cool reverb apart from switch spdt 'pop' issue

[merlinb]

^if i remove R11 / 33k from vb, i lose all verb..
That I don't understand either. At the moment, IC2d is just an inverting amp, just like IC2b and IC3b, so shouldn't need a bias restor to (+) input to function.

The (+) input does need to be connected to Vb, it just doesn't need to be connected through a resistor- a direct connection is better (resistor just adds noise). I think Deadastronaut may have simply misinterpreted and removed the resistor altogether, breaking all connection with Vb.

[therealfindo]

Kick-ass, once you post a final schematic I might work on a layout in eagle if that's OK...

BTW, If anyone was to get some pcbs fab'd, I'd put my hand up for one - I had a headache soldering the self-etched board last time, because of the tiny traces..

[samhay]

^if i remove R11 / 33k from vb, i lose all verb..
That I don't understand either. At the moment, IC2d is just an inverting amp, just like IC2b and IC3b, so shouldn't need a bias restor to (+) input to function.

The (+) input does need to be connected to Vb, it just doesn't need to be connected through a resistor- a direct connection is better (resistor just adds noise). I think Deadastronaut may have simply misinterpreted and removed the resistor altogether, breaking all connection with Vb.

Good point...

Oh, and Rob, have you worked out how to do the switching with this now that it is working.

[deadastronaut]

hi sam, guys..

not yet, spent a day recovering yesterday, celebrated a little too much...(i need to respect that famous grouse whiskey a little more)

anyway,  this will be a lot of fun using a footswitch to play over the trails...and just have a toggle for TB . thats the way i fancy it anyway.

ok, here is what i have now, the basic 'no frills' reverb. without hi/lo switching,

going to try out a tone control instead of that moody damp pot..

[merlinb]

ok, here is what i have now, the basic 'no frills' reverb. without hi/lo switching,

You need a resistor between the volume pot wiper and C1, otherwise the pot can short the (-) input of the opamp to ground. 1k will do.

[deadastronaut]

okey dokey, schemo ^ updated.

notes:

the overall volume works with both reverb and sw2 bypass.

there is oscillation just using the 33k.( R5)


btw i have  3pdt toggle switches too...


edit: correction, vol works only in reverb...

there is a tiny tonal difference between TB and sw2 bypass....but very tiny..

[merlinb]

edit: correction, vol works only in reverb...

If you want a master volumr control that is active all the time, then replace R2 with a variable resistor. I'm not sure why you would want to do this though. Surely you would always want unity gain in bypass mode?

[deadastronaut]

yeah thats not a problem merlin...

i was just making notes for myself really..

[samhay]

I think this will work for the switching (foostwitch on the left).

[deadastronaut]

nice one sam...

thats a mad setup eh..


just been tinkering with the feedback/decay resistors.  33k mass osc/ 100k tameable even fully on. (for more subtle reverb stuff)


so if we went with just buffered bypass, tails...( which i am coming round to thinking that's all i would use in the real world anyway)

no tails =  nasty..

we could make life (switching) nice and simple eh.. ..plus the buffer near the end of my chain might be handy too..hmmm..

thoughts?.

hell we could just use a nice alpha DPDT ..and 2 leds..   (ignore the resistor  values etc)

[deadastronaut]

hmmmm...bummer, i can still notice a tiny pop still when ''playing and switching only''....

doesn't pop when inactive though.....bugger i thought that was cured..

https://dl.dropboxusercontent.com/u/7464107/poppydaybummer.mp3

i'll try 1M resistors to ground on SW 1 3...see if that finally nails it totally. edit( nope)

[samhay]

yeah - the switching idea needs testing and it would be a lot simper if you were happy to do away with true bypass.

Good luck with the pop.

[deadastronaut]

yep i think we'll do away with TB...sounds great as buffered anyway..

apart from this damn @#$%ing @#$%er pop, its only whilst playing though...hmmmm strange...

[deadastronaut]

no love for a poppy switch then?..

heres a clip of switching constantly through silence, great, until you play (which i why i thought it was cured)  then it pops like a mutha with sound going through it,...then disappears as the 'sound' fades off too...

https://dl.dropboxusercontent.com/u/7464107/popperpig.mp3

ive tried 2.2M resistors to ground from out of input and output caps ..as option 2 suggested by RG (geofex)  the 3rd option he gave was 'live with it' 

ive tried 2.2M's from sw2 lugs to ground also....kinda running out of ''not wanting to live with it'' options...

any ideas?.

[merlinb]

it pops like a mutha with sound going through it,...then disappears as the 'sound' fades off too...

Do you still get any voltage on the switch?

[deadastronaut]

0v on both sides...

and 0v when being strummed on both sides..weird!.

[samhay]

What happens if you replace C15 with a smaller (preferably non-polarised) cap?

Edit: Did you true a pull-down resistor from lug 2 of SW2?

[BuGG]

I know it's a long shot, but does it still pop with the LEDs removed from the circuit?

[deadastronaut]

What happens if you replace C15 with a smaller (preferably non-polarised) cap?

Edit: Did you true a pull-down resistor from lug 2 of SW2?

yep tried replacing that cap, no joy..

sw2: . resistor to ground instead of just ground,  yep but still pops and lets reverb through too.


@bugg: there is no led in the circuit yet..(the above switching was for when it was sorted..)


i think we may have to go the electronic switching route...slackers echo base type thing.

I think i have some 4066's..from when i built it.

what about these?..from andrew
http://www.thetonegod.com/tech/switches/switches.html

[samhay]

yep tried replacing that cap, no joy..

sw2: . resistor to ground instead of just ground,  yep but still pops and lets reverb through too.

The cap was a long shot.
I meant a pull-down resistor from the switch side of R21.

Electronic switching is not guaranteed to be pop-free either, but it may be an interesting learning experience.