GGG Maestro Sample/Hold Envelope Filter Pedal. Build report. W/Picture...

[theundeadelvis]

Just built this pedal with GGG's layout. The only mod I used was to allow the use of a 1 meg pot for the S/H  speed. This pedal is AWESOME! I used MFP102's for the fets and it sounds pretty good. My only problem is it's a bit muddy sounding. I lose quite a bit of treble and the arpeggiation is quieter than the actual notes played on the guitar. Is this normal? Good build I highly recommend this one!

[troubledtom]

don't know brother,
       i have not built it yet, i bought the board and have to populate it. sorry..............
            peace,
                  - tom

[theundeadelvis]

Its cool Tom, you should definitely solder it up. It's a very specialized pedal but it's so unique it's awesome. I don't think the guys at Xotic had to change a whole lto when they made thier Robotalk. Thanks!

[343 Salty Beans]

You know this already...

but if you're losing treble, can't you just lower the values of the input and output caps to keep some of the highs and cut some of the lows?

[vacuumdust]

the noise transistor is the key...and it's been an endless search.  The 2n3904 it calls for is a bit subtle and muddy like you say, but not bad.  A PN2222A is just awesome but it latches up on a given frequency and then starts to stairstep...kind of cool but also annoying.  If anyone knows how to retain the frequency range of the pn2222a without the latching i'd love to hear it.  Awesome pedal.

[soggybag]

Choosing a good noise transistor and then adjusting the two trim pots to get the most out sample and hold.

[theundeadelvis]

So I put in a NTE47 for the noise tranny and Changed the input cap to .022 and the output to a .047 and it really cleared things up. This pedal is AWESOME!

[theundeadelvis]

Here it is. The finish isn't perfect because I was in a hurry to get this baby boxed up. I love this pedal!

[theundeadelvis]

My favorite thing about this pedal is I got to use one of my pink leds from futurelec! Are the mods (Tonda's) worth doing? Anyone have experience with them?

[Doug_H]

I LOVE IT!!!   Cool finish.

Doug

[Mark Hammer]

Charming finish!  Now all you need is some sort of matching distortion unit with a picture of Don King and you can call it the "King of Hair"!

Are the mods (Tonda's) worth doing? Anyone have experience with them?

I don't have experience with them directly, but can recommend most of them, for the following reasons: they change the feel of the filter effect so that it matches different songs better.

• Certainly the resonance mod is useful.  Sharp resonance always makes S&H changes more "jarring" and effective.
• The attack mod is useful up to a point.  My experience is that with this type of rectifier, turning up the series resistance of the attack control can drastically reduce apparent sensitivity.  There is certainly a small window of attack times obtainable without reducing sensitivity too much, but they are limited.  In contrast, the decay function can be varied over a much wider range without buggering things up too much.  Happily, it also has an impact on the "feel" of the filter sweeps.  The 10k-1M range shown seems quite pleasingly wide, though you may find that 22k  and a 500k pot may be enough for you.
• Tonda has essentially grafted a Mutron rectifier circuit onto the FSH1, which permits upward and downward sweep.  Note that this only affects the envelope-controlled side of things, and not the S&H side.  So, depending on your preferred use of the pedal, that may be of less use... or not.
• The component value change for the sampling clock seems prudent and practical, although there is nothing wrong with using a 1M pot in series with a 470k resistor you can shunt with a toggle to provide fast/slow ranges.
• I think C7 might be worth playing with as a way of introducing some lag or slewing into the clocked filter changes, producing a more "scalloped" rather than "stairstep" change in filter frequency.  Try .47 and see how that sounds to your ears.
• Note that you can change some of the feel of the S&H section by shaping the bandwidth of the noise source.  The trimmer R27 allows you to shape the range of possible random values might be sampled and stored in C9, but you can further shape what those values might be and  how different each successive one might be by lowpass filtering the noise source.  This can easily be done by simply strapping a cap in parallel with R25.  For instance, a 1nf cap would yield a rolloff around 160hz, and a 2n2 cap would drop that down to 72hz,  This would make successive samples more likely to be similar to the previous and next.  In some applications that could be useful.  Defeating it is simply a matter of lifting one end of the cap.  A "more/less random" switch could be easily implemented.

[theundeadelvis]

As always, thank you Mark!

[newperson]

hi,
can you post a pic of the inside?
thank you,
paul.

[alex frias]

I did the mods suggested by Mr Hammer and I've found the step/nonstep the best. But I found that using a bigger value for the cap worked better. I put a SPDT to have a 33uF cap in paralel with the original .05uF C7 cap. I think other values around it works well.
I personaly didn't like the mod with the cap in the feedback chain on the OpAmp.
I've found a BC307 the best tranny for the noise job. I´ve tested a lot of 2N3904, 2N2222 and some BC338...
The unit is prety ticking noise at the extreme setings but the sound is out of this world! And, as a side effect, if you set the resonance at full on using some distortion unit after it you can get a good electro-noise-rythm-machine, even without touching the strings of your instrument.
Someone knows a way to even set this resonance higher to the point of filter selfoscilation or aplied the S&H voltage to control some pitch modulation in a flanger/chorus/phaser?

[chemosis]

is there anyway to vary the frequency of the envelope filter side. i think mark said C3 and C5. how would i wire a switch in there to vary the over all frequencey range to get a little bit lower lowpass. i know that the attack and decay are thee to shift the center freq,  but i was wondering if i could change the overall freq via c3 and c5???