Fdeck's HPF-Pre

[inefficiency]

Hello fellas.

I play a bit of double bass from time to time, and getting the damn thing loud without it constantly woofing with uncontrollable feedback has always been an issue.

Many guy swear by Fdeck's HPF-Pre, which is an open design for anyone to use - but it would seem that no-one has posted a vero layout for it yet.

Here is the schematic along with a lot of other technical stuff. It would help me a great deal to get this on to vero and I'm sure it would help a lot of other guys out there.

https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxocGZ0ZWNobGxjfGd4OjQyNGJhOWE3YzdjMDY0ODg

[Alex]

CONTENTS DELETED

The author has deleted this message.

[inefficiency]

Awesome! Thank-you very much sir!

I'm sure I could probably figure something out with the LED. I sometimes use my bass with effects, so I might even make this a pedal, so it'll probably be hooked up to a power supply and I can just wire the LED up in the usual manner with a footswitch or just straight to the 9V with a resistor if I decide it doesn't need a switch as it might just always be on.

I'll need to get some transistors because I don't have any of those ones. Do you know anything I could substitute for the 2n4416? My normal supplier doesn't seem to have any and I don't want to get ripped off on ebay...

[johnk]

I drew that one up and posted it quite a while ago, so here's my vero for it:

[inefficiency]

Oh wow. Was that on this site? Nice!

Cheers John!

I've never used a dual gang pot before, is A the top row and B the bottom row with the shaft pointing upwards? Or vice versa?

[johnk]

it doesn't really matter which level you call A or B since they're the same value and both linear.

[inefficiency]

Ok, that makes sense. Cheers John!

[Alex]

Hi!
I've deleted my layout. Easier to use John's since it looks better and it's already verified.

[johnk]

albru80 wrote

Hi!
I've deleted my layout. Easier to use John's since it looks better and it's already verified.

yeah, but IIRC yours was a little smaller.

[Alex]

Only because I've used standing resistors.
Plus I've used GDS for the JFETs' pinout which wouldn't have suited the 2n3819.

[johnk]

a couple of pics of my completed HPF:

[inefficiency]

Neat as always, sir!

[inefficiency]

I've been having some real trouble getting this one working for some reason.

I've tried every transistor combination possible out of the ones listed and when I couldn't get it working I even built a second one from scratch and still nothing.

This is the one build I've done that I have no idea what is wrong.