Cheap DIY Amplifiers

[JonathanAnon]

Re: Cheap DIY Amplifiers

What you mean? The misleading buttons? I was gonna throw it up on youtube, but I didnt want to have to fill out all the forms.

I've just looked at it again, and I think you might be talking about the video quality. That's my fault, I just did a quick vid on my phone.. It's meant to be HQ video on my phone, but it completely loses focus when you bring it in close...

[lti]

Re: Cheap DIY Amplifiers

There are tons of ads and the video takes a really long time to load. The video quality wasn't what I was talking about.

There isn't a need to put on a different website like YouTube unless someone gets malware.

The LM386 isn't a very good chip, but it works okay for headphones and higher impedance speakers (16 ohms or greater).

[JonathanAnon]

Re: Cheap DIY Amplifiers

Okay, I'll load it on youtube in future.

I've tried the 380N 14pin version and it sounds a lot better.

[lti]

Re: Cheap DIY Amplifiers

Like I said in the above post, you don't really need to switch video hosts unless there are more complaints.

[momaka]

Re: Cheap DIY Amplifiers

ive been using a 12v 1.5A power brick, i think its not so much the amp as the speakers, connected it up to a sony 8 ohm cabinet i have around and it sounded a million times better, so i really dont know.

^ THIS.

1W of output power is actually quite enough when played through some proper speakers. If the speakers are ported properly, you can even get quite a bit of bass.

Remember that in order to increase the output sound by 10 dB, the output power needs to be increased by a factor of 10. So let's say you have speakers rated for 80 dB/W (i.e. 80 dB with 1W of power). That means that with 10W, you'll get 90 dB, and 100W will get you 100 dB.

I designed and tested a super-simple Class A amplifier a few months ago, and it was able to drive a pair of 8 Ohm Sony cabinet speakers at a reasonable volume despite only having a maximum output power of about 600 mW.

A switch mode power supply should be avoided because of noise from the high frequency switching.

My dad's Sony TA-F70 amp uses a switching power supply. That thing was obviously designed properly, though, because there is absolutely no noise on the output.

I myself have noticed that not all amps are sensitive to SMPSs. For example, the headphone amplifier I built which uses a Panasonic AN5272, doesn't care at all weather used on batteries or a cheap SMPS brick. It's noisy with both. I also have a pair of speakers that use a KIA6283A amp, and that thing is extremely noisy with SMPSs.

However, the thing to know about most SMPSs is that if there are any "harsh" voltage spikes on the power line from nearby light switches, motors, or relays from appliances around the house, you will likely get a loud and nasty crackle noise on the output as well. Installing proper EMI and RF filtering and increasing the bulk input and output capacitance of the SMPS may help, though.

A switching power supply will introduce some noise compared to a classic big heavy transformer but you probably wouldn't notice the difference with average speakers.

The only problem with using a normal line transformer is that you also need big output capacitors (and those can be expensive). Otherwise, you'll get lots of line hum. I guess a way around that would be to use a linear regulator and waste a few Watts of power at the expense of clean output.