For the electronics bro... Wee help with a buffer please?

[Pierre]

Like a lot of people I've been messing with the TS/SD1 circuitry for a while and I figured I should do some more messing about to find EXACTLY what I need, maybe a couple of pedals, then house them and do a real custom thing for myself. I'll call it the Hot Baguette since I'm French. Anyway the plan is to have the same 3 controls as a TS, with maybe two wee switches to control two different gain resistors and possible a symmetric/assymetric clipping switch. Either way the pedal will get a flatter EQ, smoother gain and more open sound. The diodes will be 1N4002 and the opamp a TL072. I'll first mod a SD1 or two (thank you Boss!) and then finalize the design in a box with extra switches here and there.

This is not to sell to people: I have very limited knowledge of electronics and this would be my take on a TS circuit by changing components everywhere and checking out what differences it makes.

I'd like to use a DPDT stompswitch as I'd want the pedal to be buffered and have an indicator LED. So I'd switch it in right before the output and the other side of the DPDT will control the LED.

I hope it's ok to link this geofex image..?

The main question is... what buffer should I use, that'd guarantee me no tone sucking, if at all possible..? On the AMZ buffer page there is one that's noted as being used on TS style pedals. I guess that'd be a good choice?

Also for the output buffer... could I just use the SD1's?

Mostly I'm concerned with no tone sucking, the capacity to drive long cables, high input impedance and using parts and trannies easy to find.

I really want to avoid true bypass. Basically I'd like this pedal to perform as a buffer and a clean boost or OD.

Thanks a lot if you can help!

Pierre

 

[PFDarkside]

Re: For the electronics bro... Wee help with a buffer please?

Does the typical opamp buffer work, just put it first in line? Regardless, I don't see why you wouldn't want TB, will this be your ONLY pedal in line? If so, I see why, but if not, put a buffered pedal before and you're golden.

Another option is to build a high in impedance, low out impedance flat response clean boost in front of your gain circuit. Use something like the ZVex SHO circuit, leave it always on as your input stage, then use TB on the gain portion of the circuit. (Maybe use a resistor/pot network in place of the pot so it goes from unity to some boost of your choosing)

Finally if your really set on using a buffer, try the Boss style JFET one, although that will be more of an exercise to see if you can do it than to realize any gains.

 

[Pierre]

Re: For the electronics bro... Wee help with a buffer please?

I want to use this pedal first in line, as a boost or light OD and a buffer I'd have full confidence in basically.

 

[Pierre]

Re: For the electronics bro... Wee help with a buffer please?

Bah I'll just use a buffer before the circuit's input and switch after that using a 3PDT It'll make things easier, guarantee no tone sucking AND I'll have my buffer.

 

[Vasshu the humanoid typhoon]

Re: For the electronics bro... Wee help with a buffer please?

If you use a quadop-amp you can use one of the outlets as buffer.
We do that in the Plexi, HDBs, and so on!
And...death to stinking true bypass
Like a TL-074...I can send some for you if you like
Niels

 

[Pierre]

Re: For the electronics bro... Wee help with a buffer please?

Indeed hahah I'll use a true bypass circuit but have a buffer always on.

The one question remaining is, will the input buffer's output impedance be low enough for when the circuit is bypassed?

 

[Vasshu the humanoid typhoon]

Re: For the electronics bro... Wee help with a buffer please?

Just make it 1mega in and about 200ohm out

 

[Pierre]

Re: For the electronics bro... Wee help with a buffer please?

I'd like to use this buffer basically. So if I have this on constantly in the signal path, how do I know if its output impedance is low enough?

Also, the input impedance seems to be only of about 510K... if I understand this right (there seems to be a lot more maths and such involved but ah well...). Can I just replace that resistor by a 1M and be happy?

Also, why is there a highpass filter before it? I always wondered... wouldn't it be better to let the full frequencies of the pickup through? Or is it there to filter voltage?