Bigfoot FX Magnavibe

Zombie_Crush · Post by **Zombie_Crush** » 04 Sep 2011, 19:45

Hi greenskull

yeah its pretty quiet now, even with a spot of EQ - for some reason the mistake in the pedal was causing another pedal to flutter, at first I thought it was the magnavibe, turn out to be my Boss RE-20.

Hope you have better luck

greenskull · Post by **greenskull** » 05 Sep 2011, 05:07

Thanks Zombie_Crush, will have to tear it apart and see what I can do.
I added an op amp input buffer to mine, maybe that's causing a problem. Sounds really good though!

Zombie_Crush · Post by **Zombie_Crush** » 05 Sep 2011, 12:29

Could well be

Good luck!

Zombie_Crush · Post by **Zombie_Crush** » 05 Sep 2011, 13:35

Nocentelli

any idea how i can get rid of the annoying clicking sound from the DPDT when switching on the new tremolo switching version?

am wondering if i could remedy it by wiring a ground wire to the DPDT's B1/A3 lugs - from either the - Circuit Ground or the Star-Ground on the input jack

would that work?

Nocentelli · Post by **Nocentelli** » 05 Sep 2011, 14:17

Zombie_Crush wrote: am wondering if i could remedy it by wiring a ground wire to the DPDT's B1/A3 lugs - from either the - Circuit Ground or the Star-Ground on the input jack

would that work?

A3 is already grounded (or should be!), and if B1 is grounded it will effectively bypass the 6k8 resistor from Q1's emitter when you switch to vibrato - I'm guessing this will result in a large volume increase.

Hmmmm... I'll have a think about this, maybe someone else can chip. I'm ok with curing switch pop in bypass circuits, not sure the cause of it here.

Zombie_Crush · Post by **Zombie_Crush** » 06 Sep 2011, 11:34

Yeah! i could see A3 is grounded to the board, but was wondering if maybe i need to do the same with B1, or B1 wired to A3

Have posted in debugging - hopefully we will get a response ... great vibe pedal all the same!

thanks again

pinkjimiphoton · Post by **pinkjimiphoton** » 30 Oct 2011, 03:45

hey guys, anyone got any tips for my newb ass to minimize some of the background noise on this? i've noticed on the most recent pedalboard a lot of "hash" in the background when it's on...but no idea where to mess with the circuit...figure a judiciously placed cap or 3 ought to do it, right? but where? thanks in advance!

greenskull · Post by **greenskull** » 31 Oct 2011, 00:14

pinkjimiphoton wrote:hey guys, anyone got any tips for my newb ass to minimize some of the background noise on this? i've noticed on the most recent pedalboard a lot of "hash" in the background when it's on...but no idea where to mess with the circuit...figure a judiciously placed cap or 3 ought to do it, right? but where? thanks in advance!

Maybe not a direct answer, but the noise I was experiencing went away when using with a non-true bypass pedal (Fender Starcaster chorus).

RnFR · Post by **RnFR** » 31 Oct 2011, 03:18

I didn't notice any excess noise when I breadboarded it. maybe a bad transistor? I really like this with a FET buffer in front. much clearer sound.

pinkjimiphoton · Post by **pinkjimiphoton** » 01 Nov 2011, 19:34

it's just kinda hissy and a little rfi happening....maybe i need to add some power supply filtering in the pedal, or tack a small cap on somewhere?
unfortunately, no power for last few days, so can't play with it...may not have ac for a week this time. hoo boy, good times.

sugarinthegourd · Post by **sugarinthegourd** » 31 Jan 2012, 16:37

Was just looking at this schematic and the associated layouts (great job, all!) and I wonder if this electrolytic cap wasn't drawn backwards? It makes more sense to me the other way 'round, and that's how it's oriented on the Wobbletron.

What do you think? Can someone with the original degooped circuit verify? I am hoping to breadboard it this weekend, so I'll see what the volategs are around that cap, and if it sounds different one way or the other.

Thanks

Nocentelli · Post by **Nocentelli** » 31 Jan 2012, 17:06

I have an idea that Kindafuzzy has sold the original Magnavibe - But I may be wrong. It does seem odd that that cap is reversed compared to the Wobbletron, when they are so similar in every other way. However, the Magnavibe definitely works as-is, but I've never managed to get a single wobble out of the Wobbletron...

briggs · Post by **briggs** » 31 Jan 2012, 17:30

All I can say is that the lfo is a phase shift oscillator in it's simplest form (thanks for that earthtones!): http://www.zen22142.zen.co.uk/Circuits/ ... lf_osc.htm

I sidestepped this issue by using non-polarised caps

Nocentelli · Post by **Nocentelli** » 31 Jan 2012, 20:08

Haha - Now that LFO schematic has the caps oriented differently to the Magnavibe AND the Wobbletron.....

KindaFuzzy · Post by **KindaFuzzy** » 31 Jan 2012, 23:33

Good catch sugarinthegourd, you're right, it's oriented the other way on the original, which is long gone but I took good pics, so I could confirm stuff like this. http://www.flickr.com/photos/35422385@N ... 139715275/

sugarinthegourd · Post by **sugarinthegourd** » 01 Feb 2012, 02:27

I wonder if it matters & if these need to be polarized at all...looking at the LFO in the EA tremolo there's a similar circuit using non-electrolytic caps. May just be easiest & cheapest way to get 1uF caps...

mmolteratx · Post by **mmolteratx** » 09 May 2012, 22:30

Board mounted pots/LED layout project attached. Should fit in a 1590B no problem.

danielzink · Post by **danielzink** » 06 Apr 2013, 04:19

Magnavibe in a 1590a

Re-worked Dimebugg's layout a little in DIYLC.

Used one of the 99 cent optocouplers from Electronic Goldmine...spec'd out around 2meg so I tossed it in there. Works great.

rhinson · Post by **rhinson** » 12 Apr 2013, 21:06

just built one of these and it's sounds pretty much like a small old magnatone amp i worked on a few yrs back. i was just wondering how to increase the depth on this circuit. are there any values in the circuit to change or is it pretty much dependent solely on the ldr and led combo? thanks. rh

also any reason to use a mpsa18 or would any other bjt type be fine (2n5088 or 5089, etc).... thanks

pinkjimiphoton · Post by **pinkjimiphoton** » 16 Apr 2013, 01:55

i tried forever to get a wobbletron going. only tim escobedo himself appears to have pulled it off.

any high gain transistor should work... i'd socket and play until it sounds good.

i haven't tried it yet, but i bet a mosfet like vn2222 would probably work in there, too...

Bigfoot FX Magnavibe [traced]