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Thread: Stereo sub bass myth or reality?

  1. #1
    JBL 4645
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    Question Stereo sub bass myth or reality?

    Here’s a strange one and I kinder tinkered around with my DCX2496 you can read the rest of my dribble on the link below.

    Stereo Bass-Is it real and if so is it worthwhile?
    http://www.avsforum.com/avs-vb/showthread.php?p=15668293#post15668293

    Also the OP had this link that looked like it was brewing into flame war in 1.1 microseconds!

    Burn-in: Real Or Imagined???
    http://www.avsforum.com/avs-vb/showthread.php?t=874883&page=22

    Personally I feel it needs a lot of trail and error to make it work for the average Joe at home.

    It also seems costly but doesn’t mean it won’t work just needs a lot of trail and error.

    One idea about giving this some thought would be the fronts would it be wide or narrow deepening on room size?

    I think an array of JBL lined along the sides of the length of the room might give some perception of stereo sub bass to each seat and beyond.

    But there is one snag? The wife at this point in time will be sharpening the axe in the shed!

    Yes it could end up costing your life!

  2. #2
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    Stereo bass is certainly true. Stereo sub bass........it depends really. I have 2 pair of 2235's in 10 cubic foot cabinets, 2 at the front of the room and 2 behind the listening postion on the back wall. If I turn either pair off I cant really tell where the sub bass is coming from. I have them crossed over at 80Hz. If the subs are crossed over higher then you can hear the normal bass frequencies and they are directional.

    As for "burn in"........Speakers? I guess so. Electronics? Top end stuff I doubt very much. I should have been burnt in in the factory. Low end stuff.....maybe. As for cables.....I don't think so Tim! After you have passed a current through a peice of copper does it change into something else or is it still copper? There are 36, I think, isotopes of copper. Most are radioisotopes and have a half life of seconds or minutes. Two are stable. There isn't a lot that one can do to change the molecular structure of a metal with the output from a humble amplifier. Maybe a realy big amplifer would make a difference? More likely one would need a nuclear reactor of some type..........

  3. #3
    JBL 4645
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    Thanks Allanvh5150 I was kinder of skeptic at first thinking it wouldn’t work.

    I tried a few things as of late this afternoon by facing the JBL control 5 inwards at each other and crouching down in-between while I set the crossover at 80Hz -24db L-R then at 100Hz on the high pass end. I set the low end at -24db L-R with HF and centre muted I listened to some of the bass moments from Apollo 13.

    I could hear some notes moving from side to side and some equal tones as there is centre phantom bass within the left and right signal path.

    Also how have you solved the problem with each corner sub as there will be differences in peaks and dips, with independent EQ for each sub?

    That is how I’d tackle if I had matching arrays of subs lined along the length of the room to give even possible strength and reinforcement and uniform control.

    Yes it would cost a few bob or two, I would imagine hundreds of pounds and that is on the cheap side.


    How’s the weather down under warm?

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  4. #4
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    The weather down under has been hot, it hit 40 degress a few times. We have rain now and its a nice releif. My subs all run mono. The left and the right channel are summed and output to tha amp with overll EQ. I run my subs front and rear so they are not in the corners and I don't have that issue.

  5. #5
    JBL 4645
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    Lucky bugger mate 40!

    Hmm so would you say multiples would be too much lined up along the sides of the room?

    Two for each corner seems reasonable enough.

  6. #6
    JBL 4645
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    Popped out this evening to see friend but it was unfortunate it wasn’t the right time. I think he had a bird in with him?

    So I popped over to another friend said happy New Year and we talked about various topics. He’s speciality is electronics. He teaches it at school. Also he has pet cat called Rose named after Rose Titanic as someone was going toss the cat into river and they saved the cat.

    I mentioned my, misshape with Sooty and he showed sorrow and placed a small donation so I can pass onto the (PDSA) tomorrow.

    Anyway we chatted about stereo sub bass in brief he was confused at first as he only uses one single sub. But it wasn’t too long before he was way ahead of me.

    The differences in time arrival if a BOOM happens over on the right side!?

    Time it takes to reach one ear followed by the other ear with a delay of milliseconds.

    He was fixed to the idea but I think he likes lighting effects and showed me some of his latest projects.

    A strobe LED (white LED) looked fantastic with the light turned OFF. The resistor got so hot you could hear the hiss when wetting the finger and tapping it! It even marked the kitchen table with small hole.

    So now I’m thinking of LED and stereo sub bass and my cat of course.

    I guess you can delay each sub with Behringer product to give some kind of openness to the sound? Is it not possible to do this with certain frequencies as some tend to be large than others within the four-walls of the home?

    Quote Originally Posted by Allanvh5150 View Post
    Stereo bass is certainly true. Stereo sub bass........it depends really. I have 2 pair of 2235's in 10 cubic foot cabinets, 2 at the front of the room and 2 behind the listening postion on the back wall. If I turn either pair off I cant really tell where the sub bass is coming from. I have them crossed over at 80Hz. If the subs are crossed over higher then you can hear the normal bass frequencies and they are directional.
    Hmm weird that twice in the past 24 hours this JBL has come to my attention now.
    http://www.jblpro.com/pages/components/2235h.htm

    I gather it’s not too costly?


    Also guys I was thinking of placement of subs in the ceiling! Oh no this will never happen hare with dozens of holes cut-out with what ever size fitted into the hole.

    Well maybe a few for each corner. Wouldn’t the bass radiate evenly? Also would it mean less hassle with EQ adjusting for each or would the same problems exist?

    Also securing each one to prevent rattles and buzzes of a sort.

  7. #7
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    I picked up good frames of ebay a while back. I think they cost me $50 each. I got recone kits for them from the local JBL importer and dropped the new kit in myself. Total cost per speaker was about $350NZ which is about 135 sterling I think. I decided to keep them away from the corners of the room to get a flatter response. I have 4 of them driven with 2000 watts so not having the added corner response isn't a problem.

  8. #8
    JBL 4645
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    Quote Originally Posted by Allanvh5150 View Post
    I picked up good frames of ebay a while back. I think they cost me $50 each. I got recone kits for them from the local JBL importer and dropped the new kit in myself. Total cost per speaker was about $350NZ which is about 135 sterling I think. I decided to keep them away from the corners of the room to get a flatter response. I have 4 of them driven with 2000 watts so not having the added corner response isn't a problem.
    I think you know what I’m going to say???

    Scroll down the page…













































    Ł135,00 I’ll have to keep my eyes peeled. Thanks.

    Yeah but doesn’t placing them in the corners equal three boundaries what about mid-way up the wall in the corner it would be only two boundaries then?

    You must have larger…well almost large room sounds larger than mine?

  9. #9
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    My new room is under construction at the moment. It should be ready in about 4 weeks. Nearly all of the amps and speakers are built into the walls so I will have a nice clean room. It will also have floor to ceiling carpet so it should have the feel of a proper theatre. Speakers are, fronts L150A's, Surrounds L150's, Rears L86's, Rear sub 2x2235, front sub and center 2 x 2235, 1 x 2202, 1 x 2370/2425. Amplifier compliment will be Yamaha 7.1 amp that will be used for processing only, 1 ZPE 1000 1000watts per channel for subs, 1 ZPE 600 500 watts per channel for the fronts, 1 Perreaux PMF1150 200 watts per channel for the center and I am not sure how I will drive the surrounds yet. Also in the racks there will be vintage Roland 31 band graphic EQ's. Most of the gear is vintage and that is how I want to keep it. You have probably not heard of ZPE amplifiers before but they are identical to the Perreux gear, also made in NZ, They are an unknown gem and can be picked up very cheaply. The monitor that I will be using is an LG 50" plasma. As soon as I am done I will post some pics. I cant wait!!!

  10. #10
    JBL 4645
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    Okay a bit extreme! 30! For the home.

    Each would have to have its own amp and own PEQ to adjust the defences from

    Sub 1 2 3 4 5 6 7 8 9 10 (each left and right sidewall)
    Sub 1 2 3 (each left and right front)
    Sub 1 2 3 4 5 (each left and right rear)

    All with there own PEQ to adjust the levels to the sofa and a few feet in-front behind and to the sides of the sofa to be within normalize SPL db.

    What I’ve noticed is the wavelength of some frequencies depending on where the sub is located and the listen will have less at certain low tones and more at upper higher low tones this far too high for taking or is just in the wrong place.

    If sub 1 left produces tones good enough between 20Hz to 30Hz then rising at 30Hz to 40Hz then dropping slightly though 40Hz to 53Hz then rising again and so and so up the scale.

    It would be rather costly with powered subs. A diy approach would work out cheaper for the sub box enclosure pre-made with its own off the shelf sub that is going to fit the enclosure parameters.

    The amps well that’s going to be costly!

    The PEQ well that also is going to be costly but at least you won’t be beating your head against the wall in the one practically pursuit for flat sub bass frequency response with an all-around uniform coverage.

    Yeah I would buy 30 boxes and 30 JBL 10” to 12” and fill the sides, front and rear floor with subs.

    Same SPL db applies for clam level on the whole stack!

    Now do I use a blend of LFE.1 sent to all subs at different levels and slightly below the LCRS level. Keep the left and right side sub bass from (front/rear with blend sent to forward and rear subs)?

    Multiple ways of doing but the goal is to get even all-around uniform coverage that has few if not no tendency have dips and bumps in the range if you where standing at the front or anywhere in the room, if possible.
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  11. #11
    JBL 4645
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    Quote Originally Posted by scott fitlin View Post
    Engineers have always told us we couldn't hear Left and right information with subs, and that monoing the subs would be better, performance wise. It wasn't, stereo operation just sounds better, and there was one benefit that mono sum sub bass did offer, mono sub bass didn't rumble like stereo sub bass does, with vinyl records and turntables. It wasn't enough of an issue for me to give up the increase in fidelity, using stereo subs over mono operation, though.

    IF one can afford, STEREO IS THE WAY TO TRAVEL!

    Well monaural on Dolby pro-logic as its sum of the centre phantom signal mostly with a little left and right but its hard to tell?

    Dolby digital well the LFE.1 is purely monaural, so not much to talk about that for the time being.


    I filleted the crossover down the DCX for left and right front with HF muted. I turned the crossover so that the tiny little control 5 will be getting 20Hz to 50Hz the eerier Danny Elfman Psycho98’ opening titles sounded weird. I want more but there is only so much these, little control 5 can take, in the low end. Normally the crossover is set at Bessel-24db 80Hz for now.


    Also at a long distance the stereo sub bass in room would sound defused defocused. On the sides of the listener it might be different matter.

    Standing or seated near to the fronts it might be yes! Standing back it will defocus and will no longer sound like stereo sub bass.

    I guess a good pair of headphones and place it on crossover network and filter them down to 20Hz to 40Hz and see how that sounds??

    Also other tones higher above say 20Hz to 40Hz will not mask the lower pitched tones so the upper portion will have to be lowered, rather than turning up the lower end to silly levels! Otherwise it wouldn't be a great effect on the ears?

  12. #12
    Senior Member eso's Avatar
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    Quote Originally Posted by scott fitlin View Post
    Engineers have always told us we couldn't hear Left and right information with subs, and that monoing the subs would be better, performance wise. It wasn't, stereo operation just sounds better, and there was one benefit that mono sum sub bass did offer, mono sub bass didn't rumble like stereo sub bass does, with vinyl records and turntables. It wasn't enough of an issue for me to give up the increase in fidelity, using stereo subs over mono operation, though.

    IF one can afford, STEREO IS THE WAY TO TRAVEL!
    Absolutely.

    My bass horns cross over from the mains at 65Hz and are quite flat for an octave down and then roll off gently with significant output to 20Hz. They were designed for the mains to sit inside the mouths of the basshorns to minimize the time difference between the bass and the midbass.

    There is a great deal of stereo information going on below 60Hz. Even listening to a Jazz quartet playing a ballad, with a mono sub you will hear a bass transient that then "pulls" into the sub on notes with sustain. With stereo subs the string bass will maintain it's position in the stereo image in such situations.

    People resist stereo bass for some reason: I guess the brainwash has been pretty effective.

    Just for giggles, hook up stereo subs and listen to the Beatles "Come Together". George Martin was a talented guy, and he has alot going on in the first octave in stereo...

    eso
    30Hz Bass Horns/K151, Custom Midbass/D130, 280Hz Round Tractrix/2440, Fostex T925a: Full range horn loaded bliss.

  13. #13
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    Quote Originally Posted by hjames View Post
    Somehow I doubt Mr. Fitlin is running multichannel movie audio around his Eldorado Sound system -
    from his many discussions here I rather suspect he's got audio only sources in that system -
    He's got Pro audio subs in that system, not movie soundtrack subs -
    so DVD or Bluray config issues are moot up there.
    So sorry, but when I went back and re-read the 1st post in this thread I realized I didn't see that it was about HT and theater sound.

    It's really wonderful that you put SO MUCH time into correcting EVERYONE, catching all the duplicate posts, screaming each time ANY spammer comes into the forum, and just in general, YOUR such a GREAT POLICE OFFICER of OUR Forum!

    I am deleting my post, as you so watchfully alerted me to my mistake! IS THERE ANYTHING ELSE I CAN DO FOR YOU THIS EARLY MORNING?

    Oh, and IF you send me your address, ill send you a box of TEXAS TOOTHPICKS, excellent treats.
    scottyj

  14. #14
    Senior Member jcrobso's Avatar
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    Very interesting!!!

    People are told that bass is omnidirectional so it doesn't matter where you put the sub woofer. I totally disagree with that!
    But most people don't have $$$ or the floor space to multiple subs and they just do with what they have. Did I mention that I hate HTIB!!!
    When I converted from stereo to 5.0 surround I didn't use a sub. Since my mains are JBL loaded "K" horns and my surrounds are JBL88 novas I run them all as full range, only the center is setup as small.
    I do like hearing bass from the rear channels when it's in the soundtrack, instead of coming from a front sub.
    The ideal would be that all of the speakers would be full range with a sub.
    How many times has JBL4645 show us low bass in the center and rear channels, that just gets shoved to the one lonely sub.
    And the person set his sub behind the couch it becomes useless.
    Oh well, so much for my rant!

  15. #15
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    I'v never had my home cinema setup with stereo subs.
    I ran a Velodyne HGS-18 in the front (DBX driverack 260) as a highpass low pass crossover from mains output (mains set as fullrange with no high pass on preamp) and just summed the two channels low pass as a mono output to velodyne.

    I just have a pair of Peerless 12" woofers and plate amps...maybe i should give it a go with my 2ch setup.

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