electric hum during XL-1s playback at DVinfo.net

Steve Siegel · May 6th, 2002, 08:26 PM

I notice in my XL-1s that there is a low-pitched electrical hum upon playback, that was not there with my XL-1. I am recording in 16 bit. Since the XL-1s is new, I had the opportunity to make a comparison. Footage recorded on the XL-1 was free of the background hum, which began exactly as footage from the XL-1s began, same tape, exactly consecutive footage, all played back on the XL-1s, same cables, same TV.
The hum is faint, but noticable. Is there any way to adjust settings to remove it?

Steve

Don Palomaki · May 7th, 2002, 04:02 PM

Using the on-camera mic? Same rcording setup and venue? Perhaps the mic mount screw was too tight, resulting in coupling of transport noise to the mic body.

If the footage is important, perhaps you can low-pass filter it out in post.

Steve Siegel · May 7th, 2002, 04:28 PM

Thanks Don,
I'll loosen the screw, even though it sounds like the famous repairman's suggestion to the housewife that she reverses the polarity in the appliance's plug. Looks like the low pass filter will be the way to go.

Don Palomaki · May 8th, 2002, 02:20 PM

Reversing the plug did make a difference with some of the older designs before all plugs were polarized. It was especially valuable with some of the transformer-less (AC/DC) designs.

Phil French · June 25th, 2002, 09:05 PM

A way of reducing hum in Final Cut Pro, that I found, was to use the hum filter set at 150 hertz with the first harmonic selected. The way I found this was by blowing up the graph of the audio clip and counting the cycles of the low level hum (which were 5) for 1 frame. Times 30 (fps) gave me 150 cycles per second or hertz. I selected the first harmonic and it cut the XL1s hum almost right out of my quiet forest and bird song clip, yet other sounds remained intact. I do a lot of quiet nature stuff and I do this automatically if I am forced to use the on board microphone.

May 6th, 2002, 08:26 PM	#1
Steve Siegel Major Player Join Date: Nov 2001 Location: Albuquerque, New Mexico, USA Posts: 839	electric hum during XL-1s playback I notice in my XL-1s that there is a low-pitched electrical hum upon playback, that was not there with my XL-1. I am recording in 16 bit. Since the XL-1s is new, I had the opportunity to make a comparison. Footage recorded on the XL-1 was free of the background hum, which began exactly as footage from the XL-1s began, same tape, exactly consecutive footage, all played back on the XL-1s, same cables, same TV. The hum is faint, but noticable. Is there any way to adjust settings to remove it? Steve

June 25th, 2002, 09:05 PM	#5
Phil French Regular Crew Join Date: Feb 2002 Location: Lousana, Alberta, Canada Posts: 146	A way of reducing hum in Final Cut Pro, that I found, was to use the hum filter set at 150 hertz with the first harmonic selected. The way I found this was by blowing up the graph of the audio clip and counting the cycles of the low level hum (which were 5) for 1 frame. Times 30 (fps) gave me 150 cycles per second or hertz. I selected the first harmonic and it cut the XL1s hum almost right out of my quiet forest and bird song clip, yet other sounds remained intact. I do a lot of quiet nature stuff and I do this automatically if I am forced to use the on board microphone. __________________ Nature Boy

May 7th, 2002, 04:02 PM	#2
Don Palomaki Wrangler Join Date: Sep 2001 Location: Northern VA Posts: 4,487	Using the on-camera mic? Same rcording setup and venue? Perhaps the mic mount screw was too tight, resulting in coupling of transport noise to the mic body. If the footage is important, perhaps you can low-pass filter it out in post.

May 7th, 2002, 04:28 PM	#3
Steve Siegel Major Player Join Date: Nov 2001 Location: Albuquerque, New Mexico, USA Posts: 839	Thanks Don, I'll loosen the screw, even though it sounds like the famous repairman's suggestion to the housewife that she reverses the polarity in the appliance's plug. Looks like the low pass filter will be the way to go.

May 8th, 2002, 02:20 PM	#4
Don Palomaki Wrangler Join Date: Sep 2001 Location: Northern VA Posts: 4,487	Reversing the plug did make a difference with some of the older designs before all plugs were polarized. It was especially valuable with some of the transformer-less (AC/DC) designs.