2. misc-audio
  3. 161348-121242

Millercarbon's Mega Vibration Control Journey

Vibration control is such a huge, and hugely important, topic it deserves a thread of its own. There was a time I thought it nuts to say such a thing. In fact I wrote a letter to the editor excoriating them for wasting my time on the goofy idea that clamping components between shelves could have any effect on sound at all, let alone be worth spending good money on a rack designed to do just that. This was the Michael Green rack, and thanks to my closed mind and dismissive attitude I never did bother to try and find out for myself if there was anything to it.  

Important Lesson Number One: Don't be so quick to dismiss things just because you can't understand how they could work. 

Couple years later unpacking a McCormack DNA1 amp the Owner's Manual says the included spike can be used to improve sound quality. Well now. As crazy as it still sounded this time its Steve McCormack, and he's already given me the spike, so what do I have to lose? Much to my surprise it did indeed improve the sound. Not a lot. But definitely more detail, clarity.  

This is very early 1990's. There is no internet. I know precisely zero audiophiles. Until stumbling upon this one guy at work who says oh yeah and put your CDP on a phone book, and another one on top. Which sounded even crazier but the guy was serious and this being the 90's we all had phone books laying around so I gave it a shot. This time it was only the most barely perceptible improvement, but it was there. If you really listened for it. So not much. Then again, free. Wrapped some fabric around it, ran the CDP like this for quite some time. 

Around this time I'm shopping for components for my new listening room when this guy is more excited about something called Black Diamond Racing Cones than the amp or whatever he was trying to sell me. So I get 3 of these things and they're so much better than the phone book its hard to believe! Well, okay, it was a phone book. Got to compare against something, right? 

These Cones are so good I take them to this Seattle audiophile club and show them around all excited and.... nobody cares. Except this one guy who goes on and on about how he has tried phone books, tennis balls, racquet balls, styrofoam, cones, spikes, on and on everything under the sun, he's tried it all there's just no way he's gonna be impressed- he makes this very clear to me- but okay you're the new guy let me borrow em why not. But they're not gonna work. No way. 

Next day this guy calls me up gushing going on and on how great these are what are they again where did you find em how many can I get? I actually wind up becoming the Washington State distributor for Black Diamond Racing selling Cones, Shelf, all of it. This guy winds up like me, pretty much everything on BDR.  https://systems.audiogon.com/systems/8367  

A lot of what I knew about vibration control back then was based on my own experience with BDR, and learning from owner DJ Casser. This resulted in what became my guiding principles of vibration control: Mass, Stiffness, and Damping.
128x128millercarbon
mahgister's avatar
mahgister
13,201 posts
 
Bass and high frequencies better accuracy is one thing to go for sure....

But accuracy of timbre instrument is the most difficult to reach....This accuracy is not the results of only some relative balance between frequencies, it needed more work than just my first fine tune set of springs because of some structural properties of my speakers not taken into account by them (internal resonance ? )...


I reach it when i add 2 set of springs boxes on each speakers; one set directly on my multi layered sandwich platform under the speakers, another set of 4 on top of the speakers under the damping and compressing load of concrete on top of my speakers ( 75 pounds)...

Before adding the seconds set of 4 boxes, the accuracy of high and balance between high and bass was good with fine tuning the load....But unbeknownst to me, the timbre accuracy was not optimal...

Then thinking about an idea suggested by rixthetrick,i was thinking about some way to "fine tune the damp mass" of the concrete load relatively to the mass of the speakers, like for some building but it was complicate for me to make exactly that happen...

 Instead i decide to add a second set of springs, on top of the speakers under the damping load; this addition of a second springs set to the first set under the speakers work beautifully because of the difference between them of a compressing force equal to the weight of the speakers...This asymmetry between the compressing force working on the second set of 4 springs boxes give an "elasticity" of reaction to the structure of the speakers, and work marvel....

Astounding difference in timbre perception and imaging....

Why ?

It is perhaps a greater decrease of this ringing effect which  was suggested by  millercarbon or a decrease in the internal standing wave of resonance linked to the structural properties of the speakers.... I am not a scientist and cannot be sure about that...

But the results are astounding.... I consider my mechanical embedding control task now  completed and final with these multi layered sandwiches and double set of springs asymmetrically compressed....

My best to all....
millercarbon's avatar
millercarbon OP
12,531 posts
 
Vibration control is a balancing act. They do this with all musical instruments. Some parts are designed to vibrate a lot, others for stiffness to better control vibrations. Think neck and frets on a guitar. Craftsmen fine tune this with layers of lacquer. It all contributes to the sound. 

Its just for some reason when it comes to our systems we don't think of it this way. But it sure seems to be the case. Things I've been doing lately seem to point in the direction of suspending things freely.  

Everything's a trade off, finding the right balance. Springs alone can leave things free to resonate, and maybe at times too much. My turntable and other stuff sounded great on springs. Until one day there was a deep drone or rumble. It took a lot of chasing down to figure out it was some kind of resonant feedback. The slightest damping of the springs under the turntable would make it go away.  

As John posted above, Max Townshend being an engineer figured out:
The ideal is to have the resonant frequency as low as is possible, ideally around 2Hz in both the horizontal and vertical planes and with a damping ratio of about 0.16. This will give an attenuation of about 25dB at 10 Hz increasing at 20dB per decade above.
This will ensure excellent isolation for the deleterious audio system vibrations which are from 5Hz to 500Hz.
This fits with what happened with my turntable. At least to the extent I'm able to see with my eyes, not having anything to measure this with. But it sure seems to fit with everything I am able to see and hear. 
oldhvymec
5,101 posts
 

millercarbon OP6,501 posts11-09-2020 4:29pmGreat, what I was hoping. So here's my idea: springs between the speakers and the stands. Don't run! Do it like I'm gonna say and they will look almost exactly the way they do now, BUT they will sound a lot better and no more problems with the stands.


<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>

The idea is great, my problem is cutting the pockets. That is apatong wood, (hard) it takes a water cooled bit to cut it.. When I got the legs a mod per leg was, 30.00. I got a hold of the guy to cut the pocket now over 50.00 per pocker 5% accurate. 36 times 50 = 1800.00. There is a one time set up charge of 200, or 250.00. 2100.00 total. LOL the legs were 49-79.00 per set of four...

Shems, inner/outer springs for up and down.. Are the springs your using progressively wound? Tighter at the bottom, than at the top? OR
Same wrap all the way down?

I'll just rebuy and have the mods done and have two set one with and one without.  If I decide to go that way... I can dress the space between the two pieces with a leather seal that will look quite nice, and used often as drawer seals, stops and the like...

I just have think it out.. That is a few quid.. I know the spring aren't that expensive. Getting them in the leg, AND still mounting the leg too. All the mounting holes would be removed by the spring bore. It would take at least 3 screws to secure the leg, or one through the center. More CNC work if I'm not careful..

Suppose I could drag out my duplicating table, for that.. Lot of time... For making gun stocks, guitars body and necks... Cutting weird stuff.. Just need a master to copy from...and add the water cooling pump, hoses, and return tray... I'm an analog guy, what can I say... :-)

Regards
millercarbon's avatar
millercarbon OP
12,531 posts
 
What? Apatong looks exactly like the tight grain reddish brown exotic hardwood in my shop, extremely dense but it is only about as hard as aluminum and can still be cut with router or table saw, you just have to be careful to feed slower. Had mine forever because I hate working with it- one mistake and it takes forever to sand out, if you even can! If you have wood harder than that.... man that's some hard wood! 

Nobsound springs are 1/4" dia and about 1" high. If the speakers are softer on the bottom you could drill 1/4" holes about 1/4" deep and slide the springs in there, however many you need per corner. Only other thing I can think of would be to screw an L-bracket on the side. Wouldn't look quite as good but would only need to stick out 1/4" and you could paint or even cover with a bit of trim. 

Would be nice if you could use springs. They sound better than anything else you could use for this. Or stick furniture felt on the feet and call it good?
oldhvymec
5,101 posts
 
If you have wood harder than that.... man that's some hard wood!

One of the hardest in the world and weathers like Teak.. It is used for wooden decks on wood top low beds and really good steak bed gates.
Wooden legs (when painted) CNC and duplicating sculpture. Yea it will tear up a blade pretty quick, BUT I've used it for years, as trim on baltic Birch. The longer it ages, the more of a chocolate color it turns.. Can't dent it.. Tear a car to pieces with a 1" 24" stick.. Beat it to pieces, LOL

Gotta use water.. It stinks to high heaven too...cut dry.. really stinks...

So the springs are only 1/4" around, that is tiny.. I can bore that with a reamer or a bit...and finish the pocket with flat cutter, shim with 1/4 washers.. That's easy, I was thinking 2-3 inch bore.

Thanks..

Regards
More to discover