Amplifier with 2N3055

Tekko · 4th December 2010, 02:00 PM

I was a bit bored and looked over at a disassambled regulated psu that has two 2N3055's in it and thought "i wanna build an amp with that!"

Heres the result after a few hours in simulation:
schematic with sim

mnemneth · 4th December 2010, 02:36 PM

First thing I noted is with your diff amp degeneration resistors R9, R16.

You have them shorted out, as your distortion text also indicates.

Sandy

Tekko · 4th December 2010, 04:49 PM

And now its playing:

http://i.imgur.com/LZPi0.jpg
http://i.imgur.com/SwGJg.jpg

This s the schematic on the board:
http://i.imgur.com/WAVUF.jpg

As im posting this, the amp is blasting music at pretty high volume.

godfrey · 4th December 2010, 05:29 PM

Quote:

Originally Posted by Tekko

... two 2N3055's ...

So if you want stereo, it'll have to be single-ended class A.
Hehe - look Ma, only 30W dissipation for 2.5 watts output.

Tekko · 4th December 2010, 05:36 PM

If i want to make a stereo version of this, i'll just get more 2N3055's, their dirt cheap.

This heatsink is way undersized anyways, its already HOT!! And this amp runs only 100mA bias.

I have in a box at my old adress a large heatsink with 8 TO3 devices on them, actually 2 but the other one is clean.

Tekko · 5th December 2010, 11:02 PM

Update:

The two 2N3055's have been replaced with four 2N3716 on a much bigger heatsink.

However making that work was a chore, it took me half a day and loosing a transformer to find out that one of the 2N3716's had a short from c to b.

However once that transistor was disconnected and replaced, the amp sprung to life.

nigelwright7557 · 5th December 2010, 11:36 PM

Quote:

Originally Posted by Tekko

Update:

However making that work was a chore, it took me half a day and loosing a transformer to find out that one of the 2N3716's had a short from c to b.

Its worth fusing the secondaries to save the transformer if a short occurrs.

I have missed out the fuses myself before on a test rig,
Next thing I knew the transformer was bubbling due to a short !
Luckily i caught it just in time before the windings all melted together.

Tekko · 5th December 2010, 11:59 PM

In my case i dident notice it since the transformer was inside a plastic box down on the floor, when i heard the plastic bobbin bubbling and saw the smoke, it was already too late

Secondary had already developed interturn shorts.

Tekko · 6th December 2010, 12:38 AM

Pics of prototype:

http://i.imgur.com/gDaaR.jpg
http://i.imgur.com/t8agH.jpg
http://i.imgur.com/aaC9X.jpg

Antithump delay:
http://i.imgur.com/gjs06.jpg

Tekko · 8th December 2010, 09:17 AM

Cleaned it up alittle:

http://i.imgur.com/3FFB1.jpg
http://i.imgur.com/rPFhY.jpg
http://i.imgur.com/XV264.jpg
http://i.imgur.com/yyEeC.jpg

Schematic:
http://i.imgur.com/UlYNn.jpg

It works and sounds really good.

4th December 2010, 02:00 PM	#1
Tekko diyAudio Member Join Date: Jan 2005	Amplifier with 2N3055 I was a bit bored and looked over at a disassambled regulated psu that has two 2N3055's in it and thought "i wanna build an amp with that!" Heres the result after a few hours in simulation: schematic with sim

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4th December 2010, 02:36 PM	#2
mnemneth diyAudio Member Join Date: Feb 2006 Location: Dundee	First thing I noted is with your diff amp degeneration resistors R9, R16. You have them shorted out, as your distortion text also indicates. Sandy

4th December 2010, 04:49 PM	#3
Tekko diyAudio Member Join Date: Jan 2005	And now its playing: http://i.imgur.com/LZPi0.jpg http://i.imgur.com/SwGJg.jpg This s the schematic on the board: http://i.imgur.com/WAVUF.jpg As im posting this, the amp is blasting music at pretty high volume.

4th December 2010, 05:36 PM	#5
Tekko diyAudio Member Join Date: Jan 2005	If i want to make a stereo version of this, i'll just get more 2N3055's, their dirt cheap. This heatsink is way undersized anyways, its already HOT!! And this amp runs only 100mA bias. I have in a box at my old adress a large heatsink with 8 TO3 devices on them, actually 2 but the other one is clean.

5th December 2010, 11:02 PM	#6
Tekko diyAudio Member Join Date: Jan 2005	Update: The two 2N3055's have been replaced with four 2N3716 on a much bigger heatsink. However making that work was a chore, it took me half a day and loosing a transformer to find out that one of the 2N3716's had a short from c to b. However once that transistor was disconnected and replaced, the amp sprung to life.

5th December 2010, 11:59 PM	#8
Tekko diyAudio Member Join Date: Jan 2005	In my case i dident notice it since the transformer was inside a plastic box down on the floor, when i heard the plastic bobbin bubbling and saw the smoke, it was already too late Secondary had already developed interturn shorts.

6th December 2010, 12:38 AM	#9
Tekko diyAudio Member Join Date: Jan 2005	Pics of prototype: http://i.imgur.com/gDaaR.jpg http://i.imgur.com/t8agH.jpg http://i.imgur.com/aaC9X.jpg Antithump delay: http://i.imgur.com/gjs06.jpg

8th December 2010, 09:17 AM	#10
Tekko diyAudio Member Join Date: Jan 2005	Cleaned it up alittle: http://i.imgur.com/3FFB1.jpg http://i.imgur.com/rPFhY.jpg http://i.imgur.com/XV264.jpg http://i.imgur.com/yyEeC.jpg Schematic: http://i.imgur.com/UlYNn.jpg It works and sounds really good.