Author Topic: EHX Freeze tone control mod?  (Read 1316 times)

Lameller

EHX Freeze tone control mod?
« on: March 06, 2018, 03:33:40 PM »
Hi

I would like to add a sinple tone control to the frozen signal of my Freeze. Any ideas on how to achieve that? I think i can get an almost wet signal from the effect volume pot on the pedl but i am not sure what kind of tone control i should add before returning the signal to the volume pot.

Hope this makes any sense??


vortex

Re: EHX Freeze tone control mod?
« Reply #1 on: March 07, 2018, 03:02:19 AM »
I like the Freeze pedal alot but the digital high frequencies on the wet signal are annoying. Is that what you want to tame?

One day I am going to poke around inside the Freeze and see if I can kill off a bit of sizzle with a small cap (to ground).

Lameller

Re: EHX Freeze tone control mod?
« Reply #2 on: March 08, 2018, 10:19:20 AM »
That's precisely what I want to do. Please let me know if you have any luck:-)

Best

Lameller

vortex

Re: EHX Freeze tone control mod?
« Reply #3 on: March 09, 2018, 02:18:36 AM »
Luck?
1) Find a ground point.
2) Locate the fx out lug on the 3PDT switch
3) Take a small cap and bridge them while listening to 'frozen playback'
4) Adjust cap to taste
5) Have fun

mth5044

Re: EHX Freeze tone control mod?
« Reply #4 on: March 09, 2018, 10:28:57 AM »
There’s a thread on this forum describing how to put an effects loop in the Freeze. Follow that thread and you’ll know where to tap into the circuit to get the wet signal. Place a tone control in there!

bartimaeus

Re: EHX Freeze tone control mod?
« Reply #5 on: March 10, 2018, 03:04:22 PM »
That thread suggested placing the fx loop between R3 (removed) and the wiper of the volume pot, but a lot of people had problems with bleed.

I just opened up my own Freeze and checked it out with a probe. It's a pretty complex circuit, and I'm not entirely sure of everything that's going on – I just tried to see what was connected to which lugs of the volume pot, and went from there.

It seems like R3 is connected directly to lug 3 of the pot (the lug that isn't connect to directly to the wiper on the PCB), not the wiper. So it might be possible to add the loop (or a tone knob) by removing R3 and connecting its "send" pad to lug 3 of the pot, and that might do the trick and avoid the bleed found in the other circuit. However, lug 3 seems to be connected to multiple things, which could account for the bleed people encountered, so I'm not sure if that will work.

I may be wrong, but it seems like the wiper of the pot is only connected to C36 (excluding its hard-wiring to lug 1 of itself), so it might be a better idea to place the effects loop between C36 and the wiper of the pot. One could try removing C36, and placing the send/return (or tone knob) across its pads. Before trying that, you could just remove C36 and see if the wet signal is completely muted or not. If it is muted, then it's probably passing across that pad, and you can try wiring up the effects loop (or tone knob).

I haven't actually tested any of this (yet...), but if you're feeling pretty adventurous, these ideas might be worth a shot...




Luck?
1) Find a ground point.
2) Locate the fx out lug on the 3PDT switch
3) Take a small cap and bridge them while listening to 'frozen playback'
4) Adjust cap to taste
5) Have fun

The freeze has an spdt switch, not a 3pdt, and no signal passed through it, so this won't work :/
« Last Edit: March 10, 2018, 03:06:09 PM by bartimaeus »

Lameller

Re: EHX Freeze tone control mod?
« Reply #6 on: March 20, 2018, 03:19:24 PM »
Great ideas!

I will try the last one out and get back if it works. I have rehoused my freeze in an old boss enclosue (i like the boss switches) so everything is easy to get to already.

By the way, the rehouse eorks really well as it is easier to use the freeze as a piano sustain pedal without having an extrrnal seitch takinh up real estate on my small board.

tos

Re: EHX Freeze tone control mod?
« Reply #7 on: October 10, 2018, 01:56:03 PM »
Any luck with any of this? From my analysis:
- both codec IC outputs are connected, first one to R3, second to R2
- they meet at different ends of Level pot ( R3 to free end, R2 to wiper/other end)
- the IC at the top could be some sort of op-amp (really not sure, pinout is not matching any common SOT23-5 I've found), markings: 7Z66D
- top of that 7Z66D IC should be connected to R28, which Im missing right now (could be on the back side), still not sure where that is leading to
- bottom two lugs of the 7Z66D are connected to each side of 2272 via R35 & R34, both seem to be hitting the inverting inputs
- #1 side of dual opamp 2272 seems to be receiving input signal (buffering?) on non-inverting input
- #2 side non inverting input is connected to R35 (mentioned above) via R29

I have some mockup schematics but it is not nice or thoroughly verified. Looking at this network, it seems like there is a better place to lift the signal, have it buffered (nice output impedance) and return it, hopefully, in a much better place.
If you are removing R3, that is exposing output of codec IC to the outside world, not sure if it is made to be done that way (gotta go read the datasheet of that one).
With this amount of op-amps, looks like there could be input/output gain trimmer added (Already got the effect level pot for one side).

Help? Would someone be ready to help if I draw up a schematic?
There would be errors in it but the gist of it would be understandable.

lespos

Re: EHX Freeze tone control mod?
« Reply #8 on: January 29, 2019, 04:58:57 PM »
One of my friends asked me to do some mods on his EHX Freeze. He wants exppression pedal output and FX loop. I'll try to explain how i did it. Sorry for my english, i hope you will understand. There is a bit tricky dry/wet signal mixing. From DAC 19 and 20 pin comes out wet signals. One of them is in phase, other in counter phase (inverted).
There is schematic:



Small IC in SOT23 case is a switch. When switch is on, both wet signals sort of deleting each other. I dont know how to explain this in english. It's just like in arithmetics: -10+10=0, where -10 is inverted signal. When effect is on (IC switch OFF), with level pot we can adjust inverted signal proportion. 

There is my schematic how i realized send/return loop. IC1 must be rail-to-rail opamp. Inverted signal from U1 19th pin is not used. I take signal from U1 20pin, then do all send/retun stuff, and then split it. One goes to other side of R3, other through invertor to other side of R2.



This is how to connect buffers and invertor to main PCB. R2 and R3 on main PCB must be removed.



Some pics of my build:













Link to PCB file (Sprint Layout)
https://drive.google.com/file/d/1Me07ZVUZQzRgAevX-P6W_8cOiqpbJJPg/view?usp=sharing