I need a simple eq

[Krinor]

Hi guys,
I can't find a simple eq project anywhere... I checked out the Tonepad and ROG eq's but they're not quite what I'm after.
What I'd like to build is an eq with three pots to fit in a small mxr sized box without any ic's. Does such a project exist somewhere out there ?

[snoof]

If you want to go active EQ, i'm pretty sure you'll have to go with opamps...

[demonstar]

I'm guessing that you probably can't do that because by the time your passive tone controls are done with the signal, the signal strength will have decreased significantly. So you'd end up with a normal signal in and very weak output signal. There would need to be something in there to boost the signal back up such as an opamp or transistor.

Whats the reason for avoiding ICs?

[Krinor]

He he... Er... Because I haven't got any right now. I've got a bunch of transistors though.

[Ben N]

You could make it like a SS version of a typical preamp, i.e. sandwich a passive TMB tone stack (Fender, Marshall, Vox, Bax/Ampeg) between transistor gain stages (boosters), like Fetzers or Stratoblasters if you have jfets, NPN boosts or LPBs if you have BJTs, or AMZ Boosts if you have mosfets, or some combination thereof. This would probably color your sound more than an opamp based design and give you less eq flexibility, but it may be suited to your needs.

[Dragonfly]

Why don't you just combine a jfet boost, baxandall tone stack, and a jfet buffer ?

[GREEN FUZ]

How about something like this.

http://www.mitedu.freeserve.co.uk/Circuits/Audio/t-ctrl.htm

Basic treble and bass cut/boost based on Baxandall circuit mentioned by Dragonfly. Probably not what you had in mind.

[Ben N]

Bad link?

[bleubleu]

Why no ICs ?

The GGG 6 band equalizer is very nice and fits in a small box if you use slide pots (see the Taiwan Alpha Slide Potentiometers 30mm Linear 5K on mouser). Mine is done, im just waiting for the box to come out of the machine shop to complete it. You could probably modify it to 3-band.

Mr. EQ on runoffgroove.com is a "3 switches" equalizer. But again, it uses ICs...

Opamps only cost a few cents, there really is no reason to NOT use them in my opinion...

Mat

[GREEN FUZ]

Bad link?

Fixed.

[Krinor]

Why no ICs ?

The GGG 6 band equalizer is very nice and fits in a small box if you use slide pots (see the Taiwan Alpha Slide Potentiometers 30mm Linear 5K on mouser). Mine is done, im just waiting for the box to come out of the machine shop to complete it. You could probably modify it to 3-band.

Mr. EQ on runoffgroove.com is a "3 switches" equalizer. But again, it uses ICs...

Opamps only cost a few cents, there really is no reason to NOT use them in my opinion...

Mat

I'm sorry. I realize I have made a fool of myself now.  I guess I'll just have to be more patient and order some IC's. After all money is not an issue. 

Let me refraze my question:

Can someone give me a good link to a simple EQ project which features three or four pots, for instance:
Treble, Mid, Bass
Treble, Bass, Level
Or simply: Tone, Level

What I am after is an extremely basic thing. Something like the Big muff tone control but maybe a little bit more versatile. A simple pedal to give more pressence and to scoop the mids. I don't mind if the circuit colours my sound. But is there really no such thing in ready to build vero layout form or something like that ? Please forgive my utter noobness.  

[Ben N]

OK, GF, there it is. Yeah, that's about right. Although Krinor had initially said he wanted three knobs, so I figured a modified Bax would be in order, like on the second generation Ampegs with the inductor based mid control and shift switch, or the one stm posted here some time back.

Krinor, no need to blush--you posed a perfectly reasonable question. Matt is right that eq circuits are easier to build and may work better with ICs for most purposes, but that doesn't mean there is no other way. If the idea of the BMP tonestack interests you, take a look at the many mods available in the AMZ Lab Notebook, and also at the onboard bass preamp at Albert Kreuzer's website, which is basically two Tillman jfet preamps with a modified BMP stack inbetween. If you have a breadboard, you may hav some fun experimenting with the options, and opamps are not required.

Good luck.

[bleubleu]

The guvnor on tonepad (http://www.tonepad.com/project.asp?id=57) has a 3 band equalizer built in. I wonder if there is a way to remove the distortion and only keep the amplification and equalizing part on the circuit ? It is a very simple circuit, the eq. part seem to be completely passive, just a series of capacitors and stuff. Any thought ?

Mat

[aron]

Check out some of these. Put a JFET booster in front.

http://www.diystompboxes.com/smfforum/index.php?board=21.0

[Dragonfly]

for those interested in a simple 2 band (hi/lo) , Jack recently posted a Big Muff tone stack mod at AMZ...

could be useful to many people.

[aron]

Yeah, I just read that article! I added it to the EQ section.

Thanks!

[Krinor]

Check out some of these. Put a JFET booster in front.

http://www.diystompboxes.com/smfforum/index.php?board=21.0

Aron, thanks for posting that link. Very informative stuff. I wonder why I didn't find that on my own. I guess I'm blind.  

[aron]

Kristian,

Well, like you, I wanted simple EQ circuits too. That's why I've been adding to that section. If you find more, post them.

Thanks!

[Dragonfly]

Yeah, I just read that article! I added it to the EQ section.

Thanks!

I would pop a mosfet boost in front, a bjt buffer at the end, and box it up

hi imp in, a nice versatile eq, and a lo imp out.

[Mark Hammer]

How about something like this.

http://www.mitedu.freeserve.co.uk/Circuits/Audio/t-ctrl.htm

Basic treble and bass cut/boost based on Baxandall circuit mentioned by Dragonfly. Probably not what you had in mind.

This circuit is VERY close to an on-board preamp project that was printed in Guitar Player many years ago.  The designer apparently had been involved with either Rex Bogue (the guy who made John McLaughlin's famous doubleneck)  or had installed stuff in Frank Zappa's guitars, or both.  I built it into a guitar I had for a number of years.  Worked great.  Used 2N5089s for less noise and lotsa gain.

Three basic differences from the one linked to:
1) The GP circuit had variable gain in the form of a trimpot and emitter cap in parallel with the 2k2 resistor in the first stage.
2) The tone control pots were 250k if I'm not mistaken (so you could use what was on the guitar already)
3) The turnover frequencies were chosen to complement the guitar as signal source, where the circuit shown appears to have adopted corner frequencies more suitable to program material (i.e., recorded music).  Easily adaptable, though.