M-Audio Fastrack Pro USB w/ AT822- low mic level.

[Jonathan Levin]

Hello again.

I'd like to reach out to those who have experience with the M-Audio Fastrack Pro USB series interface.

I am having a difficult time getting a decent audio level for some simple voice over and I'm I have no doubt it is something that I am doing wrong.

So here is my set-up first:

First, and this may be the problem here right away, I'm using an AT822 mike (until I get lav and shot gun) connected to the M-Audio FT.

(If anyone has followed my thread http://www.dvinfo.net/forum/all-thin...sound-pro.html starting around post 17, where I got two types of connectors)

Gain on the FT Pro needs to be turned up all the way to get a semi decent level. This in either Garageband or Soundtrack Pro, both current versions running on Mac Pro 10.8.2

I've have tried all combinations of connecting the mic to the interface: with and with out adapters, and so on.

All connections are with the xor/neutric plugs on the front of the FT Pro.

Any advice, and please ask any questions that may help with this.

Ultimately, my goal is to record to HDD on a MacBook Pro in the field voice over, export a AIFF file to place in NLE. I thought this might be a good solution.

Thanks.

Jonathan

[Jay Massengill]

I have an M-Audio Fast Track Pro that I bought on a super-duper sale... I haven't opened the box yet, because the reason I bought it keeps getting postponed. Also I'm on PC, not Mac.
However, there are a couple of points I can mention.
First are you certain the mic has a fresh alkaline battery and the battery contacts on the mic and the battery are clean and free of corrosion or fingerprint oils?
Second you must use your "XLR unbalanced stereo to two unbalanced mono XLR" adapter (and the adapter must be wired correctly) to have any chance of this working with this interface. The 1/4-inch jacks on the interface are for Line or Instrument level signals. The XLR part of the combo jacks is for Mic level signals.
Also make sure the pad is not engaged on the interface.
The AT822 has a moderate output, more than a dynamic mic but much lower than most condenser mics. It may be too low a level for your situation.

[Jonathan Levin]

Thanks Jay.

Yeah new battery. All buttons confirmed in proper settings.

I did get better results using the cable that came with the AT 822 Stereo mic. XLR at mic end to two tip sleeve phono connectors at the other end. I plugged each of those into the FT Pro's inputs. So it looks like it's going from a balanced signal to un-balanced input(?)

In Garageband, I first selected stereo for the input, but since if I ever have to use this particular mic in an emergency I found that setting the input to mono sounded a little better.

However in mono, one side of the mic seemed a little "hotter" than the other.

Either way, once I get my sound package together, I won't be using this for interviews as was covered in the stereo mic thread.

Jonathan

[Les Wilson]

As Jay says, you need to know the impedance (line/mic) of the audio interface that you are plugging into. You mic must plug into a mic level input. These interfaces often auto switch to line level when you use the 1/4 inch inputs as it sounds like you are doing

[Jonathan Levin]

Hi Les.

The inputs have switchable line/mic button. I have them set to mic level.

Jonathan

[Jay Massengill]

No the SWITCH is Line/Instrument and only applies to the quarter-inch part of the combo connector when using an unbalanced connector.

The CONNECTOR is labeled Mic/Line but you have to use the XLR part of the combo connector to actually get a Mic Level input, which is much more sensitive than Instrument or Line level inputs. The manual says you can also use the quarter-inch for mic level but it MUST be a balanced TRS connector.

[Jonathan Levin]

DOH!

Jay You're right! Sorry I mis-read the button on the FT Pro. It is indeed a switch from mic to instrument. As are the inputs labeled inst/mic.

So are you saying that if I use the mic with a xlr connection I set the switch to mic? Instrument would be for 1/4" phono like a guitar cable?

When I had the mic plugged in (XLR) and the button set to mic, that's when my levels were really weak unless I turned the gain completely up.

Interesting that the mic seems to get better levels with the phono plugs than the XLR

I used to have the instructions for this thing or I probably wouldn't be asking a bunch of dumb questions.

[Jay Massengill]

I think I know what's happening. I just remembered that the combo input connector's terminals are simply in parallel and so what's happening is the unbalanced XLR connectors of your adapter cable are making the input default to Line/Instrument just like you were plugging in an unbalanced TS connector.
You'll need to either get a balanced mic, or use a balancing transformer to convert your unbalanced output quarter-inch adapter cables to an actual BALANCED XLR or TRS connector.

Manual at:
http://www.ee.bgu.ac.il/~acl/Equip/F...ckPro_hero.pdf

[Greg Miller]

Jay:

I don't have a Fastrack, but I'm looking at the online manual right now.

I wonder whether the TRS and XLR inputs are really in parallel. In at least two places, the manual says that the "Inst/Line" button does NOT affect the XLR input, only the TRS input. Also, the manual says mic input impedance is 2.7k ohms unbalanced or 5.4k ohms balanced, but the instrument input impedance is 220k ohms unbalanced only. All of the above leads me to believe that the two sets of contacts are not connected in parallel, but rather go to different places in the circuitry.

---

Jonathan:

Be absolutely sure that the 48 volt phantom power is turned OFF! If you are sending 48 volts back out to the mic (on the mic's signal wire) you might compromise the level, or -- worst case -- you might even damage the mic!

Then be sure the "Line/Inst" switch is in the "Inst" position (button out). Also be sure the "Pad" is out of the circuit (button out).

And by the way, TS and TRS connectors are called "phone" and NOT "phono."

A "phono" connector is more correctly known as an "RCA" connector, and looks like the attachments. They were often used for connections to the pickup cartridge on analog phonographs, which explains the origin of the inaccurate term "phono" connector.

Phone connectors come in two common diameters: 1/4" (sometimes approximated to 6.5mm), and 3.5 mm (sometimes incorrectly referred to as 1/8"). Actually, there was an exact 1/8" connector about 40 years ago, but as most manufacturing was migrating to metric-friendly countries, the size actually did change to 3.5mm. If you ever come across a true 1/8" plug, it will fit very loosely in a newer 3.5mm jack, and may not make reliable contact.

[Jay Massengill]

It's hard to know for sure from afar, or until I actually open and use my Fast Track Pro, but Page 3 of the manual says you can input a mic level signal into either the XLR or TRS connector using balanced plugs, while line/instrument signals are input using TS unbalanced connectors to the same quarter-inch jack. Since there isn't a "mic" level switch, and you can input mic level signals into the quarter-inch connector (the same connector used for TS line/instrument level signal) I think the connector must auto-sense whether a balanced or unbalanced connector is attached. Or it's simply the fact that the gain for Instrument and Mic connections is very similar (page 10 and page 14).
M-Audio may be assuming that any XLR connector will be balanced, but in this case using a stereo unbalanced mic with adapter cables, the XLR output from this mic is unbalanced.
And as you stated, if the phantom power is on that would be very bad and could not only damage the mic but also the Fast Track, as well as giving unpredictable results with the input levels.

[Greg Miller]

Yes, Jay, the manual has very confusing language.

I see what you say about balanced mic input on XLR or TRS. Then on p.5 it says, "Connect... an instrument (using TRS/TS connector only)..."

Now note the specs on p.14, which say the mic input is 2.7k ohms unbalanced (or 5.4k ohms balanced); and also that the instrument input is >220k ohms unbalanced.

So they seem to be contradicting themselves. P.3 says TRS is a balanced mic input (2.7k ohms unbalanced), yet p.5 says TRS is an instrument input (>220k ohms unbalanced). Well, it can't be both!

This is why I lament the lack of schematics in a lot of today's equipment. Back when audio guys were engineers (as opposed to today's "appliance operators,") every manual for every reputable piece of gear included a schematic. If the verbal description wasn't clear (or if you just didn't feel like reading through pages of sales literature) you just looked at the schematic to see what was happening inside the box. Now it's a mystery.

If I had a Fastrack here, I'd open it up (assuming I could even find the screws) and trace the wiring, to at least see whether the jacks were wired together or not. Well, it's in your court now...

[Jay Massengill]

I guess I'll have to try out my AT825 balanced stereo mic, which has lower output than the AT822. If it works reasonably well with the Fast Track Pro then it may point to the unbalanced nature of the OP's mic or adapter cables as a problem with the interface inputs.

[Richard Crowley]

Can we assume that you are:
1) Speaking in a normal voice. Not whispering, etc.
2) Placing the mic at a reasonable distance (6-12 inches)
3) Speaking into the mic on axis to ONE of the two mic capsules
(i.e. 45 degrees "OFF AXIS" from the body of the microphone.
You CAN NOT use this microphone "on-axis" and expect reasonable performance.
4) Using ONLY ONE of the two microphones inside the body.
That means DISCONNECTING one of the two outputs from the mic
5) Testing ALL the available mic inputs.
6) Aware of which output is which (Left and Right)

[Jonathan Levin]

Richard and Jay. Thanks for your advice.

Richard, yes I absolutely make sure the 48v phantom power switch is off for the mic, otherwise I'll be eating BBQ AT for dinner. And yes I meant Phone not "Phono", as those are the RCA type connectors.

And yes on the ideal off-axis for this stereo mic.

Why is nothing simple?

Thanks fellas.

Jonathan

[Gary Nattrass]

Originally Posted by Jonathan Levin

Richard and Jay. Thanks for your advice.

Richard, yes I absolutely make sure the 48v phantom power switch is off for the mic, otherwise I'll be eating BBQ AT for dinner. And yes I meant Phone not "Phono", as those are the RCA type connectors.

And yes on the ideal off-axis for this stereo mic.

Why is nothing simple?

Thanks fellas.

Jonathan

Actually and please don't take offence as this is a general statement rather than directed at you Jonathan the principles of sound and making movies have been simply defined for many decades.

Yes new technology and kit comes along but the basic principles have not changed much for decades, the problem is that people and manufacturers try to re- invent wheels and it ends up that wrong applications become the norm and it ends up causing confusion and people trying to cut corners.

The other aspect is that people tend not to understand the basic physics of light and sound so it also ends up with kit being pushed beyond the laws of physics and these forums then being filled with the why is my sound not like a 5.1 blockbuster with my lav or rode videomic, or why is everything out of sync when I try to do sep filmic sound on my own with my $100 recorder?

The same goes for the pictures and we get the new searching for focus on my own with no focus puller genre and the why does my 96 led camlight not give me that beautiful imagery that I see in the cinema or why won' t my camera shoot in zero light!

Hey ho and lets hope some help can be given but I do question some of the initial purchases people make and then the quest to try and make it all work only to end up having to bodge things together to get any decent results!

Rant over and sorry but is can be ever so easy with less kit chasing and more fundamental understanding of the real simple basics!