Audio Technica AT897 with small consumer grade low end DVR

[Syed Junaid]

I want to record the speech in acoustically live environment. Speaker will be within 8" from Mic. I will record it in a Hall, which isn't acoustically engineered, it has many ceiling fans, several pillar, and a net of Speaker for sound reinforcement. Because cardioid mic has low off axis rejection, therefore I will use the shotgun or line-cardioid to reject the all unwanted noise of fans etc.

Do you think shotgun won't help me? I saw many videos no YouTube in which cardioid or Omni mic picking up so much ambient noise. There is a complete PA system, but I want to recorder through my own chain, i.e. Audio Technica AT897 -->??? -> Sony Digital Voice Recorder ICD-UX200.

I'll sync it with still photos. Hence sync won't bother me, it is like a slide show with a voice track.
I will patch XLR Mono Balanced to TRS Stereo unbalanced 1/8” like this:

XLR Pin 1 to unconnected
XLR pin 2 to Mini Jack tip and ring
XLR pin 3 to mini-jack sleeve

I'm a newbie; therefore I asked so many questions, any advice from you guys is very worthwhile for me, Sorry for my bad English.

1) How do I know if my DVR has plug-in power DC voltage? If DC blocking is inevitable, then what value of volt should I use for the capacitor? As well as the link below suggesting me that I can use this same capacitor to roll off low frequencies and it depends upon the value of µf which should lies b/w (1 to 5). I want to roll off sound frequency below 80Hz then what value of µf should I use for the capacitor. However my DVR has Low cut filter and Noise-Cut function also my mic has integral 80 Hz high-pass filter, then do I really need this capacitor rolling off?

Camcorder Mic Adapters


2) My DVR doesn’t have manual recording gain control; it has only three sensitivity setting: S-High, High, and Low and it has minimum input level of 0.9 mV and AT897 has Nominal open circuit output voltage of 8.9 mV (battery) at 1 V, 1 Pascal, then Do I need an attenuator?

ICD-UX200: Recorder Microphone jack input for plug in power has minimum input:
level 0.9 mV, 3 kilohms or lower impedance microphone.

AT897:
Element Fixed-charge back plate, permanently polarized condenser
Polar pattern Line + gradient
Open circuit sensitivity Battery: –41 dB (8.9 mV) re 1V at 1 Pa
Impedance Battery: 300 ohms
Maximum input sound level Battery: 115 dB SPL, 1 kHz at 1% T.H.D.
Dynamic range (typical) Battery: 98 dB, 1 kHz at Max SPL
Battery type 1.5V AA/UM3
Battery current / life 0.4 mA / 1200 hours typical (alkaline)
Output connector Integral 3-pin XLRM-type

Spec. Sheets:
http://www.docs.sony.com/release/ICDPX820.pdf
http://www.docs.sony.com/release/ICDUX200.pdf
http://www.audio-technica.com/cms/re...897_submit.pdf

[Steve House]

The voltage rating of the blocking capacitor is not important, anything around 10 volts or so should be fine.

How do you know if your DVR has plug-in power on the mic input? It says it does right in the specs you quoted. "ICD-UX200: Recorder Microphone jack input for plug in power ..."

1 Pascal is an indication of sound pressure and a 1 Pascal sound is very loud, approximately 94dB SPL. In contrast, normal day-to-day conversation is about 60dB SPL while a jack hammer @ 1 metre is about 100dB SPL. How much voltage your mic will actually be putting out depends on how loudly the person speaking is projecting their voice. Your DVR specs on the other hand are calling for a minimum input voltage and they don't say how much over that it can go without distorting or clipping. So at this point there is insufficient information to say whether you'll need an attenuator or not. The only thing you can do is try it (before the day you need to record the real speech) and see what happens.

Don't expect the shotgun to completely eliminate the noise from the ceiling fans, etc. Shotguns have LOWER sensitivity to sounds off-axis than to sounds on-axis but it is a relative thing. They still pickup SOME sound from all directions, just they pickup LESS from directions other than where they're pointed. And that directionality is frequency dependent ... pretty pronounced in the range of voice frequencies but tending to get almost omni in response at lower frequencies (such as the whump whump whump of fans, for instance). And when the reflections of the speaker's voice coming off the walls and pillars, not to mention the PA, hits the shotgun, they'll interact with the direct sound and it will probably sound like the speaker is talking in a cave.

[Syed Junaid]

Thank you for all, AT897 is working in ICD-UX200.I patched XLR Mono Balanced to TRS Stereo unbalanced 1/8” like this:
XLR Pin 1 to unconnected
XLR pin 2 to Mini Jack tip and ring
XLR pin 3 to mini-jack sleeve.
• I used 4.7 µf non-polar 50V capacitor between XLR pin 2 and mini jack tip/ring
• I didn’t match their impedances (AT896 = 300Ω and UX200 = <3000Ω). Guys me that told impedance was Ok.
• I didn’t use any attenuator or preamp.
• Recorder’s Low Cut filter is on
• I record it at “ST” High-quality stereo recording mode (44.1 kHz/192 kbps)
• Recorder was set to “High” sensitivity however “high” is undesirably High and low is too much low, as you have told me before
• Microphone 80Hz filter is on
• Mic is almost ½ feet away from me
• I record it in Room (12’x10’x10’) with Furniture

My problem is that why it is creating hiss. How I get rid of hiss from recoding?:
• Is it capacitor problem (i.e. 4.7 µf non-polar 50V)
• Is it impedance mismatch

Or if there is nothing wrong in above two things then which is best software to denoise this type of hiss:
• iZotope RX
• Wave lab 7 or something else

I’m complete novice. I mistakenly download Cubase 5 but it doesn’t have any denoiser.

Please check my hiss test:
YouTube - AT897 Hiss Problem with Sony ICD-UX200

[Rick Reineke]

"XLR Pin 1 to unconnected' ???

1. XLR Pin 1 should be connected to the 'shield' of a short good quality shielded mic cable, at the other end, connect the cable's 'Shield' to the 3.5mm mini-plug's sleeve/ground.
2. Hiss can be attenuated by using a Low-pass/ High-cut EQ filter, starting at around 10kHz. t
3. The cheap version of "Sound Soap" can attenuate the hiss further.
4. Use the money saved on expensive NR app.s to purchase an audio recorder and/or camera with XLR inputs and manual gain control.

1. Fact
2. Fact
3. Fact
4. Opinion

(Do not confuse "Attenuate" with 'Remove'.

[Syed Junaid]

1. No, not necessary b/c have isolated system just DVR, Mic and just 3 meter unshielded cable i.e. NO RFI interference. As well as someone told me that If connect XLR 1 to sheild with this type of mono to stereo connection then I should not use this in Phantom power, otherwise something will go wrong. Am I right?

2. I'm sorry I novice, didn't understand, I already enabaled recorder's Low-cut filter and mic's 80 Hz filter. Are you telling me that I use "Low-pass/ High-cut EQ filter" in software mode? I'm downloading iZoptop RX, is this software has "Low-pass/ High-cut EQ filter"?

4. I have already purchased these things.

[Rick Reineke]

The shield should always be connected at both ends for microphone cables.

"Phantom Power" can only be used or available in recording devises having the XLR / balanced input configuration. "Plug-in power' is a low voltage 'bias current' and eliminates the need of battery power. (on some mics). Since your obviously using the mics internal battery power, that's why you need the blocking capacitor to negate the low voltage bias current. (aka, Plug-in power©. (which is a copyrighted term. (Sony I think), as is the term "Phantom Power" invented by Neumann.

The 3.5mm mini-plug's tip and ring are tied together to feed both L&R channels the same signal.

And yes, XLR's pin-1 and pin-3 are normally tied together for unbalanced operation, though in some instances, pin-3 is not connected. I would check the mic's manual to be sure for unbalanced operation.

Microphones and recorders rarely have a high-cut filters.

[Syed Junaid]

XLR Pin 1 to unconnected
XLR pin 2 to Mini Jack tip and ring
XLR pin 3 to mini-jack sleeve.
• I used 4.7 µf non-polar 50V capacitor between XLR pin 2 and mini jack tip/ring

Tip isn't connected to sleeve or ground or shield, you mixed connections completely. Please visit:

Camcorder Mic Adapters

You didn't elaborate on "Low-pass/ High-cut EQ filter".

[Rick Reineke]

Your're right, the blocking cap. is in series on pin -2 or tip.
"Tip isn't connected to sleeve or ground" It shouldn't be, that would short out the signal all together.

Please clarify what you mean by "XLR Pin 1 to unconnected"
As I stated, this must be connected the cable shield

"You didn't elaborate on "Low-pass / High-cut EQ filter" Different terms, also known as, but do the same thing.
"High-cut" filter, also known as, "Low-pass filter": Attenuates high frequencies, (Hiss for instance) Low frequencies pass though unaffected.
"Low-cut filter", also known as "High-pass filter: Attenuates low frequencies. ( Rumble for instance) High frequencies pass though unaffected.
EQ= Frequency Equalization
Hope this helps.

[Syed Junaid]

If I connect XLR 2(in-Phase) to ground/Sleeve and XLR 3(out-of-Phase) also connected to ground/sleeve then XLR 2 and XLR 3 will cancel out each other due to phase difference!

b/c I have isolated system just DVR, Mic and just 3 meter(I think it is too short to get RFI) unshielded cable i.e. NO RFI. Hence I left XLR 1 unconnected, it wasn't connect to shield. However I was advised as "the shield is connected to pin 1 at the XLR end but left floating, not connected to anything, at the TRS end."

Do you think I can make "Low-Pass Filter" using same voltage blocking Capacitor? as it is advised in
Camcorder Mic Adapters and
Opamp Labs Inc <> RFC Calculator <> www.opamplabs.com

But couldn't understand what is the meaning of "you want frequency response down to 20 Hz, then you would use a 3.18 microfarad capacitor" in above mentioned link

What is the meaning to "down to 20 Hz", is it means below 20Hz (19, 18, 17, ....) OR till 20 Hz (....,22,21,20)? I'm sorry English isn't my native language.

[Steve House]

Originally Posted by Rick Reineke

...Please clarify what you mean by "XLR Pin 1 to unconnected"
As I stated, this must be connected the cable shield

...

XLR pin 1 should be connected to cable shield, true. This extends the mic's case shield all the way to the recorder. But the cable shield can be left 'floating' at the TS/TRS end, connecting the conductor from XLR pin 3 to TRS sleeve/ground and leaving the shield unconnected. See these "Rane Notes" technical papers on balanced to unbalanced connections and the "pin 1 issue."

Sound System Interconnection cable diagram # 5 or 6.
Pin 1 Revisited
Grounding and Shielding Audio Devices

Connecting the cable shield to audio signal ground at the recorder end sends any hum or interference hitting the cable directly into the audio circuits. The recorder's plastic case is not a shield and the TRS sleeve is going to audio ground, not a case shield. If the recorder case was a shielding enclosure and the input was balanced it might be a different story.

[Richard Crowley]

Originally Posted by Syed Junaid

But couldn't understand what is the meaning of "you want frequency response down to 20 Hz, then you would use a 3.18 microfarad capacitor" in above mentioned link.

I am the author of the page you are asking about. What I meant was that assuming a 2500 ohm input impedance (which you don't really know without measuring it), using a 3.18uF capacitor will give you a 3dB rolloff at 20Hz. That means that the low-frequency response will curve down and the response will be 3dB down at 20Hz.

For example, this diagram shows the 3dB down point at around 42 Hz...
http://www.ajdesigner.com/images/spe...quency_bak.png

[Syed Junaid]

Ok Thank you.

1) If I want to roll off ≤80Hz (audio frequency) to 3dB then I should use 0.7uf capacitor a/c to your formula?

2) But If I want to roll off high frequency (Hiss) then is this formula applicable?

3) what is the value of Hiss in Hz in this audio:

http://www.youtube.com/watch?v=SGpvyZCxPzc

[Richard Crowley]

1) If I want to roll off ≤80Hz (audio frequency) to 3dB then I should use 0.7uf capacitor a/c to your formula?

Yes, ASSUMING that you have a 2500 ohm input impedance.
REPEATING: YOU DON'T KNOW WHAT YOUR INPUT IMPEDANCE IS, SO THIS FORMULA IS OF LIMITED USEFULNESS.

2) But If I want to roll off high frequency (Hiss) then is this formula applicable?

NO
1) This DC blocking capacitor, along with the (UNKNOWN) input impedance forms a HIGH-PASS FILTER. It is good for rolling off LOW frequencies, but NOT high frequencies.
2) You cannot filter hiss even with a high-cut (low-pass) filter because hiss is broad-band. If you remove all the hiss frequencies, then you remove all the audio, too.

3) what is the value of Hiss in Hz

Hiss is BROAD-BAND. You cannot remove hiss with a simple filter.

in this audio: YouTube - AT897 Hiss Problem with Sony ICD-UX200

I can't hear any significant hiss in this audio. I hear a lot of ambient noise, but no hiss.

[Syed Junaid]

Originally Posted by Richard Crowley

Yes, ASSUMING that you have a 2500 ohm input impedance.
REPEATING: YOU DON'T KNOW WHAT YOUR INPUT IMPEDANCE IS, SO THIS FORMULA IS OF LIMITED USEFULNESS.

No, I'm assuming it is 3000 ohm from Manual:
"ICD-UX200: Recorder Microphone jack input for plug in power has minimum input:
level 0.9 mV, 3 kilohms or lower impedance microphone."

Originally Posted by Richard Crowley

I can't hear any significant hiss in this audio. I hear a lot of ambient noise, but no hiss.

I analyze it by iZotop RX Advance, It has two types noise one at 462Hz, other is boardband hiss >10000Hz. If use hum removal tool, set base frequency at 462Hz, filter Q at 163.72 and harmonic gain at -80dB then it tooooon is completely disappear. And the Hiss is disappear if I enable Low pass filter, Low-Pass freq. is 11437.2Hz, filter Q is 0.20 and Harmonic gain is 0.3 dB, however it slightly effect on my voice.

[Steve House]

Originally Posted by Syed Junaid

No, I'm assuming it is 3000 ohm from Manual:
"ICD-UX200: Recorder Microphone jack input for plug in power has minimum input:
level 0.9 mV, 3 kilohms or lower impedance microphone."

....

That's not the input impedance. That's the maximum impedance of the microphone that it's designed to have plugged into it. Read that specification as saying "You can use any microphone that has a 3000 ohm impedance or lower."