Airpax hum/shielding against hum

planarboy · 13th August 2008, 05:37 PM

Whenever my MC cart goes near the airpax motor, it starts to hum, and at a higher frequency when its on 45, I have a hercules-alike power supply, two high voltage sinewaves I understand.
Sticking copper foil to the engine bay is a noted method, but how do I do it?
I don't know if it has to join something and does it have to be insulated from the motor.
I'm sure my problem can be fixed, I just know nothing much about shielding.
And I still want a second arm, the end of which will be near the motor all the time.
Definitely have to fix that before I cut that plinth.
The only thing left of my original planar is the motor itself and the brass bearing house.
Thanks if anyone can help.
dave
P.S. Also looking for a dead simple two channel stereo amp that i can eventually mod the hell out of before trading in for something real nice, would spend around 150 i guess...marantz? No idea, me.

tubenut · 13th August 2008, 09:06 PM

You say nothing is standard anymore. I assume the arm is rewired? Is there a solid earth to at least the base of the arm but ideally the tube?
I have used Planar 3 with various MCs from Linn and Audio Technica and never had a problem.

planarboy · 14th August 2008, 01:03 AM

yeh its solid earth to the back of the arm, incognito.
I've only had the hum problem since I got the power supply

YNWOAN · 14th August 2008, 01:29 PM

If you have not altered the motor position or the cartridge and if, as you say, you have only had the hum problem since you fitted the power supply, it is much more likely that the hum is the result of your cartridge moving over the power supply board. I suspect you have mounted this board under the plinth of your deck. I recommend that you move the position of said board.

planarboy · 14th August 2008, 02:07 PM

nah its in a box about 1 metre away..the original pcb rout doesnt exist in my plinth, just a hole big enough for the motor.

YNWOAN · 14th August 2008, 02:38 PM

Oh well, don't really know then - sorry. I can't think of a reason why just changing the PS should suddenly make the motor produce more interference.

planarboy · 10th November 2008, 12:30 AM

In the end I put some thickish copper foil tightly around the airpax motor and held it in place with the big rubberbands I got from SRM/Tech. Hey presto! Totally cured.
My system is quieter than ever......

13th August 2008, 09:06 PM	#2
tubenut diyAudio Member Join Date: Nov 2002 Location: South Africa, Jhb	You say nothing is standard anymore. I assume the arm is rewired? Is there a solid earth to at least the base of the arm but ideally the tube? I have used Planar 3 with various MCs from Linn and Audio Technica and never had a problem. __________________ Guillaume Croak Audio Exploration

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14th August 2008, 01:03 AM	#3
planarboy diyAudio Member Join Date: Jun 2007	yeh its solid earth to the back of the arm, incognito. I've only had the hum problem since I got the power supply

14th August 2008, 01:29 PM	#4
YNWOAN diyAudio Member Join Date: Jan 2007	If you have not altered the motor position or the cartridge and if, as you say, you have only had the hum problem since you fitted the power supply, it is much more likely that the hum is the result of your cartridge moving over the power supply board. I suspect you have mounted this board under the plinth of your deck. I recommend that you move the position of said board.

14th August 2008, 02:07 PM	#5
planarboy diyAudio Member Join Date: Jun 2007	nah its in a box about 1 metre away..the original pcb rout doesnt exist in my plinth, just a hole big enough for the motor.

14th August 2008, 02:38 PM	#6
YNWOAN diyAudio Member Join Date: Jan 2007	Oh well, don't really know then - sorry. I can't think of a reason why just changing the PS should suddenly make the motor produce more interference.

10th November 2008, 12:30 AM	#7
planarboy diyAudio Member Join Date: Jun 2007	In the end I put some thickish copper foil tightly around the airpax motor and held it in place with the big rubberbands I got from SRM/Tech. Hey presto! Totally cured. My system is quieter than ever......

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