Mutron Octave Divider Built... Working?

[loki]

hi guys, i just completed today a clone of the mutron octave divider which i've been after for a long time...
it went pretty smooth, just one slight mistake in powering the wrong lug of one of the opamps, but after i corrected it everything was working good...
the real challenge was actually fitting two circuit boards, one power supply board with two 4700uF caps and all pots, jacks, and switches in a BB size enclosure, but i somehow managed to do it..
now my question, for those who have already built one/have the original...
if i hold a low note for say 2-3 seconds the octave down sound disappears, but this doesnt happen with short notes or for notes up to around 12+ fret... is that meant to be this way? or is it a mistake on my construction?
plus, unlike the other build review i've read (hank reynolds III i guess), on my build the stability switch actually seems to do something.. when it's off the octaves down are delayed from the straight signal...
if you know something about this please let me know
thanks!

[hank reynolds 3rd]

Hi Loki,
The one I built was from a schematic that omitted the 220k resistors near the 4011/4013, so I'm guessing that this has something to do with the stability switch (i'm ebuilding it sometime soon,as its massive!!)

Maybe the FET is what's causing the notes to die out too soon...I used a 2n5457,as mentioned in one of the schematics I had


Sam

[loki]

i used the same FET too... so i don't know...
i also noticed that the octave down is perfectly clean.. while the straight signal comes out slighly boosted.. it distorts a bit.. can it be caused by the opamps? 
also the ringer doesn't seem to work... maybe i ought to check it out when i have time

[zeta55]

I had the same problem with my octave down, though in another circuit.
It uses a 4013 for the octave down. Looking in the scope I noticed that below 140Hz I got an extra peak in the waveform from the OPA to the 4013. It got countet at 280Hz and divided, the octave downthen ended at the original 140Hz.
I solved it with RC filtering before the OPA stage. Now it goes down to 82Hz before the extra peak appears.

/Krister

[loki]

how would you do a RC filter?

[zeta55]

I ended up with a 22K resistor in serie with the signal and a 37nF cap to ground. Haven't played it yet, only scoped. Will try it later tonight.

/Krister

[zeta55]

I ended up with a 22K resistor in serie with the signal and a 37nF cap to ground. Haven't played it yet, only scoped. Will try it later tonight.

/Krister

Well, I've did some abusement with the guitar. Sounded realy nice on the octave down also on the low E  . But, sounds like i loose the octave down above the 12:th band on the B string. Aint that life

/Krister

[loki]

hmm yea those octave down pedals are weird things
i'll see what i can do with mine

[Paul Perry (Frostwave)]

But, sounds like i loose the octave down above the 12:th band on the B string. Aint that life

Yep, that would be dividing down the overtone