MUFF WIGGLER Forum Index
 FAQ & Terms of UseFAQ & Terms Of Use   Wiggler RadioMW Radio   Muff Wiggler TwitterTwitter   Support the site @ PatreonPatreon 
 SearchSearch   RegisterSign up   Log inLog in 
WIGGLING 'LITE' IN GUEST MODE

EHX Cathedral CV mod
MUFF WIGGLER Forum Index -> Modular Synth General Discussion Goto page 1, 2, 3, 4  Next [all]
Author EHX Cathedral CV mod
anselmi
I got my Cathedral reverb/delay pedal modded by a guy who put CV control of delay time and infinite/tap button

here´s a demo of the delay time controlled by the tame machine´s CV2 output in loop mode...a granular lab! SlayerBadger!

[s]http://soundcloud.com/anselmi/ehx-cathedral-cved[/s]
the83
Sounds AWESOME. Wish you had a schematic or something.
mckenic
Great demo! Wicked sounds!

Wow!

Been thinking of the Cathedral for AGES but if I could do a mod like this on it - it would be a no-brainer!

LOVE the sounds you got! thumbs up
anselmi
I don´t have an schematic since I don´t performed the mod...I barely can solder a cable! Dead Banana

But some EHX guy told me that the entire process is a DSP that read positive voltage at different points, comming from a 5v source. The knobs acts as attenuators and that´s all

So breaking the voltage track before the knob will replace the internal +5v source by an external one and you can use each knob as an attenuator for the incomming signal

BUT the DSP could be damaged with both higher than 5v voltages or negative ones, so the technician that did the mod made a little board that limits and rectify the incomming signals in order to keep it in the safe zone

Also he conect it the way the knob is no longer an attenuator but an offset control and also setsthe minimum value of the parameter
zvukoprocessor
very good! thumbs up
Joe.
mckenic wrote:

Been thinking of the Cathedral for AGES but if I could do a mod like this on it - it would be a no-brainer!


It's the simple Voltage clamping/limiting/clipping circuit as shown on Doepfer's DIY page:



2 Diodes for limiting the voltage and preventing reverse voltage, and a resistor for current limiting.

You can easily do the mod yourself, so go get a Cathedral thumbs up
abstraktor
LoFi Junglist wrote:
mckenic wrote:

Been thinking of the Cathedral for AGES but if I could do a mod like this on it - it would be a no-brainer!


It's the simple Voltage clamping/limiting/clipping circuit as shown on Doepfer's DIY page:



2 Diodes for limiting the voltage and preventing reverse voltage, and a resistor for current limiting.

You can easily do the mod yourself, so go get a Cathedral thumbs up


you'd need this protection circuit for every individual CV in mod?
anselmi
Another one, now processing modular drums and using the MFB dual LFO square wave to activate the "infinite" button...tame machine´s CV2 again controlling delay time in loop mode

[s]http://soundcloud.com/anselmi/ehx-cathedral-cved-2[/s]
Votek_Mendo
SlayerBadger!
mckenic
Bloody BRILLIANT mate! Really inspiring stuff - LOVE how you end it!

thumbs up

Really, really inspirational - next on my list - Cathedral!

Damn! very frustrating

hihi
solaris
uh wow, really nice chaotic bouncing and dense swarms.

Will this mod work on a Holy Grail as well?
anselmi
solaris wrote:
Will this mod work on a Holy Grail as well?


I think yes but for controlling reverb time I´d use a VCA and CV decay module instead
pricklyrobot
Hmm, I wonder if I could use this same scheme to send the Expression/CV In on my (non-Deluxe) Memory Boy to other destinations...
Monobass
anselmi wrote:
But some EHX guy told me that the entire process is a DSP that read positive voltage at different points, comming from a 5v source. The knobs acts as attenuators and that´s all


certainly seems to be the case with my Stereo Memory Man with Harazai too applause

just took it apart and all the knobs apart from the Harazai (encoder) are just attenuators on the same voltage source.
Monobass
LoFi Junglist wrote:
mckenic wrote:

Been thinking of the Cathedral for AGES but if I could do a mod like this on it - it would be a no-brainer!


It's the simple Voltage clamping/limiting/clipping circuit as shown on Doepfer's DIY page:



2 Diodes for limiting the voltage and preventing reverse voltage, and a resistor for current limiting.

You can easily do the mod yourself, so go get a Cathedral thumbs up


So in this case U2 could be the DC voltage normally connected to the pot and U1 is an external input?
Joe.
U2 is the positive rail and U1 is ground.

1 sec I'll fire up Eagle.
Joe.


A is how the pots are wired (use a multimeter to see which is gnd, which is 5v), B is how you can replace the pot.

You'd need to make a board with a summing circuit to add the original pot voltage to the CV input voltage, in order for the old pot to be used as an offset. (the offset could only be positive, and the CV input would only respond to positive voltage between 0-5v).

The simplest implementation would be to have the CV socket normalised so that when there's no input the pot is used, when a cv jack is put in it disconnects the pot.
Monobass
yeah good call on the socket normalisation, gonna try this tonight I think, thanks thumbs up
mckenic
Monobass wrote:
yeah good call on the socket normalisation, gonna try this tonight I think, thanks thumbs up


Please take lots of pix - cant read schematics to save my life!
Monobass
well it works thumbs up tried it on the filter pot of my EHX Stereo Memory Man.

I wired it up with a switching jack as LoFi Junglist recommended so that when nothing is plugged in it acts normally*... and when there is something in the CV input the pot then becomes an attenuator for the CV input.

* I used diodes that I happened to have to hand rather than Schottky diodes (which I have somewhere but I can't find them) anyway what I've found is that in 'normal' operation I'm not getting the full 5v through even when the pot is fully open, it's dropped down to 4.5v.

I'm assuming that's due to the forward voltages of the diodes or something?
Monobass
oh the only other difference LoFi Junglist is you have the current limiting resistor on the 'out' side, which is what I did. On the Doepfer diagram it's on the In side.. but that'll only account for a current drop right, not voltage?

edit: oh and yeah I'll upload some pics tomorrow.
itijik
Great information, guys. Nice digging thumbs up
DGTom
I thought the resistor had to go on the "in" side as well hmmm.....

My idea was to do a passive mix of the pot & the external voltage & then have the limiting diodes. It would really be usefull to have the pot remain an offset I think.

@Monobass pictures of the guts would be great, I'd love to see how much room there is inside before I buy the pedal just to do these mods, the gate in on the Infinate is woah
Joe.
Pic (stolen from freestompboxes.org) of the Cathedral.



DGTom
Cheers! Heaps of room. Awesome.
MUFF WIGGLER Forum Index -> Modular Synth General Discussion Goto page 1, 2, 3, 4  Next [all]
Page 1 of 4
Powered by phpBB © phpBB Group