Separate L/R Levels in Stereo file possible with handheld recorders?

[Greg Miller]

Originally Posted by Jim Andrada

I was just wondering if it would work to use the Y cable and put a 10 or 20dB pad one branch of the Y so you didn't have to fool with independent levels in the menu. Just a thought.

Yes, Jim, that's a good idea, and that would work just fine! Such a pad could be made using just three 1/4 watt resistors... total cost under $1.00 (plus cost of connectors, of course).

If we want to make the pad accurately 10 or 20 dB, we need to know the source impedance of the mic and the input impedance of the recorder. Tell me the specs of the equipment in question, and I can easily calculate the resistor values.

[Marcus Rieger]

Wow thanks for the detailed answer. I swear i read it twice from beginning to end, but even so i am just starting to get the principle of it. I don´t know enough about electricity and sound to follow along.

right now i am not sure what microphones and recorders my audio kit will consist of. Probably a Rode NTG2 or NTG3.

I am also thinking of a different setup, because i listened to some samples of the zoom H4n and it has quite some noise in my opinion, as has the Tascam Dr-100. The Marantz PMD 661 is better in my opinion, but but has no limiters...

So another way could be to buy a Sound Devices MixPre with great preamps and limiters and feed that into a Edirol R-09. I am thinking about the Edirol R-09 just because thats what they use in an B&H Promo video. Although they use it together with a Sound Devices 302. I don´t know if it works better together with the Sound Devices mixers than the other recorders or not.

Klick on the "Item Demo" button to see the video at B&H:
(http://www.bhphotovideo.com/c/product/559244-REG/Edirol_Roland_R_09HR_R_09HR_Portable_High_Resolution_Audio.html)

It seems the Problem with the other recorders is, that you don´t want to just connect the XLR outputs of the Mixer to the XLR inputs of the Zoom H4n for example because then you still use the noisy preamps of the zoom. You have to use line in. Then the problem is that the signal is too hot. Maybe the Edirol recorder can compensate for that? Or maybe i can just use a real cheap recorder when using line in?

Lots of things to think about :)

Again thanks for the answers, much appreciated!

[Greg Miller]

The calculations are based on the fact that any signal source like a microphone produces a voltage, and also has some internal resistance. (In the case of a dynamic mic, this is easy to imagine, the internal resistance is the resistance of the thin wire in the winding of the mic coil.)

And any typical load, like the input of a recorder, has some measurarable resistance.

When you connect a signal source to a load, the voltage generated by the signal source is actually divided between the source's internal resistance and the resistance of the load.

My explanation would be a lot easier to follow if I were at a whiteboard and had a laser pointer. ;) Meanwhile, you might want to search for "Thevenin generator" or something similar. (Of course like all info found in the internet, some might be right, some might be wrong, some might be clear, and some might be badly explained. YMMV... Your Mileage May Vary as they say in the automobile adverts.)

I could have sketched some schematics, and included some more math, but that would have been rather time consuming for me. Frankly, I didn't know if any reader would be interested in that level of detail.

If you (or another reader) really wants a more thorough (and hopefully more clear) explanation, please reply and let me know, and I'll find time to put one together in the near future.

--

Meanwhile, as to your specific question about line inputs: Line inputs are usually much better able to handle high input levels than are mic inputs.

You would not connect a mixer's XLR outputs to a recorders MIC inputs... you would connect to the recorder's LINE input. That shoud completely eliminate the use of the mic preamps in the recorder.

A mic input is frequently wired directly into a preamp IC, and an IC can be overloaded if the incoming signal level is too high.

In olden days with valve equipment, the line input was frequently connected directly to the "Line level" potentiometer... the rotary control that set the recording gain for line input. Being a passive device (no amplification), a potentiometer won't generate distortion like an IC will; it will work at any level, until the level becomes so high that it actually burns out the potentiometer. (You will notice a "burning electrical smell" when this happens!)

Our new recorders frequently don't even have rotary potentiometers, but rather some sort of solid state digital gain control IC. Therefore, today's Line Inputs are not quite as immune to overload as olden ones. Even so, they are designed to take pretty high levels.

Worst case, if a given mixer has much too much output for the line input on a given recorder, again, you just build a fixed attenuator "pad," in this case using two or three resistors (per channel) and that reduces the level to one that keeps the recorder happy. So, again, it's first a question of knowing the specific mixer and recorder in question, then looking up the specs, and finally calculating the resistor values (if any are needed).

[Joel Guy]

To get back to the original question (sort of) - specifically concerning the Marantz pmd 661...

Is it possible to monitor and control both xlr mic inputs separately?

From everything I've read, it seems like you have to apply the controls to both mic input's together. For example, after looking through the owner's manual online, it seems that if you turn up the gain, it has to be for the mic/line inputs together, without control over each mic separately.

I also wonder about the recording volume... can this be adjusted on a single mic basis?

[Rick Reineke]

Yes,
Why don't you download the users manual.

[Joel Guy]

Hi Rick,

I did. But I didn't see anything that indicated I could, for instance, set different record levels for xlr input 1 and input 2.

Can you reference a page in the manual?

[Greg Fiske]

As far as I know this has been corrected in the latest firmware, so I don't know if that change has been corrected in the manual. On the H4N I would install the latest firmware and test it out.

[Rick Reineke]

Marantz PMD 661 manual. Page 9,

Item 3. REC LEVEL Control
"Turn to adjust the record level when the “Level Cont.” of preset
menu is “Manual”.
The inside control (Right channel) and outside control (Left
channel) turn together, unless you hold one while turning the
other.
The optimum record level is when the level meter goes as close
to 0dB as possible but does not go OVER."

[Joel Guy]

Thanks, Rick!

[Renton Maclachlan]

Originally Posted by Greg Fiske

As far as I know this has been corrected in the latest firmware, so I don't know if that change has been corrected in the manual. On the H4N I would install the latest firmware and test it out.

I've just downloaded the latest firmware and the xlr input volumes can be separately adjusted in the H4n...

[Charles Hurley]

The D.Mono mode on the Marantz records input 1 to both the left and right channels with the right attenuated 20db, it also offers full manual control of both channels.