madbeanpedals::forum

Projects => Tech Help - Projects Page => Topic started by: zombiesonore on January 18, 2015, 01:16:43 PM

Title: EHX - OLD Low Frequency Compressor
Post by: zombiesonore on January 18, 2015, 01:16:43 PM
Hello everybody,
a friend of mine give this very nice effect.
It works properly but only with battery and I would like to modify it and put a DC jack.
The problem is that I've trouble understanding the wiring and really what kind of current this effect needs.
It use 2 9V Battery and I don't know if it needs 18V or maybe bipolar 9V...
I was thinking using a "road rage" board but if it need bipolar supply, I don't know how to do it...
For info, the switch at the top is an on/off switch.
Can you help me?
Thanks,
Etienne 
Title: Re: EHX - OLD Low Frequency Compressor
Post by: Scruffie on January 18, 2015, 02:04:48 PM
It's bipolar, look at a charge pump datasheet and it'll show you how to do it or someone might have a suggestion for a ready made pump board.

Although... you sure you want to drill in to a vintage EHX pedal for DC?
Title: Re: EHX - OLD Low Frequency Compressor
Post by: zombiesonore on January 18, 2015, 04:17:17 PM
Thanks Scruffie!
I made it works with the -9V and +9V output of the road rage.
QuoteAlthough... you sure you want to drill in to a vintage EHX pedal for DC?
You mean that it will loose $$$ value? How much do you think this effect could be sell?
Not that I'm about making money... Just for my knowledge...
Title: Re: EHX - OLD Low Frequency Compressor
Post by: Scruffie on January 18, 2015, 04:33:24 PM
Wait! Not sure it is bipolar, I have a schematic for a bipolar version and an 18V one.

Can you post a shot of circuit side of the board?

Value... check ebay completed listings, personally, I just think it's a shame to mod a vintage pedal that seems to be in quite good condition.
Title: Re: EHX - OLD Low Frequency Compressor
Post by: zombiesonore on January 18, 2015, 04:42:49 PM
Here is the photo...
Title: Re: EHX - OLD Low Frequency Compressor
Post by: Scruffie on January 18, 2015, 05:04:59 PM
You're good, it's bipolar, phew! :D

Me and Keefe might do a PCB for this (I love EHX stuff so we will) if you wanted to keep it stock...
Title: Re: EHX - OLD Low Frequency Compressor
Post by: zombiesonore on January 18, 2015, 06:02:52 PM
Yes, a PCB would be nice.
Like I've said, I tried to power it with a road rage and it worked, but I felt that the sound was weak...
So I will keep it like it was.
Thanks again.
Title: Re: EHX - OLD Low Frequency Compressor
Post by: TGP39 on January 19, 2015, 11:06:12 AM
Good call. I'm with Scruffie on this one. These old EHX pedals are works of art. You wouldn't want to drill Mona Lisa would you?  Perhaps I could have worded that better!  ;D

Steve.