Another small subwoofer thread.

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I moved into a condo a few years ago and I've been subwooferless the whole time. I came across the Totem Dreamcatcher one day.

http://www.totemacoustic.com/english/products/subwoofer_dreamcatcher.htm

I had a listen to it and decided it was perfect. It's sounds great, is very small (w 7.75 x d 10.75 x h 10.25”) and perfect for my tiny living room. Also as a major bonus, it has very high WAF. Then I asked about the price. $850 Canadian.

I decided it was time to get back into DIY. My current 5.1 (minus the .1) is all DIY MTM's that I built about 5-6 years ago.

I'm looking at building something based on the TB W8-740C. I find the occasional mention of it, but I can't find any plans or pictures of completed projects. If someone can point me in the right direction for success stories with this driver or something similar, that would be great. I want to keep the box as small as possible.

Apparently Audioxpress had an issue with a design for this driver. I can't find it listed in the back issues on their site. Anyone know what month that was?
 
That sub looks like it won't add anything your mains can't do already, assuming some typical 6.5" midbass drivers in them.

There are a gazillion sub examples out there, but if you have strict WAF requirements, they selection is smaller. In that case it's not difficult to design from scratch. Just get WinISD pro and start modelling drivers ...

A few WAF ideas:

* IB subwoofer if you own your own place
* a conventional sub with a 12" driver in something made to look like conventional furniture ie. a coffee table, or a chest of draws that is really a sub
* put it in a corner and make it a slim rectangle - ie 13" x 8" foot print and it can be tall to make up the required volume
 
Thanks for all the suggestions. I've done the "coffee table/foot stool subwoofer" before but I had trouble hiding the wires good enough.

It won't take much of a subwoofer to add to my system. My current mains and center have just 4" mids.

http://coquet.info/ht/tower1.jpg
http://coquet.info/ht/tower2.jpg

The Adire Extremis looks very interesting:

"Our favorite application: 21 liters, tuned to 33 Hz with a 2" flared port of 8" length. Clean and flat anechoic response to 35 Hz, and in-room extension to the low 20s."

Time to start playing with WinISD.
 
Konnichiwa,

diydave said:
I'm looking at building something based on the TB W8-740C. I find the occasional mention of it, but I can't find any plans or pictures of completed projects. If someone can point me in the right direction for success stories with this driver or something similar, that would be great. I want to keep the box as small as possible.

I would recommed to consider for a really small sub the ApexJr Super Sub 8" Woofer and a suitable matching Amp from ApexJr:

http://www.apexjr.com/SuperSub.htm

http://www.apexjr.com/ApexJunior.htm

You do need to equalise the SuperSub when used in a small sealed enclosure, the Apexjr Plate Amp is easily changed for that.

The Supersub & Amp caertainly exceed the REL Quake Sub in performance and build quality is very high. The Subamp includes a cover, so no seperate airtight section is needed for the Ampp.

Sayonara
 
Re: Re: Another small subwoofer thread.

Kuei Yang Wang said:
I would recommed to consider for a really small sub the ApexJr Super Sub 8" Woofer

Why do you recommend this subwoofer? It's crap IMHO, a Dayton from PartsExpress look significantly better, and the Extremis is several classes higher...

I'm missing something I guess.
 
Re: Re: Re: Another small subwoofer thread.

Konnichiwa,

simon5 said:
Why do you recommend this subwoofer?

Because the original poster seemed to ask for an affordable solution and seemed to desire a form factor similar to the Totem Sub. I have some experience with the ApexJr Driver and it is rather several cuts above what most semi-affordable commercial subwoofers fit.

simon5 said:
It's crap IMHO, a Dayton from PartsExpress look significantly better, and the Extremis is several classes higher...

I am not sure which Dayton 8" Subwoofer driver you refer to or what looks have to do with it.

True, the extremis is better on paper (never heard it) but is it worth 2 & 1/2 times the price, in the application?

At any extent, my suggestion overall costs $ 130 US plus shipping and wood and works well together, making for a cheap and capable small sub....

What is your problem with that?

Sayonara
 
DAYTON DC200-8 8" CLASSIC WOOFER
Same excursion for 20$, way lower Fs.

DAYTON SD215-8-8 8" SHIELDED DVC SUBWOOFER
More excursion for 23$, way lower Fs.

DAYTON RS225S-8 8" REFERENCE SERIES SHIELDED WOOFER
Even more excursion for 43$, way lower Fs.

DAYTON 8" QUATRO SERIES SUBWOOFER 4 OHM
Two times the excursion for 49$, lower Fs.

Sorry, I was talking about what the driver look on paper (specs), not "visual" look, I don't care about that at all.

It's affordable, you're right, but a subwoofer with less than 5 mm Xmax scares the hell out of me. The ApexJr amplifier is a nice solution, I'd pair it with another woofer that's it. 140$ + shipping with the Dayton Quattro, better I guess.
 
A little OT but are those Whamodynes you built? And if so, did you ever build the matching BP subs?

Yes! Those are Whamodynes (with a few tweaks). I did not build the matching subwoofers. I had a previously built a subwoofer using a 15" Madisound sub, so I opted not to build them. Unfortunately, the 15" sub is huge and not condusive to condo life so I gave it away. :dead:

The Apex Junior sub looks interesting too and it's only $40 US.
 
put it in a corner and make it a slim rectangle - ie 13" x 8" foot print and it can be tall to make up the required volume

Here is a classic single-fold straight transmission line design for the ApexJr 8" woofer -- tuned to 34 hz.

I used Rick Shultz' AlphaTL calcs (in the XLS that GM posted).

Driver: ApexJr 8" woofer (approx $50 shipped)
Qts: .51
Vas: .38 cu ft
Fs: 48 hz
Fb: 34 hz
Fibreglass stuffing: 1/2 lbs per cu ft

Transmission Line (two -- single fold) inner dimensions (each):
Width: 8"
Depth: 3.75"
Height: 41"

Enclosure outer dimensions:
Width: 9.5"
Height: 50"
Depth: 9.75"

Driver placement: top of the enclosure (no offset)
Terminus Placement: directly below driver (4" x 8")
Ideal enclosure placement: mid-wall (vs. corner)

I have had great success with Apex Jr (Planet10 introduced me)

Also, I have learned much from Kuei Yang Wang's prolific posts on this forum (thanks), and would be hard-pressed to go against a recommendation of his...

Regards
Joe
 
Konnichiwa,

simon5 said:
DAYTON DC200-8 8" CLASSIC WOOFER
Same excursion for 20$, way lower Fs.

DAYTON SD215-8-8 8" SHIELDED DVC SUBWOOFER
More excursion for 23$, way lower Fs.

DAYTON RS225S-8 8" REFERENCE SERIES SHIELDED WOOFER
Even more excursion for 43$, way lower Fs.

DAYTON 8" QUATRO SERIES SUBWOOFER 4 OHM
Two times the excursion for 49$, lower Fs.

Both excursion and Fs are only relatively relevant in the application, Xmax more so, but even there the failure to have really consistent ratings leave much open to abuse.

simon5 said:
Sorry, I was talking about what the driver look on paper (specs), not "visual" look, I don't care about that at all.

Okay, but be aware that paper is patient.

simon5 said:
It's affordable, you're right, but a subwoofer with less than 5 mm Xmax scares the hell out of me.

Why? If applied in a compact (say 10" cube or around 8 Liter once driver and amplifier displaced air are accounted for) enclosure the driver can handle still well above 200W @ 20Hz before running out of Xmax.

You seem to be bent on advertising specs without any reference to the actual application.

The Driver from Apex has an extremely strudy build to withstand the forces developed in small enclosures and it's construction is aimed at exactly that kind of application.

In such a small box the driver will manage in room, pushed into a corner and with the recommended Apex Amp you get 80db/2.83V/1m (or around 100db/1m max power @ 30Hz ) which is not bad at all for such a small system.

With a first order lowpass at 30Hz looped in after the speaker feed to the main speakers and the signal fed to the line level inputs in room you should get around 35Hz - 120Hz +/-3db frequency response without including room modes.

In the interrest of making best use of room acoustics I personally would recommend two of these subs, in the respective left & right room corners of the front of the room. That is invaraibly superior to one sub, even a much superior one.

Anyway, that is my reasoning. And as said, something like that works rather well.

Sayonara
 
From the webpage for the Apex Jr subwoofer it looks as though they are calculating Xmax by looking at the thickness of the top plate. Is this an accurate way of figuring Xmax? It would seem to me that it is more dependant on the voice coil length than the top plate thickness. The driver just looks like its capable of quite a bit more.

and an Le of 0.157mH? That can't be right.
 
Konnichiwa,

DcibeL said:
From the webpage for the Apex Jr subwoofer it looks as though they are calculating Xmax by looking at the thickness of the top plate. Is this an accurate way of figuring Xmax?

No, it is an extremely conservative way of reckoning. High Xmax drivers are often rated using other methodes (Dumax comes to mind) which give a considerably larger Xmax.

DcibeL said:
and an Le of 0.157mH? That can't be right.

The extremis claims 0.13mH for a 4 Layer Voicecoil, so it is at least possible. If the driver uses measures to control voice coil inductance and thus to improve linearity 0,16mH is possible. But it may very well be a misprint.

Sayonara
 
Did someone say "small DIY sub"?

I built this for use with some Optimus mini-speakers powered by a receiver providing audio for my computer. It uses a Dayton Classic 6 1/2" woofer and a Dayton 8" passive radiator and powered by a subwoofer plate amp. It's super easy to make and has alot more thump than you'd guess. Smaller than most any other 8" driver sub (easily hidden) and for the price (about $40, plus amp), hard to beat. For HT, you could even use 2 (8-ohm version available), get better coverage and still not break the bank. Here's some construction details.
http://nate-diggidy.smugmug.com/gallery/528207/1/22372112]Project Bitty-Boom[/URL]

How you finish for SAF is strictly up to you ;)
 

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How big are your main MTM's?

I have a pair of extremis6 midwoofers myself and to use them for just subs would be a shame. They have great midrange and can easily be used up to 2khz.

I'd suggest just rebuilding your L and R channels with some 1cube(or less) 30hz tuned extremises. You could then cross those over possibly to the M's and T's you already have and end up with a 3way main good down to 30hz(and below in room)
 
Apex Jr 8" Acoustic Cannon Tower

Here is another idea.

It has a small footprint (approx 8 1/2" x 11").

It is 56" high.

It is tuined to 24 Hz -- 1/2 the driver's Fs.

The attached pic shows the interior / exterior.

The long line (~141") is comprised of three folded lines (8" x 2.3" x 47" interior).

The short line is 8" x 2.3" x 47" interior.

It is small because the cross sectional area of each line is 1/2 the SD of the driver.
 

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Bitty-Boom link

Here's the proper link for the photo gallery of the small sub I posted above.

http://nate-diggidy.smugmug.com/gallery/528207

I dare ya' to come up with an easier to build sub ;) . This thing is so easy, the passive radiator dosen't even need any additional weight to tune it. Parts Express sells vinyl laminate to cover the "tube" part in different finishes and you just paint the end caps to match.
Just place it against a wall and let the laws of physics take over where the drivers leave off :cool: .
 
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