Sub suggestion, DIY or store bought (1 Viewer)

[Eric Kahn]

I have my HT set up in a 14' by 15' by 9' high room

I would like a powered sub that will handle down to 20 cycles and below for movie use but would like to keep it below $500 due to limited budget, size is really not a factor but it will have to sit next to the TV so shielding is an issue

I use Chorus II's as my main speakers, found out they do not handle the lows in Star wars, TPM pod race scene very well at all, so now the great sub hunt is on

I most likly will not be using this sub to listen to stereo music, the Klipsch Chorus II's are great for that

thanks for any help or suggestions

I have built speakers before, but from exact plans, I do not know what the numbers mean that are in the specs for bare drivers

 

[Vince Bray]

You mention TPM, so I'll assume you want very deep, very loud bass. The loudness (spl - sound pressure level) is directly related to the displacement capability of the woofer, just like a car engine. Bore x stroke is it. The working surface area (sd)of the woofer is the bore, and the linear maximum travel of the cone one way (xmax) is the stroke. You need as much of both as you can afford.
Do you have a size restriction? If a cylinder would work, the sonosub is likely the best solution. It allows you plenty of volume to tune the driver nice and low.
One sonosub = adire tempest driver + 250 watt plate amp.
Roll in big tube and serve loud.
http://www.adireaudio.com/cd/tempest.htm
http://www.partsexpress.com/pe/showd...15985&CATID=43
Here's a great example:
Link Removed
This is not a tempest, but similar. 250 watts would get you to 110db +/- 1db from 30hz up. -3db at 20hz with a tuning of 18hz. This is one of the best bang/buck ratios going. You could get more spl capability but it'll cost 'ya. The blueprint drivers will perform even better, but the amp will take you over budget. You could easily build the sonosub for:
driver: $140
amp: $140 from parts express (think it's still on sale)
cabinet: $200 generous allowance with full veneer.
You could build this to look alot like the new svs with some nice veneer...
http://www.svsubwoofers.com/SSpics.htm
Vince

 

[SalMaglie]

It's not really that hard to build your own sub. I just finished my first one...well I built one but didn't put a finish on it cause I'm going to build a different cabinet. The poster above is recommending a good setup, but I went with the Shiva instead of the Tempest, which is the same combo offered to a lot of us newbies just getting into the DIY sub building hobby. Either way though you can't go wrong. I went ahead and stuck with the plans on the Adire site and built a 54 liter, Q=.707 enclosed cabinet. Making the cabinet was straight forward, but then I already had the woodworking tools. All told, i guess I have a little less than $300 into it, and my sub sounds better than I thought it would. The wife was skeptical about this purchase, but once I threw in Phantom Menace in the DVD player and hit the pod race scene, she was all smiles.

One thing I did that's recommended for that Parts Express plate amp was to defeat the 30hz bass boost that's built in. Eric at Parts Express even sent me for free the 2 resistors that you need to swap out to defeat the boost, and if you get one, you might want to send that request along with your order. All you need to fix the amp is about a 20 watt soldering iron, some solder, and a desoldering tool like a little bulb pump helps.

For my next cabinet, I think I'll try a SBB4 ported cabinet since most of my music listening doesn't involve deep bass, but most of my movie watching does. Now if I can just find that perfect veneer to go with it.

 

[Eric Kahn]

where could I find the plans for this

a cylinder is not a problem

Is this based on a concrete construction tube?

since I live about 40 miles from springboro, going to patrsexpress for parts is easy for me

Thnaks for you answer

 

[SalMaglie]

There's a link at the front page for this DIY and advanced HT topics area. If you can't find it just go to this page:
http://members.tripod.com/~terrycthe...um/page12.html

 

[ThomasW]

STOP this thread for just a minute!

Eric said he needed a SHIELDED driver.

BluePrint, SVS, Tempest, Shiva, etc, etc are not shielded. I certainly don't know of any DIY high performance woofers that are shielded.

So before wasting more bandwidth on this sub, someone better locate a shielded woofer, or Eric needs to rethink his project

 

[SalMaglie]

Boy it's a good thing somebody around here is directing traffic for us poor slobs who can't read.:b

 

[Eric Kahn]

I think the sonotube design would be perfect for me.

On the sheilded driver issue I put in, I read in another place about ''bucking magnets'' put on the back of unshielded speakers to nullify their influence on the TV

they were speaking of a pair of old Klipsch speakers in this case, I wonder if this could be done to the tempest driver mentioned above as everyone so far thinks the Shiva and tempest are great drivers ( I have not heard either but I am new)

if all else fails, it can sit on the other side of the room by the couch, not the most ideal solution though

Thanks for all the imput so far, I am going to go up tommorow (today now) and buy the plate amp from parts express

 

[Ruben Zamora]

partsexpress has a 10" SHeilded subwoofer.

 

[Dave Poehlman]

I'd like to interrupt this thread to insert my $.02...

On the sheilded driver issue I put in, I read in another place about ''bucking magnets'' put on the back of unshielded speakers to nullify their influence on the TV

I haven't been able to find bucking magnets big enough for a sub. Let me know if you find any.

Also, the magnets you will be dealing with will be quite large and strong... so, applying them will be difficult.

Now back you your regularly scheduled thread...

 

[ThomasW]

Eric

Adding bucking magnets, using Mu-metal, lining the enclosure with sheet metal, are not as effective as factory made shielded designs. This is especially true if the sub must sit right beside the TV

But if you can live with the other placement option, you can get a great sub, at a great price by using the DIY designs people are talking about here.

But if a shielded design is necessary, you won't find find a driver available for DIY'ers that has the performance of the units talked about here.

 

[Scott Simonian]

What kind of television do you have Eric? Is it a direct view or a RPTV? How close does the sub [rant]really[/rant] need to be to your tele?
If it is a couple feet away, you shouldnt have a single problem with interference problems. All the speakers in my system are un-shielded, including my sub. I even have a un-shielded center speaker sitting right on my tele and I dont have any problems. Well, it is a RPTV.

 

[SalMaglie]

This shielded sub issue got me to wondering too. Most TVs are at least a couple of feet off the floor, and since the sonosub typically has it's driver placed in a downfiring position at the bottom of the tube, does it actually cause problems when placed next to an elevated TV? Maybe some of the veterans can chime in who've tried this placement.

 

[Jack De La Vega]

Eric,
You can buy magnets from local distributors, look in the yellow pages under magnets. If you dont find a distributor in your area call Miami Magnet Co. 1-800-222-7846 they have any size magnet that you can think of. To mount the magnet you can use Devcon 5 minute epoxy that can be bought at your local hardware store. I have built several center channel speakers and used bucking magnets and have never had any problems with the TV. Have fun with your project.
Jack De La Vega

 

[Scott Simonian]

Ah, Sal brought up another thought.

How high off the ground is your TV? If you were to make a "sonotube" based sub, the driver would be low to the ground.

I honestly think you arent going to have any problems with your TV. In my bedroom I have un-shielded PC speakers and they are right on the sides of the moniter. No problems.

 

[Patrick Sun]

Yeah, for most bottom firing sub-driver configuration, the driver will be no more than 12-18 inches off the ground (usually the sub will be 4"-6" off the ground. Most TVs will be 24"-36" off the ground if not further away.

 

[jeff lam]

Isn't the HSU VTF2 shielded? I thought I read somewhere that it was. Anyway, it is the best $500 powered sub out there according to Tom V.(of SVS) in several posts regarding subs in the hardware section. You will have to double check on the shielding part though. As everyone around here knows, if Tom V. recommends it, its an awesome sub!!!

Give it a look.

Otherwise go with the sonosub. just make sure the driver is at least 2 ft from the picture tube.

 

[Eric Kahn]

Thanks for the answers

while I was at parts Express this morning to buy the amp

I saw one of their sub kits using the amp and the new Dayton DVC 15 inch driver and bought it

3 cu ft sealed box comes with it made out of 1 inch MDF and braced with 1 inch MDF

it Took me about 3 hours to put it together (they say 1 hour) and I have just discovered one of the limitations of my Yamaha 5150 reciever, you can not adjust the sub crossover frequency

you can tell it that you have large mains and it will send the bass signal to both the mains and the Sub or you can tell it you have small mains at which time it will cross over the bass to the sub at 90 Hz

I guess next year I will be in the market for a new reciever that can address this issue

I might have to try telling the reciever I have small mains and adjust the subs crossover to about 90 and see what happens when I Play the Pod race scene again

I had to put the sub box about 18 inches away from the TV stand (32 inch sony) to keep it from affecting the screen, I guess the sony is more sensitive to magnets than some

sub box is sitting on the floor and is front fireing

If I do not like this box, I can always use the amp and driver in a sonotube sub later once I figure out what I am doing with the adjustments

how do you tell if you have a standing wave problem in a sub?

 

[Vince Bray]

Thanks, Thomas. That was sloppy. :b Me too.

Subs have more effect on the tv than other speakers. While working on the HE15, I walked past the computer at about 3-4' and the screen bowed in extremely noticeably. It turned purple, green and looked funky. Amazing how the effect is totally based on magnet mass. I would think two feet enough for the tempest or DVC, and getting the sub magnet out of the plane of the tv seems to help alot. i.e. a line extended across the diameter of the magnet should be above or below the tv, not pointing right at the screen. This seems to give a little more leeway.

How cool is it that you can ride to PE? How is your sub sounding?

Vince

 

[Eric Kahn]

I am sure my tennant upstairs is well aware that I have a Sub hooked to my stereo, I set the Level control at halfway as a starting point and ran the Pod race on TPM and was rattleing the walls, I had to turn it dowm twice to get it to a level that seemed to match the main speakers

I will have to play some other movies to see if I have it set right

I also will have to try the Small main setting and route all the bass below 90 Hz to the sup during a movie to see how that works also since I have overlap between the sub and the mains right now, receiver does not have enought adjustments to take care of this

I had never been to parts Express or bought anything from them untill now, they have lots of cool stuff