how a solid state amplifier differs from a subwoofer amp

[araven]

Hi all,

I have a number of solid state amps that i have built lately, and i was hoping i could use one in the latest sub i was building. I have just a few questions I was hoping some kind person would help me with.

Firstly, with toroidal PSUs, it's common to utilise a low pass filter to stop the very high frequency distortion that toroidals are notorious at creating, as an amplifier for a subwoofer is obviously only dealing with very low frequencies can this be extended down alot more?

I was also wondering what to do with the zobel filter? Can this be removed?

Lastly, i imagine a very suitable bank of capacitors is needed as most of the sound created requires alot power being low frequency?

Is there anything else i should be aware of using a normal solid state amp in an active subwoofer?

Many thanks,
Andy

[araven]

Sorry, i was also wondering out of curiosity, if one was to make an amplifier specifically for an active subwoofer, is there a particular topology you should use? ie are chipamps, mosfets etc.. better are producing peak amounts of power that low frequencies demand?
I've been told that almost any old amp will do for an active sub because normally distortion only really occurs at higher frequencies, is this right?

cheers,
Andy

[richie00boy]

A few terminology and other things need clearing up

Any amp that uses bipolar transistors or MOSFETs is solid state, sub-woofer or fullrange driving is irrelevant.

Toroidals don't generate high frequency distortion at all, merely any rubbish on the mains can pass more easily through a toroidal than a similar power EI transformer.

The zobel is not a filter. Depending on which zobel you mean (there are about three different zobel implementations on speakers and amps), it's unlikely it can be removed.

It's actually midrange that demands the most peak power. As bass is quite long in duration, relatively speaking it's quite average in nature. But I know what you mean about coping with bass 'stabs'. IMO you still need a good amp for a sub because different amps sound different in the bass. I wouldn't use a chip amp for a sub purely because they are limited in power output, and subs are generally hungry beasts.

My advice to you is pay attention to the grounding scheme and wire routing.

[SamL]

Originally posted by araven


Is there anything else i should be aware of using a normal solid state amp in an active subwoofer?

You need to make sure that your amp is able to drive the sub. Most sub is 4ohm and if you check the impendance chart, they will dip to 3ohm or lower. Not all amp is happy to go that low.

Have fun,
Sam