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MisterVego

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Posts posted by MisterVego


  1. 5 minutes ago, Chris A said:

    Once you see how it works...and do it a couple of times...it's like riding a bicycle. 🚲  You'll never will go back to using canned crossover filters either once you hear the difference.  The sound quality difference isn't close.

     

    This little process works fairly fast if you're in-room and can make observations on measurements and make immediate adjustments, then rerun the sweep.  You'll have to check that you've got the driver polarity right ( :laugh: ).  Make sure that there's plenty of absorption on the floor and nearby walls before you start the process--at least a couple inches thick and several feet wide, all the way to the microphone from the loudspeaker under test/adjustment.

     

    Chris

    I'm looking forward to loading the latest revision then walking though the steps again to see the effect on each change.

    Once i get this other issue straightened out, I'll be all over it...   

    -e


  2. 3 minutes ago, Chris A said:

    IIR filters only--no "named" crossover filters, i.e., Danley-style. 

     

    Look at the raw response of your drivers/horns.  Without FIR filtering, you can't improve on the response that you see there after they've been EQed flat (individually).  So you need to select drivers and horns that have good phase response characteristics.  It just so happens that the Jub bass bins and TAD 4002/K-402 horns have really good phase response taken individually--after they've been EQed flat by themselves.

     

    So all you have to do is put the HF and LF drivers together without phase shifts:

    1. Don't use the "crossover filters" that come with DSP crossovers--clear any crossover filters if they're set.
    2. Set the HF or LF channel delay to get perfect impulse response in the time domain--as seen in the spectrogram view.
    3. Flatten each driver's SPL response within their pass bands.
    4. Match the channel gains between flattened phase drivers.
    5. Use output channel PEQs to trim off response on each end of the bass and high frequency drivers until you've got overall flat SPL across the crossover interference band and smooth handover of SPL vs. frequency.  The drivers themselves will tell you where that transition/crossover should occur.  [If you're using MEHs, you'll have to use multiple PEQs to attenuate the bass bin peaks in response above the first notch frequency.]
    6. Use the input PEQs to further flatten the overall response within the interference band to correct any dips or peaks in response within that band.

    Voila!  Flat phase.  It's really that easy.

     

    Chris

    Chris, you make it sound easy  ;)

     


  3. On 5/26/2019 at 11:47 PM, Khornukopia said:

     

     

    It is a bit curious. For the sake of eliminating any test equipment variables, have you measured any other subs 20Hz signals lately?

    This is the first subwoofer I've owned in about 20 years....


  4. 2 hours ago, Khornukopia said:

     

    I like the symmetry of your arrangement, but for the sake of diagnosis, have you tried playing your sub woofer tucked into the corner? 

    Thanks @Khornukopia

    I have not.  "tucking" this sub anywhere is not really an easy thing to do....  But it is one of the things i'm going to be testing PRIOR to completely filipping the room around so the speakers and the subs are on the same wall and so i can get atleast 14' away from the sub..

     

    I am still have my doubts since its current placement is considered 1/4 placement and Roy has mentioned it should be digging deeper. 

     

    What i'm confused with is if the sub is "supposed" to have a lower frequency response shouldn't that be seen with a sweep when the mic is at the mouth of the horn?   When i did a sweep, at the horn mouth, still 30hz fall off...


  5. 20 hours ago, mikebse2a3 said:

    Erik I understand and here is a couple of thoughts for you to try if you haven’t already. 🙂

     

    If you still have the 32hz peq boost on the Jubilee try bypassing it and see what happens.

     

    I would also experiment with rolling the Jubilee off in the region that you are using the 1502 to see how that changes the response at the Listening position.

     

    miketn

    @mikebse2a3   So last  night i DID remove the slight 32hz peq boost on the Jubes.  I also applied a high pass on the Jubes at the xover frequency.   

    The end result eliminated the sharp dip at 40hz.  I would assume the previous dip was due to the  colliding tones from the sub and the jubes.

     

    BUT.....    Regardless....   I have a hard drop at 30hz....   I am still under the assumption that either my room is tuned to that frequency and things drop off steeply at 30hz at my listening position...   OR....   I need to get further away from the Sub allowing it to fully develop.

     

     


  6. 6 hours ago, Khornukopia said:

     

    Yes the mineral wool insulation does function properly as a bass trap while sealed in the bags. The plastic shrink wrap is not a barrier to the long wavelengths of the bass frequencies. It is actually recommended that bass traps should have a thin hard surface to reflect the high frequency energy, if you don't want a broadband absorber.

    @Khornukopia     Have got some 8" cornertraps on the same end as the sub.   These traps also contain a surface membrane to reflect HF waves....

     

    I've heard the insulation bale trick works too....   However, I'm still skeptical that trapping is going to help in this situation.   From what i read to tame frequencies below 40hz require HUGE traps....

    Erik Room.jpg


  7. But what i'm really confused with is how can some people with smaller rooms, smaller subs get room responses down into the teens..

     

    I must be missing something.....

     

    ( I would like to stress, i am NOT looking for a response in the teens)


  8. 2 minutes ago, babadono said:

    The wavelength of a 20Hz sound wave is 17 meters. So 4 meters is approx. a quarter wavelength. Just sayin'

     

    I'm picking up what your throwing down...... 

     

    I'm at the limits of what my room can actually produce.  My seating position just happens to be at a low point and once I get further to that 1/4 wavelenth point I can start to get more gain at that frequency.

     

    Long short of things... Sub is working correctly,  needs MUCH MORE space to really come alive and to get down to that freq range naturally I need to be sitting towards the back of the room with the sub facing me.....


  9. 45 minutes ago, mikebse2a3 said:

    Erik I understand and here is a couple of thoughts for you to try if you haven’t already. 🙂

     

    If you still have the 32hz peq boost on the Jubilee try bypassing it and see what happens.

     

    I would also experiment with rolling the Jubilee off in the region that you are using the 1502 to see how that changes the response at the Listening position.

     

    miketn

     

    Just now, mikebse2a3 said:

    Erik you will probably need to readjust your Sub settings when you change the Jub settings I have suggested you try.

     

    If the suggestions lowers the peaks in the 30hz region then I would try to rebalance the Sub by turning up the sub channel level from the xilica and use more cuts than boost peqs or possible shelves adjustments.

     

    miketn

    Mike,

     I will try doing  both of your suggestions.  It'll be interesting to see what changes.

     

    However.   With my recent tests.   I have not been activating the Jubes.   The sweeps and test have been with the sub only.

     

    From what Chris mentioned in Adams thread, it seems as if my room has a transition frequency of 29hz....   This is seems to coincide with the 30hz drop i'm seeing in the raw data @ listening position.      

     

    When running the sweep (sub only) 4m/13'' from the face of the sub, that dip from 30hz moved down to the low to mid 20hz region.     Is this essentially what people describe as room gain?

     

     


  10. 36 minutes ago, mikebse2a3 said:

     

    Question:  If a person were standing in front of the sub on the ground outside with no reflection from near by structures would distance from the sub matter..?  

     

    miketn

    I would say no since there are no reflections for the sound waves to bounce back creating a null?

     

    Mike, as you know I am still learning the fundamentals when it comes to this stuff...     I guess what i'm finding is that it is my room causing the sub from producing its full potential?  Seems like this room is limited by a natural 30hz freq....  maybe a little more with boosting and then a little more due to room gain once i get around 4m from the speaker?

     

    Mind you, i am not complaining or trying to get into the single digit / teens with a response, I am just trying to understand whats going on here and calm some of my OCD thinking i'm doing something wrong.

     

    -e

     

     


  11. 6 minutes ago, Chris A said:

    What is the longest dimension of your listening room?  This will determine the transition to "pressure zone" region or band.  In my room, that transition happens at ~14 Hz...calculated using:

     

         1132 ft/sec / (2*39.5 feet))--a half wavelength calculation. 

     

    Above this frequency band, you've got the "sparse mode region" of the room (usually up to 100-300 Hz, depending on room volume and reverberation time), and above that, the "dense mode region".  At the commercial cinema scale, there is no real "transition to pressure zone" due to the room's dimensions since they are quite large by comparison to home hi-fi sized rooms.

     

    Chris

    My Room is 19'6" L  x 14' W x 9'H


  12. I've been doing some testing the last couple of nights.

     

    It seems as if you need to be at least  4m away from the subwoofer to get a respond in the 20's  with out any PEQ boosting.

     

    While you can get a flat response down to 20hz at my listening position ( about 60" in front of the sub.  Sub is behind me) A significant amount of boosting and attenuation is needed.  When doing this the result is less overall SPL.... 

     

    So horn loaded vented subs need a significant amount of volume / distance for them to fully open up?    


  13.  

    Thanks to these forums Adam and I have become very good friends and we both have very similar setups:  Jubes & 1802/1502.

     

    After several weeks of chatting with Adam, sharing response curves and ideas, I'm starting to see a pattern. (some of you have seen the post I created with questions/concerns about the response of my 1502 sub.)

     

    The two subs seem to be VERY similar in response..  This has been mentioned before by Roy, i think he has mentioned that the 1502 is identical except 3db down.

     

    What i'm finding is that taking measurements at the sub mouth or somewhat nearfield ( my listening position is about 60" infront of the sub.  Sub is behind me like Mike Beasley has his)

    The sub naturally rolls off right around 30hz.     With some PEQ manipulation I CAN get a flat response down to 20hz but with sacrificing SPL.  

    Should subs like these create a lower response at the horn mouth?

     

    Last night i did some more testing and when running sweeps of the natural response of the sub ( no peqs) the response  did extend further down to the 20hz point once i was around 4m from the face of the sub.

     

    When  Roy mentions the 1802 will achieve mid teens in a Auditorium without boost.   Is this a direct result of needing a room with  enough volume to allow the sub to fully bloom those lower octaves while achieving the published SPLs?   If this is the case, it almost seems as if at 4m/13' distance from the sub face is the sweet spot  to get down into the 20s.   

     

     


  14. 5 minutes ago, mark1101 said:

    I didn't see anything wrong with the very first sweep. It was good to the mid 20s. That will loosen drywall in time

    @mark1101 not going to disagree with you however, just trying to have it a little smoother down to 20hz.

     

    Its pretty impressive how the sub flexes the walls in my dedicated room which build with double layered 5/8" drywall..


  15. 16 hours ago, babadono said:

    @MisterVego Are you trying to get the 1502 to dig a little deeper? @AHall has been doing port plugging tests on his 1802 to try and get it to go a little lower. Don't know if you've seen his thread.

    @babadono    Not trying to dig deeper than designed.  Just trying to get a flatter respond down to 20hz.   I don't think I'm being  greedy  since i have been told that the sub is capable of a sub 20hz response..

     

    As @AHall has mentioned we are friends and have been discussing the issues i am having.   His 1802 is capable of digging down to 20hz before his port mod.  I am not interested in modifying my sub in any way.  Just trying to determine if this is a PEQ issue or if its a modal issue in my room.  Since the 1502 is a rare beast and the 1802 is only in a few residential  environments I'm optimistic that the help of the experts in this forum can help me resolve the issue.


  16. 1 hour ago, Frzninvt said:

    It is not designed to have much if any useable output below 30Hz it's a theater subwoofer.  If you want solid output below 30Hz you need another subwoofer that is solidly capable of it without having to alter it.  I am sure it will pound your chest in the 40 to 60Hz range though it's just not going to give you the octaves below that though.  I run Velodyne HGS-18's which are far smaller and dig far deeper albeit with less overall output but that is what the La Scala's, Cornwall's, and four Heresy HIP's are for.

    Are you sure about that?    Quote from Mr. Bonehead himself when doing research on this sub... :

    "If you have room for them, the 1502 will take you below 20 hz and will match the clean bass of the jub lf.  I think the 1502 will shock you."

     


  17. 2 hours ago, Chris A said:

    Just remember that a 1/4 wavelength (90 degrees) at 40 Hz, room temperature,  is 7 feet, i.e., 6.25 ms.  So the summing of the sub/Jub bass bin at the crossover point is pretty insensitive to changes in delay values.  I'd go in steps of 3--6 ms to see changes in frequency response at 40 Hz.

     

    By the way, you're going to see a fair amount of harmonic distortion growth below 30 Hz if the sub behaves like the 1802.  It seems as if the real contribution of the 1502 or 1802 is their placement mid-wall such that it's filling up the mid-wall room modes with about the same bass extension as the Jub bass bins. 

     

    Chris

    Chris,

    I'll try playing with the delay again.

     

    I set my current delay by playing a 50hz ( my xover freq) tone and  separately matched levels of the jubes and the sub.

    I then reversed polarity of the sub and then played both the jubes and subs together increasing delay until the overall SPL was the lowest.  Once done a changed the subpolarity back to normal.

     

    Perhaps there is a better way to adjust this?  

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