I've successfully used the JLM AC/DC, and Trex2 to rack some Studer modules into 3 separate enclosures.
For one two of them I used a Trex2 with TIP127s installed and reversed capacitors to get a secondary -ve supply from the main negative rail supply (while I kept the +48V components installed on the AC/DC kit but have it adjusted to minimum with nothing connected as I don't need phantom power).
I now have a small Studer mixer (with 6 input modules and 2 for the master output) that needs a new power supply. Unlike my other builds: I'd rather install an LM337 (instead of LM317 for +48V) onto an AC/DC, as the mixer doesn't need phantom power but does require -8V for the limiter section of the two output modules.
My other options are daisy-chaining a modified Trex from the -ve rail of an AC/DC kit or getting a Powerstation (with 1 +ve and 2 -ve rails will be used while the second +ve and +48V rail would be populated but unused). The main issue is that I want to minimize the components installed and avoid using a modified Trex.
I'm uncertain how much current the -8V rail needs but the mixer (when I checked with a power-meter before I decided to re-calibrate everything) used around 18W.
My biggest concerns are:
-if I can get away with getting a Powerstation and leaving the components for the sections that won't be used (+48V and the second +V rail) unpopulated
-if I can reverse the polarity of specific components and install an LM337 instead of a LM317 in the +48 section of the AC/DC kit and maybe even increase the current for 48V
As the mixer uses less than 20W- I'm certain most of the power is needed for +/-15V but am not sure exactly how much current the -8V rail needs to be.
Any help is greatly appreciated.
Reversing components to get -48V instead of +48V
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Re: Reversing components to get -48V instead of +48V
The title says -48v but in the text you say -8vdc?bxt403 wrote:I've successfully used the JLM AC/DC, and Trex2 to rack some Studer modules into 3 separate enclosures.
For one two of them I used a Trex2 with TIP127s installed and reversed capacitors to get a secondary -ve supply from the main negative rail supply (while I kept the +48V components installed on the AC/DC kit but have it adjusted to minimum with nothing connected as I don't need phantom power).
I now have a small Studer mixer (with 6 input modules and 2 for the master output) that needs a new power supply. Unlike my other builds: I'd rather install an LM337 (instead of LM317 for +48V) onto an AC/DC, as the mixer doesn't need phantom power but does require -8V for the limiter section of the two output modules.
My other options are daisy-chaining a modified Trex (which is what I'm trying to avoid) from the -ve rail of an AC/DC kit or getting a Powerstation (with 1 +ve and 2 -ve rails will be used while the second +ve and +48V rail would be populated but unused).
I'm uncertain how much the -8V rail needs but the mixer (when I checked with a power-meter before I decided to re-calibrate everything) used around 18W.
My biggest concerns are:
-if I can get away with getting a Powerstation and leaving the components for the sections that won't be used (+48V and the second +V rail) unpopulated --if I can reverse the polarity of specific components and install an LM337 instead of a LM317 in the +48 section of the AC/DC kit and maybe even increase the current.
As the mixer uses less than 20W- I'm certain most of the power is needed for +/-15V but am not sure exactly how much current the -8V rail needs to be.
Any help is greatly appreciated.
If -8vdc Best to use a powerstation and it is fine to not use or not fit the rails you don't need. So you can have +/-15v & -8vdc on a 2 x 18vdc power transformer.
The LM337 and LM317 pinouts are not the same so reversing can work but is a mess due to the pinout problem and reversing the 48v section is even worse.
If you need -48vdc can you send me the schematic of the desk so I can have a look at what is it doing with the 48v
Joe
JLM Audio
Capturing Audio without Injury
JLM Audio
Capturing Audio without Injury
Re: Reversing components to get -48V instead of +48V
Since the 48V rail is adjustable (to lower voltages) on all the JLM power kits: I figured I might as well ask the generalized question first (since I used the 48 rail from an AC/DC with a Trex2 to supply 5 VDC for logic and 3VDC for LED on one of the modules). I figured I could do something similar with an adjustable -48 Volt rail (in that I can just adjust it to -8VDC since I only need one extra voltage outside of the main +/- DC rails).Joe Malone wrote:The title says -48v but in the text you say -8vdc?bxt403 wrote:I've successfully used the JLM AC/DC, and Trex2 to rack some Studer modules into 3 separate enclosures.
For one two of them I used a Trex2 with TIP127s installed and reversed capacitors to get a secondary -ve supply from the main negative rail supply (while I kept the +48V components installed on the AC/DC kit but have it adjusted to minimum with nothing connected as I don't need phantom power).
I now have a small Studer mixer (with 6 input modules and 2 for the master output) that needs a new power supply. Unlike my other builds: I'd rather install an LM337 (instead of LM317 for +48V) onto an AC/DC, as the mixer doesn't need phantom power but does require -8V for the limiter section of the two output modules.
My other options are daisy-chaining a modified Trex (which is what I'm trying to avoid) from the -ve rail of an AC/DC kit or getting a Powerstation (with 1 +ve and 2 -ve rails will be used while the second +ve and +48V rail would be populated but unused).
I'm uncertain how much the -8V rail needs but the mixer (when I checked with a power-meter before I decided to re-calibrate everything) used around 18W.
My biggest concerns are:
-if I can get away with getting a Powerstation and leaving the components for the sections that won't be used (+48V and the second +V rail) unpopulated --if I can reverse the polarity of specific components and install an LM337 instead of a LM317 in the +48 section of the AC/DC kit and maybe even increase the current.
As the mixer uses less than 20W- I'm certain most of the power is needed for +/-15V but am not sure exactly how much current the -8V rail needs to be.
Any help is greatly appreciated.
If -8vdc Best to use a powerstation and it is fine to not use or not fit the rails you don't need. So you can have +/-15v & -8vdc on a 2 x 18vdc power transformer.
The LM337 and LM317 pinouts are not the same so reversing can work but is a mess due to the pinout problem and reversing the 48v section is even worse.
If you need -48vdc can you send me the schematic of the desk so I can have a look at what is it doing with the 48v
In any case: it seems like the process to get a -48VDC rail from the phantom power rail on a Powerstation or AC/DC kit is more complicated than getting a -ve supply from a Trex.
A partially populated Powerstation kit is probably the best option, as I won't be under powering anything.
Thanks.
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Re: Reversing components to get -48V instead of +48V
Yes part built powerstation will make it easy.
Whenever using the 48v rail for low voltage don't fit any jumper to doubler/tripler and short out C1 & C2 so turn the rail back into a normal power rail to set for low volts.
Always run a series resistor on leds and use a higher voltage rail. If no resistor and the rail voltage varies slightly or the led goes short it will not end well.
Whenever using the 48v rail for low voltage don't fit any jumper to doubler/tripler and short out C1 & C2 so turn the rail back into a normal power rail to set for low volts.
Always run a series resistor on leds and use a higher voltage rail. If no resistor and the rail voltage varies slightly or the led goes short it will not end well.
Joe
JLM Audio
Capturing Audio without Injury
JLM Audio
Capturing Audio without Injury
Re: Reversing components to get -48V instead of +48V
I double-checked and remembered the builds uses a Powerstation (the AC/DC was for another module). I was using the 48V rail to supply +ve to the Trex2 but switched the one of the V+ supplies instead.
I must've been under powering everything connected to the Trex2 since the LEDs were dimmer (albeit the logic circuits and CPU on the module were still functioning).
In any case: at least I know the mixer will have ample power (as it only needs around 20 Watts for everything). I look forward to getting another Powerstation, as the 980 module (which has also uses a microcontoller/CPU) is working perfectly.
Thanks.
I must've been under powering everything connected to the Trex2 since the LEDs were dimmer (albeit the logic circuits and CPU on the module were still functioning).
In any case: at least I know the mixer will have ample power (as it only needs around 20 Watts for everything). I look forward to getting another Powerstation, as the 980 module (which has also uses a microcontoller/CPU) is working perfectly.
Thanks.