(Japanese?) Parametric EQ PCB, layout, build report

[Morocotopo]

Hi people, Here´s a parametric EQ I made, since I´m about to box it, I thought to share my work. The schem is from some site that has lots of scans from an FX book in ¿japanese?, I don´t remember now exactly wich one. It´s a nice little circuit, works well, easy to make, not complicated. I cleaned and slightly modified the original PCB, added R21, the notes in green are my mods/thoughts. The technical specs are in the schem.
Original file:

[Morocotopo]

PCB and Layout:

[Morocotopo]

Schem:

[Morocotopo]

My build:


Hope it´s of use to someone. I hope the files are clear, if not, tell me and I can ¿mail ? ¿PM? you better quality ones. Especially the PCB, I don´t know if JPG files are good for etching in terms of resolution, etc. I believe the PCB is to be printed at 100%, but try in a plain paper first to be sure.
By the way, could some expert tell how to change the freq spectrum this EQ covers (eg. to shift it up or down, or extend it). I think it´s a matter of changing some components values, but I don´t know wich ones.

Morocotopo

[Morocotopo]

I forgot, there´s a couple of holes in the original PCB that serve no function, I left them just in case...

Morocotopo

[Wild Zebra]

Looks good!  thanks.

[Aharon]

Thanks for sharing Morocotopo.
Aharon

[Morocotopo]

Thanks for the thanks ( ). Now, maybe some of the "perf-vero-or-whatever-you-call-the-boards-with-holes" geniuses will asume the challenge of making a layout for the benefit of those who don´t etch, based in the PCB? Shouldn´t be so difficult...
I dare you!! 

Morocotopo

[John Lyons]

COol! Thanks for posting all the stuff.
What are your thoughts on the sound of the circuit. Sounds like you like it I was just wondering if you would go into some detail.
I'm familiar with Paramentric eqs...
Thanks

John

[$uperpuma]

I just happen to have about 4 074's just lying around... I may have to try this one!

[markm]

I just happen to have about 4 074's just lying around... I may have to try this one!

Same here! 

[Morocotopo]

 Basicaudio, I like this very much. I previously built the Geofex param EQ, but didn´t like the fact that it only reaches to 2 KHz (yes, I know you can mod the freq spectrum of that circuit, but the math proved to be too much for my little brain cells ). So, this one has a more extended freq spectrum. The advantage of the Geofex one is that it has two control sections, so it´s easier to "find" a specific frequency with the freq pot. I guess you could add a "fine" pot to this one, or use a multi turn one, to make exact freq finding easier. But, it works fine as it is. It behaves well, if that makes any sense. I also think that it has more cut/boost capability (in dB) than the Geofex one. Of course, param EQ´s are totally dependent on the settings as to how they sound, and they take some learning to get the most use from.
I wish that it covered the whole audible spectrum (20 to 20KHz), because I plan to use it with a pickup equipped acoustic, for feedback control or tonal shaping, but, since I don´t have such an instrument yet, it´s kind of a "build in advance"  . But, with electric through amp, it´s a very versatile tool, for clean sound shaping or, before an OD pedal, for driving the mids/bass/treble crazy. It feels different than my Boss 6 band EQ, I believe because of the resonance this type of circuits provide, specially with the Q control set for a narrow band. The last two K (approx 5 to 7 KHz) are not of much use with an electric amp because electric gtr speakers usually don´t reach that high.
To sum it up, I´m happy I built this one.
Hope my experiences help you.

Morocotopo

[John Lyons]

Morocotopo
Thanks for the details. sounds good.
I think you will be fine with this for acoustic guitar amplified. 20 to khz is pretty wide range to go for. Acoustic guitar or at least the amplified acoustic will be well within the coverage of this parametric eq.

John

[alfafalfa]

That's a great design Morocotopo , I appreciate this very much especially the pcb.
I 'm absolutely going to build this one.
I think you could also run it with a symetric powersupply for more headroom.
Say + 15 and - 15 volts. This would certainly benefit the transients from a acoustic guitar.
My preamp has the same sort of powersupply you see.
And I may try some Burr Browns for an even cleaner  signal.

Regards

[Morocotopo]

alfalfa, I must say that it´s not my design, I just cleaned the PCB for etching.
How about feeding it with 18V (two batts or a charge pump)? Do you think it would work to give more headroom?
What is a Burr Brown? Some tasty chocolate? 
I don´t think i can get those here, but I can get TLC2272´s. Might try those, I believe they have more headroom than 072/074 IC´s.

[alfafalfa]

"Burr brown" sounds like some very tasty kind of chocolate but it's a very good opamp with low distortion .
Google "burr brown"and you'll find lots of info.
18 volts will certainly give you more headroom but 15 plus and minus will give nearly 30 volts of headroom.
Electronic circuits are as good as their powersupply.

Alf

[xandaum]

This project works, really?
Anyone else get it?