Boss CE-1 Preamp help

[RLawlor]

I've recently taken the schematic of the boss ce-1 and drew up a schematic to isolate the preamp. I have decided to use lm741s as my opamps and have a circuit built to convert 9Vdc to +15Vdc and -15Vdc. When hooked up sound comes through OKAY but when the notes decay it sound as though they're dying off possibly due to lack of current or low voltage? Any help would be great, thanks. (PS I'm using a bufffer in front of the original 50k pot rather than the 500k pot mod for guitar impedance)

[duck_arse]

others might tell you that you can get V+ and V- from a single charge pump IC, but I've never used one so can't comment. on your input transistor, you have 4k7 to ground, which will load your input badly. the 56k that follows might prove a bit low a value as well.

towards the end of your circuit, you seem to have a doubling rectifier instead of a clipping type circuit. perhaps you have picked the wrong section of the original circuit.

[Scruffie]

towards the end of your circuit, you seem to have a doubling rectifier instead of a clipping type circuit. perhaps you have picked the wrong section of the original circuit.

Indeed, that would be the rectifier for the gating J-FET.

The Pre-Amp is just the 1st 741 or Transistor bit... probably not much point in running it at +/- 15V for guitar either, +/-9V from a single charge pump would do.

[RLawlor]

Thanks for the help on this, the one opamp simplifies this a lot.

[fernandosk]

Hi. Did you have any sucess with the pedal? I'm interesting in building this circuit but have seen reports of 7660s charge pumps frying. It would run from +9V and provide -9V in those applications, with a TL071 as the op-amp for the boost circuit.