Obsidian-Vulcan-Blackfire differences?

[Xavier]

OK as I'm boxing my Boogey now and after tweaking my Peppermill it sounds good, I want to build some of Joe Davisson's circuits.

According to the reviews, all of them seem to be very good high gainers, but there's not any thread that explains the sonic differences among them.

As the schematics seem to be similar,has anybody built all three of them? any comparison / similarity with other known pedals?

How do they differ from each other?

[WGTP]

It's hard for me to say, because I've built them on breadboards and don't have them all going at the same time.  They are all very cool.

I would say the Vulcan is the squishyist (most compressed) of the bunch, followed by the Blackfire.  I do have the Blackfire boxed and it has a BIG sound that blends well with a tube amp or sounds good into solid state.  The Vulcan may be better for a lower gain sound.

The Obsidian seems to be associated with Metal, but the Mosfets can do more than that IMHO.  Check out ZVEX new distortion.

There is also a JFet Vulcan.  Once you build them, you may want to tweak on the caps that effect the EQ.

I guess it is sort of a textural/character difference that is difficult to describe.   

[Xavier]

It's hard for me to say, because I've built them on breadboards and don't have them all going at the same time.  They are all very cool.

I would say the Vulcan is the squishyist (most compressed) of the bunch, followed by the Blackfire.  I do have the Blackfire boxed and it has a BIG sound that blends well with a tube amp or sounds good into solid state.  The Vulcan may be better for a lower gain sound.

The Obsidian seems to be associated with Metal, but the Mosfets can do more than that IMHO.  Check out ZVEX new distortion.

There is also a JFet Vulcan.  Once you build them, you may want to tweak on the caps that effect the EQ.

I guess it is sort of a textural/character difference that is difficult to describe.   

Marty Mart also suggested the Vulcan, and I like your comment about the compressed tone. Do you consider it a dist pedal or more like a high gain OD? how are the in between tones?

I think we should have a sticky thread with reviews of all we've built....that would make it easier for the rest of us. Sometimes the sound samples are not very convincing....

Thanks for the hints !!

[RDV]

Transistor Obsidian

I've got a schem on the computer at home. I don't know why Joe abandoned this circuit, it's one of my favorites, I play through mine all the time at home.

RDV

[WGTP]

About the time I was going to try that one, the BF came out, and then the Vulcan and then the BS250 P channel Obsidian, so it sort of got left out.  Nice sample. 

I would say the Vulcan is more HIGH gain overdrivish than the others, but it's a judement call.  May be slighlty less agressive than the other 2.  If you looking for something to contrast with the others you have built, the BF might be the most different since you have been working with Jfets/Mosfets. 

Xavier, seems like you need a breadboard.   

[Xavier]

Xavier, seems like you need a breadboard.   

I have it, I have it.......but I still have to build a jig around it to have some pots / in-out jacks ready to go, and there's always a pedal to be built before that

[WGTP]

I just have a 100K output pot and jack soldered together with 2 leads to the board and and input jack with 2 leads.  I have 2 different boards and it sits on top my amp. 

I have gone nuts mixing and matching the different Davidson stages, tweaking EQ etc.  It's addictive.   

[markm]

So,
The Vulcan is more of a lower gain circuit?

[WGTP]

No, I wouldn't describe any of them as lower gain, the Vulcan may just be a little smoother, slightly less agressive, IMHO.   It's easy enough to reduce the gain, if they are too hot. 

[markm]

I see.
Thanks for the info, I'd been thinking about the Vulcan but, most of Joe's stuff is too over the top for me. 

[WGTP]

Some folks remove the by-pass caps for lower gain, but then you may need to adjust elsewhere for the increase in bass.   You could also use just 2 stages instead of the 3. 

[markm]

Thanks for the info;
I may give it a shot yet, it is still on my list which is growing by the day!

[Xavier]

I did a couple of gigs with my actual setup which include the BSIAB and the Dr Boogey. The BSIAB has a real good chunky tone but still lacks bass. I tweaked it a little bit but it just can't stand beside my Barber Direct Drive and my H&K Tube Factor. Besides this, my Boogey is giving me much more headaches than I expected. It oscillates like crazy, even without any signal through it. I have done everything. I've used shielded cable, put an AMZ basic buffer, checked the circuit 100 times..... I'm going to rebuild it from scratch.

So....... new projects. Obsidian and Vulcan, as I want to hear them by myself and the comments from everyone are nice. I'll keep you updated.

Also ditching the Peppermill. Too subtle, however if you have one just give it to your bass player. It gives that round, rock sound without being too intrusive. Will build the Highway 89 instead.

Man, you can be tweaking all you want , when it comes to use these DIY pedals at a real gig, sometimes your perception changes BIG TIME........

[zeta55]

Transistor Obsidian

I've got a schem on the computer at home. I don't know why Joe abandoned this circuit, it's one of my favorites, I play through mine all the time at home.

RDV

Like that sound a lot, is the ObsidianT with 2N5089? Nice playing RDV!

/Krister

[Cliff Schecht]

I've built the one that uses 5 5089's and just remember how noisy it was, but it had a great sound. I've also heard that his MOSFET designs have a lot of white noise.

[zeta55]

I've built the one that uses 5 5089's and just remember how noisy it was, but it had a great sound. I've also heard that his MOSFET designs have a lot of white noise.

Would you describe it as to noisy, compared to other high gain distortion units?

/Krister

[Xavier]

I've built the one that uses 5 5089's and just remember how noisy it was, but it had a great sound. I've also heard that his MOSFET designs have a lot of white noise.

5 5089's? I have built mine with only 4 !!. Maybe the extra one you used was the cause for the noise

Now seriously, the analog alchemy schematic has 4 transistors in the T version. Was there a 5 transistor version?

[Marcos - Munky]

Now seriously, the analog alchemy schematic has 4 transistors in the T version. Was there a 5 transistor version?

Not that I remember. I've been collecting different Obsidian schematics, and this is what I got:

2HV: 5 2N7000, runs at +36v
Revision B: 4 2N7000
Revision D: 4 2N7000
Transistor Revision B: 4 2N5089
-T: 4 2N5089, 1st stage is the Blackfire stage
-M: 3 BS250

There's at least 2 schematics for a 5 transistor Blackfire, one seems to be very noisy.

[aron]

I've built them all. I love them all, but the Vulcan was my most favorite, but the most noisy pedal of them all. The Black Fire is killer but the mids are different ( you might love it)

Aron

[RDV]

Transistor Obsidian

I've got a schem on the computer at home. I don't know why Joe abandoned this circuit, it's one of my favorites, I play through mine all the time at home.

RDV

Like that sound a lot, is the ObsidianT with 2N5089? Nice playing RDV!

/Krister

Thanks!
That's the old revision B with some mods that I worked out with Joe.

RDV