tubedude said:
I emailed them and asked about it, I think they are being a little bit quiet about what it actually is because they are waiting for a patent. I do know that because the output resistance was so low that you could plug the thing directly into a converter and get enough level to record it
OK there is no reason a FET (couple hundred ohms output impedance) cannot drive a converter, which should be 10K ohms input impedance. A guitar signal can be ~0.2V or so, a little shy for a -10dBV converter, but close enough.
A buffer is either going to use FETs which color the sound
FETs are generally regarded as desired for guitar and audio in general due to their tube-like nonlinearities . . .
All that added circuitry compromises the noise floor and signal purity.
OK, what is the noise floor of the average guitar pickup's interference signal? We are talking about a noisy device plugged into an even noisier device--a guitar amp!
The Redeemer is not based on FETs or Op-Amps
OK, a buffer circuit must be a current amplifier. Bottom line, no if ands or buts--somewhere in this thing there is either an electron tube or a semiconductor, which only come in a limited number of flavors--bipolar junction transistor, FET and various flavors thereof, optotransistors, and the latest and greatest oh how I can't WAIT for commercial products--the light-emitting transistor

Maybe I left something out, but my point is, it's somewhere in the Digikey or Mouser catalog, no?
Which one is it?
– It doesn’t color the sound, eat batteries or add noise - the current production Redeemers are Flat within a few hundredth of a dB from 10HZ to 50KHz. The distortion is less than 0.0002% which is about 10 times better than a typical op-amp and a couple of hundred times better than a FET buffer. The noise floor is difficult to measure because it is lower than the test equipment we have available but with the help of Dale Manquen it was calculated to be about -145dBu.
Good for them, they have designed a tremendously good buffer circuit. That much I believe. Again, what is the point when applied to a notoriously noisy circuit, to a signal that is probably going to be subjected to hideous % (20, 30, you pick a number) of THD further down the chain?
They draw less than 2.5mA so a new 9V battery will last for about 300 hours (long life means you can just change the battery when you change the strings).
So? A 2.5mA draw is not particularly low.
The typical FET buffer has an input impedance of a 2 to 4 Megs, and an output impedance of several hundred or a couple of K ohms. The current Redeemer is about 20M on the input and less than 35 ohms on the output. All that means is that the pick-ups are completely unloaded and the output can drive anything – even directly into a mic or line input on a mixer or computer. Kind of like having a direct box straight from the guitar jack.
Few mics are 35 ohm output impedance, and they are just fine into 1K ohm input impedance. Why the hell do they need a 20M ohm input impedance when the freakin' volume pot is 250K ohm? Hence, the pickups are never "completely unloaded".
Look, I never said a buffer amp at the guitar plug isn't a good idea. It is a very good idea (save for Light's tube amp objection). In fact, it's so good that there is already a patent and a page devoted to DIY. This was over 10 years ago.
It could very well be that this device has higher performance specs than those DIY projects. So what? Again, consider the application. An electric guitar doesn't NEED those specs.
If this circuit is so great, it ought to be applied to condenser mics, where it actually could do some good . . .
Disclosure: I am somewhat biased in that while I don't have such a product, nor a plan to offer one (even bogus patents will dissuade the meek and mild), I do have an XLR mounted phantom-powered direct box that could be directly connected to a guitar using one of those dual pedal plugs. However, I consider that a sufficiently bizarre idea that I doubt anybody would try it, so I don't consider myself a competitor.