problems with iMic recordings

[DanA]

Hello,

I recently bought the Griffin iMic, but it doesn't seem to be getting on with Audacity. When I try recording there is hardly any sound at all - it sounds very distant and weak even at the highest setting. When I connect the mike directly to the inline socket on my PC I get a much stronger signal, but with rather poor sound quality (which is why I wanted to upgrade to better equipment in the first place).

I selected iMic as the recording device both in the Audacity Preferences and in the Windows Shortcut to Sounds and Audio Devices settings, but this didn't help.

I also tried updating from Audacity 1.2.4 to Audacity 1.3.3-beta (Unicode), but this made no difference.

Any ideas what may be the reason? I first thought I may need an amplifier, but from other comments I assume that iMic should be sufficient, and I'm a bit reluctant to spend even more money without being sure about the exact cause of the problem.

Here's some more info that may help:
-Dell Dimension 2400
-Windows XP Home Edition, version 2002, SP2
-Pre-installed soundcard (used for playback): SoundMAX Integrated Digital Audio
-Griffin iMic
-2 Stereo/Mono Condenser Microphones (with fresh batteries) (also tried using just one mike, but made no difference)

I'd be delighted if anyone could help! Please let me know if you need any more info.

Many thanks and best regards

Daniel

[kozikowski]

<<<-2 Stereo/Mono Condenser Microphones>>>

Which are....?

Made by....?

Koz

[alatham]

We also need to know which plug you're using to plug those mics into.

If they're professional mics, then you won't be able to plug them directly into either of those inputs. You'll need a mic pre-amp to boost the signal to Line Level and plug the pre-amp into the Line In.

[kozikowski]

I will tell you that the early version of the iMic claimed to have a microphone level input and sorta worked, but the recorded show was just so noisy that over half of the users gave up and put it in the garage.

You may be solving your own problem, however. If you have reasonable quality microphones and both the sound card and the iMic fail, then the layer between the microphones and the computer may be no good. Microphone connections are a little magic because they put battery voltage on one of the wires and you have to know it's there.

Koz

[DanA]

Dear Koz & alatham,

Many thanks for your answers.

1) Type/Make of Microphone:
I don't think it's a professional mike, as it was just £20 ($30) each.
Here are the specs:
Make: Yoga Stereo/Mono Condenser Microphone
http://www.maplin.co.uk/module.aspx?ITA ... =4m10#spec
http://www.yoga.com.tw/ Model EM-278
Directivity: Uni-Directional
Frequency Response: 100Hz - 16kHz
Impedance: 600Ω
Sensitivity: -48dB
Features: Stereo/Mono/Off switch
3.5mm R/A stereo jack.

2) plugs:
I plug the mike directly into the iMic (using the 3.5mm R/A stereo jack on the mike). The iMic plugs into the computer via an USB port. When I use two mikes I've got a Y adapater; don't know the exact specs of it, but the problem also occurs with one mike only. As I said, I don't think it's a professional mike, so I'm not sure if I really need a pre-amp. This equipment was recommended in another thread (http://www.soundonsound.com/forum/showf ... o=&fpart=1) and they didn't say anything about amps.

3) 'the layer between the microphones and the computer may be no good'
Sorry, you've lost me there. What kind of layer would that be, and how can I fix it?

Thanks a lot for your help!

Best regards

Daniel

[alatham]

Wow, I can't find any really useful info on that mic.

It seems to be the kind of mic you would plug into a camcorder or something like that, but I can't really get any concrete info from the manufacturer.

I could go on a rant here about the state of the non-professional microphone world, but I'll just say that it can be very confusing figuring out how to connect everything together.

It's much easier (albeit more expensive) in the world of professional microphones since the expected signal levels haven't changed in at least 40 years. Unfortunately that's the case in the non-pro world.

But back to the topic at hand. I think that mic isn't designed to be plugged into either the Mic In or the Line In on your iMic. I think it was designed to be plugged into a camcorder or a tape deck with a "mic" input. The confusion stems from the fact that the two inputs are labeled the same, but the "Mic In" on a computer expects a different signal (and/or pin configuration) than the "Mic In" on a camcorder.

From what I can tell the iMic has two different inputs (at least the current model does), which one are you plugging into? I would think you would get at least some signal from the Mic In, but I'm not sure how good it would be (this seems to be happening). Also, you do have a battery installed in the Microphone, right (it requires 1 AA)?

I'm not certain, but you might be able to use a pre-amp to get a good signal from that Mic. But I don't want to recommend anything until I know what you're trying to do with it. Can you tell us that? If so, please also let us know if it's possible to return your microphone and your iMic, I might recommend buying something else entirely.

[DanA]

Hi alatham,

Many thanks for your detailed answer – much appreciated!

From what I can tell the iMic has two different inputs (at least the current model does), which one are you plugging into?
>>> I plug the microphone into the 'In' input of the iMic.

I would think you would get at least some signal from the Mic In, but I'm not sure how good it would be (this seems to be happening).
>>> That's correct - it's very weak, but it's there. It doesn't get much louder however much I turn it up in Audacity or Windows, but it gets distorted very soon.

Also, you do have a battery installed in the Microphone, right (it requires 1 AA)?
>>> Yes (I double-checked)

I'm not certain, but you might be able to use a pre-amp to get a good signal from that Mic. But I don't want to recommend anything until I know what you're trying to do with it. Can you tell us that?
>>> I'm trying to record piano and voice. Incidentally, I managed recording piano by connecting the mike directly to the input socket on my PC (which was the method I used before with a different mike). It works but the high notes are quite distorted. Just about tolerable for piano, but with voice it gets pretty horrible, that's why I was looking for better equipment.
>>> I once tried connecting a MiniDisc and using it as a pre-amp. It did boost the signal, but I couldn't work out how to control the volume; it just kept being too strong. If I try fiddling around with this (connecting Mikes to MiniDisc, then connecting MiniDisc to iMic and using the Line inpt) do you think I might get lucky?

If so, please also let us know if it's possible to return your microphone and your iMic, I might recommend buying something else entirely.
>>> I don't think so, since the equipment is working - it just does not seem to be the right kind of equipment. Like I said, someone else recommended exactly this stuff and said 'This is a very simple, inexpensive and unscary setup for non-experts which I've recommended to many people, all of whom have been delighted - I've known it used for recording everything from a symphony orchestra to a solo mandolin.' So I'm still hopeful it may just be due to wrong configuration. BTW, I also posted to the thread where it was recommended but sadly didn't get any useful reply from there.

Many thanks

Daniel

[alatham]

I may have been in error about the iMic. It does look like it's only got 1 input. Does it have a switch to toggle between Mic and Line level? You should probably have the iMic set to Mic level.

But even then, then iMic website has something interesting to say:

I’ve plugged in my $150 mic and it doesn’t work. (Mac and PC)

Not necessarily. The iMic was configured for Mic and Line Level devices, such as standard computer microphones and tape decks. Those devices (and there are many types) typically are high impedance products that connect via unbalanced cables. Many, if not most, professional or higher end microphones are low impedance products that connect via balanced cables. Those types of devices require preamplification to bring them up to Line Level. This can be accomplished by using the pre-amps of mixing consoles or by using an impedance matching transformer. If you don’t have a mixer, the transformers are readily available at electronic supply houses and consumer outlets such as Radio Shack.

Your 600 Ohm mic qualifies as somewhere between Low-Impedance (generally less than 300 Ohms) and High-Impedance (generally higher than 1.5K Ohms). I'm not quite sure what this means with regards to plugging it directly into the iMic input. There's a good chance that the Low -> High impedance transformer that Griffin mentioned will help. But, as an electrical engineer, I have to say that this method is a kludge and you would do better with a proper pre-amp. Personally I use the Art Tube MP, it's about $40 and it sounds nice and warm to my ears (but your mic will do more to color the sound than this pre-amp will, so your mileage will vary).

Your comment about using a MiniDisc player as a pre-amp sounds reasonable. But I don't know enough to say for sure.

I don't know why this mic seems to be distorting, and with some tweaking of the setup you might get the distortion to go away. But you're still left with a mic with a very low amount of sensitivity. The problem is that you will always be limited to signals that are within a small range of volumes, but real world signals like that are difficult to find / perform.

Which website recommended this setup? I'm sure there are $60 - $80 USB mics out there that have much nicer specs and don't require any other equipment.

[DanA]

Hi alatham,

I may have been in error about the iMic. It does look like it's only got 1 input. Does it have a switch to toggle between Mic and Line level? You should probably have the iMic set to Mic level.
>>> Yes, that's what I've got: iMic switch set to Mic level.

Which website recommended this setup? I'm sure there are $60 - $80 USB mics out there that have much nicer specs and don't require any other equipment.
>>> http://www.soundonsound.com/forum/showf ... o=&fpart=1

Many thanks for your help! I think I'll start looking around for a pre-amp...

Best regards

Daniel

[kozikowski]

<<<I think I'll start looking around for a pre-amp...>>>

I think I won't wait up for you. I'm designing my own mic preamp because nobody makes what you really want--a little box that you plug your mic into and then on into the interface or computer. If you search for "MicPre," you're going to find all the terribly upscale microphone processing amplifiers with the glowing meters, pulsing lights and $2000 pricetag. There is no downscale. My tiny FP-24 microphone preamplifier and mixer...

http://www.shure.com/ProAudio/Products/ ... 24_content

...was almost $1000.

Under that, you're supposed to plug your mic into a Sound Card with a microphone connection (usually pink) or buy a USB microphone which has a MicPre built in. You need to know that the latest sound cards short-change the microphone connection and it doesn't work very well.

If you find something smaller/cheaper, I'll stop designing, but I'll keep going while you look.

Koz