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Author Topic: Busted Speaker -- EQ Curve Looks GREAT! Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 04-09-2003 08:19 PM                     How is this possible? The HF section of two of these Altec speakers sound like crap. Dialogue is unintelligible and, yet, the EQ looked great on the RTA. This is a great example of the limitations of Pink Noise. You have to listen to a movie when it's all over. The dialogue sounded just like the pink noise! Wow!  |  IP: Logged Steve Kraus Film God Posts: 4094 From: Chicago, IL, USA Registered: May 2000 posted 04-09-2003 08:35 PM                    Yeah it would be neat if there was a good way to measure intelligibility and fidelity. Pink noise and an RTA is sort of like shining light through a piece of glass and measuring the throughput. It tells you what makes it through but not whether it's coherent; a precision lens vs. a glass brick.  |  IP: Logged Jonathan M. Crist Jedi Master Film Handler Posts: 531 From: Hershey, PA, USA Registered: Apr 2000 posted 04-09-2003 09:08 PM                     If you look at the end of each section of the Dolby manual it has the picture of an ear. It means that you are supposed to go out and listen to it when you are done with the eq. I have paid technicans a lot of money to eq my place and when they got done it sounded like crap (and the speakers were brand new). Why? because they are so married to their equipment they have forgotten how to listen. There is no better test equipment for how speakers sound than the human ear.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 04-09-2003 09:11 PM                     "I have paid technicans a lot of money to eq my place and when they got done it sounded like crap. Why? because they are so married to their equipment they have forgotten how to listen. There is no better test equipment than the human ear." ______________________________________________________________ I absoluteoy agree with that last line above. One MUST listen to his results before he can call it quits. ON the other hand one using cheap equipment should expect cheap results. A good analyzer will get you pretty darn close to where you should be with just minor corrections being necessary to complete things. With the R-2, I've actually had alot of tunning jobs end up sounding great, with no need to touch anything else. In these sorts of cases thuogh everything else was done correctly to begin with. Mark @ CLACO  |  IP: Logged Phil Hill I love my cootie bug Posts: 7595 From: Hollywood, CA USA Registered: Mar 2000 posted 04-09-2003 09:37 PM                  I ONLY agree with that line IF you are a professional and know what to listen for...NOT some rock & roller or rapper that has a distorted view/ear for good audio. AND remember, different speakers sound different to different people! If that wasn't true, ALL manufacturer's would use the same design and all sound the same! Audio reproduction and sound is a VERY personal and subjective thing when listening. >>> Phil  |  IP: Logged Rick Long Jedi Master Film Handler Posts: 759 From: Toronto, Ontario, Canada Registered: Nov 1999 posted 04-09-2003 09:50 PM                     I agree with Phil. The "audio quality judge" should be fully familiar with the original program material. Unless you personaly directed the print, how the hell do you know how it should sound? Fortunately we are equipped with test films such as the Jiffy and Listen prints from Dolby. Through near-daily use, the technician becomes more familiar with these than his own wife, used to every sound and nuance it can make (which, I suppose says a lot about my sex-life). Take away the variable of the recording, and you have a much better chance to properly evaluate the sound in your theatre.  |  IP: Logged Darryl Spicer Film God Posts: 3250 From: Lexington, KY, USA Registered: Dec 2000 posted 04-09-2003 11:24 PM                    ok here is a suggestion when setting up sound systems new or even readjusting. thread up a reel of known good quality trailers or run a 20 minute reel of film with every thing set to the center position on the EQ's (New installs only) after setting up the A-chains of course. Go in and listen to the sound. Take notes about your opinions of the sound. Is it muffled lackiung in bass or what ever. Now pull out the test gear hook everything up and calibrate your system to the required curve. Now listen to the same reel again. Compare what you hear to the notes you mad and notate anything that may sound strange. if no problems great if there are problems tweek where needed by running the reel again and doing minor tuning. To be honest every B chain should be checked with every different feature. But we must be honest in this day and age of tweeking every theater to every feature is not possable. So when checking the systems mix up the previews with ones that are quiet and ones that are action or do the same with the feature reel if possable. Get every thing to sound as good as you can on both levels of action and quiet to get the norm.  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 04-10-2003 01:55 PM                     Okay, but my question was: How is it possible to get a good-looking EQ out of a busted HF Driver ?  |  IP: Logged Michael Schaffer "Where is the Boardwalk Hotel?" Posts: 4143 From: Boston, MA Registered: Apr 2002 posted 04-10-2003 03:01 PM                        Did the EQ "look good" on the RTA but the levers on the equaliser were all over the place? Neoghbouring bands should not be equalised too far apart. That is one indication of a speaker problem.  |  IP: Logged Don Sneed Master Film Handler Posts: 451 From: Texas City, TX, USA Registered: Aug 2001 posted 04-10-2003 06:28 PM                        Not all techs are equal, some do things is different ways but we all get to the same results...after I do a EQ, I then run a 20-min. test reel I carry with me to check different things such as the surrounds kicking in when suppose to, check the surround delay, and front channel image, tone, & volume...if anything doesn't not sound right, then back to the EQ & do it again until right....I agree with Manny & Phil, we all (techs) rely on our test equipment (of course), but our ears are the best test equipment we have, but as we all age, our ears do lose the higher freq., example would be the 15K hz from our TV's, when we were younger we could heard this, faint but it could be heard...now at age 49 my hearing to limited to 12K, I cannot heard beyon 12K, & as I get older it will get lower...getting old sucks !!! so to recap, reply on the test equipment & ears..my feeling is to do it right or don't do it at all !!!  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 04-12-2003 09:51 AM                     If enough energy is applied then even the base section will reproduce the highs One also has to remember that if you see an unusual curve forming on the trim pot settings I start looking for the problem elswhere Also when you say the HF was busted in what respect was it busted open circuit ripped diaphram  |  IP: Logged Manny Knowles "What are these things and WHY are they BLUE???" Posts: 4247 From: Bloomington, IN, USA Registered: Feb 2002 posted 04-12-2003 05:57 PM                     I was getting sound out of that HF driver so would that automatically rule out an open circuit? I visually inspected the diaphragm and it is not ripped. I did, however, find a lot of little metal filings all over the outside of the magnet -- how do you get those off? My hunch at this point is that there may be some filings caught in the gap where the diaphragm goes. Does this sound like a possible cause to anyone?  |  IP: Logged Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 04-12-2003 06:43 PM                     You can use a loose stronger magnet to attract the particles. It is a good practice to clean the gap with a business card to dislodge any small filings that may fall into the gap when changing diaphrams....a diaphram may look good, especially flat wire types but may be distorted. If you can, when you pull out a diaphram, note the location of the old unit so when you check the coil of that unit, if you should find a rubbed or burned spot, you can check the gap for debris at that point. Richard Fowler Kinoton America Inc  |  IP: Logged Mark Seaton Film Handler Posts: 7 From: Glenview, IL, USA Registered: Aug 2002 posted 04-14-2003 12:11 PM                        Hi Manny, It is indeed possible to get sound out of a malfunctioning drive unit. Most commonly this can be the result of a scratching/rubbing voice coil as a result of non-catastrophic overheating, or hard physical bottoming of the former. The latter is more commonly seen with woofers, not compression drivers. The other possibility would be some foreign substance in the magnetic gap. If things are rubbing or scratching, sufficient drive level will indeed produce sound, and the time-averaging of an RTA might not clearly depict the problem. I would expect a moderate level frequency response measurement(not RTA) would likely show what you are hearing. I would first remove the diaphram and clean the gap with compressed air and maybe a business card as suggested by others for any metalic material to guaranty that is not the problem. The filings clinging to the outside of the magnet are of no concern on the outside, but if they get in the gap, that's a definite problem. Older Altec's had some serious magnets on them, so any metal would be quickly attracted. Regards,  |  IP: Logged

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