Tonemender Design Question

[Derringer]

http://www.runoffgroove.com/tonemender.html

the tonemender has an input buffer, then the tonestack, then a gain stage.

Is there any reason to not put the gain stage first, then the tonestack, then an output buffer?

When thinking about how amplifiers are designed, the gain usually comes first, then the tonestack, and then maybe additional gain stages or a buffer to the power amp. I'm sure this isn't so with ALL amplifiers ... but I think it's safe to say it's true for the vast majority.

Would having the gain stage before the tonestack maybe "drive" the tonestack more accurately like a guitar amplifier?

[jacobyjd]

Um...I'm pretty sure that gain stage is there to take care of the volume loss from the tone stack...

[Derringer]

I understand that ... but why not have the gain before the TS?  ... by increasing gain there, you're invariably increasing the gain at the output.

so instead of a "gain recovery stage" post tonestack, it would be a "gain boosting" stage pre tonestack.


The question comes up because I built a bax tonestack using a tl072 and I built it with the gain first, then the BAX, then an output buffer. I originally wanted to use it/thought it would be best applied first in my signal chain (to beef up my strat's sound) but it seems to work best at the end of my signal chain ... post distortion/fuzz. And it sounds good. It lets me add lots of "beef" to the single coil tone.

[jacobyjd]

All else equal, it shouldn't make a difference. There may be something in the circuit that I'm not seeing though--perhaps the gain stage also acts as an output buffer?

[earthtonesaudio]

The Tonemender's gain stage and output stage are both also effective buffers for the signal, so switching the order wouldn't make any difference...

UNLESS:

...you have enough gain in the gain stage to cause clipping in either op-amp.  This will add new harmonic content, and so the order will matter more.
...or you drive it with a large signal.  A unity-gain follower will clip later, and in a different way, compared to a non-inverting gain stage.

To my eyes it appears they placed the gain stage last because the signal coming out of the tone stack is reduced in volume, and less likely to clip the post-amplifier.

[Derringer]

UNLESS:

...you have enough gain in the gain stage to cause clipping in either op-amp.  This will add new harmonic content, and so the order will matter more.
...or you drive it with a large signal.  A unity-gain follower will clip later, and in a different way, compared to a non-inverting gain stage.

To my eyes it appears they placed the gain stage last because the signal coming out of the tone stack is reduced in volume, and less likely to clip the post-amplifier.

cool ... that makes good sense

And yeah Jacobyjd, the way I understand it, opamp outputs are ridiculously low impedance (some can drive 600 ohm loads) ... so even a gain stage acts as a quasi-buffer