I’ve been doing a bit of audio work recently (working on a community radio station) and one thing that kept recurring was the need for audio a diverse range of cable adaptors; 3.5mm male stereo jack to male phono pair one moment, XLR female pair to 6.5mm male stereo jack the next, and so on. Sometimes this meant ‘chaining’ a bunch of different cables and adaptors, which I don’t really like doing. On occasion, we simply didn’t have the right adaptors to make the link.
I started thinking… since I only ever want one of these sort of adaptors at any one moment (typically when I’m trying to port something from one system to another, or capture an audio signal), why not make a universal audio adaptor?, so it would consist of nothing much more than a junction box with a load of shielded flying leads, terminated with:
2.5mm male and female stereo jacks
3.5mm male and female stereo jacks
3.5mm male and female mono jack pairs
6.5mm male and female stereo jacks
6.5mm male and female mono jack pairs
male and female phono pairs
male and female XLR pairs
All connected to a common bus inside the box.
I can’t see any immediate reasons that this wouldn’t work other than:
-It would make it a little easier to make inappropriate interconnections
-The unused trailing connectors might short each other (perhaps this could be largely overcome by plugging the unused males into the unused females, although I’m not sure this would actually work in all cases, like the XLR)
Does something like this already exist, or is there just no reason to do it?
The first problem I can see is if you hard wire it all together then a stereo pair connected to a mono plug will turn any stereo signal into mono even if you aren’t using that connector. I thik it will be prone to a lot of noise and interference.
There’s no mixing or splitting - all the mono would have to be in pairs - essentially any stereo signal in on any connector would be present as stereo on every other stereo connector, and as two mono channels on each mono pair; any single mono signal in would be present on the corresponding half of every mono pair and on half of every stereo connector.
That’s a possibility; I think using screened cables and plugging the unused connectors together would eliminate some of it.
The alternative is to make many different combinations of patch cable, or buy as many different versions of adaptor as possible and on some occasions use several of them together. My experience is that audio jack adaptors, even good quality ones, are rather susceptible to noise caused by mechanical movement.
IANAAT (audio technician), but I would think you’ll also run into impedance problems at the open terminators. As I understand it, incoming signals that aren’t passed into a device with the proper input impedance will reflect, not unlike sound waves bouncing off of a wall, and will therefore degrade your signal quality. You might be able to get around this by designing terminators for each output plug with the proper impedance, but then you’ll have to deal with a large number of tiny widgets instead of a large number of cables, and I don’t think there’s much economy of gadgets there.
IANAAT (audio technician), but I would think you’ll also run into impedance problems at the open ends. As I understand it, incoming signals that aren’t passed into a device with the proper input impedance will reflect, not unlike sound waves bouncing off of a wall, and will therefore degrade your signal quality. You might be able to get around this by designing terminators for each output plug with the proper impedance, but then you’ll have to deal with a large number of tiny widgets instead of a large number of cables, and I don’t think there’s much economy of gadgets there.
Actually, the chief engineer at a radio station I worked at built exactly that sort of thing. He made it work, but don’t underestimate your challenges. First off, there was a lot of signal loss, which meant adding an amplifier and power source. Secondly, because of the difference in impedence between the different cables and connections, it needed a lot of capacitors and internal wiring. The final box was roughly the size of a medium-size laser printer and AC powered.
Yup, the very worst I’ve had were male-jack to male-jack links. To make them work acceptably you had to sort of hold the plug in under tension with gaffer tape.
As an ex sound guy and home recordist I have all sorts of weird adaptors and odd-ended cables (some have transformers or attenuators). Which were aquired or made as the need arose. I think the problem with having a universal adaptor wouldn’t really work because there would always be a combination you hadn’t thought of.
I’d say you are better off making dedicated cables for the job at hand, you then don’t need to worry about the integrity of all the connections you’d have in a chain of adaptors. Or you could make one ended cables with the plug-to-be-connected on one end and a set of banana plugs on the other and connect through pairs of banana plug sockets like a sort of mini switchboard.
What MikeS says applies more to RF signals, audio doesn’t bounce off open cable ends like RF. But having a lot of open ends is asking for trouble with interference.
Although I’m sure your point still stands, kunilou, I should clarify that I’m not actually talking about a device that would be expected to convert the level or type of a signal - just join together two different connector formats, for example, the inputs on our studio mixing desk are all XLR pairs, regardless of whether they are expecting a mic input, line-level or whatever; one of our cd decks has a pair of XLR outputs and a pair of phonos, the other has a pair of phonos and a stereo jack, some of the computers have phono pair inputs, others have stereo jacks and so on.
All through the project, people would turn up in the studio with some audio device or other and we would want to either play out directly from their device or record their output into another device and we would have to cobble together some kind of cable-and-converter blend in order to do it.
This isn’t an issue at audio frequencies. A stub would need to be a significant fraction of a wavelength to be a problem, and the wavelength of audio, even at the upper end of 20 kHz, is about ten miles. As long as you keep those extra dangling cable ends less than a quarter mile or so you’ll be OK.
Been there done that. I was (mostly) a PA sound guy and a last resort was sometimes just to strip the cable ends and wrap the matching connectors together, secure cables together with a tie-wrap and insulate with gaffer tape. A classier variation might use a choc-block. A least in the studio you have the time to solder the connections. And I’d probably best not mention the “pokey wire” method.
This is a sound suggestion, but how about dispensing with the banana plugs and having:
2.5mm male stereo jack to male phono pair
3.5mm male stereo jack to male phono pair
3.5mm male mono jack pair to male phono pair
6.5mm male stereo jack to male phono pair
6.5mm male mono jack pair to male phono pair
male XLR pair to male phono pair
2.5mm female stereo jack to male phono pair
3.5mm female stereo jack to male phono pair
3.5mm female mono jack pair to male phono pair
6.5mm female stereo jack to male phono pair
6.5mm female mono jack pair to male phono pair
female XLR pair to male phono pair
phono couplers
the cables need only be quite short as they will either be used to connect two adjacent devices, or convert the termination of an existing longer cable. Trouble is that I’d need two of some or probably all cables, in case I want to set up a like-to-like connection. Hmph! Nothing is simple.
Piece of coat hangar wire stuck into a jack, and telephone wire wrapped around it and then wrapped on to the plug that wouldn’t fit the jack. Ground wire just wrapedd where it would fit. It worked amazingly well, especially considering that it was carrying a video signal.
hijack/
I used to work for an organization called the National Federation of Community Broadcasters, a membership organization of community-based public radio stations. We may know some of the same people.
/hijack
Am I reading your idea correctly here? You will wire each pair of connectors through this box to every ofther pair. The intent being that you can plug a signal into any of the pairs, and get it back out through any of the other pairs?
I’ll make a few comments assumung this is correct, and if my interpretation is wrong, please correct me.
First of all, forget about doing this as stereo pairs, do it mono and make two of them. A lot of public radio stuff is either recorded mono, or at least without any stereo effect that you need to worry about capturing.
And to replace the patch cords you would otherwise need, you’ll need a lot more than two of them.
Don’t ever use them as splitters.
I believe this is by necessity going to be an ungrounded system, so I suggest leaving out microphone level feeds and xlr connectors. The other reason I suggest this is that one of the boggest dangers in your model is plugging a line level output into a mic level input and blowing something out.
The size and bulk of the box presents some problems. Say two tape machines are on tables 5’ apart. You can’t just string two 2.5’ cables to the box and let the assembly hang free in the air. The weight will put strains on the connections that they won’t stand up to. So the box itself needs a little table space probably right next to one of the machines, and you need a 4’ and a 1’ cable – or some similar complication. You may end up needing to buy cables of proper length for the box and go :smack: .
Your best solution is what’s called a patch bay. The inputs and outputs of all your production units are wired to a box. In that box you establish “normal” routes, aka where the signal will flow by default. For instance, your mixing board output would be “normalled” to Recorder 1 and your studio monitor speakers. You can have an unpowered patchbay way you reroute or split signals by means of short cables, pretty much identical to phone switchboard cables, or powered systems that use electonic systems. If you’re dealing with fiber-optic signals, you pretty much have to go with an electronic system.
The disadvantage of patch bays is that you pretty much need a whole 'nother set of cables if you break up the gear to bring it to an event. You unplug the pieces and leave the cables, still routed to the patch bay, alone.
It’s been a few years since I had the “big box of tricks” with about 135 different adapters and cable stubs of the plug to gator clips type, but if you invert your thinking, I think this would be pretty simple and fairly compact.
Forget having a kajillion plugs hanging out of it and worrying that they’re going to short out left and right or find ground. Work with jacks. I’m envisioning a pair of RCA (phono) jacks wired up to a trio of phone jacks - a pair of mono phone jacks wired straight through to the phono jacks, and a stereo phone jack wired to both phono jacks.
But… your desk is all XLR inputs? What’s up with the phono plugs/jacks, then? Would it be simpler to just have some XLR-to-unbalanced phone jack transformer/adapters (the ones I’ve used were XLR to 1/4" (guess that’s your 6.5mm?) mono) and then have cables in whatever length is useful for you that are 1/4" mono plugs to whatever sort of other plugs? For the stereo plugs, you’d need to do the cable as a “Y” - stereo 3.5mm plug to the two 1/4" plugs, and label them left/right. Mono phone plugs would be just straight cables. (But what puts out stereo audio on a pair of mono 3.5mm jacks?)
Hmmm… we were broadcasting in stereo this year and a lot of our pre-recorded stuff was interviews that were recorded with a pair of mics (there wasn’t complete isolation of the channels, but there was a definite stereo effect).
I’m thinking now that the best route will just be to make up a bunch of straight-through cables for the most common/most likely configurations and make some other cables to adapt them to as many other combinations as possible.
I used to work in the Audio Visual lab at a large university. It always seemed like the two pieces of equipment you needed to connect never had compatible connectors.
We had a great big wall full of cables with various connector combinations, and a big box of adapters. That seemes to work pretty well.
