Texas Instruments inspired 10 band eq

[Evz]

Hello!

I had some time and decided to look over one of the articles TI puts out in the audio section... check it out HERE it is a nice article illustrating a schematic of a 10 band eq, i went ahead and drew it up in eagle,can you please look over the article and let me know if this 10 band eq will work? i plan on using 18v to power all opamps ( i heard its better to help when eq'ing the lower frequencies) and since this is a published article i would guess it should work... i have made a layout for it but it is inteneded for small capacitors IE tantulams for the 6.4uF and ceramic for anything less have 100n... any insight on this design?

For the vcc/2  i used a simple splitter like on the ts9... probably missing a coupling cap on the 9v tho...

Please send any insight/suggesions/comments possible! looking to try and get this proto'ed!

Schematic drawn up can be found HERE

[JKowalski]

If TI published it, I'm pretty sure it's gonna work perfectly fine 

Sounds like you need a breadboard!

[zyxwyvu]

I'm fairly certain that the potentiometers should be in parallel, not series, as in this schematic: http://www.geofex.com/FX_images/eh7600.gif. The TI article you linked is ambiguous in this aspect from what I saw, but I've only ever seen the configuration in the schematic I linked.

[Evz]

i was just wondering, what would be the difference of grounding on the positive terminal of the IC instead of feeding 9v to it? (as in in the TI schematic vs the linked schem by zyxwyvu)

[zyxwyvu]

i was just wondering, what would be the difference of grounding on the positive terminal of the IC instead of feeding 9v to it? (as in in the TI schematic vs the linked schem by zyxwyvu)

Which IC are you referring to?

[Evz]

i mean in the 'inductor' stages; there isa resistor from the positive pin to the ground on the ehx schem, but the TI schem has the resistor (100k) connected to the vcc/2

[zyxwyvu]

i mean in the 'inductor' stages; there isa resistor from the positive pin to the ground on the ehx schem, but the TI schem has the resistor (100k) connected to the vcc/2

The resistor should be connected to the middle of the supply voltages. The schematic I linked is a split-supply design (+12,0,-12), so it is connected to ground. The TI design is single supply (vcc,0), so it is connected to vcc/2.

[Transmogrifox]

I'm fairly certain that the potentiometers should be in parallel, not series, as in this schematic: http://www.geofex.com/FX_images/eh7600.gif. The TI article you linked is ambiguous in this aspect from what I saw, but I've only ever seen the configuration in the schematic I linked.

This is correct.  In fact, the schematic linked here is a good EQ to build if that's what you're after.  These will end up being about the same thing in the end.

[Evz]

Would it be possible to get a split voltage with a 24v bipolar split design? i would guess it is abit odd to send 24v just to split it to +12, 0, -12 instead of using a transformer, but in the case of the trasnformer, which kind would i need? 120-0-12? (i am nood when it comes to transformers...)

the bipolar idea coms from here... http://www.generalguitargadgets.com/richardo/distortion/index.html i believe warren young ( i believe that's his name) has an article found here - http://tangentsoft.net/elec/vgrounds.html

any comments on that?

[Transmogrifox]

It's as easy to do that with 24V as it is with 9V.  For an EQ like this, there is little current to/from ground that isn't AC, so the simple resistor + capacitor divider is a fine bet. 

When talking about a virtual ground from a single-sided supply, we're just playing word games by talking about +/-12V versus 0,12V,24V.  That all depends where you connect the ground reference in your circuit.

All that really matters is that the DC bias point on the op amp keeps all pins at a voltage that is further from either rail than the anticipated voltage swing.  A 24V supply split 50/50 does this nicely for an EQ circuit.