Cheap 100 to 150 Watt Amp

keep off

this amplifier doesnt work ...there is been a lot of noise about it many also including me tryied to modifiy this but it doesnt work

john fisher is avery nice guy also a friend but after all this time he has to remove this post about this cheap 150w amplifier since it doesnt really work ...its extremelly unstable

Sorry Sakis, but I disagree. This amplifier does work, but you wont get 100 watts out of it with those output transistors. I've had it working but only up to about 60 watts. I didn't get any oscillation and built it on veroboard as well as a PCB.

Tony

i recon ....

that you should read my posts about amplifier use or abuse .....

then on the other hand if you sup this with 30+30 vdc drive gendle loads and generally be nice to the amp ...yes this will work .... but with voltage more than 34+34 things getting critical ....also not relly omportand what kind of out you are running cause my version had MJ 11015-16 from on semi but still as rail voltage increase together instability distortion and ocilation increase .....

also there is a very big issue about tip 147 or bdv 66 -67 that can be used ...its not that they have to be matched but actually paired meaning that eventhough say that they are complementary if come from diferent factory may be P or N might have diferent charcteristics between driver and out transistor

any way i wouldnt go for an amp like that

ALL THESE

have more or less the same problems ....they have to be the same make the same small numbers ...from the same mama.....

but still this is not going to make a stable amp whats your rail voltage ????

look at mine ...so nice work but prooved to be not stable ( but i also used quiet high rail voltage.....)

That amp is a disaster waiting to happen, its been discussed here before.

The good news is after it blows up in your face, you still have the most expensive parts to re-cycle for a real amplifier (power supply , chassis, and heatsink).

Buy a pair of Pass A40 boards for $6 each from AudioXpress.com and build a class AB version of it.

I've used that board (with suitable transistors) at up to 600W/4R on ±95V.

Hello

Here's a thread where they talk about that amp and give some modification do do.

http://www.diyaudio.com/forums/showthread.php?threadid=100618

Gaetan

No self respecting audiophile would build this piece of crap.

Hey burnedfingers its not supposed to be an audiophile amp its a guitar amp so the more distortion the better
Tony

Your asking the thing to pass music....not act like a ticking time bomb.

Buy a pair of Pass A40 boards for $6 each from AudioXpress.com and build a class AB version of it.

Click to expand...

Buy the Pass boards.

done ....

the same mistakes .....many times i thing

your pcb is very nice ....art work i dsay all of it theoreticlly looks perfect

so please let us now about your rail voltage

and final results

Hi to all

perhaps...

- The BDW83/84 are darlington and Vbe = 0.6x2 each bjt
I have not verified but for a bias of Ic = 10mA
it can try a series of 3 diode 1N4007 and a resistor
from 0.2 to 2 Ohms. (adjust this for appropriate Ic current)
- For better thermal stability increase Re 0.33 with 0.47 or mount
the diodes on BDW heatsink
- increase bootstrap capacitor to 47uF
- decoupling supply for differential amplifier
(split the 22K resistor in 20K + 2K and insert a cap)
- add a rc snubber on output if necessary

bye

my point ....

exactly add a litle here and some there and you will end up with a real amlifier

but lets see our eastern friend come up with very nice pcb perfect layout ....lets wait to here some results also

chears ....sakis

Hello

Here's a simple 100 watt amp that you can build;

http://www.elecfree.com/circuit/pow...r-amp-otl-100w-by-transistor-2n3055-with-pcb/

The link are named 3055 , but it is using MJ15003 and MJ15004 output transistors.

I never try it, so I don't know how good it would sound.

Gaetan

WELL.....

any news from our friend with the simple amplifier???

stil waiting

for any results .....

i like very simpelcircuits my shelf a lot ....so may be i constructed with mistakes .....

may be our friend did better ....lets hear it

Personally, if you want a cheap, reliable 100W amplifier, I would go with sixtek's design shown on this thread:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=100907

You can build that with quite a few different types of transistor, and even leave out T10/T14 and associated parts if you want to cheapen it a bit more - but really, you don't get cheaper than that without it being seriously unreliable.

Cheap and easy ... think not. Besides this thread, there are 2 more about this circuit. I red them very carefully, and this one too, but didnt find an answer for my problem. Here they are :
http://www.diyaudio.com/forums/showthread.php?s=&threadid=15415
http://www.diyaudio.com/forums/showthread.php?threadid=100618

I wanted to make this amplifier for a subwoofer, that I made, but I keep getting +21V "offset" at the output with grounded input. I used this schematic to make my PCB.
http://www.diyaudio.com/forums/attachment.php?s=&postid=179316&stamp=1053546062
Everything on the PCB is correct, and the parts are good. I only changed R7 to 1k to reduce the gain, and increased the bootstrap cap to 47uF. Why do I keep getting the TIP142 half-opened...and there is half of the positive supply at the output. I am powering with +/-42V.

How can I fix this ? Someone said, that he built this amplifier by this schematic and it worked good...well it's not !

p.s. I tried to increase R5 to 3.3k, and reduced R6 to 18k, and the offcet is about 200mv or so, but when I power it up with grounded input and 8ohm speaker connected it makes some rumbling sounds that don't sound good...and i'm afraid to connect a signal source. (my PC)