7 Band EQ

[Stevel]

Hi y’all, long time lurker first time poster.

I recently came across (snigger) these ICs from China,
5 PCS LA3607 3607 7-Band Graphic Equalizer @ £1.88.
Used the datasheet to make my first proper vero, seems to work ok,
if anyone is interested or has any tips for the layout please let me know.




I used this site to calculate the Frequencies http://www.muzique.com/lab/gyrator.htm
R1 – 68000 (68K) & R2 – 1200 (1K2) as per datasheet.

I’ll attach the DIYLC v2 file & Datasheet

Apologies to IvIark for the standing resistor (lol).

7-Band_EQ_-_DIYLC_v2.diyLA3607.pdf

[Alex]

Great job Stevel!
With an extra link and a few cuts you could avoid the standing resistor and make it 21 x 12 by cutting the first 2 rows on top.
Something like this:

[Stevel]

That's better, thank you Alex, don't know how you have the patience for the larger boards, took me long enough with this small circuit but very satisfying when it works.

Cheers
Steve

[strassercaster]

nice job guys. how a out a video? so would it be fair to say these cap ranges are pretty much universal for most eq setups?

[Stevel]

Thanks for the interest strassercaster, no video I'm afraid, not equipped for that at the moment.

I based this on the frequencies shown on a BOSS GE-7 with Q around 1.5,  however I have since found the correct Fs & Qs (thanks Mark, 4th May 2014).


 C2           C1           F         Q
390n       82n   98.52 3.45
220n        39n  190.21 3.17
100n       22n  375.63 3.53
47n          10n    812.69 3.47
22n          5n6   1587.34 3.80
10n       2n7 3390.73 3.91
5n6         1n4 6292.41 3.76

I also created an Excel Sheet for the calcs, (the one Mark posted seems to have disappeared).
EQ_Frequency_&_Q_Calculator.xls

There are also 5-Band chips around and all can be joined together for more. The original post showed my first attempt, I have since changed the values and tried values for the Mesa 5-Band (all in the attached Excel).

Cheers
Steve

[Stevel]

They were lined up, try again.

 C2      C1         F         Q
390n   82n      98.52   3.45
220n   39n    190.21   3.17
100n   22n    375.63   3.53
47n    10n     812.69   3.47
22n    5n6   1587.34   3.80
10n    2n7   3390.73   3.91
5n6    1n4   6292.41   3.76

[cylens]

that's really interesting, thank you!

it's +/- 12 dB per band, if I got it right. might be interesting to "double the bands" and make a 3 band +/-24 dB...

[Stevel]

Yes according to the datasheet it's +/- 12 dB per band, don't know if you can double the cut and boost, but you can connect several ics for more individual bands.

[Mark SL]

Has anyone actually built this with good results?

[Stevel]

I built one with the values I originally posted but I think the bands (Q) are a little narrow, required quite a twist of the pots for any effect.

Tried a 5 Band with the Mesa values and that worked rather well, I haven't tried the updated Boss values yet (Q 3.5 - 4.0)

Download the EQ_Frequency_&_Q_Calculator.xls I uploaded and have a play, it's a Gyrator in a chip or try something like this http://tagboardeffects.blogspot.co.uk/2014/05/4-band-gyrator-eq.html

Hope this helps.