How much does the quality of a sub amp matter?

[Javaman]

Is it true that to the human ear sonic quality matters less and less as the frequency goes down? And if so shouldn't I just buy the cheapest plate amp with sufficient power and the features I need or... are there other factors involved that would justify
spending more

I was also wondering what the pros and cons of using an amp with a built in X dB boost. Dickason uses the full 6dB in his little sealed Parts Express kit - this seems too easy, what's the catch?

Any feedback highly appreciated.
thanks
<peter>

 

[subwo1]

I have not heard much on the subject except a similar general concept. I have actully read that most woofers produce much more distortion than the amplifier. However, the sub I am working is cleaner than most. So, for my project I have decided on the arbitrary figure of 2% depending on the type of distortion, but I am considering that up to 10% may not really matter. Right now I have not come up with an amp design I like to power the sub, so I am not sure what figure I will actually end up with.

 

[The Paulinator]

I dpersonally don't beleive that they do. I have run a few tests and I beleive that the sub woofer is probably the speaker that you need to worry about the least as far as quality of amplification.... of course, that doesn't meen to disregard quality altogether. If the amp is true to it's published specs and has sufficient power, I think you would be fine with almost anything.

 

[AudioFreak]

so long as the amp is tight and sharp in the bass it probably wont matter if the amp alone has 5% distortion as humans are flat out hearing in the lowest octaves.

 

[The Paulinator]

I thiink pretty much any amp will be "tight and sharp" in the bass, as long as you don't ask it to overstep it's boundaries. I once had a Sentrek 30x2 car amp bridged running a pair of 10" subs, and to this day I cannot remember ever hearing cleaner bass (except maybe with my 90x2 Sentrek that is running my older Oz audio 12" in my car).

 

[kelticwizard]

Add me to the list of people saying that you hear less distinctly as the frequency goes down. Articles published in the Journal of the Audio Engineering Society confirm this. So yes, I would be inclined to say that the biggest concern with sub amps are power and reliability.

Besides, I think most of them are made at one of two factories in China anyway. They put different brand names on for their OEM customers.

 

[Sch3mat1c]

Remember...those higher harmonics *are* still audible...so a filter (crossover) at the speaker will clean things up a lot. Would seem to me that you could also allow a *lot* of distortion at the upper limit of the setup, as long as the xover has good rolloff before the next octave or two (2nd or 3rd harmonic).

Tim

 

[roddyama]

Although it is probably true that the distortion created by most conventional amps will not be an issue when powering a subwoofer, however the amps power supply will be an issue. Woofers are highly reactive when operating in the region of their fs and will display relatively high impedances. This requires all the voltage you can muster to drive the current through the voice coil of the woofer in this region. If the amps power supply is too wimpy, as the current demand goes up the amps voltage rails will start to sag. The result is a sub that just doesn’t have the punch or tightness you’d expect.

Conventional amp power supplies require a lot of storage (supply capacitors) to keep the current flowing without sucking the voltage down when driving a woofer. Storage is expensive. So for a conventional amp, I’d say it shouldn’t be just any cheap amp.

Now when you start to talk about Class D amps or Inductor based power supplies, that a different argument. Distortions levels may come into question again, and you'll have address Tim's issue how it sounds in the woofers stop-band region.

Rodd Yamashita