Hum reduction

Ken Lang · Post by **Ken Lang** » 4 May 2006 5:50 pm

I'm working on converting some reel to reel tapes to computer, using Cakewalk. The first tape of myself and frieds is nearly 50 years old. The problem is the output volume is so low I've had to go thru a couple devices to boost gain. The hum is quite loud and I'd like to be able to reduce it.

I've done a search here but not downloaded anything yet. The threads reflect programs to do the taping, but I've not seen anything for reducing or getting rid of hum. Again the hum is from the equipment, not the tape itself.

Anyone have some concrete suggestions about hum reducing software?

David Doggett · Post by **David Doggett** » 4 May 2006 9:14 pm

Try an Ebtech Hum Eliminator. It's hardware, not software. But it might help.

Russ Wever · Post by **Russ Wever** » 4 May 2006 10:31 pm

Cool Edit has, in its effects, a filter that will read a 'profile' of the noise you want removed, then filter that 'profile' from the complete wave (or any portion you select).

Perhaps Cakewalk has something comparable in its filtering effects, or there's a 'plug in' available.

~Russ

Dave Potter · Post by **Dave Potter** » 5 May 2006 4:16 am

I think it's relevant to ask where the hum comes from - is it part of the audio on the tape, or is it being introduced by the devices used "to boost gain"?

George Kimery · Post by **George Kimery** » 5 May 2006 5:12 am

What would happen if you run it through a parametric equalizer and dial in the 60 cycle hum, or whatever the frequency of the hum is, then using the equalizer, cut at the hum frequency? This is just an idea that popped into my head. I am not proficient in these things, so keep that in mind.

John Daugherty · Post by **John Daugherty** » 5 May 2006 5:35 am

Ken, it is important to turn up the playback recorder gain as high as possible so your signal level will be louder that any hum that is introduced by the amps. If this introduces more hum, the hum is coming from the recorder.
You should clean and demagnetize the recorder heads first.
It is possible that a ground loop is causing the problem. If your preamps have 2-wire AC line cords, try reversing them in the wall receptacle. If they have 3-wire plugs, try a 3-wire to 2-wire adaptor.
You have probably tried another audio cable. If not, do it. I have found several bad audio cables in my experience.
I don't know why you need preamps. You should have enough signal from the recorder to go directly to the computer line-in.
You must first determine where the hum originates, in order to eliminate it.

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www.home.earthlink.net/~johnd37

Brad Sarno · Post by **Brad Sarno** » 5 May 2006 6:04 am

George. Hum is not as simple as 60Hz. If you were to remove or reduce 60Hz, you'd also be removing the music at that frequency. Also hum has overtones as all tones do. 60Hz may be the fundamental tone of hum, but 120Hz is quite often as strong, and then there are also the overtones that continue on up the series. EQ is more of a last resort when it comes to hum fixing. It's best to nail down exactly where the hum is coming from and then address that issue. It could be the cabling causing a hum loop. It could the the tape heads are near a strong hum field. Sometimes just turning a tape machine can tame it down if that's where it's coming from. You know like with a single coil pickup in a guitar how you can turn the guitar and find the null zone where the hum goes away. Really the hum could be from a number of places. Proper levels coming from the tape machine are also important. If you're getting a weak signal from the tape machine and are trying to make up the gain elsewhere, that could also increase the hum problems.

Brad

George Kimery · Post by **George Kimery** » 5 May 2006 6:16 am

Thanks Brad for enlightening me on the hum vs. equalizer issue. I really hadn't thought about hum having overtones and that you would be killing any music at the same time. Also, I would like to put in a plug for your black box. It is simply great and I would hate to have to go back without it.

Robert Leaman · Post by **Robert Leaman** » 5 May 2006 6:47 am

You might try increasing the audio level in Cakewalk by using the "Normalize" instead of trying to increase audio level with preamps. There is no known preamp that neither adds nor subtracts from an input signal.

Ken Lang · Post by **Ken Lang** » 5 May 2006 9:36 am

As I mentioned, the hum is equipment, not in the tape. Cakewalk has nothing to improve that. I've tried EQ etc but nothing helps. The Ebtech unit is for ground fault hum. Normalizing increases the hum as well as the sound.

I downloaded the trial version of Cool edit's RipEditBurn and record cleaner software but it doesn't work very well for my hum conditions.

For what I'm doing with this tape I believe I'll live with the hum for now. Hopefully other tapes will have more volume.

Thanks for all your help.

Larry Clark · Post by **Larry Clark** » 5 May 2006 10:08 am

If you are using Cakewalk on a desktop computer with a CRT monitor you might be picking up noise from the monitor via the tape heads. Try turning off the monitor while the hum is present and see if things improve. If so move the tape deck as far away from the monitor as possible. Just a thought, Good Luck

Dave Potter · Post by **Dave Potter** » 5 May 2006 3:12 pm

I'd remove the "devices" from the signal chain, and digitize that way. Elevate the gain with whatever software you have available, at that point. "Hum" shouln't be a factor once it's all "ones-and-zeros", is the way I understand things.[This message was edited by Dave Potter on 05 May 2006 at 04:46 PM.]

Larry Clark · Post by **Larry Clark** » 5 May 2006 3:43 pm

I think it's relevant to ask where the hum comes from - is it part of the audio on the tape, or is it being introduced by the devices used "to boost gain"?

As I mentioned, the hum is equipment, not in the tape.

Did I miss something?

Ken Lang · Post by **Ken Lang** » 5 May 2006 8:28 pm

I made a CD for my brother-in-law, hum and all. It's livable for something that will rarely be listened to save a few times.

The second tape I loaded, from 1960, had no hum to speak of. All's well and hum is no longer a concern. Thanks. Ken