Guitar with built in buffer before volume pot

Started by facon, March 13, 2014, 11:54:54 AM

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facon

Hey,

I was wondering if anybody has any experience with placing a buffer (or boost) into a guitar before the volume and tone pots. I have been contemplating modding my Jazzmaster rhythm circuit. Since it has a switch location, I could use this to turn the buffer on and off for fuzz. I play live with "longer" cable runs of around 18ft. I'm wondering if this will help maintain more clarity.

I've noticed improvements by using a buffer directly before a standard volume pedal. Would this have a similar affect on the guitar tone? Usually, the buffer will help with the highs. However, a standard 250k volume pot is normally switched out for something like 25k in this situation.

guitarkill

Quote from: facon on March 13, 2014, 11:54:54 AM
Hey,

I was wondering if anybody has any experience with placing a buffer (or boost) into a guitar before the volume and tone pots. I have been contemplating modding my Jazzmaster rhythm circuit. Since it has a switch location, I could use this to turn the buffer on and off for fuzz. I play live with "longer" cable runs of around 18ft. I'm wondering if this will help maintain more clarity.

I've noticed improvements by using a buffer directly before a standard volume pedal. Would this have a similar affect on the guitar tone? Usually, the buffer will help with the highs. However, a standard 250k volume pot is normally switched out for something like 25k in this situation.

What you want is something to make up for the loss of highs due to cable capacitance. The Tillman Preamp should work for that. I have always used it right before the output jack of the guitar (after the controls).
just another dude killed by his guitar

facon

Thanks for the response. I've also managed to find this product: http://www.creationaudiolabs.com/redeemer/. It appears to be similar. Both appearing after the vol/tone pots. In the demo, you can hear that there is no high end loss while rolling down the volume. It seems that it really wouldn't make enough of a difference for me to place the buffer pre-volume and customize the volume pot because of it.

Since I know the exact length of the cable that I'll be using, would it be beneficial at all to calculate the cable capacitance and customize the output impedance to suit the exact setup? Is this thought getting into the ridiculous "only dogs could tell" zone?

R.G.

It's probably better to buffer after the tone/volume networks.

The T/V networks affect loading on the pickups and have an effect on the tone, making it what you expected. Buffering after them subtracts the treble loss from the cable loading.
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

facon

Sounds good. Thanks for chiming in! Now I just need to figure out what to do with my two extra pots in the rhythm circuit  :)

wavley

Quote from: facon on March 13, 2014, 01:20:41 PM
Sounds good. Thanks for chiming in! Now I just need to figure out what to do with my two extra pots in the rhythm circuit  :)

Fender Bottom Master (I have the made for America version that regrettably does not have the fuzz and the rhythm circuit, while I love it on my regular jag, is useless for a bass)



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guitarkill

Quote from: R.G. on March 13, 2014, 01:11:05 PM
It's probably better to buffer after the tone/volume networks.

The T/V networks affect loading on the pickups and have an effect on the tone, making it what you expected. Buffering after them subtracts the treble loss from the cable loading.

Exactly why I like right before the output jack.
just another dude killed by his guitar

enrique

Quote from: guitarkill on March 13, 2014, 02:39:03 PM
Quote from: R.G. on March 13, 2014, 01:11:05 PM
It's probably better to buffer after the tone/volume networks.

The T/V networks affect loading on the pickups and have an effect on the tone, making it what you expected. Buffering after them subtracts the treble loss from the cable loading.

Exactly why I like right before the output jack.
hi guys this is from my blog (emg pa-2 buffer and booster at your choice)
http://rcustomspedals.blogspot.com/2012/10/booster-basado-en-el-pa-2.html

diydave

I've been using the tillmann pre-amp (is boost, not buffer) for some years now, and I'm lost without it.
First I built it inside my fender jaguar - after volume and tone-pot and before the output-jack.
But it's not a good thing for the screw-holes of your guitar. You need to change the battery from time to time. And when you're in the middle of your set with a diying battery for your built-in boost...
So recently I switched to a pre-amp-cable (also on till.com, but he's using xlr-cables for it).
I used a normal guitarcable - the fet + gate & source-resistor are soldered directly to the jack (large Neutrik one). The cable runs to the box, where you find the rest of the circuit (drain-resistor, caps) and battery.
Better for the guitar.

digi2t

Quote from: diydave on March 14, 2014, 04:22:30 AM
I've been using the tillmann pre-amp (is boost, not buffer) for some years now, and I'm lost without it.
First I built it inside my fender jaguar - after volume and tone-pot and before the output-jack.
But it's not a good thing for the screw-holes of your guitar. You need to change the battery from time to time. And when you're in the middle of your set with a diying battery for your built-in boost...
So recently I switched to a pre-amp-cable (also on till.com, but he's using xlr-cables for it).
I used a normal guitarcable - the fet + gate & source-resistor are soldered directly to the jack (large Neutrik one). The cable runs to the box, where you find the rest of the circuit (drain-resistor, caps) and battery.
Better for the guitar.

How about this?

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diydave

QuoteHow about this?

Saw that one comming.
I'm no hero when it comes to drilling and sawing on a guitar.
But it's a solution for sure.

R.G.

Let me insert something - I designed an onboard preamp for a similar purpose deliberately to address the battery issue. The circuit was optimized for good buffering in a guitar and low current drain (hence longer battery life) and operation from two 3V lithium coin cells instead of a 9V battery. This is a considerably smaller battery pack.

See: http://www.diystompboxes.com/smfforum/index.php?topic=102719.0
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

digi2t

Quote from: diydave on March 14, 2014, 07:59:08 AM
QuoteHow about this?

Saw that one comming.
I'm no hero when it comes to drilling and sawing on a guitar.
But it's a solution for sure.

I hear ya. I don't mind modding a guitar, if it's for a good cause, but the battery case in the panel is a great compromise. Actually, save the original cover, and buy a blank. If ever you decide to sell the guitar, you can remove the preamp, and modded cover, and restore it to original form.
  • SUPPORTER
Dead End FX
http://www.deadendfx.com/

Asian Icemen rise again...
http://www.soundclick.com/bands/default.cfm?bandID=903467

"My ears don't distinguish good from great.  It's a blessing, really." EBK

wavley

There isn't a real good place to mount a battery box on a Jazzmaster, there are no cavities on the back like a Les Paul or Strat so you would either have to do some cutting to the wood or pickguard.  The advantage a jag has here is that there's a pickguard, but all of the electronics have their own panels.  I wouldn't worry about wearing the screw holes out, an old luthier showed me a trick where you just shove the wood end of a cotton swab in and break it off, then you screw back into it like normal, no more loose screw.

If it were me with a jazzmaster and I wanted to put a battery in it, I would just grab the control plate from a jag or maybe J-bass and then cut the pickguard so you don't have to take the whole thing off (including bridge and strings) to change a battery.
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facon

#14
I tried a buffer connected to the jack using a short patch cable today. Made a huge difference. I'm definitely moving forward with this.

Since the jack sits on top of the pickguard, I'm just going to use a small box with a male connector mounted on the front and a female on the rear side. I think this would alleviate all issues with an internal mount and allow me to use it on multiple guitars. I'll probably put a small push button switch for fuzz pedals. It should be similar to an old LPB-1, but with the jack at a right angle.

If you haven't tried this before, I really recommend giving it a shot. It made everything super touch sensitive and did not get ice picky. Not great for vintage smooth tones, but definitely a great option to have. It reminded me of the feel I got from playing a Fush Train 45.