mounting RCA and speaker terminals on chassis

jaimango · 14th November 2007, 09:19 AM

These forums have been great for learning a lot about the topic of DIY audio, thanks everyone! This is my first post however, as I have not been able to find out about this simple question:

We are currently building a little chipamp from BrianGT. When mounting the RCA jacks and speaker terminals, do we have to make sure that they aren't actually touching the chassis somewhere? Or is it ok to have the signal ground touching the metal chassis? If they do have to be mounted without touching, what is the best way to do so? We are working with drilled aluminium panels here.

I know this may seem like quite a simple question, but I am quite new to this and I actually haven't been able to find out.

Thanks in advance.

Nordic · 14th November 2007, 10:16 AM

Signal grounds should be isolated from chassis or you'll get lots of hum.

Vikash · 14th November 2007, 10:37 AM

Welcome jaimango.

The jacks will come with two insulating washers (coloured plastic) which go either side of the panel and prevent the jacks touching the panel. The drilled holes should therfore be sufficiently sized.

jaimango · 19th February 2008, 09:11 PM

Thanks for all of your help, I'm happy to say no hums here.

In the end, the connectors I purchased didn't have any insulating washers; however I bought a multi-pack of plastic washers on ebay, and fit them to the back panel.

The threads on the connectors wouldn't fit (as the panel was 3mm Alu) but since it was so soft I just routed some washer sized holes through 1-2 mm and now it all fits together nicely.

Conrad Hoffman · 19th February 2008, 09:17 PM

For power amps I've successfully mounted the RCAs in the chassis, reasonably close together, with the chassis ground point right between them. The output connectors should never ground to the chassis. It won't work with phono preamps, but it might be possible with line stages. Not preferable, but possible.

AndrewT · 20th February 2008, 09:55 AM

Quote:

Originally posted by Conrad Hoffman
mounted the RCAs in the chassis, reasonably close together, with the chassis ground point right between them.

that seems like a practical work around.
Presumably the aluminium (not steel) needs to be clean and corrosion free.
Is the Safety Earth elsewhere?

jaudio · 20th February 2008, 11:47 AM

Quote:

Originally posted by Vikash
Welcome jaimango.

The jacks will come with two insulating washers (coloured plastic)

Where can I buy just the washers?

AndrewT · 20th February 2008, 11:54 AM

Hi,
the two washers need at least one with a step to prevent the RCA coming into contact with the chassis.
The washers need to suit the physical dimensions of the RCA socket thread and length. The hole in the chassis needs to match the washer step and not the thread diameter.
You might be able to use plain washers and an insulating sleeve, but this would be a once only fiddle that may perform just as well.

jb74 · 20th February 2008, 02:22 PM

http://mouser.com/

search for part # 561-SW25 (plastic shoulder washers I have used)

The online catalog page where that part is found will show
other washers as well

jaudio · 21st February 2008, 11:05 PM

Quote:

Originally posted by jb74
http://mouser.com/

search for part # 561-SW25 (plastic shoulder washers I have used)

The online catalog page where that part is found will show
other washers as well

Thanks

14th November 2007, 09:19 AM	#1
jaimango diyAudio Member Join Date: Oct 2007	mounting RCA and speaker terminals on chassis These forums have been great for learning a lot about the topic of DIY audio, thanks everyone! This is my first post however, as I have not been able to find out about this simple question: We are currently building a little chipamp from BrianGT. When mounting the RCA jacks and speaker terminals, do we have to make sure that they aren't actually touching the chassis somewhere? Or is it ok to have the signal ground touching the metal chassis? If they do have to be mounted without touching, what is the best way to do so? We are working with drilled aluminium panels here. I know this may seem like quite a simple question, but I am quite new to this and I actually haven't been able to find out. Thanks in advance.

14th November 2007, 10:37 AM	#3
Vikash diyAudio Moderator Emeritus Join Date: May 2003 Location: UK	Welcome jaimango. The jacks will come with two insulating washers (coloured plastic) which go either side of the panel and prevent the jacks touching the panel. The drilled holes should therfore be sufficiently sized. __________________ "The human mind is so constituted that it colours with its own previous conceptions any new notion that presents itself for acceptance." - J. Wilhelm. (But I still think mine sounds better than yours.)

20th February 2008, 11:54 AM	#8
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, the two washers need at least one with a step to prevent the RCA coming into contact with the chassis. The washers need to suit the physical dimensions of the RCA socket thread and length. The hole in the chassis needs to match the washer step and not the thread diameter. You might be able to use plain washers and an insulating sleeve, but this would be a once only fiddle that may perform just as well. __________________ regards Andrew T.

20th February 2008, 02:22 PM	#9
jb74 diyAudio Member Join Date: Oct 2004 Location: midwest	plastic washers http://mouser.com/ search for part # 561-SW25 (plastic shoulder washers I have used) The online catalog page where that part is found will show other washers as well

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14th November 2007, 10:16 AM	#2
Nordic diyAudio Member Join Date: Sep 2005	Signal grounds should be isolated from chassis or you'll get lots of hum.

19th February 2008, 09:11 PM	#4
jaimango diyAudio Member Join Date: Oct 2007	Thanks for all of your help, I'm happy to say no hums here. In the end, the connectors I purchased didn't have any insulating washers; however I bought a multi-pack of plastic washers on ebay, and fit them to the back panel. The threads on the connectors wouldn't fit (as the panel was 3mm Alu) but since it was so soft I just routed some washer sized holes through 1-2 mm and now it all fits together nicely.

19th February 2008, 09:17 PM	#5
Conrad Hoffman diyAudio Member Join Date: Mar 2007 Location: Canandaigua, NY USA	For power amps I've successfully mounted the RCAs in the chassis, reasonably close together, with the chassis ground point right between them. The output connectors should never ground to the chassis. It won't work with phono preamps, but it might be possible with line stages. Not preferable, but possible.

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