverb   dn-up-dn   Reverb mix     Tremolo rate      Tremolo mix
3 Pitch shift          dn-dn-up   Pitch +/-4 semitones - -
4 Pitch-echo         up-up-dn   Pitch shift       Echo delay       Echo mix
5 Test - - -
6 Reverb 1            up-up-up   Reverb time     HF filter            LF filter
7 Reverb 2            dn-up-up   Reverb time     HF filter             LF filter

[Ice-9]

pitch can spiral in the FV-1 if you program it that way. I am presuming by spiral you mean like a barber pole spiral ?

[iainpunk]

yes, using pitch shift in the feedback loop of a reverb, gives a kind of Sheppard-tone quality, like a barber pole.

Mark, i meant applying feedback with the pitch shift, not just cascading! the same process a shimmer reverb does with octaves, but with Major 3rd's. it gives a weird magic sound.

cheers, Iain

[Mark Hammer]

Yup, familiar with that ever since Anderton described it in his review of the A/DA Harmonizer pedal, back in '79.  Once I get everything set up so that I can introduce feedback, I'll have to give that a whirl.

[denden]

I'm in the middle of bread boarding the FV-1 (but the protoboard I'm using is slowing me down) .

Mark it had not occurred to me to patch in one channel into the other for 're-processing' cool idea! I'm going to have to add facilities to do that.

In one of the previous FV-1 threads it was mentioned that there was no mixing of the wet/dry signals and this would need to be done externally.  In the other posts there were suggestions for a blend control.

Denis.