I am building a 15 vdc dual psu (+15 and -15 rails) to be used to opwer opamp projects (like phono stages etc). I was thinking of using 3 pin XLR connectors to get the voltage to the device, I don't see any reason why I can't but I want other opinions.
I want to use XLR because the chassis plugs look clean, I can put a female on the psu and male jacks on the device(s). And one XLR cable will be all I will need once built.
Opinions?
I want to use XLR because the chassis plugs look clean, I can put a female on the psu and male jacks on the device(s). And one XLR cable will be all I will need once built.
Opinions?
As a connector, the original (circa early 1950's, I believe) XLR-3 design was rated for a surprising amount of current and operating voltage. I don't know if the modern descendents of Canon's engineering efforts retain those characteristics or not. If so, the XLR-3 could be a reasonable choice as a power interconnect connector for everything from preamps to power amps (either vacuum tube or solid state). And, they look sexier than anything Molex has ever dreamed of!
The biggest disadvantage is that over the last 60 years or so, XLR-3 has become THE connector for balanced signal lines. It's not uncommon to hear "XLR" used synonymously with "balanced signals". Consequently your power interconnects are likely to be mistaken for signal cables and connected accordingly - either by accident, or because somebody doesn't understand the cables' function.
It's doubtful that any harm would come if a signal line was plugged into the connector where your preamp receives its supply power. I suppose there might be some damage from residual capacitor charge if the preamp's power port was connected to a low-level signal input, such as a microphone input. Most low-level inputs have protection circuitry that can handle this case. Likewise there's a pretty low likelihood for damage if a signal SOURCE - such as a line driver output - was plugged into the preamp's power port. The power circuits will show a very low impedance at audio frequencies, which may activate protection circuitry in the source or driver, but any source that can operate into a short circuit without permanent damage should be safe.
The problem comes when your power supply (PSU) output gets accidentally connected to an audio signal circuit. Whether it's an audio input, or an output, the supply votage may be more than it can withstand.
So this is an idea that has some associated human problems, but technically it has merit. If you go ahead with it . . .
The biggest disadvantage is that over the last 60 years or so, XLR-3 has become THE connector for balanced signal lines. It's not uncommon to hear "XLR" used synonymously with "balanced signals". Consequently your power interconnects are likely to be mistaken for signal cables and connected accordingly - either by accident, or because somebody doesn't understand the cables' function.
It's doubtful that any harm would come if a signal line was plugged into the connector where your preamp receives its supply power. I suppose there might be some damage from residual capacitor charge if the preamp's power port was connected to a low-level signal input, such as a microphone input. Most low-level inputs have protection circuitry that can handle this case. Likewise there's a pretty low likelihood for damage if a signal SOURCE - such as a line driver output - was plugged into the preamp's power port. The power circuits will show a very low impedance at audio frequencies, which may activate protection circuitry in the source or driver, but any source that can operate into a short circuit without permanent damage should be safe.
The problem comes when your power supply (PSU) output gets accidentally connected to an audio signal circuit. Whether it's an audio input, or an output, the supply votage may be more than it can withstand.
So this is an idea that has some associated human problems, but technically it has merit. If you go ahead with it . . .
- Consider finding a way to prominently identify the PSU-related connectors. Perhaps make them some garish color - neon violet, fluorescent green, etc. A high-quality spray paint or model enamel may be all that's needed. Aluminum and some die-cast alloys can be colored by an anodizing process.
- In your PSU interconnects, keep Pin 1 as the return/common/shield/chassis/ground/ connection. At the very least, this will prevent an exposed chassis (or shield) from being elevated to some supply voltage. (And make sure you know which pin is truly "Pin 1". The pin picture gets flipped around between male and female, and whether you're looking from the cable side of the connector, or the mating side.)
From a technical point of view, there probably wouldn't be any problem with using XLR plugs for connecting +/- 15 V rails, however, I strongly agree with dchisholm. Chances of mistaking one in- or output for the other are always present.
There will be other options that look as neat as XLR-plugs, perhaps even better as XLR-plugs are rather bulky. For example this DAC with power supply in a separate chassis. These are connected using nice, compact and very neat looking connectors (IMHO).
There will be other options that look as neat as XLR-plugs, perhaps even better as XLR-plugs are rather bulky. For example this DAC with power supply in a separate chassis. These are connected using nice, compact and very neat looking connectors (IMHO).
If you are set on using the XLR style connector, I would suggest using the 4 pin connector. This would prevent any accidental connecting to the units. The 4 pins are usually available from your normal sources such as Mouser, Parts Express, etc.
From a technical point of view, there probably wouldn't be any problem with using XLR plugs for connecting +/- 15 V rails, however, I strongly agree with dchisholm. Chances of mistaking one in- or output for the other are always present.
There will be other options that look as neat as XLR-plugs, perhaps even better as XLR-plugs are rather bulky. For example this DAC with power supply in a separate chassis. These are connected using nice, compact and very neat looking connectors (IMHO).
Yes they do look good but I wonder about availablity and price. I think I will either use 4 pin XLR or mark them "loudly". I am the only one that operates my stereo equipment so I am not overly concerned about incorrect connecting. But the possibility does exist.
Thanks for the replies 😀
These are sweet and come as a chassis plug for the power in. See RS. Farnel, Mouser etc etc etc.
convertCON - Neutrik
convertCON - Neutrik
For power supplies these ones are generally used
Connecteur aviation XS12 K3P verouillable par encliquetage 3 ples 250V 3A 7mm - Audiophonics
connecteur micro multicontact mle 4 broches 14.2mm
embase din mle 6 broches 21.5mm
Connecteur aviation XS12 K3P verouillable par encliquetage 3 ples 250V 3A 7mm - Audiophonics
connecteur micro multicontact mle 4 broches 14.2mm
embase din mle 6 broches 21.5mm
There are 4- and 5-pin versions of the XLR, and possibly even a 6-pin. Using the higher pin count addresses the problem of accidental connections to common audio signal lines. While these variations aren't exactly rare, you're unlikely to find them at your local music store when your project comes up short by one plug on a Friday evening.
Check the connectors' current and voltage ratings - as I recall, the original XLR-3 was rated for 5 or possibly even 10 amps, but the smaller pins in XLR-4 and XLR-5 may be good for only an amp or two.
Dale
I had a closer look at the chassis and cable parts of those connectors (I have that DAC), unfortunately, they weren't marked. They look nice from a distance, and they do their job, but close up, they didn't look like industrial quality, though (but not as cheap as Chinese knock offs). I'd say they would cost only slightly more than the parts clsidxxl linked to, so possibly cheaper than XLR.
They seem to be some kind of aviation connector with a locking mechanism instead of a screw type connector.
At work, I work on equipment with Hummel and Lemo connectors, they are a whole lot better looking (quality) and a whole lot more expensive.
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Unusually the Signal XLR uses male for output and uses female for input.
Power from the Mains ALWAYS uses female for output. We expect that and have come to think of it as "standard". One can't touch the Hot pins.
If you use 3 pin XLR for power, you could revert to the "standard" female for output power. Then your Signal XLR cannot be interconnected incorrectly.
Power from the Mains ALWAYS uses female for output. We expect that and have come to think of it as "standard". One can't touch the Hot pins.
If you use 3 pin XLR for power, you could revert to the "standard" female for output power. Then your Signal XLR cannot be interconnected incorrectly.
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