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Thread: S3900 S4700 dbx DriveRack 260

  1. #16
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    Is the internal crossover not bypassed? Isn't that missing a large point of going active?

  2. #17
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    Quote Originally Posted by bubbleboy76 View Post
    Is the internal crossover not bypassed? Isn't that missing a large point of going active?
    The purpose of the exercise was to add delay and to arrive at true LR 24 filters, then evaluate the results. It was not to go full active and bi-amp either system. No one is advocating that anyone who owns an S3900 or S4700 run out and buy a dbx and a second amp. It just so happens that the exercise resulted in very positive changes. I have no idea where it all fits into the total equation, e.g. does two grand for a dbx and a second amp yield a greater bang for the buck than hooking up a single two thousand dollar amp?
    Quote Originally Posted by Mctwins View Post
    Ok, the amp question has been answerd

    Still don't get it about the numbers of PEQ(10 total in S4700) How did G.T do this??

    Does he mix prePEQ and postPEQ together??
    I've never looked at the dbx manual. If one has to use pre and post to get ten then yes, that is what he did. No different than the Crown HD and M2. I have posted how the Crown HD and M2 were configured and they do indeed use pre and post. It has been mentioned that the problem with the dbx and the lesser Crowns is that there are not enough PEQ points to properly implement an in-room fully active setup.

  3. #18
    Senior Member grumpy's Avatar
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    Buy two... go digital out on the first and digital in on the second, clocking them together?
    (I'm just blowing smoke... can you even do that without cutting into their guts?)

  4. #19
    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by grumpy View Post
    Buy two... go digital out on the first and digital in on the second, clocking them together?
    (I'm just blowing smoke... can you even do that without cutting into their guts?)
    What is it that you're smoking?


    Widget

  5. #20
    Senior Member grumpy's Avatar
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    Good question... I was thinking 4800/20 apparently, with digital I/O.

  6. #21
    Senior Member pos's Avatar
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    So any follow-up on this project?
    What about the E2 ?

    The 4430 for example would clearly deserve some DSP magic...
    David Smith recently said something along those lines on the diyaudio forum, more specifically about the 2344 and how good it would become if properly EQed.

  7. #22
    Senior Member pos's Avatar
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    Found the post:
    http://www.diyaudio.com/forums/multi...ml#post3599353

    Quote Originally Posted by speaker dave (David Smith)
    If cheap DSP is a given then maybe the old 2344 was the perfect horn. It certainly had the most ideal polars and d.i. Axial response was an exact copy of the driver's power response. There were no bad angles response wise. The one issue was low end roughness that could easily be handled with a bit of DSP.

    Just sayin...

    David

  8. #23
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    Quote Originally Posted by pos View Post
    So any follow-up on this project?
    What about the E2 ?

    The 4430 for example would clearly deserve some DSP magic...
    David Smith recently said something along those lines on the diyaudio forum, more specifically about the 2344 and how good it would become if properly EQed.
    Quote Originally Posted by pos View Post
    The E2 arguably deserves the IT HD Crowns as opposed to the DBX.

    I've always thought the 2344's were great, never did find any Be diaphragms to bolt to them though.

  9. #24
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    Everest II and DSP

    Quote Originally Posted by pos View Post
    What about the E2 ?
    "I haven’t gotten back into working with the DBX or with any other speaker models. I am using an AllDSP model PLP226 Signature. It is basically 2 in and 6 out which works for my Tri-amp system I am not using the UHF at all. I actually did my design with my speakers in place in my living room. I put in a 4 th order LR crossover target (750 Theoretical) and made 4 mic measurements of each of my woofers and HF units. Averaged the 4 positions for each transducer and used those 6 curves as the transducer measurements. I then applied the necessary crossover slopes and frequencies to get the acoustic measurement to match the electrical target as closely as possible. It doesn’t matter what electronic slope and frequency is used so long as the actual acoustic response is close.

    Next I applied the necessary EQ to get the crossover slopes tuned in. Once done, I turned everything back on and made a Left (or Right) channel measurement using the same 4 mic positions averaged. The summing came out nearly perfect, as it should. I did the time delay by choosing one of the mic positions that gave the smoothest curve through crossover and inverting the polarity on the HF. I adjusted the delay for the deepest and most symmetrical notch at crossover. Flip the phase and all goes flat again. Finally, I applied some global EQ to the entire system to clean up any remaining room of summing issues. It is very simple to do, but it takes forever due to the multiple measurements and repetitive nature of things. My results were awesome.

    The DBX Driveline 260 can do the job nicely although it is a little limited in PEQ filters. You have to be pretty efficient. I am currently looking at other High End solutions which incorporate built-in Preamp functions so I can ditch my analog preamp. Among the contenders are the Ground Sound DCN28 and the DEQX HDP-4. All are pretty pricey. The DBX is cheap at about $1000."

  10. #25
    Senior Member ivica's Avatar
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    4 mic position

    "I haven’t gotten back into working with the DBX or with any other speaker models. I am using an AllDSP model PLP226 Signature. It is basically 2 in and 6 out which works for my Tri-amp system I am not using the UHF at all. I actually did my design with my speakers in place in my living room. I put in a 4 th order LR crossover target (750 Theoretical) and made 4 mic measurements of each of my woofers and HF units. Averaged the 4 positions for each transducer and used those 6 curves as the transducer measurements. I then applied the necessary crossover slopes and frequencies to get the acoustic measurement to match the electrical target as closely as possible. It doesn’t matter what electronic slope and frequency is used so long as the actual acoustic response is close.

    Next I applied the necessary EQ to get the crossover slopes tuned in. Once done, I turned everything back on and made a Left (or Right) channel measurement using the same 4 mic positions averaged. The summing came out nearly perfect, as it should. I did the time delay by choosing one of the mic positions that gave the smoothest curve through crossover and inverting the polarity on the HF. I adjusted the delay for the deepest and most symmetrical notch at crossover. Flip the phase and all goes flat again. Finally, I applied some global EQ to the entire system to clean up any remaining room of summing issues. It is very simple to do, but it takes forever due to the multiple measurements and repetitive nature of things. My results were awesome.

    The DBX Driveline 260 can do the job nicely although it is a little limited in PEQ filters. You have to be pretty efficient. I am currently looking at other High End solutions which incorporate built-in Preamp functions so I can ditch my analog preamp. Among the contenders are the Ground Sound DCN28 and the DEQX HDP-4. All are pretty pricey. The DBX is cheap at about $1000."


    Hi 4313B,

    Have You any idea what are the mic positions : '...made 4 mic measurements of each of my woofers and HF units..."

    Regards
    ivica

  11. #26
    Senior Member grumpy's Avatar
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    Hi Ivica,

    I am sure you still would prefer the answer from "the source", but I can recommend emulating the
    locations where a pair of people's ears would likely be while listening ... roughly a 3ft wide window.

    When setting up Titanium Dome's "250Ti" 4-way active system, -final- in-room measurement/adjustment
    cycles were accomplished this way. This seemed to pass muster with the visiting audio giants that this
    process was described to, followed by a bit of listening. Many other individual measurements were made,
    but this last step helped to correlate listening experience to worthwhile adjustments. E.g., balancing in-situ
    FR measurements between channels greatly enhanced imaging/sense of space.

    I'd be happy to hear specific recommendations (and rationale) as well.

  12. #27
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    Quote Originally Posted by Bobecca View Post
    I have to correct myself here. I really dont understand how it is implemented in dbx260 or how the connection is done. What does the INPUT stands for, is it prePEQ or postPEQ?? I asume it is the prePEQ that is used here.

    In the dbx260 it is not possible to have more than seven prePEQ(first and last is only shelving type of filter) and four postPEQ(on each output).

    How is it possible to have 10 parametric settings on that provided chart(S4700)?

    It can not be biwired in this config. It has to be two amps involved!

    Am I missing something???????
    There are 6 notch-filters that can be used as reducing PEQs as well in the DBX 260.
    So you have 7prepeq+2pre-shelf+6notch+4LF postpeq+4HFpostpeq+4UHFpostpeq to use.

  13. #28
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    Quote Originally Posted by 4313B View Post
    S4700 BiWired

    Courtesy of Greg Timbers.
    The delay-setting here, is it stated in time (ms)? Or distance?

    (this great thread needs to be bumped now and then)

  14. #29
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    Quote Originally Posted by 4313B View Post
    "I haven’t gotten back into working with the DBX or with any other speaker models. I am using an AllDSP model PLP226 Signature. It is basically 2 in and 6 out which works for my Tri-amp system I am not using the UHF at all. I actually did my design with my speakers in place in my living room. I put in a 4 th order LR crossover target (750 Theoretical) and made 4 mic measurements of each of my woofers and HF units. Averaged the 4 positions for each transducer and used those 6 curves as the transducer measurements. I then applied the necessary crossover slopes and frequencies to get the acoustic measurement to match the electrical target as closely as possible. It doesn’t matter what electronic slope and frequency is used so long as the actual acoustic response is close.

    Next I applied the necessary EQ to get the crossover slopes tuned in. Once done, I turned everything back on and made a Left (or Right) channel measurement using the same 4 mic positions averaged. The summing came out nearly perfect, as it should. I did the time delay by choosing one of the mic positions that gave the smoothest curve through crossover and inverting the polarity on the HF. I adjusted the delay for the deepest and most symmetrical notch at crossover. Flip the phase and all goes flat again. Finally, I applied some global EQ to the entire system to clean up any remaining room of summing issues. It is very simple to do, but it takes forever due to the multiple measurements and repetitive nature of things. My results were awesome.

    The DBX Driveline 260 can do the job nicely although it is a little limited in PEQ filters. You have to be pretty efficient. I am currently looking at other High End solutions which incorporate built-in Preamp functions so I can ditch my analog preamp. Among the contenders are the Ground Sound DCN28 and the DEQX HDP-4. All are pretty pricey. The DBX is cheap at about $1000."
    I think I will try this procedure on my newly procured 4429:s

    I would also like to know which 4 mic positions he used. On the floor, etc?

  15. #30
    Senior Member 1audiohack's Avatar
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    Sounds fun!

    Barry.
    If we knew what the hell we were doing, we wouldn't call it research would we.

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