Transistor Obsidian Perfected(close anyway)

RDV · October 03, 2003, 12:27:11 AM

I've found a couple of changes to the circuit which make it behave much better. Thanks to WGThickPresence for the idea to change the first 10uF to 2.2uF. I then changed the tone cap from .003uF to .22uF which put the treble into a more useable range(less fizzzz). No more oscillation either.

I took it to rehearsal 2-night and it rocked like crazy. This is the one.

Regards

RDV

Marcos - Munky · October 03, 2003, 11:17:28 AM

Hey Ricky, is great to know that now you got the "real thing" of the Obsidian. I will always say: this is the coolest distortion that I heard, and is very simple to build. If anyone wants a good distortion, try the Obsidian.

WGTP · October 03, 2003, 11:25:31 AM

Before Joe "disappeared" there was discussion about the Obsidian and Black Fire and Joe indicated a preference for the BF. That is the one I built and it's great. I think it is similiar to the Obsidian, but Joe decribed the Obsidian as more self dampened and better for power chords. I can't recall what he favored about the BF, but those discussions are where the idea (don't remember who) of using the smaller cap in the first stage came from. Might check the archives, I'm not sure if those discussions are there or not. The BF is even simpler than the Obsidian. Great stuff.

Samuel · October 03, 2003, 12:29:01 PM

Would it be kosher for me to repost the BlackFire schem here? I seem to remember a discussion a while back where people were down on that...

petemoore · October 04, 2003, 01:46:06 PM

You sent me one.
Joe helped me get the first Blackfire going some time ago, before I told everybody I was using hanging garden ckts and complaining about perfboard being 4 times as complicated...now I'm using perf for everything.
The old BF kinda died and got scavenged...As I remem I was quite pleased with it though, now I miss it.
Someone please send me the schematic so I can recall the fond memories of this exemplary ckt!!!! The one I had is glued to the breadboard I used to strap the 'sinewey' ckt to and is illegible now...dohh
If I can get it again I'll use it, not abuse it, and won't lose it!!!

rx5 · October 05, 2003, 06:55:13 AM

RDV,

could you possibly share a diagram of your Obsidian.... I love the sound and wish to build one....

Got the link in runoffgroove but links to a wrong page???!!

Thanks....

my e-add: beamrx5@yahoo.com

-Ralph

Marcos - Munky · October 05, 2003, 10:21:54 AM

You will find the Ally's layout in my site. Hey pete, what's your e-mail address?

Samuel · October 05, 2003, 10:36:49 AM

Here's the last version of the BlackFire, which has a fifth transistor to squelch that nasty oscillation the earlier versions got.

Samuel · October 05, 2003, 10:37:22 AM

Ooops meant to make that a link not an image. Ah well.

rx5 · October 05, 2003, 11:00:27 AM

guys,

I very badly need a circuit diagram of OBSIDIAN.....

veeeerrrrry obsessed by the sound......

thanks...

-Ralph

Alex C · October 05, 2003, 07:24:56 PM

Hey RDV, glad to hear you got something you like out of it. After spending several days tweaking mine and trying some of your suggestions and WGTP's ideas, I think I've got what I want now. I thought that changing the first 10uf to a 2.2uf made it way too "bassy" for my tastes. I do like the tone cap change though- good choice! Thanks for your ideas, and thanks to everyone for their help and suggestions. This pedal rocks!

Alex

P.S. I just learned how to play Van Halen's "Hot for Teacher," and it sounds great throught this pedal, especially the intro tapping. Sweet!

RDV · October 05, 2003, 08:04:59 PM

I considered a 4.7uF instead.

Regards

RDV

Marcos - Munky · October 05, 2003, 09:44:23 PM

Hey Ralph, check my site, there's a layout drawed by Ally.

rx5 · October 06, 2003, 01:11:58 AM

Marcus,

yup got a copy of the layout

RDV,

thanks for the diagram.....

BUT I got a slight problem...cant seem to find 2n5089...

any close substitution for this tranny???

whats the HFE of 2N5089??

Regards

-Ralph

RDV · October 06, 2003, 06:04:38 AM

Quotewhats the HFE of 2N5089??

around 800

hth

RDV

rx5 · October 06, 2003, 10:32:33 AM

thanks man..

so thats why it sounds so "distorty"... the tranny was a high gain....

any infos for close relative of that tranny??

-ralph

RDV · October 06, 2003, 10:47:50 AM

http://www.nteinc.com/search.html
I don't know what you have available in the Phillipines, but if you can get NTE parts you can use this page to find an equivalent.

http://www.smallbearelec.com/
Small Bear also ships world-wide and has what you need.

Regards

RDV

WGTP · October 06, 2003, 10:53:04 AM

Small Bear has the 2N5089's. I've measured the Hfe from 600 to 800. I've also used a variety of other hi-gain low noise transistors, but they may not bias and work right.

Some folks were using MPSA(?)018's. Might try 2n5088's they have almost as much gain and you might find some in the Radio Shack 15 pack, take your magnifying glass.

Samuel · October 06, 2003, 11:00:47 AM

mouser.com and Steve Daniels at Small Bear both carry 2n5089s, and if you live near a place that stocks NTE components, their substitution is the NTE47 transistor. Don't know if there are significant sonic differences from the 47s though....

rx5 · October 06, 2003, 07:09:56 PM

guys,

I plan on building the MOSFET version... what is the "on" resistance of 2N7000 N MOSFET??

currently have IRF540 (3 ohms??) and IRFZ40 (.47 ohms).... I dunno if they could be used in place of 2N7000..... provided I bias the DRAIN leg to 4.5V ??

thank for any info....

Regards

-Ralph

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Transistor Obsidian Perfected(close anyway)