Read Enough To Be Dangerous! Really Need Sub Help. (1 Viewer)

[Martin Rendall]

Greetings,

After a night of searching the forum for DIY sub information, I'm not a bit stumped. I'm a lot stumped.

First, my particulars:

The room is 22' x 24' with cathedral/vaulted ceilings, so about 3000 ft3.

I have a hybrid 2 channel, HT setup. I have a tube preamp with an HT passthough circuit. So what happens is that in the passthough mode, my receiver mains preouts go to the tube preamp (but passthough, so nothing is done to the signal - the preamp doesn't need to be on) and from there to a 2 channel amp, to the speakers. In 2 channel mode, the receiver is bypassed, and the 2 channel source goes to tube preamp, to 2 channel amplifier, and then to the speakers. My CD player is hooked up to the tube preamp, while my SACD player is hooked up to my receiver. Hope that's clear.

So as you can guess, 2 channel music is extremely important to me, but so is multichannel music, and of course, movies. The mains are Paradigm Studio 100's, v2.

I want to optimize them all, and on a budget.

I like the price point of the Tempest.

Due to the square shape of my room, 2 channel is suffering a slight bit. Specifically, there's too much mid-bass bloat for my tastes. My initial thought is to add a sub to crossover with the mains (using a Paradigm X-30, 80Hz, for example), and use a BFD to flatten the bass. So that would indicate a sealed low Q sub.

But for SACD and movies, I need an LFE channel sub; probably a ported sub.

So I think I need 2 subs. One musical sub augmenting the mains, and another HT sub for the LFE channel. And then maybe another BFD for the LFE sub.

But that seems very complicated and expensive.

I just can't make up my mind about which Adire design (yes, I want to stick to the reference designs) would be the best compromise if I went with one sub, and I can't really see how to integrate it into my environment.

The good news is that I don't care how big the sub(s) are. Size is not a concern, as this is a dedicated room, and it's all mine.

To complicate things, I know very little about woodwork. But willing to learn.

All help appreciated!

Thanks,
Martin.

 

[GrahamT]

The Tempest is a good choice and you can find them cheap at www.creativesound.ca . I built the EBS alignment, it is very big and efficient. You can have two subs and use one BFD, it has two channels of EQ, one for each sub. Since this is a dedicated room, have you considered an infinite baffle. Supposedly, it is the most musical sub alignment, and it goes very low and loud with little power.

 

[Martin Rendall]

Graham,

The IB solution looks very nice, but I don't believe I have an appropriate adjacent room to work with. My room is actually a finished loft.

Thanks for the BFD tip... very good to know!

Martin.

 

[Dustin B]

I doubt you could tell the difference between the 0.577Q sealed and EBS Vented with music. I know I couldn't notice a difference between my sub with the port open or closed on music. I could however tell the difference between my sub with the port open and closed on movies with the big low end content.

 

[Dustin B]

Also if you think you could swing the cost of a second Tempest and a slightly more capable amp to power a pair. You could do a some what larger than EBS enclosure with dual Tempests. This would provide plenty of headroom for your room.

A design Dan Wiggins advocated a while ago was a 480L enclosure stuffed with 8lbs of polyfill tuned to 18hz with a pair of 6" straight ports and two Tempest drivers.

 

[Brian Fellmeth]

Yes, do this. A large sealed tempest with a BFD makes an outstanding HT sub as well as a great music sub. My BFDed sealed tempest will shake the room as well as any ported unit of similar caliber- the BFD can compensate for the sealed roll off effect as well if not better than a port- and it doesn't die a sudden death just below the tuning frequency. With a powerful amp for the sub you can have it all. Output of X-30 to one channel of the BFD. Output of the "sub out" of the HT receiver to the other channel of the BFD for movies, SACD etc. Of course, the BFD programs will be a little different for these 2 signal paths.

 

[Martin Rendall]

Brian,

I'm intrigued with your suggestion. So X-30 to one channel of BFD, and receiver LFE to the other channel. Are you suggesting that I somehow combine the two BFD output channels to one sub after? How would I accomplish this? The plate amp has two inputs I guess. What happens with the sub when there's sometimes only signal on one channel?

Thanks,
Martin.

 

[Ryan Schnacke]

Most plate amps sum the two input signals internally. So it should work just the way you're thinking.

Another option (as if you didn't have enough) is to build the Adire ported alignment and make a port plug to use for music. This is a little more hassle since you have to actually walk over to the sub and plug/unplug the port as opposed to Brian's idea where the switchover might happen at the push of a button on your remote.

 

[Martin Rendall]

Nice. So my plan is to build a sealed Bessel alignment box (230L), with a Tempest, 250W plate amp, and get a BFD and an X-30.

Scoped out Home Depot. Saw some nice flat 24" X 48" 3/4" MDF. Now, what sort of tools do I need to cut the wood? Do I need to buy a table saw, or can I make do with something cheaper? Also, how the heck do I cut out the circles? I have a Dremel if that helps.

Are there any REALLY beginner guides which could help me get up to speed?

Thanks,
Martin.

 

[Ryan Schnacke]

A hand held circular saw can be used to cut the MDF if you build a saw-board to help you cut straight and accurately. Search for saw board on the web and you should be able to find some instructions for building and using them.

Dremel is generally not recommended for cutting 3/4 MDF. It can be done, but would take many passes with a small depth of cut. Most guys use a router and a circle jig (homemade or store bought).

In this case you're not going to be flush-mounting the woofer and its going to be on the bottom of the enclosure. So you don't really need a pretty or perfect circle. If you can use a compass or some other method to draw an accurate circle then you can just use a jig-saw to cut it. This will take a while to do since its 3/4 MDF and you'll want to be fairly accurate. But I know from experience that its not really difficult.

 

[GrahamT]

Yeah I agree with Ryan, router and table saw works best. But a circular saw and jigsaw will work too.

What amp are you thinking of using?

 

[Patrick Sun]

If you don't have a table saw or router, you might want to see if you can source out the MDF panel cuts at local woodshops, or find a friend or friend of a friend with a table saw.

Routers and jigsaws are better choices for the driver cutouts.

 

[Martin Rendall]

Graham,

I was thinking of getting the plate amp from Creative Sound. On the other hand, I may get the JASPER CIRCLE JIG set from Parts Express. If I order from them, then I might get the plate amp from them instead. I need to do some reading.

If I go the plunge router and circle jig route, can anybody recommend a decent cheaper router model? I think I will want to build some speakers in the future, so this isn't necessarily a bad expenditure.

On the other hand, if this project is going to cost too much, I'll just get a Servo-15. At least it will have a decent resale value later on.

Speaking of which, realistically, how would the sealed Bessel alignment with Tempest compare to the Servo-15? I know there a lot of apples to oranges with this question, but I still want some idea.

Thanks,
Martin.

 

[Brian Fellmeth]

Martin,

Since you don't have tools, you might take a look at this from a Canadian company :

Sub kit

It uses the Shiva which is the tempest's little 12 inch brother. Designed with a port that you could plug for music. Does not have an amp, bur you can use any funky stereo receiver from the 70's laying around the house- as long as it has some power will drive it just as well as a "sub amp".

 

[Cam McFarland]

Martin,

You do not need a router for driver cutouts. I jigsaw does nicely as it does not need to be a perfect hole.
If you were going to build a sonosub, I would recomend a router as the endplates for the tube should be perfect.
As far as routers & jigs, I just bought a Sears router that came with a circle cutting jig (up to 24"). It was only like $60.00 & works like a champ.
I had never used a router before I bought this.

I tried cutting straight cuts with a circular saw & could not get it good enough for my taste so I bought a tablesaw.
Again from Sears....10" with dust collector & 24" fence cut width ~$165.00 on sale....greatest thing since sliced
bread, sure saves ALOT of time.

By the way, I built an AA Tempest....love it.

BTW, hole cutters that you attach to drills are a quick way tocut holes in the bracing.

 

[Mitch N]

I'm curious why no one has mentioned the Rythmik Audio servo kit. You could have a low Q setting for the 'tight' bass sound, or a looser Q setting for more boom.

They even have finished enclosures.

 

[Martin Rendall]

Funny you should mention that. I just ran into that last night. Will have to investigate further.

Martin

 

[Dean-P]

If you are going to use the router, get it at Sears and get their circle jig, its only $20. Also a note on mdf, it is heeaavvyy, so a small table saw would be hard to hold it on plus the fence won't open wide enough. Using the circular saw with a clamped on fence to the mdf works best. It takes a little figuring out to where to set the fence at in regards to the saw cut, but I found out that this works best unless you have access to a large table saw. One more thing, the last mdf I used was an actual 3/4" whereas others were metric 22mm, so you will have to compensate your cuts for that. And also my last piece was not square on the ends, so I had to make an intial cut to square it up!
The jigsaw works well for cuts, but be sure to have a sharp blade, this also applies to the circular saw blade.
Solen has some plate amps also and they cost less than the other Canadian comnpany, although CSS does price match when you send him an email. You can also pricematch your port to CSS from this company Genuine Canadian Audio .

 

[Cam McFarland]

I generally have my MDF cut into 2'x4' pices, this way
I can load/unload easier by myself & it makes it easier
to cut on my table saw (Sears $165.00) that will accomodate a 24" cut.

Of course I would not have it cut that size if it wouldnt fit my plans..

 

[Cam McFarland]

Just realized this was untrue.....I also paid ~$20.00 for my jig.....:b