I also have a C840 and am having trouble getting a table microphone to work properly.  A headset plugged in works fine, but the table mic will not work unless it is close to you mouth, which of course defeats the purpose.  The mic manufacturer says to find out if the laptop has microphone level imput or just line level input.  The table mic requires microphone level input.  I can't seem to find out which type of input this laptop has.  Anyone know how to find out?

This is partially the same problem I have. The C840 is supposed to have Cirrus Logic's Crystal Fusion soundcard, which is one of the best non-pro cards made. Unfortunately, there is no information about how Dell employs it in the C840. It has both a line-level and mic-level input, but--like you--my mic input definitely does not have enough gain to deal with a standard Shure pro quality dynamic microphone that works perfectly in every other piece of audio equipment I have that has mic level inputs.

According to the specs at the Cirrus Logic site, this trouble should definitely not be the case for this soundcard. I have already ordered an Echo Audio PCMCIA pro quality soundcard, because I cannot get useful information from Dell to solve the problem.

Pity. FYI the CD burner on my C840 also quit burning just a few months out of warranty. These problems just about do it for me with Dell.

The C840 only support video output on the S-video connector,  but I can tell you that using something like the Pinnacle MovieBox DV therough the firewire port on the C840 is an excellent input source for video capture.  That device supports audio & video input (RCA, S-Video & Firewire for video in,  and RCA stereo & Firewire for audio in).  It supports output on any of the same set of ports.  This device allows [almost] any analog or digital source to be captured to your PC via the firewire port. 

Pinnacle also sells a version of this device which connects to the PC via USB 2.0,  but I have never used it so I can't speak to it's quality or performance.

I am not familiar with any PCMCIA card that is truly flush to the unit. All of them extend out a bit (if for nothing but just to grab it), as does the Echo Audio card. With the Echo card, the bit that extends is where the connection for plugs and a volume control are located.

If you are using video, then I agree with the comment about exploring Firewire. You may be able to plug the audio into your camera and have both audio and video delivered to the computer for recording that way. The S-connector should also be explored if your camera does not support Firewire. Almost all video cameras (except pro models) support the S-connector.

When I was still using my C840 heavily,  I used Firewire to connect my digital camcorder to the PC.  Later,  I used a Belkin USB 2.0 PCI card in a C-Dock II station with the same system.  Both solutions worked very well for me.

I don't have any experience with PC-CARD sound cards,  but I thought I saw one from Creative Labs which used a "pig-tail"/"dongle" so the card itself would have been flush to the side of the notebook.

You get what you pay for.
If you buy a real Mic and Mic amp it works fine.  Theres no standard for PC mics.  if there was laptops would have a standard 600 ohm XLR connector for mic input.

Shure has a page dedicated to how to hook a mic to a pc.

http://www.shure.com/support/technotes/app-soundcard.html

http://www.m-audio.com/products/en_us/FastTrackUSB-main.html
http://www.m-audio.com/products/en_us/Luna-focus.html

 

Pc sound cards are not going to have a high impedance input. Most need either a preamp or some other input buffer. The Maudio box is usb powered and matches up XLR 600 ohm mics.

Signal Level
Professional microphones put out a very weak signal - less than 1/1000th of a volt, or 1 millivolt. Audio inputs on sound cards, even though they may be labeled "Mic In" or be identified by a small microphone-shaped icon, often are not designed to accept such a low signal level. Most sound card inputs require a minimum signal level of at least 1/100th of a volt (10 millivolts); some older 8-bit cards need 1/10th of a volt (100 millivolts). This discrepancy means that if a typical professional microphone is connected to a sound card input, the user will have to shout into the microphone or hold it just an inch or so away (or both) in order to produce a strong enough signal for the sound card to "hear."

There are two possible solutions. One option is to increase the sensitivity of the sound card input, so that it can more easily detect the signal from the microphone. The software supplied with some sound cards allows the user to increase the sensitivity or "gain" of the input, either with a click-and-drag input level control or a set of check boxes that double, triple, or quadruple the sensitivity. (Note: Increasing the sensitivity of the input will always add some noise, so use only as much additional gain as necessary.)

If the input sensitivity cannot be increased, another option is to amplify the microphone signal before it goes into the sound card input. This can be done by running the microphone signal through a device called a mic preamplifier or mic-to-line amplifier. A microphone mixer can also be used if it has an output that will provide adequate signal level to the sound card input. (In this case, the mixer is being used only for its preamplification function and not its mixing capability.) Either way, you will have to know the typical output level of the microphone (found on the microphone’s specification sheet) and the sensitivity of the sound card input in order to know how much amplification is needed, and whether a particular mic preamp or mixer will do the job.

Message Edited by SpeedStep on 01-18-2006 04:57 PM

I paid a LOT for the C840!

And as yet, my original questions are still unanswered.

Message Edited by Jake114 on 01-18-2006 03:16 PM

My table mic has an impedence of 1000 ohms.  I'm not using a sound card.  I'm using the C840 mic input jack and have no idea what the impedence is for that.  Is there any way of finding out that impedence?