Need a certain output jack.

[40Hz]

Yes, they did. But I didn't want weird plugs and cables. I wanted virtually any bass to run with remote power and no batteries. Yet, I also wanted to
to be able to switch back to batteries in an emergencY! The usual Use of ring as a switch does this since all you do is short the battery clip and then
Feed power in the ring line of a TRS cable works great (except when power circuits are isolated!)

You might want to look into what's called a power injector such as gets used for PoE or "power over ethernet" cabling. We've used it in the IT world for many years. It basically commandeers two wire pairs in a CAT-5 or CAT-6 cable to send low voltages down the line to power the device at the end of the network cable. Handy for putting wireless acess points (WAPs) in optimal locations where an AC outlet isn't available. You could probably easily adapt that concept to instrument use.

However, I can't see any way to push audio and power over the same cable run without two pairs of wire. So the cable is going to be heavier and possibly stiffer than standard audio cable no matter what you do, or what connectors you choose. A heavier cable is also easier to pull out so a locking mechanism is preferable.

Other problem is, if you're putting power through rings in the same jack, there's a chance of briefly shorting the power into the audio signal path of the circuit when you plug or unplug. So there's a chance that 9 or 18 volts is going to hit the input jack of the amp, or something in the signal path of the onboard preamp, which probably won't like it very much should it happen. The DIN connector keeps all the leads separated and isolated from each other so that prevents that issue from happening.

 

[bassbenj]

You might want to look into what's called a power injector such as gets used for PoE or "power over ethernet" cabling. We've used it in the IT world for many years. It basically commandeers two wire pairs in a CAT-5 or CAT-6 cable to send low voltages down the line to power the device at the end of the network cable. Handy for putting wireless acess points (WAPs) in optimal locations where an AC outlet isn't available. You could probably easily adapt that concept to instrument use.

However, I can't see any way to push audio and power over the same cable run without two pairs of wire. So the cable is going to be heavier and possibly stiffer than standard audio cable no matter what you do, or what connectors you choose. A heavier cable is also easier to pull out so a locking mechanism is preferable.

Other problem is, if you're putting power through rings in the same jack, there's a chance of briefly shorting the power into the audio signal path of the circuit when you plug or unplug. So there's a chance that 9 or 18 volts is going to hit the input jack of the amp, or something in the signal path of the onboard preamp, which probably won't like it very much should it happen. The DIN connector keeps all the leads separated and isolated from each other so that prevents that issue from happening.

Yes, shorting is a problem. However i just use "one spot" pedal wall warts and they work fine, They are totally short protected so there is not a problem (note that shorting can occur if you plug a standard cable into the amp equipped with power as it shorts the ring if the power is turned on (there is a power on-off switch). The beauty of the system is that Commercial TRS cables are widely available and are nice and flexible, shielded for audio and work great. No weird plugs or jacks needed. The TRS cables are not especially heavier than standard cables. By the way I have a bass with a locking connector (for standard cable) It seems like a great idea but in practice I find it to be sort of a pain. It's hard to pull the plug out while at the same time pressing the unlocker with just one hand.

To keep the 9 volts out of the signal path, it's best if you plug the amp side first and then plug the bass side last. I have used this for a long time and really have never had any damage from wrong plugging. So yeah, a special connector and cable is best from a technical standpoint, as usual tradition rears it's ugly head which is why those silly phone plugs are still being used, and in fact as the defacto standard it why I stuck with them.

One day I may build a special bass with a special plug and cable which would be something like a 5 pin XLR with low impedance to the amp like a mic etc. But the down side is it's all very special and you can;t use anyone else's amp, cables, bass, or whatever. It will all be special.