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post #3151 of 4726 Old 04-11-2015, 12:43 PM - Thread Starter
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Originally Posted by derrickdj1 View Post
I have been mixing sealed and ported for 3-4 years now in different room with good results. I brought an Omnimic in Dec. to prove it to myself, lol.
I believe you mentioned that your room behaves similarly in that below a certain freq, adjusting phase has little impact on the response?
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post #3152 of 4726 Old 04-11-2015, 12:59 PM
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Can the vibration app be calibrated somehow, I doubt anyone has the instrument to do this though, as not all phones accelerometer will have had the same tolerances coming out of the shop?
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post #3153 of 4726 Old 04-11-2015, 06:09 PM
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Originally Posted by dominguez1 View Post
I believe you mentioned that your room behaves similarly in that below a certain freq, adjusting phase has little impact on the response?
True, three of the subs have a 0 phase setting and the fourth on is at 180. It is a little odd that one rear is 0 and one 180 but, this gives the most even listening level in the room.
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post #3154 of 4726 Old 04-11-2015, 08:31 PM
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Originally Posted by dominguez1 View Post
@coolrda , can you post the PSD graphs (2x) of just the rear subs inverted vs not inverted?

When inverted, you mentioned that it sucked the SPL out of the room. Did you see that on the omnimic as well?

My point is, that if there was a reduction in SPL, but the PSDs look similar, then PVL must be increasing the sound intensity to produce similar levels.
Heres the graphs.





I pretty much observed the same thing as you did in your video. I'll do some more testing tonight and tomorrow.
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post #3155 of 4726 Old 04-11-2015, 08:51 PM
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Looking at those graphs while reading the DB Forum thread on the same topic leads me to believe that the relationship of SPL and PVL changes at the point where room gain starts. The graph shows the drop in vibration intensity when the rears are inverted. That would also explains why velocity follows the FR then they go their separate way at the long dimension. I want to start testing with all subs straight up with no delay and test that out more. And also work on the main/front sub integration which I haven't dealt with as well as using the miniDSP eq.
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post #3156 of 4726 Old 04-12-2015, 03:05 PM - Thread Starter
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As the image above illustrates, when you had your rear subs in phase, there was more vibration at 30hz. However, when you inverted them, there was a drop in vibration; likely because SPL decreased as a result of the phase shift.

However, at 25hz, you can see that the Vibration increased on the Z axis (blue), but also pretty significantly at the Y axis (red). My hypothesis is that SPL either stayed the same or reduced at 25hz, but the out of phase condition increased PVL and thus Sound Intensity. It didn't behave this way at 30hz because the 1/2 wavelength 'fit' in the room. Whereas at 25hz, the 1/2 wavelength did not; thus reducing the SPL impact that running out of phase would normally have.

@coolrda , do you know what SPL was doing at these frequencies comparatively?
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post #3157 of 4726 Old 04-12-2015, 11:53 PM
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Originally Posted by dominguez1 View Post


As the image above illustrates, when you had your rear subs in phase, there was more vibration at 30hz. However, when you inverted them, there was a drop in vibration; likely because SPL decreased as a result of the phase shift.

However, at 25hz, you can see that the Vibration increased on the Z axis (blue), but also pretty significantly at the Y axis (red). My hypothesis is that SPL either stayed the same or reduced at 25hz, but the out of phase condition increased PVL and thus Sound Intensity. It didn't behave this way at 30hz because the 1/2 wavelength 'fit' in the room. Whereas at 25hz, the 1/2 wavelength did not; thus reducing the SPL impact that running out of phase would normally have.

@coolrda , do you know what SPL was doing at these frequencies comparatively?
Very interesting observation Dom. I think your on to something there. I'll look for the Omnimic graphs. Actually I'll rerun those test and document it better. After reading yours and OKV's comments about increasing PVL, I'm going to explore the out of phase properties and how it all measures out. For instance running all subs without time alignment and then comparing Frequency and Tactile responses without EQing. I didn't get a chance to do any testing today like I had hoped. I'm intrigued by this. If inverting the rear subs not only isn't detrimental to frequencies below the transfer function but actually increases tactile response, my interest is piqued.
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post #3158 of 4726 Old 04-13-2015, 11:14 AM
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Originally Posted by DotJun View Post
Can the vibration app be calibrated somehow, I doubt anyone has the instrument to do this though, as not all phones accelerometer will have had the same tolerances coming out of the shop?
Not that I know of. I have an iPhone 5s, 6, 6+ and several generations of iPads so I was going to try them for comparison. I'm not sure that matters with this type of testing. While that is important in component testing, we are testing tactile/vibrational response of different media/substrate, as well as, how your LF and ULF response coincides with your LF and ULF tactile response. We have a hypothesis that we are trying to prove and one way to go about it is testing and documenting and more testing and documenting. If its repeatable then we may be on to something even if we don't know what that is or understand it right now. Thats why I try to put as much info as possible on these sample. Even if my accelerometer isn't perfectly calibrated ts the same unit used in all my test runs. So any variation that shows up is nullified. Now I may not be able to compare my data numbers with Dom's or anyone else posting theirs, but I bet the patterns will match. So IOW, in said room with front only or front and rear sub arrays or on concrete or riser or suspended floor we will have some idea, some definitive answers of how to tune for a smooth flat frequency AND tactile response, or if thats even possible.
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post #3159 of 4726 Old 04-16-2015, 05:26 PM
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Just a quick update. Took a couple runs on Monday, then spent a great deal of time then and last night trying different phase and eq options. I like how Omnimic Can auto EQ then upload file as REW and implement the biquads into the minidsp. It's easy once you get the hang of it. I think I still prefer Audyssey over the minidsp for EQ. Though I didn't spend much time taking tactile measurements I did take 3 runs each of the subs time aligned and without. As Dom demonstrated at the beginning of this thread there was no real difference in the test runs. They were repeatable and tested the same. You can see ever so slight the advantage to time aligning the subs as far as tactile response of sine waves goes. Tones used were 16-17-18-19-20-25-30-35-40hz.







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post #3160 of 4726 Old 04-16-2015, 08:18 PM
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Dom, time for an update on the next go round. I added two Dayton Ultimax 18 in. sealed subs in 4 ft. cubic boxes and room size 4300 cu ft. The sub will be stacked so, I will have the basically three dual cab subs. These subs will be paired with my 2 vented 18 in. subs and 8 Aura pro shakers. Six Ultimax in sealed boxes and two in vented boxes Thanks!
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post #3161 of 4726 Old 04-17-2015, 08:13 PM
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Originally Posted by derrickdj1 View Post
Dom, time for an update on the next go round. I added two Dayton Ultimax 18 in. sealed subs in 4 ft. cubic boxes and room size 4300 cu ft. The sub will be stacked so, I will have the basically three dual cab subs. These subs will be paired with my 2 vented 18 in. subs and 8 Aura pro shakers. Six Ultimax in sealed boxes and two in vented boxes Thanks!

I would love to come over to your house and watch a IMAX movie of the shuttle launch.


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post #3162 of 4726 Old 04-17-2015, 08:35 PM
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Thanks!
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post #3163 of 4726 Old 04-19-2015, 10:12 AM - Thread Starter
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Originally Posted by coolrda View Post
Just a quick update. Took a couple runs on Monday, then spent a great deal of time then and last night trying different phase and eq options. I like how Omnimic Can auto EQ then upload file as REW and implement the biquads into the minidsp. It's easy once you get the hang of it. I think I still prefer Audyssey over the minidsp for EQ. Though I didn't spend much time taking tactile measurements I did take 3 runs each of the subs time aligned and without. As Dom demonstrated at the beginning of this thread there was no real difference in the test runs. They were repeatable and tested the same. You can see ever so slight the advantage to time aligning the subs as far as tactile response of sine waves goes. Tones used were 16-17-18-19-20-25-30-35-40hz.







@coolrda , this is a great test!

So, at least for sine waves, Time Alignment wasn't that significant of an impact, but nonetheless, it did improve! With complex content, I'm sure TA would have a bigger overall impact than what is showing on the vibration meter...perhaps 'tighter' and more dynamic feeling?

What were your subjective observations for TA vs non-TA? It would also be interesting to see how much difference it would be based upon how 'un-aligned' you are (e.g. how the tactile response varies based on the sub distance in your AVR/EQ relative to the actual physical distance. How much weaker is the impact the further off you are?)
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post #3164 of 4726 Old 04-19-2015, 10:13 AM - Thread Starter
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Originally Posted by derrickdj1 View Post
Dom, time for an update on the next go round. I added two Dayton Ultimax 18 in. sealed subs in 4 ft. cubic boxes and room size 4300 cu ft. The sub will be stacked so, I will have the basically three dual cab subs. These subs will be paired with my 2 vented 18 in. subs and 8 Aura pro shakers. Six Ultimax in sealed boxes and two in vented boxes Thanks!
Nice! You're addicted my friend!

How much did that improve your ULF card? What are you using for power? inuke6k?
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post #3165 of 4726 Old 04-20-2015, 11:49 AM
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These will be stacked and I will use an I Nuke 3000 DSP rated at 3000 watts bridge at 4 ohoms. I already have this amp but, most likely get another 6000 DSP. The DYI subs have been painted and will go into the system tomorrow.

The new score should be 6.6 @ 10 & 12 Hz. I have not figured it for the other frequencies but, I was already at a 5 star rating. The room is also smaller and need to be factored into the score.
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post #3166 of 4726 Old 04-20-2015, 03:33 PM
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@coolrda , this is a great test!

So, at least for sine waves, Time Alignment wasn't that significant of an impact, but nonetheless, it did improve! With complex content, I'm sure TA would have a bigger overall impact than what is showing on the vibration meter...perhaps 'tighter' and more dynamic feeling?

What were your subjective observations for TA vs non-TA? It would also be interesting to see how much difference it would be based upon how 'un-aligned' you are (e.g. how the tactile response varies based on the sub distance in your AVR/EQ relative to the actual physical distance. How much weaker is the impact the further off you are?)
Yes, With multiple subs TA gives you a tighter, quicker and more dynamic tactile feel. Having front and rear sub arrays TA has much less effect though. For instance my front outside subs are set at 0.0ms and fronts inside subs have a delay of 0.58ms. So theres very little difference. Likewise the rear bottom subs are 6.5ms and the top rear subs are 7.5ms delay. So while a minidsp, or like controller, with control over each sub/subs individually is nice its not a big deal. But you must have separate control over front and rear arrays as far as TA goes. Any receiver or preamp with dual sub out should handle this fine. I'll test some more with different distance settings and post.
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post #3167 of 4726 Old 04-20-2015, 07:49 PM - Thread Starter
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Originally Posted by coolrda View Post
But you must have separate control over front and rear arrays as far as TA goes.
Hmmm...I do not. I currently only have the capability to change distance with my AVR (only 1 sub out). I use the distance on the AVR to help smooth the crossover frequencies with my center channel.

I'm guessing my time alignment can certainly be optimized. I have analog EQs (2x eD eQ.2) between the AVR and both front and rear subs, but it only has a phase dial and no distance setting.

Guess I won't be able to TA the front and rears separately without getting a new AVR or minidsp?
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post #3168 of 4726 Old 04-20-2015, 11:28 PM
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Hmmm...I do not. I currently only have the capability to change distance with my AVR (only 1 sub out). I use the distance on the AVR to help smooth the crossover frequencies with my center channel.

I'm guessing my time alignment can certainly be optimized. I have analog EQs (2x eD eQ.2) between the AVR and both front and rear subs, but it only has a phase dial and no distance setting.

Guess I won't be able to TA the front and rears separately without getting a new AVR or minidsp?
My dilemma as well. My almost 8 year old Onkyo preamp is way beyond its expiration date which has necessitated several work arounds. While it decodes all the 7.1 formats it doesn't pass 3D or 4K so I had to buy an external switcher. That was an ordeal as I had to go thru several different models to find one that worked ok. Then I replaced an old BFD with a MiniDSP which I knew about the 0.9V input and output issue when running prosound amps but never thought about it with consumer grade gear. After hearing some chatter the last couple days about the minidsp clipping the inputs on Interstellar I did some additional testing. I never thought that it would be an issue driving the Emotiva amps that I'm using presently due to the EP4000/minidsp incompatibility issues. However the first gen XPA5 needs 1.25v to reach max wattage. I assume the minidsp is a hard cap at .9v which means you would have to throw a voltage meter on the sub outs to make sure you stayed inbounds. If the input doesn't get you by clipping, the outputs will run out before reaching max wattage, sometimes by a substantial amount. Who wants to leave even 1db on the table, let alone 10 or 20. So I loaded up Interstellar and set my Fluke 16 DMM to rec max voltage. Using the clip at the 2:18 mark which seems to be the loudest part of the movie, I made a dozen test runs to see what the voltage output of the Onkyo looked like. On all runs the peak voltage hit was at 2:19:26. I believe this is the high peak in the movie. Its also where my back subs tapped the back plate rather severely right before I was about to tapout myself, while watching with a MV of -8db. This scene is ruthless. My subs are set at -7.5db which is the auto setup setting. So while I knew I couldn't reach max performance with the minidsp in the chain, I needed to know how far I could go, how many DB's was I forfeiting with the minidsp in the loop.

Heres the what the tests revealed.



I was obvious severely clipping the inputs at a MV of -8db. How much am I losing because of the .9v output cap?



This is the volume needed to use the amp to its full potential. A 3db loss is unacceptable. The unbalanced minidsp should be avoided at all costs. If you can't drive an Emotive with its high gain stage, its an unusable product. Maybe a commercial sub would work, I don't know. I'll work around this issue by running the front array straight off the preamp then the rears thru the dsp for the purpose of TAing. that'll help a little while I wait on the DTS:X preamps to come to market. I may even go back to a receiver.
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post #3169 of 4726 Old 04-21-2015, 06:53 PM - Thread Starter
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^^^Nice example.

Agree with unbalanced minidsp...ugh.

Why not just get the balanced? Still pretty cheap at $115. That's why I'll likely do to get the TA right...or just wait to upgrade my AVR. Running an old Onkyo pre/pro 876. Still works great for now...but as you said, DTS:X, Atmos, 4K, etc will push me over the edge in probably late 15' I would think.

Wait...what are the minidsp/EP4000 incompatibility issues?
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post #3170 of 4726 Old 04-23-2015, 10:47 AM
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^^^Nice example.

Agree with unbalanced minidsp...ugh.

Why not just get the balanced? Still pretty cheap at $115. That's why I'll likely do to get the TA right...or just wait to upgrade my AVR. Running an old Onkyo pre/pro 876. Still works great for now...but as you said, DTS:X, Atmos, 4K, etc will push me over the edge in probably late 15' I would think.

Wait...what are the minidsp/EP4000 incompatibility issues?
The minidsp/ep4000 is only regarding having enough output voltage to drive it. They do work ok together. Just a quick update but I may have been premature on my minidsp comments. I measured the output and with the .896v in the output repeatedly was .376v on the outs. That told me the unit was set at the factory for 2.0v. So I opened and move the jumpers. Now input matches output. Didn't really change anything because you just have to lower the gain elsewhere. So my preamp which is capable of putting out over 4v has been cut to the max, from -7.5 with 2v in to -14.5 with .9v in. Its been awhile but I do think I ordered that with the 2v setting to give me some wiggle room. My Onkyo has a separate sub level controls that I can raise if needed that matched the auto level setting, +-15db. My problem is with the efficiency of my speakers the preamp has cut all channels to the max, give or take a db. So I need preamp level attenuation.

I quick word about the Minidsp. The .9v output isn't a hard cap. I measured 1.15v and climbing with the 2v tap being used at around 0dbMV. I don't know what the waveform looks like or the distortion figures but clearly theres some headroom there. I'll run it with one sub only to see what the signal sounds like cranked to that level. The wife has been extremely tolerant of all this insane testing as have the neighbors. Anyway the Minidsp is back on my good side. Though I got sidetracked a little its good to have this info. I'm going over all the data I have and will post what I've found in the next couple days to week or so.
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post #3171 of 4726 Old 04-23-2015, 03:09 PM
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Originally Posted by coolrda View Post
However the first gen XPA5 needs 1.25v to reach max wattage. I assume the minidsp is a hard cap at .9v which means you would have to throw a voltage meter on the sub outs to make sure you stayed inbounds. If the input doesn't get you by clipping, the outputs will run out before reaching max wattage, sometimes by a substantial amount.

I was obvious severely clipping the inputs at a MV of -8db. How much am I losing because of the .9v output cap?
Are you concerned about exceeding the .9v max input on the miniDSP? If so you can just switch it to 2v. I am uncertain whether you are having input or output issues, or if clipping the input is limiting your output. If this is the case, switching the configuration to 2V max RMS input should fix the issue. But I think the output of the mini may also be limited to .9v as well. If that is the issue, not sure what the fix is.

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post #3172 of 4726 Old 04-23-2015, 09:28 PM
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Looky looky what came in the mail yesterday!



I picked up 60 of them for a riser I am planning.

As the pic shows, they are A LOT more pliable then I would have imagined, pretty soft rubber.
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post #3173 of 4726 Old 04-23-2015, 10:05 PM - Thread Starter
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^^^Tuning in..........

Would love to see how you're able to 'tune' the riser by number of these thingamabobs that you use on your riser.

Being able to 'tune' your riser is the question I have yet to see answered...
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post #3174 of 4726 Old 04-23-2015, 10:23 PM
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Originally Posted by dominguez1 View Post
^^^Tuning in..........

Would love to see how you're able to 'tune' the riser by number of these thingamabobs that you use on your riser.

Being able to 'tune' your riser is the question I have yet to see answered...
Will not have the patience for that.... Plus the riser will most likely be about 13' x 10' and filled with insulation. Once it's down, I don't anticipate messing with it much.

That said, I think I read the typical rule of thumb was one every 16" or so. <----I'll probably just stick with that.
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post #3175 of 4726 Old 04-24-2015, 12:41 AM
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Looky looky what came in the mail yesterday!



I picked up 60 of them for a riser I am planning.

At the pic shows, they are A LOT more pliable then I would have imagined, pretty soft rubber.
Excellent. I saw the wheels turning and knew it was only a matter of time. I'm watching
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post #3176 of 4726 Old 04-24-2015, 12:49 AM
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Originally Posted by bear123 View Post
Are you concerned about exceeding the .9v max input on the miniDSP? If so you can just switch it to 2v. I am uncertain whether you are having input or output issues, or if clipping the input is limiting your output. If this is the case, switching the configuration to 2V max RMS input should fix the issue. But I think the output of the mini may also be limited to .9v as well. If that is the issue, not sure what the fix is.
It was answered in the post above yours but I had thought the version I ordered was the .9v but it was in fact the 2.0v so I just moved the jumper. I quickly figured that out when I tested the output voltage. It is rated for .9v max output regardless of input tap used but it will put out considerably more, though distortion/clipping comes into play.

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post #3177 of 4726 Old 04-25-2015, 09:08 AM - Thread Starter
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@coolrda ,

Does your riser have a resonant frequency or tune?

@Luke Kamp ,

I saw you posted that you built your riser, and tuned it to 10hz? Was that on purpose, IOW, did you play around with tuning?

Would love to see any tactile response measurements of your risers if you have them.
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post #3178 of 4726 Old 04-25-2015, 10:14 AM
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Originally Posted by dominguez1 View Post
@coolrda ,

Does your riser have a resonant frequency or tune?

@Luke Kamp ,

I saw you posted that you built your riser, and tuned it to 10hz? Was that on purpose, IOW, did you play around with tuning?

Would love to see any tactile response measurements of your risers if you have them.
I looked around and asked some people and couldn't get a good answer for how to shoot for a specific tune. So I basically thought of it as guitar strings, looser string lower tune, heavy string lower tune. So I built it so I would have the ability to alter it some without a whole lot of effort. I have two boards on top and could easily remove one and I can also add or remove additional 2x3 supports as well. I am using the RDB-220 Neoprene Isolators as feet, but I also have some of the RDB-120's as well that I thought might try changing out.

However I am happy with how it turned out and haven't done any experimenting with altering it. A local member had a buttkicker lfe he was getting rid of and gave me a deal I couldn't refuse and I have come to really enjoy it on the riser. Currently working on finishing up some new front speakers and bought some extra ceiling tiles off Archaea that need installing. Also need to build some stands for speakers once they are done. I use an old phone for calls and texts only and don't have anything to measure tactile response with. I would like to get a new device sometime later this year to get some good data and know exactly where the tune is. Also then if I change out the feet or decide to alter the platform I can more definitely see the changes that are made. I have two young children and a busy summer schedule ahead so not sure when I will get around to this but will post up any results I find.

Keep up the good work of pushing the envelope and keeping the discussion going on all things bass.

Last edited by Luke Kamp; 04-25-2015 at 10:17 AM.
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post #3179 of 4726 Old 04-25-2015, 11:29 AM
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Quote:
Originally Posted by dominguez1 View Post
@coolrda ,

Does your riser have a resonant frequency or tune?

@Luke Kamp ,

I saw you posted that you built your riser, and tuned it to 10hz? Was that on purpose, IOW, did you play around with tuning?

Would love to see any tactile response measurements of your risers if you have them.
While it does, It may not come it play here. By that I mean that even if it resonates it could be so small as to not effect the overall response. Even if it was measurable it would be completely covered up by the fact that your seating's mass is probably a 100x or more compliant. I want a stable riser that feels solid as concrete but has a lighter mass and that what this provides. I believe and I'm finding TR can be changed/tuned somewhat by what you put on and don't put on the Riser. I'll go into more detail later. Remember the point is to decouple/free mass to Intensify tactile response. Whether its 10x, 100x, 1000x or more, this is what should be desired, a stable non intrusive platform that allows the full power of our sub systems to be realized.
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post #3180 of 4726 Old 04-25-2015, 12:51 PM
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Here is a thread on the Auralex product and why you might need to play around with how many are used for best results.

https://www.gearslutz.com/board/phot...ally-work.html

This post by Eric Desart


The problem with the U boats of Auralex is that they give no technical data.
An U boat is an elastic decoupler with a handy U shape to keep it in place.
Auralex gives no technical information whatsoever about dynamic stiffness making it not possible to calculate whatever.

Possible alternatives are CDM, Sylomer, Kinetics stuff and lots if others.

A good floating floor should be around 10 Hz MSM (mass-spring-mass) (lower is better) and not exceed around 16 Hz.

This value for +/- linear springs (the elastic U-boats or any alternative for that matter) is directly related with the deflection of the elastic material under static load.
Hence even without knowing the dynamic stiffness or the physical principles you can test and measure this yourself.

You have a good floating floor if your deflection is around 2 to 3 mm under static load.
Hence ANY elastic material can only be judged within a total construction taking top and floor mass into acount.
The same material can result in a bad or a perfect floor.

You can influence this deflection by in- or decreasing the number of U boats per surface unit, or by in- or decreasing the mass of the top floor.

The relation between MSM and deflection can be rather exact calculated from:

In metric

d = (15.8/fo)^2
fo = 15.8/sqrt(d)
where >>>
d = defection in mm
fo = MSM (mass-spring-mass resonance in Hz)

In Imperial

d = (3.13502/fo)^2
fo = 3.13502/sqrt(d)
where >>>
d = defection in inches
fo = MSM (mass-spring-mass resonance in Hz)

Hence you can easily see that the mass of this top floor, and the spread of the pads or U-boats is very defining.
The basic idea of ANY decoupler is to load them to the maximum technical allowed static load.
Underloading a decoupler will give the false feel of additional safety and more stability, but will cause loss in acoustic decoupling quality which should be avoided if possible.

A rough rule of thumb, in order not to overload such materials is that the deflection should not exceed ca 10% of the initial material thickness. But this can depends a bit on the type of material, the edge factor and so on. E.g. the standard sylomer types will be somewhat less, rubbers can be somewhat more. Best of course is that the supplier provides useful data to work with.
There are 2 main types: compressible decouplers (volume material decreases under load = foam or fibre like stuff) and deformable decouplers (the volume does not decreases or hardly, but the material deforms expanding sideways = rubber like stuff). This latter type doesn't work anymore when you prevent them to expand sideways under load.

Another good rule of thumb is making the top floor as heavy as possible.
That way the relative comparison of temperary loads as e.g. people become less defining.
The more spare (relatively) you have to foresee in order to cover these temperary loads the higher the MSM will become when these loads aren't present + are standard too high (since underloaded) on these spots where such loads aren't present.

I CERTAINLY should put mineral wool (fiberglass or rockwool with low density in that cavity since it does influence STC rather strongly (certainly with a light topfloor). And it also helps to diminish a drumskin effect of such a floor.
If hygro-thermal problems should be involved that's more a matter of the correct use of a good vapour barrier (dampscreen).
A further good improvement is the use of Green Glue which diminishes flanking extremely, makes that floor more dead (drumskin effect) and additionally increases TL somewhat.

About the John Sayers topic I agree with nosebleedaudio.
That topic arose strongly in function of typical drywall separations in a studio setup, where they meant that it has no sense to additionally strengten a link in a chain when the overall TL is defined by the TL of the walls anyhow.

Real high insulations need very low MSMs and can't be obtained with such applications, needing very large deflections. End post

I have been looking around and wonder if these FDS springs may be something worth looking into?

http://www.kineticsnoise.com/hvac/pdf/fds.pdf

Last edited by Luke Kamp; 04-25-2015 at 01:08 PM.
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