Audio Splitters

[Davetherave]

can anyone tell me if theres any 19" rack mountable audio splitters in the shops.

what i need is something with 1 L/R input with 4/5 L/R mono outputs with individaul level controls if that makes sense.

[General Lighting]

normally you have to buy that sort of thing and make it / wire it up yourself.

I think you can buy the pre-drilled panels and put the XLRs or whatever else in them.

what sort of connectors are you planning to use?

TBH I would think that commoning all those audio feeds would cause a impedance mismatch at some point and affect your sound quality. The "correct" way to do this is to use something called a distribution amplifier but they are expensive.

what exactly are you trying to do here? just power a load of amps off the same sound source? There may be better ways of doing this.

Maplins in Ipswich may have some of the bits you want, Professional Audio and Video Equipment - Canford Online (http://www.canford.co.uk) has better (and more expensive) stuff

[Davetherave]

basicly ive got five pa amps and i want to some how link them up from one output. but i aint shure how to do it.

[General Lighting]

what are the makes and models of these amps, and what sort of inputs/outputs do they have? i

(I'll also move this into the tech section, you may get an automated message, although it has my name on it it is from a robot :wink:)

[Davetherave]

they are kam and W-audio amps all with L/R 1/4" jack inputs and speakon outputs.

[General Lighting]

are there two sets of jack inputs? (don't get confused with speaker level outputs here!)

if so you may be able to just daisychain the inputs, particularly if the W-audio's phono and jack input sockets are commoned, and the KAM amps have two sets of input sockets, then you could use standard instrument patch leads.

if not you might as well get out the soldering iron, buy the plugs and cable from Maplins and make a "bodge" lead with the connectors hardwired.

Make sure you get the inner and outer parts of the jacks all wired correctly though, and slide the barrel of the jack on before you do the soldering to avoid a lot of cursing and swearing when you realise you have forgot.

Neither of these methods are the "top quality" way of doing it (I can see Biotech, Raj and the other "proper" sound engineers wincing at the very thought of this rum plan!) but it will allow you to use what you've got.

I did look for "multi way splitters" but couldn't find any and TBH I wouldn't spend too much on bits doing it this way for too long, as you can probably pick up a crossover a lot cheaper these days from a crew which is upgrading or standing down..

if you do it by just feeding multiple full range audio you may find it better to use both your main and record outputs of the mixer and then you can have two separate audio feeds to the amps.

It will be very important your DJ's dont' redline the mixer!

[BioTech]

I haven't got a lot a time at this moment and haven't read the thread properly yet, but you can't really go wrong with a Behringer Ultralink pro.

Behringer are usually best avoided but this bit of kit does the job nicely and wont break the bank. If you want anything better you will have to expect to pay more than double the price and for what it does it's not necessarily worth it for smaller systems.

It has a 1 stereo in XLR or Jack, 1 Stereo out and then 6 (I think) mono outputs which all have seperate gain control. You can also flick it round so it acts as a mixer, eg 6 in 1 out.

MIXERS / POWERED MIXERS - ANALOG MIXERS - ULTRALINK PRO MX882 : 8-Channel Splitter/Mixer ? Level Conditioner/Converter (http://www.behringer.com/EN/Products/MX882.aspx)

I think they are about £70. Can't remember.

[General Lighting]

thats a good price for what you're getting and would certainly help Dave and his crew out (and be useful even when they do eventually get a crossover)

[Davetherave]

cheers biotech, thats the type of thing im looking for and its cheep aswell.

[General Lighting]

yep, you wouldn't be able to buy the components for that price...

The link takes you to a place where you can download the manual and work out how its wired up before even buying it, so you know what leads etc to get...

[BioTech]

No problem. GL's suggestion (now that I've had time to read it) would be fine also apart from the obvious lack of gain control which you specified.

I'm not totally sure on the voltage drop and impedance fluctuation when splitting a signal multiple times but I seem to remember you can get away with splitting a signal 4 times before you may start to run in to issues.

Don't quote me on that though, as it's something I've never done or looked in to and my electrical knowledge isn't as good as it should be so I can't work out the math behind it.

[Subvertech]

I agree with Biotech. I use a Behringer Ultralink and its a good peice of kit.

[noname]

Strikes me that what you're looking for is a decent mixer - most engineer mixers (as opposed to DJ ones) will have at the very minimum a set of auxilliary bus outputs that you can use to feed signal to amplifiers, and probably a set of subgroup faders with corresponding subgroup outs - giving you control over the levels being sent to the amps...

You can also generally daisychain amps together - most amps have 2 sockets marked as inputs on each channel - basically giving you the ability to parallel feed them all from one input (so your signal feed goes into the first pair of sockets, and the second pair of sockets are connected to the next amps inputs, and so on down the line...) Because they are connected in parallel, the voltage across the whole chain of inputs doesn't change - the full voltage is available to all of them.

As for the load impedance - thats a bit more complex, and involves having the values for both the source Z (impedance on the output of the device providing the signal to the amplifiers which can be anything from 50 Ohms to 2K Ohms), and the input impedance on the amplifiers (typically 20K Ohms). In order to transfer the signal without introducing major deviations in level and frequency response, the Source Z to Load Z should have a ratio of at least 10:1, so the combined input impedance of all the amplifiers has to be equal to or greater than 10X the impedance of the source device...

So SourceZ X 10 <= loadZ (the total impedance of all amp inputs).

If your amplifiers have differing input impedances you need to find the average for them - so add the impedance values and then divide by the number of amps (so if you have 1 amp @ 18,000ohm, 1 @ 15,000ohm and 2 at 20,000 you would do (18000+15000+20000+20000)/4 = 18,250, and 18,250/4 = 4562.5 - this would be your loadZ and the value that the sourceZ X 10 mustn't exceed. Most amps are 20Kohm though, so usually you won't need to bother doing this, and would just use 20,000/number of amps as your loadZ.


So, to find the number of amps that can be paralleled from a signal, you divide the average amp inputZ (or loadZ X number of amps) by the sourceZ and then divide by 10

Example: Your mixer output has an impedance of 330ohms (the sourceZ), and your average amplifier input impedance is calculated at 20,000ohms.

So 20,000/330 = 60.6060 and then 60.6060/10 = 6.06 (which rounding down to the nearest whole because you can't get .06 of a power amp... In this situation you could parallel 6 amplifiers to that source without running into problems - in practice it's better to err on the side of caution, because this is a simplified calculation, so you would take 1 off to be safe and not connect more than 5 amplifiers).

Obviously this means that the lower the impedance on the signal source device, the more amplifiers can generally be driven from it...


Hope that makes some sort of sense... If not, Peavey US have a very good tech paper on impedances in audio systems which can be found here: Peavey.com :: Impedance in Audio Technology (http://www.peavey.com/support/technotes/concepts/impedance.cfm) (A quite fascinating read if you're into this sort of thing :crazy_fre: )

:crazy_diz:crazy_diz:crazy_diz

[SingularLattice]

TBH I would think that commoning all those audio feeds would cause a impedance mismatch at some point and affect your sound quality

Pull me up if I've misread the problem (I'm skim reading at best), but I thought impedence 'matching', and all the horrible matching transformers and the like went out with vacuum tubes. It is far more conventional to have a huge impedence difference between inputs and outputs (usually at least ohms->kohms). Think about it: if you have one very low impedence in parallel with several high impedences, who gives a shit how many high impedences you have?

If I were worried, I'd just break out a bit of breadboard and solder together a few op-amps and do some unity gain buffering.

[General Lighting]

Pull me up if I've misread the problem (I'm skim reading at best), but I thought impedence 'matching', and all the horrible matching transformers and the like went out with vacuum tubes. It is far more conventional to have a huge impedence difference between inputs and outputs (usually at least ohms->kohms). Think about it: if you have one very low impedence in parallel with several high impedences, who gives a shit how many high impedences you have?


this is true, but the young lad who started the thread was using a mixture of low end audio amps for which the proper specifications weren't the easiest of things to obtain (and often inaccurate/badly translated)..

matching transformers were still used by the BBC well into the 21st century - certainly when I was working in pro audio for broadcast - they were built into the mixers and had to be specially imported from Sweden (this surprised me too!)


If I were worried, I'd just break out a bit of breadboard and solder together a few op-amps and do some unity gain buffering.

this is what the behringer kit basically is - but as I mentioned earlier they seem to be selling it for less than the cost of the components.

[SingularLattice]

matching transformers were still used by the BBC well into the 21st century - certainly when I was working in pro audio for broadcast - they were built into the mixers and had to be specially imported from Sweden (this surprised me too!)

Certainly are, but not for this type of application. One guy i work with previously worked for a major quality matching transformer manufacturer. He gave me quite a few helpful hints for one of my recent research projects.

I can't go into fine detail; the papers have not yet been published and we've yet to put the IP in place. I built a massively powerful amplifier for deep sea use. Very low frequency, fidelity was an issue, so I had to go with a class AB design. I needed to drive a 100 microohm load with as much current as possible. In the end, I custom wound my own transformer. Worked beautifully. Had a hell of a lot of fun carrying out the experiments!

[General Lighting]

In the case of Auntie there are (or were) still a fair few traditionalists there and as late as 2000/01 many studios still used a significant amount of analogue kit.

as for the the lad making the original post I got the impression he is part of a fairly young crew (aged in their late teens to early 20s) - who live in the same area as me and are just starting out . At this stage they are better off using off the shelf equipment and easily available items until they gain the knowledge on how to do more custom stuff...

The poor sound quality of East Anglian free party crews (apart from three of the "older" ones) was a standing joke for many years (until zero tolerance stopped the bulk of the raves anyway).

But from what I've seen in recent times it wasn't due to poor quality equipment or lack of funds - its simply due to a combination of dumbing down and ketamine (the two being linked) - lots of people actually have fairly decent kit but don't know how to use it.

Sadly there aren't many opportunities to put on events here any more, with only three venues in a whole county tolerating dance music events...

[SingularLattice]

apart from three of the "older" ones

Which were they then?

I remember Pulse-8 being good, but that's going back 8 years or so now

[damo666]

Which were they then?

I remember Pulse-8 being good, but that's going back 8 years or so now

The pulse 8 parties were topraaa.