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Post by strat80hm on Sept 10, 2016 15:32:52 GMT -5
How to properly wire a added volume pot my acoustic guitar equipped with Fishman-presys-preamp (active piezo) without draining the 9V battery?  - Since i installed a volume pot, the 9v battery runs out in a couple of days - big hint for a wrong wiring letting the circuit on all the time - Acoustic guitar active preamp turns on when a jack is plugged - and off when unplugged, i d like to keep that!  I connected that volume pot on the red wire and made sure the ground would connect only when a jack is plugged in - but apparently this is not working and the battery is dying out even when not plugged. Anyone know what d be the proper way to do this? |
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Post by JohnH on Sept 10, 2016 19:25:51 GMT -5
when you have a new battery, does it then work as it should (until it drains)? any other quirks while it works?
If that is all good, then a wild guess is that the correct lug for the hot wire is being used to go to the jack, but battery is on the wrong lug. the battery negative should be on the lug that only connects to the one with the main circuit ground when a mono jack is inserted. Its really only a guess.
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Post by strat80hm on Sept 11, 2016 13:25:59 GMT -5
Hey John,
It does indeed - system works perfectly till battery drains down to 7-8Volt, below that the battery led blinks.
As of now i remove the battery between gigs (daily)
That is a good question: how do i figure this out? should i reverse my wiring?
This is the FIshman Presys - piezo is directly wired inside preamp (no plug)
Preamp output is a plug (Molex connector) type with the 3 wires (red, white, black)
black is grounded
white goes to rind
red goes to tip - this is the one i choose to insert the volume pot
Thanks for your lights
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Post by JohnH on Sept 11, 2016 15:11:46 GMT -5
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Post by strat80hm on Sept 12, 2016 1:58:33 GMT -5
Thanks for this diagram - that looks kinda similar, yet different. I ll look into it to determine which cable is the battery.. |
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Post by strat80hm on Sept 12, 2016 20:18:22 GMT -5
Here s the battery-draining wiring - does it speak to you?  ![]() |
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Post by JohnH on Sept 12, 2016 22:08:10 GMT -5
Here s the battery-draining wiring - does it speak to you? ![]() Yes, it says; "move the black wire which is connected to the pot, from the 'ring' lug to the 'sleeve' lug." |
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Post by strat80hm on Sept 12, 2016 23:21:09 GMT -5
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Post by JohnH on Sept 13, 2016 5:16:45 GMT -5
with the battery, It seemed like the white wire is used as battery negative on Fishman systems. If it goes to the ring, and its the only thing that does, then when you unplug, one end of the battery is connected to nothing and no current can flow.
I cant quite tell about the kill switch. When you press it to kill the sound, does something get disconnected?, or does something get connected?
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Post by sumgai on Sept 13, 2016 11:57:55 GMT -5
John,
According to the eBay description, the unit will 'connect' when physically pushed by grounding the pickup selection switch output. (The more desirable way to implement a kill function.) It would appear that if this is the case, then it could be connected anywhere in the circuit, my personal preference being the tip terminal of the jack itself. Of course, that's because of the wide variety of circuits that could possibly be installed before said output jack... when all is said and done, that jack is the final arbiter of what's going out to the amp (or pedals), so that's the logical choice to mount the thing, amiright? 
I do notice that this unit has a knurled split shaft. That's nice for Strat style knobs, but I wonder how many other kinds of guitar knobs won't/can't accommodate this thing, thus reducing the seller's market. 
HTH
sumgai
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Post by strat80hm on Sept 13, 2016 14:41:53 GMT -5
with the battery, It seemed like the white wire is used as battery negative on Fishman systems. If it goes to the ring, and its the only thing that does, then when you unplug, one end of the battery is connected to nothing and no current can flow. I cant quite tell about the kill switch. When you press it to kill the sound, does something get disconnected?, or does something get connected? Thanks for clear explanation - white wire should stay by itself on the ring - i guess i had the same mistake on my other volume-pot-equipped acoustic. Yes, when you press it, it grounds the signal - though on my other guitar, when doing so, that would turn that LED light on the preamp that usually briefly turn on at the moment you plug a jack in. |
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Post by strat80hm on Sept 13, 2016 14:46:51 GMT -5
John,
According to the eBay description, the unit will 'connect' when physically pushed by grounding the pickup selection switch output. (The more desirable way to implement a kill function.) It would appear that if this is the case, then it could be connected anywhere in the circuit, my personal preference being the tip terminal of the jack itself. Of course, that's because of the wide variety of circuits that could possibly be installed before said output jack... when all is said and done, that jack is the final arbiter of what's going out to the amp (or pedals), so that's the logical choice to mount the thing, amiright?
I do notice that this unit has a knurled split shaft. That's nice for Strat style knobs, but I wonder how many other kinds of guitar knobs won't/can't accommodate this thing, thus reducing the seller's market.
HTH
sumgai
Thanks for input Sumgai - i too want that pot to be the master volume/master killswitch of the entire guitar, thus last last in the chain Do you think not all knobs would fit on this? actually i use a wood knob borrowed from another guitar for now.. |
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Post by sumgai on Sept 13, 2016 17:31:48 GMT -5
8Oh,
It's a rare Gibson knob that works on a knurled split shaft. Most of them have a smooth shaft with one flat side. The knob is made to fit that, and is held on either with a set screw, or a spring-loaded metallic insert that grabs the flat portion of the shaft. The control is mounted such that the "10" comes to point where the user wants it to point. Some earlier controls/knobs used only a smooth side, with no flat spot. These most likely used a set screw, as it'd be pretty hard to fit a springy piece of metal in there too. Even so. there have been tightly fitted press-on knobs for these controls as well. I image that after some usage, they will start slipping, but then, whadoiknow, eh?
Your guess about where to place the kill button sounds like the right way to go. In effect, it's a "mute" button, and for most activity, it's the quietest operation in terms of clicks or pops when operated. But be aware....
Presume that on your Master Vol control, you short the incoming hot wire to ground, instead of the wiper. If the wiper is not at '10', then it is somewhere between the incoming hot lead and ground, right? In such a case, we say that the wiper is suspended between the two, and thus it is not holding the amp input at ground potential. This gives rise to possible noise issues, meaning humming or buzzing and such. Better to short the wiper terminal to ground with the kill switch, which grounds the amp's input too, thus make sure that all is quiet on the Western Front.
Which is why I advocate for hooking up the switch right at the very jack itself - no chance of accidental 'suspension', or worse, not working at all because of some other wiring mistake. I'm sure you take my meaning, amiright? 
HTH
sumgai
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Post by reTrEaD on Sept 14, 2016 22:47:03 GMT -5
It's a rare Gibson knob that works on a knurled split shaft. That seems strange to me. Every Gibson I've ever owned or worked on had a splined split-shaft pots and push-on knobs. Fender Telecasters, Precision Basses, and Jazz Basses have smooth shafts and require knobs with set-screws, though. |
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Post by sumgai on Sept 15, 2016 3:28:23 GMT -5
^^^^ Obviously we've worked on different guitars!
Come to think on it though, my previous Strat had knurled split-shaft jobbies, but my newest acquisition has smooth shaft units. The insides of the knob are minutely splined, and that's probably what makes them stay in place. Can't be sure though, unless I wanna subject it to the 'Madman From Motor City' test regimen. 
So, in slight retrospect, I should not be so emphatic that all knobs of a given type belong to any one particular manufacturer. I must've forgotten the golden rule, and that is, the gold goes to the lowest bidder whenever the parts bins are empty. But for sure, that isn't always the same bidder, n'est pas?
Mea culpa, and all that.
sumgai
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Post by strat80hm on Sept 16, 2016 18:48:55 GMT -5
I cant quite tell about the kill switch Lil update: i wired everything as suggested - included kill-pot specials - and so far everything works fine and the battery LED hasnt even blinked since! Thank you you Nutz! |
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