This Week on the Breadboard: ENGL Powerball (Bolide) Distortion

[Chuck D. Bones]

The pedal circuit bears a strong resemblance to the Friedman BE-OD line of pedals. I gotta say I like the tone of this one better. Very nice overtones. Good gain range. I was unsure about the EQ section for two reasons:
1. The TREBLE control is tuned very high up in the freq spectrum; turning the TREBLE knob has very little audible effect.
2. The BASS & MIDDLE knobs have enough range to drive the EQ stage to saturation. Not good.

The simple fix for issue #1 is to increase C21 to 1.5nF or higher.
The simple fix for issue #2 is to run this on 18V.

Another option for #2, one which I favor, is to move the VOLUME control ahead of the EQ section.

More to come...

 

[szukalski]

Nice! I have a couple of Engl tube amps and they always have this unique tonal signature. Your description of the high end rings true!

I didn’t even notice there was a Bolide!

 

[Chuck D. Bones]

Every so often, I have to comb thru the sales side of this website to see what's new. This one caught my eye 4 years ago and then was left to languish in my pedal circuit collection. Until now. I have a few mods in mind. Some minor, some not so minor. Mainly dealing with EQ and headroom.

 

[HamishR]

So it uses three dual opamps and the first and last gain stages are on the same opamp. Doesn't this break international safety protocol and possibly lead to the end of the world as we know it? Or have I got that wrong? (Tip: It's highly likely)

 

[Blackboarcult]

It is considered good practice to have first and last stages on separate dual opamps, especially when huge gain increases are present (or so I have read in multiple sources). In my very limited experience, I have only had issues if/when overgained signal is entering the last section, or if that section ups the gain substantially. I guess the biasing network also plays an important role there.

 

[Chuck D. Bones]

Agreed. Arrange the layout and device pairing so that it flows from input to output when dealing with high-gain circuits. With low-gain circuits like a phase-shifter, any opamp pairing is fair game.

First two stages - lower right; middle two stages - lower left; last two stages - upper left.

Knobs (L-R): VOLUME - BASS - MIDDLE - TREBLE - GAIN


Here's the volume mod:


I'm not satisfied with the 3-band EQ, the MIDDLE knob is too broad, it's more like another volume knob.

 

[HamishR]

I wonder if this circuit is designed to sound like an Engl amp or work well with an Engl amp? That could possibly help to explain the EQ choices.

I was quite disappointed with the various Friedman pedals I have tried. They sound kinda unfocused to me, like there's too much going on. Which I guess there is, looking at the schematics. It's a bit odd considering the sounds they're supposedly based on. Is this one better overall?

 

[owlexifry]

I wonder if this circuit is designed to sound like an Engl amp or work well with an Engl amp?

 

[Chuck D. Bones]

Right!
And from Sweetwater:
Plug the ENGL Powerball pedal into your favorite guitar amplifier, and you'll instantly turbocharge it with the paint-peeling high-gain tone of ENGL's Powerball II head. Based on the Powerball II's Lead 2 channel, this distortion pedal employs analog circuitry to faithfully re-create the original amplifier's gain stages. The Powerball pedal gives you a 3-band EQ with ±7.5dB of boost/cut, along with Gain and Volume controls for tailoring your distortion tone. You also get true bypass switching to maintain your tone when the pedal is inactive, along with reverse polarity protection and a second DC jack for easy daisy-chaining. This distortion pedal boasts a durable housing to safeguard against stomp-induced damage. If you want to fortify your clean-voiced amp with metal-worthy dirt, or if you'd like to add an additional high-gain channel to your rig, Sweetwater recommends the Powerball pedal — it epitomizes ENGL's burning modern metal tone.