TDA 2040/LM3876 Amplifier

[madmodder]

Hi Everyone.
This is my first post in diyAudio

OK a number of years ago I was given three B&O tv's and managed to fix 2 of them and sold them both. I scrapped the third, taking the audio amp section out first
Fast forward 10 years and one of the TV's only just failed! So I took the Amp out of that too!
Now, why you ask?
Well the audio amps are based on TDA2040 (sigle supply version)
I going to make either a bi-amp setup or use them bridged to drive my B&O CX50's (£5 at a bootfair ) along with the LM3876 to drive a small sub.
This is all being done on a shoestring budget and is taking ages!
The amp will also have Digital input (CS8416\TDA1545 with reclock)
I used eagle to make the 2040's and the heatsinks are old CPU coolers
The case is going to be difficult and I'm looking for inspiration but I reckon wood is going to be the way forward (so my better half likes the way they look)

Just thought I'd share my project with you all...

[simply14prem]

Just as a hobby I have constructing a TDA 2040 amp with split power supply .Im using 20-0 -20 transformer ,Im getting +15v,-15,But Im not getting any sound yet .Do i need a pre amp ?I want to connect to DTH {sattelite reciever}audio output .Thank u

[pra3718]

Im using 20-0 -20 transformer ,Im getting +15v,-15,

you mean you are using 20-0-20 transformer and you are getting 15VDC (+/-) then your calculation is wrong.

[AndrewT]

or he doesn't know how to set and read his DVM.

~15Vac (open circuit) would give ~20Vdc (open circuit) after rectifying and smoothing.

[pacificblue]

Originally Posted by madmodder

The case is going to be difficult and I'm looking for inspiration but I reckon wood is going to be the way forward

You can always make fine looking amps with wood. Some people even swear that amps in wooden enclosures sound better. I have my doubt about that, because a wooden enclosure has no shielding effect agains EMI, but that is a different story.

I have always thought to give modelling compound a try for a case. Here in Germany they sell polymer clay by the name of Fimo. It gives a clean finish, is available in many colours, leaves a lot of freedom to decide on the shape and should be easy to drill. It will however take a few attempts until you get the dimensions right, because it shrinks during the hardening process. There are version that harden after 24 hours contact with air, others need to be hardened at 110 °C in the oven and some can even be hardened in a microwave oven. Never got around to try it myself, though.