10 band EQ

[Paul Marossy]

Impressive!   

[byoc]

The biggest problem with multi-band EQ chips is that they're essentially impossible to find for the DIY-er.

IMHO, the reason you don't see more projects of this nature is that it's virtually impossible for the average person to machine the enclosure for the sliders, and it takes a whole lot of trial and error to get all the spacing on the PCB and enclosure just right even when you've got a digital caliper.  And then if someone were to create a PCB transfer for such a project, you'd be locked into a specific brand/model of slider.

An N-band qraphic EQ takes two opamps and N gyrators, or N bandpass filters of one opamp each.

That's basically what the BA3812L is.  Rohm calls them inductors.  And the input buffer/op amp only has one input so you are limited in how you can configure it as a voltage follower.

[byoc]

The biggest problem with multi-band EQ chips is that they're essentially impossible to find for the DIY-er.

What's availability like on the EQ chips?

I am constantly amazed by Small Bear's chip selection.

Steve has 'em for $ 1.75.

http://www.smallbearelec.com/Detail.bok?no=570

That's were I found out about this chip.  I downloaded the data sheet and it look like it was worth a try.

[Izzy]

Which tree man?
I need to get some of them. 

[byoc]

They're made by Xicon.  Mouser has them.  They were used in just about all mass produced pedals since the 80's.  For some reason, some people think they are cheap, but they do make a 2% series with more of the "inbetween values".

[ethanw]

Awesome, I want one! I searched for a true bypass EQ only to find none were available, I'm using a Maxon but I'll buy one of yours when avail!

[joelap]

Wow!  I'd definately be down for one, maybe even two of those!  Great work!