OK let first start of by stating that the Mark Audio drivers are generally a great buy and work very well for what they are intended, and up to this point I have been very satisfied. Now with that being said I'd like to express my displeasure in one of my drivers self destructing after 1 week of playing out of the box, and the second one from the same box being wired out of phase from the other (from the factory not me). Hmmmmm, I've bought several pairs of the CHR-70 as I've built many cabinets for friends and family based on how good this little guy is, now my biggest concern is with the structural longevity of the metal cones. See the one driver that self destructed in fact still works(ie no VC short), and seems to do everything good accept female voice/brass, with this it vibrates and honks like mad. Soooo long story short I pulled it out of my Onken style cabinet and low and behold little stress fractures all around the surround directed toward the center of the cone. Currently the cracks are only 1/8-1/4" long but they are through and through and let air escape and vibrate like crazy on female voice and brass inst. I'm primarily a Jazz listener with some varying degrees of other music played through my systems but never real loud or abusive.
Anyone else have this issue?
Hey Mark Fenlon any ideas brother?
Anywho just a small rant to vent my displeasure, keep rocking.
Anyone else have this issue?
Hey Mark Fenlon any ideas brother?
Anywho just a small rant to vent my displeasure, keep rocking.
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I'd wager that far more of the metal coned drivers have been damaged in handling / installing in cabinets (or could be that's just us ?), but Mark and others have noted issues with both stressing of frames by over-torquing of mounting screws, and at least a couple of incidences of damage from over-driving have been reported.
Some photos might possibly help Mark to guess at the cause?
Some photos might possibly help Mark to guess at the cause?
I had similar issues with the Alpair 10.1. They performed for the first two weeks and then developed stress lines, surround delamination and stopped functioning. I was suprised by the short lifespan given that I've had multiple sets of the Jordan Jx92s' in use since 2008 without problem. Considering the difference in price between the Alpair and the Jordan's as well as the lack of availablity of the Jordan's I'd like to use the Alpair 10's again. I've been watching this forum for user feedback on the Alpair gen 2's before making any further investment.
I also have a set of the Alpair 12's that have been in use for most of this year. They show no sign of the above issues. Perhaps only the first generation of Alpairs had problems.???
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Rick
I also have a set of the Alpair 12's that have been in use for most of this year. They show no sign of the above issues. Perhaps only the first generation of Alpairs had problems.???
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Rick
Hi Guys,
The Gen. 1 drivers used a softer grade alloy. These cones were part hand-made so were more variable in thickness and profile consistency. All Gen. 2, Gen. 3 and Alpair 12 Gen. 1 drivers now use the Multiform cones. These are much stronger. Somewhere on the forum are several posts from members who commented on CHR-70's that have taken allot of punishments and still kept going.
Take a look at this thread as the issue has been covered here:
http://www.diyaudio.com/forums/markaudio/193247-alpairs-arent-woofers.html
A word of caution. No full-range driver can take allot of power. With the benefit of easy make movies, I've had several examples on recent times sent from guys who say they don't over-load the drivers, only to find they do.
Other thing to note is more members are asking me to increase SPL. That means I have to reduce mass, that means power-handling will remain limited. Anyone that's operating a high SPL or small full ranger driver will (or should) know this.
Alpair 10 Gen 2. Its a driver that I've built right up to the limit. Its cone is less than 1000 micron thick. With its trick coil, its strictly a low load driver. Take a look at the Makraudio forum for advice on how to use this driver and other Markaudio driver, there's plenty of comment on various threads.
New Alpair 12 (Gen 2). Many members are asking me to get this driver over the 90dB threshold. I can do this, but again, its comes at a price. You know what this will be.
Its up to you guys. I can start building drivers with more power handling capacity, that's much easier work for me (or any maker) to do. But you'll sacrifice musicality, bandwidth and SPL. Which is it to be?
Cheers
Mark.
The Gen. 1 drivers used a softer grade alloy. These cones were part hand-made so were more variable in thickness and profile consistency. All Gen. 2, Gen. 3 and Alpair 12 Gen. 1 drivers now use the Multiform cones. These are much stronger. Somewhere on the forum are several posts from members who commented on CHR-70's that have taken allot of punishments and still kept going.
Take a look at this thread as the issue has been covered here:
http://www.diyaudio.com/forums/markaudio/193247-alpairs-arent-woofers.html
A word of caution. No full-range driver can take allot of power. With the benefit of easy make movies, I've had several examples on recent times sent from guys who say they don't over-load the drivers, only to find they do.
Other thing to note is more members are asking me to increase SPL. That means I have to reduce mass, that means power-handling will remain limited. Anyone that's operating a high SPL or small full ranger driver will (or should) know this.
Alpair 10 Gen 2. Its a driver that I've built right up to the limit. Its cone is less than 1000 micron thick. With its trick coil, its strictly a low load driver. Take a look at the Makraudio forum for advice on how to use this driver and other Markaudio driver, there's plenty of comment on various threads.
New Alpair 12 (Gen 2). Many members are asking me to get this driver over the 90dB threshold. I can do this, but again, its comes at a price. You know what this will be.
Its up to you guys. I can start building drivers with more power handling capacity, that's much easier work for me (or any maker) to do. But you'll sacrifice musicality, bandwidth and SPL. Which is it to be?
Cheers
Mark.
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Mark,
Excursion up to and including Xmax is by definition supposed to be within the linear range of operation for a loudspeaker, regardless of whether it is designated full range, mid range, woofer or whatever marketeers choose to call it.
Operation of a loudspeaker in the linear range of operation should not cause damage.
In post #44 of the “alpairs-arent-woofers” thread you link, you say:
“So I'd still urge guys to adopt a practical observational approach when using Full-rangers. For example, on a Gen 2. Alpair 10, ideally the cone shouldn't move more than about 3 to 4-mm (1 way) on a big roll of drum, or other similar dramatic moment in the music. For regular LF beat music, better to work on around 2-mm a guide.”
I agree observation of excursion is a good way of preventing cone damage.
That said, the Gen 2 Alpair 10 specs list an Xmax of 8.5 (one way) which means the cone should be able to do 17 mm peak to peak movement without causing mechanical damage.
You don’t list the Xmech (AKA Xlim) figure on the specification sheet.
If you are recommending the cone should not move more than 4-mm (1 way) safely on transients, which is only 8 mm peak to peak, you should revise the PDF showing Xmech as 4 mm and perhaps not bother listing an Xmax of more than double that which you seem to think may cause cone damage.
Art Welter
Excursion up to and including Xmax is by definition supposed to be within the linear range of operation for a loudspeaker, regardless of whether it is designated full range, mid range, woofer or whatever marketeers choose to call it.
Operation of a loudspeaker in the linear range of operation should not cause damage.
In post #44 of the “alpairs-arent-woofers” thread you link, you say:
“So I'd still urge guys to adopt a practical observational approach when using Full-rangers. For example, on a Gen 2. Alpair 10, ideally the cone shouldn't move more than about 3 to 4-mm (1 way) on a big roll of drum, or other similar dramatic moment in the music. For regular LF beat music, better to work on around 2-mm a guide.”
I agree observation of excursion is a good way of preventing cone damage.
That said, the Gen 2 Alpair 10 specs list an Xmax of 8.5 (one way) which means the cone should be able to do 17 mm peak to peak movement without causing mechanical damage.
You don’t list the Xmech (AKA Xlim) figure on the specification sheet.
If you are recommending the cone should not move more than 4-mm (1 way) safely on transients, which is only 8 mm peak to peak, you should revise the PDF showing Xmech as 4 mm and perhaps not bother listing an Xmax of more than double that which you seem to think may cause cone damage.
Art Welter
Attachments
I had an issue with the Alpair 12 as well. Had them breaking in for a few weeks and they developed stress fractures on the cone. FWIW, no other driver I've owned has done this (Jordans included). I promptly returned them and got my money back.
Who wants to to worry about blowing the drivers while turning it up? To each his own.
Edit: Agree with Art above. The big attraction of the MA line and the Jordans is the large X-max, which in the case of the Jordans is not out of line with the specs.
Who wants to to worry about blowing the drivers while turning it up? To each his own.
Edit: Agree with Art above. The big attraction of the MA line and the Jordans is the large X-max, which in the case of the Jordans is not out of line with the specs.
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1000 micron is like, one millimeter?
For the rest I have to agree with Mark that it is horses for courses.
vac
Hi Art, (Guys),
Your making assertions that aren't correct.
I'll be 100% clear about this: No Full-Range maker designs their drivers to operate at X-Max for sustained periods. Very few commercial domestic makers (if any) will guarantee their drivers to operate at X-max for sustained periods. If you take ANY Full-ranger or typical smaller driver close to its X-Max regularly, you'll either break the cones, or stretch the suspensions. Either way, the drivers will soon out of operational spec.
Most commercial testing operates drivers for up to 100 hours at X-max. If the driver holds up, it passes. For Full-range drivers, the test loads are much lower. Typically, testing is done over longer periods (250 to 500 hours) at up to 25% of X-max.
Markaudio drivers are capable of operating to their quoted X provided its for Non-Linear loads. On most music, there will some output that Full-Range driver designers call "snap load", or "shock load". For Full-Designers, there's 2 choices; We can choose to ignore the shock load (coil moves out its gap), or we can design the power-train with an extended coil design to dynamically balance it and thus record the shock load. But we only do this for non-linear (not regular) loads due to the need for wide band emittance which demands a low mass design. All Full-range designers have make a judgment on what mass penalty must be paid for getting the cone to emit a wide band.
Cheers
Mark.
Your making assertions that aren't correct.
I'll be 100% clear about this: No Full-Range maker designs their drivers to operate at X-Max for sustained periods. Very few commercial domestic makers (if any) will guarantee their drivers to operate at X-max for sustained periods. If you take ANY Full-ranger or typical smaller driver close to its X-Max regularly, you'll either break the cones, or stretch the suspensions. Either way, the drivers will soon out of operational spec.
Most commercial testing operates drivers for up to 100 hours at X-max. If the driver holds up, it passes. For Full-range drivers, the test loads are much lower. Typically, testing is done over longer periods (250 to 500 hours) at up to 25% of X-max.
Markaudio drivers are capable of operating to their quoted X provided its for Non-Linear loads. On most music, there will some output that Full-Range driver designers call "snap load", or "shock load". For Full-Designers, there's 2 choices; We can choose to ignore the shock load (coil moves out its gap), or we can design the power-train with an extended coil design to dynamically balance it and thus record the shock load. But we only do this for non-linear (not regular) loads due to the need for wide band emittance which demands a low mass design. All Full-range designers have make a judgment on what mass penalty must be paid for getting the cone to emit a wide band.
Cheers
Mark.
You are of course absolutely correct. If the motor is linear out to 8.5mm one way, yet the moving parts of the driver cannot accomplish this without damage, then an Xmech parameter needs to be defined, as, like you said, something like 4mm one way.
I tried bringing this objectively and with examples to Marks attention in the "alpairs-arent-woofers" thread but ended up having a bunch of my posts deleted...
Once again Mark, people are damaging your drivers from over excursion. If they cannot operate at the specified Xmax without damage then you need to define the Xmech. It's exactly why the Xmech parameter exists.
Art, iirc, 5thElement posted some comments in that alpairs aren't woofers thread back when it was started. Mark wasn't thrilled with his comment and deleted them. Here Mark can't do that. Mark is right. They're not woofers. And they're full range drivers bound to the same laws of physics as every other full range driver. But I also agree with you that xmech is 4mm and xmax is 2mm based on what Mark has said. Possibly xmech is 8.5 and xmax is 4mm based on what was said.
With that, my EL70s still pump like crazy. They're paper though, so perhaps more tolerant.
With that, my EL70s still pump like crazy. They're paper though, so perhaps more tolerant.
Hi Vac,
Apologies, I keep using my engineering brain. We start with a stock material and use Multifrom which consists on several press processes, we get the final cone mean profile thickness to around 100 to 200 micron (0.1 to 0.2-mm) depending on the calculated power-train mass requirement for a particular model.
Thanks
Mark.
Hi Dain,
If you design your box and driver combo so its near optimal and suitably sized for your room, you'l likely only use about 25% of a driver's quoted X-Max for the majority of music. From what you've written, you'll easily get 10+ years from Full-Rangers.
Cheers
Mark.
I support Mark in one way, having had paper drivers, (not his), damaged by others who ran them continuously overdriving on rock music, even though the amp power was within ratings. The same drivers on classical used at similar levels were not damaged.
I have always understood the manufacturer's ratings were maximum allowable peak, ie intermittent. Traditionally HIFi manufacturers have in the past spec'ed accordingly. and try to maintain sound quality of the peaks. Occasional peaking does not result in fatigue.
But hard rock is not "intermittent", and I think pro drivers recognise this, and design for mechanical robustness, and don't worry too much about what it does to the sound at near maximum levels. (I've put that badly, but you know what I mean). Running close to peak limits all the time will result in fatigue.
KEF in fact in the B110 ensured the cone hit the frame and produced a rattle well before it reached its linear limits. I've reached this on Rock, but never heard it on classical. The B110 is a robust and heavy cone with limited frequency range. I would never expect a very light small driver of 3 or 4 inches to handle rock very well at all.
So I think there is a case for different ratings according to the type of music, or the intended use.
Maybe Mark can devise an additional specification that recognises this. I don't think the suggestion of Xmech does this.
I have always understood the manufacturer's ratings were maximum allowable peak, ie intermittent. Traditionally HIFi manufacturers have in the past spec'ed accordingly. and try to maintain sound quality of the peaks. Occasional peaking does not result in fatigue.
But hard rock is not "intermittent", and I think pro drivers recognise this, and design for mechanical robustness, and don't worry too much about what it does to the sound at near maximum levels. (I've put that badly, but you know what I mean). Running close to peak limits all the time will result in fatigue.
KEF in fact in the B110 ensured the cone hit the frame and produced a rattle well before it reached its linear limits. I've reached this on Rock, but never heard it on classical. The B110 is a robust and heavy cone with limited frequency range. I would never expect a very light small driver of 3 or 4 inches to handle rock very well at all.
So I think there is a case for different ratings according to the type of music, or the intended use.
Maybe Mark can devise an additional specification that recognises this. I don't think the suggestion of Xmech does this.
Hi RJB,
Your comments are objective, thanks for them.
The essential problem for Full-Range (and most commercial limited range) driver designers, is we don't have any control over the use and operation of the drivers. Such is the variety of musical load output placed upon drivers, it has to come down to end-users to recognise the general limitations of driver types.
For example, I' seen Alpair 10's being pushed here by local end users to in excess of 6-mm (1 way) on several dramatic classical music tracks. Very effective at creating the "drama" in the music. I design a driver's power-train with a "long throw" to cater for this aspect of musical performance. But we're talking about a few seconds on drum roll and similar. That's a long way from then being able to play heavy duty beat music with much regularity. There's no way ANY Full-Range driver designer can cater for a near constant heavy LF load.
Hense, no maker of domestic (home hi fi) driver is going to state that their drivers will constantly operate at X-Max without sustaining damage.
All I can do is offer practical advise and hope it helps as many members as possible. I'm caught in a catch 22 trap. My drivers are x'max capable so like all other makers I state the run load. This is within the context of typical "Full Range" applications. Unlike most other driver makers, I do my best to engage with end-users with help and advice on the operation of drivers. A few members keep making assertions that are technically wrong. They assume they know more about driver design and specification than I do. I have err on the side of restraint as I've no wish to create conflict while at the same time, try to help the majority of members with their hobby, not an easy balance at times. On my section, where a member keep making an assertion that is incorrect to point where it potentially mis-leads others, I have no option but to delete.
Cheers
Mark.
Your comments are objective, thanks for them.
The essential problem for Full-Range (and most commercial limited range) driver designers, is we don't have any control over the use and operation of the drivers. Such is the variety of musical load output placed upon drivers, it has to come down to end-users to recognise the general limitations of driver types.
For example, I' seen Alpair 10's being pushed here by local end users to in excess of 6-mm (1 way) on several dramatic classical music tracks. Very effective at creating the "drama" in the music. I design a driver's power-train with a "long throw" to cater for this aspect of musical performance. But we're talking about a few seconds on drum roll and similar. That's a long way from then being able to play heavy duty beat music with much regularity. There's no way ANY Full-Range driver designer can cater for a near constant heavy LF load.
Hense, no maker of domestic (home hi fi) driver is going to state that their drivers will constantly operate at X-Max without sustaining damage.
All I can do is offer practical advise and hope it helps as many members as possible. I'm caught in a catch 22 trap. My drivers are x'max capable so like all other makers I state the run load. This is within the context of typical "Full Range" applications. Unlike most other driver makers, I do my best to engage with end-users with help and advice on the operation of drivers. A few members keep making assertions that are technically wrong. They assume they know more about driver design and specification than I do. I have err on the side of restraint as I've no wish to create conflict while at the same time, try to help the majority of members with their hobby, not an easy balance at times. On my section, where a member keep making an assertion that is incorrect to point where it potentially mis-leads others, I have no option but to delete.
Cheers
Mark.
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This needs to be cleared up a little because the definitions are getting slightly blurred.
On an overhung motor the Xmax parameter typically defines the excursion that the motor is capable of whilst leaving the gap completely filled with the voice coil.
There is one other definition that I am aware of that states Xmax is when the drivers distortion has increased to 10%THD. Under this definition, the motor could still have the gap completely filled with coil but if the mechanical parts of the driver impede the linear motion of the cone then distortion will rise. This happens with the B&W FST drive unit to an extent as the surround is as good as non existent and the distortion of the driver goes up way before the motor should start to lose linearity.
Marks drivers of course don't really fall into the second category and I'd expect they will keep their distortion low, beyond what would be the safe operating Xmech, as the motor should still be pretty linear. Of course keep that 10% THD drive level up at low frequencies and the cone will deform and then things will turn nasty.
Mark is right in saying that they are full range drivers and you are right in saying that they are bound to the same laws of physics as everything else. But along come the T/S parameters as a way of usefully using the laws of physics to quantify how a driver behaves and what its limitations are.
This is where the problem lies. Marks drivers do have large Xmax figures. The motors are linear out to large excursions. If the Xmech happens to be 4mm, this doesn't reduce the Xmax parameter, it's still the same.
It is perfectly possible, using certain motor construction techniques, such as Adires XBL^2 technology, to make motors that have a linear excursion that is downright ridiculous, yet the rest of the driver would be destroyed if driven to these extremes. Here Xmech would be less then Xmax. Doesn't mean much except that your driver will remain linear right up until the point where it explodes, which is actually a good thing, unless of course you're the type of person who decides it's too loud when it starts to sound bad.
I don't think it's too much to ask for really, that Mark defines what the safe repeatable operating excursion capabilities of his drivers are. With that defined there would be no room for confusion on anyones part and it would greatly aid in helping people to design their boxes and it would also help significantly in deciding where and how to cross them to a sub or cross them to a bass driver in a low xover point/shallow slope three way.
I do not understand why this is in anyway unreasonable.
It does do this. It quite simply states that you can drive the driver at the rated Xmech for extended periods of time without causing any damage to the driver. You can use it directly for calculating how loud you can actually play rock music.
Usually people design around the Xmax parameter and design knowing that 99% of the time they will never exceed it. However for the occasional peaks, or perhaps repeated peaks in rock music, Xmax is exceeded, but Xmech is not. There is a degradation of the sound quality when these peaks occur, but because Xmech isn't exceeded the drivers don't become damaged.
In the case of Marks drivers you could easily calculate the max level you can drive rock music too based off of an Xmech parameter. The grey area is actually when listening to something like classical music because of the larger dynamic range you do typically get much louder peaks even if they are few and far between. The peak will drive the loudspeaker beyond its Xmech, and how well it will survive this depends from driver to driver.
Damage in this case would be described by the materials, such as the cone or the surround, going, due to stress, into its plastic region such that it doesn't return to its original shape once the stress is removed. To this end even if you only listen to classical music and only very occasionally push the driver beyond its Xmech you will still damage the cone when doing so. It's just that it might take several hundred of them to cause any noticeable damage and with classical this might take a few years. Either way the Xmech parameter still describes the point where the driver will start to suffer permanent damage once you go beyond it, even if this damage only happens to be extremely minor as to be inconsequential with the right type of music.
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