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Thread: Will cane grill cloth block highs?

  1. #1
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    Will cane grill cloth block highs?

    I made new grills for my L100 and 4311 refurbishing project. Then I had a thought. What if this fairly heavy grill cloth blocks the highs from coming out of the dome tweeter?

    www.dcchomes.com/JBL.html

    This type of grill cloth is used on all of the Klipsch Heritage line, but those all have the K-77 horn tweeter. Is there a difference with a dome tweeter? Should I only be using the more transparent plain grill cloth?

    Thanks in advance for any help.

    Greg

  2. #2
    Administrator Mr. Widget's Avatar
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    First to answer your question. Yes it will adversely affect the HF response of your speakers. The sound waves coming from a tweeter do not know what type of device created them and will all be affected by the grille material in the same manor regardless of tweeter type. The more sheer the material the better. When critically listening I always remove the grilles. There is no grille material that is truly sonically transparent.

    Beyond that your question piqued my interest. The other day there was an article in AudioXpress describing what was entailed in replacing the T35A (K-77) that was standard in the Klipschorn and other Klipsch speakers for decades. Here is an anechoic plot of the T35A from EV that was featured in that article. I knew the little buggers were bad... but good grief this is terrible.

    Widget

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  3. #3
    Administrator Mr. Widget's Avatar
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    This is a plot of one of my L100s. It was taken on the woofer's axis with the speaker in the middle of the room raised about 1m from the floor. The response was better than I expected. The grille was removed and you will see a much better HF response than that little T35A can produce. The controls were both placed at the "Laboratory Standard" position... it did indeed produce the most linear response. I found measuring the speaker on the tweeter's axis the response was more uneven as there are significant cancellations between the mid and tweeter due to the overlapping nature of the design of the crossover.

    Don't mind the lack of bass. If you use the L100 in a small room or near room boundaries the bass increases significantly.

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    Senior Seņor boputnam's Avatar
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    Quote Originally Posted by Mr. Widget
    The response was better than I expected.
    Me too! All this time I thought it was the waterbed I liked...

    Well, it's 22C here in Johannesburg, and I'm going poolside with some fine Chardonnay. No-one's got a stereo here worth a dam - all teeny bullshit with crappy response but innocuous asthetics. Went to a disco last night - rager. Babes were dressed to the nines, and dancing amongst themselves. Wasteful, that... These babes are amongst the worlds most amazing eye candy - trust me. Anyway, the system was some near look-alikes to L100's - three-way coners, although with 15-in LF's, no horns, no subs. DJ was good, but after two-hours of the same throbbing un-changing and never-ending beat, I was done.
    bo

    "Indeed, not!!"

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    Quote Originally Posted by Mr. Widget
    This is a plot of one of my L100s. It was taken on the woofer's axis with the speaker in the middle of the room raised about 1m from the floor. The response was better than I expected.
    Yet another reason to listen with your hears instead of your microphone.

    In any case, nice graph!

    When are you going to drag your gear over to Bo's house and have a plotting party? There should be a whole plethora of neato systems to measure over there!

  6. #6
    Maron Horonzakz
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    Widget....The graph of the EV T35 is mine made many many years ago, At the Instatute for the Deaf. In St Louis. It was tested in a anechoic chamber. Along with many other drivers that day. John Warren borrowed the graph for his article. Can you imagine what it would look like with grill cloth in front of that tweeter?

  7. #7
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Greg Roberts
    Should I only be using the more transparent plain grill cloth?
    You can somewhat assess the acoustic transparency of your grille material by holding it up to the light and comparing its net free (open) area to standard grilles. Also, if the obscuration by the "canes" is 1/8" or more, I'd anticipate problems.

    It's easy to do a test: Run just the tweeters (on crossover, of course,) and from your listening position, have someone place and remove your grille material from in front of one of them. Your problem, if any, will be readily apparent.

    [Hmmmm. No subs or waterbeds in South Africa? Gonna make a note of that....]

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    I wonder if anyone has a graph showing the level of modulation distortion of the L100 with 75 watts input?


    Greg

  9. #9
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Greg Roberts
    I wonder if anyone has a graph showing the level of modulation distortion of the L100 with 75 watts input?


    Greg

    Sounds like Paul is still with us.

    Here are second and third harmonic distortion plots raised 20dB with input power at 5 watts. It was plenty loud.

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    Widget - do you know the "percentage" translation for distortion from -dB? For instance, if 3rd harmonic distortion is -40 db, do you know what percentage distortion that translates to? (I used to know the relationship, but it's buried away somewhere in my gray cells right now...)

    John

  11. #11
    Administrator Mr. Widget's Avatar
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    No. I'd have to research that, myself. Maybe someone has it at their finger tips.

    Widget

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    Well, I just did a quick interpretation from the 2012H spec sheet where they have both graphs and percentages listed for distortion, and it looks like 1% equates to about -35 dB and 3% equates to about -45 dB, at least as far as 2nd harmonic goes. 'Anyone know the technical conversion factors/procedure?

    John

  13. #13
    Senior Member grumpy's Avatar
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    If we're comparing power levels, (watts, not volts) I believe it goes 10log(ratio):

    -10dB = 10%
    -20dB = 1%
    -30dB = .1%
    -40dB = .01%
    ...

    or 3dB per x2 difference.

    I don't know the definition for THD (assuming it's summed non-fundamental
    power within some bandwidth). Of course I could be full of superbowl leftovers...

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    Quote Originally Posted by grumpy
    Of course I could be full of superbowl leftovers...

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    Quote Originally Posted by grumpy
    If we're comparing power levels, (watts, not volts) I believe it goes 10log(ratio):

    -10dB = 10%
    -20dB = 1%
    -30dB = .1%
    -40dB = .01%
    ...

    or 3dB per x2 difference.
    I'm aware of the power ratios you stated, and I think I've got a book or some documentation somewhere that goes over harmonic distortion, but I'll have to dig them out...

    Also, I believe that every doubling in distance from the speaker results in -6 dB, correct?

    John

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