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Thread: recommendations?

  1. #1
    Senior Member cjwebber's Avatar
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    recommendations?

    Hey guys-
    my current system includes:

    32ohm d140r
    16ohm 375
    16ohm 2403

    i had a crossover built by a gentleman in California.

    he said the crossover was designed at 800hz/7000hz with 12dB slopes, and was designed with the 32ohm woofer in mind.

    I admit, I do not have much technical knowledge - I simply love hifi and JBL.

    the weak point in my system is either 2 things...poor crossover design or the woofer choice. Or both.

    I say this, because I am hearing a major lack in low and low mid.



    Id really love to take the next step in upgrading my system. Really, I'm looking for suggestions on what to do next. New woofers and new crossover?

    something else???

    thanks guys!
    HOME: Dynaco ST-35 & C37 & C38
    WORK: Sequerra Met 7's

  2. #2
    Administrator Robh3606's Avatar
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    Why don't you begin by attenuating the 375 and 2403. That should help balance the system. You are not going to get much of anything below 40Hz so even balanced you may miss the last octave, that said you will have a very lively system.

    Rob
    "I could be arguing in my spare time"

  3. #3
    Senior Member cjwebber's Avatar
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    Thanks for your reply!

    i have attenuated the 375 and 2403 quite a bit. I'll do some more experimenting with that tonight.

    Let me clarify: the frequency range I feel that I'm missing is the lower end of vocals. I.e. Vocals are sounding a bit air-y.

    I'll take some photos of my speakers and crossover when I'm home tonight.
    HOME: Dynaco ST-35 & C37 & C38
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  4. #4
    Senior Member louped garouv's Avatar
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    Maybe you could borrow some subs, etc. to
    see if an addition of low frequency energy
    would help out with your set up?

  5. #5
    Administrator Robh3606's Avatar
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    Vocals are sounding a bit air-y.
    Have you tried a phase change between the 140 and the 375?? You mean the middle of the woofers range??

    Rob
    "I could be arguing in my spare time"

  6. #6
    Administrator Mr. Widget's Avatar
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    Assuming your drivers are all up to snuff you have an excellent collection of parts there... from your avatar, I am assuming you have a 2397 clone as your horn. It is a good horn, but it doesn't fully support the driver below about 1200Hz and so there is a roll off. This could be part of your issue.

    But as Rob suggested turning down the compression drivers and swapping driver phase may also help. Even starting with top flight drivers and horns, assembling a speaker that is truly outstanding isn't trivial. DIYers do it every day, but few are really well balanced and reaching the potential of the parts they use. That said, it is one hell of a fun journey and if you persist you will end up with a very fine system.


    Widget

  7. #7
    Senior Member cjwebber's Avatar
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    Quote Originally Posted by louped garouv View Post
    Maybe you could borrow some subs, etc. to
    see if an addition of low frequency energy
    would help out with your set up?
    I'll give that a shot. thanks!

    Quote Originally Posted by Robh3606 View Post
    Have you tried a phase change between the 140 and the 375?? You mean the middle of the woofers range??

    Rob
    By this, do you mean reversing the polarity on the 375? on the d140r? on both? thanks!

    Quote Originally Posted by Mr. Widget View Post
    Assuming your drivers are all up to snuff you have an excellent collection of parts there... from your avatar, I am assuming you have a 2397 clone as your horn. It is a good horn, but it doesn't fully support the driver below about 1200Hz and so there is a roll off. This could be part of your issue.

    But as Rob suggested turning down the compression drivers and swapping driver phase may also help. Even starting with top flight drivers and horns, assembling a speaker that is truly outstanding isn't trivial. DIYers do it every day, but few are really well balanced and reaching the potential of the parts they use. That said, it is one hell of a fun journey and if you persist you will end up with a very fine system.


    Widget
    I have switched to 400hz EdgarHorns. Thank you for the encouragement and wisdom!
    HOME: Dynaco ST-35 & C37 & C38
    WORK: Sequerra Met 7's

  8. #8
    Senior Member cjwebber's Avatar
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    Switching the polarity on the 375 made a world of difference! Thank you!


    This got me wondering:

    Is there a way to test each driver to find out which terminal is positive and which terminal is negative, so that I am positive everything is hooked up properly?
    HOME: Dynaco ST-35 & C37 & C38
    WORK: Sequerra Met 7's

  9. #9
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by cjwebber View Post
    Switching the polarity on the 375 made a world of difference! Thank you!


    This got me wondering:

    Is there a way to test each driver to find out which terminal is positive and which terminal is negative, so that I am positive everything is hooked up properly?
    It isn't that simple... swapping horns of different lengths may require phase reversal, or changing the crossover topology may require phase reversal. It isn't simply a matter of red and black.


    Widget

  10. #10
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    As Widget said, getting a DIY effort "right" isn't usually trivial. If you're determined to get the most from your speakers, I'd suggest learning how to measure the frequency response. Without knowing that, you can only guess whether the crossover, speaker polarity etc. is correct.
    Oppo BDP-95 DCX-2496 RMX-850 Parasound A21 First Watt J2 Dayton RSS390HF-4 MTM Quads of SEAS W18E001 511Bs TAD TD-2002

  11. #11
    Member sean19's Avatar
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    calibrated attenuators

    i also think you should attenuat the 375 and 2403 the only ones i found online that were calibrated to match the db's on the face plate so you know -6 is really six and -8 is really 8 and so forth are these off ebay $19.95 each free shipping PHILMORE LP100 MONO L PAD Contol & Plate 100 watts RMS 8 Ohms


  12. #12
    Senior Member 4343's Avatar
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    Quote Originally Posted by sean19 View Post
    i also think you should attenuat the 375 and 2403 the only ones i found online that were calibrated to match the db's on the face plate so you know -6 is really six and -8 is really 8 and so forth are these off ebay $19.95 each free shipping PHILMORE LP100 MONO L PAD Contol & Plate 100 watts RMS 8 Ohms

    It's not really that simple. The electrical attenuation may be close to the faceplate value, but driver sensitivity is also a factor. And where is the zero point? If, like most designs, you put a fixed-resistor-pad in front of the variable L-Pad, zero can be anywhere on the dial you'd like it to be.
    And those are 8 ohm pads, and the drivers in question are 16 ohmz...
    Mike Scott in SJ, CA
    Drive 'em to the Xmax!

  13. #13
    Senior Member ivica's Avatar
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    Try to MEASURE to be SURE

    Quote Originally Posted by fpitas View Post
    As Widget said, getting a DIY effort "right" isn't usually trivial. If you're determined to get the most from your speakers, I'd suggest learning how to measure the frequency response. Without knowing that, you can only guess whether the crossover, speaker polarity etc. is correct.
    I can agree with fpitas, as measurements would be (on my opinion) the first starting point, but at the end total "acoustic preferable character" has to be done listening a lot of different 'materials' doing a small amount of "L-pad" adjustments.

    regards
    ivica

  14. #14
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by ivica View Post
    I can agree with fpitas, as measurements would be (on my opinion) the first starting point, but at the end total "acoustic preferable character" has to be done listening a lot of different 'materials' doing a small amount of "L-pad" adjustments.

    regards
    ivica
    Yes, and I think this needs to be done over a period if time with breaks between listening sessions.


    Widget

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