3ll3d00d Posted July 13, 2015 Report Share Posted July 13, 2015 I thought I'd point out some recent posts from avs over here -> http://www.avsforum.com/forum/113-subwoofers-bass-transducers/1488059-your-home-theater-ulf-score-post35732754.html#post35732754 you might need to read the last few pages but basically it is correlating vibsensor output with speclab & adding in fft of the vibsensor data. I realise there is some overlap in the people posting but anyway. Link to comment Share on other sites More sharing options...
Kvalsvoll Posted July 14, 2015 Report Share Posted July 14, 2015 I like what you do with the vibration measurements, and at least one poster has showed good correlation from listening experience to vibration measurements. But keep in mind that this does not measure any sound field properties directly, the measured vibration depends on the mechanical characteristics of the objects that you place the accelerometer on. If you attach the sensoring device to something like a light, rigid cardboard box, and suspend this box such as laying on some loose foam, it is likely that you will get a more correct relation to sound field intensity. From what i see it is still a bit too complicated to expect that someone buying subwoofers should be able to use this to set up the system properly. What we need is something that is easy to use and do not require additional special instrumentation or sensors. Being able to measure with a mic and REW will be a minimum requirement even if one chooses to disregard everything tactile and sound field related, and to get the regular buyer up to this level will be hard enough. Anything that adds further from that in complexity and difficulty will be unrealistic. If simple rules to avoid the bad scenarios can be found, that could be a solution. We already know that subwoofers at both ends of the room is problematic. But then this is the solution to get rid of all nulls if you don't absorb the reflection, so placing all subwoofers up front won't work in all rooms. Link to comment Share on other sites More sharing options...
3ll3d00d Posted July 14, 2015 Report Share Posted July 14, 2015 But keep in mind that this does not measure any sound field properties directly, the measured vibration depends on the mechanical characteristics of the objects that you place the accelerometer on. If you attach the sensoring device to something like a light, rigid cardboard box, and suspend this box such as laying on some loose foam, it is likely that you will get a more correct relation to sound field intensity. is this to try to decouple the device from what it is sitting on/attached to and hence gets closers to measuring the effect of sound alone? From what i see it is still a bit too complicated to expect that someone buying subwoofers should be able to use this to set up the system properly. What we need is something that is easy to use and do not require additional special instrumentation or sensors. Being able to measure with a mic and REW will be a minimum requirement even if one chooses to disregard everything tactile and sound field related, and to get the regular buyer up to this level will be hard enough. Anything that adds further from that in complexity and difficulty will be unrealistic. it's certainly not a particularly user friendly approach that's for sure. The population using mics has certainly increased over the last 10 yrs but it's still not that common to see people using something other than an auto setup routine. Link to comment Share on other sites More sharing options...
Kvalsvoll Posted July 14, 2015 Report Share Posted July 14, 2015 is this to try to decouple the device from what it is sitting on/attached to and hence gets closers to measuring the effect of sound alone? it's certainly not a particularly user friendly approach that's for sure. The population using mics has certainly increased over the last 10 yrs but it's still not that common to see people using something other than an auto setup routine. Yes, decouple to try to get a more even response of the vibration measurement. But as long as you know the issues and limitations of the measurement method, it can still be used to see differences, as @coolrda showed. This is for those interested in finding out more on what is going on, learn more and experiment, because we find it interesting and it is our hobby. And as more people get involved, there will be more experience and cases to study, which will lead to a better understanding and eventually some rules for set-up. Link to comment Share on other sites More sharing options...
coolrda Posted August 13, 2015 Report Share Posted August 13, 2015 Gimme some VSensor data. Link to comment Share on other sites More sharing options...
Kvalsvoll Posted August 15, 2015 Report Share Posted August 15, 2015 @coolrda, I sent you a message with the velocity sensor info some days ago, I hope you saw it. Link to comment Share on other sites More sharing options...
coolrda Posted August 17, 2015 Report Share Posted August 17, 2015 I did get that and appreciate it. I've taken a break from the testing for a month to get some much need thing accomplished so will look into this further at then. Thanks very much for this. Link to comment Share on other sites More sharing options...
3ll3d00d Posted May 31, 2016 Report Share Posted May 31, 2016 I thought I'd cross post http://www.avsforum.com/forum/113-subwoofers-bass-transducers/2118090-vibsensor-accelerometer-test-thread-post44404929.html#post44404929over here in case anyone is interested using an wide bandwidth accelerometer (and an appropriate preamp) to measure TR at the seat and capturing that using speclab, this shows the relationship between the motion of the seat and the input signal much much more clearly than vibsensor which is quite handy. My accelerometer preamp has been calibrated but my signal chain was not calibrated in this chart (so that I can translate a dBFS figure in speclab to a physical quantity). Link to comment Share on other sites More sharing options...
dgage Posted June 1, 2016 Report Share Posted June 1, 2016 Love it. Thanks for sharing. What accelerometer and preamp are you using and where did you get it calibrated? I'd be interested in this for some of my own testing with different platforms but I'd also like something for measuring cabinet panel resonance/vibration. Are you familiar with anything for measuring cabinet panel vibration? Thanks. EDIT - See you mentioned the equipment in this post - http://www.avsforum.com/forum/113-subwoofers-bass-transducers/2118090-vibsensor-accelerometer-test-thread-20.html#post44405793. Still wondering about an accelerometer for measuring panel vibrations if you have any ideas. Link to comment Share on other sites More sharing options...
3ll3d00d Posted June 1, 2016 Report Share Posted June 1, 2016 Love it. Thanks for sharing. What accelerometer and preamp are you using and where did you get it calibrated? I'd be interested in this for some of my own testing with different platforms but I'd also like something for measuring cabinet panel resonance/vibration. Are you familiar with anything for measuring cabinet panel vibration? Thanks. EDIT - See you mentioned the equipment in this post - http://www.avsforum.com/forum/113-subwoofers-bass-transducers/2118090-vibsensor-accelerometer-test-thread-20.html#post44405793. Still wondering about an accelerometer for measuring panel vibrations if you have any ideas. I bought this for precisely that purpose. The EoT thing is just an interesting diversion and I figured measuring excursion might be interesting too. It is the same accelerometer as in http://www.libinst.com/accel.htm and there are some threads on diya too. Link to comment Share on other sites More sharing options...
dgage Posted June 1, 2016 Report Share Posted June 1, 2016 How do you plan to solidly attach it to a speaker or sub panel? Link to comment Share on other sites More sharing options...
3ll3d00d Posted June 1, 2016 Report Share Posted June 1, 2016 How do you plan to solidly attach it to a speaker or sub panel? fixing wax, e.g. https://www.amazon.co.uk/gp/product/B00DSYPM76/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 see p15 of http://www.bksv.co.uk/doc/br0094.pdffor an example of the effect of wax apparently you can use double sided tape as well, see http://www.meas-spec.com.cn/downloads/Using_Double-Sided_Tape_for_Accelerometer_Mounting.pdffor some detail I'm thinking of taking measurements at a series of points (in a grid layout) on each panel. I have 2 cabinets that are built in the same way to compare, one is braced and undamped while the other is damped (with http://www.silentcoat.co.uk/products/silent-coat-extra-4mm-mat-door-pack)but not braced (at present). Link to comment Share on other sites More sharing options...
SME Posted June 1, 2016 Report Share Posted June 1, 2016 Can you do a sweep with REW and the accelerometer + pre-amp as the input to get the tactile response? Link to comment Share on other sites More sharing options...
3ll3d00d Posted June 1, 2016 Report Share Posted June 1, 2016 Can you do a sweep with REW and the accelerometer + pre-amp as the input to get the tactile response?Yes Link to comment Share on other sites More sharing options...
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