Unoffical empeg BBS

Quick Links: Empeg FAQ | RioCar.Org | Hijack | BigDisk Builder | jEmplode | emphatic
Repairs: Repairs

Topic Options
#134060 - 09/01/2003 20:37 Eq distortion??blown tweeter
newguy1
enthusiast

Registered: 26/01/2002
Posts: 278
Loc: Massachusetts,USA
I was adjusting the eq frequency in the low end range (less than 60hz)when the frequency got down to around 20hz.At that point a loud screeching was heard from my right side speakers.Now it appears that the tweeter doesnt work. I think its toast.The volume was not very loud.Does this make any sense ?Any known issues with this situation?I did a search for equaliser on the FAQ but didnt find anything related. Should I post this somewhere else?


Edited by newguy1 (09/01/2003 20:40)
_________________________
MIKE 80Gb RIO

Top
#134061 - 09/01/2003 21:58 Re: Eq distortion??blown tweeter [Re: newguy1]
tfabris
carpal tunnel

Registered: 20/12/1999
Posts: 31597
Loc: Seattle, WA
There's a thread deep in bug reports somewhere, from a long time ago, where we were able to reproduce strange distortion by feeding the EQ some extreme values in fixed-q mode. As far as we know, it's some kind of a bug, either in the DSP itself or in the values sent to the DSP.

This is assuming you're running Beta 13. If you're running beta 11, there were even more serious bugs in the fixed-q mode of the equalizer.

Reason it's not in the FAQ: I try to avoid posting bugs in the FAQ, that's what searches in the bug reports forum are for. I make a few exceptions to that rule when it's a really widespread bug, but no one else reported this one because they didn't input extreme values into the EQ.

However, I never made it screech, and I could fix the distortion just by backing off on the extreme EQ values. Your screeching thing sounds more likely to be a problem with the amplifier going bad (though I can't say for sure). It's possible that it's not related to the EQ at all, or maybe only indirectly related. For instance, if you were adjusting the bass to be louder, maybe the amp tried to drive too much wattage into the speakers and fried a channel.

_________________________
Tony Fabris

Top
#134062 - 10/01/2003 13:52 Re: Eq distortion??blown tweeter [Re: tfabris]
tanstaafl.
carpal tunnel

Registered: 08/07/1999
Posts: 5549
Loc: Ajijic, Mexico
It's possible that it's not related to the EQ at all,

It would all depend on what sort of crossover network you have installed. A crossover network limits the frequencies sent to a given speaker. Your tweeter should have had a crossover setting that would have prevented any frequencies lower than about 5,000 Hz getting to it*. Thus, any equalizer adjustments you were making in the lower frequencies would have had no effect on the tweeter.

If, however, you are not running any sort of crossover network (the crossovers could be active within the amplifier itself; or more likely passive crossovers wired in-line with the speakers, probably provided by the speaker manufacturer) then all bets are off. You can and most likely will let the smoke out of your tweeters the first time you crank the volume up to any (un)reasonable level.

tanstaafl.

* This is not strictly true -- the crossover will have something like a 12 decibel per octave dropoff. That means that if you had the crossover set nominally at 5,000 Hz, you would have 2500 Hz frequencies getting through it at 12 dB less volume; and 1250 Hz at 24dB less; and so on.

db
_________________________
"There Ain't No Such Thing As A Free Lunch"

Top
#134063 - 11/01/2003 09:29 Re: Eq distortion??blown tweeter [Re: tanstaafl.]
newguy1
enthusiast

Registered: 26/01/2002
Posts: 278
Loc: Massachusetts,USA
Hi, yes i am running beta 13.the tweeters(MB Quart) are protected by a passive X-over around 3500hz.Also am running hi-jack 291 using the time delay feature.I was attempting to give a little boost 4db in the low range to get more effect out of my subs.I then shifted the frequency from 60hz down to the lowest setting (not sure exactly what it was)when the screeching sound was heard and noticed no output from right tweeter.I believe the Q value was fixed as i was only adjusting the frequency,so maybe thats the bug Tony was thinking about Switched tweeters to verify it was not working.Just listening to regular music (no test tones). I guess the thing to do is dont attempt that again!!
Now i have to decide to just replace that tweeter or spend some money and get a new set of components.Any recommendations for some MB Quart comparable speakers?
Mike
_________________________
MIKE 80Gb RIO

Top
#134064 - 11/01/2003 09:43 Re: Eq distortion??blown tweeter [Re: newguy1]
qbasic309
member

Registered: 23/10/2002
Posts: 110
I got my component sets from www.thezeb.com

They are Nakamichi's and sound great. Not sure what their price is like on them now but they carry good stuff at great prices.


Top