To me, if I need 50 watts to cover a venue, I will setup 1.5 kilowatts. That's if I control the mix. If I don't, then it's 50 watts. (I've replaced too many tweeter diaphragms.)
I've been called in to fix small club systems on occasion. Every time, I ask the bartender for two bar towels. I stuff one into each metal midrange horn. Typically, that's worth a shot or two of top shelf from a grateful owner, and their consternation at the installer. And, I lived in a small town, so word spreads when you fix nagging problems with a dish towel and no charge.
If they have a good eq, I'll smiley face the curve about 10 dB.
I of course, do not do this for a living so had that luxury .
Jn
I've been called in to fix small club systems on occasion. Every time, I ask the bartender for two bar towels. I stuff one into each metal midrange horn. Typically, that's worth a shot or two of top shelf from a grateful owner, and their consternation at the installer. And, I lived in a small town, so word spreads when you fix nagging problems with a dish towel and no charge.
If they have a good eq, I'll smiley face the curve about 10 dB.
I of course, do not do this for a living so had that luxury .
Jn
@jneutron: I do not know what "metal midrange horn" you are referring to and why they need stuffing.
about the 1.5 vs 0.05kW: Excessive clipping of an underpowered amp can kill the tweeters - and ONLY the tweeters. The woofers are never affected in that case. (Of course, crazy headroom overkill amping can kill both woofers and tweeters, if the headroom is abused).
about the 1.5 vs 0.05kW: Excessive clipping of an underpowered amp can kill the tweeters - and ONLY the tweeters. The woofers are never affected in that case. (Of course, crazy headroom overkill amping can kill both woofers and tweeters, if the headroom is abused).
Back in the day, most of the pa cabs had a woof and a metal horn. Some added a few piezo as well. They were loud and obnoxious, so much so that stuffing the throat was the only solution.
And yes, I agree with you on the clip thing. In my experience, an idiot will kill the tweets no matter what the power you give them. I suspect clipping energy of a 50 watt amp won't wipe my 2 inch dia tweet coils. And, I already fixed the coils anyway. By design, the Manu neglected to bond the tweeter coil wire after it leaves the coil pack, so the floating conductor was still in the gap field and clipping ultrasonics would high cycle fatigue the loose wire till it fractured. I bonded them down out of the replacement box.
When I run it, I prefer major headroom. It is always easy to turn it down. Last gig required about 25 to 50 watts for outdoor crowd public address, I wanted the 1.5kw in the event of an emergency.
Jn
Putting a resistor between the amp and high pass network works better than stuffing a towel in the horn, and makes it last longer when clipping, too.
For systems designed to be run in clip continuously, use a bigger HF driver than necessary, and pad it (with a 100 watt resistor, or combination that takes that much). Cheap 2” exit/3” coil drivers work well. They don’t have as nice a top end but when clipping who cares. And use no larger an amplifier than the woofer’s RMS rating. Then the problem becomes amplifier shut down, but that’s clearly on the user.
For systems designed to be run in clip continuously, use a bigger HF driver than necessary, and pad it (with a 100 watt resistor, or combination that takes that much). Cheap 2” exit/3” coil drivers work well. They don’t have as nice a top end but when clipping who cares. And use no larger an amplifier than the woofer’s RMS rating. Then the problem becomes amplifier shut down, but that’s clearly on the user.
I'm afraid that's a myth that's been perpetuated.
The increase in the level of harmonics from a clipping amp is pretty much negligible - less than a couple of percent. It's simply the increase in long-term average power that kills the drivers, woofers included.
Chris
The reason that myth has been perpetuated is because the average power of unclipped signals is very very LOW. Even in tha safe zone you see some clipping. Do the “1/8 power, pink noise “ power test they do for amplifiers to get the typical AC current draw numbers. The waveform is clipped, and the clip lights come on. And stay on. That’s considered the typical design limit for both amps and speakers. It is expected that f you run it harder something will give.
What I see in error on the typical analysis is that only the clipping of the fundamental is considered.
In typical music, if I run past clipping, not only are the clipping products piling onto the pig pile, but the high frequency content coming through when the amp is not clipping is the problem. If you are close to tweet capacity just before clipping, and then go 50% more, the hf content will increase 50% more, but only during the portion of the waveform where clipping is not occurring.
Jn
In typical music, if I run past clipping, not only are the clipping products piling onto the pig pile, but the high frequency content coming through when the amp is not clipping is the problem. If you are close to tweet capacity just before clipping, and then go 50% more, the hf content will increase 50% more, but only during the portion of the waveform where clipping is not occurring.
Jn
If you look at what’s in a typical 500 watt rated speaker, you get a woofer that can take 250 watts AES, which translates to 125 watts of thermal load. And a tweeter good for 10 watts. If used with the proper amplifier, and not driven to where distortion is objectionable, the tweeter will hold. Unfortunately, it is probably not very loud so the tendency is to push up the volume. Push 20 watts of average power into the tweeter by clipping or excessive compression, and it dies. A tweeter that can actually take it would cost more than the woofer and more than double the retail price of the speaker.
Interesting article from Rod Elliott about clipping and destroying tweeters:
Why Do Tweeters Blow When Amplifiers Distort?
The way I think about it is:
Clipping adds harmonics that weren't there before
Clipping also removes HF content while it is happening. The amplifier will normally clip on low frequencies first, and once the amplifier output is at the power supply rail, it cannot produce any HF content
These two tend to cancel out meaning that it's mainly the increase in power that kills the tweeter
Brian
Why Do Tweeters Blow When Amplifiers Distort?
The way I think about it is:
Clipping adds harmonics that weren't there before
Clipping also removes HF content while it is happening. The amplifier will normally clip on low frequencies first, and once the amplifier output is at the power supply rail, it cannot produce any HF content
These two tend to cancel out meaning that it's mainly the increase in power that kills the tweeter
Brian
AMEN!!!
But I still think there is a need for good limiters on individual vocal mic channels, as well as equalizers that can tailor the singer's sound better than the typical 'bass + treble' controls found on many club mixers.
And I also believe that bi-amping the speakers will help immensely to alleviate clipping.
Last edited:
sure why not make the signal chain more complex and turn "idiot" operators loose on that...oh wait most "poor bar systems" don't have channel inserts so patching in a good quality comp/limiter is a moot point...
and how is bi-amping the speakers going to resolve a problem that starts at the mixer input stage?
and how is bi-amping the speakers going to resolve a problem that starts at the mixer input stage?
I guess the bottom line is all about the bottom line - you get what you pay for. Cheap speakers have their limitations. And if you need processing equipment in order to do a professional sounding mix before you even get to the speakers, you need to pay for that too. While a real mix-meister may be able to make the most out of what is there, there are limits. And idiot users can always be trusted to do their worst.
I put together a nice triamp nightclub system, had all the knobs available in a rack to the left of the dj so I could tailor the sound to the recording, the mikes, everything. I loved the flexibility it offered me.
After two weeks of re-adjusting every single freakin knob back to reasonable every night, I put a 1/4 inch thick sheet of acrylic over everything. Leaving me only right table, left table, and master gain to play with. But at least, the entire system setup stopped changing.
Some people do not have the ability to understand the complexity, so cannot be trusted at the controls.
Jn
After two weeks of re-adjusting every single freakin knob back to reasonable every night, I put a 1/4 inch thick sheet of acrylic over everything. Leaving me only right table, left table, and master gain to play with. But at least, the entire system setup stopped changing.
Some people do not have the ability to understand the complexity, so cannot be trusted at the controls.
Jn
i'd still like to hear dotneck's reasoning on this one. specifically with respect to vocal mic use.
Rod Elliott explains it better than I: BiAmp (Bi-Amplification - Not Quite Magic, But Close) - Part 1
It IS true, as you point out, that the signal need to be limited in the INPUT first and foremost. Now the bi-amping will not help as much on a vocal-only system, it's true. But it's still a very good idea for any "PA" system.
It IS true, as you point out, that the signal need to be limited in the INPUT first and foremost. Now the bi-amping will not help as much on a vocal-only system, it's true. But it's still a very good idea for any "PA" system.
That can work if the band plays as a "band" and for the greater good of the audience.
Of course you still need a decent PA and a room that is not an echo chamber.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.