Onboard booster/preamp

[Seven64]

Hey, i did some searching last night for an onboard guitar booster/preamp, and found one that uses a J201.  I am in the process of building it, but it says each pickup needs one....does this mean i have to stuff three 9v's inside my strat?  i was trying to find one that uses an IC, but had no luck.  I am just trying to build a nice signal booster that can be switched on/off with a spdt switch on my fretboard.

http://www.till.com/articles/GuitarPreamp/

thats what i found

[StereoKills]

You shouldn't need one for each pickup. IIRC all the Tillman preamps I've seen have been placed at the output of the guitar.

[Gurner]

One onboard preamp will be just dandy unless you have some FET fetish going down.

I think you've seen this bit & got confused...

"Notice that some of the details are left to the reader's imagination because there are so many ways to use this preamp.  For example:

Mount it on-board the guitar, after the pickup selection switch, volume and tone controls.
Use a separate preamp on each pickup. "

Note....that it's just an idea .....and likely aimed at those who have no other form of mental relief.

[familyortiz]

Keep in mind that those J201's vary wildly and the performance will vary just as much, so don't be surprised. Just sayin'

[Mark Hammer]

In some instances it can be preferable to have an active gain/buffer stage for each pickup, simply to provide isolation/non-interaction for certain types of controls.  For example, if the planned electronics include some sort of continuously variable blend control, it may be helpful to isolate each pickup by means of an individual preamp stage.

Again, the emphasis is on "can be", not "is" preferable.

If you simply want to assure that you don't lose highs over a longish cable, and/or want a little more muscle to your sound, a single JFET preamp for the entire instrument is sufficient.

I regularly warn folks not to go crazy with the gain since it can actually interfere with optimal functioning of some effects.  What you shoot for is something that optimizes signal to noise ratio without compromising clarity or tone of other devices.  YMMV, but I figure a gain somewhere in the 3-4 range hits that target.  Bit of a six-pack, but not so muscle-bound you can't fit in a suit.

[Ben N]

Check out also the Paul Marossy variation on the Tillman here, especially for a switchable level boost. The original fet onboard boost is the Stratoblaster, also worth a look, especially if you (a) don't want the preamp on all the time, and (b) want a hefty boost when you do switch it on.

There are special cases where separate buffering or preamping of pickups may be desirable. Some EMGs pickups have preamps built-in. This is a much easier thing to do space-wise if you can deal with SMD boards and components, and may make sense together with designed-for-the-purpose, low-impedance, center-tapped dual coils feeding a diff-amp, mic-preamp style. (There is a DIY project for such a thing at the other forum, but it is not for the faint-of-heart, unsteady of hand, or dilettantes like me.) There was also an article in GP about on-board preamps that I read long ago (maybe Anderton's Clarifier article? But I digress.) in which the intent was to boost only one of the pickups that the author thought needed the boost. Not really applicable to most guitarist's needs, either. Another possibility is when mixing piezo and magnetic pickups, and separately buffering the two types of inputs before mixing may be desirable. But, as stated above, for adding in to an existing, conventional guitar with conventional pickups, a single fet preamp should be just as good as two or three.

[Mark Hammer]

I think that one of the things we consistently overlook when it comes to onboard electronics is that the "chassis" was not designed for it.  As a group we take our 1590Bs and BBs, and apply fairly standardized layouts to them.  We know where this and that is going to go.  On a guitar, however, we tend to be winging it, and making it up as we go along.  All of which too often leads to wiring that is prone to bad layout or mechanical noise.

So for my part, unless it really needs to be done inside the guitar, I figure far better to do it off the guitar if possible.

The Tillman preamps, and many similar, can be built into a phone plug.  Hell, I built my very first JFET preamp into the head of a rat (well, attached to his skull), so building one into a plug with a slightly larger barrel cover is no big whoop.

[sault]

For my guitars that don't already have active pickups, I've installed an onboard buffer. Simple stuff, just an op-amp (TL072), but no problems with noise, especially since there's no extra gain. Make sure your pickups are properly wired and grounded anyways, and you shouldn't have any problems.

I don't feel like I need any extra gain... the multifx units that I've used don't like really high output signals, so I'm already operating with lowered pickups. I have a relatively high-output pickup in the bridge position, a Seymour Duncan Alternative 8, so with as much as a 2v peak-to-peak signal, if I had any gain I might be clipping.

That said, there is far less signal loss even with just using a buffer. Its nice! IMHO, it should be standard to have one of these on every guitar... a low output impedance means less interaction with cable capacitance, so you can use even crappy cables without suffering any tone loss. I'm cheap - I'd rather spend the time and money installing (or having someone else install, because my work looks like a rat's nest and their work looks like it should be hung on a wall and admired) a buffer than buying freakin' 60-80 dollar cables!!!

Anyways, an opamp can get closer to the rails than a Jfet or even a Mosfet, so why not take advantage of it? The average output will be less than 1v peak-to-peak, and that's well within an opamps linear region.

My two cents...


Saul t

[MikeH]

Like the others said, you only need one.  But If you wanted to use on on each pickup, you wouldn't need 2 9v batteries, you just hook both up to the same battery in parallel. 

[petemoore]

  The Stratoblaster...without so much 'blast'.
   Perf-''divingboard''-epoxied on the back of a DPDT/100kL [pullshaft/switch].
  Wired so the pickup, or the pu>preamped feeds the 100kLpot [w/tapering R's added to curve the linear pot taper.
   Set up so the stratoblasters original 'gain/volume' control is then fixed value preset-gain, ~just above unity [set pot to sound/measure/replace with fixed R.
  I found out 'a dab'll do ya'..a bit less 'blast' [pulling the switch and opening up the SB] at the amp input made it difficult to 'deftly switch', toned back by presetting gain~above-unity with a fixed resistor to replace the SB pot.
   Jeff's into the accoustic/w/magnetic PU, with nothing but 1 strech of guitar cable on the floor. I sent him one of the above to try out, he calls it 'perfectly amazing..', I call it a fine set of compromises, very complimentary feature which helps achieve his tone-goal. [a switch to drive what becomes> the next preamp a bit harder]. He has a buncha guitars so I sent him another one because I got the idea he thought it was a buncha trouble for me and said he didn't need it..it installed immediately into his guitar anyway, and again did the sound-goal-achievement thing/close enough was 'perfect', different of course because these are two accoustics/w different PU's. He just leaves 'em on mostly though, and pulls the battery [through the soundhole] when he puts G in case.