Some Questions

[ashrobinson]

Hi All,

 

I am fairly new to the production side of things, I know my way round a lighting board, can understand the concept of dimmers and cabling, know how to use a mixer and various other bits of normal kit, but there are some things I don't understand.

 

1. I need to order a Multicore+Stagebox, now im looking at some and it says like 24send and 8 return.

 

What do these numbers actually mean?

 

I have seen stageboxes etc but can't figure out what the send/return actually mean (apart from I guess sending signal to 24 devices and returning from 8? but cant figure out what would need to return).

 

unfortunately my speciality is IT, and they have put me in charge of our theatre (because its electrical, and computers use electric too <_<) which is fine cause im keen to learn.

 

2. Also I am looking for some XLR Leads and some jack-jack leads, not a problem but I can't seem to find anywhere if there is a max run per cable? or they signal boosting or anything, so just wondering on that front. Any recommendations on type to stop anhykind of interference?

 

3. We have in our Theatre, 2 Speakers, I would like to up this to 4 speakers (sound output all around room pointing at majority of audience).

 

now I have a 600w Amp, and its 300 per channel, so how can I hook this up to 4 speakers if there are only 2 outputs out the back of it? there a way of splitting cable so 1 output goes to 2 speakers? to I will have 2 left 2 right?

 

 

4 . Smoke machine for a small theatre, any reccomendations? would like a Hazer (low level smoke?)

 

5. Need to purchase a DI box for our laptop to stop annoying hum, suggestions?

 

APologies for all the questions. Just in case I Will post what we have.

 

1 x Alcora 24/48 Lighting Board

1 x Yamaha MG16 SOund Board

1x Stageline 600w Mixer (300 per channel)

2 x TOA speakers (old old old) 200w

3 x Shure SM58 Microphones

6 x Audio TEchnica 1600 Series Lapel Microhones

 

 

Cheers,

 

Ash

[Sound Man]

I have seen stageboxes etc but can't figure out what the send/return actually mean (apart from I guess sending signal to 24 devices and returning from 8? but cant figure out what would need to return).

 

You have guessed right, it's for 24 inputs to the desk and 8 outputs to the stage etc. You may need to use powered monitors on stage if any foldback was required so the returns could be used for this.

 

For your laptop, get a Behringer HD400 Hum Destroyer.

 

Hope that helps

 

David

[mark_s]

1. A multicore is generally used to avoid having to run shedloads of single cables between the mix position and the stage. The numbers simply mean how many of those single cables it can replace. For a snake with 24 sends and 8 returns, it means you can plug 24 instruments in at the stage end to go to the mixer, and 8 'things' in at the mixer end to go back to the stage. Returns could be used for things such as signal to amps, powered speakers/monitors, or similar. (Note I'm not a sound guy, so I apologise for any terminology mistakes!)

 

4. Haze, smoke, and low smoke are all different types of effects. Smoke is a very dense and very much visible 'cloud' of smoke. Low smoke is a sort of smoke effect which stays low to the ground, and haze is a very 'fine' effect which isn't visible to the naked eye, but allows beams of light and similar things to be seen. We can't really recommend equipment unless you clarify which it is you want, as you mentioned all three in the same sentence! Also, what sort of budget do you have?

 

I'll leave 2, 3 and 5 to someone who has more of a clue than me!

 

Regards,

Mark

[TheRave]

1. Returns = To the mixer, Sends = From the mixer. The only real difference between them is the gender of the connectors. A 24/8 multicore has 24 channels for inputs (mics, etc.) to plug into and 8 channels for outputs to plug into (monitors/amps etc.). The sends are used to output signal from the desk back to the stage. In theatrical spaces they will be less useful as speakers are normally have dedicated send. You can always make sends into returns and visa-versa using gender-benders but just make sure you don't get confused.

 

2. The length or run really depends on if they are balanced/unbalanced and what kind of signal it is (what kind of mic/input). Always try and used balanced cables and signals as they will reduce most interference.

 

3. I'm not an amp expert but I would say splitting signal between the amp and the speaker is dangerous. I would advise getting another amp and if necessary split the signal before the two amps.

 

4. Hazers are different from smoke machines. Hazers produce a small amount of thin smoke and are mostly used to highlighting lighting effects. Smoke machines can produce a large volume of smoke. I'm no expert on machines but I'm sure someone can advise you.

[LampTramp]

Try a Radial engineering JPC Sterio PC DI Box that does the trick.

Have a look on the le Maitre web site for low smoke or foggers.

[Bobbsy]

1. Returns = To the mixer, Sends = From the mixer.

 

Sorry, but to avoid confusing the poor OP, you have this backwards. From the the point of view of a stagebox, the "sends" are the circuits from the stage to the mixer and the "returns" are feeds from the mixer back to the stage. That's why the boxes the OP has seen have more sends than returns. At the risk of confusing the OP myself, I'll mention that you often use the Aux Sends on the mixer to feed the returns on the multicore...that may be what you were thinking of.

 

3. I'm not an amp expert but I would say splitting signal between the amp and the speaker is dangerous. I would advise getting another amp and if necessary split the signal before the two amps.

 

It is often possible to run more than one speaker off a single amp output but you're right...simply connecting a Y splitter is not the way to go about this. There are several considerations, especially the impedance of the speakers (which effectively reduces each time you add another speaker in parallel) and the ability of the amp to work at the resulting impedance. It's also worth considering that more speakers are certainly not always better since the coverage will overlap which may cause a muddy, harder to understand sound. There have been quite a few threads about both impedance matching and the desirablity/placement of multiple speakers. I'd suggest to the OP that he does a Blue Room search on terms like "speaker impedance" and "centre cluster" etc., have a good read with a pint or two in hand, then come back with more specific questions.

 

Bob

[Just Some Bloke]

3. We have in our Theatre, 2 Speakers, I would like to up this to 4 speakers (sound output all around room pointing at majority of audience).

 

now I have a 600w Amp, and its 300 per channel, so how can I hook this up to 4 speakers if there are only 2 outputs out the back of it? there a way of splitting cable so 1 output goes to 2 speakers? to I will have 2 left 2 right?

 

Many speakers have 2 sockets on the back. This is so you can connect another speaker by linking from the first. This is by far the best way of doing what you are asking.

 

HOWEVER, as Bobbsy says, you will need to do your sums to check the impedence of the speakers and the minimum impedence that the amp will run. For example, if the amp quotes 300w per channel into 4 ohms and your speakers are 8 ohms each you'll be OK. If the amp says it will run on a minimum impedence of 2 ohms and your speakers are 4 ohms each, you'll be OK. However, if your amp quotes a minimum impedence of 4 ohms and your speakers are 4 ohms each then you can't add any more.

 

The sum, difficult to write on this forum as a sum, is 1 over total impedence = 1 over impedence A + 1 over impedence B + 1 over impedence C (if you add a third speaker). Thus, 3 x 8 Ohm speakers in series gives you 2 2/3 Ohms etc.

 

Hope that helps.

[Shez]

Thus, 3 x 8 Ohm speakers in series gives you 2 2/3 Ohms etc.

 

To clarify a little, whilst the speakers will be connected in a daisy chain manor, they are actually connected in parallel rather than series.

[Rob_Beech]

By far the more important fact of the 2 as Bob mentions is the coverage issue. You may create more un-necessary problems by adding more speakers. Particularly if these are run from the same amp channels, and yet are in different parts of the room. You can create horrible sounding systems by adding more boxes without setting things up properly. Often, with boxes that are not designed to array in any specific manner are just piled up together and wired in however they want you cannot even begin to get a pleasant sound from the system. Indeed, you may get a better and often equally loud sound by throwing half of the boxes back in the van. 1 box per area wherever possible. If you need the SPL for 2 boxes to cover the same area (on the same side) then you need to look at the boxes you are using and how well they array.

 

Keep it simple, it usually works much better.

[ashrobinson]

Thanks all for the awesome replies, have only just realised ive posted in the sound forum (some of it was related to sound though) apologies for that.

 

Will take all of your advice onboard, thanks for explaining Stage box, makes sense now.

 

as for the spakers I will plan carefully and see What I want to do,

 

regarding the Low smoke, I think thats what I am looking for, to enhance the atmosphere in our theatre Any reccomendations on those?

 

I have a budget of around £6000, but this is to cover sound, lighting and general maintenance of the theatre AV, so I need a fair bit for projector servicing and any other problems that may occur.

[TheRave]

For low lying smoke there's a number of options:-

 

Dry ice machine - Expensive and hassle dealing with dry ice.

 

Smoke machine and electric chiller

(could be one unit or separate units) - Chillers are expensive but only one off cost. If separate chiller the smoke machine can be used to make normal smoke.

 

Smoke machine and ice/water chiller

(could be one unit or separate units) - Not as expensive as the electric chiller and still works well. Running costs of ice/water are not bad but machine requires refilling to keep the smoke low-level.

 

Smoke machine and home made chiller - Just the cost of the smoke machine plus some other cheap items. Works ok, not as well as the ones above but overall much cheaper.

(http://gotfog.com/fog_machine_chiller2.html)

I've just made one of these and it works fine for what we need it for.

[Just Some Bloke]

Thus, 3 x 8 Ohm speakers in series gives you 2 2/3 Ohms etc.

 

To clarify a little, whilst the speakers will be connected in a daisy chain manor, they are actually connected in parallel rather than series.

Apologies for that slip of the tongue. :)

[ashrobinson]

have yet another query,

 

Have been given £1000 for a PA system, to be used mainly for sports days and other events, now I would like to incorporate into my existing system in our theatre, with another amplifier this is possible, whats best to use? Speakers wouldn't be used in wet conditions (hopefully) but can I purchase some outdoor casing for them?

 

Heard good things about Mackie speakers, so reaslly what im asking,

 

what PA speakers + Amp should I get for what I have? I can sort out a mixer etc just stuck on those with some stands!

 

Cheers,

 

Ash

[Shez]

Have been given £1000 for a PA system, to be used mainly for sports days and other events, now I would like to incorporate into my existing system in our theatre

 

I think you'll be looking at very different equipment for theatre and for outdoor sports day type applications. If it were me, I'd probably be looking at 100v line / megaphone type solutions for sports day.

[Sirch Sound]

have yet another query,

 

Have been given £1000 for a PA system, to be used mainly for sports days and other events, now I would like to incorporate into my existing system in our theatre, with another amplifier this is possible, whats best to use? Speakers wouldn't be used in wet conditions (hopefully) but can I purchase some outdoor casing for them?

 

Heard good things about Mackie speakers, so reaslly what im asking,

 

what PA speakers + Amp should I get for what I have? I can sort out a mixer etc just stuck on those with some stands!

 

Cheers,

 

Ash

 

The problem with what your trying to achive here is mainly the british weather. Not only will all this equipment become very dangerous if it suddenly deicdes to pour, but it will also ruin all of your gear. So, as shez said, the best way to do this would be to look at a 100v line system. This is slightly different to the system you currently have in that it uses horns, which are more weatherproof than the speakers you currently have, along with many other diffrernces, however you wont be able to prower this off your existing amp as you will need a special amp, which im sure someone with more experience of these systems will go into if your interested in it.

 

As for mackie speakers, its like saying I have herd ford make cars. You carnt simply say a make is good or bad, as there are so many circumstances in which a speaker will vary. For example you have something like a behringer cab, very good cabs for the money and the choice of many Dj's and young bands, which is fine in there situation. However you then have something like a meyer audio line array system, which needs to be flown, this involves hanging it from wires from the room for use with much larger audiences. However these systems are not exchangeable, you couldnt use the behringer cabs for a venue contaning many thousands of people, but you also couldnt use the meyer audio system for the small bands and Dj's, mainly because they dont have the facilitys to fly the system.

 

As you can see there are so many different senarios when a different brands of speaker perfom much better, regardless of the cost.

 

Sorry I might have gone a little o/t there!!

Rich