Using a standard Stratocaster-type guitar, with standard pickup wiring, when plugged into a normal amplifier (Peavy, Roland, Berringer Mixer, etc), the volume control works much as expected. Its clean and smooth and the volume change is somewhat spread across most of the travel.
When coupled into a PC soundcard input, the situation is different! The volume and tone controls have to be set at maximum, and sound scratchy noisy when adjusted. There is a "sweet spot" near maximum, where going any further to flat out makes the signal quit altogether. I cannot figure why.
I used an adapted cable into the mic input (red), because it is a high impedance input that will not significantly load the pickups, and has a 20dB boost and software mixer gain controls. I did link the Left and Right channels together (and make real SURE that I never inadvertently offer the parallel linked jack at an output!)
I had thought the input impedance of the PC mic input might be just too high, so I tried 100K across it to make it look more like a amplifier. The trick did not work.
Have I got this all the wrong way around? Is a PC mic input actually a low impedance thing?
Direct from guitar to pc is unlikely to work well. You are much better going into the line input of a standard sound card, but via another device. This can be a mixer, a modeller pedal, or even a stompbox acting as a buffer. In order of quality of sound, the best results is either from a mic on a guitar amp and into a mixer, or from a modeller pedal, designed to emulate the response of amp and cab. Or if you use a simple pedal as a buffer (eg a non-true-bypass pedal switched off), you can get a clear clean tone, which you can adjust with software later.
I've never heard of a standard PC mic input that was stereo.
Don't think they're balanced either. If it were, you shouldn't get anything out of it at all the way you've described your cable since your feeding the same signal to both the inverting and non-inverting inputs. 1-1=0
If there's a TRS jack there, the R part is probably for DC voltage to power the mic element. DC voltage across your pots could cause the scratching you describe. The tip connection should go through a capacitor on its way to the first active stage. If it's not, or the cap is leaky, you could be throwing off the bias for that active stage, which might cause clipping or gating or other strange phenomena.
Use a buffer and run into the line input.
Last Edit: Jun 17, 2010 1:05:45 GMT -5 by ashcatlt
I agree - as I've used the line in method suggested by ash.
In fact, I've done so by simply running a standard guitar patch cord directly from the amp (line out or headphone jack, depending on which amp I am using) to the PC line input.
You probably know this, but the line in is typically found on the back of the computer - it's not the mic input typically found on the front.
Here is a link to two recordings done exactly as described above : "Push Pull test" ; and "Woman Tone" - note: you will notice that Woman Tone sounds muddy ; this was done on purpose, as the tone control was set to zero.
I'm not saying they sound particularly wonderful, but the method used was ultra-simple and the recordings still do not have any of the noise you have described.
I just got to say it... when it comes to the mic input on the computer... Just Say NO... it just is not viable for any recording purpose... unless you are using software that has compensated for its shortcomings, like Amplitube... either use the line in with a mixer, like Alesis makes, or better yet, go with a USB recording interface, either will work a hundred times better!
You've posted several times and no one has properly welcomed you, so . . .
Hello and Welcome to G-Nutz2!
You are right about the mic input. The whole "direct-into-soundcard" idea we used to call "guerilla recording"- simple and cheap to do, with adequate results.
But nowadays, there is really no good reason not to use a USB interface. Cheap ones are now down in the $25-$30 range for just a basic unit, but so much better than direct in!
I use a Lexicon Alpha, cost me about $70- has 4 inputs (2 mic ins, 2 instrument), separate rec vol and headphone vol controls, and it came bundled with Steinberg Qbase software and Lexicon's reverb .vst stuff. Can't beat it with a stick!
But I see cheap single-input ones for cheap on MF all the time, no cost excuse anymore not to have one of these.