building a 'tiger preamp' unity buffer as used in jerry garcias guitars.

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i'm building a tiger preamp buffer for some 'jerry garcia' mojo...

i'm trying to keep it to a small footprint so i can attach it to my strap. i dont want it on-board, so i figure his is the next best way to do it.
just a 6" low capacitance cable from the guitar to the buffer, then my long cable to the pedalboard another to the amp...
gonna use some of those dano jacks as they are so small, wired perf style so i wont have any pad lifting breaking issues.
i'll try and post a few pics tomorrow if anyone is interested.as it wouldn't be a bad thing to have a strap with an onboard bypassable buffer right on it. just use it anytime you need low treble loss buffered signal right from your guitar...
and essential for getting those bright edgy 'jerry' type tones.

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ok, i got this thing together and tested it out, but after a little noodling i noticed i'm getting some snap crackle and pop...
if i tap the battery i can hear it through my amp, as well as moving the battery snap seems to crackle as well?
maybee a wonky bat snap?!?
or some crosstalk from the input r(100k) and the output? does that sound reasonable?!?
maybee that 9v filtering cap is bad?
hoping someone will take a look at the schem and see if theres anything that jumps out as a reason why this thing would crackle...

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i think it was a bad battery. one of the 3 batteries (all fresh) is acting microphonic! strange.

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after trying it out for a while, i figure i'd report in.
its slightly less than unity, and seems voiced a bit on the trebly side...
i also tried shorting out the 100k input resistor, a bit more full eq sounding, a bit louder as well, but wanted that 'jerry' hi-fi trebly tone.
works well. had no trouble driving a 25' chord and retaining its crispness...
that problem battery had me scratching my head tho!
so its one more step towards a decent jerry tone, next i think i'll perf up a fet-2b... see if i cant get that slightly overdriven fender input stage thing happening...
ive been using a blues driver as a sort of 'fender input stage' substitute, not bad really but it tends to be a bit grainy as opposed to compressed when its pushed...

[PRR]

> its slightly less than unity

The 100K in the front-end, against the 1Meg||1Meg, is 1.58db loss. 100 ohms at the end against 10K and typical amp input is another 0.1db, call it 1.7dB total loss.

That's "slightly less", as you say.

If it were a problem, you could change the 1Megs to 10Megs, 0.3db total loss, inaudible.

But you could turn-up your amp a half-notch to cover the loss, same thing.

> seems voiced a bit on the trebly side...

It is ruler-flat 34Hz to 6MHz. No "voice".

However you are comparing to a guitar cord. A naked pickup is 5K and 5H. Guitar cord is 300pFd, maybe more with amplifier. This produces a roll-off below 10KHz, often more like 3KHz (with a peak). So the "normal sound" lacks highs. The buffer can brute-force drive 300pFd to far-far beyond the audio band, you get EVERYthing.

Guitar pickups and speakers evolved to this upper-mid fall-off. The upper partials of a string are non-harmonic. They are dissonant, and not in a musically useful way. More of a high haze around the notes.

You usually "want" to limit the high end tones. With a wound pickup it happens that this also allows stronger bass and middle signal (more turns). Louder is always acceptable. High zingers won't be missed after a few songs or a few beers.

Yes, some guitars and some guitarists can use extended highs. Garcia is mentioned... note that Jerry and pals were pretty savvy electricans, and there may have been an ear-tuned low-pass somewhere in the amplification or in speaker-selection.

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thanks for the info PRR!, i appretiate it!

swapping the 1M's for 10M's is a great suggestion for maintaining @ unity, i'm gonna keep it as is for now. see how it works out live, but i may try that down the line...

note that Jerry and pals were pretty savvy electricans

Oh yes! believe me, digging into garcias signal chain was an eye opener for sure...

and there may have been an ear-tuned low-pass somewhere in the amplification or in speaker-selection.

From what I've read,right down the line, keeping the high end seems to be the theme.
buffer after the pickups,coil cut hb's usually,bf twin preamp with bass on 0,mcintosh ss power amp(hi-fi 20-20k freq r) into jbl e-120s.
it would seem that any treble rolloff happening would be from the bf twin and the e-120s rolloff @6k! still thats alot of high end!
Good thing he had a tone knob,but with the tone full-up that rig must have been insanely bright! there may be some other low pass filtering in there somewhere other than the speakers, but by most accounts it WAS insanely bright at times... no surprise there!

[PRR]

> and the e-120s

How many?

The monster rig had LOTS of 120s close together. Array loading improves the bass efficiency, does not affect treble. For 12" speakers, below 600Hz. Probably has 8db acoustic gain on the bottom notes. Certainly would not need the bass-boost available in the big Fender tonestack.

If this is for just a few speakers--- I don't know.

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Alot of e-120's! True
Now that you mention it,i do wonder weather the apparent 'treble heavy' signal chain has been balanced against some inherent 'bass heavy' aspect of the system. Like you mentioned, a linear array has an extended low end. Perhaps there is a balance being struck between the p.a. system and the signal chain before the mains. For me, my curiosity as to how and why they came up with the rigs they settled on, is my main motivator. rather than a desire to have all the right gear etc... its a unique system.