Hi,
I am struggling to get my head round working out how much watts I am sending to my speakers as unfortunately last week my daughters band managed to damage there speakers during a live gig.
The currently only use the PA for vocals and the rest of the band use there own guitar amps.
the setup they have is:
Shure SM58 Plugged into a Mackie CFX12 (Mixer) in turn connected to A Samson s2000 AMP which in turn was connected to 2 x Studiomaster GX15 passive speakers (Until the started smoking and are now broken or at least the crossover board and tweeters are, the bass cone seems ok in both).
We usually set the mixer to Unity on the mic channel and also Unity on the master output.
We set the gain so that it only flashes when the vocalist is doing her loud parts.
Once this is set we usually turn the AMP up till we get the vocals coming out the speakers and being able to be heard above the rest of the band.
And this is where we feel we go wrong and end up blowing speakers. The amp has 2 dials on the front where fully counter clockwise it reads -80db and fully clockwise 0db we usually end up setting it around between -10db and 0db. The speakers are rated at 250W (continuous), 1000W (peak).
I feel we are doing wrong but just not sure how.
Again please bear with me as I am an amateur in this game.
Many thanks for your time.
I am struggling to get my head round working out how much watts I am sending to my speakers as unfortunately last week my daughters band managed to damage there speakers during a live gig.
The currently only use the PA for vocals and the rest of the band use there own guitar amps.
the setup they have is:
Shure SM58 Plugged into a Mackie CFX12 (Mixer) in turn connected to A Samson s2000 AMP which in turn was connected to 2 x Studiomaster GX15 passive speakers (Until the started smoking and are now broken or at least the crossover board and tweeters are, the bass cone seems ok in both).
We usually set the mixer to Unity on the mic channel and also Unity on the master output.
We set the gain so that it only flashes when the vocalist is doing her loud parts.
Once this is set we usually turn the AMP up till we get the vocals coming out the speakers and being able to be heard above the rest of the band.
And this is where we feel we go wrong and end up blowing speakers. The amp has 2 dials on the front where fully counter clockwise it reads -80db and fully clockwise 0db we usually end up setting it around between -10db and 0db. The speakers are rated at 250W (continuous), 1000W (peak).
I feel we are doing wrong but just not sure how.
Again please bear with me as I am an amateur in this game.
Many thanks for your time.
Its no Distressor by any means, but IIRC better than most in its price range: FMR Audio RNC1773 Really Nice Compressor RNC B&H Photo Video
Something else to perhaps keep in mind is that letting a power amp clip will create more high frequencies. That can overheat and damage an HF driver. Therefore, better to make sure the power amp won't clip. Sometimes its better use a power amp with a higher power rating than the speakers, as that should help avoid clipping.
One last thing to consider, a good band will learn how to control the volume level of each of its instruments to get a good mix balance where the audience is. Drummers often pound on the drums way too hard. Guitarists use amps that easily overpower most PA systems, etc. Therefore if they can't afford a more powerful PA then they should adjust down the level of the other instruments accordingly. Playing louder can come later if they are good enough to make the money to pay for the PA required.
Something else to perhaps keep in mind is that letting a power amp clip will create more high frequencies. That can overheat and damage an HF driver. Therefore, better to make sure the power amp won't clip. Sometimes its better use a power amp with a higher power rating than the speakers, as that should help avoid clipping.
One last thing to consider, a good band will learn how to control the volume level of each of its instruments to get a good mix balance where the audience is. Drummers often pound on the drums way too hard. Guitarists use amps that easily overpower most PA systems, etc. Therefore if they can't afford a more powerful PA then they should adjust down the level of the other instruments accordingly. Playing louder can come later if they are good enough to make the money to pay for the PA required.
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Those speakers are around £100 each in the UK, so you might not have done anything wrong, but I think you will need to spend a bit more to get reliability for continuous use. 15" speakers aren't ideal for vocals so I would recommend a decent 10" or 12" as you will get better dispersion in the vocal range. If you are replacing them, look at active speakers as they usually have protection built in to stop them being damaged from playing too loud etc.
Brian
Brian
Your 1000 watt per channel amp can easily overpower those tweeters. Rein it in some.
I assume you use the graphic EQ on the mixer? DO you have the typical "smiley face" curve going? That last slider on the right, is it the highest setting of the row? Play some music through the system and drop that slider to zero. DO you really hear much difference? That is sending a lot of high freq signal to your tweeters, stressing them. Point being, don't turn the treble way up.
I assume you use the graphic EQ on the mixer? DO you have the typical "smiley face" curve going? That last slider on the right, is it the highest setting of the row? Play some music through the system and drop that slider to zero. DO you really hear much difference? That is sending a lot of high freq signal to your tweeters, stressing them. Point being, don't turn the treble way up.
Some basics, audio power requirements peak at low frequencies. For your use with an SM58 the energy peak will drop off about 3 dB per octave above 100 hertz.
A 15" woofer might be good to 600 hertz. So based on your amplifier's real power output, if we have 350 watts of power at 100 hertz full output, we would expect 175 watts at 200 hertz, 88 watts at 400 hertz and about 60 watts or more at the crossover frequency for a total tweeter power above 110 watts. (Actually a bit more due to the mid high peaks in the microphone) I don't know of any piezo driver that can actually handle such power.
You probably could replace the driver with a traditional voice coil design unit to handle the power. I would however pick up automotive dome light bulbs and wire one in series with each of the high frequency crossover inputs.
https://www.amazon.com/HELLA-DE3175...locphy=9005927&hvtargid=pla-589436356940&th=1
A 15" woofer might be good to 600 hertz. So based on your amplifier's real power output, if we have 350 watts of power at 100 hertz full output, we would expect 175 watts at 200 hertz, 88 watts at 400 hertz and about 60 watts or more at the crossover frequency for a total tweeter power above 110 watts. (Actually a bit more due to the mid high peaks in the microphone) I don't know of any piezo driver that can actually handle such power.
You probably could replace the driver with a traditional voice coil design unit to handle the power. I would however pick up automotive dome light bulbs and wire one in series with each of the high frequency crossover inputs.
https://www.amazon.com/HELLA-DE3175...locphy=9005927&hvtargid=pla-589436356940&th=1
More likely a typo. The same loudspeaker with their built in amplifier is listed as 28 dB louder.
I suspect that is a 1 watt 1 meter rating for the passive unit. But then it seems high, probably on axis measurement falsely high by the woofer beaming at the test frequency.
I also see they are using 3,000 hertz as a crossover frequency in the active one. To avoid beaming that would require a cone size of 2.25" !!!!
I suspect that is a 1 watt 1 meter rating for the passive unit. But then it seems high, probably on axis measurement falsely high by the woofer beaming at the test frequency.
I also see they are using 3,000 hertz as a crossover frequency in the active one. To avoid beaming that would require a cone size of 2.25" !!!!
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This is a case of not enough Rig for the Gig... or at least not enough speaker. Your amp is more than powerful enough to melt these things with any kind of continuous signal, and no.. a compressor won't help it would actually blow the speakers quicker. I think you are just failing to understand how much power is needed top get vocals over top of a couple guitars and a drum kit, IMO 250w speakers just aren't enough even if they aren't low budget, you need at least double that power handling in a better quality product.
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If the speakers are frying then either amp is too big for them or your clipping the output which again is driving them too hard.
I ran a mobile disco for many years with 4 off Fane 12-50WRMS and a 225WRMS amplifier. It got hammered every night but never blew the speakers.
I do remember a syndrome called "band war" where someone turns up their guitar so everyone else does the same as they can no longer hear their instrument. Before you know it everyone is maxed out and blowing up equipment.
I ran a mobile disco for many years with 4 off Fane 12-50WRMS and a 225WRMS amplifier. It got hammered every night but never blew the speakers.
I do remember a syndrome called "band war" where someone turns up their guitar so everyone else does the same as they can no longer hear their instrument. Before you know it everyone is maxed out and blowing up equipment.
Markw4.. you need to read up on power handling and power compression in loudspeakers.. AES E-Library >> Heat Dissipation and Power Compression in Loudspeakers
Loudspeaker power handling
Signal limiting can be an effective tool for speaker protection but the trick is doing it without compressing the signal, in general that is only possible with a digital limiter. An analog compressor/limiter will raise the average signal level which puts more continuous power into the drivers.. not less, and that will actually accelerate driver failure.
Effective speaker protection involves several different things, peak and thermal power limiting and over excursion protection. Getting all that in a rack component is very expensive... it would cost more than the OPs whole PA system in this case. This is where modern powered speakers offer a much better bang for the buck as they often include all of this protection for a very reasonable price.
Loudspeaker power handling
Signal limiting can be an effective tool for speaker protection but the trick is doing it without compressing the signal, in general that is only possible with a digital limiter. An analog compressor/limiter will raise the average signal level which puts more continuous power into the drivers.. not less, and that will actually accelerate driver failure.
Effective speaker protection involves several different things, peak and thermal power limiting and over excursion protection. Getting all that in a rack component is very expensive... it would cost more than the OPs whole PA system in this case. This is where modern powered speakers offer a much better bang for the buck as they often include all of this protection for a very reasonable price.
Understood that improper use of compression could increase average power dissipation. The compressor I suggested can operate at high enough compression ratios to act as a peak limiter (although not as a lookahead limiter). Sometimes a compressor stage is used before a limiter so that hard limiting is approached more gradually, which I believe is done for SQ purposes.
You should set the mic gain lower so that the clip light doesn't engage. Clipping in the signal chain will cause more power to be dissipated in the the tweeter.
The speakers are pretty rubbish. For simple setup as others have recommended get a high quality active speaker as it will have built in limiting. For vocals 10-12" is best, higher end RCF, QSC, Yamaha etc. You might also want to consider that your whole band may be too loud depending on the size of the venues that you're playing.
The speakers are pretty rubbish. For simple setup as others have recommended get a high quality active speaker as it will have built in limiting. For vocals 10-12" is best, higher end RCF, QSC, Yamaha etc. You might also want to consider that your whole band may be too loud depending on the size of the venues that you're playing.
i guess i have a different philosophy on compression and limiting, if i can keep the average well below what the system can handle peak i'm happy , the human voice has a wide dynamic range and a screaming metal head or rap artist cupping the mic has the ability to overload the judiciously, set at soundcheck, gain of vocal channel !!!
there's been no mention of feedback or other issues such as overall clarity or ability to get the vocal over the stage din so i may be remiss but i still think a malfunctioning amp is at play...
there's been no mention of feedback or other issues such as overall clarity or ability to get the vocal over the stage din so i may be remiss but i still think a malfunctioning amp is at play...
A LOT and sadly WAY MORE than they can handle.
Woofers in general handle the rated cabinet power, Tweeters/HF drivers about 10% of that.
We are talking actual power delivered to speaker terminals, not "complete system power".
Not bad as a starting setup but that does NOT guarantee not surpassing maximum levels/Power at all.
Those are gain controls, not maximum power controls by any means.
For that you need limiters which are "automatic" volume controls which are all the time measuring signal , independent from operator who will always be "too slow" or "too engaged in the Show" to be "safe".
Even a 5 second feedback squeal will pass through before he kicks gain fader down ...long enough to fry a hair thin wire voice coil which by specs is about coin/small cookie size.
Specs say 1.35" diameter so some 34 mm.
Again, hair thin Aluminum wire,you look at it sideways and it goes up in a puff of smoke.
Doubt it stands more than 20/25W RMS at the Tweeter terminals, so it is YOUR job that it does not get more than that.
Since the band plays LOUD, you must set up vocals VERY loud.
I told you
This means nothing.
Those are gain controls, not power controls.
Forget Peak/Musical/PMPO/Dynamic/funny Watts, only real ones here are RMS Watts, which are nowhere on the speaker datasheet, except indirectly.
Not even "Program" Watts are safe, although if honest give a clue.
Reading some brochures:
one states:
peak is for the birds, continuous may mean "Continuous Program" which is not defined anywhere but typically means "you can use X size Program Output Power: 170W RMS, with "normal" Music, and NOT CLIPPED" and is (again typically, it´s not an official standard) assumed to be 2X RMS power, so those cabinets are rated 125W RMS.
Which is sort of confirmed by the powered cabinet brochure.
Of course they are not fools, this is s cheapish cabinet but Studiomaster is a serious Company, they do not want their cabinets blowing all over the place, so they fit them with a SAFE power amp.
And what do they fit there?
Not kidding, read it yourself.
GX 15A – Studiomaster
which in good English means:
Safe with a 170/2=85W RMS amp under any condition.
or more useful:
Safe with a 170W RMS *limited* amp so it never ever clips.
Of course the built in amp must have a built in limiter, it´s standard Industry practice.
You want to play it safe using Studiomaster GX15 cabinets?
Buy the powered ones .... of course you will have only 170W RMS available per cabinet .... but that´s the Real World spec, what they can truly handle.
Can you replace the driver (hope you have not blown the crossover and if you did, add that to the repair bill) and reuse those cabinets?
Yes, of course, I would repair them anyway (unless more expensive than a full new cabinet) but then LIMIT THEM TO 170W RMS, period, which requires a good external limiter and some means of adjustment so power amp never puts out more than 170W RMS per channel into 8 ohms, some 36V RMS .... CLEAN.
Guess that will sound like under use of your equipment, and it is, but that´s the realistic safe limit.
The GOOD solution?
Get PRO speakers which can handle real 750W RMS or better.
Not kidding.
Yes, they will be EXPENSIVE.
now reading amp brochure.
That amp is a BEAST, 1000W RMS per channel Class AB into 4 ohm, so probably around 700W RMS into 8 ohm. A beast.
Even if limited so not to clip, it will SMOKE those cabinets.
They are THE bottleneck in your system, completely unsuitable, get much better ones.
Sorry
I hate filling landfills up so IF possible I´d repair them anyway but then only as side fills/monitors , rehearsal room only vocals, Keyboard cabinets, or Bass Guitar cabinets, wiring woofers straight to input jacks, no crossovers.
Plug horn cutout with a piece of plywood or simply let them unconnected.
Or sell them as is, "for parts" or "to be repaired".
Just curious, what is your Daughter´s band backline?
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FWIW, I've used my Faital 10HX230-based speakers (the midbass cone is rated for 250w) for running FOH for a live band. The band were on IEMs, no backline but acoustic drums, and the singers put earplugs in and then asked for another 10dB on the wedges.
It wasn't quiet, and I was leaning on those little speakers pretty hard.
The 10HX230s held up just fine, though. I was feeding them from a Powersoft T604, and I did engage the limiters.
A further FWIW, a compressor only ever reduces loud sounds. It's when the operator turns things up further that extra power is delivered.
Chris
Chris your coax's have a much better compression driver. I have taken apart speakers like the GX 15 and the compression driver is usually very basic. Things like a simple mylar dome with a voice coil barley larger than the throat and a simple bullet shaped phase plug, all with a weaker magnet than normal. The end result is a driver with lower sensitivity than normal around 100dB/2.83V combined with the poor power handling of a smaller than normal voice coil (1.35″ for the GX 15). Easy to burn out