Mad Professor Sweet Honey drive - OP275 alternative?

[pedalbuild]

The original has an OP275 IC, it is however incredibly hard to source (a real one). What would be a good alternative?

Link to schematic: http://3.bp.blogspot.com/-eWf8bulApFQ/TxAQlYh4VQI/AAAAAAAAAc4/nawMm2aJJ6Q/s1600/SweetHoney_schematic.png

[ElectricDruid]

Welcome!

I'd try any of your favourite dual op-amps and see what you like the sound of. I don't see anything that makes me think that the particular chip they used is critical, although maybe it sounded best to whoever made that decision. The things I've got around that I'd try are TL072, LF353, and 1458. What have you got in the parts drawer? Try it!

[pedalbuild]

Thank you! And thanks for your reply.

How do I know which dual op-amps I can try? Can I use any dual op-amp without risk of damage?

[PRR]

> OP275 IC, it is however incredibly hard to source

Where are you shopping?

Mouser has 2 thousand in stock at under $5.
https://www.mouser.com/ProductDetail/Analog-Devices/OP275GPZ?qs=WIvQP4zGanhBjWhdN34Npg%3D%3D
https://www.mouser.com  - search OP275, PDIP 8

Yes, there's shipping on top. Mouser ships "almost anywhere" but some destinations are steep.

As far as I can recall, "all" 8-pin dual opamps share the old-old '747 pinout; there's not much room for clever variations.

[smallbearelec]

Where are you? I have them:

http://smallbear-electronics.mybigcommerce.com/ic-op275gpz/

Regards
SD

[pedalbuild]

Hmm, yes perhaps I should have specified: can't find one at an acceptable price.

Im in Europe. Including shipping smallbear/mouser would run me 20/25E respectively for a single ic. That's a bit hefty, to say the least.

But even for 5E, that's still quite a lot for an IC, so it's interesting to look at alternatives. If a different IC can get me 98% of the sound for a fraction of the price, that'd be my go to for now. In the case I don't like it, changing an IC is always easy. Tayda used to have the OP275 for 3$, my hope is they get back in stock soon.

But for now, still looking for alternatives. Ideas welcome 

[roseblood11]

I tried a lot of opamps, but stayed with the OP275 in the end. But that was many years ago... I think that opa2604, AD712 and TLC2272 sounded good as well, but the sound was a bit more rounded with the OP 275 at higher gain settings. But it's a diode clipping circuit, the influence of the opamp isn't huge. It's much more important in circuits where the opamp is clipping itself, like the Blackcat OD-1.
https://www.uk-electronic.de/onlineshop/product_info.php?products_id=3207

[ElectricDruid]

How do I know which dual op-amps I can try? Can I use any dual op-amp without risk of damage?

You can use any dual op-amp which uses the same pin out. As PRR said, that really is pretty much all of them. The pin-out got defined years ago, and everyone since has followed the same layout. To not do so at this point would be commercial suicide, since you'd have the only incompatible chip on the market, so everyone sticks with it.

Honestly, have a look. Check the pinout in the datasheets for a few random dual op-amps. You'll find they all put the pins in the same place.

[patrick398]

I build one recently with a NE5532 which i thought sounded nice

Here's a thread which discusses the OP275 and alternatives:
https://www.diystompboxes.com/smfforum/index.php?topic=89988.0

[Fancy Lime]

I would have to hear some good arguments to convince me that opamp choice makes any non-imaginary difference in this circuit unless you use a deliberately unsuitable opamp. The LEDs in the feedback loop mean that the opamp will only clip if the pedal is hit with a relatively loud signal. Input impedance, drive capability, slew rate, and bandwidth are also far from critical. So I would say: use an NE5532 or TL072 or pretty much any other semi-modern opamp with half-decent audio performance. Using different LEDs (different color or even just different makes of red) and different diodes to ground for the clipping will make a much bigger difference.

Andy

[smallbearelec]

Im in Europe. Including shipping smallbear/mouser would run me 20/25E respectively for a single ic.

I can't speak for Mouser. For us, the shipping minimum charge goes mostly to the postal service to cover their losses from delivering letters. The good news is that it covers up to four ounces; that's a lot of small parts. So, if you want the Analog Devices low-noise op-amp, please see if there's anything else you or your friends might need from these shores to fill up the bag.

[ElectricDruid]

I would have to hear some good arguments to convince me that opamp choice makes any non-imaginary difference in this circuit unless you use a deliberately unsuitable opamp.

+1 agree with Andy. The "other stuff" in this circuit is going to make far more difference than the op-amp ever will.

[pedalbuild]

Thanks for the replies. Parts still to come in, but I'm gonna try a handful of different dual opamps. In case I really don't like any of the others I'll try an OP275.