cool reverb apart from switch spdt 'pop' issue

[samhay]

yes, BUT you want to put a 1u cap betwen the first op-amp and the first 4k7 resistor and bump up C5 to 1u (or there abouts).

Edit - this won't stop the dry signal in the feedback bleeding into the tails, but it might kill more of leaky reverb in tails.

[deadastronaut]

ok, tried that, 

when not attched to ground i get full verb..

when attached i get verb stil but not as full..but very much still there..

[samhay]

OK.
Perhaps its time to take a walk over to the other forum and have a look at induction's All Star Reverb. This will do buffered tails bypass, at the expense of a wet-only feedback loop, which you may have to revisit.

[deadastronaut]

hmmmm...bummer. , i can never get on the 'other' forum...

cheers though sam.

[merlinb]

Deadastronaut asked me to comment on this design. I haven't been following this thread, so I apologise if I am repeating someone, but:

The tails switch in this circuit won't work, because the reverb feedback path is taken from the output of IC2d.
When Q2 is off, the signal simply passes to IC2d, then back through the feedback pot to the Belton, gets delayed, and mixes back with the dry, ad infinitum (unless the feedback pot happens to be set to zero).

What is it you (Deadastronaut?) are trying to acheive at the moment?

(I'm referring to this schem)
https://dl.dropboxusercontent.com/u/7464107/STANDARDREVERB1.jpg

[deadastronaut]

thanks for taking  a look merlin,

i'm just trying to get reverb 'tails' when bypassed...and dry signal when bypassed, so that i can play over the oscillation/feedback 'tails'..

[samhay]

Hi Merlin - yup, a wet-only feedback has been suggested before.

Rob - this should do most of what you want. You can buffer before and after the brick if you want, but the feedback is the same in my 'Another BTDR Reverb' and works pretty well and you get infinite repeats at max feedback.
You may need to play with a few of the resistors to get the level right.
If you want to see how you can add filtering, take a look at my 'Another BTDR Reverb' thread (http://www.diystompboxes.com/smfforum/index.php?topic=104667.0).

Edit - actually, your 'Bright' switch should just drop-in.
Edit2 - oops - the tails switch is 'upside down'. You want to switch the brick side to Vb in tails to prevent a pop. I will fix this later.
Edit3 - the wet/dry mix is not going to work as drawn, as you will not get unity gain unless it is fully dry. We can fix this with a DPDT...

[merlinb]

thanks for taking  a look merlin,

i'm just trying to get reverb 'tails' when bypassed...and dry signal when bypassed, so that i can play over the oscillation/feedback 'tails'..

You can't have tails AND a wet/dry feeback path. (Unless you make things a bit more complicated- probably an extra opamp needed)
If you want tails, then you have to take the feedback path from the output of the Belton, NOT from the output of the whole circuit.

[deadastronaut]

cheers sam:  i'll give that a go. nice one man.

@merlin: so would the fet switch be better if placed on the output of the brick then?..

[merlinb]

cheers sam:  i'll give that a go. nice one man.

@merlin: so would the fet switch be better if placed on the output of the brick then?..

No the FET is fine. Just move the take-off point of the feedback path (I'm guessing pin-5 or pin-6 of the Belton. I'm not sure what the difference is...)

[deadastronaut]

we tried that before i think..
http://www.diystompboxes.com/smfforum/index.php?topic=101126.msg940338#msg940338

and it cuts short the overall reverb drastically   (however tails switch works fine)

in my experiments if the feedback doesn't go  via pin 14, the reverb isn't the same at all..

[samhay]

I realised in my cut-and-paste haste that there are a few rather non-optimal aspects of the schem I posted earlier - it will be  a lot more predictable with input and ouput buffers to the brick, and I will update it momentarily.

[deadastronaut]

okey dokey...

[samhay]

Just to check. Are you happy with the feedback in this version - http://www.diystompboxes.com/smfforum/index.php?topic=101126.msg940653#msg940653
I ask, as it has wet-only feedback.

[deadastronaut]

wet only?..thats what i have at the mo,

apart from fet switch being from ICB pin 6 etc..


and the wet/dry is fine...though dry isn't dry, but sounds good to me yes.

[samhay]

Schem updated.
I stress that this is untested. It also lacks filtering, so if it works, you will probably want to add a few judicious caps to the wet section.

[deadastronaut]

sorry man, i'm have this on breadboard..

https://dl.dropboxusercontent.com/u/7464107/STANDARDREVERB1.jpg

the other feedback version you linked too that goes to the out of the brick wasn't very good no...

[samhay]

ok, back in a minute...

Schem updated. The only way it will work is if we kill the dry signal to the feedback loop in tails, so we now have a 3PDT doing the switching. I don't know how well this will work or sound, but at least I have designed another another BTDR reverb.

Edit - actually, this is only equivalent when the feedback pot is at max. Othewise, we are feeding relatively too much dry signal back into the feedback. It might sound ok at lower feedback settings, but I will have a think about a better approach.
Edit2 - Now somewhat fixed with a bit of a kludge.

[merlinb]

we tried that before i think..
http://www.diystompboxes.com/smfforum/index.php?topic=101126.msg940338#msg940338

and it cuts short the overall reverb drastically  

That's because that circuit kills the dry AND the feedback simultaneously (so no tails at all, except for what was left in the Belton when the switch was thrown), because the JFET was in parallel with R6.

But in your current incarnation the JFET is in series with R19, so it won't kill the feedback path, so it should work perfectly. Since you already have it on breadboard, it should be easy just to move the feedback take off point and try it out...

wet only?..thats what i have at the mo

You currently have wet+dry feedback, not wet only.

[samhay]

But in your current incarnation the JFET is in series with R19, so it won't kill the feedback path, so it should work perfectly. Since you already have it on breadboard, it should be easy just to move the feedback take off point and try it out...

Pretty sure we tried at some point. I think there is a potential problem with phase cancellation (despite the delay), so taking the wet feedback and feeding it back into the inverting pin of Q3 is not ideal.