Cool video on Designing an Overdrive Pedal

[jugglindan]

Brian Wampler just released an interesting video on designing an overdrive pedal from scratch. Might be interesting for us DIY pedal types. I am watching today but if I have time after work I might have a crack at breadboarding the circuit along with the video.

[Andy40]

Great Vid. Watched it all the way through. Maybe one day I'll get to play around a bit more like this on the breadboard.

[Joe Garfield]

Sometimes I wish I wasn’t such an (anti) op-amp snob =). But that looks like a fun project to try!

[jugglindan]

Sometimes I wish I wasn’t such an (anti) op-amp snob =). But that looks like a fun project to try!

I find it interesting to read forum posts by people asking something like "what pedals did Tony Iommi* use on Paranoid?" only to be surprised that most of the answer is "none, they just recorded the amp at hell raising volume". But for those of us who can't just crank a tube amp, op amps, pedals, and modelling amps are a good solution.

But hey, at least op amps are still analog. So it's possible to embrace op amps and still turn your nose up at digital

Myself, I love a good op amp. They are the basis of most dirt pedals on the market (except maybe for fuzz).

[Joe Garfield]

(Edit: hopefully this isn’t taking away from the thread - it looks like a cool project!)
Good points - my shortcoming (well, one of many) is not knowing what a ‘good’ op amp is. I know they exist in recording studios and stuff, but I also know cheap consumer ones can sound like crap.

Maybe in a pedal it doesn’t matter as much, and ‘cheap’ op amps might even have desirable sound!

I wonder if one of these would work:
https://sparkoslabs.com/discrete-op-amps/

Thanks for the link - I’ve never built a pedal and this looks like one I might try in the future.

[jugglindan]

(Edit: hopefully this isn’t taking away from the thread - it looks like a cool project!)
Good points - my shortcoming (well, one of many) is not knowing what a ‘good’ op amp is. I know they exist in recording studios and stuff, but I also know cheap consumer ones can sound like crap.

Maybe in a pedal it doesn’t matter as much, and ‘cheap’ op amps might even have desirable sound!

I wonder if one of these would work:
https://sparkoslabs.com/discrete-op-amps/

Thanks for the link - I’ve never built a pedal and this looks like one I might try in the future.

It's not taking away from the thread at all. I enjoy these conversations wherever they might lead. While expensive op amps with "better" specs definitely exist (lower noise, tighter tolerances etc), they are not always that helpful in effect pedals, particularly overdrive pedals. My $200 modded tubescreamer sounds fantastic, as does my Barber CDD that I build recently. The op amp in both cost less than $2. I swapped them for a $0.30 4558D op amp I bought on eBay and couldn't hear a difference. In soft-clipped overdrives, the clipping diodes can make a much larger difference to the sound. In fact, it's all the stuff that surrounds the op amp (tone circuits, filtering capacitor choices, clipping diodes, number of gain stages etc) that makes most of the difference in sound.

Also this:

[Joe Garfield]

That makes sense - also the whole point is to add dirt! My bias came from putting together a hi-fi audio system for music (hybrid dual triode /discrete AB power with discrete resistor ladder converter) but it’s probably not the right approach to think what’s good for one is good for the other. Also the second video reminded me that guitar amps / cabinets naturally roll off high frequency which is where (I find) op amps show their shortcomings, so actually it’s probably the ideal place to use an op-amp!

[jugglindan]

Ah yes, high end hi-fi is another thing altogether. The stuff I build is decidedly lo-fi

[Simon Barden]

An op-amp is an op-amp. It does what it does very well within its designated limits. That is, amplify a signal cleanly and with very low distortion. They all have slightly different operating parameters and need different support resistors and caps to make them work properly, but once you do, they work with very low noise and distortion (except maybe some of the early op amps like the classic 741, which was rather noisy).

Those discrete op-amps are basically a waste of money. They certainly aren't a drop-in replacement for the majority of existing op-amps, which will be chosen for their specific attributes, such as bipolar or jfet input stage. They are obviously much larger and so are unlikely to fit in as a replacement anyway. And as standard op-amps are so good anyway, any small improvement in the %THD figure would never be heard.

Good points - my shortcoming (well, one of many) is not knowing what a ‘good’ op amp is. I know they exist in recording studios and stuff, but I also know cheap consumer ones can sound like crap.

Maybe in a pedal it doesn’t matter as much, and ‘cheap’ op amps might even have desirable sound!.

I think you are getting mixed up between an op-amp and a pre-amp.

Almost all op-amps are cheap, typically well under $1 each when bought in bulk. They are just small chips, typically with 2 op-amps within each chip (though many other configurations are available). Most (unless designed for a specific purpose) have a bandwidth of at least 100kHz (and it is generally far greater), so it's not the op-amp that looses high end, it's the rest of the circuitry. And in the majority of drive pedals, the op-amp output signal remains clean, and is just used to raise the signal level into other devices that provide the actual distortion.

[Joe Garfield]

Either that, or it’s all the snake oil I was raised on It was either that or Diet Coke. Apparently if you drink enough of it, you hear magical things that don’t really exist. =)

Do these breadboard DIY pedals fit inside normal size stomp boxes?