MrDEB

changing directions on this EQ unit.
Found this circuit but some of the resistor values are not determined?
http://www.eetkorea.com/ARTICLES/200...URCES=DOWNLOAD
R5, R10, R11
takes 1/2 the number of caps than the circuit I have been using.
UaShem.com | 10 Band Audio Equalizer (print version)
planning on usingTL074 chips, adding 2- 5x10 matrix displays using smd leds
any insight as to resistor values?

RadioRon

R5 is not a critical value. It determines the input impedance looking into the EQU input and might be conveniently set to 10K ohms. You can use any value in the range of 1K to 100K.

R10 is ten times the value of R9 according to the text. That seems awfully high to me and I'm not sure why they do that as it appears this resistor is simply the input R for the mixer (depending on the value of R12 which I don't quite understand).

The final stage is a simple audio summer (audio mixer) whose gain is set by the value of R11. I don't know how much level you want, but a good starting point might be to set it to equal the value of R10.

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RadioRon

audioguru

The EQ circuit designed for 5 filters will need to have the Q increased somehow if you use 10 filters.

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Uncle $crooge

MrDEB

have suggested resistors but R 12??

Attached Images

resistors.GIF (47.7 KB, 10 views)

audioguru

You need to find the formulas for that filter circuit if you want to determine the missing values and to increase the Q so that 10 filters instead of 5 filters can be used.

The "Audio Out" in your schematic is the output of a single bandpass filter. All Audio Outs must be added in a mixer opamp which is the total audio output..

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Uncle $crooge

MrDEB

went online with ON semiconductor and emailed their Tech dept. about resistor values as the application notes state that they have assembled the circuit in question.
Will let you know about the questionable resistor values being so high.