DIY Equalizer, but really simple

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Hi,

Do any of u have plans for a equalizer one can put in the signal way before the power amp?

I plan to build an amp with an equalizer integrated. I already have a volume control, and I'm pretty sure I can figure out a balance pot, but the bass and treble-control poses more problems.

It needen't be a complicated design, just bass an treble-control would be sufficient, as long as it's easy to build.

I have been looking on this chip http://www.elfa.se/elfa/produkter/se/220740.htm
It is a 7 band equ, but it seems too complicated for my brain 🙂

Best Regards
/Chris
 
Ok, so I'll go with this circuit.
But I still don't understand two things.

1. Does one have to use all the seven bands, or does it work ok if you just hook 2 band upp and leave 5 floating?

2. What is that amplifier circuit in the diagram(arrow)? and do you really need it. I can't find that circuit M5218 anywhere!! Can I use something else maybe or just skip it?
 

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That is an opamp in a unity gain configuration (an input buffer). It is there for stability. I personally wouldn't leave it out, but the Opamp (M5218) could be substituted for a better sounding one (such as an Analogue Devices / Burr Brown item)

Edit:
I do not believe you could leave the bands floating as they seem to be set frequencies. The bands are far too narrow for just bass/treble. You could leave the central 5 set at 'zero' but I'm not sure it'd sound as you might expect!

Hope this helps,
Gaz
 
Hi,

Thanks for the great answers!! I'll do as you say and use resistors as substitute for the the pots.

Now there's only one thing in this schematic that is troubling me, the op-amp. I can't get that specific component, but if you'd know about some other op-amp, preferbly from this list :

http://www.elfa.se/elfa-bin/lt.pl?sort=&pics=&1860017&1860019&1860063

it would be great cause then I could get started building!🙂)
Or, the very simplest thing for me to do would be to entirely leave it out, even though the results probably wouldn't be that great🙁

Best Regards,
Chris
 
You can infact use not all seven bands. Each band consist only of a emitter follower and I don't see why you only just exlude 5 of the bands but then I think make a traditional tone control is better (sounding).

LF356 is an ancient opamp, works though but somewhat noisy.

If you deside to make a traditional tone control, use an OPA134 OPA2134.
 
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