Subwoofer AMP

[fschris]

I am a total noob but I am looking for some help. I am interested in building a DIY home theater sub woofer amplifier. After reading on Parts express and poking around other forums I was wondering if I could build my own Subwoofer AMP. I have some electronics knowledge and I could certainly put a kit together soldering and such. However design and sourcing capacitors, transformers etc would be a bit over whelming. Can anyone suggest a kit I could put together ... or should I just stick to the retail route. I am interested in doing something myself if it not incredible time consuming.

My goals would be :

1) a better than an off the shelf 300-500w amp (is it me or do the plate amplifiers built cheaply ?)
2) a bit cheaper since I am D-I-Y
3) Help me understand the basics of amp building.
4) not electrocuting myself building this.

My Sub design goals would be to reach 20Hz with authority. I have a small home so it does not to be SUPER loud.

[Tekko]

See apexaudio quasi amp for beginners.

[CBS240]

Consider the criteria for a sub-amp. Subwoofers can have very low impeadance at a significant phase. But they are only suitable for a very small frequency band at the low end so this simplifies the circuit significantly. A mirror loaded input diff and a CCS loaded single end VAS should suffice. There are also Op-amp solutions. You will want to overbuild the output stage and drivers as well the power supply. Extra resevoir caps to handle the low frequency energy. 500Wrms @ 4R is about 63Vp and would require many output devices. It does not sound like you really need 500W though.

When you decide on a specific power level goal then you can design the output stage. IMO, I would not use a CFP output stage but rather a follower to drive a sub.

[madtecchy]

Hi
What sub will you be using ????
Regards mad mark

[AndrewT]

Hi,
do you want/need a sub?
You have specified 20Hz to 100Hz. This is bass.
Sub is designed for significant output below 20Hz, eg. sound effects.

A TH can be designed that can use upto 100W for deep and strong bass from 25Hz to 80Hz.

If you select a driver/s that can give you 110dB @ 25Hz that is a lot for a small room.
120dB @ 25Hz is an all together different target, but achievable. You are into big driver Sd.
110dB to 120dB @ 20Hz is another step change up in Sd requirement.

Determine the overall goal first, then see what fits your room and your budget.
Amplifier design and build is near last on the list.

[fschris]

Okay thanks everyone. I will think about this for a bit and do some more reading.