Little 10 watt stereo amp

[Tekko]

So after a bit of a break, im back with a new project, this time a little 10 watt stereo amp using MJE340 and MJE350 as output devices.

Here are a few pics:
http://i.imgur.com/1lPTI.jpg
http://i.imgur.com/w6N9W.jpg

Schematic, its not identical to whats on the board but its pretty close:
http://i.imgur.com/tHp1E.png

And finally, a video:
YouTube - 10 watt complementary amplifier

[Ian Finch]

Hi
I think the MJE340/350 pair are more suited to low current duty. i.e. High voltage and speed but low current. Certainly, not enough current to drive an eight ohm speaker to 10 watts.

For TO126 types, BD139/149 pairs with 1.5 amp max. rating are going to be closer than the MJEs 0.5 amps max. but still not 10 watts.
Then, there are many other less common types that would be far better choices too.

If you don't like multiple devices, which seems inevitable for TO126 size dissipation limits, perhaps some TO220s like TIP31/2 or 41/42 would be suitable.
Doing better still, the MJE15003x series is well worth the extra money.

[lineup]

Besides the weak output transistors you need +/- 14-15V to get 10 Watt into.
With +- 12 Volt you will get 7.5 Watt max. Into 8 Ohm.
Into 4 Ohm you can get 10 Watt

[Tekko]

Yes i know all this, Sheesh! The 10W is a absolute maximum rating. This amp on this wall wort power supply gives around 1 watt per channel.

This thing was a result of boredom and what i happened to have laying around.

It does drive 8 ohm speakers to insane sound levels though without even getting warm.

[Tekko]

After 2 hours of solid hell, this amp dident even get wam, and it was turned up twice as loud as a vacuum cleaner for these 2 hours.

Its still alive.

[gychang]

saw your video, how is the sound compared to let's say t-amp.

[Tekko]

Considering i have a cheap T-amp, i'd say the difference is like night and day. The Lepai LP2020 is a piece of **** in comparison.

Do observe that with MJE340/350 you will only get around 2-3 watts into 4 ohms before the outputs will fail.

However, add some cheap power transitors like BD911/912 and u'll be able to crank up to 50 watts per channel with a decent power supply.

If i want to i can replace the 220mOhm emitter resistors with something like 10 ohms and hook on a bank of power transistors with a nice big fat power supply and have over 500 watts into 4 ohms if i wanned to.

This as just a boredom project put together from parts of a early project which the outputs have long gone on.
¨
Heres an example how to get more power from this circuit:
http://i.imgur.com/IvaXP.png

[T in AZ]

I watched the video and it sounded good to me, nice Amp! Clear and being powered by a wall wart it had base with no distortion that i could hear.