5-Band Fully Parametric EQ

[aziltz]

Yeah, Taylor is actually who prompted me to consider the fab'd boards.  It's a money issue for the time being, but its something I would definitely like to try.  As soon as this design is verified though, I should be able to make a few etched boards using this layout.

[jkokura]

I have no idea what it would cost, but I too have little free cash right now. Plus you're moving. Keep us posted about what you're up to.

Jacob

[gigimarga]

Congratulations (and thanks) aziltz for your very nice work!
Can you post a ready for transfer PCB of the last version?

[aziltz]

Congratulations (and thanks) aziltz for your very nice work!
Can you post a ready for transfer PCB of the last version?

sure, I can do that later tonight. But be warned, it isn't fully verified yet. More on that later.

[gigimarga]

OK...thx a lot!

[aziltz]

Here's the transfer for the most recently posted schematic and layout above.

The Caps without values can be varied to change the frequency ranges.  I'll have to dig up my notes over the weekend on what I've been setting them too, but for starters, read this article by RG.  http://geofex.com/Article_Folders/EQs/paramet.htm

[gigimarga]

Thank you very much aziltz!

[aziltz]

not a problem.  If you try it before I do, please let me know.  I am a few weeks out from verifying it.  I'll need to order some components first.

[aziltz]

minor arrangement updates.



If anyone is interested in the original 5 band fully parametric project, I have a few leftover transfers, I could make a PCB or two.  I'll probably have time early next week.  This is the first, squarish layout on the first page of the thread.

[jkokura]

I've been silent for too long regarding this.  Apologies to all who were interested.  Here's the current circuit I'm working with.  High and Low Bands have been changed to Bax-type Shelf, with variable shelf roll off in the treble.  No board yet, but when its done I'll be offering to make a few.

I've eliminated the input and output gain stages and trimmers.  Headroom has been increased to 18v and I've hopefully simplified the operation a bit.

Austin, since I'm guess you've become an expert at it, I'm hoping you can help me understand part of the schem. I'm trying to redraw it for just three bands with no shelf either on the Treble or Bass end. The hope is to then make a PCB layout with just the three bands (Bass, mid and treb) with all Cut/Boost, Freq, and Q all being Board mounted pots. At least, that's what I'm trying to do. I'm building the schem in Eagle, and then my hope is to do the layout in DIYLC.

So, if I wanted to remove the treb and bass shelf, is it as simple as removing the resistors and connections from VD and VC, and then just not including the Bass and Treble componants in your Schematic posted?

Jacob

Essentially what's happening is that you've got the

[aziltz]

I've been silent for too long regarding this.  Apologies to all who were interested.  Here's the current circuit I'm working with.  High and Low Bands have been changed to Bax-type Shelf, with variable shelf roll off in the treble.  No board yet, but when its done I'll be offering to make a few.

I've eliminated the input and output gain stages and trimmers.  Headroom has been increased to 18v and I've hopefully simplified the operation a bit.

Austin, since I'm guess you've become an expert at it, I'm hoping you can help me understand part of the schem. I'm trying to redraw it for just three bands with no shelf either on the Treble or Bass end. The hope is to then make a PCB layout with just the three bands (Bass, mid and treb) with all Cut/Boost, Freq, and Q all being Board mounted pots. At least, that's what I'm trying to do. I'm building the schem in Eagle, and then my hope is to do the layout in DIYLC.

So, if I wanted to remove the treb and bass shelf, is it as simple as removing the resistors and connections from VD and VC, and then just not including the Bass and Treble componants in your Schematic posted?

Jacob

Hey Jacob, its very easy to turn this into a 3 band like you want.

Essentially what's happening is that you've got the oversauced do-hickey interfaced with the right-angle PVC flux capacitor which bypasses the operational resistor.  In turn this causes the thing with the stuff to act more like the stuff with the thing.

Drop everything between Vd and Vc, which is the 50k bass shelf and 25k treble and everything attached.  Also, drop R10 and R5 and that should do it.

I should note, soulsonic suggested that a 9v zener at the DC input would save the MAX1044 from certain death more so than the 1N4001 alone.

Anyway,

[jkokura]

HAHAHAHAHAHAHAHAH!

That made me laugh out loud. So much so, my daughter was startled (she's six months) and my wife wanted know what the heck was going on in here!

I figured that was the answer. Now I've drawn up the schem in Eagle, but I suck at doing layouts, so that's gonna suck.

Jacob

[sst4270]

Jacob,

I've been following this thread and I too am interested in building the 3-band version. I would be happy to do the layout if you can send me the schematic you've come up with...

Thanks in advance,

Steve

[gigimarga]

Hello aziltz,

I hope to have some hours to build your parametric EQ (thanks fot sharing it!).
I've read all the topic, but I found only some values of the caps for bass guitar.
Can you post a set of values for guitar, too?

Best regards,
Radu

[Taylor]

I finally got around to etching one of these and will be building it soon. I did find some of the traces to be too close and wound up with bridges, but it may just be a lack of sophistication with my etching rig.

[Taylor]

Scratch that, no bridges. I was looking at the board post-etch but before actually wiping the toner off with acetone. The traces looked too close, but in fact they etched perfectly. A nice board layout, looking forward to building this.

[gigimarga]

Has anyone built it for guitar?

[Brymus]

I had forgot about this thread when I started the 7 band graphic EQ on my breadboard.
I almost have it dialed in....
But IMHO this is probably a much better design for some serious tone shaping,again nice work Azlitz.
And thanks for sharing with everyone.

[aziltz]

Sorry guys I'm in the middle of moving with limited Internet axcess. I'll catch up this weekend

[aziltz]

I'm back in town but with limited email access at home.  please feel free to post any build reports or comments as you work through it.  I wish I could have verified it already but I've just been so busy with school.

gigimarga, I don't have any notes on Cap values for guitar unfortunately, however the math is very simple and comes directly from an RG article.  http://geofex.com/article_folders/eqs/paramet.htm

It's in the section around the 3rd schematic from the top.  Basically you fiddle with values until you get the range that you want.  I used an excel file, but I'm not sure where It is at the moment.  I found that a bit of overlap of each one works best.