Speaker Placement, Stanks, Tweaks and Tuning for Better Sound

 

Gold Member
Username: Dakulis

Spokane, Washington United States

Post Number: 1231
Registered: May-05
Hey guys,

Given the fact that many of you shared advice on how to place speakers in a room and some other tweaks that one might try, I decided to put that material here so someone can refer to it in the future and we can collect additional information since many of the things suggested I would never have thought of on my own. So, here's the stuff and feel free to add.

From Jan: "Look at what works as a good equipment stand and notice how the shelves are decoupled from the open shelved unit; http://www.tnt-audio.com/clinica/flexye.html "

"Trying just one isolation footer or just one AC conditioner is like trying just one glass of wine and deciding whether you like wine or not. . . Accessories are often a "suck it and see what comes out" sort of upgrade. The isolation device which works for a turntable probably isn't the isolation device that will work equally well for a power amplifier. Most importantly, what you expect from the accessory matters immensely. While it's true that accessories can make as much or more of an improvement in a system's performance as would upgrading to more expensive gear, most people are expecting that same change in sound quality to be immediately evident when they use an isolation foot. Probably not going to happen. Accessories are more often a cumulative system of subtle but important upgrades which, when taken as a whole, perform the task of improving the transparency and fidelity of your music. It's not uncommon for the performance of an AC conditioner not to become apparent until you've also provided better isolation for the components or better speaker placement for the system. One adds to the other in a synergistic manner."

"Second, much of "how" I go about deciding what to change in accessories comes from curiosity and experimentation. I don't recommend anyone on this forum, given the level of equipment we all have to work with, should spend $1k on isolation feet. While there are exotic materials and precision construction methods employed which are unobtainable outside of the specifcs of some $1k footers, most accessories begin as someone thinking about something and finding a solution that works for them. So a sandbox or inner tube isolation box is not outside the capability of most diy'ers. Filling a large baggie with sand or lead shot or buying a few diving weights is not all that difficult for an experiment. Trying halved racquetballs under your equipment is certainly not impossible even for someone who doesn't know which end of a hammer to hold. Neither is the simple Jenga block under a component. However, you have to have the idea either from your own head or the ability to figure out what the other fella has done that you can copy for less money. Each of the above "tweaks" will result in a different sound when used with different gear. And, to begin with, even the best accessories cannot overcome the problems of basic equipment placement in a good rack or stand and really good speaker placement."

SOME SPEAKER PLACEMENT THOUGHTS:

http://www.decware.com/paper14.htm

http://www.tnt-
audio.com/casse/waspe.html


http://www.cardas.com/content.php?area=insights&content_id=26&pagestring=Room+Se tup

INEXPENSIVE STANDS

http://www.head-fi.org/forum/thread/179442/the-ikea-lack-rack-thread

SOME OF JAN'S HANDY DANDY TWEAKS

http://www.homedepot.com/h_d1/N-5yc1v/R-202310703/h_d2/ProductDisplay?langId=-1& storeId=10051&catalogId=10053

I use VPI "magic bricks";

http://cgi.ebay.com/VPI-dB-5-MAGIC-BRICK-BLOCK-DAMPEN-TRANSFORMER-AMP-NOISE-/290529013575

The Shakti Stone is the modern day VPI brick;

http://www.6moons.com/industryfeatures/edge1/edge1.html

This is what I use under my (Rega Apollo) CD player;

http://vibrapod.com/

These too are sitting on a three layered MDF constrained layer block which was actually the plinth to an old Well Tempered turntable;

http://www.welltemperedlab.com/frameset2.html

You can diy this very easily with the slabs of 3/4" MDF bonded together with GE silicone caulk (you'll need a few clamps to make this work) or just use the thinnest rubber shelf liner which will act as a secure gripping agent/damping material between layers. Woodworkers use this same material to secure their router pieces to the table so once you set something on this material it will stay in place yet provide effective damping between layers. The CD player and pre amp sit in a stand that acts as a suspension system for each shelf.

My turntable is sitting on something similar to the 10" thick AB butcher's block shown here;

http://chefdepot.net/butcherblock.htm

From Chris: http://shop.mapleshadestore.com/Isoblocks/products/1/

From Jan again: Another Ikea project;

http://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/211672-diy-ul tratouch-cotton-bass-traps-broadband-absorbers.html

"Bass traps or some sort of acoustic treatments are almost always useful in a domestic environment where the intended purpose was not necessarilly to provide good sound. There are multiple points of contention regarding room treatments, two of those points that few would dispute are, first, that using conventional traps will result in broadband absorption of frequencies rather than targeted response in a specific bandwidth. The second is that conventional traps will need to be rather large to be effective at the low frequencies which are problematic in most domestic locations. While anything placed in the corners and first reflection points will likely be better than nothing, a bean bag by itself probably isn't going to be worth the space used when other, more effective methods could be employed for greater benefit. You can buy ready made and preformed insulation rounds or squares meant for going around HVAC ductwork which will be very effective when set up properly. There are plans for the construction of such devices on the web."

An ASC "Tube Trap";

http://www.asc-hifi.com/tube-trap.htm
(Fiberglass is hazardous and should be treated with some degree of respect. Read about handling and using fiberglass before you commit to any diy project where it will be used.)


Once in place, the traps can be rotated to provide a tuning of high frequency reflection to bass absorption, in other words, the long waves of the bass signal will pass through the trap and be absorbed while the shorter waves of the upper frequencies will be reflected back into the room to provide a desired amount of "air" to the final product. The traps are open tubes - hence the name - which might have an internal layer of additional fiberglass suspended in the center. As the pressure wave passes through the multiple layers of material, it is the transition from low pressure to high pressure which acts as the "absorption" device. The wavefront strikes the absorptive materials and is converted into heat and taken down in level in the same manner fiberglass insulates against heating or cooling loss in your attic or walls. By placing absorptive materials slightly away from the wall the trap can be made more effective by using the reflection off the wall to redirect the wavefront back through the trap for one more passthrough. Obviously a thirty foot wavefront doesn't care if the trap is two inches away from the wall so experimentation in placement is suggested.

Different materials will have different coefficients of absorption but also higher degrees of difficulty in sourcing and working with, say, fiberglass rolls vs rigid fiberglass panels. The two rules still apply, to be effective at very low frequencies, the traps must have some thickness and, even with the reflective material added, traps are mostly broadband absorption and will begin to take away some of the life in the music if used in excess. Due to the latter effect most people get excited about the benefits of room treatment once they've heard the benefits of a few corner traps and then tend to go overboard at first only later pulling back by taking out the excessive amount of absorption. This means there are always a good number of used traps on the market at decent prices."

After the corners of a room, the next point of treatment that any speaker/room interface will probably require and benefit from would be treating first reflections. Once again the ways to go about this are up to you and in reality most rooms will benefit more from diffusion at this location than absorption but you decide which is more appropriate for your set up. You can easily make up a quickie diffusion panel from a large piece of cardboard scored halfway through at irregular intervals and bent to make a series of "WWWWW" cavities.

To the extent possible in your situation, traps and diffusers should be of equal value on both sides of the room to maintain symmetry in the absorption/reflection/diffusion (the three ways to "treat" a room) of each channel. When thinking of treatments, it is almost always the amount of surface area the wavefront encounters that makes the difference. Therefore, if you're thinking about placing a hanging blanket behind your listening position to knock down a bit of a reflection, giving the material a few loose pleats will increase the surface area and therefore increase the effectiveness of your plan. (Diffusion rather than absorption is once again likely to be the superior treatment in the rear of the room.) The same rule applies to all other types of treatments; maximum surface area and moving the wavefront from low pressure to high pressure multiple times are the keys to good absorptive/diffusion treatments. If you're using diffusion systems, they should be somewhat irregular in their pattern in order to have their highest benefits."

"One more possible diy isolation device is a sort of roller ball arrangement. It's difficult to find cupped metal saucers and what you might find will typically lack the dimpled surface of the real rollerball devices but you can usually find wooden cups which are intended to be placed under the legs of furniture and meant to take away the marks of the leg in a carpet. These make satisfactory bases for any number of balls of various sorts. You'll usually want three balls in each cup and the materials can either be conventional steel bearings or you might want to try a few of the wooden balls found in crafts stores. A fairly transparent system will indicate which materials provide the best interface between bearings and equipment. You can easily look at any of the commercial products to figure out how to construct these diy rollerballs. Some diy'ers will add a second cup on top of the bearings to provide a flat surface against the equipment or shelf. The essential idea here is a ball will only contact another surface at its tangent (high mass resting on a small point, same idea as a spike or cone) thereby providing good isolation from any vibration - acoustic or mechanical - which might be coming upwards from the supporting shelf. By placing three balls against one another in the cup, you should also have a good drain device for internal vibrations which would be inherent within the equipment from something like a power transformer. Once again the idea is always to couple and to decouple at the same time. As far as numbers go, three will almost always be a better number than four when dealing with support devices. Three points can define a plane and will be largely self leveling while four points can wobble if the supporting surface is not perfectly level. In electronics - not turntables (turntables require entirely different isolation techniques), always begin with one foot under the power transformer and add the other two to make the component stable. Bypass the existing rubber feet on the equipment with isolation or coupling devices."

If you haven't visited this page on the ACS (TubeTrap) site, do some reading to educate yourself to the theories and application of room treatment devices;

http://www.asc-hifi.com/articles.htm

"This broader concept of how sound travels within a confined space is the thinking behind the more traditional "LEDE" or "live end, dead end" room treatment system"

http://www.jdbsound.com/art/art517.html

"I would suggest anyone starting out with room treatments also do some reading about this theory of room set up by simply placing something akin to "LEDE room treatment" in a search engine."

Okay, I have to get back to work but I want to thank Mr. Vigne for most of the information above and Chris and Stu for their additional input. By all means add your knowledge to it as the above has made a tremendous difference in the sound of my system. Dave
 

Gold Member
Username: Dakulis

Spokane, Washington United States

Post Number: 1232
Registered: May-05
That should be "Stands" not "Stanks", LOL
 

Gold Member
Username: Hawkbilly

Nova Scotia Canada

Post Number: 1296
Registered: Jul-07
Thanks for pulling that together Dave. I just received in the mail yesterday a new "tweak" to try. I purchased two set of the Terrastone footers for my cdp and integrated amp.

http://www.vermontaudio.com/photogallery.html

I tried them out last night. They are the first consequential adjustment of this type that I've made in a long time. I've tried at least a dozen different DIY or purchased products in different configurations to see their impact on the sound of my system, sometimes with a little improvement and sometimes not. These though made quite a difference, most notably in focus and tranparency. Dan, from Edensound provided me a couple of different options for bearings, and I've found the Torlon bearings work best.

The only negative is that these things have very little traction (very smooth and slippery) under the amp, so if you just reach to turn the amp on as normal it will move a bit. You have to secure the amp with one hand and hit the power switch with the other. Keep in mind my amp is pretty small and quite light, (relatively speaking). I could see a problem if you had a fairly light amp and heavy cables pulling on the back. The thing might slide off. Not a worry for me as I use very light cables. If it was a big worry, a change of bearings would largely resolve the issue.....go with wood, ceramic or brass perhaps....though there would be a slight impact on the sound.....for better or worse.

They are pricier than the Isonodes,Vibrapods, and brass footers (Parts Express) I have, and definitely more expensive than some of the DIY stuff I've tried, but deservedly so in my opinion. I'll report back again once I have more time to listen with them in, and confirm my initial impressions. Right now I have them on bamboo cutting boards which are sitting on Isonodes....which all sit on my Flexyrack. I might try removing the cutting boards and just sit the Terrastones directly on the rack shelf.....just to hear the difference.
 

Gold Member
Username: Dakulis

Spokane, Washington United States

Post Number: 1233
Registered: May-05
Chris,

As soon as I get the "furniture" sold and the rack in place and everything set-up, I'd like to hear more about these guys and their products.
Dave
 

Gold Member
Username: Kbear

Canada

Post Number: 1015
Registered: Dec-06
Chris, I've had my eye on a couple of edensound products as well - the Terrastones and also their damping plates. I definitely intend to try them out, especially if your lasting impression is positive.
 

Gold Member
Username: Hawkbilly

Nova Scotia Canada

Post Number: 1297
Registered: Jul-07
I'll keep you posted. I'll get more of an opportunity on the weekend to get more time with them in and out of the mix.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16073
Registered: May-04
.

Dak, I am honored to play a small part in a thread which finally addresses the highy controversial topic of "stanks".





























.
 

Gold Member
Username: Stu_pitt

Stamford, Connecticut USA

Post Number: 4389
Registered: May-05
Stanks are nice, but I much prefer skanks personally.
 

Gold Member
Username: Magfan

USA

Post Number: 2253
Registered: Oct-07
I always thought that was how you killed a vampire....
Drive a stank thru its heart?
 

Gold Member
Username: Dakulis

Spokane, Washington United States

Post Number: 1235
Registered: May-05
Geez guys,

I proofread the entire post and miss the title, what a loser!!! LOL

Jan, if not you, who? If not now, when?
 

Gold Member
Username: Stu_pitt

Stamford, Connecticut USA

Post Number: 4390
Registered: May-05
I'll add two methods of speaker placement that I really like -

Sumiko's Master Set procedure
Audio Physic's Speaker Placement

I'm on my iPhone and it's a PITA to copy and paste, otherwise I'd post links. A Google search brings them up nicely.

I've used both and think they're equally effective. A little different sounding, so maybe I messed up a little bit. I preferred Audio Physic's method with my Audio Physic monitors (surprising, huh?), and the Master Set with my PSB towers when I had them. The differences could also be more pronounced with different rooms and speakers.

I have to play around with placement in my current space, but I'm a bit short on time. They're placed pretty well, but I know I could benefit from fine tuning a bit.

For anyone on the fence about Jim Smith's "Get Better Sound" book, grab a copy. I don't think there's anything revolutionary in it, but it gives a great perspective of what you should realistically look for in a system, and gives some great tips on fine tuning. Definitely worth the money and the time to read it.
 

Gold Member
Username: Dakulis

Spokane, Washington United States

Post Number: 1241
Registered: May-05
Stu,

Great info and book title. I wish you had posted it before I left on vacation, I would have bought and brought it for a read. Oh well.

I did get rid of the large piece of furniture in the room before I left. My wife relented and allowed me to put in the new VTI stand. I went up towards the top of VTI's product line so I found the quality to be fair for the price and better than I expected. I think the stand legs will need sand or something to help deaden the vibrations.

The mdf is thin and could just some additional isolation, it came with a four pieces of isolation tape, about 3/4" on each level and I added four more pieces of about the same length on each level. But, we're still not talking enough isolation and I can hear just a slight vibration on the CDP level.

However, the biggest thing I noticed is a very real change in the sound in the room without the large cabinet. The room sounds like it's more alive but not in a good way. There's a little more of the "jazz stage" AVR type effect where the room sounds like there's a bit of echo or reverberation. So, I'm sure I may have to play around with the speaker set-up and placement again and I'll start trying some of the tweaks and isolation devices that Jan recommended.
Dave
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16077
Registered: May-04
.

Buy an inexpensive stethoscope at the drugstore. It will help tremendously when you're trying to assess the benefits of isolation and damping techniques. Obviously, you must begin with a baseline from which you move forward. So take a listen to each component of the stand and the equipment before you change anything and, as always, only change one thing at any time.

If the shelves provided by the stand manufacturer are too thin and resonant, it would be best to change them out for a more appropriate material. I'm assuming the shelves rest on some sort of brace which has the "isolation tape" affixed to it. Try some BluTak, PlastiTak or Mortite and place a small glob on the brace then sink a medium sized ball bearing into the soft material. The shelf should then rest on the bearing and not on the squishy material.


.
 

Gold Member
Username: Stu_pitt

Stamford, Connecticut USA

Post Number: 4391
Registered: May-05
What exactly are you doing with the stethoscope, Jan?
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16078
Registered: May-04
.

Listening. The stethescope can help you when you're trying to locate the point of highest and lowest resonance. It can also tell you how effective your fixes actually are rather than relying on what you think you've accomplished. Most of us assume what we do is good no matter what result we achieve. Listening through the stethescope will tell you what you've actually improved or not improved. If you're applying damping compound, you want to place it where it will have the most effect. Possibly all you've accomplished is to split the resonating surface into two areas rather than one. Don't guess, find out. Placing isolation devices should be a simpler affair if you can actually hear when the resonance has been brought down to its lowest level. Twenty to thirty dollars should get you a more than adequate device.


.
 

Gold Member
Username: Magfan

USA

Post Number: 2262
Registered: Oct-07
Radio Shack will sell you an accelerometer so you can quantify your result.
http://www.radioshack.com/product/index.jsp?productId=2909788
Not exactly 'plug and play', but for the more advanced DIY guy, may yield a result.

Because of how it works, I'm not sure of the frequency response.

Other sensors work on the piezoelectric principle and may be easier to interface.....
 

Gold Member
Username: Dakulis

Spokane, Washington United States

Post Number: 1242
Registered: May-05
Leo,

I wouldn't know a "piexoelectric principle" from a "vice-principal" but I'm sure it's very important.
 

Gold Member
Username: Magfan

USA

Post Number: 2263
Registered: Oct-07
Sorry, Dak, I can get a little techie at times.

Piezo is simple. Remember 'ceramic' cartridges on inexpensive TTs? It had a quartz crystal inside. Mechanically vibrate it and you get electricity. Feed it electricity and it'll vibrate.
Precision timekeeping makes good use of precisely made crystals and it it a boon for tweakers. Many hi-fi tweaks depend on this 'effect' including the patented Shakti stones......

Some accelerometers work on the same principle. A piece of quartz is attached to the piece under test and you feed the electricity produced to a laptop with the appropriate software. That's how Stereophile tests for cabinet resonance during speaker tests...

It is pretty simple and straightforward, if not a little OCDish, for the DIY guy with a home made rack........

The stethoscope with doubtless work for big changes. running a sweep frequency from the stereo (got your test CD ready?) will allow you to judge frequency and subjectively the amplitude, as well. But for the true overachiever, 'ya can't beat a real accelerometer and software!
 

Gold Member
Username: Dakulis

Spokane, Washington United States

Post Number: 1243
Registered: May-05
Leo,

I'm glad that's just a little techie. I'd hate to see you in full out techie mode. LOL

Dave
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16088
Registered: May-04
.

Leo, got any ideas where I can find plans for a DIY nuclear power plant? The ol' gas powered generator just seems so low tech nowdays.







.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16089
Registered: May-04
.

Dak, here's another DIY for finding the highest/lowest resonant points though it doesn't do so well on vertical surfaces. A glass half filled with water and placed on a shelf or any flat horizontal surface will do nicely when you are trying to find the correct spot for damping. Obviously, water and electronics don't mix well so this is a limited location idea. But, if you're trying to find out whether a tweak has made any difference in the vibration of a shelf or, say, a turntable platter, this is a cheap place to begin.


.
 

Gold Member
Username: Dakulis

Spokane, Washington United States

Post Number: 1248
Registered: May-05
Jan,

I've got the new set-up in place now. I should probably takes some pics and post them. You'll like it alot better. I've done a little more damping but didn't have a stethoscope so maybe I'll try the water glass half full. That's right, I'm an optimist. LOL and thanks, Dave
 

Gold Member
Username: Magfan

USA

Post Number: 2276
Registered: Oct-07
Back at 'ya, Jan.
Your wish is my command::

http://pesn.com/2011/01/17/9501746_Focardi-Rossi_10_kW_cold_fusion_prepping_for_ market/

A way to do the vibration thing without water is to use a mirror and a laser pointer. Hold real still.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16093
Registered: May-04
.

Italians and a cold fusion reactor, eh?


Yea!!!


What could go wrong?

The only problem I see is, everyone knows those guys in Bologna are f'ing nuts.


I love the web page though, particularly the section on "Hydroxy". I used to dunk those in milk when I was a kid.



.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16094
Registered: May-04
.

"A way to do the vibration thing without water is to use a mirror and a laser pointer. Hold real still."


OK, but do you put the laser pointer or the mirror in the glass?



.
 

Gold Member
Username: Magfan

USA

Post Number: 2277
Registered: Oct-07
Knew you'd love the cold fusion. Fleishman and Pons? The university where they worked has let the patent lapse.

This is as close to a DIY reactor as you will see for a while.

I'd put the mirror on the surface and bounce the laser pointer off it. It should act as a lever/fulcrum and 'magnify' the movement. Max movement at resonance, of course. I have a 6" optically flat front surface mirror in the form of a Silicon Wafer. A back surface mirror may have enough diffraction to matter. Using this mirror, I can reflect the sun to a surface 100 feet away and it is still about a 10" circle. That's pretty flat.

However, please note that in my original post, I mentioned the word 'overachiever'.
http://www.wavefrontlabs.com/Wavefront_Labs/Accelerometer_Data.html
I have no idea of sensitivity OR cost, but this is for an IPhone, for Pete's sake. The hi pass / lo pass filter options increase usefulness. If I still had a fast car.......

For someone with both a LOT invested in a system and great curiousity, this option may work. From Omega, it ain't cheap, but may do the job.
http://www.omega.com/ppt/pptsc.asp?ref=HHVB82&Nav=prek02
I'm not 700$ worth of curious, though. Less expensive options are out there.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16095
Registered: May-04
.

Like a stethescope?
 

Gold Member
Username: Magfan

USA

Post Number: 2280
Registered: Oct-07
Yes, until you want to characterize your result....and see exactly what a change does.

Accelerometers are easy these days. Stereophile uses one to determine cabinet resonant frequencies of speakers under test. They have deeper pockets than most individuals.
Consumer grade stuff is out there. A DIY oriented club could easily afford this one at 300$. It's USB and comes with software. Limits? max 100hz and poor resolution. If I found this in 30seconds, more/better is available.
http://www.motionnode.com/accel.html

Here is a link to a published aritlcle:
http://www.libinst.com/accel.htm

And the source for some of there parts: Sheets of piezoelectric film.
http://www.meas-spec.com/piezo-film-sensors.aspx

I've seen references to 'accelerometers on a chip' which can be made in many standard wafer fabrication facilities. Much more easily than even a simple logic device. These will be very affordable.

And, finally from the guys that got me thinking along these lines. And, for all of 35$
http://www.stereophile.com/features/806

Can you hear a stethescope in a room loud enough to make a shelf rattle? It's gonna get pretty loud, isn't it?
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16100
Registered: May-04
.

A bit more to it than spending $35, leo; "In first the February 1991 issue of Voice Coil, then the November issue (footnote 1), Editor Vance Dickason described a low-cost accelerometer made from a strip of the piezoelectric polymer PVDF (polyvinylidene fluoride) that enables impecunious engineers to get a more objective handle on cabinet problems. Costing just $35 plus shipping (footnote 2), the transducer consists of a 4" by 1" strip of PVDF attached to a small plastic block from which emerges a short pigtail of coaxial cable. The strip is securely taped to the surface to be analyzed; the output can be fed to any of the standard industry measurement systems.

As the transducer's source impedance is high and its output when used to examine cabinet resonances is in the few tens of microvolts, I constructed a 20dB-gain, op-amp-based buffer amplifier on perforated board, and used this to feed the input of the DRA Labs MLSSA system. Fig.1 shows a typical impulse response calculated by MLSSA from the output of the transducer used in this fashion with a 2kHz bandwidth drive signal. A relatively underdamped resonance with a peak amplitude of around 15mV can be seen ringing for about 80ms. (This response was actually obtained with the accelerometer taped to the top panel of the Monitor Audio Studio 15 that I review this month.) In a sense, this is but an objective version of the traditional "knuckle-rap" test, but it does enable the MLSSA system's diagnostic post-processing power to be brought to bear."



"Yes, until you want to characterize your result....and see exactly what a change does."


We're getting rather far into the woods with this but what you want to "characterize" is whether the change resulted in an improvement. That's all you need to know unless you intend to completely rebuilt whatever it is you are testing. If your inner geek says you need to know exactly the amount of change in dB's down to the second or third decimal point, then I suspect a simple listening device will not suffice. Otherwise, IMO, the intent of Dickason's suggestion falls somewhat outside of the interests of most hobbyists. No? It's a different hobbyist who is interested in damping the legs of their audio rack and the hobbyist who is interested in (re)building their speakers from the ground up. I've built my own speakers but delving into MLSSA software (http://www.mlssa.com/pdf/MLSSA-Brochure.pdf is more than I cared to do. In an audio club situation, yes, something like this, with someone who wanted to do the leg work, would be worthwhile. For the individual hobyyist, I don't know how much real world value there would be.


"Can you hear a stethescope in a room loud enough to make a shelf rattle? It's gonna get pretty loud, isn't it?"


Why would you turn it up to the point where it's "pretty loud"? Look, if things rattle when things get "pretty loud", then you have Andre-type problems and a dab of BluTak isn't going to change the situation. We sort of expect we are affecting a few things when we turn up the volume, right? So, we don't need to have 100dB+ in room to know that a particular frequency is the resonant point for, say, a shelf on an audio rack. I wouldn't suggest anyone use music as their test track for treating resonances. As Atkinson points out, in reality, all you need is a good sturdy knuckle.

Resonances are typically confined to a band of frequencies with the highest resonance being centered at the narrowest band of frequencies. How broad the bell of the resonance is will be determined by the materials, their shape and whatever damping has already been accomplished. We would normally be concerned only with those very wide bell or the high "Q" resonances when trying to damp something like a shelf or the leg of a stand. To get "geeky enough" to find these resonant frequencies you only need to use a simple test track with either, or both, stepped frequencies or an ascending/descending frequency sweep - though a knuckle will still stand in with admirable aptitude. It is the largest pressure waves which will excite a shelf or upright so we only can confine our test tracks to those frequencies beneath approximately 1kHz - and in reality probably only to those frequencies beneath about 400Hz. Anything above that frequency is more likely to be very high "Q" or have a very small band of frequencies which become problematic and, therefore, are probably not of much concern when it comes to resonance in supporting structures. You'll spend considerable time chasing down all the tiny, inevitable noises which exist when aiming at the highest level, broadband frequencies will get you where you want to go. IMO, if you're more @nal than that, you need to be buying something more exotic than a few hundred dollar rack.

Now, if you want to do a highly detailed analysis of your tonearm's resonant structure, then you are going to need a more sophisticated testing method. But for what Dak is interested in right now, tones beneath 1kHz should be fine. Start off at reasonable levels (beneath your average listening level) and start listening through the stethescope for any excitement of the surface in question. When a resonant frequency is hit, you'll recognize the change. It is typically the frequency more than the level that will give away the problems you need to address. If you hear nothing at the first volume level, step it up a bit and listen again. If it gets to the point where it's "pretty loud" before you notice any abnormalities, then you have to decide just how much can and should be done to alter that situation. But, by that point, there's probably quite a bit going on around you that you would also want to address.




Leo, I'm not arguing with you but I see limited use for your accelerometer where the average audio buyer is concerned. If you want to buy one and all the associated software, go for it. I was merely suggesting a fairly inexpensive, easy to source and simple to use tweak when I mentioned the stethoscope. My guess is we could all pick up a stethoscope and figure out how to make use of it to improve the damping in our systems without any instruction or ancillary software or materials.


What do you have against a stethoscope, leo?








.
 

Gold Member
Username: Magfan

USA

Post Number: 2282
Registered: Oct-07
I said it in my 2nd post: The 'Hi Tech' solution may be over the top and that a stethoscope would probably be fine....My only hangup with that technique revolve around use in a loud environment and the possible damping of what you are trying to hear by pressing down with the 'sensor' end of the 'scope.

I actually like the glass of water idea. Looking into a motorcycle mirror many years ago, I noticed that you could see the engine vibrations in the reflection of a point light. (at night)

Besides, I'm working on my Cold Fusion device and waiting for the wife to get home so I can use my new stethoscope to play doctor.

For the average guy? Accelerometer is near useless, unless you want to play with the limits of your cars acceleration and handling. I have the Level / Plumb Bob application for my Ipod Touch. The darn thing has a 3-axis accelerometer built in! But not useful for stereo aps.
The other possible use would be by a DIY audio club. Divide the cost up evenly and than share.

This stuff keeps getting less expensive and easier to use. Any of the DIY guys could make the op-amp in an hour out of the junk box. You've got to admit that a sensor that plugs into a USB port and comes with some simple software is an attractive idea to the home speaker builder. And, since you mention him, I'm surprised Andre doesn't have something like this already.

Some things are very low mass and attaching something like a sensor to them will change the system. In low mass systems like a tonearm? Maybe simply monitor the cartridge output?

And yes again, I'm using Google Sketchup to design a new rack. Vibration control is just one of the issues.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16103
Registered: May-04
.

"My only hangup with that technique revolve around use in a loud environment and the possible damping of what you are trying to hear by pressing down with the 'sensor' end of the 'scope."


I'm guessing you've never used a stethescope, leo.


.
 

Gold Member
Username: Dakulis

Spokane, Washington United States

Post Number: 1251
Registered: May-05
Well guys,

Whether stethoscope or water glass, at least I know what the point of the exercise is and you've given me a few options on how to attack it in previous posts. So, this weekend, I'll start with a water glass and if need be, I'll run down a couple doctor buddies and see if any have an old stethoscope they're willing to part with for awhile. Thanks, Dave
 

Gold Member
Username: Magfan

USA

Post Number: 2287
Registered: Oct-07
nope, but the doctor presses firmly when doing the heart thing.

The room is always fairly quiet, too.
 

Gold Member
Username: Dakulis

Spokane, Washington United States

Post Number: 1252
Registered: May-05
Well, the new stand passed the water test to listening levels that I would not normally listen. I didn't see any vibration at the mdf. Also, I have had the CD player and new amp on jenga blocks for about a week and comparing this to without. After some experimentation, I've gotten to jenga blocks under the amp with jenga blocks sitting under sorbothane feet on the CD. So far, a little better. I'll keep playing, racquets balls coming up . . . lol
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16120
Registered: May-04
.

BALLS UP!!!
 

Gold Member
Username: Dakulis

Spokane, Washington United States

Post Number: 1253
Registered: May-05
Jan,

I'm not sure if that's advice for love life, orientation for the cut racquet balls or a comment on my manhood. Dave
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16128
Registered: May-04
.

It is what it is, Dak.







lol!


.
 

Gold Member
Username: Dakulis

Spokane, Washington United States

Post Number: 1258
Registered: May-05
Jan,

Geez, I look for clarification and I get obfuscation. LOL
 

Gold Member
Username: Dakulis

Spokane, Washington United States

Post Number: 1259
Registered: May-05
Just to clarify, I'm talking about your failure to respond and not anything obfuscating my b@lls.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16136
Registered: May-04
.

My failure to respond?!!!


Crimeny, Dak, I've got over 16,000 posts! Surely, there must be a response in there somewhere that you like.




.
 

Gold Member
Username: Dakulis

Spokane, Washington United States

Post Number: 1262
Registered: May-05
Several. I'm a piker. I've got to write more I guess.
 

Gold Member
Username: Hawkbilly

Nova Scotia Canada

Post Number: 1317
Registered: Jul-07
Update on the Terrastones. Initial impressions have held up beautifully. They really do clean things up nicely. Overall presentation gets more focus, with less smearing of edges, which lets instruments really come alive. Imaging is improved as well. They are not cheap, as far as this type of thing goes I suppose, but they are well worth the money in terms of what they did for my system. I'd like to try a pair under each of my speakers sometime.
 

Gold Member
Username: Dakulis

Spokane, Washington United States

Post Number: 1264
Registered: May-05
Haven't gotten to the racquet balls yet. But, I decided to try the amp and CD with and without the jenga blocks. Ended up with the jenga blocks on the bottom with sorbethane discs on the CD.

I took the jenga blocks out from under the amp because it's not quite as bright. It was pushing the highs just a tad too high to where I was getting a little listener fatigue. As soon as they came out, the highs were still sharp but much easier to listen to.

This experimenting is kinda fun but does take some time to critically listen and see if you're improving things or just changing the sound and not necessarily getting closer to live.

Not sure that Terrastones are in my future unless they can be purchased at Wal-Mart prices. LOL
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 16194
Registered: May-04
.

Not to disparage the pricing of the Terrastones but you might consider something like a diy attempt at a similar product. Head over to the home improvement/remodel store and look at their "Corian" countertop samples. Most shops will have some 3X3" samples they will sell you for a few dollars. Then head to the area where you'll find ball bearings to locate some stainless steel or - better yet - silicon bearings. Or maybe the hobby/crafts store to buy some wooden balls. Finally over to the construction/plumbing dept, for some silicon caulk/adhesive. Stack two Corian samples together with a thin layer of adhesive between them and then adhere the bearing to the top of that surface. With the silicon adhesive, it's fairly easy to remove one bearing material and try another. If this works at all for you, consider the Terrastones.

Use your imagination, Dak. You can surely come up with a variation or two on what I've just described. Don't assume what you hear from the diy to be identical to the real aftermarket product but you can probably get an idea of where you want to head from some less expensive experiments. Presonally, I've always found Corian and marble/granite footers to be a bit toppy in my system and not within the bounds of my priorities. But interfaced with a different characteristic sound coming from, say, a bearing or spike made from a totally dissimilar material could be the answer. It's your system, your ears and your priorities. Yep, you eventually discard what doesn't work and don't just change for the sake of change. But with each new experiment you learn a bit more about what works and what doesn't within your priorites. Just keep it being fun or stop because then you're just chasing your tail for the sake of seeing if you can ever catch it.




.
 

Gold Member
Username: Hawkbilly

Nova Scotia Canada

Post Number: 1320
Registered: Jul-07
I actually did a marbles in corian experiment Jan. It worked pretty well with ceramic bearings. I found brass spikes on corian a little thin sounding (as you described, "toppy") but more robust with the marbles. These types of things are terrific for fine tuning your system, if you're looking to inch the overall sound one way of another.
Jump to: Home Audio Forum | Home Video Forum | Home Theater Forum | Car Audio Forum