What can i build?

r0n22 · 2nd April 2009, 12:23 AM

Hey guys been trolling for awhile and just got up the guts to build my first chip amp.

I have a 150va with a 58 vct which means that I could have +/- 40 v rails? What could I use it for ?

I can use more than 1 transformer which means that I could have +/- 81.2 v rails?

I was thinking a lm4702 but is it a bit too low or too high?

What do you guys think that I could build?

Thanks in advance

-Cam

drummer_Dave · 2nd April 2009, 06:19 PM

i believe that's the max for TDA7293 (100W capable but if making a stereo Amp you wont get quite that high...)
you can also get some regulator's (LM338, LT1083 etc...and bring it down a bit
then you could use the lm3886 (68W chip, +/- 35 i think for 8 ohm)

or you can always wander over to the solid state crowd... with 80 volt rails you could really start doing some damage to speakers...

just my 2 cents

Dave

pacificblue · 2nd April 2009, 07:14 PM

If you use 8 Ohm speakers and invest in a good heatsink, you can run LM3886 from those transformers. The DC voltage will sag sufficiently to remain within the IC's specs, when loaded.

The TDA7293 or TDA7294 are a bit more demanding, when it comes to a good layout, while the LM3886 is quite forgiving in that regard.

The LM4702 is probably not a good choice for a first project. Even, if you make an exact copy of a proven project, you should have some experience in amplifier building. And you will need good and expensive measuring equipment, e. g. an oscilloscope, for the final tests before connecting a speaker to it.

Minion · 2nd April 2009, 09:49 PM

I use a 56v CT 200Va Transformer (Puts out +/-42v DC unloaded) with a TDA7293 in my DIY guitar amp , it works great and is freaking loud...
I just used the PCB design in the Datasheet and it worked fine , I bypassed the Anti-Turn on Thump feature so there is a small thump when you turn the amp on but it doesn"t bug me...

I also just bought a stereo or Bridged mono TDA7293 kit on e-bay , it was like $23 and comes with all the Parts and PCB for a Stereo amp board as well as a dual gang Conductive plastic pot...
He also sells PSU boards for like $5 that come with PCB and Bridge rectifier and terminal blocks but no filter caps but spaces for 4 large caps...

Check it out...

http://cgi.ebay.ca/TDA7293-Hi-Fi-Pow...1%7C240%3A1318[

Cheers

PS: he also has stereo LM3886 boards for about the same price..

2nd April 2009, 12:23 AM	#1
r0n22 diyAudio Member Join Date: Feb 2009	What can i build? Hey guys been trolling for awhile and just got up the guts to build my first chip amp. I have a 150va with a 58 vct which means that I could have +/- 40 v rails? What could I use it for ? I can use more than 1 transformer which means that I could have +/- 81.2 v rails? I was thinking a lm4702 but is it a bit too low or too high? What do you guys think that I could build? Thanks in advance -Cam

2nd April 2009, 07:14 PM	#3
pacificblue diyAudio Member Join Date: May 2008	If you use 8 Ohm speakers and invest in a good heatsink, you can run LM3886 from those transformers. The DC voltage will sag sufficiently to remain within the IC's specs, when loaded. The TDA7293 or TDA7294 are a bit more demanding, when it comes to a good layout, while the LM3886 is quite forgiving in that regard. The LM4702 is probably not a good choice for a first project. Even, if you make an exact copy of a proven project, you should have some experience in amplifier building. And you will need good and expensive measuring equipment, e. g. an oscilloscope, for the final tests before connecting a speaker to it. __________________ If you've always done it like that, then it's probably wrong. (Henry Ford)

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2nd April 2009, 06:19 PM	#2
drummer_Dave diyAudio Member Join Date: Oct 2006	i believe that's the max for TDA7293 (100W capable but if making a stereo Amp you wont get quite that high...) you can also get some regulator's (LM338, LT1083 etc...and bring it down a bit then you could use the lm3886 (68W chip, +/- 35 i think for 8 ohm) or you can always wander over to the solid state crowd... with 80 volt rails you could really start doing some damage to speakers... just my 2 cents Dave

2nd April 2009, 09:49 PM	#4
Minion diyAudio Member Join Date: May 2006	I use a 56v CT 200Va Transformer (Puts out +/-42v DC unloaded) with a TDA7293 in my DIY guitar amp , it works great and is freaking loud... I just used the PCB design in the Datasheet and it worked fine , I bypassed the Anti-Turn on Thump feature so there is a small thump when you turn the amp on but it doesn"t bug me... I also just bought a stereo or Bridged mono TDA7293 kit on e-bay , it was like $23 and comes with all the Parts and PCB for a Stereo amp board as well as a dual gang Conductive plastic pot... He also sells PSU boards for like $5 that come with PCB and Bridge rectifier and terminal blocks but no filter caps but spaces for 4 large caps... Check it out... http://cgi.ebay.ca/TDA7293-Hi-Fi-Pow...1%7C240%3A1318[ Cheers PS: he also has stereo LM3886 boards for about the same price..

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