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September 25, 2013

Subwoofer Amplifiers: Sourcing and Building a Robust Amp

Subwoofer amplifiers vary in weight, size, and length of warranty. What should you look for in a subwoofer amp? In this video, we tell you how we source our amp parts, according to what pieces make a difference.

Andrew Welker: Previously we’ve done a video showing you different adjustments and connections that are available on our subwoofer amplifiers. We decided today to shoot a video in the Axiom Electronic Prototyping Lab (you can see all the components behind us in the small containers).

We wanted to talk about the part of the subwoofer amplifier that you don’t see, because from the outside, most amplifiers look pretty similar between different companies. It’s a flat piece of metal. Sometimes there will be a heat sink, sometimes there won’t be, but basically they’re all rectangular or square plates on the back of the subwoofer.

That’s important because it’s the interface that you, the customer, has for making connections and adjustments to your subwoofer. But the real ‘meat’ of the amplifier is going on in the inside, and it’s on the inside – unfortunately the part you can’t see – that tells us a lot about the quality of the amplifier and where your money is going.

All Axiom amplifiers, whether they be subwoofer amplifiers or stand-alone amplifiers, use something called a linear power supply. All that means is that it is a fairly old-school large toroidal power transformer and large filter capacitors.

If you look at many amplifiers for subwoofers that are on the market now, they use something called a switching power supply. They’re much less bulky and and much lighter, and in many ways they’re more efficient (at least in standby), but one of the reasons we use a linear power supply instead is because frankly, it sounds a lot better! You have better dynamic capability, better headroom, and a linear power supply can respond to current demands much more quickly than a switching power supply.

One of the other things that many people don’t realize is that switching power supplies don’t have a very long life in general. If anything goes wrong with most subwoofer amplifiers, it’s usually the switching power supply. One of the things that tells the tale to the consumer is to look at any sub you’re looking at buying, and checking out the warranty. The warranty for the amplifier should be the same lenght of time as the warranty for the whole subwoofer. In the case of Axiom’s subwoofers, that’s 5 years on everything. Many manufactures will only warranty the amplifier – the electronics portion – for only 1 year. You should wonder why the manufacturer doesn’t have enough confidence to warranty the electronics for the same length of time as the loudspeaker, because frankly the amplifier should last as long as the rest of the subwoofer.

This is the reason we use a conventional linear power supply.
A) because it sounds better and
B) because it lasts longer.

Now, also at the heart of the amplifier is the amplifier board itself. All of the amplifiers in Axiom subwoofers are Class D or switching amplifiers. This is a class of amplifier that is very efficient. They run extremely cool, which is also important for longevity. Ours are completely designed and manufactured in-house.

One of the reasons that’s important is many manufacturers are buying so-called plate amplifiers for their subwoofers off the shelf from some company that has designed the entire amplifier. One of the issues with this is you can never really guarantee every component that goes into the amplifier. This has some impact on longevity as well.

Every single component on our amplifier boards and DSP boards are sourced and supplied by us, and in terms of critical components they’re actually sourced here in North America and then they are sent to our vendor for populating in Asia. Why is that important? It’s another area where you want to have very tight control over the manufacturing of your product, because there are a lot of counterfeit parts out there and those can have a huge impact not only on the sound quality of your amplifier but also on how long it last.

Hopefully that gave you a little bit of background as to why our subwoofer amplifiers are more traditional in that they use one of these large transformers, and they’re fairly heavy: it’s all for quality and for making the subwoofer amplifier last.

President’s wife 🙂 Defacto, that makes her an audio guinea pig, whose only request to the lab is to always run sample products in colors that blend in with the rest of her home!

She considers herself the Audiobyte’s Number 1 fan.

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1 Comment »

  • March 16, 2014 at 5:57 am

    very good information about sub-woofer thank you,

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