This isn’t as advanced as what you’re suggesting. Same people that make the pedal the Transcendence is based on.
Thanks for the link, I wasn't aware of this product.
There's no buffer that I'd call advanced. It's a basic circuit block. The devil is in the details. You simply
cannot get the full benefits of an onboard buffer unless you
eliminate the standard high value volume pot between the pickups and the buffer, which is a significant source of hiss when backed up. In this situation, it greatly adds to the pickup's output impedance, ruining your noise floor. The Redeemer does not replace the volume, it comes after it (I checked their wiring diagrams). There goes the biggest advantage to having it onboard. You might as well put it in a pedal or belt pack with a short cable from the guitar, and it would work in just the same non-ideal way.
Also, it draws 3mA (for reference, mine's at 0.22mA), which is quite thirsty IMO for an onboard buffer. Their math is questionable, too. At 3mA, a 9V battery (~450mAh) would last about 150 hours, not the 300 they say. Moreover, the noise floor they quote (-125dBu)
cannot physically happen except when the volume pot is fully cut, at which point a passive guitar would be even quieter (dead short on output, zero noise!).
Allow me to do some calculations. The pickups themselves, with the volume up, have
at least 5kOhm of resistance (it gets
a lot higher with the volume backed off), which sets the lowest theoretical noise floor out of the guitar to about -116 dBu, even if your buffer were an ideal "wire with gain". A 500k volume pot at 50% adds 250k of series resistance to the pickups, which bumps the noise floor to no less than -99dBu (17 dBs more, or 7
times the full-volume noise!). Add 60dB of small signal gain from a compressor + distortion, and your noise floor is now up at -
39dBu. That's some
forking loud hiss.
My buffer removes the 250k or 500k volume pot and replaces it with a 5k,
post-buffer volume. At 50%, that pot is a 2.5k resistance to the output. That's worth, by itself, about -119dBu of noise over a 20kHz bandwidth. Add to that
half of the combined noise (remember, the pot is at 50%) of the 5k pickups (-116dBu) + my buffer's self noise (-118dBu, the equivalent of a single 3k resistor). Comes down to about -116dBu, real life noise floor, with volume at 50% (uncorrelated noise adds in funny ways). Now, add the same 60dB of gain from i.e. a compressor + distortion, and you're up to -
56dBu. HUGE difference from the -39dBu above. Like turning on Dolby C on a cassete player, if you've experienced that. You can now easily skip the noise gate.
Same guitar, same 50% volume setting, different buffers.
Apart from that, I commend the Redeemer's makers for the generally correct, no-nonsense explanations of how it works and why you'd want one. Too many makers spread bullshit in any number of audio subfields.
/endrant
Having said all this, I don't think I'll make this into a product, as it makes very little business sense. For starters, just the pot I want to use costs me about C$15 in small quantities (Bourns 91 series), and the op amp about C$4... And I won't make anything any less than the best that I know how to make, so I won't use any lesser parts.
