Amp casing..Wood or Metal

Reeler · 4th February 2011, 07:16 PM

My project involves 7 similar amps on one wooden foundation. (Maybe 5)

If I use totally wood how do I 'Earth' the project?

Advice invited.

MJL21193 · 4th February 2011, 07:28 PM

Hi,
The case itself, being an insulator, cannot be grounded but all exposed metal parts need to be connected to the safety ground.
You would need to be careful about how you wire them together, especially for grounding to avoid ground loops. Star to the main power supply caps is probably best. Planning and testing will go a long way.

Reeler · 10th February 2011, 04:10 PM

Quote:

Originally Posted by MJL21193

Hi,
The case itself, being an insulator, cannot be grounded but all exposed metal parts need to be connected to the safety ground.
You would need to be careful about how you wire them together, especially for grounding to avoid ground loops. Star to the main power supply caps is probably best. Planning and testing will go a long way.

MJL, thank you.

I sort of get the picture. Am I correct that the 'back panel' where all the external connectors are positioned should have a common earth to each DC current coming from the various caps following each bridge?

I will try to draw a diagram in pencil.

From my prospective; each of the 5 or 7 separate amps on the wooden board will have it's own AC/DC power unit.....separate number of capacitors and separate Bridge Rectifier.

If I take each (Black lead from each 5 transformers) earth into a "star" configuration and the take one lead from the "star" onto the back plate, (which will have all the speaker leads etc) then I will have "earthed" the total cabinet?

Nobody will get blown up? Right?

PS....I won't be doing any of this until I am satisfied on paper...so to speak.

Andy5112405 · 10th February 2011, 04:46 PM

You are better using connectors that do not use the back panel as a conductor, ie use insulated connectors.

Then connect the screens and earths and grounds to one single point in the amplifier, the STAR EARTH point. This is generally as close as possible to the common 0V of the PSU capacitors.

If you are using separate PSUs for each amp. then make one STAR EARTH point and connect all the 0V connections to it.

If there are too many use a small piece of copper to act as a "block" to connect all the 0Vs together.

Reeler · 17th February 2011, 01:43 PM

Learning, learning, always learning.

Thank you!

4th February 2011, 07:16 PM	#1
Reeler diyAudio Member Join Date: Aug 2004 Location: Now in Barcelona	Amp casing..Wood or Metal My project involves 7 similar amps on one wooden foundation. (Maybe 5) If I use totally wood how do I 'Earth' the project? Advice invited. __________________ Most folk have their ears painted on!

17th February 2011, 01:43 PM	#5
Reeler diyAudio Member Join Date: Aug 2004 Location: Now in Barcelona	Learning, learning, always learning. Thank you! __________________ Most folk have their ears painted on!

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4th February 2011, 07:28 PM	#2
MJL21193 Account disabled at member's request Join Date: Mar 2007	Hi, The case itself, being an insulator, cannot be grounded but all exposed metal parts need to be connected to the safety ground. You would need to be careful about how you wire them together, especially for grounding to avoid ground loops. Star to the main power supply caps is probably best. Planning and testing will go a long way.

10th February 2011, 04:46 PM	#4
Andy5112405 Banned Join Date: Nov 2006 Location: Torpoint	You are better using connectors that do not use the back panel as a conductor, ie use insulated connectors. Then connect the screens and earths and grounds to one single point in the amplifier, the STAR EARTH point. This is generally as close as possible to the common 0V of the PSU capacitors. If you are using separate PSUs for each amp. then make one STAR EARTH point and connect all the 0V connections to it. If there are too many use a small piece of copper to act as a "block" to connect all the 0Vs together.

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