adding a bright switch to a Deep Blue Delay?

[alange5]

I've built a Deep Blue Delay for a friend and he'd like to incorporate a bright switch.  The switch can either alter the overall brightness, or just the repeats - whatever's easier...

I'm going off this layout:
http://tagboardeffects.blogspot.com/2012/02/mad-professor-deep-blue-delay.html

Which value should I tweak?  The 4n7 cap underneath IC1?  Would tweaking the input cap have any effect?

Thanks

[Mark Hammer]

There is a 22nf/360k pair in the input to the effect.  In tandem with the 180k feedback resistor, this actually drops signal level so that it is roughly half the input level.  By placing a second cap/resistor pair in parallel with the 22nf/360k pair, you can raise the level of higher frequencies without overdriving the 2399 chip.

If you put a .001uf (1nf) cap in series with 150k, and then wire that pair up in parallel with the 22nf/360k pair, that will provide some additional gain for content above 1khz, which should add some additional bite to both the clean and delay signals.

[alange5]

If you put a .001uf (1nf) cap in series with 150k, and then wire that pair up in parallel with the 22nf/360k pair, that will provide some additional gain for content above 1khz, which should add some additional bite to both the clean and delay signals.

Thanks for the suggestion.  I actually ended up putting a cap in parallel with the 47p and using that as the "normal" sound, and switching out the parallel cap for the "bright" setting.  The effect is subtle but noticeable.  I may try your suggestion and compare.

Slightly off-topic - maybe more appropriate in its own thread - but I'm having some trouble with the switching on a modulation daughterboard I've added.  Here's the LFO board:



The modulation switch should yield 3 settings: modulation only / delay / modulated delay.

In position 1, I have modulation. But positions 2 and 3 are just normal delay.  I'm not getting any modulated delay in position 3.

Lug 1 of the delay pot connects to both the main board and the LFO board.  If I remove the connection to the main board, I get modulated delay in position 3, but nothing in positions 1 and 2.

I'm close, but I'm missing something....  Any suggestions are much appreciated.

[Kennt82]

It's very close to the Wampler Analog Echo, also on Tagboard, the main difference being a tone control. Compare the schematics. It may be that 47n between Feedback #1 and 2# that's  doing the dramatic high cut.