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Thread: DBX DriveRack 4800

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    DBX DriveRack 4800

    I am currently using a Behringer DCX for my ScreenArray speakers in my home theater, and it does a very poor job in my opinion. Much hiss in my HF sections and not very refined sounding.

    I have found a DBX DriveRack 4800 under half the price of the MSRP and in perfect condition, so I am very tempted to buy it. I have read somewhere on this forum though, that DBX products are not very good and what goes in is NOT what comes out.. Is this true for the 4800 as well, or is it only for the cheaper models?

    Would the BSS London units be a better choice? (I know these are used in the Synthesis systems).

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    Senior Member Lee in Montreal's Avatar
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    Hi Jonas

    Your hiss problem is common with many other PA digital crossovers. While not state-of-the-art, the DCX remains a very good device. The hiss is related to the input/output gain and it can easily be solved. Here's a quick read:

    http://www.diyaudio.com/forums/digit...-over-280.html

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    Quote Originally Posted by Lee in Montreal View Post
    Hi Jonas

    Your hiss problem is common with many other PA digital crossovers. While not state-of-the-art, the DCX remains a very good device. The hiss is related to the input/output gain and it can easily be solved. Here's a quick read:

    http://www.diyaudio.com/forums/digit...-over-280.html
    Thanks for the response. Would you think the hiss would be the same with the DBX 4800? No matter what, I want to replace the DCX. I think its DA/AD convertes are way to harsh. I can clearly hear the change in sound when I put it into the chain even though all settings are set neutral.

    I'm very interested in what for example the BSS London Soundweb's can do, that the DBX 4800 cannot. As far as specs goes, they seem very similar. (I dont need all the input/outputs of the soundwebs though)

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    Senior Member Lee in Montreal's Avatar
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    Most household systems have a 1v sensitivity, while PA/pro systems need something near 3v. In both cases, the input at the crossover is the same. Therefore it exlains the much higher gain of a "professional" crossover. You may want to reduce the input level at each of the amps (at least by half), and turn that knob a bit more on your preamp. That should solve your problem.

    It would be great if manufacturers could include a switch on the back to select your output. 1v vs 3v.

    No experience with the DBX unit.

    BTW The DCX is not exempt of faults. My first unit had the dreaded frying egg floor noise and was replaced within 3 months. I suspect I was sold a refurbished unit. The second one I got works perfect. That problem is also very well documented and can easily be fixed.

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    Quote Originally Posted by Lee in Montreal View Post
    Most household systems have a 1v sensitivity, while PA/pro systems need something near 3v. In both cases, the input at the crossover is the same. Therefore it exlains the much higher gain of a "professional" crossover. You may want to reduce the input level at each of the amps (at least by half), and turn that knob a bit more on your preamp. That should solve your problem.

    It would be great if manufacturers could include a switch on the back to select your output. 1v vs 3v.

    No experience with the DBX unit.

    BTW The DCX is not exempt of faults. My first unit had the dreaded frying egg floor noise and was replaced within 3 months. I suspect I was sold a refurbished unit. The second one I got works perfect. That problem is also very well documented and can easily be fixed.
    I'm using a surround processor with XLR out.. they would think they shouuld provide enough input.

    I wouldnt be surprised if my DCX has a fault.. It is mostly one of the inputs (or one of the outputs) which has most hiss.

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    Senior Member Mctwins's Avatar
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    Hi
    Don't hesitate, if you can get it for half the prize, just buy it.

    The dbx4800 is better than the one you have. You have settings for the Cinema screen arrays and that goes for the dbx260 as well.

    I have myself the dbx260 and PA+ and have no hiss problem whatsoever. Very satisfied with both of them but dbx4800 is much better.

    Thanks

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    Quote Originally Posted by Mctwins View Post
    Hi
    Don't hesitate, if you can get it for half the prize, just buy it.

    The dbx4800 is better than the one you have. You have settings for the Cinema screen arrays and that goes for the dbx260 as well.

    I have myself the dbx260 and PA+ and have no hiss problem whatsoever. Very satisfied with both of them but dbx4800 is much better.

    Thanks
    I have already contacted the seller, and am awaiting reply. I think the dbx260 would be more than enought for my needs, but I would need two of them as I am using it for three front speakers in a home theater, and then the used dbx4800 is actually cheaper than two dbx260's. With the dbx4800, I can process all three LCR's and my two subs. Ideal situation for me.

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    Senior Member Mctwins's Avatar
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    Hi
    Perfect!!

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    So, I just picked up the DBX Driverack 4800... It had been used in a hifi-setup in a living room, so it was in absolutely perfect condition.

    I dont have the time to try it out at the moment, but in a weeks time, I will try it. I hope the improvement is noticeable

  10. #10
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    Quote Originally Posted by Jonas_h View Post
    So, I just picked up the DBX Driverack 4800... It had been used in a hifi-setup in a living room, so it was in absolutely perfect condition.

    I dont have the time to try it out at the moment, but in a weeks time, I will try it. I hope the improvement is noticeable
    Pictures please of current set-up and new set-up!



    I don’t get hiss now unless I turn the amp level up for the LCR HF and as long as I can hear pitches around near 16KHz on the rare occasion I’m not fussed. I think the cost is unbeatable for the DCX2496 its how you use it over high priced models that would cost 5 or more DCX2496!

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    Quote Originally Posted by JBL 4645 View Post
    I don’t get hiss now unless I turn the amp level up for the LCR HF and as long as I can hear pitches around near 16KHz on the rare occasion I’m not fussed. I think the cost is unbeatable for the DCX2496 its how you use it over high priced models that would cost 5 or more DCX2496!
    I know I can turn the gain down on the amp, but I dont like those "hack"-solutions... I'm not satisfied with the sound quality either. Have tried listening with and without the Behringer in the chain, and everything is much more transparent without it - more smooth and refined. I'm hoping the DBX will be unnoticable in the chain.

    EDIT:
    A picture of the system without the screen in front of it:


    The Behringer amps are all gonna be replaced with Crown CTs1200 for the LCR's and a Crown CTs2000 for the subs.. They are on their way.

  12. #12
    JBL 4645
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    Quote Originally Posted by Jonas_h View Post
    I know I can turn the gain down on the amp, but I dont like those "hack"-solutions... I'm not satisfied with the sound quality either. Have tried listening with and without the Behringer in the chain, and everything is much more transparent without it - more smooth and refined. I'm hoping the DBX will be unnoticable in the chain.

    EDIT:
    A picture of the system without the screen in front of it:


    The Behringer amps are all gonna be replaced with Crown CTs1200 for the LCR's and a Crown CTs2000 for the subs.. They are on their way.
    It’s no wonder you’re hearing hiss! I’ve seen that model before. I can’t see it on the JBL pro site unless its discontinued? I think the HF horns would have sensitivity of around 110db or less so its no wonder you’re hearing hiss. Turn the levels down! Those horns would blitz you’re ears in small room. My tiny little JBL control 5 tweeters can be rather bright hush if set at higher level in small room.

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    Quote Originally Posted by JBL 4645 View Post
    It’s no wonder you’re hearing hiss! I’ve seen that model before. I can’t see it on the JBL pro site unless its discontinued? I think the HF horns would have sensitivity of around 110db or less so its no wonder you’re hearing hiss. Turn the levels down! Those horns would blitz you’re ears in small room. My tiny little JBL control 5 tweeters can be rather bright hush if set at higher level in small room.
    Its a custom model.. Its the JBL 5641 enclosure with the 2226H driver (the LF section of the 3731) and the 4722-HF horn. They are 115db sensitivity I see no point of getting the 4722 with dual woofers in a home environment, therefore the "custom" model.

    My room is acoustically treated and the horns sound very smooth and pleasant. The amp gains are set the same for LF/HF but the HF has been lowered 18db on the DCX. (Well, lowered 15db and the LF raised 3db). So they are level matched (the LF is 97db sens.) The system sounds absolutely amazing to my ears! As you know, it is a lot like the gear in the Leicester - i visited that cinema about a year ago, and was very impressed with the sound.

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    Senior Member Eaulive's Avatar
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    Quote Originally Posted by Jonas_h View Post
    I know I can turn the gain down on the amp, but I dont like those "hack"-solutions... I'm not satisfied with the sound quality either. Have tried listening with and without the Behringer in the chain, and everything is much more transparent without it - more smooth and refined. I'm hoping the DBX will be unnoticable in the chain.
    To put the level down is not a hack, but instead a proper way to setup gain structure.
    99% of the hiss problems when using DSPs are related to an improper setup.

    There are many threads discussing "gain structure" here and on many sites.

    I suspect your DBX 4800, even if it's a very good unit and better than the Behringer, will also introduce hiss in your HF if the gain of your amplifier is all the way up.

  15. #15
    JBL 4645
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    Quote Originally Posted by Jonas_h View Post
    Its a custom model.. Its the JBL 5641 enclosure with the 2226H driver (the LF section of the 3731) and the 4722-HF horn. They are 115db sensitivity I see no point of getting the 4722 with dual woofers in a home environment, therefore the "custom" model.

    My room is acoustically treated and the horns sound very smooth and pleasant. The amp gains are set the same for LF/HF but the HF has been lowered 18db on the DCX. (Well, lowered 15db and the LF raised 3db). The system sounds absolutely amazing to my ears! As you know, it is a lot like the gear in the Leicester - i visited that cinema about a year ago, and was very impressed with the sound.
    I’ve been going to Empire for 21 years since it had the original JBL 13KW Lucasfilm THX sound system that was damn hard edge hitting for Dolby Stereo 70mm!

    Well which screen at Empire Leicester square because they have I think its 8 or 9 screens now, screen 1 is the big THX 56KW JBL screen! All the other screens use JBL I think the horns are the ones used for JBL 3678 I think some screens have duel 15” while ones not big enough to swing a cat around have single 15”.

    I think you’ve set the HF far too high for small room. Try setting the level over LCR HF at 75db while using wideband pink noise. Use an RTA and SPL db metre to make sure each have the same pressure and that each tonally sound the same some might have more output in different parts of the frequency response only an RTA can see that where the SPL db metre can’t see it unless its plugged into an RTA!

    Mute the HF LCR and look at the level on LF LCR and set the level at 75db. The subs should be within a few db they should merge smoothly.

    They look kinder funky I could fit a model like that in my living room but not enough space for 5 fronts. I like the HF horn that I could easily fit in the room. How you managed it the LCR are far too close to each other where in small digital screen at Empire the spacing between LCR would be a lot greater to insure widest possible stereo.

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