Wayne, you need to go work in a consumer electronics service department for a week or so. See how many head-bangers bring in speakers for repair, how many of those speakers have dead tweeters, how many of those tweeters have open and blackened VC's, failed adhesive from overheating, etc. The typical use case is 1) domestic environment 2) preference for extremely loud and compressed "music" 3) low budget 4) under-powered amplifier driven into sustained hard clipping 5) inexpensive speakers built with cheap tweeters "engineered" to produce normal volume levels with normal energy/frequency distribution. The clipping increases the HF content, which passes through the single-capacitor "crossover" into the tweeter's VC, which gets extremely hot, burns the former, softens the adhesives, and eventually fuses. This is incredibly common.
In worse cases the woofer VCs also overheat enough to loosen the adhesive and the coils start to rub on the magnet assembly.
You just can't turn copper that color without a lot of heat.
In worse cases the woofer VCs also overheat enough to loosen the adhesive and the coils start to rub on the magnet assembly.
You just can't turn copper that color without a lot of heat.
I did find that paper as a pdf available through a search of older JBL papers but for some reason the url got really long and the site deleted it?
A.wayne,
So your saying that when we see a burned voicecoil what is that failure mode? I'm not saying a rubbing coil but an actual burned one. Seen it in plenty of dome tweeters and some cone drivers. Ask any car speaker manufacturer what the largest failure rate is and it will be burned voicecoils.
I am not suggesting horn loaded speakers here and that is another case all together. I am saying that a domestic small format speaker pushed hard will fail in two ways typically, a failure due to over excursion or a burned coil from exceeding the coils heat dissipation capabilities. When Precision Econowind specifies a maximum power handling rating for one of my voicecoils how do they determine that? The failure mode is the overheating of the insulation of the wire. how hot is that melt point?
A.wayne,
So your saying that when we see a burned voicecoil what is that failure mode? I'm not saying a rubbing coil but an actual burned one. Seen it in plenty of dome tweeters and some cone drivers. Ask any car speaker manufacturer what the largest failure rate is and it will be burned voicecoils.
I am not suggesting horn loaded speakers here and that is another case all together. I am saying that a domestic small format speaker pushed hard will fail in two ways typically, a failure due to over excursion or a burned coil from exceeding the coils heat dissipation capabilities. When Precision Econowind specifies a maximum power handling rating for one of my voicecoils how do they determine that? The failure mode is the overheating of the insulation of the wire. how hot is that melt point?
This has nothing to do with our discussion , i never said speakers cant be burnt, plus cheap speakers burn faster than gasolene ...
Are you guys kidding me , we are talking about speakers in normal operation , nothing about them being burnt proof , using this line of thought we can say the same thing about amplfiers , well after burning them up ...
Play your speakers as loud as you do when listening , did you melt them , burn the coils , heard VC induced distortion?
Report ...
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a.wayne,
I am not suggesting that we burn up a bunch of speakers, or that it happens all the time, I was really trying to answer the question of do we need to consider the heating of the voicecoil and I do think it is an issue for any designer to consider. There is heating happening in a dynamic way following the impulse response needed to reproduce whatever music we are listening to. It may only last a very short time or it may be longer term if you are listening at elevated levels. When I am listening to rock and roll and even some Jazz I have a tendency to crank it up, it I am just playing music for background of course I don't do that.At the same time to say there is no temperature rise and impedance changes caused by fast transients with wide dynamic range just doesn't match my understanding of what is going on. In PA of course we talk about power compression but I do believe that it also happens in a domestic speaker at higher spl levels.
I am not suggesting that we burn up a bunch of speakers, or that it happens all the time, I was really trying to answer the question of do we need to consider the heating of the voicecoil and I do think it is an issue for any designer to consider. There is heating happening in a dynamic way following the impulse response needed to reproduce whatever music we are listening to. It may only last a very short time or it may be longer term if you are listening at elevated levels. When I am listening to rock and roll and even some Jazz I have a tendency to crank it up, it I am just playing music for background of course I don't do that.At the same time to say there is no temperature rise and impedance changes caused by fast transients with wide dynamic range just doesn't match my understanding of what is going on. In PA of course we talk about power compression but I do believe that it also happens in a domestic speaker at higher spl levels.
This discussion started after you postulated that vc heating is less of a problem under normal conditions, than crossover capacitors operating close to their maximum voltage. When I explained why you where wrong, I may have forgotten to mention that I have never seen a loudspeaker where the cap would give out before the driver. Never. Anybody out there who has? We are not talking about age related failure here, but dielectric break down. Before dielectric break down occurs, a capacitor will pretty much do what it always did.
It is very much different for drivers. Way before they break down due to thermal issues, vc heating will start to impact on performance. Compression always, xover misalignment on top of it in case of passive xover. And yes, even in domestic situations, drivers get fried.
No this conversation started from the STRAWMAN argument of VC INDUCED DISTORTION , many replys yet you have not posted one iota of data from your personal test ..
Nothing , nada ,
I have seen Electrolytics go Boom bada boom in PA (79) speakers ..
@Hornman,
Again VC induced distortion is an issue , its not an issue in non cheap , properly designed domestic speakers . We looked into this almost 20yrs ago and again recently 5 yrs ago and nada, nothing , i could not objectively or subjectively detect VCID , so Imo it's numero uno strawman argument interjected by those pushing Hornies ...
Vacu = Horny
So its rolls off his lips , yet no proof , he has never measured it , nor experienced it , this with his vast experience. Showing me papers that VCID exist is parcing with semantics , the contrntion is not if VCID exist , the contention is , does it exist enuff to affect domestic loudspeakers ...
Still waiting....
Nothing , nada ,
I have seen Electrolytics go Boom bada boom in PA (79) speakers ..
@Hornman,
Again VC induced distortion is an issue , its not an issue in non cheap , properly designed domestic speakers . We looked into this almost 20yrs ago and again recently 5 yrs ago and nada, nothing , i could not objectively or subjectively detect VCID , so Imo it's numero uno strawman argument interjected by those pushing Hornies ...
Vacu = Horny
So its rolls off his lips , yet no proof , he has never measured it , nor experienced it , this with his vast experience. Showing me papers that VCID exist is parcing with semantics , the contrntion is not if VCID exist , the contention is , does it exist enuff to affect domestic loudspeakers ...
Still waiting....
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Wrong, this is what I was referring to. And while you were doing this, as far as I recollect, you jumped on a bandwagon started earlier by Richard Marsh, but you may have misunderstood what he ment.
Please study some more, this is a good starting point http://www.klippel.de/measurements/nonlinear-distortion/compression-of-fundamental-components.html
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Prove it , measure the voltage at your listening level and then measure the speaker accordingly , report if you can objectively or subjectively prove VCID , at your listening level. I gave you no conjecture , we tried to measure it and tried listening sessions to detect, even when attempting to abuse , it was the amplfiers more in trouble than the speakers ...
More spin and conjecture , i want to see your data , i mean this is so widespread you must have experienced VCID ...
ps: you should read what you post Vacu and stop clouding.
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Me. That's one of the design features of the NHT M3.3- the drivers are difficult to kill because the crossover will give out first. Two 100V electrolytics, spectacularly blown. A few minutes with a soldering iron and they were singing again.
My suspicion is that these VC problems occur when the system is badly distorting - even though I like to run my playback loud, I have zero interest in hearing distortion, so I always adjust the volume to just below onset of audible strain, in lower powered situations. I would suggest many people are trying to derive subjective "energy" from the track, when they keep winding up the volume, way past sensible levels ... IME, the "energy" is automatically there when the playback is completely clean - but if there is a dead or flat quality to the normal sound then the only solution seems to be to "pump up the volume", trying to extract some "excitement" from what you're hearing - and components fail.
Sy,
Not that I have ever used electrolytics in a crossover, only PP and some small PS, I have seen them in many older speakers like some old Altec's I have. What do you attribute the ba da boom of those electro's to? To much voltage or just cheap components? I never use anything less than 100V rating and a few were higher rated than that, but just cause I got those for free as samples. I don't think you could possibly hurt the networks on my speakers without some serious power and by then the speakers would be toast.
As I said earlier I have never used a single cap by itself, they just never fall right on a value I seem to need and so have multiples in parallel to get the values I want. Not sure it would matter in the shunt position but in series perhaps with enough power it would be a problem.
Did you replace the electro's with another of the same or change it for something better?
Not that I have ever used electrolytics in a crossover, only PP and some small PS, I have seen them in many older speakers like some old Altec's I have. What do you attribute the ba da boom of those electro's to? To much voltage or just cheap components? I never use anything less than 100V rating and a few were higher rated than that, but just cause I got those for free as samples. I don't think you could possibly hurt the networks on my speakers without some serious power and by then the speakers would be toast.
As I said earlier I have never used a single cap by itself, they just never fall right on a value I seem to need and so have multiples in parallel to get the values I want. Not sure it would matter in the shunt position but in series perhaps with enough power it would be a problem.
Did you replace the electro's with another of the same or change it for something better?
The speakers had been badly abused at a party by the son of an NHT distributor, then sent back to NHT. So... presumably very high volume. And it's easy to do, they sound pretty effortless at high SPL. My luck, NHT sold me the speakers as-is for an insanely low price. $5 and 15 minutes of my time later, they were good as new.
I doubt that they were cheap caps (this was not a cheap speaker at retail), but "upgrading" them would be a poor idea. Ken Kantor used exactly the appropriate parts in his designs and I don't pretend to know better than he. Eventually, the caps left the circuit as I converted the speakers to multiamp, but I lived with them stock for several months before doing my rebuild.
I doubt that they were cheap caps (this was not a cheap speaker at retail), but "upgrading" them would be a poor idea. Ken Kantor used exactly the appropriate parts in his designs and I don't pretend to know better than he. Eventually, the caps left the circuit as I converted the speakers to multiamp, but I lived with them stock for several months before doing my rebuild.
What I find very amusing is that so many of people insisting that electronics are not part of the "problem", 
, use multiple amplifiers to drive their speakers - in one fell swoop they have eliminated, bypassed a huge swag of the potential issues causing quality problems ... and yet they continue to harangue people who manfully try to get conventional audio setups, one amplifier only, to sound reasonable, when they say amplifiers make a difference -- hoo, boy!!
, use multiple amplifiers to drive their speakers - in one fell swoop they have eliminated, bypassed a huge swag of the potential issues causing quality problems ... and yet they continue to harangue people who manfully try to get conventional audio setups, one amplifier only, to sound reasonable, when they say amplifiers make a difference -- hoo, boy!!
Frenchie ,
JBL :
600 W AES continuous pink noise
Sensitivity: 97 dB SPL, 1 W, 1 m (3.3 ft)
Frequency Range
: 30 Hz - 2.5 kHz
Power Compression:
at –10 dB power (60 W): 0.7 dB***
at –3 dB power (300 W): 2.5 dB
at rated power (600 W): 4.0 dB
@ 60 watt power compression on their bass unit is .7db, consistent with what we found 20 yrs ago, when testing RMS below 32 watts and consistent also when used in typical domestic hi-fi, VCID would not be an issue.
60 watts RMS would translate to over 720 watts peak power when used in domestic hi-fi situation. even you head banging nutters couldn't go there ..
You said a voice coil could not reach 150C. That was clearly wrong, and others here have shown you that they can reach >200C.
But never mind, you "measured" voice coil temperature and "proved" it can't happen, so the experiences of others are clearly delusional. It's like those guys who measure amplifiers and prove that there can be no audible differences.
never said that , so go ahead and quote me , should be easy ...
I said never in a domestic hi-fi environment, never said you couldnt burn up a driver , i said at up to 32 watts rms , we could not measure dynamic compression, in your case it must have been 30% thd and no music, possibly PA disco use too , not what we were discussing , read back ...
I said never in a domestic hi-fi environment, never said you couldnt burn up a driver , i said at up to 32 watts rms , we could not measure dynamic compression, in your case it must have been 30% thd and no music, possibly PA disco use too , not what we were discussing , read back ...
Over the years, I have seen a number of otherwise excellent speakers and drivers burnt badly, a good friend of mine has a service shop and all sorts of cases find him.
Burning out Dynaudio drivers is not easy, but some have managed even that.
It seems the deadly combination is a nominally very powerful loudspeaker, capable of withstanding peak programme material of over 300W being driven by some low quality amps. The large power rating misleads people who believe that their 30WPC amp can never burn out that speaker. So they crank the bass pot to + maximum, typically at least +12 dB and often more, and let it rip.
So, in fact, they feed the speaker with clipped signal for hours on end during a party. What's an honest to God speaker to do with so much clipping but burn out?
On Wayne's argument - perhaps he should have said no burnout up to say 16 Vpeak unclipped output signal into nominally 8 Ohms. That's assuming the driving amp is capable of at least rwice that output voltage, so the chances of clipping are reduced.
Burning out Dynaudio drivers is not easy, but some have managed even that.
It seems the deadly combination is a nominally very powerful loudspeaker, capable of withstanding peak programme material of over 300W being driven by some low quality amps. The large power rating misleads people who believe that their 30WPC amp can never burn out that speaker. So they crank the bass pot to + maximum, typically at least +12 dB and often more, and let it rip.
So, in fact, they feed the speaker with clipped signal for hours on end during a party. What's an honest to God speaker to do with so much clipping but burn out?
On Wayne's argument - perhaps he should have said no burnout up to say 16 Vpeak unclipped output signal into nominally 8 Ohms. That's assuming the driving amp is capable of at least rwice that output voltage, so the chances of clipping are reduced.
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