freestompboxes.org

who have gut shots of the Rothwell Hellbender?

is a great pedal for AC/DC

web shoot

Rothwell Hellbender, Any news?

Looks like the clipping circuit is 2 Zener diodes back to back in the op amp feedback loop; this type of clipping is supposed to give "tubelike" overdrive tones.

Jack Orman explains how it works in his diode clipping tutorial here: http://www.muzique.com/lab/zenmos.htm

The Hughes & Kettner Warp Factor is an example of a guitar overdrive pedal that uses lots of zeners for clipping.

This looks a lot like the first clipping stage of the Warp Factor.

Cool thanks! It sounds really good to me in some of the demos.

blackbunny wrote:Looks like the clipping circuit is 2 Zener diodes back to back in the op amp feedback loop; this type of clipping is supposed to give "tubelike" overdrive tones.

Jack Orman explains how it works in his diode clipping tutorial here: http://www.muzique.com/lab/zenmos.htm

The Hughes & Kettner Warp Factor is an example of a guitar overdrive pedal that uses lots of zeners for clipping.

This looks a lot like the first clipping stage of the Warp Factor.

don't those 3 pin SMD diode devices usually have 2 diodes per package? seeing as there are 2 of them, wouldn't that make it 4 zeners in the fb loop? I'm not all that familiar with everything SMD, but I know I have seen those dual diode packages before.


btw- it really bugs me when these demos show the "clean" signal, and it is totally distorted. I wouldn't trust that demo at all to show you what this pedal really sounds like.

RnFR wrote:don't those 3 pin SMD diode devices usually have 2 diodes per package? seeing as there are 2 of them, wouldn't that make it 4 zeners in the fb loop? I'm not all that familiar with everything SMD, but I know I have seen those dual diode packages before.

Now that you mention it, there could be either single or dual zeners in each package.
The single zener package is usually a SOT23, which has pin 3 (the one on it's own) as cathode and pin 1 (lower left if pin 3 is facing up) as anode.

The AZ23 package looks identical and has 2 zeners, pin 3 is common ANODES, pin 1 is cathode 1 and pin 2 is cathode 2.

These come in the full range of voltage values, so you need to decode the markings on the device.
If pin 2 is not connected or shorted to pin 1, you can assume it's a single zener.

RnFR wrote: btw- it really bugs me when these demos show the "clean" signal, and it is totally distorted. I wouldn't trust that demo at all to show you what this pedal really sounds like.

AGREE!
Are you refering to the PGS demos? Those bug me. They're better produced than some demos online, but they play everything through small cranked tube amps;
"here's my clean tone: CKRRUNCH!!!"
- makes every OD sound just like their amp. - It's not a bad sound, but it's not the only sound, & doesn't tell you much..
(& then there are the countless thousands of videos with people using a crappy camera mic, 30' from the amp, usually with the gain & treble knobs maxed, not only doesn't tell us anything, but
- hurts my ears!!)
- but I've heard some better quality demos of the Hellbender, & it does sound promising..

matt239 wrote:

RnFR wrote: btw- it really bugs me when these demos show the "clean" signal, and it is totally distorted. I wouldn't trust that demo at all to show you what this pedal really sounds like.

AGREE!
Are you refering to the PGS demos? Those bug me. They're better produced than some demos online, but they play everything through small cranked tube amps;
"here's my clean tone: CKRRUNCH!!!"
- makes every OD sound just like their amp. - It's not a bad sound, but it's not the only sound, & doesn't tell you much..
(& then there are the countless thousands of videos with people using a crappy camera mic, 30' from the amp, usually with the gain & treble knobs maxed, not only doesn't tell us anything, but
- hurts my ears!!)
- but I've heard some better quality demos of the Hellbender, & it does sound promising..

I think Rothwell's own demos are about as good as any I've seen. Concise, good sound and covering a lot of territory.

I like this one:

They never reference the clean signal, but it sounds pretty clean when they lower the gain on the pedal. - Sounds sweet!

TL072, zeners in feedback loop, & I guess, some careful tone shaping..
I'd guess they're using both halves of the TL072?
- I wonder if the diodes are in the loop of the first or second stage?
- I wonder if the TL072 clips even w/o the diodes? (as in a Sansamp..)

matt239 wrote:I like this one:

They never reference the clean signal, but it sounds pretty clean when they lower the gain on the pedal. - Sounds sweet!

TL072, zeners in feedback loop, & I guess, some careful tone shaping..
I'd guess they're using both halves of the TL072?
- I wonder if the diodes are in the loop of the first or second stage?
- I wonder if the TL072 clips even w/o the diodes? (as in a Sansamp..)

There's some LEDs in there too, maybe to ground after a second gain stage...

The board layout looks pretty much identical to Switchblade. I think there must be more differences than just one clipping pair though..
viewtopic.php?f=7&t=20613