How to make you own subwoofer (1 Viewer)

[LanceJ]

Parts needed:

1 spare speaker

1 spare receiver

1 interconnect

speaker wire

That's it.

To "assemble" it: A/V receiver's subwoofer output ---> unused input on the secondary receiver (not a phono input!) ---> secondary receiver speaker output ---> speaker.

* Sub's gain is adjusted with the secondary receiver's volume control.
* Polarity - 0 or 180 degrees - can be changed by simply reversing the speaker wire at the speaker's input (or secondary receiver's output if that's easier).
* crossover point is adjusted within the A/V receiver.

You're done.

I've been experimenting with my own sub system - see pics below - for more than a year now, made up of my Pioneer SX-6 receiver I bought new in 1983 and a Realistic Nova-8 bookshelf speaker, which uses an oddball-sized eleven inch woofer w/cast aluminum frame in an acoustic suspension enclosure. I bought the Nova, which had no mate, for $5 at a thrift store. Its woofer uses a doped cloth surround and is still fully compliant and the woofer works perfectly. Until they turned into a cell phone and battery store, Rad Shak actually made a lot of decent audio gear until the mid 90s.

Obviously the overall quality of this system will be determined by the speaker used and the power output capability of the receiver. As far as size of the subwoofer is concerned, for most rooms personally I think a speaker with a 10" woofer is the minimum. Dorm rooms (if the R.A. doesn't care) and other typically very small spaces can get away with an 8" woofer.

Volume-level wise, probably the biggest factor that will keep most of these cobbled together subs from competing with normal subs is amplifier power. But watching the SX-6's power meter, while admittedly not ultra accurate, I saw that most of the time in my little 11ftX14ft mancave, it hovered around 5 to 20 watts at normal listening levels i.e. I can still talk to a nearby person without shouting. But if I tried to turn it up to a level that did require shouting, the power output VERY quickly shot up to the 60 watt level but that was after the Nova's woofer cone started noisely banging against its frame.

>>> As far as how my own sub system sounds, I think it sounds just like a "real" sub, probably one going for around $250 in a brick & mortar store but need to clarify that: the sound itself is more on par with a $400 sub, but ultimate volume level is more like a $150 sub - that Nova just wasn't designed for the combined bass output of up to six separate channels of a modern movie's soundtrack!

Another option: you could use TWO speakers for your sub system (plus, supposedly two subs can create a bass soundfield that covers the room with fewer gaps). And if your receiver has a mono button that affects all inputs and not just the FM tuner, there is a good chance you won't even need a splitter to convert the sub output to 2 channels (for input purposes), because usually, pushing the mono button will internally direct that single signal to both channels of the receiver.

Besides just being fun to mess around with, part of the motivation for writing this is the increasingly lousy state of our economy: for example if you have to make a mortgage payment, that can really put a dent in your A/V budget; and if youre a college student you know the frightening cost of tuition/books/etc is making it extremely difficult to afford much else, much less frivolous items like audio gear.

Now you can apply that earth-friendly attitude you keep hearing about to your A/V hobby and recycle that old gear taking up space & irritating your wife/girlfriend/parents!

 

[Robert_J]

Have you plotted the frequency response to see just how low it goes? All it takes is an SPL meter (Radio Shack has the cheapest), test tones (free) and a spreadsheet with the appropriate meter correction values (free). Near field, I bet the F3 is in the 50hz to 60hz range. In room respsonse is probably not much better. Why? The driver you are using is not a sub. It's a woofer. Two different driver types with two different uses.

Enlarge the driver mounting hole to 11". Drop in a Dayton DVC 12". Wire up each voice coil to your Pioneer amp. It won't be a pretty sub but the frequency response will be much better. You will actually get sub bass output.

-Robert

 

[LanceJ]

Oh I know this system doesn't go as low as a purpose-built sub but relatively speaking, it goes much lower and has much more authority than the Boston Acoustics CR9s that were formerly providing the low bass. So I guess you could say this is a "Sub Lite". bwahahaha! sorry! IIRC someone on the Audioholics forum tested the Nova 8 and its 3dB down point was @30Hz. The Bostons' is at 42Hz. And since sealed designs fade out slowly vs. ported designs (the Bostons' 8 inch woofers are ported) I am positive it still has useful bass output below 30Hz.

For example, in the opening sequence of Attack Of The Clones it can reproduce most of the low rumble of the princess' chrome ship as it passes overhead, nearly as well as a buddy's 12" Infinity PS12 subwoofer but definitely not as loudly. Though we can still clearly feel the couch cushions vibrating with the Nova's output, along with the rattling of the glass in the window next to the Nova, again, just not as intensely.

(extreme) music example: on the Linkin Park Reanimation 5.1 dvd-audio, on "1stp Klosr" there is a down-sweeping, very low frequency bass tone that occurs several times. The Nova can reporduce about 80% of it.....then pretty much goes silent. OTOH that PS12 can reproduce the entire sweep with no drop in output at all. Next, playing my Telarc CD of The Firebird Suite, the Nova only does O.K. with the incredibly powerful drums during the crescendo at the end of track 1, but just cannot reproduce them with much authority like the Infinity can (to give these 30 year old vintage speakers a break, even at mid-level volume settings this non-compressed recording can easily bottom out the woofers in many modern large floorstanding speakers).

Otherwise.......for rock/pop music in general the Nova has no problems whatsover. Bass is very smooth and unobtrusive but still can kick when needed, though it has that "velvety" punch which is typical of a sealed design. And none of this is being said with the caveat "for an old speaker it........". With as unbiased an attitude as I can manage, this real walnut finished oldy from the 70s just plain sounds good. Despite today's marketing hype, speaker designers back then DID know a lot of the techniques modern engineers know now.

And it only cost me five bucks!

 

[Robert_J]

You can't beat the price. Use it a as a learning tool though. Save up some money and buy the driver I linked to. It's a great hobby. I've been building speakers since 1987 and I haven't gotten tired of it.

-Robert

 

[JohnRice]

I think it is worth pointing out that running a regular woofer off a LFE output doesn't give any extra bass from what it would produce using it as a regular speaker. You just limit its frequency range more than normal, which might have some benefits, but it won't make all that much difference in bass reproduction. It does let you place it specifically for bass, but as was already pointed out, it is far from a sub. The suggestion of installing an actual sub driver is a decent one though, even if the cabinet isn't designed for sub use.

 

[LanceJ]

I never said anything about using an LFE output to cause a conventional/fullrange loudspeaker to generate more bass than it is actually capable of. But that Nova is placed in a corner and like any bass radiating device, it will produce much more bass there than when placed in the conventional location its original designers were thinking of.

I used to sell HT subs for 3 years, have set up several of them for others & for years have done the usual lurking in hi-fi shops at all price points listening to all kinds of subs so in other words I know what a sub is supposed to do and sound like. And while not exactly a prolific builder, I have built two sets of speakers and had to research & apply Thiel/Small parameters when doing so.

I think people are judging this sytem strictly by numbers and as I've said several times on this forum, numbers only tell part of the story for any audio system and while it won't knock pictures off the walls, this mutt of a subwoofer can produce much more & much deeper bass in that particular room than the $425 Bostons that it works with. Sorry if that offends anyone but it's true.

FYI: I also am not a fan of "If a piece of gear is older than X years, it cannot possibly sound good". A few months ago a pair of Large Advents, also @30 years old, sold for $450 on eBay. This type of transaction is not uncommon anymore so I am not the only one who thinks this way.

So I have to respectfully disagree - it sounds very close to a "real" subwoofer and I have no other agenda in mind when I say that (and yes, I am very aware of what subwoofer company advertises on this site). I've been able to listen to it for more than a year and am very familiar with its capabilities.

I think part of the problem here is that it is being compared to subs that DO go down to 20Hz and below. Well surprise, not all movies have bass that extends that far or where *all* the movie's effects use only that set of frequencies; and of course 95% of music never extends that far.

This is why A/V sites aren't fun for me anymore - too much of this "its either THAT or THIS" way of thinking, in other words there is basically no in-between, no grey area, no "sounds pretty good".

When I see so many store's audio departments - at every price point - which have been almost completely devoid of customers for the past four years, I personally don't think it is a good idea to advise people there are only two options i.e. complicated/expensive......or nothing at all. IMO it's that kind of yes/no on/off attitude that scares people away from an already-dying hobby, much like the world of modern polarized politics that has caused so many problems lately.

 

[JohnRice]

Lance, you must be dizzy after all that spin. You title the thread "How to make your own subwoofer" and make these outrageous claims about how all you have to do is hook up a random speaker to the subwoofer output and you have a sub that "can produce much more & much deeper bass in that particular room than the $425 Bostons that it works with. Sorry if that offends anyone but it's true." No, it isn't true.

ALL you are gaining is the ability to put the speaker in a better location for bass, and I am not in the least offended, but your info is severely misleading and misguided. I just came in to point that the principle is not rooted in reality. I tried to word it as tactfully as I could, but the hard reality is, any marginal, unpowered sub is likely to produce better results than your homemade "sub".

Now, if you said this was the world's best $5 "sub", I'd have no argument.

 

[troy evans]

I agree with John. It just doesn't seem real, unless you've left something out of your post. For what you seem to be doing all that is really reqiured is to set all your speakers to large. You don't even need the make shift subwoofer. I applaud your efforts, but, I can hardly see them producing true subwoofer capabilities. However, if you are happy then that's all that really matters.