Lets design an EQ

[col]

OK I don't want to offend anyone but if we design something between us surely it can't belong to anyone. I saw an MN3607 in the Rapid catalogue which seemed ideal for a DIY eq. Unfortunately it was witdrawn but I eventually managed to get one. This is my fitrst stab at it;
http://s159.photobucket.com/albums/t159/col07768/?action=view&current=eq.jpg
I didn't do a schematic as that's available on the datasheet. I also noticed that the cap values given for a typical usage were not commonly available if at all. The formulae were however available so I created a spreadsheet, used the values from my Behringer EQ for the centre frequencies and worked out the cap values based on this. I then chose the nearest easily available values and fed them back into the spreadsheet to check that they wern't too far away from the desired values. Once I'd reached a point hat I was happy with I proceeded to build it. I also put a standard op-amp circuit in front as shown on the datasheet.
Values chosen were;
C1 220n, C2 470n, C3 4n7, C4 220n, C5 10n, C6 150n, C7 6n8, C8 47n, C9 2n2, C10 22n, C11 820p,
C12 10n, C13 270p, C14 4n7, C15 3u3, C16 470p, C17 3u3, C18 47u, C19 22u, C20 22u, C22 1u,C23 100p.
R1 8K2, R2 10K, R3 8K2, R4 47K, R5 47K, R6 100k, R7 100k. Other values are as shown. I also reduced the 1meg pot shown to 470k.
The centre frequencies chosen were 15000, 6000, 2500, 1000, 400, 150 and 60.
The first thing I noticed was that the pre amp was uneccesary. It drove the MN3607 into distortion at anything above zero. I intend modifying this part to after the EQ. The MN3607 seems to have unity gain by probing around so the amplifier is unnecessary but it's useful to have. The second thing was that the frequencies were not altered equally. While I had massive control over some there was very poor control over others. I don't think the maths is at fault and I can't see any bridges.
Please feel free to amend, change, alter, improve or do what you will with this circuit but please post your findings if you do. The data for the chip is easily available on the internet and they are quite low in cost.

[A.S.P.]

LA3607 ?

[col]

You know you're right! Sorry I'd been doing something else just before I did this. Thanks for pointing it out.