Newbie question: iFP-880, external mic & recording a talk

[eeN0ch]

Hi all,

My first post, and I'm totally out of my depth with this stuff. I'll need to start with some history - hopefuly not too boring.

I have a very specific task, which I've assumed would be very simple. I give a weekly talk which I publish as a podcast. Always only one speaker (i.e. me). Some time back I got onto the idea of using an mp3 player with an external mic for this purpose. I read an article which assured me that all I needed was a player with a line-in and a lapel mic.

So I picked up a T30 on ebay. Then came newbie lesson no 1: Yes you can plug a mic into the line-in socket, but the T30 (unlike some earlier iRiver models) doesn't have a built-in pre-amp, so you need one of those. This stuff no doubt is very ho-hum to most on this forum, but not to the likes of me. (Never previously heard of a pre-amp... I know zip about audio production of any kind.)

The solution to the above: forget the external mic and just use the built-in mic and do simple voice recording. So I've been doing that for about 18 months, and it's been fine. I record on "low" quality (i.e. lowest of 3 settings) and end up with a 4 or 5MB mp3 file. A quick operation in Audacity and I have a 2 or 3MB file 16khz & 16 mbps - a good size for me and my audience to work with and perfect quality for spoken word. (I of course have no idea what khz & mbps mean, but it feels good ... )

But lately ... some practical limits of the above are now getting annoying: Limit 1 - have to keep myself chained to the lectern; Limit 2 - keeping the player safely mounted on some lecterns can be rather tricky, necessitating some fiddly improvisation and near disasters. (hard floors, moderate heights ... )

So ... thought I'd find a player with built-in pre-amp so I can use the external mic as originally envisaged. Picked up an iFP-880. The mic is mono and the player has a choice of mono or stereo recording. So seemed simple enough: set line-in to mic-in & recording to mono at 16khz & 16mbps. Now for newbie lesson no 2: no sound! So much experimenting followed ... Here's what I've discovered so far:
• I get sound by setting to stereo not mono
• but the result is mono anyway (or I assume that's what it is - only comes out of left speaker)
• I get the same sound quality with any combination of the khz & mbps settings (well, as far as I can tell ... ??)
• the higher khz/mbps settings result in much larger files but no difference in sound quality
• regardless of settings, the sound quality is inferior to what I get from voice recording on the T30. In particular I get a lot of unwanted noise coming through which is almost entirely absent with the T30/voice. I wouldn't know the right vocab to describe the noise .. kind of scratchy, static (?)

So now to the question from this puzzled newbie ..... Is it possible to get better sound quality with the 880-ext mic combo than I'm getting now? Is it something to do with my recording settings? Is it something to do with the type of microphone? (e.g. Do I need unidirectional?) Or a combination of the two? Audio-geeks please help!!! (but use normal English, please ... )

(Mic specs as follows:
- Brand: Optimus (subsidiary of RadioShack/ Tandy, I think)
- Model No: 33-3013 (sold in Australia, don't know whether model nos are familiar elsewhere)
- Description: Omnidirectional Tie Clip Microphone. Broadcast quality. Omnidirectional pickup pattern. Low impedance. 70-16,000hz frequency response. Electret element. Impedance (@ 1,000hz) = 1k(Greek letter Omega). Sensitivity (@ 1,000hz) = -65dB (+/- 3dB) (0 dB=1V/microbar). Cable length = 147cm, diameter 2mm. Plug = 3.5mm diameter, mono type. )

Thanks for listening ... Answers appreciated.

[bmjelde]

No audio geek myself but I might help a bit: If the mic is mono, chances are that the input goes into the "wrong" channel on the 880; mono recording on the iFP series means recording into the left (or was it the right) channel. So if you record into the "wrong" channel - no audio. That would explain why you get audio into one channel when your settings are stereo. I've been down that road myself although with line-in recordings.

As for the noise, perhaps the mic is more sensitive to background noise than the T30 mic is. Have you tried to use the 880's internal mic for comparison? Perhaps a directive mic will suit your needs better.

You won't notice much quality difference on different bitrates when using vocal input only - the frequency spectrum you record is very limited. You will notice the difference only when playing back audio with a wide spectrum in frequency and dynamics, such as music

[earmonger]

Ah, where to begin? Your initial information was wrong. You needed a Mic-in jack, not a Line-in jack.

Recorders have two kinds of jacks: Mic-in and/or Line-in. A mic jack connects to an internal preamp that amplifies the small sigal from a mic. It may also put out a tiny bit of power to make the mic work. A line jack is made for an already amplified signal--like a connection from a stereo, a mixer, etc.--and doesn't provide plug-in power. Your T30 has line-in. Your IFP has a mic jack.

OK, your current situation:

You are plugging a mono mic into a stereo jack. Compare your mic plug (mono, one ring around the plug) with your headphone plug (stereo, two rings). So you are only getting sound on one channel. The mono setting on the IFP may be looking for the sound on the other channel, where there's no connection.

I don't think you're talking about background noise in the room. If that's what the mic was picking up, then a directional (also called cardioid) mic might help. But since you mention static, I think you're talking about electronic noise.

The noise could have two causes. One is a loose connection: to the mic, to the jack. You'd need to get another IFP if that's the problem.

But it's probably not. Your mic is a low-sensitivity mic, generating a signal that your preamp is struggling to amplify. Every preamp adds noise; the teentsy one in your IFP is obviously not a fancy low-noise outboard preamp. The preamp may also be sensing one channel of silence and going crazy trying to amplify a signal from it.

Possible easy solution: Get a mono-to-stereo adapter for your mic at any electronics store. Ideally, get a short cord with mono jack connected to a stereo plug. The reason for that (rather than the stumpy little adapters you can also find) is because a little plug will put less mechanical pressure on the jack than the leverage of the stumpy adapter. So your mic jack won't wear out as fast.

Also, get the mic as close to your mouth as you can. Experiment with placement--you will be amazed at the difference by putting it to the side, under your chin, directly in front of your mouth.

More elaborate solution: Get a higher-sensitivity one-point stereo mic (which is two microphones, left and right, in one unit), or even a mono mic and run it through a mono-to-stereo adapter. Get a directional one if you want.

You can look at specifications for sensitivity. It's in negative numbers, so -30 is higher sensitivity than your -65. Two places to look for mics are http://www.soundprofessionals.com and http://www.microphonemadness.com. They have a 30-day guarantee in case it doesn't work for you.

Incidentally: Kbps--kilobits per second. How many chunks of data (bits) are being used to encode every second of sound. The more chunks, the bigger the file. Use the lowest rate that sounds good to you.

[eeN0ch]

Hi guys,

Just wanting to say thanks very sincerely for these exhaustively thought-out responses. I thought I was subscribed to my thread here, but never received any notifications. And having been rather flat out lately, I had totally forgotten about having even posted here.

Having just now discovered your comments, I at least want you to know that I'm grateful, and that you haven't written all that stuff so patiently for no appreciation. Hopefully I'll get back to this particular project in due course, in which case I'll certainly try some of your tips, and post back.