|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
216.246.224.202
In Reply to: Re: My symp clone posted by illini_skn on January 24, 2007 at 08:47:16:
I would also like to skip veneer : I feel confident enough to build a big piece of wood that would then be planed, but not to assemble smaller pieces... I have done my share of bad wood assembly and I would like to live it to that.In the light of your much appreciated comments, I finally thought of this :
1/4 inch balsa -- a layer of Deflex rubber -- 1 1/4 inch or so of waxed (rather than varnished) mapple. Without veneer, the layers could be seen, but there is nothing here to hide. All of that on studs.
Follow Ups:
FYI, I'd use foam core or something like gatorboard (which Symposium uses). I think the use of rubber runs opposite to the light & rigid design school that recommends balsa.
All the better then : foamcore is easyer to find and less expansive.I though it might have been too rigid...
The rubber laminated in between the hardwood and the balsa would have been to avoid using vibracones or vibrapods. I suspect that with cones, balsa, foamcore and wood the assembly might lack something soft to pickup the lower frequency vibrations.
There must something I do not understand -- could youplease explain?
Hi remi,I'm standing on the shoulders of giants - many here, Jon, Chris, Ken, Steve, Dave, and others - have done a far better job of explaining resonance control and design than I can.
I encourage you to search the archives.
Generally, there are two schools of thought - heavy mass loading vs. light & rigid. I'd think mixing the two in one device would dilute the effectiveness of either.
As I understand it, the main idea behind the "light & rigid" approach is that all things vibrate; the trick is to not store any vibrational energy. Rubber can be an insulator of certain frequencies, but also a store for them as a heavy, compliant material. Think rubber ball. It's more the high-mass school of thought.
Foam core and like material (gatorboard, styrofoam, corrugated cardboard, etc.) is an insulator too, but because of its extremely low mass for the volume, air space, etc. it is NOT an effective store of vibrational energy. What vibration comes in is immediately dissipated through the material instead of stored or reflected.
This may sound silly and simplistic, and certainly only takes into account specific frequencies, but as a test try tapping on material to get a feel for it. I do that all the time - can't help it!
Tap on a thick piece of foam core. Listen to the sound. Put your hand next to where you tap and feel. Put your hand on the opposite side of where you tap and feel. Vary the pressure of the "feeling hand" (so to speak) to simulate different weight components. Do the same with rubber.
IME (YMMV, etc.), rubber's dead sounding and sucks the life out of music. Light & rigid keeps the pace and energy flowing while effectively isolating from external vibration.
That said, experiment and obey your ears! While general principles apply overall, specific applications vary and what works in one case doesn't in another.
That was longer than I intended when I started. I hope it helps!
I can't avoid bring up the isolation / dampening discussion :I thought of rubber (thin layer, not a block) as a dampenig material, dampenig being, as I see it, a first stage towards isolation. It would have not been close to the component, and part of an heavier isolation device (think of that thick wooden slab I intended to use as a top sheet).
You seem to think light : do you feel there is something "wrong" with the heavy way?
If I decided to go light, I would then go for a thin (1/2in.) hardwood plate laminated to a foam core layer, laminated to a thick balsa slab (1 1/2in.).
But then, taking in consideration that what I use as a rack is not sturdy as should be, should I use vibrapods or vibracones instead of very rigid studs?
Hey, I'm up for discussion - hopefully we'll each learn something.Oh, I agree, rubber does damp. I was unclear. I'm no physicist, but I think the way it does that is to absorb, store, and release vibration. Again, think rubber ball.
I guess most materials work that way.
The heavy mass school says the more mass, the more "sink" for the vibration.
The light & rigid school acknowledges that too and says the less mass, the less storage of vibration. Drop a piece of styrofoam and see what happens.
Both work. Neither is 'right' or 'wrong.' It's up to you in your application to decide what works best for you. For example, George Merrill of Merrill/AR turntable fame, advocated for high-mass 'table stands. Linn likes light & rigid Mana. Both are three-point spring suspended subchassis 'tables.
In my experience, both 'tables sound better on light & rigid platforms. The rigid is particularly important so as not to interact with an already springy suspension.
Then again, Redpoint, Teres, Galibier and non-suspended, high-mass TT designers recommend a giant block of machinist's granite or an active isolation platform like a Vibraplane.
Again, different approach, just as valid and effective. For example, my heavy McCormack DNA amp sounds best to my ears on a DIY Symposium platform - different approach and more akin to mass damped (though it's really constrained-layer) than light & rigid.
In your application, where the rack isn't as sturdy as it should be, I'd think adding yet more compliance via Vibrapods could only make matters worse. The sound would get less focused, less detailed, and muddier. Again, that's just my reasoning - your ears will tell you for sure.
What to do in your situation is a good question. If I were in your shoes, I'd tighten up the rack or no amount of other damping/isolation will work as effectively as it could. Using cables & turnbuckles to cross-brace is a very inexpensive (and light & rigid - ha!) way of doing that. Once that's done, I wouldn't try something heavy to sink the vibration on a lightweight rack - the vibration would have nowhere to go but the shelf. So, I'd again go light & rigid via some sort of DIY Nueance shelf - some balsa/foam/cardboard/veneer concoction.
this makes lots of sense!I have been dealing with new concepts alot during the few days and collected lots of information : I will now let it settle a bit.
*A priori*, I would indeed go for a light and rigid solution, especially, as you mentionned it, because of the flimsy rack and relativly light-weight components (more or less 15lbs).
I will work on this and let you know of the results.
You're welcome and happy to be of service. Let's hope your a posteriori experience validates the reasoning.Please do let us know how you make out, one way or the other.
This post is made possible by the generous support of people like you and our sponsors: