View Full Version : Cinder blocks do really work. i had no idea.


Rex Aeterna
11-06-2011, 08:06 PM
about few days ago a friend suggested cinder blocks underneath my speakers as speaker stands and it will help the bass. i was thinking ''what? how that'll do anything''. so i decided to grab some from my friend across the street since he has tons of nice cinder blocks in his back yard from a project he never decided to start with. i put them under my speakers and what you know i notice no more boom behind the speaker and in the room..

i swear i couldn't explain it. i was not expecting anything at all to be honest but i always try to stay open minded to other peoples suggestions and experiment myself. cinder blocks was the last thing on my mind when i treated my room.

i have of course about 2'' thick carpet on my floor and ceiling and walls as well. it works wonderfully cleaning up the highs and midrange resonance of the room i'm in but did close to nothing for solving the bass boom but thanks to the suggesting of using cinder blocks it's no longer noticeable and gone. later on from doing lots of reading is cause cinder blocks are so dense that frequencies resonance get canceled out immediately since it has nowhere to go and acts like a great absorber/diffuser for bass frequencies around 100hz.

so now i'm gonna experiment and put one in every corner of my room as well to see if that does anything.

does anyone else use cinder blocks as acoustic treatment? i remember hearing some studios as well use cinder blocks as room treatment.

Naptown Rob
11-06-2011, 08:17 PM
It didn't have to be cinder blocks - it was raising our speakers that gave you that result....

JohnVF
11-06-2011, 08:18 PM
Did you have the speakers on the floor before? Getting them off the floor by the height of the block would help, no matter if its a block anything else sturdy. And if you get them up to where the tweeters are at ear level, the stereo imaging and sense of soundstage will improve.

Rex Aeterna
11-06-2011, 09:21 PM
they are floor standers so yes they were on the floor. i have a pair of Pioneer sp-fs51-lr speakers i use.

they were already ear level as well and since my chair can rise and lower even on the cinder blocks of extra height given they're still at ear level. they always were ear level before and after due to my chair able to adjust.

cinder blocks do give some acoustic benefits i believe from doing a lot of reading especially as stands since they don't reflect like plastic and metal stands do. the cabs themselves had good amount of polyfill inside already and is a curve cab design as well so cab resonance weren't that bad to begin with.

Soundminded
11-06-2011, 09:46 PM
"Cinder blocks do really work. i had no idea."

And if you put it on yourself it will cure cancer.

Rex Aeterna
11-07-2011, 12:12 AM
"Cinder blocks do really work. i had no idea."

And if you put it on yourself it will cure cancer.


are you making fun of? i can sense the sarcasm.

who knows. maybe it can. grind it up and mix it with some chocolate nesquick and it will cure every known disease known to man.

eteller
11-07-2011, 07:38 AM
Probably has to do with the mass of the blocks coupling the speakers to the floor. I have my Klipsch KG 4.2's on a concrete paver to raise them a little but really have not heard a difference but their about 4" too short.

kirk57
11-07-2011, 08:53 AM
Getting the speakers off the floor (how ever you accomplish this) is going to clean up bass response.

Concrete actually rings quite a bit, if you listen closely and tap on it. Sand or lead-shot filled metal stands are more inert (i.e. dead sounding) and generally considered the best type of stand. They are no doubt more expensive however.

Rex Aeterna
11-07-2011, 08:54 AM
maybe so.that can be it. i do also have about 2'' thick carpet on my floor as well besides my walls and ceiling.

read about speakers using concrete and concrete perfectly eliminates resonance. reading blocks are only good for 100hz or so. if it makes any sense i have it standing on the cinder blocks mouths pointing up and speaker on top of it. i guess any acoustic energy from the speaker and room gets trapped into the mouths and cause the density of the cinder block the energy just gets canceled out.

i heard stuffing fiberglass or sand as well can help absorb the lower frequencies under 100hz. i don't know if it'll matter much difference since my speakers can only extend down to around 40hz.

Rex Aeterna
11-07-2011, 08:57 AM
Getting the speakers off the floor (how ever you accomplish this) is going to clean up bass response.

Concrete actually rings quite a bit, if you listen closely and tap on it. Sand or lead-shot filled metal stands are more inert (i.e. dead sounding) and generally considered the best type of stand. They are no doubt more expensive however.


alright. but wouldn't metal be as bad or even plastic? it'll be better to just fill the concrete with sand or fiber glass since it'll be much cheaper and as effective.

kirk57
11-07-2011, 09:13 AM
alright. but wouldn't metal be as bad or even plastic? it'll be better to just fill the concrete with sand or fiber glass since it'll be much cheaper and as effective.

I suppose you could pour an inch or so of concrete on the bottom and then fill it it with sand. It's pretty easy to tell how much it is damped if you put your ear right up to it and tap.

If you have thick carpet, spikes would also help.

RevMen
11-07-2011, 11:14 AM
Probably has to do with the mass of the blocks coupling the speakers to the floor.
Using a massive stand between the speakers and the floor has exactly the opposite effect of "coupling."

Arkay
11-07-2011, 11:39 AM
1. Back "in the day" when a lot of our classic gear was new, MANY, MANY people on a budget used cinder blocks and boards as shelving to put their audio gear on. It was done because it was cheap and practical, not for any purported sonic benefits. WHO KNEW that this "cheapskate" approach was actually a sophisticated audiophile decision, aimed at taming errant bass? We were smarter than we knew! :D


2. One comment: cinder block is NOT exactly the same thing as concrete. It does NOT have the same resonance as poured/solid concrete.
From the "WiseGeek" website:
Cinder blocks differ from concrete blocks in other ways besides their hollow design. Concrete blocks are made from a slurry of Portland cement and small aggregate, such as small stones or gravel. Cinder blocks, on the other hand, are made from a combination of Portland cement and cinders, the dusty remnants of burned coal. The result is a lighter weight block formed into a rectangular masonry block. Although many people use the terms "cinder blocks" and "concrete blocks" interchangeably, a true cinder block will always be lighter than a concrete block, and the texture of cinder blocks may be rougher than finished concrete blocks.

3. The idea of using concrete and sand to damp a cinder block is perfectly valid. You could experiment with different "fillings" --grades of sand, lead shot, scrap metal shavings, poured rubber, etc... to see which best tames or "deadens" the resonances. An interesting experiment would be to put the cinder blocks horizontally, seal them inside with liquid rubber coating to make them water-tight, then fill them with water or (rubber-friendly) oil. Just don't crack/break them, or you'll really have a mess! :D

Rex Aeterna
11-07-2011, 03:15 PM
thanks Arkay! you were very helpful. that sounds like a good idea to me and thanks for letting me difference between cinder blocks and concrete blocks. personally i wouldn't of know. i guess i be hitting my friend up later on and go grab the rest in his backyard cause he has a whole bunch in there and in great condition as well but need some good cleaning cause they been sitting in the dirt for over a year or so.

MrGlobe
11-11-2011, 03:59 PM
I've used cinder blocks for speakers stands as well as a spot to put gear for a while now. Works great and stays cool even when the gear gets hot. Obviously I'd choose a nice rack and stands if I had the funds, but concrete does just fine. I don't think that putting concrete blocks all around the room will help. I think you are shooting for a DIY bass trap in a way, but you would be better off using Roxul Rockwool in the corners. If you think the concrete stands helped your speakers sound better, try out some good acoustic foam in the corners and at the first reflections. It's amazing what it does for the sound

perryinva
11-11-2011, 06:50 PM
ok. NO one mentions anything about him saying the walls and ceiling are carpeted, same as the floors? Is this a real thread?

jt45
11-12-2011, 08:58 AM
ok. NO one mentions anything about him saying the walls and ceiling are carpeted, same as the floors? Is this a real thread?

I agree, another thing is Cinder Blocks ARE NOT the same as concrete, they are actually very porous and quite capable of absorbing/damping LF vibrations.
While a agree that getting them off the floor helps, the OP is correct in that the Cinder blocks also work as described. Concrete is much more dense and could work against damping whereas Cinder Blocks are Porous (Sponge like)
Cinder blocks are no longer made from with cinder but the name has stuck around, they do have the similar ingredients and certain grade blocks are more dense (concrete Like) and wouldn't be as well suited for this.

I would not use cinder blocks as a room treatment.

Using Blue tack or some form of clay or putty will basically absorb resonance
vibrations with most stands and you wont have a pile of blocks in your room.
The WAF factor for Block stands would be rather low here. :D

1audiohack
11-12-2011, 11:32 AM
Here in Las Vegas we have a cinder block company that still mines a volcano for cinder for there products.

carcrazy
11-12-2011, 11:52 AM
I have used concrete paving bricks (the interlocking kind) to form a base for my downward firing M&K MX-70 subs (2 drivers in a push-pull design). Wood blocks were placed between the concrete bricks and the subs.

They were on carpet before and I found that using the paving bricks tightened up the bass. The carpet may have been over damping the subs before. I am not sure what the resonant frequency of these bricks were but I didn't hear any ringing (louder at a certain frequency) when I tested the system with a frequency sweep from a test cd. It worked for me. And the red color of the bricks went well with the red Tetra 406 speakers.

Rex Aeterna
11-12-2011, 02:00 PM
I've used cinder blocks for speakers stands as well as a spot to put gear for a while now. Works great and stays cool even when the gear gets hot. Obviously I'd choose a nice rack and stands if I had the funds, but concrete does just fine. I don't think that putting concrete blocks all around the room will help. I think you are shooting for a DIY bass trap in a way, but you would be better off using Roxul Rockwool in the corners. If you think the concrete stands helped your speakers sound better, try out some good acoustic foam in the corners and at the first reflections. It's amazing what it does for the sound


yea. my idea was use the cinder blocks as a base and fill it with fiberglass or something and have it stand horizontally as suggested in the corners. they are pretty light since they're cinder blocks and i only have couple corners in my room so not like it'll be everywhere. might add couple under my table as well maybe but it's only an idea.

Rex Aeterna
11-12-2011, 02:06 PM
I agree, another thing is Cinder Blocks ARE NOT the same as concrete, they are actually very porous and quite capable of absorbing/damping LF vibrations.
While a agree that getting them off the floor helps, the OP is correct in that the Cinder blocks also work as described. Concrete is much more dense and could work against damping whereas Cinder Blocks are Porous (Sponge like)
Cinder blocks are no longer made from with cinder but the name has stuck around, they do have the similar ingredients and certain grade blocks are more dense (concrete Like) and wouldn't be as well suited for this.

I would not use cinder blocks as a room treatment.

Using Blue tack or some form of clay or putty will basically absorb resonance
vibrations with most stands and you wont have a pile of blocks in your room.
The WAF factor for Block stands would be rather low here. :D

i appreciate your suggestions. i will look into blue tack as well. i only use carpet on my floors,ceilings and walls cause i got them for free cause i use to help with home improvements and rentals so i grabbed up some nice thick persian carpets for my floor and ceiling while used other carpet i took for the walls. people might find it odd using carpet instead of expensive fancy acoustic panels but i don't care really as long as it gets the job done. also it's pretty cool laying down and looking up on the carpet designs using your imagination.

carcrazy
11-12-2011, 02:27 PM
That sounds pretty shagalistic. Got any pics of this man cave?

Rex Aeterna
11-12-2011, 02:49 PM
That sounds pretty shagalistic. Got any pics of this man cave?

only have this one. it's an old pic.

http://i882.photobucket.com/albums/ac26/RexAeterna/DSC01046.jpg


you can't see it since cam i used was a crappy sony cam but the same carpet on the ceiling is on the floor. some things has changed since cause i sized down to only one pair of speakers and use a different monitor since one in the pic went( i loved that sony GDM-FW900 CRT. still have it sitting around cause i was told possibly the flyback transformer went so it can be fixed.can't buy a new FW900 one cause they still go for over 900 bucks in value.)

carcrazy
11-12-2011, 03:08 PM
Cool.

jt45
11-12-2011, 04:50 PM
I come from a long line of carpet layers back in the 70s I used to help my father install all that orange or green shag that was the rage back then. It was quite common to install that stuff everywhere Floors, Ceilings, walls, cars , boats, houseboats and lets not forget those custom vans (everything including the kitchen sink). Before hotmelt seam tape came along I spent untold hours sewing carpet seams together for my father.
Years later as soon as I could, I got away from that trade, I think that shag haunts me.

Anyway that stuff does a fine job like you have it, sorry for the ramble I buried my father this week and the carpet thing had me remembering those days when we were a team.

carcrazy
11-12-2011, 06:23 PM
Sorry to hear that, my condolences.

Fred S
11-13-2011, 10:19 AM
I am a machinist by trade. One thing that machining and audio have in common is a desire to eliminate unwanted vibrations. Audiophiles talk about speakers being coupled to the floor, or about isolating the turntable. Machinists talk about machine resonance and chatter.

The normal way to reduce chatter in a machine tool is through mass. The machines weigh several tons. But with the advent of bench top machines, other solutions have to be found.

Some manufacturers have switched to using epoxy granite to fill voids in their machine bases. Or in some cases, the entire machine base is made of the stuff.

Epoxy granite is exactly what it sounds like. Epoxy and granite mixed together.
http://en.wikipedia.org/wiki/Epoxy_granite

It's relatively cheap, and it damps vibration better than metal. So I find myself wondering if it has any audiophile applications.

Frederic

RevMen
11-13-2011, 11:52 AM
Audiophiles talk about speakers being coupled to the floor
An incorrect yet prevalent idea. Speakers should be isolated, just like turntables or amps or anything else when you're trying to cut down vibration.
Epoxy granite is exactly what it sounds like. Epoxy and granite mixed together.
http://en.wikipedia.org/wiki/Epoxy_granite

It's relatively cheap, and it damps vibration better than metal. So I find myself wondering if it has any audiophile applications.
That's cool stuff! Although it is more pliable than granite or cast metal, it's still very stiff compared to the masses of audio components. It works well for very heavy objects like machine tools, but to a five or even thirty pound speaker it wouldn't appear to be much different than stone, I don't think. Not so good for vibration isolation or damping in that case.

I wonder if it could be formed into a speaker box, though? How much does it cost, and is it difficult to form?

Permanent Waves
11-13-2011, 02:17 PM
Getting the speakers off the floor (how ever you accomplish this) is going to clean up bass response.

Concrete actually rings quite a bit, if you listen closely and tap on it. Sand or lead-shot filled metal stands are more inert (i.e. dead sounding) and generally considered the best type of stand. They are no doubt more expensive however.

This. Solid stands filled with the proper material will help speakers sound better by at least somewhat-slightly detectable standards.

I've heard the same speakers with the same stands filled and unfilled, blind, and we picked the filled stands as sounding slightly better. It's not day/night, but it does help, especially the more "hi-fi" (resolving) the speaker.

kerrytat2
11-13-2011, 06:47 PM
My 2 cents:D

Compgeke
11-13-2011, 07:38 PM
I'm using cinder blocks also, they work to keep the speaker off the floor, and that was all I was worried about so if anything gets spilled on the floor the speakers don't get wet.

Rex Aeterna
11-13-2011, 07:46 PM
This. Solid stands filled with the proper material will help speakers sound better by at least somewhat-slightly detectable standards.

I've heard the same speakers with the same stands filled and unfilled, blind, and we picked the filled stands as sounding slightly better. It's not day/night, but it does help, especially the more "hi-fi" (resolving) the speaker.


thing is my speakers barely suffer from much resonance to begin with cause they are stuffed well and the cabs are curved and was on 2'' thick carpet so it shouldn't of suffer of any type of resounance issues some might think it could of. i use cinder blocks,not concrete(from what i learned here cause there seems to be a difference between actual cinder blocks and concrete). i tap on it and there is no ringing from it. i still plan on stuffing them soon though. i just need to find time to do so since i been busier nowadays with some stuff.

jt45
11-13-2011, 07:58 PM
Seems like there are several ways to cut down on Vibrations and its not limited to just
one thing, I see many folks using Extra weight in their stands as well as using some type of damping material between the Speaker cab and stand, OR FLOOR, I just recently got a pair a stands thrown in on a pair of Bookshelf speakers I bought, the stands have threaded inserts for carpet spikes but are missing the spikes so Iv'e been reading up and looking for some spikes that would serve several functions such as stability, Isolation and leveling abilities as well as helping to pinpoint the weight, I think this is why the term coupling is used. Here is an advert explanation i found wich covers some of those points,

(QUOTE) Speakers produce sound by moving a paper-cone back and forth, thus pushing on the air in your room. Air, due to a property called inertia, tries to resist motion. So, the speaker ends up exerting force against its own cabinet instead. This causes the cabinet to move. If you can prevent the cabinet from moving, more of the energy is used to move the air, rather than your cabinet. More air movement means more sound. The easiest way to keep your speaker cabinet from moving is to place it on a hard surface. If you place it on a soft surface like carpet or rubber, it can move too easily. Installing spikes on the bottom of your speaker cabinet allows it to essentially reach through the carpet (and padding) and onto the hard floor below.

But the cone-shape of a "spike" serves a dual function. It focuses all of the weight of the speaker onto a single point. If the base of your speaker measures 10" x 10" (100 square inches of surface area) and weighs 100 lbs., that equals 1 pound per square inch exerted onto the floor. Now, by placing your speaker on cones you can reduce the surface area to an tiny point that may exert thousands of pounds per square inch onto the floor. If your speaker had any thoughts about moving, it may as well forget about it!

On the other hand, imagine that you are the floor. A floor that likes to vibrate. Now imagine what it would take to move an object that is exerting a force of thousands of pounds per square inch. Just like the speaker, you can forget about it.

As you can see, the cones allow mechanical energy from the speaker to be absorbed by the floor, but will not allow energy in the floor to reach the speaker. Think of it as a one way street for vibration. (I hope Isaac Newton isn't reading this) The bottom line: Spikes make your system sound better (End quote)

RevMen
11-14-2011, 12:17 AM
As you can see, the cones allow mechanical energy from the speaker to be absorbed by the floor, but will not allow energy in the floor to reach the speaker. Think of it as a one way street for vibration.
It doesn't work that way. Vibration waves require atoms to move in both directions, back and forth, or else the wave couldn't transfer across in the first place. It's not possible for there to be a one-way valve for vibration (there's is a thread here about a theoretical one-way wall for sound, but that doesn't exist yet).

Spikes isolate vibration by creating a high vibrational impedance difference between the floor and the speaker. Impedance depends in part on the surface area, a large area that has a sudden connection to a small surface area doesn't let vibration through as efficiently.

If you imagine swapping the densities of the speaker/spike/foor and the air around them, you can recognize that the same system works when air is the vibration medium. If you are in one room and your friend is in the room next to you, she can hear you speaking pretty clearly if there is a big hole in the wall separating your rooms, but she'll have a hard time hearing you if there is just a small hole. It's the same situation. A sound wave, which operates under the same principals as a vibration wave moving through a solid, reaches a major change in surface area, causing most of the sound energy to bounce back with only a small amount diffracting through the hole in the wall.

If the argument is that a set of spikes will give a speaker a better grip on the floor to resist horizontal movement of the cabinet due to movement of the cone, I guess that makes some sense in a carpet situation (assuming the spikes go into the actual carpet), though I don't know if the amplitude of those motions are in the range where the type of surface the cab is sitting on matters. If it's hard spikes on hard, flat floors, then I would be inclined to think that a flat contact patch between the cabinet and the floor would do a better job of resisting movement than spikes. It seems to me a cabinet sitting on spikes would be easier to slide across the floor, unless they're so sharp they actually pierce the wood and leave a mark.

The reason you would want to isolate a speaker from the structure of your house is walls, ceilings, and hard floors make great re-resonators. If you're efficiently transferring vibration into your building structure, you're creating additional speakers all around you that can deteriorate the timing and phase information that allow your ears to create a stereo image, or introduce comb filtering that affects tone quality.

jt45
11-14-2011, 06:24 AM
Your missing the point it seems, those were Advertisement words, First your saying the speaker needs to be Isolated then you say it doesn't work that way, Oddly enough thats exactly what people have been using for decades to Isolate and stabilize their speakers and gear in some cases . I think the the main focus of Spikes is to provide a stable platform through the carpet to the floor and they are usually sharp enough to do that.

RevMen
11-14-2011, 10:53 AM
I said "it doesn't work that way" about the "one-way street for vibration." The spike is a Do Not Enter sign on both sides, not a One Way.

I'm trying to explain that speaker spikes do not provide any coupling between a speaker and the floor, which is a commonly held misconception. They do act as vibration isolators, which is a function exactly the opposite to coupling. By definition, you can't have both.

I have seen plenty of advertisements for speaker spikes with various wrong explanations for why they work. I have seen some that are correct. The concepts at play aren't intuitive, so mistakes are made, and it's not at all necessary to understand how a speaker spike works to be able to sell one.

And none of this means that spikes actually provide enough isolation to be effective. I see no reason to believe they'd be as effective as a damping type of isolator, like neoprene rubber feet or pads.

Another theory that I think is actually more likely to be useful, is that spikes provide a stable platform for a speaker. An object sitting on a floor with exactly 3 points of contact is always stable, as long as the center of mass is inside the triangle formed by the points. A stable stance means no "rocking" will occur due to the speaker (or stand) setting on the floor. A carpeted floor might allow the speaker to rock a little due to compression of the carpet fibers underneath, or a hard floor might allow a speaker to rock a little due to an interface between two surfaces that aren't perfectly flat. I don't actually know if this occurs, but it seems reasonable enough.

Brett a
11-14-2011, 11:28 AM
I'm still a little surprised that I get surprised by all the naysayers around here.
Yes, elevating speakers to ear level is essential, but concrete makes much better stands b/c of mass. For years, I had my AR93 floorstanders up on milk crates. Eventually I tried cinder blocks instead. Didn't change the height, just the mass of the stands, and I was amazed at the improvement just as the OP is reporting.

I then experienced even grater improvement by installing spikes screwed into the speaker bases and then set back down on the cinder blocks. It was so good it made me hungry for even better speakers (that's why i have the ones I have now)



An incorrect yet prevalent idea. Speakers should be isolated, just like turntables or amps or anything else when you're trying to cut down vibration.
Prevalent, but not wrong. Speakers need to be held solidly in space for increased accuracy and clarity.

Since all that drivers are are air pistons, they need as solid a mount as possible to press against when they move the air in a room. When the cone moves forward, it ideally should not move the cabinet back even a tiny bit. You'll get smearing of the soundstage and muddying of the bass to the extent that the cabinets are allowed to vibrate in response to the drivers pushing and pulling air.

I've found that bracing or weighting speaker cabinets always improves imaging and clarity. This is also why movie theater subs are often mounted in huge concrete boxes.

And this is also why cinder blocks make better speaker stands than milk crates.

I'm curious to know why isolation would work to an advantage? I can't think of why...

Gibsonian
11-14-2011, 01:46 PM
I've found that spikes reduce movement of the speaker box. I have heavy subs on concrete floor but these would move when sitting flat to floor or even with rubber placed on three places or four, such is the power I put through them. I eventually glued wood blocks to floor and now use 3 spikes, and the spikes are stuck into the wood blocks. Bass is tighter and more defined as I've coupled the boxes to a nearly immovable concrete garage floor. The only movement I would have would be micromovement of the spikes in the wood or the flexing of the spikes to some small degree. I do have vibration in the room but it is due to sound waves in air - I do not think I am moving a 4 ton concrete object.

RevMen
11-14-2011, 03:23 PM
Prevalent, but not wrong. Speakers need to be held solidly in space for increased accuracy and clarity.
The "wrong" idea I'm referring to is that spikes are couplers. I'm not arguing that bracing a speaker is a bad idea. It probably is a good idea, but that's not the same thing as coupling the mass of the speaker cabinet to the mass of the floor.

I'm curious to know why isolation would work to an advantage? I can't think of why...

The reason you would want to isolate a speaker from the structure of your house is walls, ceilings, and hard floors make great re-resonators. If you're efficiently transferring vibration into your building structure, you're creating additional speakers all around you that can deteriorate the timing and phase information that allow your ears to create a stereo image, or introduce comb filtering that affects tone quality.

RevMen
11-14-2011, 03:38 PM
I do not think I am moving a 4 ton concrete object.
You'd be surprised. You don't have to move the entire foundation at once to transmit vibration into it that can be re-radiated elsewhere in your house. Vibration in concrete is no different than vibration in air; one atom bumps the next, which bumps the next, which bumps the next...

It's your concrete's high density, not mass, that results in an impedance difference compared to air (http://en.wikipedia.org/wiki/Acoustic_impedance).

media
11-16-2011, 02:32 PM
My speaker stands (if you can call them that) are just cinder blocks spray painted black with a little shelf liner on top so the concrete doesnt scrape up the bottom of the speaker. you cant even tell what they are unless you got down on your hands and knees to look really closely. Some day I'm sure I'll track down some actual stands, but this is pretty good in the meantime.

Rex Aeterna
11-16-2011, 02:44 PM
i decided to grab more cinder blocks from my friend across the street. i grabbed up 4 more from him and cleaned them. i put extra one underneath my speakers and the extra cinder block helped lot more keeping the speaker much more firm and makes zero movement. you can't even feel a single thing through the cinder blocks and the bass become even more ''dead'' or you can say ''tight/dampened''. i have two extra blocks still and wonder what i should do with them. i was thinking of sticking behind me or under my table behind the stereo cab maybe.