# DMD2 wet signal could be louder



## stevtron (Sep 23, 2019)

There is a volume loss when the mix parameter is very wet, can I modify that somehow ?


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## Chuck D. Bones (Sep 26, 2019)

Yes, but it requires lifting a lead on IC4 and adding 2 resistors.  Does the volume loss change when you turn the DEPTH control?  Before you modify anything, I'd like to hear from PedalPCB or anyone else who has built this pedal.


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## Robert (Sep 26, 2019)

Some volume drop with this mix control is "normal" (not to be confused with _desirable, _of course).   

The _easiest _way to combat this would probably be a modified algorithm to send a slightly hotter wet signal to the Mix control.


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## Jovi Bon Kenobi (Sep 27, 2019)

I have the same issue with mine. I have been meaning to start a thread.


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## Jovi Bon Kenobi (Sep 27, 2019)

I'm away from the rig but if memory serves me right the volume drop starts right where the delay starts sounding good and strong...maybe 35% up on the depth knob.


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## stevtron (Sep 27, 2019)

Yes, right …  I thought it is maybe possible to power up the second stage of the IC4 (TL072) somehow, without changing the algorithm !?
It's a shame, because this is a really good sounding delay so far …

BTW, same problem is with the Haarp … wet signal too little power ...


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## stevtron (Oct 10, 2019)

I found no solution for this problem … it seems also that the wet signal cuts a lot of higher frequencies too ! What can we do ? If I compare the schematics with other FV1 projects here, I found hat the mix section is very different . Is this maybe the problem ?


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## stevtron (Oct 10, 2019)

Chuck D. Bones said:


> Yes, but it requires lifting a lead on IC4 and adding 2 resistors.  Does the volume loss change when you turn the DEPTH control?  Before you modify anything, I'd like to hear from PedalPCB or anyone else who has built this pedal.



could you maybe specify what you had exactly in mind with your modification ? Lifting wich lead and adding wich resistors and where ?
The depth control doesn't change the volume loss ...


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## stevtron (Oct 11, 2019)

Can I modify the mix section ?  Like this one : https://docs.pedalpcb.com/project/Pythagoras.pdf


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## phi1 (Oct 11, 2019)

The new Pythagoras control will still operate the same (dry signal decreases as you turn the mix knob up). 

In my opinion, a dedicated delay pedal should have a consistent level dry signal, and the mix knob should only control the volume of the wet signal (repeats).  Every PT2399 based delay I've seen is like that.  I think the same idea could easily be applied here.  I'll try to draw up a way to mod the DMD-2 board to this way later with a few off-board components.  

On the arachnid/pythagoras, it's better that the mix knob fades out the dry signal, because for some effects you want only wet.  But those pedals have a master volume control to offset the inconsistent volume throughout the mix knob.  Since the DMD-2 doesn't have a volume knob, I think the mix control should be re-designed.


Another option could be to make R15 a trimmer or external pot for master volume.  Increasing that resistance should boost the overall volume.


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## stevtron (Oct 11, 2019)

OK, thanks ...


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## phi1 (Oct 11, 2019)

Ok here's what I got for a constant dry signal and mix knob only controlling the wet... UNVERIFIED.

You could unsolder the mix pot, then solder wires to the pads (A, B, and C on my schematic), and put the new components on a small veroboard tucked somewhere in the pedal.  Wires from the vero board go to the new mix pot (solder lugs), which is in the same spot as the old mix knob.  Kind of a lot of work, not sure if you want to go through it all.  And I haven't tested this, just going off experience and how PT2399 delay mix knobs are typically wired.  However, on those circuits (example Deep Blue Delay), the op amp following mixing is inverting.  But on the DMD-2 the op amp following the mixing is non-inverting, so there may be a difference in how that works, I'm not quite sure.

If anyone does work this up, or have any critiques, let me know, I might incorporate is into an FV-1 build here soon.


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## stevtron (Oct 11, 2019)

Wow, thanx for your time and work , I'll try it asap ... but with these op amps I see problems too ...


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## Betty Wont (Apr 7, 2021)

Did anything ever come of this? Is there a solution in terms of the algorithm or verified mods?


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## UncleLarry (Feb 10, 2022)

Waking up the zombie thread. I didn't create a new algorithm but what I did do is swap the 10k resistor at R14 for a 10k trim pot. Lowering the resistance here increases the overall output. Most folks will find a "sweet spot" where they like the sound of the delay vs dry signal. Once this is set, you can adjust the trimmer to create unity gain between active and bypassed signal. You could also use a 10k potentiometer to have an external control for this.

You could also do a similar mod at R15, but this has potential to slightly overdrive the opamp, which you may or may not like.


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