Knockout pedal:possible to mod?Different cutoffs?

[alexlotta]

Hi ,Long Shot as it is forwarded only To EHX Knockout Owners.
I was curios to try that pedal,since is a filter Based Eq.

Do you think is possible To Mod somehow,
adding the possibility to switch between the different cutoff freqs, instead of the fixed Ones (85hz lowpass and 6,5khz highpass).

If cutoff control is on the board no change possible,;
if is on "Fixed Pot ",
maybe would be possible to add a potentiometer to select higher lowpass cutoff (and lower highpass) ,letting things far more interesting to experiment.

If someone could open it and take a pic would be great too.
I believe there no schematics for it around.

[Bootzilla]

It is not digital (I think) so if you have the knowledge you can mod it. If it is a traditional passive filter the cutoff is based on a capacitor value so you could put different caps on a switch. The problem is finding good capacitor values because you can easily go to high or to low.

I don't know how it works because I haven't seen any schems but it is probably possible, just a lot of work (tracing the circuit and adding components for which you need another piece of circuit board etc.).

[alexlotta]

Well I can't draw circuits on boards .I know a mate who can but need schematics.

I asked because similar stuff i have see on the net are usually 2 pots stuff
(example http://www.gitarrenelektronik.de/ind...mart&Itemid=26)
And maybe could be a matter of desolder something fixed ,and to replace with an adjustable pot.
But really dunno what's there inside.
Think i will buy one anyway for curiosity soon.

[Silent Fly]

I know the KO circuit (it is a new version of the EHX Attack Equalizer) and I can't see any way to change the frequencies without changing a lot of capacitors or/and resistors.

[7XL]

Where's a schematic?

[alexlotta]

Since Silent Fly said that , i think that calls for the answer at my question.

Originally Posted by 7XL

Where's a schematic?

Also he mentioned,. before it was not called "knockout".
Based On that ,by googling i found the schematic of the Original "NOT-KO" version ,here:


Dunno How Differs from Reissue Though, at least Pots have different names and there is an on/off switch back, so i think is not quite the same




..Sure I like The old "Angled-Box "Style more (side profile view of the pedal ) .The one here:
http://www.tonetweakers.com/images/u...h_attack_c.jpg

[Bootzilla]

It seems like the top row is just a lot of low pass filters in a row so if you want to change the cutoff of the fundamental or lowpass you have to change the capacitors to ground (C6,C7,C8 and C2,C3,C4)

The Bottom row is the highpass or attack part and here you should change the capacitors between the resistors to ground (C10 till C15).

To find out if you need higher or lower values just search the electronics forum on passive tone control (the tone knob on your bass is a low pass filter) and high pass filter (it is basically an opposite low pass filter). I would first only switch one cap in each part and preferably one somewhere in the middle (just to be safe).

Im not 100% sure on this and I'm just guessing that the circuit works like this. I'm no expert on electronics.

edit: I think that the knockout is the same as the attack eq or at least similar enough to make these statements. They probably tuned it a bit with one or two different values and improved the bypass or something like that (maybe just left it all the same). The rest will probably work exactly the same.

[7XL]

It appears to be a dynamic EQ. The above description is correct for the most part. To change the cut off frequency would require switches and/or potentiometers depending on what you are trying to achieve.

Judging from the schematic you can get pretty carried away with tweaks on this pedal. I don't have one to mess with , I can see how you can add 4 * 3 pole rotary switches and 12 trimmers to tune this pedal in a few different ways.

[alexlotta]

Did'nt expect follow ups.
Well i can't change anything myself but i 'm going to be partially endorsed by a guy who does pedal stuff and could sort out,once i tell him what i want exactly.

?After the lowpass there is a gain or a control of peak resonant "a la" Acg ?(the filter onboard preamp).
_

To change the cut off frequency would require switches and/or potentiometers depending on what you are trying to achieve.

Well the aim would be to change the frequencies to experiment with different emphasis ,
From going away from the "dub territory" in one case,or

to "Extend" the Original Porpouse of the pedal ,
to interact with the pickups and to change the "charachter" of them ,with resonant frequencies more closer to bass pickups :since is thought for guitar i imagine it would'nt work In that way with a bass like it is.
A continuos pot maybe could do that ..no clue how to do it though so can't be more "deeper" about.

Thanks for the info about the schematics ,good to know .