Applying Notch Filter ???

Hi, I hope it’s te right place to present my problem (i"m new to the forums)
anyway, here’s the problem:
I’m trying to activate NOTCH.NY in order to remove 50Hz electrical noise,
but despite the file exists in the PLUGINS folder, it’s missing from EFFECTS.
I obtain very good results in recording LP’s, with v.1.3.4, but the 50Hz noise
is pretty annoying.(desktop/P4 1.5G/512 RAM /XP PRO SP2 /HD 200 GB)
My turntable is a pulley-type LENCO B55 - Swiss made - in very good condition,
which has 78 rpm too, so I think it’s obvious why the 50Hz noise.
So I would very much appreciate if somebody could enlight the way
to putting the NOTCH FILTER into the EFFECTS menu.

Notch filter isn’t going to do it. You can barely hear “real” 50 Hz hum. What you’re hearing is 50 and the first six or eight harmonics; 100, 150, 200, 300, etc. I’m going to be really unpopular yet again suggest strongly you fix it before it’s broken.

Make sure the turntable audio cables are clean and firmly plugged into their sockets. Each turntable has a thin black grounding wire in addition to the audio leads. That is required to be connected to whatever you’re using as a phono preamp. Almost all phono preamps have a place for it.

Change the power plugs around. Everything in the audio chain must be plugged into the same circuit, or in some cases, wall socket. If something in the chain has a non-polarized plug, try flipping it over and plugging it in. I have an FM tuner that only works plugged into power in one direction. It hums the other way.

If it’s always done this, you may have bad wall power wiring. In the US, there is such a thing as a polarity tester. It’s a little plastic thing with three lights on it that you can plug into a wall outlet and see if it’s wired right. The right two lights have to come on. Typically, they’re US$10 or so. Radio Shack used to carry one.

If your sound system is connected to speakers, you can turn it up and listen while you wiggle cables and change things around. A properly operating turntable makes no noise when it’s not playing a record.


Here’s one. GRT-500A

Scroll down. It’s the yellow one. Some say it’s possible to get funny readings with these, but if you get an error condition, it’s almost 100% certain that there is a power wiring error. Adapt the idea to the power wherever you are.

Both of my old houses had wiring errors when I moved in, so I’m not making this up.


This is really a comprehensive one !
I’m going to do that overhaul-check, and report.
BTW, what is NOTCH.YM for?
A great thank, koz

My mistake, Imean NOTCH.NY


Nyquist laid down laws of digital sampling of analog signals, but I don’t think that has anything to do with the filters. Like most French people are horrified at the idea of French Fries.

I’d be googling this right now which you can do. I’m going to bed.


When you have minimized the hum as much as possible, if some hum still remains, the “Noise Removal” effect in Audacity 1.3.4 is probably the best tool to use.

Hum IS minimized:
Turntable ground=check
Equipment plugged to the same circle=check
Electr. polarity=check
I am doing fine with NOISE REMOVAL, BY THE BOOK!
My problem is with classical music, with very quiet parts, where the Noise Removal “kills” the music,
so I have to give up the noise removal.
I am using the default parameters, e.g. Noise Reduction (db): 24; Frequency Smoothing (Hz): 150;
Attack/decay time (secs): 0.15. Maybe I should change the defaults ???
The “HUM” I’m complaining about is rather weak, but is still there. Here is the screenshot at the ‘profiling’ stage:

Unless you have magnified the vertical scale, that still looks like quite a lot of hum, and complete removal may not be possible.

Make sure that you have a sample of hum that is COMPLETELY absent of any music (sample it before you put the stylus on the record). Try adjusting the noise reduction settings.

Are you using Audacity 1.2.6 or 1.3.4 - they have quite different noise removal effects - I usually prefer the one in Audacity 1.3.4, but occasionally (depending on the musical material and the kind of noise) find that the earlier one gives better results, so try both.