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Inexpensive Subwoofer amplifier for DIY project.

FrantzM

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Hi

I already have a pair of cheap subwoofers. They work but I need more. I had my eyes on the HSU VTF-2 MK5. By the time it would come to my door it would cost me about $1350.oo, double the US price. Supply -chain problems are real people.
So why not build one? My woodwork skills are nil I am thinking that a Sonotube subwoofer could be a solution, since those concrete forms are plenty-available where I live. I would like to keep the total cost of the project under $500.oo
I need an inexpensive amplifier for the subwoofer.
My requirements:
  1. Class D or anything extremely efficient in term of power usage.
  2. Cheap, very, inexpensive.
  3. at least 300 watts at 8 Ohms and capable of driving down to 2 Ohms.
  4. >=75 dB SINAD
  5. Must be able to go down to 10 Hz within its passband. Don't care about drop in power above 500 Hz. Don't mind about rising noise, THD or IMD above 500 Hz too.
  6. Small and self-contained. I would like to avoid outboard Power supplies.
  7. It can be butt-naked but a decent case would be nice.
  8. DSP not necessary, but nice if it has it.
  9. Did I mention, inexpensive?
  10. around $200, shipped to the US?

The impetus is that with the current shipping prices and (high ) local custom fee, a subwoofer of the size of the HSU will cost me twice its USA price or perhaps more. The Sonotube with a good driver should achieve similar , if not better results and cost much less.
 
OP
F

FrantzM

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need one channel. 300 watts, stable to 2 ohms For subwoofing duties.
 

DVDdoug

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You can probably find a Plate Amplifier. But 2-Ohms might be a problem and they are made to mount in a flat surface. 10Hz might also be a problem.
 

mdsimon2

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Got it. Kind of tough because at that power level in to 8 ohm you are likely looking at a bridged stereo amplifier which will have difficulty driving down to 2 ohm. Sabaj A8 based on the ICEpower 125ASX2 module is close, 250 W in to 8 ohm, definitely stable to 4 ohm bridged but not sure about 2 ohm, ~90 dB 5 W in to 4 ohm SINAD and about 0.5 dB down at 10 Hz. However at $260 it is a bit over your price range.

What sub are you driving? Do you really need to go down to 2 ohm?

Michael
 

alex-z

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Your power requirements don't match the budget.

A Crown XLS1002 will do what you want, but is $375.

Dayton SPA300-D is $150, but only does 300 watts into 4 Ohms instead of 8, and probably isn't 2 Ohm stable.

Yung SD500 should have enough power, but is $250, and still unlikely to handle 2 Ohm load.
 

DVDdoug

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My woodwork skills are nil I am thinking that a Sonotube subwoofer could be a solution, since those concrete forms are plenty-available where I live.
The shape of the cabinet isn't critical. It's the volume, and port dimensions if you choose to go with a ported design. (And of course the woofer is important.) WinISD is a free application that can help you optimize cabinet design, given the Theile/Small parameters for the driver.
 

mcdn

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Why are you specifiying power into 2 ohms but only a single channel? Most subwoofer drivers are either 4 or 8 ohms, or dual-coil at 2 ohms per coil.

The way to do this is to select the driver and box you want and any frequency compensation (e.g. Linkwitz Transform) you will apply. This will allow you to calculate the power requirement (e.g. a sealed enclosure with large LF boost needs a lot more power than a vented one for the same loudness at 10Hz).

https://speakerboxlite.com is a great place to play with the basic driver choices and enclosure parameters.

You probably don't need more than 200W into 8 or 4 ohms, so something like this would work well: https://www.aliexpress.com/item/330...46.16!!!!!@2100bb5116531026565527228e5eb2!!sh
 

Chrispy

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I'd still build 2, that's where some economy comes in as well, particularly using a decent 2ch pro amp. Might need to start with one....and instead of the Crown XLS1002 I'd look at least at the 1502 or above....
 

Chrise36

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The Behringer KM750 should do the job.The NX 1000D is even better.
 
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voodooless

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I’ve seen some amps on AliExpress and Alibaba that might fit the asked specs. In fact I’m looking for something similar, though I have a strong favor for DSP enabled amps). Sadly, no way of knowing what the quality is of those things…
 

kiwifi

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bigjacko

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Are you able to diy the amp section too? Don't know if that route can get you cheaper, but at least you can get amp modules that meet your power spec. You can even throw in 3e audio dsp if you want.
 

voodooless

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I’m eyeballing this thing:


Looks like it uses an adau1452 and some 100 SINAD Cirrus codecs. So should be better than the usual adau1701 or equivalent.

The board can actually do 4 channel audio, so one could do all the X-overging for a sub-sat system on that thing.

Not sure about the software capabilities though. It doesn’t seem to support FIR, although the chip is capable of 24k taps.

Also, at almost 300 euros it’s quite close to the Hypex FA251. Less power, but at least you know what you’ll get.
 

Poultrygeist

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A single Yung 300 watt plate amp drives both.


P5080061.jpeg
 
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