Passive distortion/overdrive

vendettav · July 26, 2011, 03:45:52 AM

ok so for this particular situation I am in search of passive distortion or overdrive. any ideas on this?

frequencycentral · July 26, 2011, 04:03:46 AM

http://www.projectguitar.com/tut/blackice.htm

vendettav · July 26, 2011, 04:55:18 AM

looks neat, can you put it up in a box? not in the guitar. how would you do that?
and what kind of Shottkys do i need, i dont know much about those other than that they're diodes ?

petemoore · July 26, 2011, 07:05:10 AM

What is the pickup output> can it exceed the diode voltage thresholds ?

anchovie · July 26, 2011, 07:22:09 AM

Quote from: vendettav on July 26, 2011, 03:45:52 AM
ok so for this particular situation I am in search of passive distortion or overdrive. any ideas on this?

What's the amp? If it can run dirty but clean up with lower input levels, build a footswitchable volume control to act as an attenuator.

vendettav · July 26, 2011, 09:49:54 AM

well ok here's the back story, i found this thing in one of my stores. it's a speaker which goes really loud, that you connect to your phone or something, charges from USB... and so I was thinking if i could design a passive box to go between it and my guitar to play at nights and all that...

Mark Hammer · July 26, 2011, 09:02:54 PM

1) Anything describable as "overdrive" would necessarily be active since it would have to provide gain...right?

2) The Black Ice is a pair of diodes with a somewhat lower forward voltage (hence clipping threshold) than germaniums. You stick it between the input to your guitar volume pot and ground. They will clip if your signal level exceeds the forward voltage of the diodes. It can, but only under certain conditions, because the forward voltage is not THAT low. You could certainly produce clipping with a 6-string power chord on most pickups. To generate clipping with fewer than 3 strings would likely require a higher output humbucker and use of wound strings. Certainly do not expect to play distorted single notes on your high E and B with single-coil pickups.

Earthscum · July 26, 2011, 09:49:50 PM

I actually have a schottky in my bass with a switch. Mine just goes across the jack. I used a single diode, anode to ground, cathode to the "signal" side, to clip the negative side, and because I read somewhere when doing it that it's recommended that way for single. Dunno, works great for me.

The heavier strings create a lot more energy than the lighter guitar strings. It clips really nicely, harder to clip with my fingers, really grinds when I'm picking. Works great with the Nurse Quacky. I can make it a bit more sensitive, and since the diode clips the half of the signal that NQ uses for detection, it makes the Nurse envelope more of a PWM input, and less sensitive. With the push of a button, it goes from "wah wah" to more of a "wuh wuh". Keeps me from bending over.

Also causes other interactions. Higher impedance inputs (like jfet buffers) make it clip easier, and lower imp obviously sucks more signal, and it won't clip as easy. I've considered making a buffer box that is switchable between 2 or 3 impedances to take advantage of this. On the breadboard, it seems to have some promise to have a nice range of sounds and interactions. The SK117 is happy with ground bias resistors from about 100k to 1M without getting all hissy about it (sorry for the pun). Haven't looked as close at other jfets, but it seemed to give me a good range.

vendettav · July 27, 2011, 02:02:38 AM

hmm ok i remember this company that was making passive boosters. is it possible to put a biooster like that in the line and then only shottkys so the forward voltage is already high?

anchovie · July 27, 2011, 02:29:48 AM

Quote from: vendettav on July 27, 2011, 02:02:38 AM
hmm ok i remember this company that was making passive boosters. is it possible to put a biooster like that in the line and then only shottkys so the forward voltage is already high?

I'm sure it's possible, but you'd need one of those boosters first!

Whether is sounds good or not is a different matter. Can't you just run a distortion that you already like the sound of using a 9V battery?

vendettav · July 27, 2011, 04:10:05 AM

well i guess it'll be my final option, but i was thinking a passive idea could go well

darron · July 27, 2011, 05:09:40 AM

has everyone seen these?

http://www.cavepassivepedals.com.au/

vendettav · July 27, 2011, 05:25:02 AM

Quote from: darron on July 27, 2011, 05:09:40 AM
has everyone seen these?

http://www.cavepassivepedals.com.au/

BINGO i was refering to this

they have a lot of pedals that they claim to have a boosting capability... so whats inside the box??

anchovie · July 27, 2011, 05:39:04 AM

Probably a passive transformer to increase the voltage.

I like how their phaser requires you to wave your foot back and forth over LDRs to create a passive LFO. Must be great to get an aching leg while saving a few mA of current in a pedal running into a heat-spewing tube amp!

vendettav · July 27, 2011, 05:59:54 AM

Quote from: anchovie on July 27, 2011, 05:39:04 AM
Probably a passive transformer to increase the voltage.

I like how their phaser requires you to wave your foot back and forth over LDRs to create a passive LFO. Must be great to get an aching leg while saving a few mA of current in a pedal running into a heat-spewing tube amp!

so passive transformers? then a simple low voltage tranny dist/boost and stuff??
hmmm

well why dya say so. actually a manual phaser could be fun (tho it's me thinking it's fine cause i'd use it for manual phaser, not as a usual phaser... which would be painful)

Gurner · July 27, 2011, 08:01:29 AM

Quote from: anchovie on July 27, 2011, 05:39:04 AM
Probably a passive transformer to increase the voltage.

I like how their phaser requires you to wave your foot back and forth over LDRs to create a passive LFO. Must be great to get an aching leg while saving a few mA of current in a pedal running into a heat-spewing tube amp!

Lol, I'm waiting on their passive leslie emulation ..... sit with your guitar & amp on a kiddie's playground roundabout & get someone to spin you very fast.

anchovie · July 27, 2011, 08:35:18 AM

Passive delay - point the speaker down a well.

vendettav · July 27, 2011, 10:51:53 AM

Passive hall reverb: play in a big hall.
Passive plate reverb: go to a restaurant and ask for some plates

Passive ping pong delay, play unplugged at a ping pong championship
Chorus? go rent a church choir

I can do this all night long

anchovie · July 27, 2011, 11:08:22 AM

Passive harmonizer - tune the pairs on a 12-string guitar to the intervals of your choice.

wavley · July 27, 2011, 11:13:46 AM

Quote from: Gurner on July 27, 2011, 08:01:29 AM
Quote from: anchovie on July 27, 2011, 05:39:04 AM
Probably a passive transformer to increase the voltage.

I like how their phaser requires you to wave your foot back and forth over LDRs to create a passive LFO. Must be great to get an aching leg while saving a few mA of current in a pedal running into a heat-spewing tube amp!

Lol, I'm waiting on their passive leslie emulation ..... sit with your guitar & amp on a kiddie's playground roundabout & get someone to spin you very fast.

I had a friend that one time while jamming in his living room was playing the keyboard through a little smokey amp that he was spinning over his head by the cable, that made a pretty good passive leslie (except for the active part of it being an amp and the active part of physically spinning it)

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Passive distortion/overdrive