Quiet Drawer slides for subwoofer

[Rob Price]

Okay, I'm in the middle of a built in entertainment center for a newly finished basement media room. Part of the deal with the wife was that I could go all out on the AV equip (as much as the budget could take that is) but it had to have a built in clean look (ie no big speakers/wires/ect laying around).

I was lucky to find some Axiom speakers designed to be put into a cabinet, but no one really recommends you put the sub in a box as it really emits sound in all directions from the enclosure, not just the woofer up front. And I've done a dry fit of the bottom cabinets (see http://picasaweb.google.com/rprice54/EntertainmentCenter# ) and sure enough, the bass output that once rattled the house now sucks.

So I'm thinking of using some drawer slides to pull the bad boy out when I want to watch a movie or listen to music, but slide it back in when causually watching TV, kids are around, etc. I have little kids running around, and I really don't want to pull the sub out where they can poke at the driver and mess with the knobs on the back.

If you're still reading, what I'm looking for are some solid full extension slides that won't rattle. The sub is 18" deep, it weighs 75 lbs, and the cabinet it's in is 26" deep, so I'm thinking 24" slides will get the beast all the way out and then some. Right now I'm considering these: http://www.rockler.com/product.cfm?page=21480

Blum seems to have a good rep, I've been happy with Rockler Top Slide in the past, but I've also heard of some slides with polymer bearings that might be quieter. Any other ideas? Anyone tried to do something like this?

[Frank Warta]

I know this isn't exactly on topic but it does kind of relate to what you're trying to accomplish. It's been quite a few years since I was in the sound reinforcement business but as I recall you get +3db gain for each "solid" surface that borders a sub. So by isolating the sub on a shelf, even (and maybe even more so) one that pulls out you're drastically limiting the bass output.

Ideally you want your sub as "close" to the ground as possible, next to a wall is better in a corner is best as far as volume is concerned. It does tend to get a bit muddier since those surfaces aren't generally tuned or tunable but again just accounting for feeling the bass here. So depending on how your cabinet is designed if it's elevating the sub off the floor on a shelf that is likely to be a big part of the lost oomph.

So I would start by trying to get the sub on the floor, close to a wall, and best of all near a corner. I get that you want it hidden but you may be able to do both, again depending on how your cabinet is designed. Good luck!

[Van Huskey]

First, I must say I am acoustically horrified by any alternative I can think of using your basic idea, though from an aesthetic and mechanical POV it makes sense.

Second, have you determined where the sub "want" to be? Although corner loading is the first option your room nodes may mean that the sub needs to be somewhere else to begin with.

Third, my first inclination would be to scrap the sub and build and infinate baffle and make it truely disappear but in a basement that could be hard or very easy depending on the space around the basement. Next I would look at building an enclosure BELOW the cabinetry and putting in one two or three front firing woofers which correctly built could be massively entertaining. Next I would consider building a cabinet as a piece of furniture that could get the woofer where it should be in relation to the room and your viewing position. If you keep the sub (is it an EP 175?) you might try disguising it, you might be able to find a place in a different part of the room that works for your viewing position and allows you to mask the looks without killing performance.

If you do set up the sub to move in and out make sure you have a way to lock it in place when it is out. There is a lot of energy in a sub and it will rattle the heck out of what you put it on/in if it is able to decouple.

[Rob Price]

It is what it is. The room is not just a theater, it's also a living/family/bonus room and I don't want the speaker out in space. It's an Axiom EP500. This is how I need to make it work right now. I may add a second sub in the back of the room down the road.

Again, if I leave it out in the room, little fingers are going to tear it up. I did the sub crawl deal, and believe it or not, the front and center was the best spot for me. The shelf will only be 3" off the floor.

I know it's not acoustically perfect, but it's what I have to work with. I've spent the dough on the sub, so I need to make it work.

As far as movement is concerned, the shelf will be a double ply of MDF with a solid wood tray around the edges to keep it in place. It doesn't move around at all right now sitting on the cabinet base right now (2x4 frame, topped with MDF, filled with sand).

But to the topic, any slide suggestions?

[Glenn Vaughn]

I bought 10 sets of the "ecxonomy" sides from WoodWorkers hardware. They are 100 lb instead of 229 lb but cost 1/5th the price. The are solid and no play. http://wwhardware.com/catalog.cfm?GroupID=Cabinet%20Drawer%20Slides&CatID=Drawer%20Slides%2C%20Full%20Extension%20Ball %20Bearing&SubCatID=Economy%20Full%20Extension

[Larry Rasmussen]

First one was in the attic with the face pointing down ceiling flush. Have done a cabinet or two as well. I happened to buy a couple of really heavy duty slides at Rockler at the close out area a while ago. They are made to be used as file cabinet drawer slides. I just now walked out and grabbed one and shook the heck out of it. Didn't manage to raise a squeek or rattle. However I bet this will be individual to the slide you get and not really predictable by type of bearing.

A couple things about your plan- how bombproof are you going to make those two cabinet walls the slides are attached to? I'd be more concerned about the cabinet rattling than the slides. There could also be a negative effect on sound quality from your equipment being vibrated by the sub, kind of like setting your DVD player, processor or whatever right on the darn thing.

Also once slid out I would want to have something going from the front bottom to floor to take the front weight. Maybe something simple like a maple block you could slide under the front would provide just the right amount of support.

More general comments: If I were faced with this I'd go over to the Velodyne web site and take a look at the in wall or in ceiling subs. I have used their room equalization gear for their free standinig subs and think their set ups for equalizaion are a great value. I seem to remember equalization being available as part of the amps or stand alone but working with the in wall sub amp which would sit separately in the cabinet with your gear.

And finally- if the sub fits right in to the cabinet it can sound great. I heard a demo of a Theil home theater set up playing Pearl Harbor at an audio dealer. Really the most dynamic incredible bass I've heard including theaters when those planes flew from one end of the picture to the other. There were two subs in the 8 foot cabinet the monitor was set up on. There was a clear grill cloth so the doors could remail closed. The subs were smaller Vandersteens, they may still make them. Front firing and optimal for in cabinet use, a different design than their big guys that won them a lot of acclaim. This has been probably a dozen years but take a look at Vandersteen, some stuff doesn't change much in their line so there may be a similar item you could just take a look at.

Got food for thought? Hope so it's late and I'm just free styling some ideas.

Best regards,
Larry Rasmussen- Seattle

[Paul Atkins]

How about wireless earphones? Crank 'em as loud as you can stand and no one will even know. Space saving and you can be anywhere in the area and still get good sound. Yeah, dumb idea, but sometimes you have to think 'outside the box'. Another idea is to put the sub in the footstool and it can be right there.

[Joe Chritz]

Any full extension ball bearing slide should serve you fine.

I use the economy version from Custom service hardware and they hold all of the weight they are rated for.

They also offer heavier slides if you are concerned about that. A 100 pound slide should be fine for what you need. I have 33" wide pantry drawers nearly full of soup cans and they operate with one hand easy.

Joe

[Peter Quinn]

I have a vision of a pullout shelf on casters rather than drawer slides. Something that docks seamlessly into the cabinet but can be rolled out into the room as required but is not physically connected to the cabinet. Perhaps some type of magnetic catch could keep it docked when not pulled out?

[Dan Chouinard]

You have boxed yourself into a corner here but try using some prop legs to support shelf when extended. This will help support and isolate shelf by transfering weight directly to the carpet which sits on concrete. To further isolate sub from cabinetry get yourself some Owens Corning 705. Its ridgid insulation that works fantastically for isolation. Cut a piece of 2" thick 705 the size of your shelf, wrap in fabric for wife approval and set sub without the spikes on 705. Store prop legs in cabinet with sub.

When you want to watch a movie or crank some music just pull sub out, prop legs, turn up and enjoy!

[Karl Brogger]

When I do entertainment centers with a spot for a sub, I generally don't put a bottom in that opening, and I use a cloth pannelled door. Its not ideal, but its about the best you can do if it has to be in a cabinet.

[Derek Gilmer]

Does this room back up to an open closet or attic you can use. If so research infinite baffle subs. I've got one and LOVE the sound and my wife loves the fact I don't have big sub boxes anymore.

[Rob Price]

The base is filled with 700lbs of sand, capped with MDF, and solid, so right now, the sub is essentially on the floor. I can put my hand on the MDF 6" away and I don't get any vibrations- so I feel I have good decoupling from the base. The cabinets on either side will also have a sheet of 30lb felt between them and the base to further isolate them. They won't be physically connected to the sub in any way. I will screw supports for the glides directly into the base.

It's not actually in a cabinet, it just sits between the two cabinets. I extended the face frames one either side, and I plan on using a speaker cloth covered panel for the front and for the top of the sub area, to let as much sound out as possible for every day use.

I do get some bass from it as it is now. There's just a definite frequency loss as opposed to when it was just sitting on the base with no cabinets around it. I want to get as much as I can from it when it's time for a good movie. I will pull it out next time I get and make sure it sounds good from there. I haven't installed any cabinets yet, so I can tweak it if I have to. If I'm not satisfied at all, I do have conduit run to the back of the room for future 7.1 surround, I could always sneak an RCA cable back there and put the sub in the back of the room, but then I have to deal with corner loading, etc. I'm not looking for boomy loud bass- the current spot gets me smooth, even, punchy visceral bass. You feel the gunshots.

I do plan on some type of flip down leg to support the shelf. I found some "shelf" slides that are rated for 100 lbs and since this will be a shelf I will try those. Plus they are black which will help match the dark stain I'm putting on the mahogany. Wish me luck.

[Rob Price]

It's a basement, slab floor, concrete walls along the front, bordered by other rooms on the sides. The back is an open kitchenette area with a cased opening and window. I spent a good deal of time and money trying to insulate the room from the rest of the house. I am having to build a pull out AV rack to fit in the cabinet as well because there wasn't any closet room for the AV rack. I'm trying to make do with what I have.

This is sounding more like a thread over at AVSforums than WW'ing...

[Jay Maiers]

How about going low-tech? Would a simple sliding platform / sled work instead of drawer slides? With the proper nylon or teflon feet installed on the bottom of the platform, I'd think it would slide out pretty easily.

I understand the desire for drawer slides; it would be a little more user friendly and a nicer install. However, I'd be concerned that the low-frequency vibration would get to the slides after a while.

ETA: rockler used to have some heavy duty pantry slides. I bought a set and loaded them down; they were more than capable of supporting 4 shelves of double stacked canned goods. I think I've got another set at home and would be happy to look for them (and the product number) if it will help.

[Rob Price]

lo-tech? hmmm, haven't thought of that. I'll have to chew on it. Where's the fun in that though? :D

I would need some type of guides to keep it in line...

[Jay Maiers]

lo-tech? hmmm, haven't thought of that. I'll have to chew on it. Where's the fun in that though? :D

I would need some type of guides to keep it in line...

Lol! Yeah, I'm with you there. Maybe you could work in a couple of gas struts, or maybe an electric linear actuator... :)

Re: Guides Perhaps some teflon tape or some other slick plasic on the sides of the sled would keep it from marring the rest of the install? I'm thinking that isolation will help prevent rattles.

[Rob Price]

Okay, now this is officially an audio thread...

I went down and played with placement, pulled out, etc. I think I found two problems.

1) the cabinets just change the shape of the room. No matter where I put the sub, the same frequencies have problems. Unfortunately the cabinets make the room almost square. Also, the cabinets are just open boxes right now, when I put doors on them it's going to change again.

2) the sub was behind the overlaying face frame of the cabinets on either side, I pulled it forward so the cabinet of the sub was flush with the face frames and it was like pulling the blanket off the sub. I got the woofer out in front and it came back to life.

I did increase the AVR output to the sub from -5db to 0db, left the gain knob on the sub as is (50%), and set the crossover on my fronts from 80hz to 70hz and I'm back in business. I still have some frequency issues, but I think it's room shape issues now. But I can hear every frequency again and the drums have their punch again. I did notice that if I move my couch up just a hair I gain a lot more bass- room mechanics again.

So I'm going to leave the slide issue alone until I have the cabinets finished, and installed, and then do the whole sub crawl deal again and see if the sub can live where it is or if it needs to go somewhere else.

Thanks for the thoughts though.

[Joe Wiliams]

This is sounding more like a thread over at AVSforums than WW'ing...
Great forum! They helped me spend a bunch of money last year...:p Learned alot too:)

[Mark P. Miller]

I'm not an A/V guy at all, but I always thought that this project was a great way to work a subwoofer into a room.

http://www.sawmillcreek.org/showthread.php?t=122541&highlight=subwoofer+table

-Mark

[Rob Price]

between those (avsforum) forums and these I'm going broke!!!

I like the table. I've seen some guys build stuff around tables, and this thing is large enough, I could put some coasters on top and call it good- it's those little fingers I keep worrying about. The sub almost took a Wii sword today.

[Scott Stafford]

Hello Rob,

A couple things to consider. The subwoofer was designed to be placed on the floor. The woofer and port distance off of the floor affect its performance. Also the woofer being very securely anchored to the floor prevents any motion that might cause unwanted wave cancellations or summing.

If I were to integrate the sub into your design I would leave the bottom of the subwoofer enclosure open so that the sub would indeed sit on the room floor and not touch any of the cabinet side walls. You could still use a grill. Doing this would couple your woofer to the floor and prevent any unwanted vibrations. A subwoofer mounted on a slide out shelf will vibrate and move causing sound derogation. At the frequencies that the sub operates, your entertainment center isn't going to prevent energy from reaching your room.

Good luck!

Scott in Montana

[Greg Portland]

Unfortunately you have a front-firing subwoofer.... this is the least ideal situation with small children. Here are the solutions that I considered when I had to protect my subs from prying hands / toys stuffed into ports. The goal is to couple the driver to a large mass so the subwoofer does not move. Most subs use feet or spikes to accomplish this. Heavier subs already have a lot of mass and their weight alone does a good job of coupling the enclosure to the floor.

Your options (most of which are not going to be ideal for you):

1) Sell the sub and build an IB (infinite baffle). The best performing, cheapest option... except you'll need to put a permanent hole into a wall, floor, or ceiling.
2) Mount the sub to the ceiling corner with some form of heavy duty shelf (yes, I know how big it is). You'll still get the benefits of corner loading by doing this & the kid can't reach it. Be sure to bolt the sub onto the shelf! IMO this is your best option if you must stick with your current subwoofer, assuming a certain level of wife acceptance.
3) Build a table subwoofer as shown in previous posts (you can reuse the components). You could also sell your current sub and build something from scratch (it's not that hard).
4) Build some form of plate or solid covering for the entire front of the sub. When you want to use your system, pull off the plate. Place the subwoofer in the optimal location based on your measurements. Make sure the driver won't hit the plate if you forget to uncover it before a movie.
5) Front projection system with acoustically transparent screen; place speakers behind the screen.
6) Stick the sub in the cabinet and live with the less than optimal sound quality.


No matter where I put the sub, the same frequencies have problems.You will probably need a parametric EQ, regardless of where you place the sub. The idea is to place it in a location with minimal problems so you can reduce the number of filters. 3 filters (one for each room mode) is the likely result for most good placements.