Budget amp work-over :)

Tenson · 7th July 2011, 09:51 PM

I picked up this amp for my girlfriend for a total of £14.

Now I know it is not perfect but I'm really impressed for the money, even when it was £60 new.

Pictures on my forum here - AudioSmile Forum - View Single Post - Recommend me a girlfriend system

So what do you guys think? Is it worth changing anything? I think I should up the smoothing caps from the 2x 2,200uF per rail but I'll have to see what fits.

I'm uncertain how good the NE4558 op-amps are. I'm not someone who changes stuff because it isn't 'audiophile' so does anyone have distortion measurements for these? How is IMD? Worth changing for the lovely NE5532?

Please post your comments on my forum if you like.

Tekko · 7th July 2011, 09:55 PM

Low budget indeed, the VBE multipliers dont even have thermal contact with the heatsink!!!

That amp is guranteed to go into thermal runaway!

Tenson · 7th July 2011, 10:02 PM

Thanks, I didn't notice that! I'll stick them on.

jaycee · 7th July 2011, 11:15 PM

There is probably no point swapping the opamps as all the audio seems to go through these PT2314 Audio Processors

That is a nice case though. You could probably build something better inside it in future

Tenson · 7th July 2011, 11:22 PM

I'm not sure they are actually installed on the PCB. Obviously not on the top layer, I didn't look underneath but it doesn't look like 2-layer to me. Perhaps a precaution for the future?

Does that look like leaking smoothing capacitors to you, on the main board? Or is it just a bit of glue?

jaycee · 7th July 2011, 11:29 PM

They will be underneath, probably the SOIC versions of the chips. This can still be done on a 1-sided board.

The black stuff is just glue. I'd say it's probably worth pulling those and fitting some good quality 4700uF capacitors.

For £14 absolute bargain. Even for £60 it's good for the price of the case, heatsink, transformer and output transistors (assuming they are 2SB817/2SD1047 as indicated)

7th July 2011, 09:51 PM	#1
Tenson diyAudio Member Join Date: Feb 2006 Location: Kent	Budget amp work-over :) I picked up this amp for my girlfriend for a total of £14. Now I know it is not perfect but I'm really impressed for the money, even when it was £60 new. Pictures on my forum here - AudioSmile Forum - View Single Post - Recommend me a girlfriend system So what do you guys think? Is it worth changing anything? I think I should up the smoothing caps from the 2x 2,200uF per rail but I'll have to see what fits. I'm uncertain how good the NE4558 op-amps are. I'm not someone who changes stuff because it isn't 'audiophile' so does anyone have distortion measurements for these? How is IMD? Worth changing for the lovely NE5532? Please post your comments on my forum if you like.

7th July 2011, 09:55 PM	#2
Tekko diyAudio Member Join Date: Jan 2005	Low budget indeed, the VBE multipliers dont even have thermal contact with the heatsink!!! That amp is guranteed to go into thermal runaway! __________________ The point of life is to build atleast one audio amplifier before you die.

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7th July 2011, 10:02 PM	#3
Tenson diyAudio Member Join Date: Feb 2006 Location: Kent	Thanks, I didn't notice that! I'll stick them on.

7th July 2011, 11:15 PM	#4
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	There is probably no point swapping the opamps as all the audio seems to go through these PT2314 Audio Processors That is a nice case though. You could probably build something better inside it in future

7th July 2011, 11:22 PM	#5
Tenson diyAudio Member Join Date: Feb 2006 Location: Kent	I'm not sure they are actually installed on the PCB. Obviously not on the top layer, I didn't look underneath but it doesn't look like 2-layer to me. Perhaps a precaution for the future? Does that look like leaking smoothing capacitors to you, on the main board? Or is it just a bit of glue?

7th July 2011, 11:29 PM	#6
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	They will be underneath, probably the SOIC versions of the chips. This can still be done on a 1-sided board. The black stuff is just glue. I'd say it's probably worth pulling those and fitting some good quality 4700uF capacitors. For £14 absolute bargain. Even for £60 it's good for the price of the case, heatsink, transformer and output transistors (assuming they are 2SB817/2SD1047 as indicated)

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