Turning normal speakers into SDA’s

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Comments

  • delkaldelkal Posts: 729
    mlistens03 wrote: »
    delkal wrote: »
    mlistens03 wrote: »
    I wanted to get some 1 or 2 ohm resistors to wire in series with the speakers, and I still will most likely, but all they had at HobbyTown was ceramic resistors in those resistances, and I don’t know how that’ll work out with how much heat they produce.
    Thanks again!

    It shouldn't matter what the resistor is made of but you need to look at the wattage rating. I used two 1 amp 10 Watt resistors (one on each speaker). Anything with a higher watt rating is even better (but bigger and more expensive). Don't buy a little 1/4 watt resistor and think you are good. If its low ohm it will burn out instantly.

    There is a lot of science and formulas to tell you exactly what wattage is required for a resistor but there is a hack way for a reality check. If the resistor is exposed (like I described in my setup) just make sure it stays cool and doesn't get hot (I did say this was total hack!). Polk uses some 5 amp resistors in their monitor crossovers so I figured I was good with a 1 amp 10 watt resistor (and it was what I had in my parts bin). They stayed cool during my testing so I am thinking they will be OK (but i will keep checking every now and then for now)

    OK, I’ll buy some next time I’m over there.

    So, I made a mistake. I accidentally bought 1/8th watt resistors. :z I’m assuming I’ll probably blow these up if I get anywhere near 1 watt, right? That was the only wattage they had 1k and 10k resistors in, however I did get 1 watt resistors, although they are 100 ohms and 1k ohms. Will they work? I was under the impression that all that matters is that it is a 10:1 ratio.
    I don’t have my second Y-connector, I apparently let my friend borrow it, but I’ll get that tomorrow night.

    You are talking about 2 separate setups and need different resistors for both. For the way I set it up you need a 1ohm 10 watt resistor on each speaker. This is not the same as Kens suggestion that uses the line out voltage divider. His setup can use a lower watt resistor (not sure how low) because they are higher ohm. You need to use the ones he suggested. And its not just a 10:1 ratio. Its a 10:1 ratio with the correct high total ohms and the proper watt resistor.

    I would just take Kens advice and just spend $40 for the line level device he suggested. You will end up spending half of that in parts, figure out how to put it together with a circuit board, and hope you get it right. This way you know it will work.
  • mlistens03mlistens03 Posts: 2,759
    delkal wrote: »
    mlistens03 wrote: »
    delkal wrote: »
    mlistens03 wrote: »
    I wanted to get some 1 or 2 ohm resistors to wire in series with the speakers, and I still will most likely, but all they had at HobbyTown was ceramic resistors in those resistances, and I don’t know how that’ll work out with how much heat they produce.
    Thanks again!

    It shouldn't matter what the resistor is made of but you need to look at the wattage rating. I used two 1 amp 10 Watt resistors (one on each speaker). Anything with a higher watt rating is even better (but bigger and more expensive). Don't buy a little 1/4 watt resistor and think you are good. If its low ohm it will burn out instantly.

    There is a lot of science and formulas to tell you exactly what wattage is required for a resistor but there is a hack way for a reality check. If the resistor is exposed (like I described in my setup) just make sure it stays cool and doesn't get hot (I did say this was total hack!). Polk uses some 5 amp resistors in their monitor crossovers so I figured I was good with a 1 amp 10 watt resistor (and it was what I had in my parts bin). They stayed cool during my testing so I am thinking they will be OK (but i will keep checking every now and then for now)

    OK, I’ll buy some next time I’m over there.

    So, I made a mistake. I accidentally bought 1/8th watt resistors. :z I’m assuming I’ll probably blow these up if I get anywhere near 1 watt, right? That was the only wattage they had 1k and 10k resistors in, however I did get 1 watt resistors, although they are 100 ohms and 1k ohms. Will they work? I was under the impression that all that matters is that it is a 10:1 ratio.
    I don’t have my second Y-connector, I apparently let my friend borrow it, but I’ll get that tomorrow night.

    You are talking about 2 separate setups and need different resistors for both. For the way I set it up you need a 1ohm 10 watt resistor on each speaker. This is not the same as Kens suggestion that uses the line out voltage divider. His setup can use a lower watt resistor (not sure how low) because they are higher ohm. You need to use the ones he suggested. And its not just a 10:1 ratio. Its a 10:1 ratio with the correct high total ohms and the proper watt resistor.

    I would just take Kens advice and just spend $40 for the line level device he suggested. You will end up spending half of that in parts, figure out how to put it together with a circuit board, and hope you get it right. This way you know it will work.

    Sorry, I knew I was talking about two different circuits, next time I’ll remember to make the switch clear.
    Ok, so I’ll use the 1k and 10k resistors as a test. I found some breadboards (I think that’s what they are called) and I’ve been assembling it on that. I’ve got almost everything done, I just need to attach some form of connection for the speaker cables and swap out the resistors. I’ll test it briefly with the 1/8th watt resistors, then find (or order) some 1 watt versions.
    I know that the line level device would work better, but I don’t have $40 to put into an experiment if I don’t know that it’s permanent, and I don’t think my dad will let me accept the one as a gift from Ken.
    Thanks for the suggestions!
  • mlistens03mlistens03 Posts: 2,759
    Polkies are always helping each other out, I have the Russound and would happily loan it to you. Just PM me your address, then you can send it back when you're done if that is preferable to your dad.

    STRANGER DANGER!!

    Exactly what my dad thinks. Usually I would ask, but last time he seemed very on edge about it, I’m really worried he’d ask me to leave the forum altogether. And IMO, the Russound isn’t worth that, I don’t think anything I’ve been offered is worth that.
  • FestYboyFestYboy Posts: 3,858
    It better be a white van....
  • delkaldelkal Posts: 729
    I thought it was this white van. Gets me every time...........

    https://en.wikipedia.org/wiki/White_van_speaker_scam
  • ClipdatClipdat Posts: 9,025
    Very cool post Stan, thank you so much for sharing. :)
  • mlistens03mlistens03 Posts: 2,759
    skrol wrote: »
    I love this thread. This is exactly what got me into Polk Audio. Back in the mid to late 80's, I was in high school and starting college (EE), I was into audio, building my own speakers and playing around with multi-speaker setups and phasing to cancel crosstalk. I had some success but never achieved what I was listening for. At some point, I found a magazine article about Polk Audio's SDA speakers and was disappointed that someone beat me to it but thought it was pretty cool. Then I noticed that they were in my hometown of Baltimore and was hooked. My first manufactured speakers was a set of Pioneer ProMusica 120's but had my eye on Monitor 7's, then 10's. In 1991 I bought my first set of Polks, RTA-11TL and still have them today. About that time I saw an ad for an engineer at Polk Audio. Having just gotten my EE degree, I applied but didn't get the job. I knew it was a long shot. Funny thing is that I've never owned a set of SDA's and only had the pleasure of listening to a set of SDA 1.2TL's once at a shop in College Park.

    Many years later, at my church, I met a friend who used to design for Polk Audio and actually designed my RTA-11TL's. He claims to have a set of his own "Signature" SDAx.xTL prototypes tucked away. I'm hoping I can convince Zvonko to pull them out for a listening session some day. He left Polk in the early 90's. It is funny to think that I may have applied for his job.

    I hope you achieve the desired SDA soundstage. The advanced drivers and cabinetry of the LSi combined with SDA could be really cool. You have the advantage of seeing what Polk did previously with phasing and even adding additional speakers to the array.

    Stan

    Very cool. Thanks for sharing.
    I thought I had a fairly original idea with this... seems like I was very wrong. :)
  • HermitismHermitism Posts: 3,377
    mlistens03 wrote: »
    I thought I had a fairly original idea with this... seems like I was very wrong. :)
    Don't feel bad. I thought I had invented bi-wire speaker cables before joining here. I came up with the idea of running two pairs of speaker wire to each speaker, doubling the wire gauge. I thought I would be applauded for my ingenuity. Then I join here and I find out bi-wire cables already exist. I didn't even get to name my invention. I would have probably called it Double-Wire or TTW (twice the wire). Then once I joined here I kept getting bi-wire and bi-amping mixed up. I thought they meant the same thing.
  • Even though Ken is cracking jokes (and funny ones I might add) I get where your Dad is coming from dude. The internet is an odd place, can find good friends or enemies can find you without you having any idea you left traces.

    You can always do what we try in times of new gear "you don't remember I bought that a while ago but didn't need it until now"...he won't be none the wiser. >:)
    Just a dude doing dude-ly things

    "Temptation is the manifestation of desire which equals necessity." - Mikey081057
    " I have always had a champange taste with a beer budget" - Rick88
    "Just because the thread is getting views don't mean much .. I like a good train wreck doesn't mean i want to be in one..." - pitdogg2
    "Those that don't know, don't know that they don't know." - heiney9
    "Audiophiles are the male equivalent of cat ladies." - Audiokarma Member
  • mhardy6647mhardy6647 Posts: 26,567
    Not quite on topic, but I have this reprobate urge to share this golden
    oldie
    memory in this thread -- courtesy of the (in)famous Mr. Drew A. Kaplan ("DAK").

    pv7s31hdjhec.png


  • mlistens03mlistens03 Posts: 2,759
    Might've pulled this off once or twice... >:)
    However, it's hard to hide the 30+ pound package that comes to your door... not with the Russound, but with other stuff...:wink:
    I get where he is coming from as well. I think it would be very good to exercise caution on say, AK, and even here, but I am a lot more trusting here than I would be at AK.
    I think he'll realize that Y'all just wanna help at the Miami expo next year... I assume I'll be seeing at least some of you guys there, right?
  • mlistens03 wrote: »
    I thought I had a fairly original idea with this... seems like I was very wrong. :)

    Audio magazine published an article titled "Build A Passive Image Enhancer" in their November 1986 issue. Attached below is a PDF scan of the article and photo scans of the article pages.

    egpxcy4b9933.jpg

    dzac51vzkxgo.jpg

    e86yx8oz8bqc.jpg

    During Polkfest 2008, Matthew Polk demonstrated an SDA system consisting of four LSi9 loudspeakers with timing control provided by a Rane digital signal processor. Matthew mentioned that he and a Polk engineer had worked on the DSP algorithms for several months, and that they still had work to do.

    eb3dke8i89vp.jpg
    Figure 1. Right side LSi9s and Rane digital signal processor in Matthew Polk's home theater system.

    2ekzhkre38rs.jpg
    Figure 2. Matthew Polk sitting between the SDA-configuration LSi9s in his home theater system.

    Something like this would be of interest to an SDA enthusiast who found a conventional speaker with sound quality that he/she preferred over the SDAs, but didn't want to give up the panoramic sound stage of SDAs.
    "So hot it burns Mice!"~DK
    "Polk SDA-SRSs are hopelessly out of date both sonically and technologically... I see no value whatsoever in older SDA speakers."~Audio Asylum Member
    "Knowledge, without understanding, is a path to failure."~DK
    "Those who irrationally rail against something or someone that is no threat to them, actually desire (or desire to be like) the thing or person they are railing against."~DK
  • Thanks.

    I extracted the full color "Passive Image Enhancer" article from the magazine link.

    "So hot it burns Mice!"~DK
    "Polk SDA-SRSs are hopelessly out of date both sonically and technologically... I see no value whatsoever in older SDA speakers."~Audio Asylum Member
    "Knowledge, without understanding, is a path to failure."~DK
    "Those who irrationally rail against something or someone that is no threat to them, actually desire (or desire to be like) the thing or person they are railing against."~DK
  • VR3VR3 Posts: 24,021
    The people I've met on this forum have pretty much shaped my entire life. No exaggeration.

    Bad people exist in this world but only maybe 1% are into high end audio.... Ymmv
    - Not Tom

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • skrolskrol Posts: 2,916
    That's it! I used to have a subscription to "Audio" and that article got me started playing with speaker arrays and phasing. I remember the guy with the clarinet behind the sofa.

    Really cool about Mathew Polk and the LSi9 SDA too.
    Stan

    Main 2ch:
    Polk LSi15 (DB840 upgrade), Parasound: P/LD-1100, HCA-1000A; Denon: DVD-2910, DRM-800A; Monster HTS3600-MKII, Grado SR-225i; Technics SL-J2, Parasound PPH-100.

    HT:
    Marantz SR7010, Polk: RTA11TL (RDO198-1, XO and Damping Upgrades), S4, CS250, PSW10 (DXi104 upgrade), Marantz UD5005, Pioneer PL-530, Panasonic TC-P42S60

    Other stuff:
    Denon: DRA-835R, AVR-888, DCD-660, DRM-700A, DRR-780; Polk: S8, Monitor 5A, 5B, TSi100, RM7; Pioneer: CT-6R; Onkyo CP-1046F; Ortofon OM5E, Marantz: PM5004, CD5004, CDR-615; Parasound C/PT-600, HCA-800ii, Sony CDP-650ESD, Technics SA 5070, B&W DM601
  • I think the LSI9s are great speakers! I would totally invest in LSI9 SDAs!!
    2ch rig:
    Speakers: LSi9s with VR3's Fortress mods
    Preamplifier: Parasound P5
    Amplifier: Parasound A23
    CDP: Denon 1520
    Cables: Wireworld Equinox 7 XLR ICs, Wireworld Ultraviolet 7 USB
    Benched: Vincent SP-331
  • mlistens03mlistens03 Posts: 2,759
    DSkip wrote: »
    Or tell him to give me a call. While I wasn't as young as Trey, I did join this forum as a teenager and credit so much of who I am to this forum and the knowledge and friendships I've gained.

    I'm not sure I ever said this publicly, but the arrangement the forum sent to my wife's memorial service brought tears to my eyes then and still does when I think about it. My closest friends are here and a few aren't exactly within driving range.
    VR3 wrote: »
    The people I've met on this forum have pretty much shaped my entire life. No exaggeration.

    Bad people exist in this world but only maybe 1% are into high end audio.... Ymmv

    Skip, I’ll ask my dad about giving you a call tomorrow.
    Just out of interest, how old were you guys when you joined?
    I didn’t realize that there were others here who joined when they were about my age, until 2 weeks ago I figured out who “Sid the Kid” was. :)
    DK, thanks for the very interesting article!
  • Only 2 words. Cable management. mle6tarj4b49.jpg
  • ClipdatClipdat Posts: 9,025
    mlistens03 wrote: »
    I think he'll realize that Y'all just wanna help at the Tampa expo next year... I assume I'll be seeing at least some of you guys there, right?

    Fixed!
  • krazypolk wrote: »
    Only 2 words. Cable management.

    This was during the "work in progress" stage.

    "So hot it burns Mice!"~DK
    "Polk SDA-SRSs are hopelessly out of date both sonically and technologically... I see no value whatsoever in older SDA speakers."~Audio Asylum Member
    "Knowledge, without understanding, is a path to failure."~DK
    "Those who irrationally rail against something or someone that is no threat to them, actually desire (or desire to be like) the thing or person they are railing against."~DK
  • VR3VR3 Posts: 24,021
    Hmm, I joined in 2003... 13 or 14?

    Attended my first Polk fest at Polk hq at 15 or so?
    - Not Tom

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • VR3VR3 Posts: 24,021
    edited September 2018
    krazypolk wrote: »
    Only 2 words. Cable management. mle6tarj4b49.jpg

    Cable management only matters if you can see the wires, note the doors. If you look closer, that gear is positioned for access and practicality versus aesthetic
    - Not Tom

    "No, that's silly talk. Dude, you can't possibly be this audio dumb so quit the act." - Doro
  • mlistens03mlistens03 Posts: 2,759
    Clipdat wrote: »
    mlistens03 wrote: »
    I think he'll realize that Y'all just wanna help at the Tampa expo next year... I assume I'll be seeing at least some of you guys there, right?

    Fixed!

    That too. :mrgreen:
    Also... when did you learn to use the quotes correctly?
    :lol: sorry couldn’t resist.
    VR3 wrote: »
    Hmm, I joined in 2003... 13 or 14?

    Attended my first Polk fest at Polk hq at 15 or so?

    Ok, so you were my age at your first PolkFest. Cool.
    I wonder if my parents would let me go to PolkFest... where is it located usually anyways?
  • mhardy6647mhardy6647 Posts: 26,567
    edited September 2018
    skrol wrote: »
    That's it! I used to have a subscription to "Audio" and that article got me started playing with speaker arrays and phasing. I remember the guy with the clarinet behind the sofa.

    Really cool about Mathew Polk and the LSi9 SDA too.

    In case you didn't know it (and in case you might be interested), virtually every Audio issue ever published (as well as those of its predecssor, Audio Engineering) is available (PDF) thanks to https://www.americanradiohistory.com/Audio-Magazine.htm

    Audio, IMO, was the best of the lot in terms of consumer-oriented hifi periodicals.

    They also have expanding collections of scans of Stereo Review and High Fidelity -- as well as tonnes of other stuff.
  • scubalabscubalab Posts: 2,971
    Micah - I admire and salute your ambition with this experiment! My daughter is your age... I can't imagine her ever being this inquisitive about re-engineering something! I guess her interests are elsewhere and just don't quite align with this hobby.

    Kudos also to Ken S. for all the tips and support he's given you and not being a naysayer. I think it's very cool that you are 'experimenting' and hope you hit on something that sounds amazing to you!

    Regarding the Polkfests... to my knowledge, they have somewhat fizzled out in recent years, but in their heyday, I believe they were held at or near Polk's HQ in the Baltimore area. More recently, I think forum members still try to keep the tradition alive by hosting get-togethers at their homes. One of these days, I hope to get to one.

    Some of the best advice I've gotten has come from the great folks on this forum. However, I agree wholeheartedly with your dad with the 'you can't be too cautious' stance when it comes to the internet. I'd recommend sharing your hobby with him, letting him see how passionate you are about the hobby and the interest you have in (and the advice you've gotten from) the forum. I'm sure he'd be proud of how maturely you've presented yourself here, and your enthusiasm with the science and engineering in audio.

    Best of luck with this effort!!
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