CHASM REVERB

[pinkjimiphoton]

proud to announce the birth of yet one more chasm reverb. despite a long and arduous birth at the hands of a rather inept doctor, the patient has survived the operation and sounds great.

i looked at it again. hard. went over the entire trace side of the pcb and scratched between every trace, every node. plugged the reverb in.


silence...and then the airplanes arrived.

to build the photonic airplane simulator.... details below. it's really cool if you have an azimuth coordinator sound system. i digress.

i was like, @#$%!!!!!!!!!!!!

so i went out and smoked a while. cleared my brain. come back in, now entirely sure the wiring was right, entirely sure there were no bridges, broken traces or dead chips/fets. what the hell could be wrong?


well... i finally start looking at the top side of the board, component by component. that was when i noticed the big mistake. i will take lumps for it. i deserve them, cuz it was stupid. epic stupid.

on either side of rob's layout of the regulator are two 10 k resistors. above them, another that is horizontal. these are in the feedback path of the circuit

i remember pulling out the last of a small bag of 10k resistors, not even looking at them. i generally populate all of each value as i go. these were all definitely in the same bag, that's why i grabbed it.. it had a couple, and i figured cool.

well, 3 of them 10k's were actually 1k's. i'm betting the guy who packed them made the same mistake as i did, cuz man, looking at them and the 1k's they look almost the same. VERY subtle difference.

i replaced those with 10k's, reconnected the long-suffering brick, which was put thru the digital mole station of it's life (digitals as in fingers) and hooked up wrong intentionally and everything, and STILL works.

it sounds great... even the dang smoked pot still works. and it was cool, i got to watch the light show when i let the smoke out of it.

still using the original 805! it's working fine.

so.... if ya want the patented jimi photon airplanes in your head real attrociously @#$%ing loud pedal, change them three resistors to 1k and let 'er rip.





anyways, with just THOSE THREE CHANGES, YOU can have YOUR OWN AIRPLANE SIMULATOR PEDAL!!! SO ALL YOU COMERCIAL BUILDERS!!!! TAKE THIS BROTHER MAY IT SERVE YOU WELL!!!



seriously nice sounding box rob... thank you so much!!!
and thanks mike for burning me out a board

and all you guys for the support, education, humor and putting up with my idiot self while i found this.

stupid pedal trick of course will be imminent. with fuzz and without.

[pinkjimiphoton]

oh shoot, just noticed too when i was trying to debug, i changed the .47 cap to .047.... guess i gotta fix that too... makes for a nice clear verb, but i bet it's gonna be a big improvement.

<epic facepalm>

[samhay]

cool (the getting it going rather than the face palm and whatnot).

[pinkjimiphoton]

thanks sam!! 

[deadastronaut]

brilliant!...now you can relax and chill a little..



the 1k mod..

[pinkjimiphoton]

yes, the "mod"...... 

[loylo]

Glad you sorted this out! 
I know that guys who advise to check the components' value may sound like morons when you're convinced the problem lies elsewhere. And then you check for the tenth time, facepalm! Been there so often!!! 

In fact, along the two "1K" resistors in the feedback loop, the third "1K", forming the voltage divider for Vref, was certainly another part of the problem as it made Vref way above 1/2 V+   

[pinkjimiphoton]

Glad you sorted this out! 
I know that guys who advise to check the components' value may sound like morons when you're convinced the problem lies elsewhere. And then you check for the tenth time, facepalm! Been there so often!!! 

In fact, along the two "1K" resistors in the feedback loop, the third "1K", forming the voltage divider for Vref, was certainly another part of the problem as it made Vref way above 1/2 V+   

the funny thing is i was describing exactly what would happen there.... <shakes head>

i was so obsessed with looking for shorts, i forgot to check topside.

[Jdansti]

Looks like the "pot" wasn't your problem... The "pot" actually helped you solve the problem!

[haveyouseenhim]

I'm glad you got it sorted Jimi.

I'm really glad it wasn't my boards fault 

[pinkjimiphoton]

lol.... the board is good mike, no worries.

i still have two problems...one, i need to find a good tl074 or 84, i have an lm324 in there right now and either it or the brick is a little hissy.

after the abuse they both sufffered, i can't blame them for having PTSD a little.

the other problem, is the volume goes all the way to zilch, which it wasn't doing before. but hey, i can live with that.

i don't wanna have to go back in there again!! lol... trimmed wires as short as possible, some broke off while i was tinkering. that made fixing them difficult.

but that said, nice job rob, this thing sounds wonderful!!

thanks again rob for the circuit, mike for the board, and all you guys who helped me.



complete with cool-ass purple ultraviolet led..



i opted to make the osc footswitchable, cuz i had some spdt footswitches and didn't feel like buying some pos at rat shack!!

it's cool, tho, no pops or anything.

[bluebunny]

Nice result, Mr. P.  You should call it the "Dreamliner Reverb".  Both are aircraft that catch fire!   

[chi_boy]

Has anyone tried an ON/OFF/ON switch for the OSC Switch?  I haven't found specifically that an ON/ON is called out, but in reading the thread, that seems to be the default.

I was comparing the Rub-a-Dub Reverb and the Chasm and it looks like the OFF position would make the Chasm similar to the Rub-a-Dub, meaning no feedback loop.

I curious if that would yield a different type of sound, or would the change be negligible.

-George

[loylo]

The feedback pot shunt the feedback signal to the ground, so the feedback pot at 0 is similar to the Rub a Dub. There is no need of an on/off/on switch.

[chi_boy]

The feedback pot shunt the feedback signal to the ground, so the feedback pot at 0 is similar to the Rub a Dub. There is no need of an on/off/on switch.

Ugh, should have seen that.  Got too distracted by the shiny object.....

Thanks!

George

[Maik]

Ready now!
Thanks Rob
https://app.box.com/s/176c4lunl1te0mjbyewg
https://app.box.com/s/39sayal2fud0ewu4bqzr

[deadastronaut]

^

cool, nice one maik.

[Circusbrains]

I was so excited by my latest build that I wanted to share it with you guys.
Thanks, Deadastronaut!

[Circusbrains]

[deadastronaut]

 

nice one man.