cool reverb apart from switch spdt 'pop' issue

[deadastronaut]

cool, cheers sam, 

pcb drilled..populating...

[therealfindo]

cool, cheers sam, 

pcb drilled..populating...

Sweet! Looking forward to hearing how it goes.. I'm going to start populating the board I etched really soon, so still time to make this mod if it works - Good thing I decided on the BB size box, so there's room for another switch

[deadastronaut]

^ did you add the 2 4.7k's and 2 47nf's on your pcb then?...

tip: socket the 33k (the one under the 100uf) ...so you can have the oscillation option too..


populated...

now mass wiring..

[deadastronaut]

well i didn't get time to wire it up at the weekend thanks to mrs astro's wanton need to go to the space station  ..again. 

but regardless of the van allen belt radiation burns and severe muscle wastage and being beaten by small meteorites travelling at over 30,000mph whilst trying to urinate in my suit  i'm on it today...

beep....................................beep.........................................

[deadastronaut]

ok, wired everything up as per diagram/s...

no reverb at all...

the bright/warm switch is working, volume working,

3pdt working....there is a massive vol jump with the tails dpdt when on....but ok when off..

(only thing ive left off is the led for now.....)

hmmmm....

[slacker]

Just had a peak at the layout and the connection to pin 3 of the brick looks wrong, you have it from the inverting input of the opamp not the output.
You will get a volume diff in tails mode unless you match the dry signal level with the true bypass level.

[deadastronaut]

oh f...................

yeah i see what ive done...

son of a @#$%ing mother @#$%ing @#$%er b.......

hmmmm....well spotted man....


edit:


so lookng at my old layout, if i cut the jumper ( above 12-10 pins ) and take it to pin 8 instead should be ok yeah?..

like this...

[slacker]

Looks groovy to me.

[deadastronaut]

okey done that,  we have reverb...yay!!!..

however...

tails switch works on/off..

but i still have reverb when bypassed on the 3pdt....i thought it would trail off reverb when i hit the 3pdt and be able to play clean over the trails....weird.

[slacker]

face palm, I'm a buffoon, I never noticed until now that your feedback signal is taken from after the wet and dry are blended, so even if you kill the input, the dry signal still gets fed into the brick via the feedback pot so you'll still get reverb.
Let me think about it.

[samhay]

Bugger, I should have spotted that too - sorry.
Will have a think about it as well. It is getting a bit tricky, as we don't have any switch lugs left...

[deadastronaut]

 

i knew i should have just built an AB BOX..

[samhay]

What happens if you jumper R17?

[slacker]

You could try taking the feedback from lug 3 of the "reverb" pot instead, that will solve the problem but I don't know how it will change the sound and feel of the effect.
You could also connect pin 1 of R13 to the junction of the R17 and R18 instead of to the opamp's input, this will kill the feedback in bypass solving the problem but you might not get much in the way of tails with no feedback.

EDIT: That might be where Sam is going......

[deadastronaut]

jumper R17

remove the 4.7k and jump it...ok i'll try it.

edit:

removed R17, jumpered it..

nope still got verb on bypass..

[deadastronaut]

hmmmm...

think i'm going to have to scrap this build, and go back to the breadboard with this....what a bummer

oh well..

i'll rip this apart and get it up n running as normal/schemo again,...and then try out some tails/bypass options ...

[samhay]

Before you do that, if you set the feedback to minimum, do you still get reverb in tails?

[deadastronaut]

ok, no reverb when feedback is turned all the way down in bypass

[slacker]

Do you get any tails with no feedback? Just wondering if we can get away with killing the feedback when bypassed or if it would be needed to get any decent tail action.

[samhay]

If so, then taking the feedback from the reverb pot is a good idea. In this case, it might be worth making the feedback pot significantly larger.