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  • Wolf
    replied
    Wow, both of those were not as I was saying. Here's an altered graphic of my off the cuff:

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    Usually C1, L1, and R1 are in the main shunt leg of an SXO.

    Later,
    Wolf

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  • ericanderson
    replied
    Ok Wolf, thanks. Like I said it seems it will cost me more to make these drivers work. This is your off the cuffClick image for larger version

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  • Chris Roemer
    replied
    Here's my best interp. of Wolf's ideas.
    I added a 0.15mH coil inline w/the tweeter to flatten out the top end.
    This series XO uses
    3 coils: 1.0mH, and two 0.15mH
    4 caps: 8.6uF, 7uF (or 6.8), 5uF (or 4.7), and a tiny 0.68uF as a "tank" (around 6-7kHz)
    1 resistor (for tweeter attenuation): 10ohms

    Crosses near 2.7kHz.

    (sorry for the caveman art)

    Click image for larger version

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  • Wolf
    replied
    i was, but like I said- that was all off the cuff stuff. You want a model?
    Wolf

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  • ericanderson
    replied
    Wolf, are you going back to the series xo? I was just trying to use what I had and use as few parts as possible. I was looking at the Dayton 4 thread and just threw textbook values in. Seems like it would be cheaper to buy Dayton part's than try to whip these into submission

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  • Chris Roemer
    replied
    I PM'd you (so not to assist a hijack).

    Leave a comment:


  • cambe
    replied
    Hello,
    Sorry to jump in like this but, I am having trouble posting on my own. I need help with a crossover for a Peerless 832873 and Vita D26NC-55 combo.
    Regards,
    Cambe

    Leave a comment:


  • Wolf
    replied
    I would think L1 should be closer to 0.15mH, and C2 should be no bigger than 6.8; just to get your xover higher. However, the network does not include the 1.0-1.5mH coil for BSC between C1 and the woofer. I'd also place a 4.7uF or so in parallel with the woofer to rolloff the breakup, as well as a 0.1uF in parallel to the BSC coil.

    This is all off the cuff speculation, but should be closer. Increase R1 as needed, likely to at least 8 ohms in this case.

    I might model this for you later, if you are game...
    Wolf

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  • ericanderson
    replied
    Thanks again Chris not doubting you I
    ​​​​don't have test equipment so I guess I was questioning mfg specs again thank you for your time and help. Happy New year.

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  • Chris Roemer
    replied
    SBA 4" SB12PFC25-4 (fresh off site - soon to be NLA)
    Their "spec" says 87.5dB @ 2.83v
    WinISD calcs it as 86dB@1w(2v) ALMOST, and >89dB@2.83v - so... something seems hosed here, somewhere.
    (I've seen this kind of problem when mfrs. change data from dB/w to dB/2.8v and back. For XO work, we ALWAYS want 2.83v @ 1m. (3dB diff.)

    I traced their site's FR plot (supposedly @ 2.8v) which hovers at and below 85dB in the pass band, and wanders down to around 81dB above it.
    Full BSC is about -6dB, so you end up near 79dB.
    To me the tweeter looks to run around 89dB.

    If you've got a plot showing the woofer's FR closer to 88dB (or if you want me to just add +3dB to MY data, I can do that and), I can re-sim. This is NOT the 1st time I've seen this kind of SPL discrepancy.

    Leave a comment:


  • ericanderson
    replied
    Chris, are you looking at the sb13 5" or the sb12 4"? Graphs look like 87db for the woofer and around 89 for the tweet. 9-10db loss? Really wow🤔

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  • Chris Roemer
    replied
    Fc still around 1.5k.

    How about:
    HP - 10uF series cap, 0.20mH shunt coil, L-pad: SR=4n / PR=3n(ohms)
    LP - a 0.70mH series coil (w/a 4n resistor in series w/a tiny 0.33uF cap in parallel w/the coil as a "notch"), then an 8uF shunt cap (to gnd).

    Runs 78-79dB w/nearly full BSC. Fc @ 2.8k.

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  • ericanderson
    replied
    Chris, Thanks for the response. It's the 4n woofer. No it doesn't have to be series but it saves me from buying the big inductor. So parallel xo.1.5mh,15uf to ground lowpass. 3n before the cap 5.6uf, .20mh to ground highpass. Look better?
    Thanks again

    Leave a comment:


  • Chris Roemer
    replied
    You didn't specify the 4n(ohm) or 8n woofer.
    In either case, the 9-10k cone breakup remains quite high (only -5 to -11dB below the tweeter - as reference).
    The Fc is around 1400 Hz.
    Do you NEED this to be a series XO?

    Leave a comment:


  • ericanderson
    replied
    Ok, let me be more specific about what I am asking. Yes I know that it will work but will it be enough protection for the tweeter? Should be around 3k. I don't know how to use pcd hell I can't even get spl trace tr work so I never went any further... I understand the principals and I have these drivers on hand

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