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Thread: Polarity issues again

  1. #1
    Member Wilsonj's Avatar
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    Polarity issues again

    Here we go. I have gone threw most of the threads and I’m still confused. My receiver has A&B speaker engage buttons. If I put a set of L100A late (123A-3woofer) on A and a set of Nova L88 on B and engage booth buttons at the same time will I have polarity (oppositely phased drivers) issues? If you want to hang me for this I guess it’s only fitting that I supply the rope.



    Jim

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    This is Bos' territory,,, but ,

    Given the two models of speakers here's my suggestion ;

    (i) Hook up one of each type to the respective A & B outputs for just the right channel on your receiver . then

    (ii) Put both speakers into close proximity of a rooms corner ( close = mere inches away from the wall/corner & each other)

    (iii) Play bass heavy music first into one speaker & then both speakers ( attenuate as much as you can the top end & midrange content ) .

    (iv) What you're doing is a listening test. If the woofers are in phase the bass will get louder when you engage the "B" button. If the sound thins out when the two woofers are played together, then they are out of phase.

    (v) If the woofers are out of phase / I think I would simply flip the polarity of the cabling running to the L88s

    (vi) I wouldn't worry much about the phase/polarity on the tweeter sections unless the two box types are closestacked ontop of each other. If that's the case / maybe buy bigger speakers .




  3. #3
    Member Wilsonj's Avatar
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    Quote Originally Posted by Earl K
    This is Bos' territory,,, but ,

    Given the two models of speakers here's my suggestion ;

    (i) Hook up one of each type to the respective A & B outputs for just the right channel on your receiver . then

    (ii) Put both speakers into close proximity of a rooms corner ( close = mere inches away from the wall/corner & each other)

    (iii) Play bass heavy music first into one speaker & then both speakers ( attenuate as much as you can the top end & midrange content ) .

    (iv) What you're doing is a listening test. If the woofers are in phase the bass will get louder when you engage the "B" button. If the sound thins out when the two woofers are played together, then they are out of phase.

    (v) If the woofers are out of phase / I think I would simply flip the polarity of the cabling running to the L88s

    (vi) I wouldn't worry much about the phase/polarity on the tweeter sections unless the two box types are closestacked ontop of each other. If that's the case / maybe buy bigger speakers .




    Thanks Earl, makes sence. Now if I could only afford bigger speakers.

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    Senior Member Don Mascali's Avatar
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    The ol' D cell battery and a short piece of wire is a good trick. Look to see if the woofer moves in or out and hook them up acordinglly.

    Edit: I have used this for compression drivers out of the box too. You stretch a piece of plastic wrap over the exit and you can see if it moves in or out. I can't ever remember which driver does what, and this is a quick and dirty check.
    4406, 4412A, L100, L100t3 (3 pair), L1, L7, 4645C, 4660A, 4695B, SR4735 and various DIY JBL Pro loaded systems.

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    Hi Jim'

    - I'm trying to understand the genesis of your confusion & understand why you have these overall polarity concerns,,,, So , what's up ? What is it that you are trying to accomplish that concerns polarity is preventing ?

    ANOTHER TEST ( I see Don as jumped in ) good !
    - Another simple polarity test is the 1.5 volt battery type. Simply connect the batteries terminals to those of each speaker type ( of course they must be disconnected from amp first ) . The 1.5 volts DC is sufficient voltage to cause a visual cone displacement of the woofer. Find the battery orientation that moves the woofer cone outwards for one of your speaker models. Remember what battery connections go to which color terminal on the back of the speaker box . Repeat this exercise at the other type of speaker. Note the relative direction of cone movement in comparison to the first box. If they are both outwards then both woofer types in their own boxes are "in phase".

    - It's always good to test things twice and do two types of tests to corroborate the findings .

    - I've looked at the schematics for both speakers / and according to them the tweeters should be in phase if you don't revrese polarity of the speaker cables.

    EDIT : ( see Bos' post at the bottom - my assumption is apparently wrong )

    - So , forget what I said above about simply reversing cable polarity if one type of woofer is out of phase . If a woofer type is out of phase, flip one model type ( say the L88 ) inside the box by reversing the wires .

    EDIT : ( see Bos' post at the bottom - apparently a simple switch of the polarity of the cabling going to the L88 is the way to go )


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    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by Wilsonj
    Here we go. I have gone threw most of the threads and I’m still confused. My receiver has A&B speaker engage buttons. If I put a set of L100A late (123A-3woofer) on A and a set of Nova L88 on B and engage booth buttons at the same time will I have polarity (oppositely phased drivers) issues?
    Silly question... are you using them all in the same room? If so why? If not polarity and phase don't matter.

    Widget

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    EDIT :
    Jim - a AA battery is enough voltage to see sufficient cone movement for the phasing test ( I just did it ) . Don't use a 9 volt.



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    Administrator Mr. Widget's Avatar
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    I've always used a weak 1.5V D cell... works fine.

    Widget

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    Member Wilsonj's Avatar
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    Quote Originally Posted by Earl K
    Hi Jim'

    - I'm trying to understand the genesis of your confusion & understand why you have these overall polarity concerns,,,, So , what's up ? What is it that you are trying to accomplish that concerns polarity is preventing ?



    Here is the reason. I have a rather large receiver 250w per side. I own a pair of L100A late. And was looking at adding another pair of speakers to the system in the same room. I thought things would be fine with that much power But then I came accross the phase issue.

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    Hi Jim

    Okay,, I get it .

    Do you have enough info now to figure out the phase & polarity issues ?


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    "The ol' D cell battery and a short piece of wire is a good trick" I thought a D size cell (Battery) was 1.5 Volts. Where did the 9 Volts come in? If D cell means Dry Cell then it could be many different Voltages. Or is it that you guys are just "Funnin" and trying to catch the sleepers? As you can tell I'm new here, but none the less, I enjoy reading and learning about the "Alchemy" of sound.

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    "The ol' D cell battery and a short piece of wire is a good trick" I thought a D size cell (Battery) was 1.5 Volts. Where did the 9 Volts come in? If D cell means Dry Cell then it could be many different Voltages. Or is it that you guys are just "Funnin" and trying to catch the sleepers? As you can tell I'm new here, but none the less, I enjoy reading and learning about the "Alchemy" of sound.

    - No , the 9 volt reference was from my end. All from my own bad brain / not Dons' .

    - My apologies to Don for the inference and any implications made .

    rek50 - Glad to see you are not asleep ! ( obviously I am )


  13. #13
    Senior Member Don Mascali's Avatar
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    A "D" cell is the large 1.5V flashlight battery. As was noted I wouldn't hook it up and walk away, but a quick tap of the wire is enough to see which way the cone is going. The 9 volt was mentioned by some one else.

    I read about the "D" cell thing years ago in a David Weems book on building speakers. He showed a little rig with a double throw switch and a battery in a tuna can, to test polarity and woofer damping in a box. You switch it back and forth and listen for an equal thump, You add or remove stuffing to make them sound as close as you can for proper closed box damping. This does work if you don't have a signal generator or other test gear.

    All of my ideas are stolen from others.
    4406, 4412A, L100, L100t3 (3 pair), L1, L7, 4645C, 4660A, 4695B, SR4735 and various DIY JBL Pro loaded systems.

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    - I've edited my previous posts to remove the 9 volt references .

    - As just mentioned ,, it all started in my brain ( as an incorrect assumption on my part )

  15. #15
    Member Wilsonj's Avatar
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    Quote Originally Posted by Earl K
    Hi Jim

    Okay,, I get it .

    Do you have enough info now to figure out the phase & polarity issues ?

    yes and no. I would need both sets of speakers to do the test to see if they are in phase with each other. At this time I only have the L100A late. I did the test on them. Positive on the battery to red on the binding post and negative on the battery to black on the binding post the cone moved in. reversed settings and the cone moved out. If I got the same results with the L88s they would be in phase with each other. Right? It would be nice to know the results of this test on the L88 before I bought the L88s.

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