shield or not shield???

Leolabs · 23rd July 2006, 03:51 AM

I have seen lots of Gainclone,with metal,wooden,plastic.........boxes.So does a Gainclone actually need shielding or not???

facundonu · 23rd July 2006, 04:40 AM

mine was in a plastic box, and a radio sounded on my speakers quite loud. i had to shield the box with some metal sheets to solve this problem. use a metal box.

neutron7 · 23rd July 2006, 06:30 AM

it depends where you live as well, i had an unsheileded that sounded great but occasionally taxis are near the funeral home that is close by. when they are there it got some loud interferance.

when i used a metal box i never hear it.

henry zhang · 24th July 2006, 09:25 AM

What's "Gainclone"?Thanks for any help!

Zero One · 24th July 2006, 09:37 AM

Heres an idea and one I have actually implemented, lots of metal boxes look pretty horrible and clearly a nice timber job can be much nicer.
So..
Build a box around your boards/p2p circuit using copper PCB board and then run a ground from the enclosure to the star earth point on the amp. This will kill interference issues and will also help to make the amp more unconditionally stable if you want to use lower gain designs etc.

Of course you must use good quality sheilded cables as well.

It will also help stop interference from the power cables within the case, though this would no doubt be very subtle. Overall although a lot of gainclones seem to work well as far as their owners are concerned but my experience is that attention to lots of little details including really good shielding makes for a much better sound and less troubles long term.

At the end of the day you could then use any outer box type you want and the PCD board solders together pretty easily and is quite cheap for the amount you will need.

Narcisse91 · 26th July 2006, 04:03 PM

I built power supply and amp all in one box. I planned on shielding the amp from the supply, but just out of curiousity, I tested with and without, and there was definitely noise coming from my supply. So if you have the supply near the amp, definitely shield that.

I am about a 1/4 mile from some AM transmitters. I found that out after building my amp. There is definitely AM noise all over my board. However, with a source connected, speakers connected, and the normal AC and DC grounds handled properly, it doesn't come through when music is playing. It is, however, contributing to noise when no source is connected.

The enclosure is made from some spare MDF I had floating around.

So there is definitely the risk of noise, but even in my case, where I know the noise is there, it is not audibly affecting the music.

BrianDonegan · 26th July 2006, 05:24 PM

I played with laminating aluminum to wood for a while. Seems to work well for RF shielding (I too live across from radio towers).

The example above is walnut with aluminum flashing (comes on a long roll from a home center) applied with contact cement. I then cut the wood (and aluminum) to size on the table saw/router/whatever.

Zero One · 26th July 2006, 10:46 PM

(So there is definitely the risk of noise, but even in my case, where I know the noise is there, it is not audibly affecting the music.)

I feel that while the noise may not be audible, it will/may be mixing with the content of the music and causing low level degradation of the sound quality, perhaps a grainy presentation to the treble or mushy bass or just a lack of crystal clarity, so in the end it is best to avoid it if possible, it may also make the amp more likely to oscillate under some circumstances.

Of course earthing is critical with many circuits and my experience with clones is that good earthing can make a huge difference to overall sound quality as does proper sheilding.

juma · 27th July 2006, 08:26 AM

Quote:

Originally posted by henry zhang
What's "Gainclone"?Thanks for any help!

Gainclone is a DIY copy of Gaincard amplifier. Study these sites:

http://www.geocities.com/rjm003.geo/...io/diy_gc.html
http://www.dogbreath.de/Chipamps/Gai...nCardCopy.html
http://www.pedjarogic.com/gc/index.html
http://myweb.tiscali.co.uk/nuukspot/...loneindex.html

Have fun !

Bassterror · 27th July 2006, 08:57 AM

Hi

I'm buiding an MFD case for my 7293 right now.

Quote:

lots of metal boxes look pretty horrible and clearly a nice timber job can be much nicer

That were my thoughts too. MDF is easy to handle, an with some experience from loudspeaker prokects, you can get a very nice finish.

I wonder if RF interference cant't be eliminated with a simple high-pass-filter?

Have you tried alumineum foil from the kitchen?

23rd July 2006, 03:51 AM	#1
Leolabs diyAudio Member Join Date: Dec 2004 Location: Bukit Mertajam	shield or not shield??? I have seen lots of Gainclone,with metal,wooden,plastic.........boxes.So does a Gainclone actually need shielding or not???

23rd July 2006, 04:40 AM	#2
facundonu diyAudio Member Join Date: Apr 2006 Location: buenos aires	mine was in a plastic box, and a radio sounded on my speakers quite loud. i had to shield the box with some metal sheets to solve this problem. use a metal box. __________________ old fashioned 3 way http://www.diyaudio.com/forums/showt...threadid=81723 small sub http://www.diyaudio.com/forums/showt...threadid=93185

26th July 2006, 05:24 PM	#7
BrianDonegan diyAudio Member Join Date: Dec 2004 Location: Rock Ridge	I played with laminating aluminum to wood for a while. Seems to work well for RF shielding (I too live across from radio towers). The example above is walnut with aluminum flashing (comes on a long roll from a home center) applied with contact cement. I then cut the wood (and aluminum) to size on the table saw/router/whatever. __________________ Twisted Pear Audio

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23rd July 2006, 06:30 AM	#3
neutron7 diyAudio Member Join Date: Dec 2003 Location: Toronto Canada	it depends where you live as well, i had an unsheileded that sounded great but occasionally taxis are near the funeral home that is close by. when they are there it got some loud interferance. when i used a metal box i never hear it.

24th July 2006, 09:25 AM	#4
henry zhang diyAudio Member Join Date: Jun 2006	What's "Gainclone"?Thanks for any help!

24th July 2006, 09:37 AM	#5
Zero One diyAudio Member Join Date: Apr 2006 Location: Goulburn NSW	Heres an idea and one I have actually implemented, lots of metal boxes look pretty horrible and clearly a nice timber job can be much nicer. So.. Build a box around your boards/p2p circuit using copper PCB board and then run a ground from the enclosure to the star earth point on the amp. This will kill interference issues and will also help to make the amp more unconditionally stable if you want to use lower gain designs etc. Of course you must use good quality sheilded cables as well. It will also help stop interference from the power cables within the case, though this would no doubt be very subtle. Overall although a lot of gainclones seem to work well as far as their owners are concerned but my experience is that attention to lots of little details including really good shielding makes for a much better sound and less troubles long term. At the end of the day you could then use any outer box type you want and the PCD board solders together pretty easily and is quite cheap for the amount you will need.

26th July 2006, 04:03 PM	#6
Narcisse91 diyAudio Member Join Date: Aug 2002 Location: NY	I built power supply and amp all in one box. I planned on shielding the amp from the supply, but just out of curiousity, I tested with and without, and there was definitely noise coming from my supply. So if you have the supply near the amp, definitely shield that. I am about a 1/4 mile from some AM transmitters. I found that out after building my amp. There is definitely AM noise all over my board. However, with a source connected, speakers connected, and the normal AC and DC grounds handled properly, it doesn't come through when music is playing. It is, however, contributing to noise when no source is connected. The enclosure is made from some spare MDF I had floating around. So there is definitely the risk of noise, but even in my case, where I know the noise is there, it is not audibly affecting the music.

26th July 2006, 10:46 PM	#8
Zero One diyAudio Member Join Date: Apr 2006 Location: Goulburn NSW	(So there is definitely the risk of noise, but even in my case, where I know the noise is there, it is not audibly affecting the music.) I feel that while the noise may not be audible, it will/may be mixing with the content of the music and causing low level degradation of the sound quality, perhaps a grainy presentation to the treble or mushy bass or just a lack of crystal clarity, so in the end it is best to avoid it if possible, it may also make the amp more likely to oscillate under some circumstances. Of course earthing is critical with many circuits and my experience with clones is that good earthing can make a huge difference to overall sound quality as does proper sheilding.

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