Stratoblaster kit ordered, having second thougts

[RoadtoNever]

Looking for advice on whether I should reassess my choice for a booster kit and if so which one.

I ordered a Stratoblaster kit before I learned about impedance requirements for line-driving functionality. Maybe no biggie but I'm rather anal about signal loss from cable capacitance. Would I be advised to look into a different project? I hit the strings pretty hard at times so I still like the idea of warm/graceful overload from a JFET.
Would lower output Z of an opamp design mean lower noise? If so that might change my mind If I can be assured overloads are difficult to get.
Don't need that much gain 6-9 dB max would be plenty.

[RoadtoNever]

Found this in an older thread:

With something like the Stratoblaster, you can have a buffer and a booster in one simple design.  Just switch the bypass cap in (boost) or out (buffer).
cheers

Would that allow for lower the output impedance? I'm thinking of a 3PDT for the switch to add a 100k resistor in parallel with the output resistor while switching out the bypass cap. Maybe that's just ignirrnt?
Speaking of that, which one is the bypass cap?

Here the schematic: http://www.generalguitargadgets.com/pdf/ggg_sbb_sc_i.pdf

[brett]

Hi
RE: Would lower output Z of an opamp design mean lower noise? If so that might change my mind If I can be assured overloads are difficult to get.

The Stratoblaster won't give you any problems with output impedance. It's much lower than a pickup and volume control, for example.
The bypass cap isn't involved (but it is the one that runs parallel to (bypasses) the pot/resistor on the source of the JFET, or the emitter of a bipolar transistor).

The Stratoblaster is a really nice booster. Have fun 
cheers

[RoadtoNever]

I'm sure as you say I won't have any problems with an 100k output impedance. I'm truly anal about cable capacitance however. I haven't done the math outside of the guitar cavity but as an example lets say I loose 6 dB at 10kHz, no big deal but the same amount of capacitive load might raise 3.5kHz by 1.5 dB  and that's bad mojo for me. Again as an example if I was required to use a circuit that raises the noise floor by 6dB to maintain a smooth roloff so be it. Please understand my concern it's not merely audio-geekery but rather about maintaing tonal properties. Unless it seems like I've overlooked something fundamental please do tell about any viable mods for reducing output impedance in the Stratoblaster circuit.
EDIT:Also, being able to plug in directly to a line input would be nice for recording.

[Ronsonic]

It's a one-transistor gadget. It will take less than an hour to build and test and see if it does the job. Stop worrying.

If you are really worried about cable loading, etc. the blaster will be so vastly much better than the pickups alone that it will be a huge improvement. If you then decide that it isn't doing the job for you, you'll have a baseline and more knowledge about what to change and where to go next.

[PRR]

> problems with an 100k output impedance

Stratoblaster you linked has 17K output impedance. (The 22K drain load is the main cause, then the 100K bleed, and stray internal drain resistance.)

> cable capacitance however. I haven't done the math
> say I loose 6 dB at 10kHz, no big deal but the same amount of capacitive load might raise 3.5kHz by 1.5 dB

In a simple R-C network (Stratoblaster, not naked wound pickup), there is no "raise".

3KHz is important, but anything over 6KHz we probably won't hear through speaker and probably don't want to hear.

30 feet(!) of cable is 1,000pFd. 17K loaded with 1,000pFd is down 3db at 9K, 1db at 4.5KHz. This will generally be "no effect". Shorter cables will have less effect.

[RoadtoNever]

Oh, that should be fairly immune to cable capacitance. Thanks for clearing that up PRR! Should work okay with a line level input even. 
...Which makes me inclined at this point to just place it inside my guitar cavity and replace the pot with a fixed resistor.
...Which makes me realize I'm don't know my potentiometers. Where would I place the resistor on this board? http://www.generalguitargadgets.com/pdf/ggg_sbb_lo_gtr.pdf

[petemoore]

  Not to be picky but here I go:
  What is 'line level'...
   What is 'this resistor' ?
  That said, skipping-moving right along...putting the stratoblaster in the guitar...that was the originals design, I use a 12' cable to a pedalboard 'Box Stratoblaster and really like the sound with my rig, you can expect greatly improved cable-drive-ability compared to the guitar output, this is true with ~any active circuit.
  Perhaps one of these:

   http://www.smallbearelec.com/Detail.bok?no=619
 
   Will be a nice taper for both the PU output [original value is a good starting value choice] and the SB output, the DPDT choosing to bypass or go through the SB circuit.
    Further play with the pot taper [trim R?] or play with the SB's output so when the switch is pushed or pulled the volumes kinda match [or boost 'some']..
   

[RoadtoNever]

By line level I mean a standard 10kOhm low impedance input. Plugin directly into one would be useful for me at times. The 17k output impedance of the SB circuit I have should be sufficient? Maybe you happen to know some values I could change to make it work better in that capacity?

I really won't have any way of adding a control for the SB inside my guitar cavity as it's crammed with two dual-concentrics and a push-pull already in service. The 'resistor' I'm thinking about is fixed ~50kOhm and replaces the pot for unity gain(and space-saving). As for which hole it shall go in to I realize now I could just read the pot with my meter

[RoadtoNever]

Didn't have my facts straight, a line input requires a 1kOhm source

Could I get the output-Z down to that by lowering the drain and bleed resistors?

[kurtlives]

Maybe no biggie but I'm rather anal about signal loss from cable capacitance. Would I be advised to look into a different project?

Chill out man, play some guitar. 

[RoadtoNever]

I play guitars all the time. In fact I'm tapping chords with my left hand as I type this 

[DavenPaget]

Didn't have my facts straight, a line input requires a 1kOhm source

Could I get the output-Z down to that by lowering the drain and bleed resistors?

Don't bother .  The stratoblaster was designed to be a preamp and not a buffer , use it straight to a pedal/amp .
I built one blaster that was done by aron , it was awesome .

[elenore19]

Looking for advice on whether I should reassess my choice for a booster kit and if so which one.

I ordered a Stratoblaster kit before I learned about impedance requirements for line-driving functionality. Maybe no biggie but I'm rather anal about signal loss from cable capacitance. Would I be advised to look into a different project? I hit the strings pretty hard at times so I still like the idea of warm/graceful overload from a JFET.
Would lower output Z of an opamp design mean lower noise? If so that might change my mind If I can be assured overloads are difficult to get.
Don't need that much gain 6-9 dB max would be plenty.

The stratoblaster is awesome. I've built a couple. I would say you might as well just build it up and see if you like it. You can always build another boost.

[petemoore]

  Even thinking about it after the fact... the Stratoblaster is cool boostage.
   IF you need a buffer, try ~any commercial pedal, the input and output switching is done with Jfet which also serves as buffer in bypass mode, otherwise a buffer is a pretty simple build and might be easy to fit to the output and put in the Boosters box.

[Scruffie]

Not to say I don't respect your attention to detail, infact I envy it but....

One thing a lot of us guitar players forget is... are the audience gunna care or notice? 

'That guys Fuzz Face is a silicon one! Booooooo! When he rolls off his guitar volume it might not clean up as well and the sound is slightly harsher'

If ya sound good, who gives a crap, i'm guilty of worrying too but with a little bit of diversion... meh, I rarely use the *correct* components in builds now.

Of course if it really is gunna @#$% the sound for some reason, go all out, but it usually isn't.

[Minion]

I built a little opamp based on board buffer/booster that I installed in my ESP electric guitar that did the job of reducing the effect of cable capacitance and adding a bit of gain to help drive the input tubes of my amp , the effect was nothing short of miraculous , I have since installed them on several of my friends guitars and have sold several localy and on-line ......

I posted the schematic and PCB design here a couple years ago , if you do a search you can probably find it , if not message me and I"ll send you the design .....

[hawk900]

Looking for advice on whether I should reassess my choice for a booster kit and if so which one.

I ordered a Stratoblaster kit before I learned about impedance requirements for line-driving functionality. Maybe no biggie but I'm rather anal about signal loss from cable capacitance. Would I be advised to look into a different project? I hit the strings pretty hard at times so I still like the idea of warm/graceful overload from a JFET.
Would lower output Z of an opamp design mean lower noise? If so that might change my mind If I can be assured overloads are difficult to get.
Don't need that much gain 6-9 dB max would be plenty.

I'm actually working on your exact same desire right now.  
OK your input voltage is 9v so here's the math.  Power up the board with everything soldered together not installed in the guitar. Use a multimeter and make sure you have a fresh battery and confirm the 9volts on the curcuit board.  Now measure the volts on the in input of the gain pot. Should still be 9 or close to. Write volt down including after decimal points. Now crank the gain knob full blast and measure the volts same step as input but on the out put. It will be a higher value than 9.
Now take the gain output voltage reading and divide by the input voltage read from input of gain pot. This will give your gain ratio. Now google gain ratio to decibel calculator and when you input the values of the gain ratio it will show you exactly how much DB's are getting spit out. eg If the answer is answer is between 12 to 18 db's that would be ideal and an easier fraction because you just have to cut the 50k pot in half presuming thats the pot you have. So if the case you can solder a 25k resitor in its place to cut the 12 to 18 in half eg 6 to 9 db's. I know exactly what you are looking for. 6db's is the sweet spot on op amp guitar that give you a super clean non distorted boost for even the craziest of cable runs. The original design by alembic is a non adjustable 6db output from back in the early 70's. With these newer ones they brag about the quality distortion the gain booster creates once you crank it up to a curtain point. That's not what we were looking for when you think guitar pre amp. You want a solid no loss signal that is clean the way your type of pickups were meant to sound. If I want great distortion I use my vintage DS-1 and or my tube screamer pedal.
I run my sg like this. First routed out an insulated the pup cavity to house 3 buckers instead of the gibson standard neck and bridge. I use dimarzio DP104's . Super range ,sensitivity and clean as I've ever heard.
Pickup signal>tone knobs>stratoblaster out through all my fx and back into the guitar to the volume jack. The benifit of this that your fx which are volume sensitive see a constant signal with no drops and or gains at all times which will won't effect volume sensitive pedals like eg. Envelope filters ,etc. So you can preset all your fx to the way youlike em and no matter what you do with your guitar volume knob the settings on your pedals will sound the same as your setup them up to your preference. From the guitar volume which heads into my 67 fender twin in which I tapped the the output from the tone stack aka amp preamp tap out through the back to the mac daddy McIntosh 2300 that fuels a custom russian birch cab that houses two JBL E-120's 8ohm.
Here's an example schem the way mine is wired from the guitar innovator of all Mr.Garcia.

The bridge and neck share the same tone knob because they are never in us at the same time. I also split my coils for thee most cleanest tone from a bucker.  The middle pup I split and use the south coil and on the the neck and bridge I split and use the north coil. Also I don't use factory pup selector switches. I have each pup wired through a spst switch and can turn on a sweet combo like middle and neck while being split ofcourse which produces an amazing lead tone that beautifully harmonizes with each other and are magnetically in phase=no hum. To turn the addition neck coil on the switch is a pinky distance away from my picking so going from strumming and singing to lead is a simple pinky flick with no knob fiddling. Another cool rythym to lead trick is grab a rocking volume pedal like the rocking wah and remove the return spring out of it. So you can boost your lead volume with having to hold your foot on it the entire time. Then just tap the off end of the pedal to return to strumming.
I'll be working on this in the next few days in my free time and if I get the exact value rsesitor unless anyone here beats me to it. I'll post that with a shematic 4 u.
How do you know the sweet spot range between 6 and 9. Are you a Jerryist???guitar player.
hawk.
ps. The bottom switch is fx loop bypass switch but still leaves the stratoblaster on at all times.

[DavenPaget]

Didn't have my facts straight, a line input requires a 1kOhm source

Could I get the output-Z down to that by lowering the drain and bleed resistors?

Don't bother .  The stratoblaster was designed to be a preamp and not a buffer , use it straight to a pedal/amp .
I built one blaster that was done by aron , it was awesome .

Actually i meant , designed by Mark or (IvIark)