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Double Bass Raven Labs PMB wall wart alternative
- Thread starter Jeff Bonny
- Start date
Just wire as if the two independent ports you plug into are 9V batteries knowing how polarity works. I do suspect you have to tie the 2 "batteries" to work. I found if you put the 18volt difference between tip and ring it works without a ground/sleeve connection. Looking forward to your results as between us we then rescue a bunch of Raven labs gear.
For those who don't want to do wiring, I suspect if you asked the Voodoo Lab guys nicely they would make one for you. They make a voltage doubler cable for 2 independent 9 volt ports for something like 6 dollars plus shipping. Then you would make what I made for the Dunlop 18V supply or get them to make the full up deal for you for an additional custom charge. I have done two gigs with just the tip and ring supplying power and no ground connection. Seems to work and the unit is "happy".
It mighty work, but generally this is not the case or you might get some distortion or at worst it damages the unit.
It only works without a ground without any problem, in then current Flow on both, positive and negative to ground is the same.
If not, then the voltages will differ ( so that both currents are the same, moving the virtual grounded) and you might get some or more distortion or if voltages exceed the limit the opamps max get damaged.
The absolute currents are not so much important, but the relation of the two currents is.
In simpler devices the currents are often very similar, so you might not find any difference to a grounded dual power supply.
I just thought I might explan what happens and why it max work or not.
It only works without a ground without any problem, in then current Flow on both, positive and negative to ground is the same.
If not, then the voltages will differ ( so that both currents are the same, moving the virtual grounded) and you might get some or more distortion or if voltages exceed the limit the opamps max get damaged.
The absolute currents are not so much important, but the relation of the two currents is.
In simpler devices the currents are often very similar, so you might not find any difference to a grounded dual power supply.
I just thought I might explan what happens and why it max work or not.
In my case I place a very nicely regulated 18 volts DC between the + and -. The current on the plus leg is by definition the current on the minus leg. In the case of the Raven Labs unit, it creates its own ground reference how I am doing it. With the approach of using two regulated isolated 9 volts DC supplies the ground seems to me might be more of an issue as the voltages/currents are not necessarily the same for each leg.
Reporting back:
I ditched the T-Rex and went with a Voodoo Labs 4x4 which has lots of current and lots of outlets, and options for 9 and 12 v power.
Wired -9vdc to tip, +9vdc to ring, and tied the remaining + and - outputs together.
Works like a charm, and the Raven sounds better than it ever did on batteries - the supply is VERY good.
I do, however, now need a larger road-case briefcase in which to store the Raven and volume pedal, but that's a minor annoyance.
Thanks to all for the wiring help.
I ditched the T-Rex and went with a Voodoo Labs 4x4 which has lots of current and lots of outlets, and options for 9 and 12 v power.
Wired -9vdc to tip, +9vdc to ring, and tied the remaining + and - outputs together.
Works like a charm, and the Raven sounds better than it ever did on batteries - the supply is VERY good.
I do, however, now need a larger road-case briefcase in which to store the Raven and volume pedal, but that's a minor annoyance.
Thanks to all for the wiring help.
