Dirtbaby (pics and videos)!

[Boba7]

So I finished a couple Dirtbabies lately, one for a friend and one for me.

It's simply the BEST PT2399 delay I've built.

I changed C10 (1,5nf instead of 1nf) and C12 (150nf instead of 100nf) for less noise and a very slightly darker tone (still quite bright!)
R4 is about 30k (raising C12 raised the volume also), and R35 is 56k. C14 is a 47uf tantalum (I read in the notes from valvewizard that using a tantalum in that place was better, so I keep doing it with every PT2399 circuit I build)

The first opamp is a BB OPA2134 and the second one is a OP275.

I added a charge pump to run it at 18v (much better in my opinion!) and also added a couple things:
- a tone switch that adds another 1,5nf in parallel with C10 for a much darker delay
- a slam footswitch with internal trimpot accessible from behind, to decide how fast it ramps towards oscillation.

I recorded two videos to show various settings. Forgive the sound quality, it's just my Iphone recording my little Vox Pathfinder (there's also a Fat Pants at the end of the chain to get a better sound with the amp)

[mrclean77]

Wow - that's a lot going on in there! Now, more than ever, am I feeling a little guilty for changing parts value(s) or adding a tone switch and thinking I'm doing "mods"  You went for the schmorgasboard! And it sounds great to me!

[nzCdog]

Wow... sweet build and neat demos, the phone audio is excellent

[m-Kresol]

Nice, cool demos.

[Boba7]

Thanks guys!

It really is an awesome delay! My favorite! (until the Timelapse? )

[nzCdog]

Thanks guys!

It really is an awesome delay! My favorite! (until the Timelapse? )

I know right?! I am pumped for the Timelapse too!

[jurfin]

I'm currently not quite brave enough to make the leap away from dirt boxes, but when I do, I can't wait to make one of these. Awesome builds that sound really cool and usable in your videos. Nice work!

[lars]

That's it. Need to build this now. Outstanding demo.

[Boba7]

Lars> Glad you liked it!

I'm currently not quite brave enough to make the leap away from dirt boxes, but when I do, I can't wait to make one of these.

It's seriously not a difficult build, as long as you take your time to plan everything well.

I'd recommend to socket all opamps and PT2399 of course, but also :
R4 (feedback resistor. In mine, 33k)
R35 (mod rate. In mine 56k)
R37 (mod depth. Kept it stock in mine)
C8 (just in case, cf build doc. Stock in mine)
C9 and C10 (in mine C10 is 1,5nf, helps with the noise, though it cuts a tiny amount of treble response. Still bright enough for me. Far brighter than the analog mode of my Echo Park, which is supposedly modeled after a DMM)
C13 (will alter the way the repeats degrade, keeping more treble in a tape-like way, cf build doc)

And I definitely recommend a charge pump to run it at 18v. So much better in both my builds!! (and that's the reason I use a IR9022 instead of TL062 for the LFO, since 18v is the maximum voltage allowed for TL062)

[CommGuy107]

Fantastic demos. Thanks for posting.


Sent from my iPhone using Tapatalk

[warriorpoet]

Super cool of you to post all of the mods! This one is in my queue, and I'm going to use most of what you have posted because it sounds so stinking good. Great work!

Quick question:

What does the 18v charge pump do? Doesn't the PT2399 run on 5v?

[Boba7]

What does the 18v charge pump do? Doesn't the PT2399 run on 5v?

Yep, the PT2399 runs on 5v, even with the 18v charge pump. It doesn't affect the chip in any ways. But it affects the opamps, and that made a big difference in both my builds. Running them on 9v there was some distortion happening pretty quickly on the level pot, that was quite bothering to me. 

I'd say try 9v, and try 18v and see what you prefer. My power supply (Cioks Schizophrenic) has an 18v option, so I tried it before putting the charge pump together.

[jurfin]

Lars> Glad you liked it!

I'm currently not quite brave enough to make the leap away from dirt boxes, but when I do, I can't wait to make one of these.

It's seriously not a difficult build, as long as you take your time to plan everything well.

I'd recommend to socket all opamps and PT2399 of course, but also :
R4 (feedback resistor. In mine, 33k)
R35 (mod rate. In mine 56k)
R37 (mod depth. Kept it stock in mine)
C8 (just in case, cf build doc. Stock in mine)
C9 and C10 (in mine C10 is 1,5nf, helps with the noise, though it cuts a tiny amount of treble response. Still bright enough for me. Far brighter than the analog mode of my Echo Park, which is supposedly modeled after a DMM)
C13 (will alter the way the repeats degrade, keeping more treble in a tape-like way, cf build doc)

And I definitely recommend a charge pump to run it at 18v. So much better in both my builds!! (and that's the reason I use a IR9022 instead of TL062 for the LFO, since 18v is the maximum voltage allowed for TL062)

I appreciate the advice, and will definitely reference your notes when the time comes. I have a pile of PCBs to get through first, but we'll get there 

[thesmokingman]

this definitely has me re-motivated to get this build done

[raulduke]

I like the look of these 

Have a kind of utilitarian/Fairfield circuitry look to them (which can only be a good thing).