2. tech-talk
  3. 147563-110926

Vibratory or Not?

This is a discussion that for me began on the Stereophile forum which went horribly wrong in my opinion. I was wondering though if this same topic could be discussed here as it comes up a lot in one form or another. My background has been about vibratory tuning as far back as the 70's work in the recording industry and continued into home audio and beyond. The audio signal is one that can be easily tuned, I doubt there is much room there for debate, but we will see, it's Audiogon after all. This being the case I have always concluded that the audio signal is vibratory so has anyone I have ever worked with. It's a common and sometimes even daily practice for someone here to make a vibratory adjustment changing the sound which is obvious to all.

On some of these forum threads however you will see posts saying to get rid of the vibration, without any explanation as to how to remove vibration without altering the audio signal. Every vibratory move I have ever seen done changes the performance of the sound. I've also been a part of the variables of the audio signal during play in real time. If the audio signal is not vibratory how does it change?

I invite you to discuss the vibratory structure and nature of the audio signal.

thanks, lets keep trolling to a minimum please

128x128michaelgreenaudio
michaelgreenaudio's avatar
michaelgreenaudio OP
1,019 posts
 

Hi audionuttoo

"Those who don't experience it will always question and debate it."

First, I'm thrilled to death that you have come up! Second, helping people, especially now, in this industry is paramount in the face of the major changes taking place for listeners. We are at this great moment in the hobby of playback where listeners are moving from very high mass systems to systems that are able to produce so much more music. But listeners need people like yourself to help them make the move to a more practical place.

We went through the age of big robust components and to be honest it was a good time, but now we enter a new chapter. This is the era of the listener and the tools of Tuning. The homework has been done over the past 30 years or so and the demos have been made and continue every day. As you said  "Those who don't experience it will always question and debate it." and that's the bottom line. If someone doesn't have a tunable system they're stuck in the world of talking points.

I hope we see more of you my friend!

Michael

Post removed 
toetapaudio
474 posts
 
Hi Geoff, with regard to your comments on the best pressures for tubes, 15 to 30 psi seems high, we’ve had great results from extremely floppy tubes probably sub 2psi supporting square slate platforms. I was wondering what your thoughts were on this?

Your isolation table design is very interesting but I understand is no longer available? What are you currently using?

Stacore are getting positive customer feedback, are you aware of their designs? I hope to evaluate soon.

Thanks.




geoffkait's avatar
geoffkait
23,365 posts
 
Great question. The ideal internal pressure depends on several factors - the size of the tube or bladder, the number of bladders and the total weight. Design height is the technical term for an airspring height where max isolation is achieved. Design height is a function of air pressure for a given load. However, in terms of sound quality the height and internal pressure can vary. I find a stiffer air tube or bladder or airspring is better than a floppy one. So, the objective is not to have the component “floating on air” as it were but to achieve an optimum mass-on-spring effect, which usually means stiffness is desired. A resonant frequency of 2 to 3 Hz would be a good target. Having said that my guess at inner tube pressure could have been too high, it depends on load. If the load is relatively low then the internal pressure could be low and achieve proper stiffness.

You can measure the Fr by bouncing the component up and down on the air tube and timing the cycles per second. But because there are a lot of variables involved, including how the component is mounted on the air tube, how the air tube itself is mounted, where it’s mounted, etc.

Furthermore, an inner tube is not an ideal geometry. An ideal geometry is low surface area on top and large volume. A long vertical tube would be ideal in terms of geometry but would be very difficult to work with because it would be very floppy. My original Nimbus Platform used a single air spring, which is relatively floppy so the design needed a secondary horizontal sprung system to build up lateral support. The Nimbus airspring was fitted with a large auxiliary air canister to provide a high effective internal volume of the airspring.
geoffkait's avatar
geoffkait
23,365 posts
 
Addendum: one big issue for inner tubes and air bladders in general is that air leaks out through the rubber fabric, just like it does in bicycles. To maintain proper isolation (design height/stiffness) one must pump up the %@&$% inner tube every other day. That’s one reason why I eventually went to mechanical springs.
More to discover