DIY Subwoofer Risers

[Big Daddy]

Originally Posted by Badas

So I am going to get something custom made. Black steel speaker stands. For the front 2 Subs.

So do I,

1. Put spikes on the bottom of the stands?
2. Is two foot height recommended? I see some are a lot lower.
3. Do I put a rubber pad or something between the stand and the subs?
4. Going to leave the back sub. Should I take the spikes off?

Thanks for all your help Big Daddy. On this and other threads.

Ta

Dono

Attach rubber isolation feet to the bottom of the subwoofer and the bottom of the riser.

Most commercially available risers or most DIY risers only deal with isolation from the floor. As I explained in post #2, the other important factor we need to deal with is the vertical axial modes. You can only do that by putting a subwoofer on a tall riser or hang it from the ceiling. The 25% (2 ft) rule is an approximate rule that works for most 8ft high rooms in the U.S. (two feet is 25% of 8 feet). For all practical purposes, the subwoofer should be located at least 25 percent away from the boundaries to best avoid stimulating any of its first three harmonics. To fully understand this, read A Guide to Subwoofers (Part II): Standing Waves & Room Modes at your own risk.

A few of our members have built risers like that. When you raise a subwoofer that high, you should really fill the gap under the riser with dense material.

The only commerically available ones are SubTraps sold by ASC and they are very expensive. Check Post #3 for additional information on SubTraps.

SubTrap1.jpg
SubTrap2.jpg SubTrap3.jpg

18” SubTrap (50 Hz) Standard, most Subwoofers: $469
22” SubTrap (30 Hz) Large Subwoofer: $586
http://www.asc-home-theater.com/subtrap.htm

Once you hear the difference, you’ll never go back. The SubTrap is more than a simple isolation stand. In addition to isolation, it absorbs excess bass and decouples your sub-woofer from room mode. The end result is a unique product available only from ASC. Raise your subwoofer up to its full performance potential. Just slip the ASC-SubTrap underneath your subwoofer and you’ll create the powerful “SubStack.” Instantly improve bass detail, changing “muddy” low frequency playback into a richly detailed picture. Not only does the SubTrap increase bass extension and punch, it also gets rid of "one note bass.

By raising the sub off the floor and putting a SubTrap under it, the subwoofer is effectively decoupled from the vertical room mode. Excess bass buildup is reduced and the playback volume of the subwoofer can be cranked up much higher than before.

Reviews:
http://hometheaterhifi.com/volume_12...ap-6-2005.html
http://www.stereophile.com/musicinth...ic/index1.html

[crazyBLUE]

^^^^^^^^^^^^^^

Only Crazy people build risers like that

[Badas]

You mean Crazy, Crazy, Crazy, Crazy, Crazy Blu like you.

How did you find it?

[crazyBLUE]

Originally Posted by Badas

You mean Crazy, Crazy, Crazy, Crazy, Crazy Blu like you.

How did you find it?

Hi Dono

Is your question directed at me ? What did I find

[Badas]

Originally Posted by crazyBLUE

Hi Dono

Is your question directed at me ? What did I find

Yeah Brent,

I noticed your front Sub is at least a foot off the floor and your back one is about 2 foot high.

Did you notice a big difference from being on the floor?

I'm thinking of isolating mine using a base, however I probably won't elevate to 2 foot high. However I'm curious about the effect.

Ta

Dono

[Hammie]

This message is going out to Big Daddy (or any other member who may have thoughts on this question).

I recently postsed a comment in my HT gallery thread, but thought I would ask the question here. I think this is the right place to post this. If not, please place in the correct area.

Anyway, to my question...

Will a 2.25" carpet spike make a difference in bass reproduction in a room?

I recently added some 2.25" carpet spikes to my SVS PB12-NSD sub and I feel the bass has changed form a rumbly type of bass to a bass that just rattles my room. Does this make sense? I think the new carpet spikes only raised it 1.75" from where it was before with the "stock" rubber feet. That is another difference. The other feet are rubber and basically just sat on the top of the carpet. The new feet are black chrome nickel feet and they pierce the carpet and rest on the concrete beneath my carpet.

Any thoughts would be greatly appreciated.

[Big Daddy]

Originally Posted by Hammie

This message is going out to Big Daddy (or any other member who may have thoughts on this question).

I recently postsed a comment in my HT gallery thread, but thought I would ask the question here. I think this is the right place to post this. If not, please place in the correct area.

Anyway, to my question...

Will a 2.25" carpet spike make a difference in bass reproduction in a room?

I recently added some 2.25" carpet spikes to my SVS PB12-NSD sub and I feel the bass has changed form a rumbly type of bass to a bass that just rattles my room. Does this make sense? I think the new carpet spikes only raised it 1.75" from where it was before with the "stock" rubber feet. That is another difference. The other feet are rubber and basically just sat on the top of the carpet. The new feet are black chrome nickel feet and they pierce the carpet and rest on the concrete beneath my carpet.

Any thoughts would be greatly appreciated.

I will repeat what I stated earlier.

Risers, stands, and isolation feet can have three effects:

1. Raising the tweeters of bookshelf speakers and bringing them up to ear level. It is recommended that the tweeters of the front speakers should be at ear level.
2. Isolation and decoupling from the floor and reduction in the energy transfer and vibrations between the floor and speakers/subwoofers. Hearing this benefit may be a bit difficult and hard to quantify.
3. Changing the nature of the interaction between the waves and the room boundaries. This effect is usually more pronouced, particularly in the case of subwoofers and their effect on vertical room modes.

ISOLATION EFFECT

Normally, the best solution to achieve better bass response in a room is optimal subwoofer placement or using multiple subwoofers. Unfortunately, there may be another problem. The other objects in the room may vibrate due to secondary resonances. This problem may require a different type of solution to absorb vibrations and reduce secondary resonances.

A secondary resonance occurs when lower frequencies cause other objects in the room such as furniture, walls, pictures, and even other speakers, to vibrate. An isolation pad/stand is designed to isolate the speakers/subwoofers and prevent vibrations from transmitting to other objects. It allows the listener to hear the source by reducing vibrations from other objects.

In the case of a subwoofer, the frequencies that cause secondary vibrations are harmonic frequencies above 100Hz, up to about 250Hz. By controlling these vibrations and harmonic frequencies, the fundamental frequencies below the crossover point (80Hz to 120Hz) will be reproduced with no interference, resulting in better definition and greater clarity of bass frequencies.

Many believe that rubber isolation feet are better for controlling these secondary vibrations. However, spikes on a carpet, particularly a thick carpet with lots of padding, can play the same role.

[aces high]

Originally Posted by Big Daddy

I will repeat what I stated earlier.

Risers, stands, and isolation feet can have three effects:

1. Raising the tweeters of bookshelf speakers and bringing them up to ear level. It is recommended that the tweeters of the front speakers should be at ear level.
2. Isolation and decoupling from the floor and reduction in the energy transfer and vibrations between the floor and speakers/subwoofers. Hearing this benefit may be a bit difficult and hard to quantify.
3. Changing the nature of the interaction between the waves and the room boundaries. This effect is usually more pronouced, particularly in the case of subwoofers and their effect on vertical room modes.

ISOLATION EFFECT

Normally, the best solution to achieve better bass response in a room is optimal subwoofer placement or using multiple subwoofers. Unfortunately, there may be another problem. The other objects in the room may vibrate due to secondary resonances. This problem may require a different type of solution to absorb vibrations and reduce secondary resonances.

A secondary resonance occurs when lower frequencies cause other objects in the room such as furniture, walls, pictures, and even other speakers, to vibrate. An isolation pad/stand is designed to isolate the speakers/subwoofers and prevent vibrations from transmitting to other objects. It allows the listener to hear the source by reducing vibrations from other objects.

In the case of a subwoofer, the frequencies that cause secondary vibrations are harmonic frequencies above 100Hz, up to about 250Hz. By controlling these vibrations and harmonic frequencies, the fundamental frequencies below the crossover point (80Hz to 120Hz) will be reproduced with no interference, resulting in better definition and greater clarity of bass frequencies.

Many believe that rubber isolation feet are better for controlling these secondary vibrations. However, spikes on a carpet, particularly a thick carpet with lots of padding, can play the same role.

I'm using a Great Gramma and I still great objects in the room vibrating. I used to have dual subs and had an extra Gramma lying around, so I stacked them on top of each other. It didn't make any difference, what is something else I could use for a riser?

[Big Daddy]

Originally Posted by aces high

I'm using a Great Gramma and I still great objects in the room vibrating. I used to have dual subs and had an extra Gramma lying around, so I stacked them on top of each other. It didn't make any difference, what is something else I could use for a riser?

You can add rubber vibration isolation pads or spikes to the bottom of the subwoofer.

http://www.av-outlet.com/index.html?...tml&lang=en-us
http://www.soundproofcow.com/sound-i...n-control.html
http://www.drillspot.com/tag/vibration-isolator/
http://www.fullcompass.com/product/316672.html
http://www.fullcompass.com/product/239266.html
http://www.fullcompass.com/product/239265.html
http://www.fullcompass.com/product/239264.html
http://shop.ebay.com/items/?_nkw=spe...ikes&_osacat=0
http://www.parts-express.com/wizards...hFilter=spikes

If you get desparate, you can go to a sporting goods store and buy a few hockey pucks and attach them to the bottom.

Make sure your subwoofer is calibrated properly and is not set too hot. Changing the location of the subwoofer can also help. If you build a riser and get it off the floor, it is possible that the vibration may stop. Add rubber isolation feet to the bottom of the riser.

[aces high]

Originally Posted by Big Daddy

You can add rubber vibration isolation pads or spikes to the bottom of the subwoofer.

http://www.av-outlet.com/index.html?...tml&lang=en-us
http://www.soundproofcow.com/sound-i...n-control.html
http://www.drillspot.com/tag/vibration-isolator/
http://www.fullcompass.com/product/316672.html
http://www.fullcompass.com/product/239266.html
http://www.fullcompass.com/product/239265.html
http://www.fullcompass.com/product/239264.html
http://shop.ebay.com/items/?_nkw=spe...ikes&_osacat=0
http://www.parts-express.com/wizards...hFilter=spikes

If you get desparate, you can go to a sporting goods store and buy a few hockey pucks and attach them to the bottom.

Make sure your subwoofer is calibrated properly and is not set too hot. Changing the location of the subwoofer can also help. If you build a riser and get it off the floor, it is possible that the vibration may stop. Add rubber isolation feet to the bottom of the riser.

My sub is the Paradigm Sub 15 and it comes with isolation spikes, it's also well calibrated with the Perfect Bass Kit and an SPL meter. How will a riser differ from a Great Gramma? Right now I have them stacked two high with the sub on top of them, the spikes at the back are on the Gramma but the front ones aren't. The cabinet is curved and wider at the front than the back, I'm using some rubber door stops to level the sub from front to back. Would a properly sized riser with isolation feet and hockey pucks underneath work better?

[Big Daddy]

Originally Posted by aces high

My sub is the Paradigm Sub 15 and it comes with isolation spikes, it's also well calibrated with the Perfect Bass Kit and an SPL meter. How will a riser differ from a Great Gramma? Right now I have them stacked two high with the sub on top of them, the spikes at the back are on the Gramma but the front ones aren't. The cabinet is curved and wider at the front than the back, I'm using some rubber door stops to level the sub from front to back. Would a properly sized riser with isolation feet and hockey pucks underneath work better?

A riser that is a couple of feet high deals with vertical axial modes. The gramma only deals with isolation from the floor and does not do much as far vertical axial modes are concerned. If you build a riser, make sure you attach rubber isolation feet to its bottom and also to the bottom of the subwoofer.

[Big Daddy]

Aces High,

If nothing else helps, your room may need some treatment. It may be a very good idea to start with 4 or more bass traps.

http://www.thefoamfactory.com/acoust...bassbroad.html
http://www.gikacoustics.com/gik_tri_trap.html

[crazyBLUE]

Originally Posted by Badas

Yeah Brent,

I noticed your front Sub is at least a foot off the floor and your back one is about 2 foot high.

Did you notice a big difference from being on the floor?

I'm thinking of isolating mine using a base, however I probably won't elevate to 2 foot high. However I'm curious about the effect.

Ta

Dono

Dono

The riser I made for the front 15" sub is a foot tall. I have never had it on the ground to test but it is a monster & the bass coming from it being raised up & just below the screen really gives a good blend of what you are seeing & hearing in a movie.

My 2 rear subs are really cool sounding being up at ear level to either side. They are about 38" off the floor & really enhance how the Bass is in the room I think. It is vary hard to tell where the Bass is coming from with them setup the way they are.

[darien87]

Hello folks,

Lots of good information here. I've heard good things about the Auralex Gramma but think that it is a bit pricey for what it's made of. I have 2 subs in my system. I have a Rythmik 12" sub in a sealed enclosure that is in the front left of my living room and a DIY 15" sub with two 18" PR's at the rear right of my room.

The Rythmik has 4" legs to raise if off of the floor. The 15" is on casters that raise it about 2" off of the floor. The living room is carpeted.

If I build risers for them I don't want them to be too high, because frankly I think it just looks weird. So I was thinking about making platforms about 4" high or so. I am mainly concerned with the larger 15" sub. If I put it on a riser, should I put "hockey pucks" under each of the casters or will putting it on the riser be enough?

Also, I noticed that some of you don't have the foam under the platform going all the way to the floor. But the Auralex products seem to have the platform supported by the foam itself. So I am a little confused at how the home made products can work as well. If it is the foam that is doing the decoupling, what is the difference between having a riser with legs and just having the sub on the floor, (as far as decoupling is concerned)? I would think that wooden riser legs would vibrate the floor just as well as having the sub itself on the floor.

[Big Daddy]

Originally Posted by darien87

Hello folks,

Lots of good information here. I've heard good things about the Auralex Gramma but think that it is a bit pricey for what it's made of. I have 2 subs in my system. I have a Rythmik 12" sub in a sealed enclosure that is in the front left of my living room and a DIY 15" sub with two 18" PR's at the rear right of my room.

The Rythmik has 4" legs to raise if off of the floor. The 15" is on casters that raise it about 2" off of the floor. The living room is carpeted.

If I build risers for them I don't want them to be too high, because frankly I think it just looks weird. So I was thinking about making platforms about 4" high or so. I am mainly concerned with the larger 15" sub. If I put it on a riser, should I put "hockey pucks" under each of the casters or will putting it on the riser be enough?

Also, I noticed that some of you don't have the foam under the platform going all the way to the floor. But the Auralex products seem to have the platform supported by the foam itself. So I am a little confused at how the home made products can work as well. If it is the foam that is doing the decoupling, what is the difference between having a riser with legs and just having the sub on the floor, (as far as decoupling is concerned)? I would think that wooden riser legs would vibrate the floor just as well as having the sub itself on the floor.

The higher the riser, the more benefit it may have. It is a good idea to put rubber isolation feet between the subwoofer and the riser and also underneath the riser. Make sure the subwoofers are stable and are not rocking back and forth. Go back and review posts #2 and #3 of this thread.

[rana_kirti]

guys anyone able to compare subdude vs subdude hd ....??

i need one for my just arrived svs pc 12 nsd. and i cant make up my mind between the 2....

[Big Daddy]

Originally Posted by rana_kirti

guys anyone able to compare subdude vs subdude hd ....??

i need one for my just arrived svs pc 12 nsd. and i cant make up my mind between the 2....

I haven't used either one, but I believe the difference is mostly cosmetics. One is gray and the other one is black. I believe the Subdude HD has a smoother top and can be cleaned with a damped towel.

[rana_kirti]

big daddy.... i dont know how many times i've thanked you for your help.... you've really helped me a lot with many different queries...

Cheers to you....

[Badas]

+ 1

Thanks to all your help.

[28BlusLater]

I have the SVS PB12-NSD and am thinking about getting a subwoofer riser from Elemental Designs. I got a new AV rack (not yet in the HT gallery) and my center channel is now at ear level and WOW, what a difference.
My front speakers are a little under ear level, I'd say a few inches. Are risers recommended?
Is there an easy way to make risers for my fronts and if there is an easy way to make one for my SVS PB12-NSD, I'd love to know to save the $65 on the sub riser. However, I'm pretty bad with building stuff, so I'd need to find basically a full step by step. I went through a few pages of this thread and can't find a riser that will hold my subwoofer since it's not just heavy, but pretty long.
I got an e-mail back from Elemental Designs. They say that the riser for the A5-350 will best fit my subwoofer.
Here's the link:
http://www.edesignaudio.com/product_...roducts_id=945
What do you guys think?
Just as a side note, my room has carpeted floors.