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Epifani web page cabinet compatability warning.

#102
Again, they essentially claim that their own amps will not cause the same problems or even be susceptible to user error. I'd like to know if that's what they really meant, and if so, how they achieved that? And what makes them privy to such deep technological understanding that their competition is too dim to understand or implement?
 
#105
Even though I'm one that's hammering on them a bit, just to be fair, it's not like they are running ads or building a campaign around this. It is just a blurb on a website. A little cheezy and IMO misleading, yes, but not a huge deal IMO (like the Accuswitch fiasco mentioned above).
 
#106
USAJO said:
What about the DC charge part of the bulletin. Can the amp in question be allowing this to happen damaging the speaker?

It is stated there are many EE's here who have agreed with Bill F. That is not the same as saying all EE's agree. Is it a slam dunk? Do all EE's agree with this? If so I can't imagine how Epifani would make such an uneducated statement. I could make it because it is all I ever heard but I'm not an EE. Do all EE's agree or not?

I'll continue using the cabs because they sound great to me. But geesh, I am stunned that they could issue such a statement if it is so incorrect.
Click to expand...

My read on the Epifani statement was somewhat different than several people have taken. The wording seems poor, but I took their warning to mean that individuals are trying to use amps that have too low a power rating and are maxing the gain and volume on the amps to get the volume they want from the speakers. Low powered amps may not cause excessive speaker excursion when maxed out, but they could cause components in the amp to overheat and fail, leading to conditions that could lead to speaker failure. The amp itself may still function despite some components failing.
 
#107
Although i am a happy 502 owner/user I remember being warned off of Epi cab's specifically the 3X10 because they blew drivers by my tech guys who saw more than a few in the shop.Now this was early in the history of Epi cabs and long before they made amps so what with and how they were being powered may have had a lot to do with it.
 
#108
Out of curiosity, who makes Epifani's speakers? Eminence? Eminence is an extremely popular speaker that is used in a ton of bass cabinets. With the exception of their extended range drivers (used in ACME cabs and these are far and few between) I would assume that they have a pretty low failure rate when you look at the overall big picture.
 
#109
One of the things missing in this discussion was the links posted at the bottom of the disclaimer.

I have a feeling that the drivers in question are the high frequency components. i.e. the tweeters.

I suggest that everybody take a quick look at the JBL link which might explain what I'm thinking that they are referring to.
[Invalid or Expired Link Removed]

I do think that it's kinda comical that there seems to be a sort of witch hunt going on citing a diabolical plan to sell more amplifiers.
 
#111
It's only comical if you think people don't do that sort of thing all the time. Also, I remember a couple of years ago I was caught up in one of those over/underpowering debates here, and just to make a point I Googled for any links that would support the existence of underpowering as a "real" problem- and that JBL link was one of the only credible ones I could find (the rest were from car audio installers, or people just repeating anecdotal stuff on forums). My point is that I suspect Epi came up with a "theory" and then went and Googled for links to support it, which is not really good science or engineering.

The fact that they chose to use such vague, poor language, which doesn't seem truthful or scientific on the surface, is what spurs people's cynicism. Not so comical IMO.
 
#112
Jerry J said:
One of the things missing in this discussion was the links posted at the bottom of the disclaimer.

I have a feeling that the drivers in question are the high frequency components. i.e. the tweeters.

I suggest that everybody take a quick look at the JBL link which might explain what I'm thinking that they are referring to.
[Invalid or Expired Link Removed]

I do think that it's kinda comical that there seems to be a sort of witch hunt going on citing a diabolical plan to sell more amplifiers.
Click to expand...

Thanks for posting the link.

BTW: I also agree with your final point, in that, I don't think any reputable company would use the tech bulletin as a method to boost their amp sales or disparage a competitor's amp.
I've never seen anything to indicate that Epifani is a disreputable company.
 
#113
Jerry J said:
One of the things missing in this discussion was the links posted at the bottom of the disclaimer.

I have a feeling that the drivers in question are the high frequency components. i.e. the tweeters.

I suggest that everybody take a quick look at the JBL link which might explain what I'm thinking that they are referring to.
[Invalid or Expired Link Removed]

I do think that it's kinda comical that there seems to be a sort of witch hunt going on citing a diabolical plan to sell more amplifiers.
Click to expand...

That's one thing that's not clear. What drivers are they talking about? Are they seeing lots of blown LF drivers or HF drivers. The JBL article predominantly relates to HF drivers.
 
#114
From Epifani's website with reference links they included with the original tech bulletin (Bolded)

News
WARNING! - Epifani cabinet compatibility situation
Dear Epifani cabinet owners...

We've been documenting our speaker repairs and have noticed an alarming coincidence. Certain bass specific amplifiers (as opposed to pro audio type amps), none of them Epifani, when used in conjunction with our cabinets tend to blow drivers at an alarming rate. To put this into perspective, less than 2% of the driver failures we repair or replace are blown by people using Epifani heads. Ironically, some of the failures have been operator abuse and the operators are Epifani employees! That's the quality assurance team hard at work.

With regards to the other 98%: We do not know how the customers run these amps, whether or not they have sufficient technological knowledge to operate the amps within the manufacturer's specified limits, how the owners of these amps maintain or care for their equipment nor do we know if these amps are exhibiting symptoms of failure - manufacturer defect, design related or otherwise. What we do know is that they are either void of adequate output protection and discharging DC voltage or emitting Square Waves to such a degree as to cause driver failure. It could be as simple as the operator under powering the cabinets - in other words making too much of a demand on the amplifier thereby putting the amp into a position of clipping (square wave). Extended exposure to square waves will blow any driver. (BTW - this is not like the harmonic distortion guitar players get from their tube amplifiers.)

All speaker manufacturers can open a blown driver and, by looking at the voice coil, determine whether or not the mechanical functionality of the driver was compromised through manufacturing defect or by abuse. The drivers we have been noticing have been damaged most often by a burnt voice coil. An amplifier can burn a voice coil by emitting square waves (clipping distortion) or by releasing DC Voltage which overheats voice coils. A well designed amplifier has adequate output protection which prevents DC Voltage from damaging a driver. A well designed amplifier will only emit square waves when pushed beyond the limits of it's design.

Our advice is to make sure that you have adequate wattage to power our (or any other) cabinets. Be wary of wattage specs. Some amplifier manufacturer’s quote specs a 1 kHz not at full bandwidth. They quote specs at peak power but not at continuous power - all in an effort to advertise larger numbers.


At Epifani we spend considerable time and expense in designing our amplifiers. An unusual amount of time is spent on designing amplifier circuit boards that allow for high power levels and serious output protection. We've been at the forefront of Class D amplifier implementation and have learned valuable lessons about high power output protection. We cannot speak for other manufacturers who may be new to Class D amplifier integration. We will continue to honor our warranty and replace for free any drivers that show manufacturer defect. We will charge standard replacement costs for drivers that are blown out of the parameters of our warranty.

Feel free to call us before you make an amplifier or speaker purchase. We'll do our best to help you pick the right components for optimum compatibility.

Thanks - The design team at Epifani...


To learn more check out these sites:
http://www.colomar.com/Shavano/recone.html
http://en.wikipedia.org/wiki/Square_wave
[Invalid or Expired Link Removed] download the Low Power doc.
Click to expand...
 
#115
I don't have time to get into details at this point but as an amplifier and speaker system designer (in the hifi business) I agree with BFM 100% on the technical bits of this issue.

Burnt voice coils are caused by one thing: More power than they can dissipate. The waveform is irrelevant. A lot of the confusion comes from the fact that an amp driven into clipping produces more than its rated power, so there are instances where clipping a (say) 400W amp into a 500W rated cab can damage a voice coil. It's important to realize that damage is not a function of the waveform, it's a function of the power incident on the driver. Putting 600W into a 500W rated speaker will damage it, regardless of whether it's totally clean or heavily distorted.

I don't think that Epifani are doing anything underhanded here, though. There are a lot of otherwise knowledgeable people in the audio business that don't have a good handle on the mechanics of speaker damage.
 
#117
Have you read the [Invalid or Expired Link Removed] which Epifani suggested for further reading?


The additional power generated by overdriving amplifier is rich in harmonics (distortion). These harmonics can be particularly dangerous to high frequency drivers.


Hmmm...

I HIGHLY suspect the blown dirivers are tweeters if Epifani's logic is actually right.
 
#118
"We've been documenting our speaker repairs and have noticed an alarming coincidence. Certain bass specific amplifiers (as opposed to pro audio type amps), none of them Epifani, when used in conjunction with our cabinets tend to blow drivers at an alarming rate. To put this into perspective, less than 2% of the driver failures we repair or replace are blown by people using Epifani heads. Ironically, some of the failures have been operator abuse and the operators are Epifani employees!"

What % of epifani cabs are run bu epifani heads? without that figure the 2% is an irrelevant number that has no meaning. If only 1% of epifani cabs are run by epifani heads than their ehads blow speakers 200% of the time ;) (Read in Ron Burgandies voice!) Its Science.


I don't know enough to comment either way. However, in my experiance I have seen many cabs blow with a 400 watt clipping amp and on the other hand I run 700RMS watts into a 350RMS cab all night almost at limit with no problems.
 
#119
Jerry J said:
I suggest that everybody take a quick look at the JBL link which might explain what I'm thinking that they are referring to.
[Invalid or Expired Link Removed]
.
Click to expand...
The key phrase in the JBL treatise is "damage the high frequency components", ie., midranges and tweeters. No one in the engineering community disputes this fact. The problem here is that woofers are not high frequency components.
 
#120
The former owner of my totally lovely Epi 2x10 NYC cab toasted the tweeter and got a new one (and crossover) from Nick. In fact, I believe he had 2 of these, and toasted the tweeter in both.

I haven't had a single issue with the cab. Great great 2x10, even if it IS 58 freakin lbs! I give it a workout. :bassist:



It give me one two!!!
 

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