Adding a final gain stage to Pauper?

[MattG]

My Pauper (Prince of Tone) suffers the same issue as a Bluesbreaker mk1 clone I built many years ago. That is, the volume needs to be up well past noon (around 2:00-3:00) to be at unity. This isn’t a real problem, given how I use the pedal, it’s just something I’m neurotic about - I like my unity gain around 10:00-noon.

I don’t think I’m the only one with this feeling, as the Pot & Kettle (Snouse Black Box) adds a 2n5457 final gain stage, to solve exactly this problem (with the BB mk1).

The Pro-10 is another BB derivative, it uses a single opamp to bump the output.

And I don’t have an example handy, but I’m sure there are plenty of designs (maybe not necessarily BB based) that use a BJT to boost final level (and lower output impedance).

So there’s no shortage of ways to do this, I’m just asking a more general question: what are the considerations for using one method over the other?

Thanks!

 

[manfesto]

No real thoughts on the matter (I mean, beyond the obvious thought that an op-amp boost is gonna cost more than a transistor boost, but depending on how it’s tuned should have a more linear response), just wanted to toss out a few more examples:

The Glory Hole (Morning Glory) circuit went the JFET-boost-at-the-end route, and if I’m not mistaken it was the first to do so?

The Parthenon (Pantheon) went the op-amp-boost-at-the-end route and is my favorite BB circuit ever.

 

[HamishR]

I have built a BB style pedal with both the single op-amp style last gain stage and the transistor style. I prefer the single op-amp because it ends up using fewer parts.

I have my own BB derived pedal and tried it with both styles, based on the Protein Blue and the Glory Hole. I could get them to sound virtually identical but the op-amp style is faster to build.

 

[MattG]

After doing a bit more research, I found a great example of a BJT gain recovery stage: the Big Muff. That gain stage is the same topology as the LPB-1.

I also ran across the GuitarPCB Afterblaster. This is a JFET boost with a trimmer.

Both @manfesto and the Afterburner mentioned the Glory Hole/Morning Glory, so I had a look at the schematic: Glory Hole or Aion's Cerulean v1. The JFET recovery stage is exactly the same as the Pot & Kettle (Snouse).

Another suggestion I found, courtesy @Chuck D. Bones (sorry, I lost the thread): not a true level booster, but might be enough to calm my neurosis, is to use a linear taper (100kB) pot for volume instead of the default logarithmic (100kA).