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Epifani web page cabinet compatability warning.

#121
billfitzmaurice said:
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.
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I understand what you're saying, but I don't recall having read anything in Epifani's blurb that specified whether the problems to which they allude were endemic to woofers, mid-range drivers or tweeters.

It seems that most modern cabinets seem have a tweeter, if not a tweeter and a midrange driver, both of which can be damaged when grossly overdriven, whether by an underpowered amp pushed beyond its limits, or a very powerful amp pushed beyond common sense levels.
 
#122
Jazzdogg said:
I understand what you're saying, but I don't recall having read anything in Epifani's blurb that specified whether the problems to which they allude were endemic to woofers, mid-range drivers or tweeters.

It seems that most modern cabinets seem have a tweeter, if not a tweeter and a midrange driver, both of which can be damaged when grossly overdriven, whether by an underpowered amp pushed beyond its limits, or a very powerful amp pushed beyond common sense levels.
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I agree. Nothing I read in the Epifani web bulletin specified or even mentioned LF drivers or woofers. Their links only refer to things that would damage midrange drivers and tweeters, which would lead me to think that Epifani was concerned with blown tweeter and/or midrange drivers.

Of course, they could have stated that directly in their bulletin to begin with. ;)
 
#123
So, I think we are concluding that the tweeters are blowing, based on the engineering understanding in the group, and in the details provided by the JBL writeup.

If it turns out the woofers are blowing, something is seriously wrong.

Who has a contact or an in with Epifani? Let's find out: Is it woofers or tweeters that are blowing?

My curiosity is high on this, as I just ordered a UL210 from BassNW.
 
#124
I'm someone who has been building my first serious bass gear rig over the last couple of months and have been doing lots of research. I've been looking for lightweight cabs and Epifani was near the top of my list. So I will give you my perspective as to how that bulletin is affecting my purchasing decision.

I actually ran into that bulletin on their website a couple of days ago before running across this thread here. As a prospective buyer, I can say all it did was pretty much push Epifani to the very bottom of my buy list.

I just bought an amp yesterday, and it isn't Epifani. So regardless if this is a marketing ploy or genuine concern, either way I read it it doesn't make me want an Epi as my amp might somehow blow it. I don't recall seeing a bulletin like this from any other manufacturer so it just shakes my confidence in owning an Epi cab and that I would get any warranty service should something go wrong.

Haven't bought yet and I'll never say never but my purchase likely won't be Epi just because of that bulletin. They should really examine their communication skills regardless.
 
#127
May I please refer everybody to a long respected JBL tech note that was geared originally to the OEM's building products with JBL componenets. This basic paper goes back to the 70's IIRC, and recognizes the effects of power differences due to waveform shape.

[Invalid or Expired Link Removed]

Low frequency drivers are damaged by excessive power, otherwise your speakers would blow up every time you turned the volume down!
 
#129
fretster said:
Well well well. The notice has been removed from the Epifani site!
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Thanks for telling us that - I thought I was going nuts not being able to find it! And thanks to Hawaii Islander for posting the notice for us to read. I cannot believe they posted that notice. Also alarming is their apparent misunderstanding of the effects of clipping, underpowering, and square waves. How can one be a reputable amplifier OR speaker manufacturer and continue to perpetuate "ye old clipping myth?"

Well, the notice may have been removed from Epifani's website, but now it's fallout time as that gem will probably remain on Talkbass for sometime to come! :eek:
 
#130
Could someone explain this?



4. What about loudspeaker abuse in normal
operation? Should there be any de-rating of systems to
allow for this?

Yes. JBL defines the following three categories
of loudspeaker application, each requiring an
adjustment of the system's IEC rating:

A. For carefully monitored applications where
peak transient capability must be maintained, a system
should be powered with an amplifier capable of
delivering twice its IEC rating. For example, a studio
monitor system rated at 300 watts can be safely driven
by an amplifier capable of 600 watts output.

Discussion: Careful monitoring is the key here.
High quality music production today demands high peak
factors in the recorded signal. Such peak signals are
normally of such short duration that they hardly stress
the system's components. Thus, the extra 3-dB margin
(times two) of power will result in cleaner overall
operation of the system, with less listening fatigue.

B. For routine application where high
continuous, but non-distorted, output is likely to be
encountered, a system should be powered with an
amplifier capable of delivering the IEC rating of the
system.

Discussion: This case describes the bulk of
sound reinforcement activities. Such systems can often
be inadvertently overdriven, or can go into feedback.
When powered with an amplifier equal to their IEC
rating, the user is guaranteed of safe operation.

C. For musical instrument application, where
distorted (overdriven) output may be a musical
requirement, the system should be powered with an
amplifier capable of delivering only one-half of the IEC
rating for the system.

Discussion: Much rock music is produced at full
output with the amplifier well into clipping, and this is a
matter of musical choice. When an amplifier capable of,
say, 300 watts of undistorted sinewave output is driven
well into clipping, its output power can approach 600
watts! So, Berating the system to one-half its IEC power
will result in safe operation of the loudspeaker.



Epi says they're seeing a lot of burnt voice coils, that's thermal limits being exceeded for whatever reason. Or is it exceeding xlim and shorting out or something? Some here say "it must be the tweeters they're talking about"...we'll see when we all go back to work tomorrow morning. And yes, upon actually reading the article after skimming it, they really would like you to buy an Epi amp....duh.:smug:
 
#131
So everyone who has a non-Epi amp should definitely NOT consider buying an Epi cabinet. Anyone who already has an Epi UL-410 Series II and is powering it with a non-Epi amp should contact me immediately and sell it to me for pennies on the dollar so as to avoid the horrible consequences of blown drivers.:ninja:
 
#132
JimmyM said:
I respect this stance too, but I hate it! The world was built on pointing out the weaknesses of the competition, and quite frankly, I am really bummed that Epifani would choose to make a statement like that with no basis in fact. To me it smacks of scare tactics. I regularly underpower speakers and it never hurts them, even if I push the amp into clipping.
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the guy has class, so its best to respect that.

as for this thread, has anyone emailed or talked to anyone at epifani directly?
 
#133
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.
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nice to see someone else actually reading the fine print. ;)
 
#134
Dr. Riddim said:
So everyone who has a non-Epi amp should definitely NOT consider buying an Epi cabinet. Anyone who already has an Epi UL-410 Series II and is powering it with a non-Epi amp should contact me immediately and sell it to me for pennies on the dollar so as to avoid the horrible consequences of blown drivers.:ninja:
Click to expand...

On a silly side note, your avatar reminds me of Amy Winehouse during her Grammy performance. :D
 
#136
Dr. Riddim said:
Anyone who already has an Epi UL-410 Series II and is powering it with a non-Epi amp should contact me immediately and sell it to me for pennies on the dollar so as to avoid the horrible consequences of blown drivers.:ninja:
Click to expand...

Not so fast, Doctor. Those of us who are smart Epi owners are going to wait until this whole thing blows over. Then our beloved Epi cabs will return to their original resale values. :eyebrow::D

M. M.
 
#140
To clarify the JBL papers, there are 2 different types of failures, the "low power" paper discusses the effects of clipping a full range signal on the tweeter component, but the paper I posted discusses the effect of clipping on the low frequency driver, in this paper primarily thermal failure. This paper is quite old, before the REALLY big amps were available, so mechanical damage was not very common.

What's important to understand is that you can solve the failure of a tweeter due to clipping by increasing the available power, but you then run the risk of damaging the low frequency driver due to excessive power. As with most things in life, there are limits to all solutions. ;)
 

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