Someone help me understand how this circuit works please

[angelothewolf]

It is a 3-band equalizer circuit, with sweepable mid ranging from 350 hz to 5 khz. the low cut is fixed at 100hz

So the idea is to add a switch to change the bass freq, from 100hz to 80hz or something like that.
Im requesting a little help to mod this Eq, im not quite understanding the circuit. Are that 2 33nf caps responsible for the low freq cut?

thanks      

[angelothewolf]

actualy its a vintage YAMAHA 2408M, if someone want to know.
btw im replacing this jrc4558 with OP275 and recaping too!

[Jay_Diddy_B]

Hi,

The Hi and Low controls resembles the famous Baxandall circuit.

See this link: http://headwize.com/?page_id=741


The circuit has been modified to add the MID control.

Jay_Diddy_B

[angelothewolf]

ohhh!  god bless you 

[w2aew]

Hi,

The Hi and Low controls resembles the famous Baxandall circuit.

See this link: http://headwize.com/?page_id=741


The circuit has been modified to add the MID control.

Jay_Diddy_B

It's also the same basic bass/treble control circuit (without the midrange addition) that I used in my little microphone preamp/eq that I built for use with an old crystal mic and my ham radio.  See this video for a little demo on how the circuit works:

[angelothewolf]

Ok thanks everyone for the answers! now i know what a baxandall circuit is!
So i put a dpdt switch to change the two 33n caps to 100n, now i got two options for the low freq control of this console