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post #61 of 204 Old 01-11-2014, 04:03 PM
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Quote:
Originally Posted by splotten View Post

It is the LFE channel. As stated, I have used Taudioconverter. It uses FFmpeg to convert to multi channel wav. I looked into to the issue a bit since posting that screenshot and it appears that it might only be the core portion that is actually converted. If any filtering is applied, it is done "behind the curtain" in the sense that I haven't applied anything on purpose or am aware that it happens. If FFmepeg applies filtering as a default setting that might be the reson. I have no other explanation for the discrepancy between my conversion and follgotts, but I have listened via headphones to that particular track as a solo track and i cant detect any artifacts or weird sounds. If I play all tracks at once, as a stereo mix, audacity clips it and it will sound bad.

Here is the encoding summary if that helps:

[29-12-2013 13:55:14] ----Encoding Summary----
[29-12-2013 13:55:14] -Number of processes: 2
[29-12-2013 13:55:14] -Copy tags: True
[29-12-2013 13:55:14] -Use custom tags: False
[29-12-2013 13:55:14] -Enable artwork: False
[29-12-2013 13:55:14] -Copy artwork to output: True
[29-12-2013 13:55:14] -Copy external artwork: False
[29-12-2013 13:55:14] -Download lyric: False
[29-12-2013 13:55:14] -Add encoder suffix: True
[29-12-2013 13:55:14] +Audio
[29-12-2013 13:55:14] -Encoder: Wav
[29-12-2013 13:55:14] -Bit Depth: Original
[29-12-2013 13:55:14] +Effects
[29-12-2013 13:55:14] -Disabled
[29-12-2013 13:55:14] Temp: C:\Users\'''\AppData\Local\Temp\TAudioConverter\
[29-12-2013 13:55:14] Output: C:\Users\Downloads\hd_thx_amazing_life_lossless.part2\hd_thx_amazing_life_lossless2
[29-12-2013 13:55:14] ----Encoding Summary----

As far as i can tell there is no clipping protection when Effects is disabled.

Its the loss less version found here:

http://www.demo-world.eu/trailers/high-definition-trailers.php

... And sorry for even more OT :-)

BTW. Amazing results FollGott. smile.gif

I found the difference, The ArcSoft DTS decoder doesn't apply the 120Hz lowpass. When I add a 24dB/oct lowpass at 120Hz, my waveform looks nearly identical to yours.

Also, the trailer available at demo world is not identical to the one from the Star Wars BD.

JSS
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post #62 of 204 Old 01-13-2014, 05:01 AM
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OK. Thanks. Im amazed a low pass is required to avoid clipping. Of course i dont know your setup but it might be wort while applying a Low pass before converting to analog, as digital clipping causes artifacts. Have you tried capturing the analog output with and without A LPF?

Here is a capture of a 80Hz tone and a 200Hz tone. First played separately and the together, causing digital clipping in the playback software.

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post #63 of 204 Old 01-13-2014, 02:49 PM
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The genelec website states that DTS-HDMA decoders apply a 100Hz 60dB/octave lowpass. I find this cannot be true, here is my 'proof' (from a PM conversation exploring this very thing).

More research on my part has uncovered this:

Two films which have HUGE effects at over 140Hz are Transformers:Revenge of the Fallen and Thor. Both have DTS-HDMA tracks. Neither of them has a lowpass applied when decoded by the AVR in my system, and those effect(s) are some of the loudest in the film(s). If a 60dB/octave lowpass was in place at 100Hz, those effects would be many more dB down.

Thor (142Hz):





TF2 (just over 120Hz, encoded to play back at just over 118dB):





These digital grabs match the analog grabs from the decoder in the AVR. No 100Hz 60dB/octave lowpass there...

I think there are sloppy mixers and good ones. Most everyone has a lowpass built into their sub amp or receiver, and I'm sure the mixing stage does the same, so square waves would appear much smoother. I set my LFE lowpass at 200Hz on my playback equipment to capture just such events as the ones above.

I could be wrong. But as far as I know, the existence of good, non-square-wave containing tracks (Tron Legacy's LFE channel has zero clipping), it makes me think it is a production mistake, not a decoding mistake, which is blinded by the lowpass filters on AVRs and subwoofer amps.

JSS
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post #64 of 204 Old 01-13-2014, 06:22 PM
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Quote:
Originally Posted by maxmercy View Post

I set my LFE lowpass at 200Hz on my playback equipment to capture just such events as the ones above.

What equipment?

I've never seen LFE LP with a selection above 120 Hz.

Noah
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post #65 of 204 Old 01-13-2014, 09:50 PM
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Denon 2809ci.

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post #66 of 204 Old 01-14-2014, 03:02 AM
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Quote:
Originally Posted by maxmercy View Post

The genelec website states that DTS-HDMA decoders apply a 100Hz 60dB/octave lowpass. I find this cannot be true, here is my 'proof' (from a PM conversation exploring this very thing).

More research on my part has uncovered this:

Two films which have HUGE effects at over 140Hz are Transformers:Revenge of the Fallen and Thor. Both have DTS-HDMA tracks. Neither of them has a lowpass applied when decoded by the AVR in my system, and those effect(s) are some of the loudest in the film(s). If a 60dB/octave lowpass was in place at 100Hz, those effects would be many more dB down.

Thor (142Hz):





TF2 (just over 120Hz, encoded to play back at just over 118dB):





These digital grabs match the analog grabs from the decoder in the AVR. No 100Hz 60dB/octave lowpass there...

I think there are sloppy mixers and good ones. Most everyone has a lowpass built into their sub amp or receiver, and I'm sure the mixing stage does the same, so square waves would appear much smoother. I set my LFE lowpass at 200Hz on my playback equipment to capture just such events as the ones above.

I could be wrong. But as far as I know, the existence of good, non-square-wave containing tracks (Tron Legacy's LFE channel has zero clipping), it makes me think it is a production mistake, not a decoding mistake, which is blinded by the lowpass filters on AVRs and subwoofer amps.

JSS

You are most likely right about production errors. Even if all info on the LFE channel is not always consistent there seem to be consensus the that upper end of the LFE channel is ~120Hz. Still some movies has content way above that. In my AVR i cant adjust the LFE low pass but i believe the correct setting is 120Hz, in the sense that 120Hz is the best compromise between the various movie sound formats. You have set the LFE LP at 200Hz, that is most likely the reason you see the big effects above 120Hz.
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post #67 of 204 Old 01-14-2014, 02:25 PM
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I agree that consensus is 120Hz, but the effect in Thor was quite palpable and VERY effective. Since Dolby and DTS decided to make them full-bandwidth channels, I set my lowpass higher on my AVR.

JSS
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post #68 of 204 Old 01-14-2014, 02:46 PM
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I have my Onkyo set for 120hz with 100hz and 80hz as alternative options. The spec for LFE is up to 120hz so that's where I'm setting the filter. wink.gif
Quote:
Originally Posted by noah katz View Post

What equipment?

I've never seen LFE LP with a selection above 120 Hz.

My previous AVR was a Harmon Kardon 525 that had the ability to go up to 200hz, IIRC.


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post #69 of 204 Old 01-14-2014, 03:05 PM
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Quote:
Originally Posted by maxmercy View Post

I agree that consensus is 120Hz, but the effect in Thor was quite palpable and VERY effective. Since Dolby and DTS decided to make them full-bandwidth channels, I set my lowpass higher on my AVR.

JSS

Yes, the newer HD formats is full bandwidth in the LFE channel. However it is my understanding that they are not meant to be played back like that. The older formats (should) have the LFE filtered in production end and Dolby HD and DTS HD should have the LFE filtered in the playback end. Of course if you like a higher 200Hz LP better, then that is just fine.
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post #70 of 204 Old 01-14-2014, 05:11 PM
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Unfortunately, I can find no quotable source for the proper frequency and slope for the LFE lowpass recommended by Dolby or Digital Theater Systems. But there are plenty of AVRs with user- settable LFE lowpass.

Do you know of a technical paper or spec that has the proper freq and slope?

JSS
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post #71 of 204 Old 01-14-2014, 11:23 PM
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Unfortunately not. Its all second hand information. Its very annoying that its not possible to obtain the the technical papers containing the specification for intended playback settings and routing, but it seems you actually have to pay Dolby if you want them. Unfortunately it leads to much confusion and endless debates over simple matters that could be sorted in minutes if the spec were freely available.
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post #72 of 204 Old 01-15-2014, 01:12 AM
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max, splot, i concur.

one document that I've found is the atmos theater spec. attached. not quite what we are looking for, but it does have some minimal specs.

Dolby-Atmos-Cinema-Technical-Guidelines.pdf 1507k .pdf file
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post #73 of 204 Old 01-15-2014, 01:27 AM
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ah!

http://www.pacificav.com/library/Dolby%2051%20productions%20guidelines.pdf

section 3.3 has some good info on bass management for 5.1 systems.

"When utilizing the LFE channel in a mixing situation, it is important to band-limit the
information for this channel. In the Dolby Digital encoding process, the encoder will
brickwall filter the LFE signal at 120 Hz. To properly hear the LFE content, a sixth or
seventh order 120-Hz low-pass filter must be included in the monitor chain. It is
advisable to include this filter in the console output before the monitor such that both the
recorded information and the heard information are band-limited. Failure to include
this filter will result in hearing substantial bass information above 120 Hz in the mix
that will not be present in the Dolby Digital encoded version. 120 Hz is the proper
crossover frequency for theatrical film applications."

Dolby51productionsguidelines.pdf 2942k .pdf file
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post #74 of 204 Old 01-15-2014, 05:08 AM
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I have seen this filter applied in the encoding process for DD, on the Transformers DVD and other DVD titles. I wonder if the spec has changed for monitoring the lossless formats or not....probably not. Wow, 6th or 7th order.....

Thanks for the link. Through all of my measurements, I find that most films do apply a filter to the LFE channel upon encode even on the lossless formats, but I really like it when some >120Hz info is played back at high level, it can really add to a scene if judiciously used, like the 2 examples above (the average graphs do not deviate nearly as much as the peak, both effects are singular in their respective films).

JSS
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post #75 of 204 Old 01-17-2014, 12:35 PM - Thread Starter
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Since I my floor is made of conrete I didn't feel any vibration even at the highest SPL. There were just so tactile information. Now the situation has changed!

I build a riser with spring isolators for heavy machines. I calculated the target weight and bought 6 of these damped spring isolators.



Wow! This is a big difference! Now I can feel the monster in "Cloverfield" when it walks through the skyline of New York. Very cool!

It is very important that the riser is sealed. Sound pressure moves the plate when it is on one side only. I tried it without the rubber and I felt nothing. I can not describe how big the difference is.




Then I measures world's first riser frequency response with my laser distance sensor.cool.gif



As you can see amplitude response is pretty good. The resonance frequency of the empty riser is at about 12 Hz. Of course it will be smaller when there are persons and a couch on it.





It feels very natural and subtle. With shakers I always found the effect too much and too unnatural or "slow". With the passive riser the vibration come at the same moment when sound pressure arrives. Perfectly in time.

One drawback: humans feel acceleration and not amplitude. Since acceleration increases with frequency the tactile effect increases with frequency, too. To feel all the low frequency with the same amount the amplitude response must be a falling line. But with a passive riser this can not be changed. Maybe I'll experiment a bit more with the Quake 10B. But now I'm very happy with the result! smile.gif

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post #76 of 204 Old 01-17-2014, 12:46 PM
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neat!

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post #77 of 204 Old 01-17-2014, 12:55 PM
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Quote:
Originally Posted by FoLLgoTT View Post

It is very important that the riser is sealed. Sound pressure moves the plate when it is on one side only. I tried it without the rubber and I felt nothing. I can not describe how big the difference is.

Nils, do you use the rubber mat curtain to "seal" the riser?
thank you very much
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post #78 of 204 Old 01-17-2014, 01:32 PM - Thread Starter
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Quote:
Originally Posted by zheka View Post

Nils, do you use the rubber mat curtain to "seal" the riser?

Yes. Without the rubber mat the sound pressure is equal on both sides of the plate and nothing moves. At the moment it isn't even completely sealed. But it is enough to have a noticeable effect. smile.gif
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post #79 of 204 Old 01-17-2014, 01:47 PM
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Awesome!

Do you think this would would work over carpeted floor? as you said, the seal does not have to be airtight...

Also, do you think spring based isolation is essential to achieve the effect or this is something that can be done using absorbers like Auralex floor floaters ?
http://www.amazon.com/Auralex-U-Boat-Floor-Floater/dp/B0002IL6ZS

Thanks!
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post #80 of 204 Old 01-17-2014, 02:26 PM
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Quote:
Originally Posted by zheka View Post

Awesome!

Do you think this would would work over carpeted floor? as you said, the seal does not have to be airtight...

Also, do you think spring based isolation is essential to achieve the effect or this is something that can be done using absorbers like Auralex floor floaters ?
http://www.amazon.com/Auralex-U-Boat-Floor-Floater/dp/B0002IL6ZS

Thanks!

I believe the point is to have a mass that can actually move when a force a light force is applied to it. Imagine standing on the ground and I push you "very very softly". You won't move. Might not even notice it. That is why people buy butt-kickers, etc. They need a strong force to physically "shake them". But what happens if you were standing on ice with Teflon shoes. I could push you ever so softly and you would feel in your body as you moved. This is what I feel FoLLgoTT did. He made so movement of air could move his rise" enough to get that tactile feel. Brilliant move. Honestly, f'ing brilliant. But, you do need his kind of system to generate that SPL force to cause the movement. Secondarily, you don't want too many springs or you just land up being stiff again.

As a FYI, you can buy systems like this already. You put three moveable masses (rubber pucks) on 3 of your 4 corners of a chair/sofa and then a small linear actuator on the other. I believe Japan Dave did this. But FoLLgoTT did it much more cost effective on a larger scale using his subs to generate the force. Super props!

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post #81 of 204 Old 01-17-2014, 02:50 PM
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Quote:
Originally Posted by FoLLgoTT View Post

Maybe I'll experiment a bit more with the Quake 10B.

Yes, please do so. EQ and delay might make a significant difference.

Thanks for posting your results with the resonating floor.

Markus

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Quote:
Originally Posted by Trepidati0n View Post

I believe the point is to have a mass that can actually move when a force a light force is applied to it. Imagine standing on the ground and I push you "very very softly". You won't move. Might not even notice it. That is why people buy butt-kickers, etc. They need a strong force to physically "shake them". But what happens if you were standing on ice with Teflon shoes. I could push you ever so softly and you would feel in your body as you moved. This is what I feel FoLLgoTT did. He made so movement of air could move his rise" enough to get that tactile feel. Brilliant move. Honestly, f'ing brilliant. But, you do need his kind of system to generate that SPL force to cause the movement. Secondarily, you don't want too many springs or you just land up being stiff again.

As a FYI, you can buy systems like this already. You put three moveable masses (rubber pucks) on 3 of your 4 corners of a chair/sofa and then a small linear actuator on the other. I believe Japan Dave did this. But FoLLgoTT did it much more cost effective on a larger scale using his subs to generate the force. Super props!

It looks like Nils built a giant passive radiator, with suspension and rubber surround smile.gif
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post #83 of 204 Old 01-17-2014, 05:18 PM
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Tremendous idea and implementation, and simple to boot! Wow.

JSS
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post #84 of 204 Old 01-17-2014, 06:04 PM
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Quote:
Originally Posted by FoLLgoTT View Post

Since I my floor is made of conrete I didn't feel any vibration even at the highest SPL. There were just so tactile information. Now the situation has changed!

I build a riser with spring isolators for heavy machines. I calculated the target weight and bought 6 of these damped spring isolators.



Wow! This is a big difference! Now I can feel the monster in "Cloverfield" when it walks through the skyline of New York. Very cool!

It is very important that the riser is sealed. Sound pressure moves the plate when it is on one side only. I tried it without the rubber and I felt nothing. I can not describe how big the difference is.
Warning: Spoiler! (Click to show)



Then I measures world's first riser frequency response with my laser distance sensor.cool.gif



As you can see amplitude response is pretty good. The resonance frequency of the empty riser is at about 12 Hz. Of course it will be smaller when there are persons and a couch on it.





It feels very natural and subtle. With shakers I always found the effect too much and too unnatural or "slow". With the passive riser the vibration come at the same moment when sound pressure arrives. Perfectly in time.

One drawback: humans feel acceleration and not amplitude. Since acceleration increases with frequency the tactile effect increases with frequency, too. To feel all the low frequency with the same amount the amplitude response must be a falling line. But with a passive riser this can not be changed. Maybe I'll experiment a bit more with the Quake 10B. But now I'm very happy with the result! smile.gif
Hi FoLLgoTT, mind sharing how much you bought the damped spring isolators? would a rubber isolator provides the same effect? can you please sharing more pictures of your riser?
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post #85 of 204 Old 01-17-2014, 08:21 PM
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Passive shaker... cool.

Wonder if eq and time delay could solve you problem with active shakers...?
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post #86 of 204 Old 01-17-2014, 11:53 PM - Thread Starter
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Quote:
Originally Posted by zheka View Post

Also, do you think spring based isolation is essential to achieve the effect or this is something that can be done using absorbers like Auralex floor floaters ?
http://www.amazon.com/Auralex-U-Boat-Floor-Floater/dp/B0002IL6ZS

I cannot answer your question, because I never tried rubber isolators.
Quote:
Originally Posted by WereWolf84 View Post

Hi FoLLgoTT, mind sharing how much you bought the damped spring isolators? would a rubber isolator provides the same effect? can you please sharing more pictures of your riser?

The spring isolators are pretty expensive. One of them costs about 60 €.
They have a nominal range in which the damping material touches both plates. So the weight has to be calculated correctly.





Here are moe pictures of the riser. The construction is very simple. There is a frame of wooden beams with chipboards on it. Everything is glued and screwed to avoid creaking sounds. There are 3 spring isolators on the front side and 3 on the back side. They are directly screwed on the board.




Quote:
Originally Posted by zheka 
It looks like Nils built a giant passive radiator, with suspension and rubber surround

Yes, this is exectly the idea behind my riser. smile.gif

I made a bunch of experiments with my prototype subwoofer.


Experiment 1

I wanted to know how things get stimulated by the sound pressure. So I connected a driver to an oscilloscope. When the cone of a driver is moved externally it acts as a generator. So you can measure the voltage with an oscilloscope and analyze the amplitude.
So I measurend different alignment with the raw driver. The sound pressure of the SBA comes from the front. As you can see the driver moves most when it is parallel to the front and least when it is orthogonal to it.

0°:



30°:



45°:



90°:




Experiment 2

Then someone gave me the hint to seal the back of the woofer, because with the naked driver the pressure is the same on both sides. So I took the old prototype enclosure and did the measurement.

0°:



90°:



Amplitude stays nearly the same. With this finding I built my riser! smile.gif
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post #87 of 204 Old 01-18-2014, 03:21 AM
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And with the large surface area of the riser, small changes in room pressure create large forces. Great idea, thoughtful and innovative build all around. Look forward to seeing the finished room.

Do you note any resonances within the riser? It looks to have a large suspended center area that could generate non-trivial amounts of flex. Or is the seating going to be mainly supported by front and rear edges near the damped springs?

Second question: With all seating in place can you still feel the riser move easily?

JSS
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post #88 of 204 Old 01-18-2014, 07:21 AM
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Great idea!

What is the consistency of the center rubber/plastic piece? Wonder if valve springs from a muscle car are about the right strength???

Paul W

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post #89 of 204 Old 01-18-2014, 12:03 PM - Thread Starter
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Quote:
Originally Posted by pnw View Post

What is the consistency of the center rubber/plastic piece?

It feels like some kind of foam. But it is very stiff.


@all
Today I did a few measurements with a Quake 10B. I mounted this shaker on the board and took measurements with the laser.



First I opened the Quake 10B and measured the oscillating weight directly. As you can see its amplitude response is pretty linear. Overall it looks good. Now I know how the riser is driven.
Note: my signal path is linear down to about 3 Hz.

Quake 10B (oscillating weight):


Here are measurements of the riser with 0, 1 and 2 person(s).

Amplitude responses with different weights (0, 1, 2 person(s)s):


Empty riser:


1 person:


2 person:


This looks pretty bad! The resonance frequency at about 12 Hz is dominant.

It is rather interesting to see that the resonance frequency increases with weight! I assumed the opposite. Ihave the thesis that the damping material inside the springs changes the whole system when getting compressed. The waterfall diagram shows that decay time decreases with weight. So the resonance becomes damped more and more. This may confirm this thesis.

I could equalize frequency response, but since it dramatically changes with the number of persons I would need 3 presets. And the shaker still feels unnatural. It is different to the passive riser. Of course the shaker is much stronger, but one has to like it. I have to think about using it or not...
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post #90 of 204 Old 01-18-2014, 12:57 PM
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Nils is my latest favorite poster. cool.gif

I would like to know what difference there would be if the floor was suspended by blocks at the perimeter with no springs.

I wonder if you can tell the resonant frequency of my wood frame floor system in my HT space?



As I've said in other threads on this subject, it doesn't take much movement underneath you to leap to a whole new experience in movie watching. smile.gif

I also was involved in the discussion years back where some claimed that a resonance could cause a cancellation at that frequency, explaining Ricci's FR suckout around 10 Hz. I argued for proof because I'd never heard of that in anything I read on the subject. When a resonance is externally excited, the result is always a magnitude increase, never the opposite. The increase is also seen above and below the resonance, not just at the resonance frequency. Also, the effect can be seen in multiples of the resonance frequency, as the evidence suggests in your graph. The resonance can be partially excited by higher harmonics of the fundamental excitation frequency and multiples of the resonance frequency can be excited by the fundamental excitation frequency.

Way too cool stuff. I suggested in another thread that riser construction will soon become a standard procedure with different methods resulting in different predictable results.

This puts a whole new light on the subject.

What was the formula you used for calculating the weight to spring isolators?
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