Extremely cheap headphones amplifier

[Rullknufs]

Hi!

First of all i'd like to say i'm not sure if this is the right place to post this thread. If it's wrong feel free to move it right


Well, the thing is i use my headphones quite much, especially on the evenings. Much because my parents don't want me popping Meshuggah at full volume (sort of).
Right now i power the with *badam-tisch!* built-in soundcard of Asus P6T Deluxe V2. Quite shitty. And the headphones are a pair of SteelSeries Siberia V1. Not the best but i can't afford any better atm and they've been whole for almost two years.

So i thought of building an extremely cheap headphones amp that are better than the built-in soundcard. I want to get it as cheap as possible (how cheap is it possible to go?) and the size to be quite small. It will be on my desktop but i still want it to be portable. I will connect it to my computer and probably my phone (when in the car).

Is it possible to get one for around 20-30$? I can order from Elfa, i think they're located here in sweden.

//Niklas

[jaycee]

Depending on the headphones, an NE5532 opamp alone might drive them OK. For a little extra current you could use an arrangement similar to this:



Rail voltages of 15V are shown but it would also work with 2x9V PP3 batteries. In this case you could probably use some smaller transistors, such as MPSA06/56.

[Rullknufs]

Oh, i forgot to mention that my knowledge about this is 0. I haven't done anything at all with amplifiers. The closest i've been is assembling some computers and soldering some speaker cables

Edit: If we find something interesting it would be nice with a list of what is needed

Edit 2: Would be nice if it's easy to build. I could possibly get somebody who can do it for me but i'd prefer doing it on my own
And i don't understand how that thing smaller than 1x1cm should be able to power my headphones only. How do i connect it?

[john blackburn]

Hi Rullknufs.

If it is a first amp build why not try a cmoy? How to Build the CMoy Pocket Amplifier

No mains wiring, good tutorials and a well tried and tested design so debugging is easier.

John

[Rullknufs]

Thanks a lot John Blackburn. Hopefully i will have internet (mobile interner though :S) so i can read that while traveling south

[sakis]

ok ... lets take one step at a time .... your pc has some type of cpu that includes a dac inside or your sound card has a dac ...that takes digital signals and convert them to audio ...then your sound card has some IC probably smd 4560-4580 or 5532 that is configured as amplifier ...and then you like to use another amplifier like the one shown above that is actually the exact same thing = a 5532 as a voltage stage and external tranistors as a current stage ...

as i see it its way too many things in the signal path .... especially what causes the real trouble is the ic that is installed as an audio amplifier in your sound card ...reason = is that any op amp that is used as a headphone amplifier aims to power and stabilty and not quality

solution :
facing the exact same problem i canibalized my sound card to remove the headphone stage ( 5532) and used actually the output from the dac for a line out ...a real line out ... gain is kinda low but that is not importand since al modern mixers have gain controls or the amplifier shown by jaycee has enough gain to drive anything ...

you will be amazed by the results ...chanel seperation and stereo image is amazing and frequency responce is by far better than used to be before ..

regards sakis

[jaycee]

Good advice Sakis, but with his level of skills this is not really possible for him.

If it's onboard sound, then the amp is usually poor as it is driven from 5v (really!) and capacitively coupled. Yech.

A good start would be to use an NE5532 opamp as a buffer. Even powered from 2x9V batteries, this should improve things a lot. It's also a good safe starter project you can make on stripboard.

[Rullknufs]

I have been thinking a little. What if i make it non-portable? Would that be better? If i power it via 12v or something? Or the usual 230v or whatever it is?

[zebra100]

A Szekeres class A single MOSFET (IRF513) follower might be right up your street. I've just finished modifying mine (to enable it to be fitted into the passive attenuator that I use for my gainclone) which I've been using for over a year. It is truly a wonderful design, and very easy to put together on stripboard. It does need a regulated power supply though, and I use a 13.8v/20W supply. I used a LM317 voltage regulator as a constant current source, which is in the data for the project (HeadWize - Project: A Class A MOSFET Headphone Driver by Greg J. Szekeres).

It sounds very clean, with bags of detail. A very neutral sounding amp. It doesn't cost too much for all the bits, but to buy this kind of sound quality, you would have to spend an awful lot of money.

Regards,

Chris.

[godfrey]

Originally Posted by Rullknufs

... If i power it via 12v or something? ...

I like the 12V idea. At home you can power it from the computer's 12V supply and in the car you can power it with 12V from the cigarette lighter.

It saves the hassle and expense of building a power supply - you'll just need a couple of adapters/connectors and a filter in the amp to get rid of noise on the +12V line.

Rechargeable batteries are good too - probably the best option for sound quality. The only downside is the cost of the batteries and charger.

Cheers - Godfrey