Tone Control on the Blackfire

[Paul Marossy]

So, if I put a Marshall-style tone stack on this circuit, where would be the best place to place it? I was thinking between the junction of the (2) 470K resistors at the output and the 100K volume pot.

Or should it be done differently? I'm kinda comparing this to the Smash Drive I have with this the Marshall tone stack scheme.

[Gary]

I'd stick the tone stack between on the output of the last transistor.  You can eliminate the output cap that way.  You may need to play with the 470k voltage divider, or possibly eliminate it all together.  You'll lose some volume when you add the tone stack.

This is the way I'd try it.  As always, breadboard first!

Best regards.

[Gary]

English is bad today.  I meant put the tone stack on the output of the last transistor stage and eliminate the output cap and possibly the voltage divider.  Go from the wiper of the treble control to the output jack, no cap needed between.

Sorry about that.

[Joe Davisson]

I have one made like that. The 470k limiting resistors were yanked and replaced with the tone controls, using Marshall-type values. Worked real good!

-Joe

[brett]

It surprises me that you want to add an extra very nonlinear tone section in your pedal to the one that's in your amp. To me, adding a big muff pi tone section or other high-pass/lo-pass tone controls always seems the way to go (ie when "flat" it doesn't mess with the overall bass/mid/hi balance like the Marshall section will).  

Having said that, at least the classic Marshall sections have lower losses and are not as seriously top-end boosting as the Fender tone sections.  One of those sounds fine, but I reckon that two of those would really make a mess.

[idlefaction]

try the vox stack, i personally like it more than the marshall one  

[Paul Marossy]

Gary,

Losing little bit of volume doesn't bother me. I usually have the gain near max. and the volume set at about the same level as my un-effected guitar signal, or maybe just a slight boost.


Joe,

I was also thinking the Marshall tone stack would sound good with this circuit. You have a pretty good ear for tone, so I trust your judgement on that.


Brett,

I hear what you're saying, but I really don't do much EQ'ing with my amp. I rely on the tone controls on my pedals more. I normally use a simple one knob tone control circuit on my pedals, but sometimes a three band tone control suits my needs, too.


idlefaction,

I am familiar with the Fender and Marshall topologies, but not Vox. What does a Vox tone stack look like?

[Ansil]

idlefaction,

I am familiar with the Fender and Marshall topologies, but not Vox. What does a Vox tone stack look like?

dude you have to download duncans amp calculator and play with the vox.. you will not be sorry.  with two knobs i got everything from top end boost.  mid scoop, to mid boost with slight highs and to full on rockin  meaty bottom.

[Doug H]

I never considered trying the Vox tone stack with the Blackfire. The Vox can do a wicked mid scoop so I bet it would sound good.

When I did my BF, I dumped the 470k/470k divider and just stuck the Marshall tone stack in its place (like Joe did). I added a 220pf from output to ground just to roll off the highs a little. It's not harsh, just really *clear*, one of the great things about the BF. Maybe a little too clear for high gain (?) so I put in that cap.

FWIW, I tried a JFET simulation of a Soldano once and it sounded just like the Blackfire. The Blackfire sounds really great, my favorite high-gain pedal.

Doug

[Ansil]

I never considered trying the Vox tone stack with the Blackfire. The Vox can do a wicked mid scoop so I bet it would sound good.


FWIW, I tried a JFET simulation of a Soldano once and it sounded just like the Blackfire. The Blackfire sounds really great, my favorite high-gain pedal.

Doug

what about a Fet Version of the Firefly..   Hmmmmmmmm ?

i guess that would be a fet pedal version.. sorry.

[Doug H]

what about a Fet Version of the Firefly..   Hmmmmmmmm ?

i guess that would be a fet pedal version.. sorry.

Using my same brute-force approach to "amp-pedals"... I would guess a minibooster driving a couple jfet stages would be the way to start there, mimicking the freq shaping and etc. Since a big part of the firefly sound is the 12au7 breakup, you may need an output stg too, but I don't know how it would compare, really. It might sound good on its own merit though.

Doug

[Paul Marossy]

How about a Big Muff style tone stack on the Balckfire. Anyone mess with that?

[RDV]

It definitely needs a tone control. I tried mine tonight at the gig and had to go back to the Obsidian(transistor, w/BMP eq), cause it was a bit shrill through the Marshall. I had to make the eq in the Obsidian roll off a lot more treble also(.22uF in place of .0033uF). The way it(Blackfire) is (stock) sounds pretty good through a transistor amp. Brighten's things up. I'm thinking of doing one with the Marshall style tonestack & put it in a great-big box.

I go nite-nite now

RDV

[Mark Hammer]

Although I have a huge bin of previous things that need some troubleshooting and "enclosure-closure", I'm a sucker for things that look like they can be built in an evening.  So, I put together a Blackfire last night.

Hoochie mama, that's some kinda gain.  I'm more of a slowhand player than a flashy, whammy bar shredder kinda guy (though after watching Daniel Lanois on TV last night at the Canadian Liberal Party leadership convention I don't think I play *nearly* slow enough) so I wouldn't think of the BF as my go-to pedal, but it's a nice version of what it attempts to be.  One of the things that I found really interesting about it, though, is that my guitar's tone control has a remarkably profound effect on the pedal's tone.  Normally, I find most distortion pedals respond only minimally to tone control changes from the guitar, generating only modest variations on the fizz.  The BF, on the other hand, sounds dark when I roll off treble at the guitar, sounds Les-Pauly when I put on the neck pickup, and Fendery when I put on the bridge pickup.

I guess what I'm saying is that I'm finding little need for tone controls within the pedal itself that would "tame" it in some fashion, the way the tone on a Tube Screamer is intended to tame it.  Rather, any on-board EQ-ing strikes me as being something one would use for completely revoicing the resulting sound, hence something one would like to be able to easily defeat with a footswitch.  The "ground-lift-bypass" feature of the Fender-type tonestack (which you can't do with a BMP control) is nicely suited to this feature.

[Paul Marossy]

Here's a picture of mine:
http://home.att.net/~u2p0j0m4/BlackFire.jpg

I used a slightly modified Marshall tone stack on it. It doesn't radically alter the tone. But there is some sweet spots with the treble control. Probably a simple low pass filter with a .022 size cap or so would work better? That's what I typically do with my distortion circuits. Maybe moving the tone controls to the same junction as the gain control might have more of a noticeable change in the tone?

Anyhow, the 2N5089s that I used have an Hfe of at least 800. I was testing it last night with about a 13v power supply, and it gets some interesting fuzz tones when you turn the level up and the gain control down. With a 9V battery, it sounds pretty decent. It's susceptible to noise from external sources because it' so high gain, shielded wires may be necessary to help with that. I'm still kind of testing this one out. I made  this one in such a way that I can pull out the circuit and leave the tone control section in place.  

[Paul Marossy]

I've decided that those transistors have too high a gain. I think I will try a hybrid of different transistors with the least amount of noise. I know Joe says that 2N5089s have a gain of around 500, but all the ones I measured have an Hfe of 750 to 800+. My Blackfire has a fair amount of noise.

Anyone else measure their transistors? If so, what did they measure? Maybe mine is picking up noise from some other pedals on my board? Normally, everything is very quiet, but maybe this has more gain than my Boss Metal Zone does...

[RDV]

I've decided that those transistors have too high a gain. I think I will try a hybrid of different transistors with the least amount of noise. I know Joe says that 2N5089s have a gain of around 500, but all the ones I measured have an Hfe of 750 to 800+. My Blackfire has a fair amount of noise.

Anyone else measure their transistors? If so, what did they measure? Maybe mine is picking up noise from some other pedals on my board? Normally, everything is very quiet, but maybe this has more gain than my Boss Metal Zone does...

Try 2n5088.

Regards

RDV

[brett]

My tone control in my Blackfire is simply a high pass filter to ground after the last transistor (10k pot -> 0.022uF cap -> ground).  That gives me a 6dB/octave roll-off with fc tunable from 640Hz to 20kHz.  When turned "up", it cuts as much of the highs out as you want.  Simple and sweet.

PS the output of my Blackfire was originally a bit low (about unity gain), so I changed the 470k/470k voltage divider (which is really 470k/80k because the 100k volume pot parallels the "lower" 470k) to 10k/470k.  Now I have the option of taking a massive signal from it.  (A 100k/470k divider would probably have been more sensible option.)  For the record, I used 2N5089 trannies with Hfe ~620.

[Mark Hammer]

I used 5089's as well, with measured hfe somewhere in the high 600's or higher.

Note that you can often observe similar hfe readings from 5088's and MPSA18's too.  The 5089's, however, are specified as "low noise" units.

Because I had them lying around, I used pretty much 1% metal-film resistors and greeny plastic caps throughout, and I was impressed with how little noise the thing generates, even at full tilt.  I wouldn't ever mistake effect mode for bypass on the basis of hiss, but when you consider that this things sounds like its packing the gain of several cascaded fuzzes into one teeny board, the relatively modest hiss is quite impressive.

Actually, the thing that impresses me the most is how much control over the tone is transferred to the guitar itself.  In most other distortion circuits, I find that noodling with the guitar controls has only minimal effect.  Usually the best case scenario is the classic Fuzz Face descriptor "cleans up nicely when you back off the guitar volume".  Here, I find that my guitar controls can shape the Blackfire's tone considerably.  Enough that switching a pickup and tweaking the tone knob makes it sound like a very different pedal.  Now that T-Boy has fixed my site, I should whip up a sound-clip and demonstrate.

I should point out that the guitar in question is a fake "Nashville" Tele that uses a bi-directional tone control (1meg with .015uf tone cap in one direction, .0047 in the other, and the midpoint of rotation for "off"), and an overcompensated volume control (.001 bypass cap) that rolls off lows when set below about 7.

[Kleber AG]

Hello Mark  
I would LOVE to see (ops...hear) your sound sample!
Yeah, I agree, it's one of the best signal/noise ratio high-gain circuit I've played with, and it's very controlable by guitar's volume pot...


Have you changed something (cap value) or changed some resistor to bias Q2/Q4 colectors at 4.5V?

I have mine with 47n incap and 3.3uF on Q2 emissor to gnd. I had to change resistors at Q2/Q4 colectors to 8.2K to get around 4.5V. I wonder why as I'm using 2N5089s???  :?

Regards
Kleber AG