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Yet another pa question


jezzaboy

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On 28/08/2023 at 21:30, jezzaboy said:

As the rest of the band don`t seem too keen on chipping in for the cost of the speakers, I have decided to buy them myself. Might save me some hassle further down the line if things go belly up.

 

More than likely I`m going to with the Alto 412`s. I reckon that they should do the job and cover any gig when we have to supply the pa.

Please don't take this as my telling you what to do but I feel sorry for anyone trying to choose PA speakers on the basis of specifications alone. The claims made by Alto are off the scale of credibility, it isn't just them either Yamaha are similarly over claiming and so are just about everyone else in an arms race where telling the truth will lose you sales.

 

this is what they claim

image.png.d2a612e032e5e83b77ee3573dff3ff7d.png

 

Now power handling is limited initially by the ability to dissipate power and for the bass unit also by excursion. Ultimately they are limited by the heat radiation of the voice coil  which in turn is limited by diameter. The 35mm diameter of the HF driver would indicate roughly 30W continuous power handling. So 450W  so they have an amp which will overdrive it 15x and burn it out in seconds if all the power ever reached the driver. The LF driver has a 63mm coil which will dissipate 3-400W. The sort of rating that Eminence/Fane/Celestion/RCF  for example show for their 63mm coil drivers. In practice almost none of these can handle those peaks over the whole frequency range because of excursion limits. Whatever these speakers claim they are actually 3-400W cabinets. The secret is of course that they are DSP speakers (Digital signal processing) where whatever the amp might do the digital processing stops damaging power levels ever reaching the speakers.

 

The probability is that the 12" drivers produce about 94db/W in the flat part of the lower frequency response. They may be louder in the distortion peaks under cone break up conditions. If they did handle 1600W that would still only get them to126db but the reality is that they will only produce an undistorted output of 120db, a long way from the 132db they claim. This is all just as well, you couldn't draw 5kw for a pair from a 13amp socket anyway and would seriously challenge a 30A ring main with anything else plugged in. 132db would very quickly send your audience off to the hospital with permanently damaged hearing. 

 

The reality is that the majority of 12" PA speakers are 3-400w units whatever they claim and that you can't trust any of the figures manufacturers give out. It does save them money in fitting the same amplifiers to a wide range of products and throttle them back to suit the drivers and it doesn't hurt to use a more powerful amp than the speaker can handle to get undistorted sound on some of the peaks but these claims are absurd and misleading.

 

Please don't try and choose a PA based upon over-optimistic specs. Lot's of people love their Alto's and they do represent good value for money but try and get to listen to them and compare them with other systems. The good news is that it is getting increasingly hard to buy an actually bad PA speaker and good ones like the better Yamaha's and RCF's are brilliant for the average band.  if you are going for the Alto's I'm guessing you are looking at new gear, that's fine but there is a reason why people are recommending other brands and that is direct experience. Going used brings these speakers well within your budget and easy to get your money out if you don't like them. Even if Yamaha are just as guilty as Alto in over-claiming.

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Use ten loaded mains and either fifteen or eighteen loaded subs. You can't do it right with full rangers. Mains need smaller woofers for midrange dispersion and they have to be pole mounted for projection. Subs need to be on the floor, clustered not split, preferably close to a wall for loading. For small gigs leave the subs at home. You can't do any of that with all in one box PA cabs. As for owning the PA, if you do you can get gigs providing sound that will pay for it.

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I guess my key learning point having had a similar £800 to £900 budget for a PA, is that if you want something that can deal with vocals really well then get one with a decent voice coil on the compression driver e.g. RCF 732A which has a 3.0" voice coil neodymium compression driver and "offers a unique vocal clarity and sound projection" (according to RCF, anyway, haha) but actually they're pretty decent.

 

I think you can hear the difference quite clearly in this little A/B

 

If you can find a pair of RCF 732As used they may just about be within your target budget. We ended up stretching the budget (shared between me and the singer) to get a pair of new 732As for the band - singer is now definitely sold on 732As justifying the extra we spent over the 912As I'd bought.

 

Edited by Al Krow
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4 hours ago, jezzaboy said:

@Phil Starr no problem mate, I know sod all about pa so any input is gratefully accepted.

 

I have been offered a set of Mackie SRM 450`s, made in Italy for a good price. From what I can gather, they are decent speakers?

I've never used them so probably not the person to ask, I've read the usual complaints about the recent ones not being as good as the Italian made ones but no direct experience. I think they used to use RCF drivers. I do know that back in the day a lot of bands managed to sound very good using them. Depends upon the price

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2 hours ago, Phil Starr said:

I've never used them so probably not the person to ask, I've read the usual complaints about the recent ones not being as good as the Italian made ones but no direct experience. I think they used to use RCF drivers. I do know that back in the day a lot of bands managed to sound very good using them. Depends upon the price

I’m not a big fan of Mackie speakers, especially compared to RCF. They just do not have the same balanced projection…just my opinion

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