Hi there Everyone,
I would like to build up a 10 band graphic equalizer based on the LM833 datasheet from TI. A sample circuit is shown on page 14 along with a table of various component values for the different frequencies. But, they don't provide any formula or equation that I can find showing how those component values are determined.
I've been Googling, Duckducking and Dogpiling for the past several days trying to find some site that explains how the component values are selected. But until now, haven't found a site that explains anything about this.
What I'd like to do is give other frequencies a go (that are not listed in the table of the datasheet) to see how they might sound. For instance 800Hz, 3kHz, 10kHz, 12kHz, etc. I also want to give other op-amps (NE5532, LM4562, OPA2604, NJM2068) a try to compare the resulting sound.
So, would anyone know if there might be some spreadsheet I could download or a website in which I could input the desired frequencies and the various component values would be provided? Or perhaps even a comprehensive table listing multiple frequencies and their corresponding component values?
Thanks All!
Ken
I would like to build up a 10 band graphic equalizer based on the LM833 datasheet from TI. A sample circuit is shown on page 14 along with a table of various component values for the different frequencies. But, they don't provide any formula or equation that I can find showing how those component values are determined.
I've been Googling, Duckducking and Dogpiling for the past several days trying to find some site that explains how the component values are selected. But until now, haven't found a site that explains anything about this.
What I'd like to do is give other frequencies a go (that are not listed in the table of the datasheet) to see how they might sound. For instance 800Hz, 3kHz, 10kHz, 12kHz, etc. I also want to give other op-amps (NE5532, LM4562, OPA2604, NJM2068) a try to compare the resulting sound.
So, would anyone know if there might be some spreadsheet I could download or a website in which I could input the desired frequencies and the various component values would be provided? Or perhaps even a comprehensive table listing multiple frequencies and their corresponding component values?
Thanks All!
Ken
Hi,
Each element is a gyrator consisting of the op-amp C1, R1 and R2
to simulate an inductor, in series with C2 to form a LCR resonant circuit.
An example of a gyrator simulating inductance, with an approximate equivalent circuit below.
The two Zin have similar values in typical applications. Circuit from Berndt & Dutta Roy (1969)
You can work out the frequency from L and C. R controls the Q.
rgds, sreten.
Each element is a gyrator consisting of the op-amp C1, R1 and R2
to simulate an inductor, in series with C2 to form a LCR resonant circuit.
An example of a gyrator simulating inductance, with an approximate equivalent circuit below.
The two Zin have similar values in typical applications. Circuit from Berndt & Dutta Roy (1969)
You can work out the frequency from L and C. R controls the Q.
rgds, sreten.
Last edited:
Hi Olaf,
Thanks for the tip regarding these programs.
I have tried both, but I guess, I'm still not quite understanding the process.
As an example, I used the Filter Pro software and selected the Bandpass Filter Type. I then selected a frequency of 1000Hz, since I wanted to confirm that the end result would match the components shown in the table on the datasheet. Unfortunately, the end result showed a completely different schematic diagram and all component values and placement that were not the least bit similar with those provided in the datasheet.
So, back to my original question. Might there would some kind of formula or program specific to what is shown on that data sheet? Something that would allow me to enter the same frequencies as shown on that datasheet and which would provide the same component values as listed in that table? At least it would give me a starting point to determine other frequencies not shown.
Thanks!
Ken
Thanks for the tip regarding these programs.
I have tried both, but I guess, I'm still not quite understanding the process.
As an example, I used the Filter Pro software and selected the Bandpass Filter Type. I then selected a frequency of 1000Hz, since I wanted to confirm that the end result would match the components shown in the table on the datasheet. Unfortunately, the end result showed a completely different schematic diagram and all component values and placement that were not the least bit similar with those provided in the datasheet.
So, back to my original question. Might there would some kind of formula or program specific to what is shown on that data sheet? Something that would allow me to enter the same frequencies as shown on that datasheet and which would provide the same component values as listed in that table? At least it would give me a starting point to determine other frequencies not shown.
Thanks!
Ken
Hi, you might like to check out this thread http://www.diyaudio.com/forums/analog-line-level/241239-custom-equalizer-design-needed.html
For eg in POST # 9, 100Hz - C1 = 47nf C2 = 470nf
If you half the value of the capacitors, then f = 200Hz
If you double the value of the capacitors, then f = 50Hz
*
Also notice how the choice of OpAmp effects the HF response.
*
You could use the gyrator calculator posted by graygem in POST # 22. Ignore the transistor one, & the 4.5V mention.
For eg in POST # 9, 100Hz - C1 = 47nf C2 = 470nf
If you half the value of the capacitors, then f = 200Hz
If you double the value of the capacitors, then f = 50Hz
*
Also notice how the choice of OpAmp effects the HF response.
*
You could use the gyrator calculator posted by graygem in POST # 22. Ignore the transistor one, & the 4.5V mention.
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