Boss Metal Zone Curiosity

[Paul Marossy]

My Metal Zone seems to pick up hum, so I thought I would change out the electrolytic caps on the external DC power supply and make them bigger. While I had the PCB out, I looked at the components on it, just out of curiousity. I noticed that it had single in-line opamps instead of dual in-line types that you often see. More curious, though, is that some of those single in-line chips were NJM4558D's. I was a little surprised. A nod to the tube screamer, perhaps?

Anyhow, just FYI.

[aron]

More like that's what they use for a large number of pedals. The chip is fairly cheap and available.

hmm.... I never noticed a hum from mine;  but a metal friend took mine :-)

[Paul Marossy]

I think it's my volume pedal picking up hum from somewhere. More experimenting tonight....

[Duff]

What are single in-line/dual in-line/dual/quad opamps?
Can I use the RC4558 for this pedal?

[Paul Marossy]

What are single in-line/dual in-line/dual/quad opamps?
Can I use the RC4558 for this pedal?

Single in-line =  all 8 pins are in one row, and is a single opamp.
Dual in-line  = all 8 pins are in one row, and is a dual opamp.
Dual opamp = a dual opamp, 8 pins, four on each side.
Quad opamp = 4 opamps in one chip, 16 pins, 8 on each side.

Yes, you could use an RC4558 in place of any of those. However, it might be a lot more difficult to layout using only that chip.

[smoguzbenjamin]

Paul, my MetalZone also hummmms like damn crazy, even when I just plug the MT-2 by itself between guitar and amp, no change by using a battery either. Perhaps it's just noisy

[Paul Marossy]

Actually, my hum was caused by my wall wart being too close to my wah, which caused a hum in my Metal Zone... The wall wart moved to the opposite side of the pedal board and now the problem is gone. The way I have the Metal Zone set now, it doesn't hum at all. But, that pedal has such high gain that it amplifies any kind of hum that you wouldn't really normally hear with any other pedal. I don't know for sure that there is a cure for that. Shield your guitar better maybe?