A really stupid question

[Benny Smyth]

Recently, I had had an issue with my primary playout. First time in 18 years, but it's made me ponder about what to do going forward.

As is standard, I have two laptops that are exact mirror images of each other - both have Traktor with updated library and both have MyDMX. Every night, one will run MyDMX and the other Traktor. I have two S4 Kontrollers set up so should option A fail me, then I move over to option B. The problem is that I don't use a mixer to plug into, so for the one issue I've had, I had to pull the output from one S4 to the other. Took mere seconds, but it felt like a millennia!

I'm not a fan of having a mixer as it'll add another minute or so to my setup and takedown (and if you're thinking "So what?", then you're not like me who spends ages working out how to shave seconds here and there), plus the sort of person that I am will have a Xone:43 (http://www.511virginia.org/?lat1=39.28&lon1=-83.41&lat2=36.32&lon2=-75.15) or something of a similar ilk.

So, to avoid the extra expense of a mixer, can anyone tell me why having an XLR splitter (https://cpc.farnell.com/pulse/pls00200/lead-xlr-plug-to-2x-xlr-skts-3m/dp/AV19127?mckv=sYpxKc03K_dc|pcrid|224645200689|kword ||match||plid||slid||product|AV19127|pgrid|5387637 6704|ptaid|pla-393650414874|&CMP=KNC-GUK-CPC-SHOPPING&gclid=EAIaIQobChMIipnfiLuA3QIV75ztCh1GRgQ6EAQYASAB EgKep_D_BwE) plugged into the speaker, with both the primary and secondary playouts plugged in wouldn't work?

To me, it looks like it would do the job but I just want to make sure that I'm not overlooking something.

[Excalibur]

Well the short answer is because you're not splitting, you're joining. :p And yes, I know I'm splitting ( hairs ) but behind the whimsy, there's the reason.

Splitter cables are simple ones, but joiners should have resistors in to ensure safety, as you may damage one component, but I'm not well enough up on it to say what size of resistor or other component. We've had this discussion elsewhere, on another forum. Not to say I haven't done something similar myself without problems, but just because I got away with it, doesn't mean you will.

Hopefully, the technocrats will be along shortly to explain. What would I recommend? Well the easiest one would be a switching box, which is exactly what its name implies. Problem with that would be the almighty thump through the PA as you press the switches.

Top of my head, nothing springs to mind. Mixer isn't the best option, simply because it's duplication of components. Sorry I haven't helped much.

[funkymook]

It might be stating the obvious but if your speakers have a second input just have another run of xlr cables going into that from your back-up.

[Imagine]

It might be stating the obvious but if your speakers have a second input just have another run of xlr cables going into that from your back-up.

^^^ What he said, although it increases set up time.

I used to worry like that (there's a post on here somewhere about it and indeed I did purchase a splitter thingy....which actually had the effect of dampening the signal somehow).

I still carry spares of everything, but I'm not that paranoid these days. If there's 30 seconds of dead air then so-be-it. I have the backup and knowhow to get out of it and the party will continue.

Not ideal, but talking to several other operators in these here parts recently who I thought worked in the same sort of way as me....if something of theirs dies (including laptop or mixer) - the party's effectively over! They can't afford/don't want to store the spare kit :o

Now THAT is a way I'd NEVER feel comfortable working with.

[Nakatomi]

Blah blah output impedance blah blah input impedance..

Or in laymans terms...

Ye cannae just combine mixer outputs into one cap'n or she's gonna blow.

Better to use a passive or active combiner/mixer. With passive yay no power needed & very little can go wrong but... You lose some signal level.

Active combiners/mixers won't incur any signal loss (ideally) but need power.. And then they're just another thing that can go wrong.

For my money I'd prefer to take the hit of a few seconds of dead air when something goes wrong than increased setup & teardown time.

[Nakatomi]

The technical explanation of why you shouldn't just combine the outputs of audio devices is this :

The output impedance of a mixer or other playout device is generally quite low, say around 150 ohms. This is designed to plug into an input which might have an input impedance (in most pro kit) of around 600 ohms or 1000 ohms or more.

Plugging one output into another, you're potentially halving its drive capability (voltage level and headroom before distortion) because 150 ohms in parallel with 150 ohms is 75 ohms. This would mean the output stage of each device would have to work twice as hard as usual. They may cope, or they may not. They may be damaged but best case performance will likely suffer.

Passive (unpowered) combiners will use either transformers (slightly lossy but expensive ) or resistors in line to sum the signals (more lossy but much cheaper & less bulky than transformers).

Some kit, it's unknown which, you can likely get away with joining outputs of til the cows come home. That's usually real pro stuff like what they use in radio & telly though (where it's still analogue signals anyway). I remember reading sonifex cart machines' outputs were designed to be connected across others so a cart machine stack would only need one stereo pair of mixer inputs.

[funkymook]

The technical explanation of why you shouldn't just combine the outputs of audio devices is this :

The output impedance of a mixer or other playout device is generally quite low, say around 150 ohms. This is designed to plug into an input which might have an input impedance (in most pro kit) of around 600 ohms or 1000 ohms or more.

Plugging one output into another, you're potentially halving its drive capability (voltage level and headroom before distortion) because 150 ohms in parallel with 150 ohms is 75 ohms. This would mean the output stage of each device would have to work twice as hard as usual. They may cope, or they may not. They may be damaged but best case performance will likely suffer.

Passive (unpowered) combiners will use either transformers (slightly lossy but expensive ) or resistors in line to sum the signals (more lossy but much cheaper & less bulky than transformers).

Some kit, it's unknown which, you can likely get away with joining outputs of til the cows come home. That's usually real pro stuff like what they use in radio & telly though (where it's still analogue signals anyway). I remember reading sonifex cart machines' outputs were designed to be connected across others so a cart machine stack would only need one stereo pair of mixer inputs.

Does that still apply when only one output is being used at a time? That wouldn’t be summing two signals would it? (as would be the case if you have to switch to your back-up).

[ppentertainments]

I still carry spares of everything, but I'm not that paranoid these days. If there's 30 seconds of dead air then so-be-it. I have the backup and knowhow to get out of it and the party will continue.


I am the same now after many years of having secondary playout etc all wired in ready to go.
Nowadays I have backup mixer etc in the van, second laptop in a case with me. Should there be a bit silence I am sure nobody is REALLY going to complain if you explain the situation and get up and running with minimal fuss.

[funkymook]

I am the same now after many years of having secondary playout etc all wired in ready to go.
Nowadays I have backup mixer etc in the van, second laptop in a case with me. Should there be a bit silence I am sure nobody is REALLY going to complain if you explain the situation and get up and running with minimal fuss.

Unless it’s the first dance or other key moment...

[Nakatomi]

Does that still apply when only one output is being used at a time? That wouldn’t be summing two signals would it? (as would be the case if you have to switch to your back-up).

If one is powered off, then maybe not but it depends on the makeup of its guts. Otherwise yes.

[ppentertainments]

Unless it’s the first dance or other key moment...
Ceremony and first dance I have an immediate system in place, for the rest of the night I don't.

[yourdj]

Unless it’s the first dance or other key moment...


Ceremony and first dance I have an immediate system in place, for the rest of the night I don't.

Quite. I have an iPad using DJay to get me through a few tracks and a laptop/controller in the car. No one would know any different even during first dance but it if I pressed play on both at the same time, it would be seamless. It would take a few seconds to set up the new system. i might start thinking about having the controller next to my main kit, although its more probable that the laptop will go down. :)

Can you not go through the dead controller Aux if it works as a separate input/output when not on? My VCI 300 did that so I would be surprised if its not standard these days (my mc4000 does it i think). Mixers don't take that long and are dead handy for a bit of extra gain and other connections if required. I have a small mackie mixer in box that is already all wired and loomed up with the electrics and lighting control, so thats possibly worth a thought as it save LOADS of time setting up. Perhaps a mixer can be incorporated into your controller flight case?

18659

[DJ Jules]

Combining signals without a mixer is a big no-no (or is, at best, likely to create problems), switching between them is fine. I've had recent experience of a bar where they've split the output to run an amp for a pair of speakers on the dance floor and a secondary system that repeats the sound using small speakers around the bar by daisy chaining the signal through the in/out connections on a set of small amps. It all works fine unless one of the amps is turned off. With any one of the amps turned off you get a weird repeated popping noise come through all of the remaining amps/speakers as capacitors in the input stages of the powered down amp charge and discharge!

Keeping it simple, maybe the answer is to reduce the amount of time it takes to change the cables over using a balanced switch?

E.g. http://www.goldpt.com/sw2x.html or https://www.thomann.de/gb/kramer_vs_4x_passive_stereo_switch.htm

Julian

[funkymook]

Ceremony and first dance I have an immediate system in place, for the rest of the night I don't.

Fair enough, though I’d have thought if you’re going to the trouble of having back-up for the first dance then it can’t be much more hassle to have back-up for the rest of the night in place as well.

[Benny Smyth]

Thanks for the input, guys. Just as well I asked before going ahead with it!

[yourdj]

I don't have a clue what i am talking about, but though of this on the way home tonight. Its a stupid question to compliment a stupid question. :)

If you have 4 XLR's 2 of which are in the main playout and 2 in the backup (and two further XLR's going to the speaker), as long as you are not playing sound though both at the same time then would it not matter as there would be no conflicting frequencies or what ever, or it still be a problem??

Like this for one side

18660

[Excalibur]

I don't have a clue what i am talking about, but though of this on the way home tonight. Its a stupid question to compliment a stupid question. :)

If you have 4 XLR's 2 of which are in the main playout and 2 in the backup (and two further XLR's going to the speaker), as long as you are not playing sound though both at the same time then would it not matter as there would be no conflicting frequencies or what ever, or it still be a problem??

Like this for one side



As explained above , Toby: Depends. Do ya feel lucky? :confused:

With some combinations, no probs. With others, disaster. Do ya still feel lucky?


Benny, re your question, and following on from suggestions from Martin, and a discussion with a colleague: Had you opted for a Maui rig, rather than your FBT, it would have been possible to use the mixing facilities on speaker one to accept each controller simultaneously, and feed this out to speaker two.

However, extrapolating the " what if " scenario further, should speaker one fail.............................................. :bang:

[mike8863]

Can I ask a silly question please, sort of related......
How many active tops can you daisy chain via xlr before losing sound quality or causing any damage ?
Regards

[Nakatomi]

Simple answer : quite a few.

Be careful of creating ground loops though, especially if speakers you put on the line level chain are powered from different mains wall outlets.

The question here is, why do need to team up stacks of speakers? Wouldn't it be better to acquire or hire something bigger?

See, you can only get so much out of putting speakers next to one another. Especially if they're not the same make & model. Placement becomes an issue.. Put 2 mid/top speakers side by side & you can end up with some parts of the audio spectrum cancelling each other out resulting in a weird, hollow sound.

[Excalibur]

The question here is, why do need to team up stacks of speakers? Wouldn't it be better to acquire or hire something bigger?


Mayhap he would like to extend the music into an adjacent room or rooms? :confused:

[mike8863]

spot on Excalibur , it's for a pub gig on nye, they have numerous rooms , and want music in two of them !

[Nakatomi]

spot on Excalibur , it's for a pub gig on nye, they have numerous rooms , and want music in two of them !

Well then that shouldn't be a problem so long as the power for both rooms is on the same mains phase. If it's not... Things could get nasty. Same if there are differences in earth potential between rooms. You may find you need to lift the AUDIO ground connection to stop hum. Note the capitalised AUDIO there. Never EVER disconnect a mains earth connection.

[yourdj]

I can't actually answer your question, but I have run into a few speakers in the past with no noticeable difference.

A digital audio sender might be your friend here? It will look better and will not cause any obstructions etc. These are reasonably expensive, but you can get them very cheap these days? If you have a lapel mic system you can use it the opposite way round and plug the lapel into the mixer output and have the box (receiver) where the speaker is. I do this a lot when MCing weddings as i can then control the music from floor level and have the speaker in the gallery. I believe it runs in Mono on my system though, which is not that noticeable?? Its never failed.

Having said that in many circumstances (especially an event as big as NYE) you might want to limit and technical failures and a cable is always the best option. :)

18686

[mike8863]

thankyou all for your assistance.

[khards]

I would hope the likelyhood of one system failing is such a rare event that a even 30 second delay in the entertainment is passable. I guess the problem is that your mic would also fail for the duration as you must have it plugged into your controller.
I take a different aproach that is a backup laptop & controller that isn't setup and under the linklely event things should go wrong during the gig (customer spilling a pint over the laptop etc.) then I can boot up the spare laptop in under 60 seconds.
I have a small mixer I use for the controller output, wireless mic's and my wired mic.

[ckpr2]

Because the both sources are driven probably by an operational amplifier then that output is low impedance (or nearly a short).
So connecting two together will just short each other out.

You would need to disconnect the faulty output from the amp connect the other output to make it work again.
Or as others have said use two separate inputs on the speakers.