I Grossly Underpowered my Speakers . . .
- Thread starter damacman
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55Redneck
Canadian Redneck
I'm just a simple redneck so the OP is waaay over my head. I just sit in my chair and turn my Pioneer SX D7000 up to a level that make my Luxman LX 104 MKII's sound awesome. I have no idea what the Luxmans are rated at but they seem to go well with the 120 watt 7000. I must say I care a lot more for the sound than the science of it all. 
PPstereo
Super Member
All I know is that "operator error" was in force when I first paired a Sansui 6060 (40watts/ch) with Infinity Quantum Jrs (4ohm) and somehow the volume control would get turned up in an attempt to recreate the levels of a Who concert (I was a teenager in the 70's; louder was better!)
Doubly dumb? Sure, I'll cop to that.
The result:
Here's the other dumb part - it happened on multiple occassions. The Jrs were rated for 25-200W, so I'm pretty convinced that it was clipping that fried those tweeters.
Haha yup did the same kinda stuff in my teens.
My car stereo I carefully picked every part for suffered a similar fate. But man for those 2 weeks it worked before the subs voice coil thermally detached from the former... you could hear the copper grinding if you pulled the cone up and down lol. And i set one of the fronts on fire. This appeared to be a case of over powering lol.
My inspiration was to be able to recreate Hendrix Woodstock star spangled banner at concert loud levels lol. But being able to recreate Who's young man blues live at the isle to concert like levels would also be an admirable goal
damacman
Resident Psycho
@restorer-john - so, do you disagree with the premise that overpowering is the actual cause of driver failure?
Also, the "250W" speakers to which I refer have (23) 1" Phillips tweeters each with a collective continuous power rating of 250W. So, I think I'm safe using them in the example as I have. Single tweeter and I'm with ya'!
Also, the "250W" speakers to which I refer have (23) 1" Phillips tweeters each with a collective continuous power rating of 250W. So, I think I'm safe using them in the example as I have. Single tweeter and I'm with ya'!
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stereofanboy
Addicted Member
That's just crazy talk. Everyone knows you blame the gun.
damacman
Resident Psycho
Know it well. Listen to that Benassi track and you'll know why I reference it. I don't know of anything with more upper octave energy.
Cogito
Well-Known Member
I don't deny that. However, that wasn't the point. The point was to demonstrate how NOT having enough power can indeed destroy tweeters. Driving the Pioneer into clipping was certainly the cause of the destruction. Contrast that to the ADCOM, which allowed me to apply considerably more CLEAN (un-clipped) power to the Polks without harming the tweeters.
twiiii
Lunatic Member
You are living in the present not in the past where the saying came from. Back in the day when speakers were rated around 30 to 60 watts, the tweeter in a 3 way system might be only rated at 5 watts rms. A lot of manufacturers, like Klipsch, University, EV, etc were building speakers with 6 db/oct crossovers. So when a little amp clipped the small tweeters couldn't take the power. Now the woofer might be able to handle 75 watts all day but when a Scott 299D rated at 40 watts actually putting out less than 20 a rated specs started clipping little 5 watt tweeters didn't have a chance. By the late 60's speakers like Klipsch were going to 12/db/oct crossovers and by the 70's 18 db /oct crossovers with active elements to protect their tweeters. Then came newer designs with new materials and by the 80's the issue was pretty much for gotten.
Altec and JBL two way systems HF diaphragms though rated at. 40 watts were actually closer to 14 watts RMS while the woofers were 10 times the capability. With 500 HZ crossovers it was the tweeter surround that failed. Altec developed modulation covers to limit the physical modulations. Then developed the much stronger plastic surrounds. JBL developed different surround patterns giving more strength.
Any way the worst period was the early disco days where the music featured electronic instruments with a lot of HF content forcing companies like Mac and Infinity to go to line arrays for better power handling above 4 KHZ. Something Bozak had been doing for years. Bozak developed new tweeters to extend their response. Some started using the horrible indestructible piezo tweeters to keep a lid on things. People found that AR speakers could take 3 times the power in the bass but when applied to higher frequencies destroyed tweeters, too. So new designs were created and new HF drivers used. Fluids were used in the gaps to try to dissipate the heat but the tweeters lost their soul that way.
I would guess by the 80's or 90s speakers were better capable of handling power across the spectrum. Thats when the fake power ratings again began. If a woofer could take 80 watts RMS, and a mid 80 watts and a tweeter 60 watts, we will just add them all together for a 200 + watts. Or most music only have 6 db peaks anymore so if speakers can handle 75 watts will say they are rated to 300 watts. Some woofers are rated at or above free air resonance. So that means the bottom octave is not included and where low bass can cause a woofer to exceed its excursion limits.
Thats how you get speakers rated at 1000 watts but when you powers them with 400 to 500 watts with music concentrated in a limited area's the drivers fail today. You always want to know the RMS power handling of each driver and the insertion loss for each driver of a crossover to make an intelligent answer as to the size of the amplifier you choose. Plus you need to know what type of protection the amp employs for itself and if any for the speaker.
You just can't be happy with a speaker with. a 86 db sensitivity and a lot of power when something fails when you are having a party or listening to powerful music seriously. So the best advice I can give is buyer beware, by more efficient speakers, and listen in moderation. What do I mean by more efficient. 94 to 96 db 1 watt 1 meter. Then choose an amp with adequate power for the peaks you want to produce with in the speakers capability. Yes that means bigger speakers or sometimes multiple subs. Give me a pair of Klipsch Cornwalls or Forte's and nice little Mcintosh 7100, 754, 122, etc and I would be happy. Or some of the JBL DD series. An older pair of XRT 22 or 290's would be great but now you need the 500 watt amps with Power Guard to keep a lid on every thing.
My speakers are 95 db efficient and rated at 100 watts RMS, I use 200 with Power Guard. Never a failure in many. many year. But then my average listening is only 4 watts with 20 watt peaks occasionally in stereo mode. About the same with higher peaks for HT model but with 7 channels. The rears and sides at about 10 watt peaks.
Altec and JBL two way systems HF diaphragms though rated at. 40 watts were actually closer to 14 watts RMS while the woofers were 10 times the capability. With 500 HZ crossovers it was the tweeter surround that failed. Altec developed modulation covers to limit the physical modulations. Then developed the much stronger plastic surrounds. JBL developed different surround patterns giving more strength.
Any way the worst period was the early disco days where the music featured electronic instruments with a lot of HF content forcing companies like Mac and Infinity to go to line arrays for better power handling above 4 KHZ. Something Bozak had been doing for years. Bozak developed new tweeters to extend their response. Some started using the horrible indestructible piezo tweeters to keep a lid on things. People found that AR speakers could take 3 times the power in the bass but when applied to higher frequencies destroyed tweeters, too. So new designs were created and new HF drivers used. Fluids were used in the gaps to try to dissipate the heat but the tweeters lost their soul that way.
I would guess by the 80's or 90s speakers were better capable of handling power across the spectrum. Thats when the fake power ratings again began. If a woofer could take 80 watts RMS, and a mid 80 watts and a tweeter 60 watts, we will just add them all together for a 200 + watts. Or most music only have 6 db peaks anymore so if speakers can handle 75 watts will say they are rated to 300 watts. Some woofers are rated at or above free air resonance. So that means the bottom octave is not included and where low bass can cause a woofer to exceed its excursion limits.
Thats how you get speakers rated at 1000 watts but when you powers them with 400 to 500 watts with music concentrated in a limited area's the drivers fail today. You always want to know the RMS power handling of each driver and the insertion loss for each driver of a crossover to make an intelligent answer as to the size of the amplifier you choose. Plus you need to know what type of protection the amp employs for itself and if any for the speaker.
You just can't be happy with a speaker with. a 86 db sensitivity and a lot of power when something fails when you are having a party or listening to powerful music seriously. So the best advice I can give is buyer beware, by more efficient speakers, and listen in moderation. What do I mean by more efficient. 94 to 96 db 1 watt 1 meter. Then choose an amp with adequate power for the peaks you want to produce with in the speakers capability. Yes that means bigger speakers or sometimes multiple subs. Give me a pair of Klipsch Cornwalls or Forte's and nice little Mcintosh 7100, 754, 122, etc and I would be happy. Or some of the JBL DD series. An older pair of XRT 22 or 290's would be great but now you need the 500 watt amps with Power Guard to keep a lid on every thing.
My speakers are 95 db efficient and rated at 100 watts RMS, I use 200 with Power Guard. Never a failure in many. many year. But then my average listening is only 4 watts with 20 watt peaks occasionally in stereo mode. About the same with higher peaks for HT model but with 7 channels. The rears and sides at about 10 watt peaks.
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whoaru99
Epic Member
The whole point is why the myth of underpower lives on.
A voice coil never burns/opens from under power. It is always too much power either peak or long term/average. The voice coil doesn't know clean or dirty, it only knows too much or not too much
I simply go very easy on the volume, and work within physical limitations of the system.
I think as a rule this will keep my gear safe, don't recall any disastrous events with tweeters, tho a few woofers with aging surrounds have let go.
I think as a rule this will keep my gear safe, don't recall any disastrous events with tweeters, tho a few woofers with aging surrounds have let go.
Do you really think the only difference was the 3 dB increase from 100 to 200 watts?
That is why I mentioned the 545 earlier, if you would have compared the 2 Adcoms I think you might have come to a different conclusion.
Edit: What whoaru99 said.
damacman
Resident Psycho
And there's the rub. It would be nice if collectively we could all agree on a paragraph of verbiage that explains this in laymen's terms which folks can agree on and understand.
PPstereo
Super Member
Can one ever truly recreate a Who concert
I read your write up above. Excellent in depth explanation of designs and reasons behind various failures.
I also suspect one would need a massive listening room to try and get a natural sounding Who concert recreation in house. And I'm not that lucky.
But yeah no doubt it would need allot of air moving.
I was lucky enough to stumble on a mint RCF FL21N451. I keep kicking around the idea of grabbing another to make some massive end game 3 way speakers all active amped.
Who knows... no pun intended lol
I was working on a Sansui 9090 receiver, 120W a channel I think. The new transistors on the driver board went into high frequency oscillation (bias needed to be higher) which I saw for a moment on the oscilloscope. It went rail to rail and indeed fried the "100W" piezo tweeter in my test speakers. Easily the overpowered rule! Why piezo tweeters? They fit the openings in the Realistic Minimum metal %" two ways perfectly and I could hear some of the treble while testing gear. I have profound high frequency hearing loss that peters out at 3kHz. Those Realisitics' woofers long ago had the surrounds rot and have 100W rated Faital drivers.
G.D.T.R.F.B.
Active Member
I recently hooked up 750W RMS amps to 120 W RMS speakers (they are spec’d down to 58 Hz and I was running the 50 Hz high pass from my NHT SA-2 sub amp) and slowly crept up the volume(once it was already loud 
). I probably turned it up louder than 97.8% of the people on here would be willing to. I’m pretty sure I found “the very fine line”. The clarity and loudness blew my mind. Yeah, I know.
). I probably turned it up louder than 97.8% of the people on here would be willing to. I’m pretty sure I found “the very fine line”. The clarity and loudness blew my mind. Yeah, I know.
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Cogito
Well-Known Member
But it's NOT a myth, as my example points out. The ADCOM amp was far more capable of providing the power that I needed for the given output compared to the Pioneer amp that was obviously pushed beyond it's RMS ratings into clipping. It is well known and demonstrated that when many types of amps (Mostly solid state) clip, they can send for a brief period of time, many times more power than their rated output. Conventional tweeters, with their super thin and light voice coils are particularly sensitive to destruction as compared to the relatively heavier and robust woofer voice coils.
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