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The best way to connect two sub/satellite systems in tandem.


Peter Basey

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Greetings Blue roomers

 

I'm hoping somebody will be able to help me cable up my new toy! I've just bought a DAP Soundmate 1 (HK clone) via fleabay and I already own a LEM Cyclops (Similar sub/two satellites set up)

 

For bigger gigs I want to use the two systems in tandem,utilising all four satellites, but I'm not sure of the best way to connect them to my mixer with minimum cable runs. I'm thinking a Y splitter lead in the back of each sub and a single XLR lead from each side of the mixer would be the easiest option but don't want to blow anything up!

 

Or a Y splitter at the mixer end and two XLR leads to each sub? Or both mixer sends to left and right of the DAP and then send 2 leads from the through outputs left and right.

 

I hope somebody can let me know the safest way of doing this with minimum cabling as it's all one nighters and every lead means extra time setting up and breaking down as you'll all appreciate!

 

Thanks

Peter

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I suppose it all depends on your speaker placement, though the DAP Soundmate 1 mkII has XLR out on L+R channels, so linking through may be simpler than adding Y splits.

 

Do you envisage one of each mid/high per side? and the subs together, or split?

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Well I was planning on putting the Lem sub/sats on one side and the Dap on the other. The only thing about using Y splits is that I could balance out the volume each side more easily than routing one set through the other, and I think I'd get a better stereo image. It's mainly for live sound with a bit of a disco in the breaks.
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What was it that made you buy a different system rather than more of what you already had? It really can make things difficult. I don't want to spoilt the show or anything, but whilst you'll get a "useable" sound out of something you are increasing the chances or more problems.

The comb filtering is one of them depending on how you arrange the cabs, without looking I suspect that both are 90 degree boxes. Providing this dispersion is stable down to a reasonable frequency you'd need quite a wide splay angle on this to minimise comb filtering. Then you have the problem of the boxes sounding different. Different people in the room will get a different sound anyway, lets not make this worse.

 

Dependant on the design of the subs, this may have phase issues, this also depends on the crossover and other processing within them. This can lead to a very uneven response.

 

If you minimise the gap between boxes (ie point them the same way) you'll get an increase in volume and minimise comb filtering a little as the time offset will be minimised. however if they are different boxes, this will give a different sound and again this will create an uneven response.

 

 

Rob

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I have no particular experience with this, however it could concievably help you...

 

if you treat the two systems as two separate systems in their own right (mixing one off of auxes??) then you could utilise one for vocals and one for instruments for example. Dave Rat did this with two V-Dosc systems for the chilli peppers if I remember rightly.

 

This would avoid the phase cancelation issues that would otherwise worsen the quality, however it would not work for your disco application.

 

I realise that this will be more wiring and set-up intensive; just popped into my head as how to get the best out of your set-up

 

those more experienced feel free to shoot down in flames :wall:

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What was it that made me buy a different system? Impulse, and the fact that it was £200 which seemed pretty reasonable. I could always stick one of them back on ebay if I could find a match and make a pair. I've been using the Lem on it's own for some time and been pretty pleased, but the Dap seems (so far) to have a lot more middle, so I'm hoping between the two I'll fill all the frequencies! If not - anyone want a Lem Cyclops? BTW I have NO idea what comb filtering is, but it sounds too technical for a mere PA owning singer!
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Each frequency has a wavelength. The higher the frequency the shorter the wavelength. One fully cycle is 360degrees half of this is 180degrees where the signal is the opposite polarity the original signal. In this case as there is a shift in time this is known as being 180degrees out of phase. Or reversed Phase.

 

When you have 2 speaker sources and you stand at a given position, the sound from one speaker arrives at a different time to the same sound from the next speaker. this is a time offset. Dependant on that time offset will depend on the wavelength (or half wavelength) that is effected. The frequency effected will completely cancel (such as +10 and -10 equal 0). There are other frequencies where the wavelength will be 360degrees out. At this point the signal will combine and become louder at this frequency.

This means that a number of frequencies will disappear, and a number of frequencies will be boosted. This is different dependant on where you stand. If you look at the signal it creates it is a series of points (which look a bit like the teeth on a comb). This is of course a problem. You can minimise the effect by having both speakers pointing exactly the same way but this does not remove the problem entirely. If both speakers also sound different then you introduce even more problems into the equation.

 

I think you have a number of options.

Firstly, try it, you may find it works well enough for the things you need it for and that way you'd got yourself a good deal.

 

One option is to sell one system (you may make a profit) and look for a system the same as the one you keep, though the same comb filter rules still apply.

 

Another option would be to sell both systems and buy a larger complete system. Though I realise that this may require some additional financial input and also it may be too much for smaller venues you do.

 

 

Rob

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Thanks for explaining that Rob.

I'll give it a trial run and see what happens. Selling off the Lem did occur to me if I can get another DAP system (or vice versa). I can't really afford to buy a bigger system and as you say it would't be suitable for smaller venues (which is mostly what we do at present) I don't really visualise using both together more than a dozen times a year at the moment.

Peter

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I don't really visualise using both together more than a dozen times a year at the moment.

 

In which case have you thought about hiring for those dozen gigs. It would of course depend on the budget available. This could be hiring a full system. or hiring additional boxes of what you have providing they are used correctly.

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Well we have hired but for a £200 investment it means we wouldn't have to. About the cost of one hire really. Anything these wouldn't cover there's usually a rig supplied anyway, ie Jive weekenders. And I looked for somewhere I could just hire a couple of big active Mackies or similar and couldn't find anywhere near enough to be practical.
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