Speaker fuses

[paulears]

This is normal. If you want bomb proof sound for schools and colleges they must be simple and over, not under specified. Powerful amps and speakers capable of running all day at high power so volume is never an issue. With the amps in a rack it’s easy to back them off so no matter what they plug into the inputs it won’t get stressed. A drive rack is a bit pointless because you really don’t have a system that needs one. If it does it’s job they will complain it’s quiet because you have to adjust it to protect too feeble a speaker. You’ve got the equivalent of a big engine in a tiny car with 50mph limited tyres and are swapping the manual gearbox for an auto. Unless you drive slowly, what’s the point? You still need better tyres.

[paulears]

This is normal. If you want bomb proof sound for schools and colleges they must be simple and over, not under specified. Powerful amps and speakers capable of running all day at high power so volume is never an issue. With the amps in a rack it’s easy to back them off so no matter what they plug into the inputs it won’t get stressed. A drive rack is a bit pointless because you really don’t have a system that needs one. If it does it’s job they will complain it’s quiet because you have to adjust it to protect too feeble a speaker. You’ve got the equivalent of a big engine in a tiny car with 50mph limited tyres and are swapping the manual gearbox for an auto. Unless you drive slowly, what’s the point? You still need better tyres.

[Junior8]

This is why back in the day equipment was manufactured especially for schools by outfits like Clarke & Smith. It was of mediocre technology even for the time and the performance was often worse but it was by and large indestructible could be dropped from great heights with a good chance of survival and could be repaired, in the are event this was necessary, by the electrical shop on the corner with bits off the shelf or readily available form the RS catalogue. High end equipment of high power and the everyday rough and tumble of school life is a mix that will always involve the risks outlined without proper training, management and most importantly accountability.

[sunray]

1575444989[/url]' post='578960']

Thanks for the help everyone. I don't actually have a budget get to update the speakers. Powered speakers would work for me as they are so high up in a sports hall and it has cabling for passive layed beneath the floor and up the wall. I am going to look into the drive rack a bit more as it does come with quite cool features that is not there currently e.g fbq and eq. But reading what you all say has helped in actually identify the problem. It was originally fine and then someone whacked the amps up therefore the speakers made terrible noise. They left them for a while at it and obviously the HF broke eventually. When it broke they just wacked the amps up even further. (This is the teachers I am talking about)

For school systems I try to make them foolproof with hidden attenuation (often constructed with resistors and heat shrink within a cable) etc

[timsabre]

For school systems I try to make them foolproof with hidden attenuation (often constructed with resistors and heat shrink within a cable) etc

Do you really find that works though? They normally just redline some other part of the system to get the volume they want and now everything is a square wave.Paul is right, it needs to be a loud enough system that it can run comfortably at whatever input they throw at it. Reasonable quality (i.e. not disco) powered speakers which have inbuilt protection have worked out best for me.

 

[Jupton24]

Thanks for that. Like what Paul says I will need to find a bigger budget to get better speakers. I won't ask for speaker recommendations as I think it may get a bit over crowded with different types. But in general is EV a good make for what they cost?

[timsabre]

EV is a good make yes, possibly on the pricey side as a "brand", but there are about a million options. Alto Truesonic powered range are well regarded as a cheap option.

 

In the meantime the main thing you need to avoid is people driving a distorted signal into the speakers because that's what kills the horns / HF drivers. This happens when they can't get enough volume so they crank the volume on the source / input mixer / whatever you've got on there and it clips. So you need to get a good gain structure set up so that when someone plugs in their phone or tablet they get a good volume out without having to turn everything up to max. If it's a sports hall you might not be able to do this as the speakers won't be loud enough to fill the room...

 

[paulears]

For school stuff, it's always worth perusing the Thomann site in Germany. Loads of schools buy from them, especially their own brand stuff, which although Chinese sourced, has the full warranty for 3 years on most items. Their range of passive and active speakers is pretty good, and offers good value for money and has decent performance. They also do loads of sort of disposable kit - cheap mics that the kids can wreck and loads of useful kit, including guitars and drums!

[J Pearce]

When I looked after a number of dance studio installations in a school, my design scope was always blow ears before drivers. It then became an H&S issue to regulate volume, which was rather handily 'someone else's problem'.

[Jupton24]

J Pearce that's a good idea except that young kids will be listening to the audio so you do 10% of what you feel is fine for your ears. If I put 2 10inch ones on the smaller amp and 2 15 on the bigger one will I occur any problems?

[J Pearce]

Our RAs firmly laid the responsibility of looking after hearing with the teacher in charge. Had the responsibility been with me I would have pushed for a formula sound limiter setup.

[sunray]

1575456542[/url]' post='578972']

1575452461[/url]' post='578968']

For school systems I try to make them foolproof with hidden attenuation (often constructed with resistors and heat shrink within a cable) etc

Do you really find that works though? They normally just redline some other part of the system to get the volume they want and now everything is a square wave.Paul is right, it needs to be a loud enough system that it can run comfortably at whatever input they throw at it. Reasonable quality (i.e. not disco) powered speakers which have inbuilt protection have worked out best for me.

 

The biggest problem I find with schools is somebody manages to sell them a system that is far too complex and then typically the gains get cranked to full so the vol controlled by cracking the fader open. As an example I found a 48 channel desk and 24 channels of radiomics driving 2 Crown 1200's along with a rack full of players of various flavours.

I try to spec amps which are adequate for the job but not over the top and basic speakers rated about 50% or more higher. For a junior school in a hall 14x8m I supplied a 150wpc into 4ohm and 160w 8ohm basic speakers (no horns) in 2012 and set attenuation for 1KHz to 83dB. I assist setting up for their end of year show every year and so far amp and speakers are as fitted.

Edited December 4, 2019 by sunray

[KevinE]

The Formula Sound AVC2 is designed to prevent people blowing-up speakers. It works. It is used by sound system contract rental companies to protect their installed assets when speakers and amps are used by people who are likely to blow them, either by accident or on purpose. It must be set-up before use.

 

Take a look or chat to them.

 

Formula Sound AVC2