jongor
First Lieutenant  Posts: 2 Registered: 2/25/2008 Status: Offline
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posted on 2/25/2008 at 21:56 |
For my first project I took an onboard preamp out of a bass and put it into
a stompbox so I could use it with other basses.
Here's a diagram from the manufacturer:
http://sadowsky.com/media/download/wiring_diagrams/preamp_w
iring.pdf
See how the 9v neg connects to the ouput "ring"? Is that right?
Electrically, verified with a continuity check, the ring is the same as all
the negatives in the circuit.
I did use a 9v power supply, not a battery.
The preamp works but I get some noise, could it be a ground loop?
And ideas would be welcomed!
thanks
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Guitar101
Moderator   Posts: 481 Registered: 12/22/2003 Status: Offline |
posted on 2/26/2008 at 00:15, Reply 1 |
want type of box are you using, abs, metal etc...
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jongor
First Lieutenant Posts: 2 Registered: 2/25/2008 Status: Offline |
posted on 2/26/2008 at 09:45, Reply 2 |
It's aluminum.
Also, I tested 3 different 9v power supplies and they were putting out
between 11-13 volts......?
Maybe that's the problem?
[Edited on 2/26/2008 by jongor]
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brian
Moderator  Posts: 1075 Registered: 12/22/2003 Status: Offline |
posted on 2/29/2008 at 13:04, Reply 3 |
You don't want that, it will burn up the circuit. Not sure why a 9v rated
power supply would read 11-13v
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Limbe
First Lieutenant  Posts: 4 Registered: 10/23/2008 Status: Offline |
posted on 10/24/2008 at 06:01, Reply 4 |
Hi Jongor and Brian!The connection from the negative side of the battery or
power supply to the "ring" of the jack is common practice but if you are
building the preamp as a stompbox you should do it on the input jack.Use a
stereojack as inputjack and connect the neg. side to the ring.When you plug
in your guitarcord(which has a monoplug) it will connect the minus to
ground(which is what you want it to do). For outputjack use a standard
monojack.The reason your power supplies put out more than 9 volt is because
they are unregulated . The voltage will vary depending on how much current
your stompbox will draw .Obviously yours draw very little current.If you
use a battery instead and the hum disappear you will know that the power
supply is the culprit which gives you a choice of A:use a 9 volt battery
or B:use a regulated power supply and finally C:add more filtering to the
supply you already have.
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