"Tsk, tsk. Of course a driver doesn't commit suicide:)!
That, exactly that, was the question: i.e. in other words "what upstream element do you think caused the damage".:
Gregm: Your statement seems a bit odd when indeed I did suggest that the amp or preamp might have passed DC to the speaker. |
Changster,
Just get a pair of ATC 100ASL and you won't be blowing midrange anymore.
There is a good reason why large three ways with the accuton mid use TWO midranges! |
Speaking of "ceramics", heard the latest Marten speakers with 4 built-in passive rear woofers in the Vitus room at CES. They are ridiculously expensive in the US, but contributed to one of the best sounding rooms at the show, IMO. They were being driven very well by a higher current, lower wattage Vitus integrated amp and they were absolutely great, IMO. |
Speakers don't blow up because of "amplified distortion which causes the speaker piston movement to become non linear" but rather clipping allows power to defeat the crossover point and burn the fine coil and leads, similar but different to how a diode only allows power to continuously flow in one direction but will allow pulsed transients to flow in the opposite direction. This illustrates the "minor exception" factor.
Drivers exploding on the other hand usual do so if they are of a high hardness material and resonance node is excited at high power, or if their excursion is exceeded and the air load or suspension puts the diaphragm under additional stress. The T&P drivers all have notable resonance nodes as dictated by the material though they are mostly outside their intended crossover range. The amplifier may have been responsible possibly too. |
I've had the same thing happen with my Kharma too, but I believe there are a couple of mitigating factors...
1) Kharma midrange drivers are virtually connected directly to the Amp (whereas the bass and tweeter drivers are linearly crossed-over). This makes the fragile ceramic cone on the midrange driver relatively exposed! Conversely though, its the very reason why the Kharma midrange sounds so fantastically neutral and natural.
2) The Kharma drivers need plenty of run-in before playing at high SPLs. I'm guessing that pair of Exquisite Reference units weren't thoroughly run-in. With high SPL and a dynamic track, I'm not surprised the cone broke up, probably like a crushed egg-shell :) |
Accuton/Thiel makes thousands of ceramic drivers each year for dozens of speakers. What is particular about Kharma that makes them susceptible to failure? Is it cross-over design or in-house modifications?
I would not jump to the conclusion that this is an inherent property of ceramic drivers at all. We are dealing with pure anecdote, and no one has mentioned any other speaker. Even if someone did, it still would not necessarily indicate a systemic design flaw. I would agree that what Agyro dealt with from Kharma is absurd and absolutely unacceptable.
On another note, many drivers, regardless of material, may fail under the correct (?incorrect?) conditions. They just do not make such a dramatic statement. Leave your speaker grills on, folks, or wear protective goggles. |
No, it's just a Kharma thing. Avalon and Marten both use ceramic drivers and I haven't heard of any similar widespread issues with them. |
"At this type of price range I would expect so much more."
At any price range, perhaps a tendency for drivers to explode (!) should instill caution in the heart of the buyer ;)
John |
Wow I feel like I opened up a can of worms here.
I don't like inferring things, but is this a property of most ceramic drivers, or is it the enginnering behind the speaker? I guess I can't rule out upstream either like Jtinn said.
I went to another shop that used to sell Kharmas and he said they used to have the same problems of the ceramic driver shattering.
At this type of price range I would expect so much more. They should be indestructable. |
Jtinn: It is always upstream. The driver does not just fail. Tsk, tsk. Of course a driver doesn't commit suicide:)! That, exactly that, was the question: i.e. in other words "what upstream element do you think caused the damage". In this case, probably the power. Most Theil & partner drivers are spec'd up to 100W max power... |
Yup, listen to this great kharma story:
In August 2004 I bought the Kharma 3.2! In September 2004 one of the ceramic drivers blew up due to excessive power.
Kharma charged me 500E for a new one. BUT the new driver they sent me was slightly bigger than the previous one!!!!!!!!Resulting in the driver being around 3mm out of the cabinet!!!!
I send an email to kharma and responded that "Accuton changed the ceramic driver size without informing us"!!!!
Can you believe this? And why didnt they tell me from the beginining then?
So they proposed I pay for one more driver so I have a matched pair!!!!!
It is the worse service I have had from any company ever!!!
A friend of mine also blew, both of the drivers in his kharma 3.2.
* For anyone doubting the above I have kept all the emails with kharma* |
The Kharma Exquisite Reference is an excellent speaker. It can truly portray that sense of scale. Unfortunately, Kharma is too much money in the US, which I think is a by-product of currency and importation costs.
Aren't all ceramic drivers made by Accuton/Thiel? Who else makes them?
I think the key to a speaker with a ceramic driver is to have a woofer which properly balances the midrange and tweeter. |
I think there are better brands then Kharma that use ceramic drivers Marten design maybe. But whatever you are going to decide I think you are a "hero" in my book already for owning the best "in my book" amps in the world. |
If the amp or preamp pass DC current to a speaker, it can likely cause the drivers or a driver to blow.
Having owned Kharmas and been a past retailer for them, I have dealt with this many times. It is always upstream. The driver does not just fail. |
Jtinn, Buff - The Soulution preamp was set at "50" if I remember. I highly highly doubt this was over 115db. Maybe 100db, I'm not sure. Jtinn, what do you mean by the amp pushing DC current to the speakers?
Mtdking - were they the ceramic midranges that blew up on you? Was it like what happened to me, where the ceramic cone shattered into pieces? |
I've had ceramic mid - woofers break in shipping. I returned a pair of speakers in factory road cases.
later I got an email saying the woofers were broken and I thought they were talking about a burnt voice coil (which still didn't make sense because I would have heard that).
Finally they sent a picture both had shattered and the metal grills covering the drivers looked fine. The cabinets which were high gloss black also looked unharmed.
PS these were not Kharma's but... |
Having had 2 Kharma drivers blow up on me also, I gave up and after they were fixed and I sold them. I then had Avalon diamonds and never had any problems and with the same amps.
Find another brand is my best advice and one that doesn't have ceramic parts. That what I did and I never have to worry about any of that. |
Something just doesn't sound right here.A 40something grand loudspeaker explodes a driver during an audition. |
Maybe the Kharma sub would eliminate the problem by removing the suspect low-frequency/s. |
If you were playing over 115 db, you possibly over drove the midrange. If not, my guess is the preamp or amplifier was sending DC to the speaker. |
The woofer was overdriven. Ceramic drivers are very stiff, and if the force of the pistionic motion is greater than the woofer can handle it breaks and shatters. This happened to me once and it was not a factor of downstream electronics or distortion, but a failure to keep the volume control at proper level not to damage speakers.
They do sound quite phenomenal, but like anything have a breaking point.
Good luck and happy listening! |
