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Thread: 275nd / S3100 compatibility

  1. #1
    Senior Member Bernard Wolf's Avatar
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    275nd / S3100 compatibility

    Hi everyone - I have searched the forum but still do not have my question answered. I am wondering if a 275nd would be a drop in replacement for the 2426H thats in the S/3100 now. Of course I know it will fit , as the 3100 mkII uses the nd, but my real question is will the crossover need to be changed as well. On one of the posts I read someone mentions that the sensitivity might be higher on the 275nd and thus require a crossover change. Can anyone confirm this ?

    Also, I do wonder if it would all be worth the effort. Will the nd sound that much better? The reason I ask all of this is that there is one 275nd up for sale at the moment and I am tempted to purchase it and wait for another.

    Any input would be much appreciated.

    Bernard

  2. #2
    pelly3s
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    there really is only one way to find out if it will sound better and that is to do it

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    Quote Originally Posted by Bernard Wolf
    Any input would be much appreciated.
    Okay, you've asked for some input :

    - I'd say, buy the 275nd and just drop it in ( if the price is right ) .
    - I also think that you should build some new "DC-Biased" crossovers, utilyzing better parts than those which presently exist in your stock crossovers . Make them external .

    - I have searched the forum but still do not have my question answered. I am wondering if a 275nd would be a drop in replacement for the 2426H thats in the S/3100 now.
    - I'm not surprised you can't find anything definative here. My recollection is that no one here, has ever done this "one for one" swap .

    Of course I know it will fit , as the 3100 mkII uses the nd, but my real question is will the crossover need to be changed as well.(?)
    - I don't think anyone here can tell you that based on my above point .
    - But, I would always assume that a crossover should be tweaked for a different component type.
    ie; Logically, why buy another driver type , if it's not actually different sounding ?

    On one of the posts I read someone mentions that the sensitivity might be higher on the 275nd and thus require a crossover change. Can anyone confirm this ?
    - I can't confirm any sensitivity differences, but swapping out resistors for more appropriate values is simple enough .

    Also, I do wonder if it would all be worth the effort. Will the nd sound that much better?
    - I've wondered about that myself. I hold more stock in the fact that I can readily hear the differences between the various types of metals used for the domes . But I find that any audible difference caused by the magnet type is much harder/ if not impossible to pin down ( at least with compression drivers ) . I've heard a response difference in le14 woofers, seemingly caused by the magnets ( Alnico vs Ceramic ) / though I tend to think the differences I've experencied were more likely caused by partially discharged alnico magnets .

    - If it was me ( & if I couldn't stand the suspense ), I would buy a pair of 275 replacement diaphragms ( plastic coated Titanium ) and install them into the stock 2426 drivers .

    FWIW - I think a more interesting upgrade path would be to retrofit a pair of 1.5" exit ( 243x ) drivers onto those big ( 1" entry ) horns . Zilch has mentioned an existing JBL adapter ( I think ) .

    ps ; Now that Zilch has a pair of similar 2346 horns ( along with the mentioned 3" diaphragmed drivers ) / help for this DIY modification just might appear along with some RTA measurements .



  4. #4
    RIP 2011 Zilch's Avatar
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    Yup, and some H2600's are on the way.

    2346's are a "trip." Just discovered last night that phase relationships wander all over the place unless the woofer is properly aligned with that long neck.

    I'm dubious about down-adapting 1.5" to 1", but I'll try it....

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    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Lancer
    1.5-inchers...

    Use a 1" exit cd with a titanium diaphragm that has a coating of aquaplas.
    That'd be 275ND replacement diaphragm in like 2425/6, no?

    Others?

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    Quote Originally Posted by Zilch
    Yup, and some H2600's are on the way.
    - I thought I previously read that N2600(s) are on the way. Anyway ,,,
    - You obtained H2600(s) ? Okay , who are you blackmailing ?
    - Well, if you get a pair of H2600 horns, it would sure be nice to get a close looky-see at the metal throat adapters. I think the metal throat splits into two parts .

    2346's are a "trip." Just discovered last night that phase relationships wander all over the place unless the woofer is properly aligned with that long neck.
    - Properly Aligned ? What does it physically work out to be ?

    I'm dubious about down-adapting 1.5" to 1", but I'll try it....
    - Yeh, these adaptions/contraptions are always dubious / still the exercise will give one an idea of the LF loading capabilties of a horn/driver combo .


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    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Earl K
    - Properly Aligned? What does it physically work out to be?
    What I know at this point is if you just stack 'em 2346's facing front on woofers (as in S3100) and get the two drivers in phase perpendicular, when you move the 30° onto real horn axis, you've got a big notch at 3110A 800 Hz crossover frequency. Inverting the HF driver phase makes it flat again, but screws it up perpendicular.

    "WAIT! You just DID that, silly!"

    Everest rotated the LF driver that 30° to put both drivers on parallel axes. I gotta free up some space here to work with different physical alignments to see what's up. Presumably H2600 will exhibit the same behavior. In any case, real time-alignment would appear to be, well, "challenging."

    Regarding the 275ND crossover, clearly S3100 and S3100 MKII use different topologies, the latter using what I'm calling the "parametric" approach of cascaded notches. I'll have to model them both to see if the newer (12/00) MKII is really different, or merely "improved" over the earlier (11/95) 2426H version. That'll also answer the question of "drop-in" interchangeability of the two drivers. Both networks are 750 Hz, 12 dB/octave, looks like....

    Quote Originally Posted by Earl K
    If you get a pair of H2600 horns, it would sure be nice to get a close looky-see at the metal throat adapters. I think the metal throat splits into two parts .?
    We'll see. Comes with, apparently:

    319381-001 HORN S2600/S3100 (+useTHROAT 318793-001)

    May afford opportunity to make a custom 1.5" throat for 243x drivers....

  8. #8
    Senior Member Bernard Wolf's Avatar
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    man .. ... you guys leave me in the dust so fast isn't not even funny

    will take me a day and a half to figure all of this out.... but thanks for the extra quick response.... should have put a stopwatch on it

    Bernard

  9. #9
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by Bernard Wolf
    [It]will take me a day and a half to figure all of this out....
    In short ... thus far, we don't know.

    But we encourage you to try it and tell us....

    Check me, now:

    A) S3100 has a deep notch at 2.5 kHz, whereas,
    B) MKII has, ummm, "undulations."
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  10. #10
    RIP 2011 Zilch's Avatar
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    Unless that's the 7.5-Ohm 1mH inductor, in which case, it's:
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  11. #11
    RIP 2011 Zilch's Avatar
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    That'sa familiar curve, actually.

    O.K., who's got an S3100 MKII we can tear into to get the DCR's of the inductors?

    [Kinda doubt the network's gonna show up on eBay....]

  12. #12
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    Unless that's the 7.5-Ohm 1mH inductor, in which case, it's:
    - That 7 to 8 ohm range looks right for that LCR filters' inductor.



    ps : Say Zilch , do you have an impedance plot for the le85 ? or is it buried in the Q&D 4430 thread ?

  13. #13
    Senior Member Bernard Wolf's Avatar
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    correct me if I am wrong, but is the 2426 not also aquaplas coated ? I can't find the service sheet that I once had for this, but if in fact the 2426 is coated then what is the big deal with the nd ? As Earl was saying, hearing the differences in magnet material may be a futile experience. As much as I would like to facilitate your wishes that I go ahead and try it and then report.. well, I am not quite that adventurous, or wealthy ..

    Bernard

    BTW, that 275 nd is up for auction on ebay right now.

  14. #14
    RIP 2011 Zilch's Avatar
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    LE85 Impedance plot, no horn.

    Call it 10 Ohms.

    Fmin is 1214 Hz.

    Dunno why I keep getting negative Le's on compression drivers here....

    I'd do it for you on S2600 horn, but that it comes without throat adapter.

    [Whatta buttlick!]

    Time out while I raise holy HELL with them....
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  15. #15
    Senior Member Lancer's Avatar
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    S3100 has a deep notch at 2.5 kHz

    Unless that's the 7.5-Ohm 1mH inductor, in which case, it's:

    You guys are getting it! Yes, don't leave out the DCR values for the coils.

    - That 7 to 8 ohm range looks right for that LCR filters' inductor.

    It's hard to say. You'd need a response curve of the driver/horn combo and then figure the DCR of the coil accordingly. I know some of the 1.0 mH coils were 6.8 ohms instead of 7.5 ohms.

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