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MisterVego

Jubes / 1502 No Bass below 30hz

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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.....

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Posted (edited)

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)

Edited by MisterVego

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The bass bouncing off the walls crosses paths with the direct bass arriving at your listening position and nullifies it. Same principle as noise cancelling headphones. I had a similar low frequency response problem because of the size and shape of my room. I fixed it by installing some bass traps. I bought some Rock-wool mineral fiber, sound and fire insulation, wrapped the bulky 15x24x48" bundle(s) in black fabric and placed them in the corners of the room. If you try this, save your receipts and leave the plastic wrap intact, in case you want to return the bundles of insulation because of how big they are. (Some people would buy more subwoofers, rather than fix the room modes with a large bundle of insulation.)

 

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Do those bundles of insulation perform fine while still sealed in their bags?

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9 hours ago, MisterVego said:

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)

 

What amazes me is how headphones can reproduce very low bass in such tiny spaces.  And yet they do.

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1 hour ago, Islander said:

Do those bundles of insulation perform fine while still sealed in their bags?

 

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.

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2 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.

Yes you are correct, another name for what you describe is a "membrane absorber". If the membrane seals the fibrous material so that the system is sealed and air tight then the system will be even more efficient. The longer the fiber and then more complex the tangle the greater the dissipation of energy. These work extremely well on the inside walls of cabinet especially reflex cabinet where you may want additional damping but the design requires that the volume of air must be free to resonate so that it may couple with and drive the vent.

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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

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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.

 

 

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5 hours ago, MisterVego said:

Have got some 8" cornertraps on the same end as the sub.

 

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

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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...

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Jubes in title, 3 pages later and still no pics of jube just lame freq plots and the seating position ...   Come on man!!

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12 minutes ago, Kalifornian said:

Jubes in title, 3 pages later and still no pics of jube just lame freq plots and the seating position ...   Come on man!!

@Kalifornian   Here ya go bro!

Jubes.jpg

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Nice 

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You're doin' the hang your 402 down a little and in front of the bass bin?

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1 minute ago, babadono said:

You're doin' the hang your 402 down a little and in front of the bass bin?

@babadono  good eye ;)

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On ‎5‎/‎23‎/‎2019 at 5:19 AM, MisterVego said:

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....

 

That is why I utilize the full bundles.

 

On ‎5‎/‎23‎/‎2019 at 1:09 PM, MisterVego said:

I 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...

 

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

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On 5/23/2019 at 5:10 PM, Kalifornian said:

What Mcintosh preamp are you using to run those? 

C2300

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