pretty urgent: need bass-mid-treble schematic help appriociated

Hi All

I am building a guitar amp, and all of a sudden a more or less well known guitar player in Holland is interested in using it. Me and my big mouth have promised him that a prototype would be ready by Monday. I am pretty good on schedule with everything, except for the tone control. I have found a schematic on the internet of a nice guitar tone control, but I need to adapt it for stereo, and in my amp it will be fed by a line level input. I have emailed this guy about it but so far no reply and I am in a bit of a hurry... need to do the sourcing tomorrow.
Can you guys maybe help me out a bit? Would be very much appreciated!

Cheers

Erik

Hi Erik,

The tone control in that circuit is a passive (lossy)  network and does not care about the signal level. The first half of TL072 is also wired as unity gain and provides only the high input impedance.  The gain is only added on the second half. I am not sure what your own circuit is like but you can literally use the whole circuit as is by setting the desired gain. Or just cut out the tone control section between the input jack and the TL072 and insert it within your circuit.

Thank you very much!!!

One thing I do not completely understand about the schematic is the 4,5v connected to the r4.... if I see it correctly there are two powersources in the schematic?

You are welcome.

The opamp is operating on a single rail, so it needs to be biased to half the supply voltage. Divide 9 volt supply using 2 x 10K resistors and wire it to R4/6 node.

if it were a bipolar design, that 4.5v bias rail would become ground...

Thanks a lot guys.. working on it.. will inform you briefly!

You need to decouple the 4.5V point with an small electrolytic to ground - 47uF 10V will do.

Cheers

Ian

if you have any enquires - talk to phil abbot username "phatt" at ssguitar.com - he always seems to hanging out there.
other suggestion - duncan's tone stack calculator - http://www.duncanamps.com/tsc/

Ian and dogbox.. thanks... I talked to Phil as well thanks again!