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  1. #1

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    Smile SDA-CRS Mono Modification Advice

    I have purchased a set of SDA-CRS's with 2 SL-2000 tweeters and 2 MW-6503 woofers in each speaker. I have already converted them to polyproplyene capacitors and mils resistors and eliminated the poly switches.
    and haved used them as center channels with and without without the interconnect

    I would like to convert to mono speakers to use as dual center channels. I ran across one post that said just connect the Dimensional ground to the the Stereo ground in each speaker and eliminate the cable. I have tried this using jumpers. Seems to sound better.

    I was wondering if anyone has done it a different way. I notice the the SDA
    and stereo tweeters are wired slightly differently. The woofers appear to have the same wiring scheme.

    The SDA-CRS schematic is posted on this forum thread for reference.

    My main front speakers are SDA-SRS's that use the same drivers.

    I use SDA Stereo for Music and surround sound with the center for movies and the center for TV

    Any advice would be appreciated. Thanks

    Bill

  2. #2

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    I ran a pair of CRS+'s for dual center channels for a while, then I replaced them with dual LSiC's, then replaced the LSiC's with dual LSi9's. I would still be using the dual CRS+'s if not for their bulk. I switched to smaller speakers strictly for aesthetic reasons. Of course, the dual CRS+'s were perfect timbre matches for the SDA SRS's I am using for front speakers in my HT.

    I rewired the CRS+'s dimensional drivers to be in parallel with the stereo drivers. This dropped the nominal impedance from 6 to 4 ohms, so if you do this, make sure your amp is comfortable with low impedances.

    Forum member Larry Chanin is using a pair of CRS+'s in his home theater, but I don't recall if he rewired the drivers. Here is a link to his home theater page:

    Larry Chanin's Home Theater
    "Polk SDA-SRSs are hopelessly out of date both sonically and technologically... I see no value whatsoever in older SDA speakers."~Audio Asylum Member
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  3. #3

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    Thanks for the input. I effectively have the drivers in parallel, with my jumper and have plenty of power. Driving with an modified XL-600

    The question I have have is the stereo tweeter has a 5.6 Ohm resisitor with a .5uf capacitor across it prior to the 12uf capacitor, wheras the dimensional tweeter just has a 7.0 ohm resisitor before the 12uf capacitor. Should I make them the same, and which should I use

  4. #4

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    Polk found that the dimensional tweeter wasn't needed for true stereo reproduction and in fact sometimes introduced unnatural artifacts, thus it was deleted from subsequent CRS versions. Since you will be running a mono signal, the dimensional tweeter is even more redundant and you could just disconnect it.

    You might also consider wiring the dimensional tweeter in parallel with the stereo tweeter, but I don't know if this would drop the impedance too low.
    "Polk SDA-SRSs are hopelessly out of date both sonically and technologically... I see no value whatsoever in older SDA speakers."~Audio Asylum Member
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  5. #5

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    Right now I have the woofers and both tweeters wired in parallel, however as I stated before, the two woofers have the same circuit componets. Where as the tweeters have
    a different resistor capacitor on the incoming signal

    I would like to make them the same but not sure which way i should go. What is the purpose of the .5uf capacitor across the 5.6 ohm resistor on the stereo tweeter. should I make the dimensional side the same?

    I have looked at several other SDA schematics some have .5uf cap and some don't

    Thanks,

    Bill

  6. #6

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    I modded some SDA's to drop the dimensional tweeter. As DK suggested disconnect the Dim tweeter, and also you can change the stereo resistor to 3.5 ohms seeing you are only using one tweeter. This will bring the stereo tweeter up to the volume level of the mid woofers. I would remove the .5uf cap.
    Ben
    Last edited by ben62670; 10-14-2008 at 12:08 PM.
    Please. Please contact me a ben62670 @ yahoo.com. Make sure to include who you are, and you are from Polk so I don't delete your email. Also I am now physically unable to work on any projects. If you need help let these guys know. There are many people who will help if you let them know where you are.
    Thanks
    Ben

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    Thanks, Ben

    So I will end up with two woofers and crossovers wired in parallel, and one tweeter with a 3.5 ohm input resistor, no capacitor bypass, and I will disconnect the other tweeter. Right.

    Thanks,

    Bill

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    You are talking per speaker correct?
    Please. Please contact me a ben62670 @ yahoo.com. Make sure to include who you are, and you are from Polk so I don't delete your email. Also I am now physically unable to work on any projects. If you need help let these guys know. There are many people who will help if you let them know where you are.
    Thanks
    Ben

  9. #9

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    yes, for each speaker one tweeter and two woofers

  10. #10

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    you got it:)
    Please. Please contact me a ben62670 @ yahoo.com. Make sure to include who you are, and you are from Polk so I don't delete your email. Also I am now physically unable to work on any projects. If you need help let these guys know. There are many people who will help if you let them know where you are.
    Thanks
    Ben

  11. #11

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    Default old CRS mono/center thread

    Quote Originally Posted by ben62670 View Post
    you got it:)
    Hi Ben,

    I saw your old thread about the use of crs as a center channel. I have the older 2 tweet/2 mid CRS. I am not too keen on opening and rewirig my speakers, if i wired the crs pair in parallel, will they be an effective center channel? without the sda interconnect only the inner tweet will function right?

    Ryan

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