Frankenstein center out of 2 RT55i's driver sets + one tweeter

dkmuch
dkmuch Posts: 79
edited July 2009 in DIY, Mods & Tweaks
How difficult would it be to make an 8 ohm speaker out of two rt55i's, using only one tweeter and all four drivers?

Never mind the cabinet details yet unless the wiring is doable for a novice.

attachment.php?attachmentid=41564&d=1247072556
RT55i mains, CS400i center, FX300i surrounds, RTi15 rears, Energy S10.3 Sub, Onkyo 607 / PS3
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  • Tony M
    Tony M Posts: 11,159
    edited July 2009
    I liiiiike it!!!!!!!Good luck with the research. awsome idea.;)
    Most people just listen to music and watch movies. I EXPERIENCE them.
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  • kawizx9r
    kawizx9r Posts: 5,150
    edited July 2009
    Hmm, reminds us of the CS350 no? Cept it uses 4x4 1/2" drivers. I should be getting mine in soon and if you want I can take a look at the wiring in it for ya.
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  • nguyendot
    nguyendot Posts: 3,594
    edited July 2009
    Add a 50w amp to the two outside drivers and you got a CS1000p, no?
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  • kawizx9r
    kawizx9r Posts: 5,150
    edited July 2009
    What I was thinking, cept the drivers slightly differed for the subs no? Some cabinet modifications as well to internally seal off the mid-ranged drivers from the subs, thatd be a whole different world though :D
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  • dkmuch
    dkmuch Posts: 79
    edited July 2009
    Definitely don't need the bass, I've got a sub for that. I'm just worried my Onkyo 607 can't handle it if I wire it wrong (creating 4ohm or worse).
    RT55i mains, CS400i center, FX300i surrounds, RTi15 rears, Energy S10.3 Sub, Onkyo 607 / PS3
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  • kawizx9r
    kawizx9r Posts: 5,150
    edited July 2009
    Im sure others will chime in on how to wire in series/parallel to create an 8ohm load from your avr, as for the "bass", over 60% of audio in HT is played from your center channel. Having a center that can substantially reproduce some nice bass will sound so much better/fuller when watching movies that have explosions, cars crashing, guns firing/etc.
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  • dkmuch
    dkmuch Posts: 79
    edited July 2009
    If you guys think the wiring is doable @ 8ohm, I'll ask my carpenter friend about making a cabinet and matching grill ($$) to see if I can move forward on this and end my quest for a cs400i.
    RT55i mains, CS400i center, FX300i surrounds, RTi15 rears, Energy S10.3 Sub, Onkyo 607 / PS3
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  • kawizx9r
    kawizx9r Posts: 5,150
    edited July 2009
    Actually, vmaxer should have one if I remember correctly. He PMed me a bit late about it because I too was looking for one for awhile, but then I landed on some sda's and a cs350, so I didn't purchase his cs400i. Id say PM him
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  • dkmuch
    dkmuch Posts: 79
    edited July 2009
    You guys are talking about the CS1000p! I forgot all about that monster. Yeah, I could make a CS1000i, that's the ticket!

    The other part of the equation is, I might have spare RT55i parts and not need to spend on a CS400i.
    RT55i mains, CS400i center, FX300i surrounds, RTi15 rears, Energy S10.3 Sub, Onkyo 607 / PS3
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  • jcaut
    jcaut Posts: 1,849
    edited July 2009
    RT55 drivers are 4 Ohm and there's no way to wire four 4 Ohm drivers and wind up at 8 Ohms. It's 16 or 4. Bad idea acoustically, anyway, unless you do a 2.5-way with the outer woofers producing only bass. A better center could be made with one of the woofers and a tweeter, but even that would take some crossover design skills.
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  • kawizx9r
    kawizx9r Posts: 5,150
    edited July 2009
    out of the 4 mid bass drivers....hed only use 2 of them along with the tweeter if he went for the "cs1000p/i" idea. the outer 2 would be powered individually and wouldn't be directly wired for load with the other drivers and would run off a plate amp or the sort, DIY :D
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  • kawizx9r
    kawizx9r Posts: 5,150
    edited July 2009
    dkmuch wrote: »
    You guys are talking about the CS1000p! I forgot all about that monster. Yeah, I could make a CS1000i, that's the ticket!

    The other part of the equation is, I might have spare RT55i parts and not need to spend on a CS400i.

    If you do end up having spare parts (which may be the tri-laminate tweeter) let me know cause i'd be interested in it.
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  • messiah
    messiah Posts: 1,790
    edited July 2009
    jcaut wrote: »
    RT55 drivers are 4 Ohm and there's no way to wire four 4 Ohm drivers and wind up at 8 Ohms. It's 16 or 4. Bad idea acoustically, anyway, unless you do a 2.5-way with the outer woofers producing only bass. A better center could be made with one of the woofers and a tweeter, but even that would take some crossover design skills.

    Rt55's are rated at 8 ohms.
    "They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety."
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    messiah, November 23rd, 2010
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  • jcaut
    jcaut Posts: 1,849
    edited July 2009
    messiah wrote: »
    Rt55's are rated at 8 ohms.

    Yes, the two woofers are in series.
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  • dkmuch
    dkmuch Posts: 79
    edited July 2009
    Thanks for the responses. I ended up finding a CS400i, so now I have two tweeterless RT55i's with great cabinets and great drivers. Another pair of RT55i's with working tweeters and fairly decent cabinets (so much so, I'm not sure it's worth it to swap tweeters for a couple of dings).

    Kex could use the rt55i cabinets (his are damaged from his move), but I still feel they're worth repairing if I ever can get tweeters for less than $80. Kex doesn't need the drivers or XOers, just the cabs.

    I think I'll wait until a pair of RT35i's pop up for cheap and repair them.

    The other crazy idea I had was to use them as mid-bass modules / transducers in a 7.1+2 system -- aimed directly at the backs of our two couches (and hidden from view). The RT55i's can put out SPLs, when I run frequency sweeps on them, they'll almost knock you over. I'm kind of shocked by the power from "bookshelves"

    That's probably a dumb idea, as was my CS1000i.
    RT55i mains, CS400i center, FX300i surrounds, RTi15 rears, Energy S10.3 Sub, Onkyo 607 / PS3
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  • Airplay355
    Airplay355 Posts: 4,298
    edited July 2009
    Whats the big deal with making it 4 ohms? You're going to want an amp to power a speaker like that anyway so why worry about making a big speaker to run off an AVR?
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  • kawizx9r
    kawizx9r Posts: 5,150
    edited July 2009
    I still like the CS1000p/i idea. If I had a bigger living room and extra funds, I'd set out to look for one and move the CS350 to rear center duty :D
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  • kawizx9r
    kawizx9r Posts: 5,150
    edited July 2009
    Airplay355 wrote: »
    Whats the big deal with making it 4 ohms? You're going to want an amp to power a speaker like that anyway so why worry about making a big speaker to run off an AVR?

    Not all AVRs can run 4ohm speakers. From personal experience I've seen Onkyo's able to run 6ohm and above, and the Denon's I've owned can run 6 ohm and above as well.
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  • Airplay355
    Airplay355 Posts: 4,298
    edited July 2009
    I know not all AVR's can run an 4 ohm speaker but my point is that since he's building a speaker that large, regardless of it's resistance, it will be best suited for an amp, not an AVR. So since it should be used with an amp it's no big deal that he makes it 4 ohm because most amps (I can't think of one that can't) can handle a 4 ohm load.

    So, why worry about it? Just make it 4 ohm and use an amp.
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  • kawizx9r
    kawizx9r Posts: 5,150
    edited July 2009
    Lol it all came out to a huge misunderstanding. IMO this mod should be done the way the cs1000 was made, the 2 midrange drivers+tweeter utilizing an rt55/i crossover and run those speakers off an avr like normal (which will provide an 8ohm load), and the outer 2 midrange/bass drivers running off a plateamp to reproduce bass frequencies only. For the bass drivers though, that's where the DIY x-over will come into play.
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  • Airplay355
    Airplay355 Posts: 4,298
    edited July 2009
    Or instead of buying a plate amp, the components for a DIY xover and spending time/frustration building an xover he could go about building a big 4 ohm speaker and buy an amp to power the whole thing instead of just two drivers.

    Rt55i's -3db limit is 47hz, the -3db limit of the cs1000p is 45hz. Usually people cross their speakers over at 80 hz and send the rest to the sub so what's the point in having 2 dedicated woofers with their own plate amp and crossover in a center channel? You could cross the center at 80, 60, 50 and still be fine. Not to mention you don't gain much in frequency range by adding powered dedicated bass drivers.
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