TI's Tone control

[JhonDoe]

hi!

I would like to build the conplete tone control from aplication bulletin of TI (http://focus.ti.com/lit/an/sboa082/sboa082.pdf) for my computer and need some help for getting the values of the pot(the Bass and Treable). What will be the best values for this pot's?

I will connect this tone control in my GC(inverted vertion) the application show's for non-inverted do I need R11(1meg) and R12(22k)?

my plan is to remove the balance pot and the two limitting res. just a volume pot. do u tink 50k will be sufficient for this?

one more thing. the schematics shows in page 1 figure 1 the 2 resistors R6 are 11k whch have the same value but in page 2 figure3 R6 have a different value 11k and 22k. which is correct for the figure?

[JhonDoe]

anyone pls help me in my ignorance in mathematical figures!!????

[JojoD818]

Hi,

I have built that one and based on the app note, I used a 100K linear pot. It sound is worth building, but be smart in choosing your opamps. Read their corresponding datasheets for further references.

HTH,
JojoD

[JojoD818]

I forgot, I used both 11K.

[metal]

Hi

You can use OPA134/2134. or OPA227/2227, OPA228/2228.
As they are intended for audio use.

Kind Day

[BC]

I contacted TI a few months ago about that app. information. If you study the schematic there are errors. If you read the information, there are errors. TI told me that the author no longer works for BB/TI. Your Math isn't necessarily bad. Sorry for negative information.

[metal]

You can download OPA227 Datasheet, you will find another tone control circuit

[Svante]

Interesting to note in that schematic is that if you turn the volume up to max, and the balance max sideways, one input gets shorted. For other volumes, the L-R balance will shift with the volume pot position, unless it is centered.

[JhonDoe]

thanks guys!...

Originally posted by JojoD818
Hi,

I have built that one and based on the app note, I used a 100K linear pot. It sound is worth building, but be smart in choosing your opamps. Read their corresponding datasheets for further references.

HTH,
JojoD

did u mean 100k for both(treble and bass)?

Originally posted by BC
I contacted TI a few months ago about that app. information. If you study the schematic there are errors. If you read the information, there are errors. TI told me that the author no longer works for BB/TI. Your Math isn't necessarily bad. Sorry for negative information.

I thought it was me who have not undestand the figures in that app.


I got another question guys.. in power amp stage I'm running the chip in inverted topology, the app. shows the power amp in non inverted, can i remove the two input res before and after the input cap???

[Tony]

hi,

you may want to try dual 250k linear taper for the bass, and 50k for the treble, also linear taper....

you can not remove the resistor after the input cap to the opa549 amp. it is meant to bias the input on the op amp...the 1meg is high enough and is better to leave it as is....