Graphic EQ Build

[served]

Hi.

I have always dreamed about a Graphic EQ. But newer got a chance to buy one, a money issue or what ever.
Now that the time is hopefully right, I would like to build one.

First I thought I will order the parts and build it from scratch, but then It came clear to me, its is actually cheaper to buy Boss EQ or something like it, than building it.
As I did not want a turnknobs for EQ I pretty much gave up on the idea of building one.

But now here is the idea.

I stumbled on an EQ which is meant for car audio system. Its Pretty decent quality and it has LEDs under the sliders and 7 bands and so on, so its pretty fancy and I like the idea of building a Guitar EQ out of it. 1 problem though, its partially plastic and its not a stompbox, but for home use, it should suit. And I got it for like 5 dollars (3,1 Eur).

Now the main Question is, can I actually use it?
Its slider resistors are 15k, so I cant tear it apart and use the concept of 7 band EQ that was discussed on the forum.

I will upload some pictures and I will try it out and will let you know how does it work as it is.
I have to connect it before amps preamp. Well see.

It would be a cool movement if people would take interest in such thing, old devices are thrown away constantly, but why, if we could use them.

UPDATE: Now I connected it and its Awesome. Just what I needed. Although the band frequenzies are not exactly what they should be, but its good.
So I bassicali got a EQ for 5 bucks and added 4 lugs. I power it from Computer powersupply (12V) that I moded for testing different things.
Its a well spent money!

[Mark Hammer]

You are confusing a graphic with a parametric EQ.

Graphics use sliders so that a "picture" of the equalization across the spectrum can be provided, merely by the settings of the sliders.  The working assumption of graphics is that the designer has no idea where the signal may need emphasis or de-emphasis, so a lot of bands are provided, in much the same way people buy lottery tickets: one of them may be "lucky".

Parametrics use fewer bands (I've never seen more than 4 on a unit), but the individual bands are tunable for where they are, and how broad a range of coverage they have from that point (Q).

While there are a few ^parametric stompboxes, the only one I am familiar with that goes past a single band is that produced by a local company here: Empress.

The Boss pedal you refer to is a graphic equalizer.

[served]

Thank you Mark and you are right its Graphic.

I apologise and I fixed the firs post.


I tried the Eq with Boss Me-50 and Dr Boogie and it really rocks! I could not imagine it woult actually work as good as it does.

[Brymus]

If you can find the caps that work on the 10K band you could change them and get it lower to say maybe 5-6K ,it looks like it uses opamps the GGG graphic EQ and GEO are good places to look for info on changing the center frequency.
Otherwise that looks pretty good for guitar use  (band centers wise) ,nice find and nice implementation 
You could box it up in a bigger enclosure to include the in/out jacks and PS just stick the EQ in the front and mount it normaly like it would in a car.
Does it add any hiss or other color to the signal ?

[served]

I tested it for noise. Nothing, clear as glass. Only thing that makes noise is the fan of the powersupply. It worked pretty loud and actually this thing still amazes me, how was it possible to find this kind of good thing.
I was thinking to box it face up. But I have to find a way to cut aluminium so the sliders could operate as they should. Well see. First I will add lugs to the enclosure and buy a separate powersupply for it.

[RacoonChrist]

Hey did anything ever come of your build?

[iainpunk]

only Mark Hammer is still active on the forum, the others haven't logged since 2015/2016, doubt youll get answer TBH
graphic eq's are not something i recommend fully DIY-ing, but a project like this one where you take an existing graphic EQ and turn that unit in to a stompbox is quite an easy project.
this forum would probably provide enough guidance if needed.

cheers, Iain

[mozz]

 I think it would be easier to put a send and return on your amp, buy a used 31 band rack mount and use that. I never look at the dates on these old threads!