Is it safe to use other adapters with this subwoofer?
May 27, 2013 3:30 PM   Subscribe

I just bought a subwoofer from a thrift shop, but unfortunately the power adapter (13.5 AC in) is missing. My neighbourhood shops seem to be fresh out of adapters with that voltage, so I'm wondering if it would be possible/safe/advisable to use a different adapter? I have several lying around the house with output voltages ranging from 5 to 16V.
posted by The Card Cheat to Technology (15 answers total)
the lower the voltage, the more amperage it's going to draw. And there's other problems it might cause from the power "sagging".

Generally, an unloaded not-switching power supply like the ones used in those little bricks actually has a much higher voltage than 13.5, like maybe 17 even. What i'm saying is that the voltage the sub is getting when it's not playing anything is probably a lot higher than 13.5, that's more of just a nominal thing. I've seen 12v bricks read like 14-15v on a multimeter.

If it's a crappy power brick it might even drop below 13.5 when you have the sub absolutely cranked, also.

I'd use the closest to the rated voltage one i have that's above 13.5, and look closely at what the rated amperage is. If you have a 12v one laying around that's rated a bit higher than the original(say, the original was 2 amps and the 12v one is 2500mah or something) then i'd try that too.

You're almost definitely not going to blow the thing up though, especially if it's just accepting AC current as input. That kind of stuff seems to be a lot less finnicky about what it'll handle.

Possible? Definitely. Safe? i don't really see why not? Advisable? I would say so, but then again i'm slightly crazy and do stuff like this almost every day. I've soldered new tips on to different power bricks to use with stuff worth >$150 just because i wasn't about to order the official/an identically specced brick on ebay and wait a week to be able to use the thing.

I've never, ever wrecked something this way. And an engineer-type friend who works on industrial robots and all kinds of other fancy stuff stated pretty plainly that almost all consumer electronics stuff is designed with a whole bunch of play in what input voltage it'll accept, especially if it's of any quality at all.

If you want to be super careful, don't crank the thing up super loud until you've let it play at a moderate volume for a half hour or something and seen how hot it's getting, if there's any weird smells from the amp getting too hot, etc.(and bear in mind some sub amps just run REALLY hot, my old klipsch promedia was like a nuclear reactor). Just feel it out and don't go whole hog at first.
posted by emptythought at 3:54 PM on May 27, 2013

Response by poster: The closest adapter I have that is above 13.5 is says OUTPUT: 16VDC 900mA. I have no idea what it was originally supposed to power, as I fished it out of a box in my basement.

I know I could order one online, but I'm a bit impatient and grumpy because I walked to The Source, Canadian Tire, Staples, Wal-Mart, an indie hardware store and a dollar store and none of them had an adapter in 13.5, or even a universal adapter with that setting.
posted by The Card Cheat at 4:05 PM on May 27, 2013

A clarification question - does the subwoofer specify 13.5v AC or DC input? Your original post says AC but your latest comment refers to an adapter with DC output. Using a different voltage might be OK, but you need to feed it the right kind of current.
posted by under_petticoat_rule at 4:24 PM on May 27, 2013

Emptythought is right in that most products are designed to be conservative and safe in their power regulation. You NEED to use the right electricity type (DC vs AC) and polarity if it is DC (center negative or center positive). Other than that, you can try different voltages and amp ratings as long as they are in the right ballpark - it is really unlikely you will hurt it by giving it 16v or 12v for example, as any sensitive bits will have power regulation before them. And the more amps a power supply can put out the better - but you will most likely not damage anything by not giving it enough amps.
posted by ianhattwick at 4:31 PM on May 27, 2013

Response by poster: Subwoofer says 13.5v AC in, every adapter I have lying around seems to output in I guess I'm out of luck until I order something.
posted by The Card Cheat at 4:34 PM on May 27, 2013

Well, if you are the type who doesn't mind experimenting and occasionally blowing things up, you could try plugging in the 16 VDC adapter and just seeing what happens. (I'm guessing you didn't pay much for the speaker.)

13.5 VAC has a peak voltage of 19V so you wouldn't be exceeding the peak. The AC power for the speaker goes into a DC rectifier which is then filtered and regulated. If the half bridge of the rectifier can handle the full load current, then it might work. Polarity of the adapter shouldn't matter for a AC input.

Your 900 mA adapter at 16V is only capable of 14.4 watts, so what is the power rating of the speaker in watts?
posted by JackFlash at 5:13 PM on May 27, 2013

Response by poster: Here's a page with the specs for the subwoofer...looks like 90 watts.
posted by The Card Cheat at 5:18 PM on May 27, 2013

Only 24 watts for for the subwoofer alone. That would be at maximum volume.
posted by JackFlash at 5:38 PM on May 27, 2013

Response by poster: I'm getting a bit confused...when I google "13.5V AC adapter" I get stuff like this, but its output is listed as DC. Could someone point me to the sort of device I should be buying?
posted by The Card Cheat at 5:46 PM on May 27, 2013

I think they mean an AC-adapter that outputs 13V DC from a 110V AC input.

A component that converts 110VAC to 13VAC is normally called a transformer, and it would be utter madness to supply that as an external adapter with a speaker.
posted by monotreme at 6:28 PM on May 27, 2013

After some googling, the power adaptor needed is six amps(check out this) and it is indeed an AC input, not DC.

So yea, you don't need a AC to DC power brick like... 99% of things use, you need an AC-AC brick in the 12-16v range, probably that puts out around 4-5 amps. Look at the brick in that PDF, it's serious and covered in heatsink fins.

It's worth noting that in these systems the amps for all the satellite speakers, even if they aren't connected are in the sub. There's no way to just run the sub amp, although it should draw a bit less power without the satellites connected it's still going to draw a good amount.

I'm also supicious, that since this is one of the systems that had a little volume+power button unit that sat on your desk to control the whole system... that it might not even turn on without that. I've played around with PC speaker systems like this before that worked that way.

As in, if you just have the sub and not the little control box pictured in that PDF, it might not work at all.
posted by emptythought at 6:34 PM on May 27, 2013

The original Creative power supply is an oddball custom job rated 13.5 VAC 6 amps. Yes, the output is AC, not DC. You aren't going to find the equivalent on the market but there are some out there used. For example here for $66.95. I'm guessing that's a lot more than you paid for the speaker.

So another alternative is here with picture here. You would have to put the wire and adapter plug on yourself. You only need 24 watts if you are using just the woofer amplifier so 2 amps should be sufficient.

Like I said before, if you just want to find out if the thing works and aren't worried about possible damage, just plug in the 16 VDC adapter and see what happens. Don't turn the volume up too high. The DC input to the speaker's rectifier should be just fine because 13.5 VAC has a peak voltage of 19V.
posted by JackFlash at 6:35 PM on May 27, 2013

Response by poster: Hmm. Thanks for the advice, everyone, but it looks like I might be better off just returning the thing.
posted by The Card Cheat at 6:43 PM on May 27, 2013

You might almost be able to find a doorbell transformer that would do the job, which might be cheaper and easier than ordering something from digikey. They're usually a bit undersized for this job but maybe a largish one would be able to supply 24W…? Anyway, I think you're probably right that getting this to work is not worth the trouble, unless there's something you particularly like about this wubwoofer.
posted by hattifattener at 9:28 PM on May 27, 2013

Given the price of new speaker systems, I'm constantly telling people not to mess with trying to get a broken / half working speaker they found on the street to work. Unless you really want to learn or experiment.

I would assume that a DC supply just wouldn't work with an AC amplifier - but I haven't worked with AC circuits much so don't know how true that is.
posted by ianhattwick at 12:52 AM on May 28, 2013

« Older Well, this still sucks   |   Is it worth it to open a high yield savings... Newer »
This thread is closed to new comments.