Wharfedale Emerald Center Channel Distortion

Discussion in 'Speakers' started by SeanA, Aug 10, 2003.

  1. SeanA

    SeanA Second Unit

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    I have just recently noticed that my Wharfedale Emerald center channel speaker is distorting when the sound peaks... kind of a rattling sound. I have all Wharfedale speakers in my surround system and the center channel speaker is the only one with this problem. Can it be that this speaker is already bad after only 18 months of use and only modest volume output (never above 1/2 of the receivers capacity), or could there be another culprit ?

    I rechecked all my connections and everything looks fine. I am not an expert on sound systems by any stretch, so I just want to rule out any other possibilities before I service or replace the Wharfedale speaker.
     
  2. Geoff L

    Geoff L Screenwriter

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    Hi Sean

    You mentioned a rattling type noise, this sounds more likely to be something loose rather than distortion.

    Check the Centers *rear port*, and the grill to see if the noise is coming from either. Remove the grill and listen while touching the port lightly. See if it is rattling or buzzing..
    If you can turn your other speakers off, it may make it easier to detect the problem.

    The grills are known to rattle and buzz at med to higher volumes.

    If you "have" or are running the center large,,,,, or even small but crossed over below 80Hz you could have possibly damaged a driver.
    If it has (always been run small and crossed at 80Hz or above), then very doubtful that one of them would be cooked/blown.

    Try those out first and see if you find the culprit. We have Oak Emeralds in the Bedroom and the 99-mains (grills) will buzz or rattle at high volumes.
    No problems with the "Emerald Oak Center", 95-surrounds, or 93-rears.

    Have other ideas but check those first.
    Regards
    Geoff
     
  3. SeanA

    SeanA Second Unit

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    Geoff,

    Thanks for the suggestions... I will give them a try. My use of "rattling" was probably a poor choice of words. It is more of a "buzzing" as you mentioned. I do hope it is something simple like the grill.

    You mention using the Center with the "large" setting as potentially damaging the driver. I do believe I have been running it with the "large" setting, but I thought that was the proper setting for most center channel speakers. How do I know if it should be "large" or "small" ???

    I will let you know what I find.
     
  4. Geoff L

    Geoff L Screenwriter

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    Sean

    The center speakers USABLE frequency response, dictates what it should be set at.

    Your center should NOT be run large. When set this way it is being feed a full range signal. The usable freq response of the Emerald is only good down to about 70Hz or so where it rolls off quickly. After this the speaker has no protection and if set large it trys to produce signals below the 70Hz safe area.
    At low or very low volumes one can get away with it, but if the volume goes up or way up, your looking to damage the drivers. The woofs generally would go before the tweeter in this situation, center set large=full range=bad idea.

    Set it small and selecting a crossover point of 80Hz or above would be the proper way to run this speaker.

    I don't know if you have a sub, but "generally" in this situation (speakers and powered sub), all speaks are set small and the low frequency information is sent to the sub from those speaker channels. The sub will also get the .1 information so nothing is lost.

    None of the speakers in the Emerald line are TRUE full range capable speaks. The 99's and 97's can be run large if one dose not have a sub, but I'd pay attention to how loud one pushes the volume in a no sub situation.

    Don't sweat it even if you have damaged the Center speaker, Wharfedale will replace the drivers free, even possibly send a whole new speaker.

    If the noise is not the port or grill, you can check the driver (not the tweeter), buy carefully placing your thumbs on the cone evenly on each side and half way down to the dust cap, then pushing in (softly and evenly). Do this with nothing playing obviously
    Your listening for a scratchy sound, no scratchy sound cool, scratchy not good. You have to push in on the driver ~{softly and evenly}~ so it goes straight in. If one side is pushed harder and un-even with the other, it will not go in straight and may scratch anyway.
    So be sure to do it evenly when checking both the drivers in the center speaker...

    It will not hurt the driver when done properly, even if you do it a little un-evenly one time, it will be ok.
    It's really a very simply and an easy test.
    But check the port and grill stuff first.

    If you've run the center large sence new you may have damaged the drivers and being that you listen at lower levels, it's just now finally had enough.

    Do you have a set up disc, Avia, VE, S&V, etc, and a SPL meter?

    Also are you running a sub?

    And what models Emeralds do you have along with your Receivers selectable crossover points when set small?

    Sorry for the long post, just trying to cover as many bases as possible and also get more information from you...

    Cheers
    Geoff
     
  5. SeanA

    SeanA Second Unit

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    Hey Geoff,

    Don't apologize for the long post... I really appreciate all the help.

    I just tried your thumb pressure test and I did not get any scratchy sound. And I did just recently run the AVIA speaker balance test. I found that my center channel had to be dialed back some. I also heard the disturbing "buzz" sound from the test signal when it came round to the center channel. This is what confirmed my suspicion that something wasn't quite right with the center speaker. I think I will try the Avia balance test again with the center set to SMALL and see if I get the distortion. I did remove the screen and checked the port in back, and neither seem to be the cause of the "buzz".

    My set-up is as follows:

    Aiwa AV-D98 Receiver
    Denon DVD 1600
    Front - Emerald 97's (Large)
    Center - Emerald (Large... but will be changing to Small)
    Surrounds - Diamond Anniversary (Large)
    No Sub (don't care for real deep bass)

    I set all these speakers to LARGE because I didn't have the Sub and because the Denon DVD 1600 manual suggests setting the speaker to LARGE if it can handle frequency output below 100 Hz. I actually just got the DVD 1600, but I think I had the LARGE setting for all my speakers when I was running with the Toshiba SD4800 player. And I did start noticing the problem with the Emerald center during the last couple weeks with the SD4800.

    You have really got me thinking now, and I hope you don't mind a few more questions:

    1) Should the Diamond Anniversary surrounds be set to SMALL as well ? They are rated down to 40 Hz, so I thought a LARGE setting would be appropriate.

    2) Do some receivers allow for the LARGE & SMALL settings ? My Aiwa does not seem to have this function, so I made the setting on the DVD player. I am not sure how I would set the crossover frequency. Again, it does not look like the Aiwa has settings for crossover. (Maybe I need a better receiver).

    3) Am I better off using the test signals on the Avia disc or the test signals directly from the receiver to set speaker balance ? I even have test signals on the Denon DVD 1600, but I would think it is best to keep the Denon at 0 dB for all speakers and adjust the level through the receiver.

    4) What do I do with the LFE on the Aiwa receiver ? Should I turn it off to prevent possible damage to the speakers or should I just adjust it down to a lower dB level ? It looks like I can turn it down to -20 dB, in 5 dB increments. 0 dB is the default for LFE.

    5) This may be unrelated, but when I put my ear next to the tweeter on each speaker, there is a very noticeable "hiss". If I move my ear about a foot away or more, the hiss becomes virtually unnoticeable. Is this normal ?

    Thanks again, Geoff. I will let you know if I discover anything interesting.
     
  6. Geoff L

    Geoff L Screenwriter

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    Sean

    Do you have the owners manual for your top of the line Aiwa receiver?

    You seem to be using the 5.1 analog outputs from the Denon 1600 plugged into the Aiwa receiver to decode DD and DTS.
    This is why the receiver won't let you do any bass management. Set up this way, "it has to be done by the DVD player".

    You should use the digital out on the DVD player and let the Awia receiver do the decoding. Then you can set your speakers up properly. The 1600 dose have bass management when using the 5.1 analog outputs to decode DD DTS, but has a fixed crossover at 100Hz and limited controls for bass management. Better than most DVD players, but you should let the RECEIVER do the decoding for DD and DTS and not the player.

    I am not talking about DVD-A, just DD DTS. They have a set of seperate outputs on the back of the Denon and would be need to be used when play DVD-A disc.

    I tried to find specs/information on your receiver and did eventually find a down loadable manual, but I am unable to access PDF files. I do know that your receiver dose DD DTS and definitely should have small settings for the different speakers and most likely selectable crossover points.

    Definitely read your Aiwa manual or download//print it off the Aiwa site.

    That Denon is a very nice player, but you have things hooked up a little wrong for DD DTS.

    If you watch the entire Avia disc, it explains pretty much everything you need to know for receiver, dvd player, and speaker set up..

    Regards
    Geoff
     
  7. SeanA

    SeanA Second Unit

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    Geoff,

    I will take another run through the Aiwa manual to see if I can find a section on speaker settings. However, I am not using the 5.1 connections but the optical output on the Denon. If I do find I can change speaker settings (I guess this is what's called "bass management") with my Aiwa receiver, how do I know which piece of equipment (DVD player or receiver) is dictating the bass management ? It doesn't seem to make sense that one would create speaker settings on both devices... am I correct ? If I am to let the receiver perform the bass management, do I change the base speaker setting on the Denon from my current "multi-channel" setting to "2-channel" ? The Denon manual states to select "multi-channel" when 3 or more speakers are connected, but to select "2-channel" when 2 speakers or an amplifier with a Dolby Pro Logic decoder is connected.

    I might as well ask for your opinion on the Aiwa receiver too. Would I notice a vast improvement in sound if I bought a quality Denon or Harmon Kardon receiver ? I have been thinking about it.

    Thanks for hanging with me.
     
  8. Geoff L

    Geoff L Screenwriter

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    Sean

    After reading all the reviews I could find on all Aiwa receivers, (over 135 of them), I think that you really would be best served by getting a new receiver, and BIG TIME!!!!!

    Anything from any of the main players would be better than what you have. I apologize as this dose sound a bit harsh...:b

    You are certainly not getting the performance that your other equipment is capable of with the Aiwa.
    I'm not even sure your receiver dose the typical 96 for DVD, it appears as tho all the Aiwa's I read about are plagued with allot of problems and (down mix digital DVD to 44)...!

    This totally unacceptable in a receiver, and even if yours dose do 96 and you have had no problems to this point with it, I still think you will be floored with the difference a better receiver will make.

    And I'm NOT talking getting some TOP of the line Marantz, Denon, etc. Any mid line preferably or even "upper entry level" receiver from an of the major companies, H/K, Denon, Yamaha, Onkyo, Nad, even Panisonic, Pioneer, etc would make a huge difference.

    I would seriously consider this and then unload that Aiwa...

    Regards
    Geoff
     
  9. SeanA

    SeanA Second Unit

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    I have been seriously considering putting a new receiver on my shopping list. I did no research whatsoever when I bought the Aiwa a couple years ago (before I really got interested in home theater), and I have slowly been realizing it is a weak point now in my home theater set-up. I really appreciate you doing all the homework I should have done from the start !!! Just one question though... what are you referring to with the numbers "44" and "96" ?

    I must mention though that I think I discovered the problem with my center channel, and fortunately I don't think anything is wrong with the speaker... but I feel like an idiot !!! I went back through the Aiwa manual and noticed that there is an impedence switch (4 ohm and 8 ohm) on the back. I checked it out and lo & behold, it was set to 4 ohms !!! I must have bumped the switch a few days ago when I was attempting to relocate my equipment in my entertainment center. It was right after this that I started noticing the distortion from the center channel speaker. Does it make sense that the wrong impedance from the receiver could cause such a problem ? (The sound seems much better now and so far I have not noticed any more buzzing). And is it possible I did any permanent damage with the wrong impedance over just a few days ?

    I did discover that the Aiwa has a "Normal" (small center channel) and "Wide" (large center channel) mode, but no control of crossover. I assume that the crossover is the low frequency level and below in which only the "large" speakers will operate... correct ? I was running in the "normal" mode, so my center channel should have been protected from too low bass.

    Lastly, I also discovered that I should set the Denon DVD 1600 to "2-channel" mode as opposed to "multi-channel" mode when watching DD or DTS encoded DVD's to let the receiver do the decoding. I think this is what you were telling me, and that the "multi-channel" mode on the Denon is mainly for DVD-Audio or if the receiver does not have a DD/DTS decoder.

    Thanks Geoff... I have more than doubled my limited home theater receiver knowledge in just the last couple days.
     

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