Buffer + Booster

[Renegadrian]

Folks, I recently built the clean boost I found at http://www.jer00n.nl/ this one I mean


It's very similar to the average IC buffer like ggg


So my question...How would I use a 072 to have a buffer (always on) and a switchable clean booster?!
thx for your entries!!!

[bool]

Just change the R2 in the first schematic to a pot (some 100k - 250k, whatever works with your signal source), and put a switch in parallel so you will have a unity gain (buffer) when switch is closed, and a booster when switch is open.

Also, you can leave the 10k pot in-circuit, as it is now, or you can simply replace it with an ordinary resistor to act as a pull-down.

IOW, you will want to use a TL071, but if you have a 072, you can make a "twin" version or whatever comes to your mind.

[ayayay!]

Like this?

[Renegadrian]

Yeah I was thinking double op amps as I intended signal going thru buffer and then switchable booster...
so maybe this would work (switch would be the regular foot DPDT) starting with the original schem, only thing is that the volume would be always on...

[Renegadrian]

Jono explain better your schem please

edit - I mean is that a clean booster?! I tried the one I posted and it's quite clean...is yours clean too!?

[Renegadrian]

I also found this topic

that seems quite similar...

[ashcat_lt]

The OP scheme has a set gain booster followed by an attenuator.  The knob will take it from +10db (not a whole lot of boost) down to negative infinity (silence).  If you leave it as is and just add the switch to short across the feedback resistor (it only takes an SPDT) the attenuator will continue to function.  When in buffer mode, it will go from unity gain down to silence.  Unless you always run the booster pegged, then when you switch it off you'll be running below unity.  This would be unacceptable for me.

The schemes with the pot in the feedback loop work better in that aspect.  In boost mode, they will go up from unity to whatever the max gain is.  I haven't done the math to be sure that max gain in any of what you've posted matches your first one, but...

The circuit's "cleanness" depends on the fact that there just isn't a whole lot of gain happening.  All of what you've posted will be clean up to the point where the input signal times the gain asks the opamp to give more voltage than it can.

[ayayay!]

Jono explain better your schem please

edit - I mean is that a clean booster?! I tried the one I posted and it's quite clean...is yours clean too!?

Honestly I have no idea.  I just found it, hoping that may be what you're looking for.  Looks cool though.   

[therecordingart]

I also found this topic

that seems quite similar...

I may be wrong, but with that 250k pot at one extreme you have a gain of 5.32 and at the other extreme you have unity which makes the switch redundant. I've been working on different buffer/stutter designs for a few months and have been playing with adding gain so this is thread is right up my alley.

EDIT: Nevermind. I didn't think that you may want to switch between unity and the boosted signal.

[roseblood11]

I use a very similar pedal:

It's based on the MXR CAE MC-401 booster, but with some improvements:
- added S1 to switch from boost to buffer (if you don't need true bypass, omit the bypass footswitch, hardwire the input an dthe output and maybe use a footswitch for S1...)
- added voltage doubler
- used the second half of the LF442 to provide Vref
- added R.G. Keens millenium 2 bypass switching with input signal shunt to ground

[Minion]

Folks, I recently built the clean boost I found at http://www.jer00n.nl/ this one I mean


It's very similar to the average IC buffer like ggg


So my question...How would I use a 072 to have a buffer (always on) and a switchable clean booster?!
thx for your entries!!!

That curcuit is allmost exactly the same as my onboard pre ......






Just a few of the values are different but you can use the PCB and just change the values ...

[earthtonesaudio]

Jono explain better your schem please

edit - I mean is that a clean booster?! I tried the one I posted and it's quite clean...is yours clean too!?

Honestly I have no idea.  I just found it, hoping that may be what you're looking for.  Looks cool though.   

Hey, I drew that!   
It's a clean booster, as long as you don't overdrive it.  The maximum gain is 11, so if you use a rail-rail op-amp and a 9V supply it can take signals up to about 0.8V p-p without clipping.  It's possible to make a signal that big if you really wail on a passive guitar, but then again that's the maximum gain.  You can decrease the gain by the pot down to about unity, or simply use the switch.  At any setting it acts as a buffer (low output impedance, high input impedance).