Mijosty,
Long winded is my middle name. Anyone who ever spent time on the phone or has met me in person knows this. As not to bicker or argue over points of resonant frequency and amplitudes of resonance continuously forming on “all” vibrating surfaces and hopefully putting us on the same page of understanding, I urge you to review this document.
http://www.starsoundtechnologies.com/CMS/uploads/vibration-and-coulomb-friction-2013_001.pdf
Regards to renderings on testing:
My point was that ‘live environment’ testing results are meaningful only to the designer. I was hoping to pick up more on the studies of driver function, formation from shear waves to compression waves, velocity of various materials and anechoic wave patterns but that would require another half-dozen paragraphs. ⌣
We can perform the same accelerometer testing on your system in our lab that would clearly differ in comparison to your results unless we have the same room sonic environment, the same equipment support systems holding the model, the same racking system holding the test equipment, the same attachments and stand for supporting the calibrated microphone or accelerometer or recording drives and the list goes on. The measurements would greatly differ.
Regards to resonant frequency:
Any resonant frequency can be changed easily. Based on your postings, my guess is your physical model is not providing you the best information due to the cheap spikes and environmental obstructions limiting the performance of your subwoofer.
Changing the resonant point of your test model, say we replace the cheap spikes and put the enclosure on $300 Audio Points or a $500 Platform. The changes in sound quality would improve as would your testing results where you would realize how much further along you are in the process of development.
Now place the same model on a $1200 platform and you will also notice how much more effective your design is in sonic as well as the differences in measurement. To prove beyond any doubt that you are ahead of expectations, place the same model on a $2,500 platform and that might show you where your inefficiencies are in the design along with advancing the test criterion and more importantly, really focus on the sonic improvements.
By changing the effectiveness of the grounding plane (platform or spikes), the transfer of resonance becomes reality where your book-mentored approach might change as well.
*A subwoofer measurably generates less distortion when it is firmly spiked to the floor. I do not know if this is true for a full range loudspeaker that is crossed to a sub at say 100 Hz.
This is true regardless of speaker size, mass, material science, construction, or crossover points. If you use a higher end spike, there will be much less distortion to begin with.
*Does vibration transferred to a purely electronic device cause audible distortion?
It would take a massive series of vibrations or a poorly designed chassis with a cheap footer system where I do not believe any of those exist in today's marketplace however, any device using manmade power will vibrate. Vibrations (mechanical, electromechanical or airborne) establish resonance and clogging of the signal pathways establishing component operational inefficiency. When the inefficiencies are mechanically grounded and transformed into component operational efficiency, one will hear the difference regardless of tube or transistor design.
*Designing a decent speaker spike is child's play as is making a decent speaker stand. Locking the speaker to the stand is also child's play as long as you don't mind sinking a few screws into the enclosure. Designing and making a subwoofer enclosure that does not shake or resonate is not so easy. Do you have any siggestions?
Yes a few… but first,
My experience with subwoofer driver and cabinet development was spent with the engineering team at McCauley Sound and working in the sound reinforcement business with three highly successful sound companies. I was part of a four person team that designed and manufactured over 300 custom subwoofer enclosures in the days of IASCA Tournaments and have participated in the build of a few championship vehicle systems that toured audio and electronics shows.
We just placed a pair of twin modified 18” subwoofers into our mechanically grounded Energy Room in Madison, WI to see how much pressure level is required in an attempt to acoustically overload the walls, floor and ceiling. Imagine having the feel and dynamic headroom of a live event in a studio setting? Yet the room is capable of hearing every note and decay defining the difference in sound between two different brand names of woodwind or string musical instruments.
http://www.mccauleysound.com/product_overview.cfm?ID=2338
https://systems.audiogon.com/systems/8168
I just wanted you to know, we do have some experience in your field of interest.
According to you, developing a "decent" cone is childsplay. Really?
We have witnessed a multitude of “decent” vibration management companies come and go over the years, but few remain past the ten-year mark and by the twenty-fifth year, all of them are no longer in business with exception to maybe two companies.
Your "decent" speaker stand design that was also defined as child’s play might climb to the level of a boat anchor by our standards.
If the speaker resides on our products using a few screws to attach the speaker to the stand will alter its original sonic - guaranteed.
The point being "decent" does not survive High-End Audio.
Suggestions:
1 There are talented designers that have already surpassed your level of achievement so I would always recommend reaching out to them or gathering information on their products adding to your understanding and level of research.
2 Get the subwoofer off carpeted surfaces and cheap spikes. Hard surfaces will define all that is going on without the absorption of rubber/foam carpet. Place the sub on a neutral grounding plane. Contact some manufacturers to see if they would accommodate you with pricing in order to attain a quality grounding plane for your testing.
3 Concentrate on the sound and forget about the hand touching tests or physically stomping on flooring tests that are totally irrelevant to speaker design and sonic performance. Do not forget as you are adding mass, the product has to be capable of transport and positioning.
Good luck with your future in designing and we hope it earns you a living or a place in the industry or self-gratification if that is what you seek.
Please feel free to phone us, we will always be happy to answer questions or assist in solving anyone’s audio related issues or just talk sound.
Thank you for your time,
Robert
Star Sound
