Philip Perkins

Maxx+Nomad users: question re notch filer

21 posts in this topic

You folks using the Zax recorders--are you finding those built in notch filters handy?  Is the width and Q of the filter fixed (from the manual it seemed like it was)?  Is the width narrow (or wide) enough to be generally useful?  When you deploy it, is the post-filtered audio going to the iso track or just to the mix?  And can the filter "go the other way", ie be a boost?  Sorry if this is all in the manual--I didn't find this info.  Thanks!

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I've used the notch filters a few times, for AC, or computer whine / noise mostly. It's narrow enough not to interfere with dialogue. When I've had time to implement it, it has been great, to get rid of noise that can't otherwise be dealt with.

I've never seen a menu choice to vary it, that would mean variable components / hardware wouldn't it?

Think it's at an early stage on the input so goes to the iso?

From http://www.sengpielaudio.com/calculator-cutoffFrequencies.htm

looks like it might be about 10Hz each side of centre with a Q of 9.9?

Q-calc.jpg

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I don't have the numbers either but I do use the notch filters (two per channel) a lot and am quite impressed by their quality. I never heard any influence to my signal aside from removing the hum or whine I wanted to remove. Compared to using software plugin eqs set to notch in post I find the Nomad notches' effect very effective and good sounding. All you can set is the frequency, nothing else. They must be quite narrow. Don't do much on broader noise sources frequencywise. And yes, they affect tracks both pre and post fader.

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Thanks.  So they really are targeted slices for pitched BG sounds, and only cuts.  I assume they are in the moni chain so you can solo the channel and sweep the center freq up and down to find the sweet spot?

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Phillip, This isn't exactly what you asked, but, I use the 2k filter on the transmitters. That works great, when I use a particular set of lav mics. I managed to get an upper level manufacturer person, after much aggravation and stalling, to tell me they "didn't ground the capsule end" of the mic. So, I use that trans 2k filter for that, so get rid of non-grounded capsule end induced noise. I will try, when I get a chance, to try using the mixer filter for this and see what happens. 

I can see why the op would talk about the manual, I will say, the manuals could use improving for Zaxcom. I will leave the analogies out, so I won't  offend anyone. Ok, I can't stop myself. Brace for incoming analogy. The Zaxcom manual, in some parts, reads like a car driving manual that talks about how the car was designed and functions, and the like, but you have to have a manual that is written by someone driving the car and not the person that engineered it. 

I actually make notes on the pdf so I can be prepped if I need to look something up. 

Sorry I can't better answer your notch question at this point.

Sincerely, Martin 

 

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I will leave the analogies out, so I won't  offend anyone. Ok, I can't stop myself. Brace for incoming analogy.

The thing is, the analogy in this case and in most others is completely redundant. Maybe you under-estimate your ability to get your point across, but it's perfectly clear what you meant above without the analogy. Especially here everyone will understand the issues you had (and will be able to relate to them) with the manual.
By your use of analogy you seem like you are talking to a child - or like you are the child yourself. As if you are assuming that the reader won't comprehend what it is you are trying to say without your analogy.
The fact that your analogies frequently are off mark adds to the problem.
If you don't see why that can be annoying, I am sorry.

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Hi

I did a quick test, recording white noise from Pro Tools to 2 analog inputs (3&4) on the Nomad. Input 3 was unfiltered while Input 4 had the low pass at 80hz, and a couple of random notches at 400hz and 1Khz. I then put the two tracks together and loaded them into RX5 to look at the Spectrum Analyser. White is the unfiltered track, yellow the filtered/notched track. Interesting that the higher 1Khz notch has more reduction. Anyway, not a thoroughly rigorous scientific test, but useful as a general guide. I hope this helps!

Alistair

Nomad Filter Test.tiff

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18 hours ago, Philip Perkins said:

Thanks.  So they really are targeted slices for pitched BG sounds, and only cuts.  I assume they are in the moni chain so you can solo the channel and sweep the center freq up and down to find the sweet spot?

yes, you can totally do a sweep and monitor the notch, but it takes some practice, as the frequency moves linear as opposed to logarithmically, so the higher up you go the longer it takes. On my (and maybe others') request now you can press the menu button while turning, then the frequency will move in larger steps (50 instead of 5 Hz I think). But you can also dial in a random frequency number that you suspect a noise in, and go from there, which is what I do. I have an app on my phone that I use when I'm not sure what frequency I might be dealing with (I'm not one of the guys that are like 'yup, 745 Hz.') which is a bit quicker than just with the Nomad, as you can't "invert" the notch on the Nomad.

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The plot was very helpful, thanks.  I was sorry to hear that you can't invert the notch on the Max--that's how I usually work in the studio, but on the other hand it's semi-amazing that the notch filters are in the recorder at all.  Cool that you can invert on Nomad.

 

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I use the notch filters on occasion, and am very happy to have them when I do.  They are very transparent and effective.  It would be nice if the sweep was logarithmic, but typing in a starting frequency to sweep from works ok.  A notch boost option would be cool.

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I hadato rip off a 8000hz lightning hiss today and it was a pita with my maxx, much too long when director went to shoot itw on the fly...

A good option would  be to have the possibility to enter a frequency around suspect noise with keyboard and then affinate properly with dial, or another key to allow 100hz move, just sayin...

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it was a no post project and as long as have a notch option, make it useable ;)

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On 12/26/2016 at 7:40 PM, MartinTheMixer said:

I use the 2k filter on the transmitters. That works great, when I use a particular set of lav mics. I managed to get an upper level manufacturer person, after much aggravation and stalling, to tell me they "didn't ground the capsule end" of the mic. So, I use that trans 2k filter for that, so get rid of non-grounded capsule end induced noise. I will try, when I get a chance, to try using the mixer filter for this and see what happens. 

I am unclear why you would not just replace the mics.

Al

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Just now, al mcguire said:

I am unclear why you would not just replace the mics.

Al

AL, replace them with what?

Sincerely, Martin 

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Mics that had a "grounded capsule" and did not require a 2k notch filter

 

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Just now, al mcguire said:

Mics that had a "grounded capsule" and did not require a 2k notch filter

 

AL, Because it's a lot easier and cheaper to overcome the mic manufacturers missteps by flipping a switch than it is to buy a lot of mics.

Sincerely, Martin 

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On 1/6/2017 at 7:08 PM, zerascal said:

I hadato rip off a 8000hz lightning hiss today and it was a pita with my maxx, much too long when director went to shoot itw on the fly...

A good option would  be to have the possibility to enter a frequency around suspect noise with keyboard and then affinate properly with dial, or another key to allow 100hz move, just sayin...

You can already do that.

You can punch in the the exact frequency by using the keys on the front panel - just the same way you would punch in numbers when entering the tc or date.

Or as an option - which I use - is if you push in the menu knob as you rotate you move in 10Hz increments vs 1Hz by just rotating. I will use my index finger to push on the menu knob and rotate the knob with my thumb and middle finger as I listen. When I get to the point where I want to be I will release my index finger and just rotate in one Hertz increments to fine-tune.

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Invert notch filter option is what I want to recommend to Zaxcom. I'm thinking of making a cable from Nomad's output to my Smartphone to better using frequency analyzer apps.

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12 hours ago, Jack Norflus said:

You can already do that.

You can punch in the the exact frequency by using the keys on the front panel - just the same way you would punch in numbers when entering the tc or date.

Or as an option - which I use - is if you push in the menu knob as you rotate you move in 10Hz increments vs 1Hz by just rotating. I will use my index finger to push on the menu knob and rotate the knob with my thumb and middle finger as I listen. When I get to the point where I want to be I will release my index finger and just rotate in one Hertz increments to fine-tune.

It's what I do too, but I find it quite fumbly and sometimes unexpected things happen when pushing the menu button to turn. A logarithmic scale would be the most elegant solution for sure, as 1 Hz steps are really useless when I try to notch out, say, a hiss between 9000 and 11000 Hz. There, pressing the menu button and turning for 100 clicks will move the freuqnecy by 1000 Hz, which is very unelegant. Just saying, since I find the Nomad to be very elegant in general, except in this instance.

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On Sunday, January 08, 2017 at 3:23 AM, Jack Norflus said:

You can already do that.

You can punch in the the exact frequency by using the keys on the front panel - just the same way you would punch in numbers when entering the tc or date.

Indeed!!! Thx jack :)

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