star grounding with a seperate PSu

[Rafal]

Hi Folks,

I have already done a chipamp based on BrianGT's design with everything in one box but my transformer (400KVA) makes the whole thing vibrate when it is powered on.

I would like to, therefore, put the amps in a diferent box than the PSU. I am wondering however, if the star ground should be in the amp box or in the PSU, or if I should have 2 star grounds (one in the amp and one in the PSU and connect them.

Also, what is a good wire gauge to use for the umbillical cord?

Thanks,

Rafal

[Ropie]

Hi, you'd usually want to keep all star grounds as close to the amp as possible, so keep them in your amp case.

[Rafal]

Thanks,

That clears things up.

Cheers,
Rafal

[lineup]

Originally posted by Ropie
Hi, you'd usually want to keep all star grounds as close to the amp as possible, so keep them in your amp case.

hello ropie
star grounding in any amplifier, chip or transistor,
is important and the good way to go
that's what all them best audio guys keep telling us!

In this post
and the following, you will see how i arranged this
in one of my amplifiers
http://www.diyaudio.com/forums/showt...62#post1019762

here is an image with my
Star Ground Junction
http://www.diyaudio.com/forums/attac...amp=1159861199


enjoy da' good musica
like
lineup - webmaster of
http://lineup.awardspace.com/

[AndrewT]

Hi Lineup,
is that a pic of a star ground between the two smoothing capacitors?
Then that is the wrong way to do it!

The second pic shows the smoothing caps connected to the star ground via a wire link. That is much better.

I would solder an earth tag to each grounding wire and then bolt all the solder tags together.
One then has the opportunity to unbolt and re-oganise the order of the bolted connections to help reduce/eliminate hum and/or buzz and/or distortion. Yes the order does matter.

[Rafal]

Does anyone have a suggestion for a wire gauge / type for an umbilical cord? I'm using a 400VA transformer and the secondary voltage is 22V DC?

Thanks in advance,

Rafal

[AndrewT]

Hi,
if you adopt the RCRC philosophy, then the gauge that results in 0r1 over the whole length would be about right.
You may want to increase the 0v gauge to give 0r05.
This will need two stage smoothing.
The first C is high ripple capacity and the second C is high quality AND must supply all the short term current demand of the amplifier.