Delay dry volume

[Luke51411]

Would it be possible to add a dry volume pot to this build http://www.grindcustomsfx.com/forum/download/file.php?id=32&sid=c4ff8b80299ef261b7c90af514c8446d
I'm interested in being able to lower and possibly cut out the dry signal to make an interesting effect. Would I just add a pot for R4?

[blackieNYC]

Pot for R4 would work.   A big one.   Might be a different value than the mix pot (the wet level pot) so the two pots might be dialed to weird positions.  Youd have to play with that to have them match up visibly to represent a 50/50 mix.  If you care.   So many pt2399 designs don't offer 100% wet..  I don't have a schematic to link to, but you can bring both wet and dry into a blend pot - maybe 100-500k linear? Dry signal to one end, wet signal to the other, wiper to the inverting input.  Dropmthe mix pot of course. Leave the rest of that feedback circuit there, but replace R5 with a pot or trim pot to make up for the loss due to he added resistor.  I actually chose to do a mixer with two pots. I couldn't get the blend  pot right for some reason.  The dry and the wet each thru 10k pots and 100k series resistors. You could also have a dry channel kill switch, so your choices are all dry, dry with up to 50% variable wet, and the all wet.

[PRR]

[blackieNYC]

Paul - I thought he'd need a rheostat there, but yours is of course better The extra caps are to allow him to ground the dry without grounding the inverting input?  And a perfect match in terms of pot positions
And if I may hijack a little, what would recommend for a blend pot circuit for this? One knob instead of the two?  I couldn't get mine right

[PRR]

Blends are an art-form.

A drawback of mine is that if he sets Wet to zero, and Dry to zero, nothing comes out. That "can" lead to unexpected result (silence instead of a solo). I'm trusting him to keep his head on, his eyes open, and his pots set to useful settings.

[Luke51411]

Both mix pots zeroed would be useful... as a killswitch Thanks for the info I'll have to try adding a dry volume pot.

[samhay]

As an alternative, you could use the original mix pot and wire the end that currently goes to ground to the new 1u cap at the output of IC2A.
This way you can pan between fully dry and fully wet with one pot.

[Luke51411]

Well, I'll be breaking out the breadboard and alligator clips then!

[Luke51411]

Insert Quote
As an alternative, you could use the original mix pot and wire the end that currently goes to ground to the new 1u cap at the output of IC2A.
This way you can pan between fully dry and fully wet with one pot.

I'm confused. Where do I connect pin 1 if I do it this way?

[Luke51411]

I got the method PRR suggested to work and didn't really care for the effect so I unhooked it. I think it might be nice to have a dry signal level when using modulation though maybe I'll try that.

[samhay]

Insert Quote
As an alternative, you could use the original mix pot and wire the end that currently goes to ground to the new 1u cap at the output of IC2A.
This way you can pan between fully dry and fully wet with one pot.

I'm confused. Where do I connect pin 1 if I do it this way?

Instead of connecting it to ground, you connect pin 1 of the mix pot to a new capacitor connected to the output of IC2_A. Same idea as this:
http://www.diystompboxes.com/smfforum/index.php?topic=106854.msg968121;topicseen

As you observed, I am not sure how useful the wet effect would be.

[Luke51411]

I'm good at not being quite descriptive enough. I meant pin. 1 of the ic where the 22k resistor was previously connecting pin 1 and 6

[samhay]

Remove the ground connection to lug 1 of your original mix pot.
Remove R4 (the 22k resistor) and add a cap (1u should be fine) to pin 1. Do not connect the other end of the cap to pin 6.
The other end of the new cap connects to lug one of your orignal mix pot.