Audacity Forum

Hi All,

First of all I want to say how incredibly awesome audacity is... I was able to RECORD my first song after I found this free software
check out the song at http://www.youtube.com/watch?v=AFGRUkwIv68 and let me know what you think...

My reason for posting is I'm unsure if my mic (piezoelectric pickup) is recording improperly, and regardless, whether or not audacity has a tool to manipulate the recorded audio.
I have posted the image screen shot here http://s4.tinypic.com/24q5vmc.jpg for you guys to see exactly what the problem is. At the bottom (the audio i have highlighted), the peak amplitudes seem to be consistently shifted down... I am recording directy through soundcard, using the Line-In function, plugged in directly to my Breedlove AD25/SR Plus Guitar through the Fischmann Classic 4T (piezoelectric)Pickup. The sound recorded is quite a bit different than what is heard by my ear. Is it the pickup itself creating this problem? Causes? Are there any ways to fix it? Please let me know what you guys think, Im thinking about not recording through the pickup and just using the MXL .008 USB mic I have to record the audio and avoid this problem.

Thanks!!!

Please don't triple post the same query - it only annoys the volunteer folks who work this board - and it never gets your question answered any quicker. I have deleted the duplicate postings to avaid any parallel threads developing.

Sorry I can't answer your question - but there are are couple of other forum pixies who do know about this stuff and usually call by the whole forum most days - one of them will be asleep right now, but will wake up in Pacific Coast time ....

and hey, I like the song on YouTube that you posted the link to.

WC

allrightythan8 wrote:At the bottom (the audio i have highlighted), the peak amplitudes seem to be consistently shifted down...

It is not at all uncommon for audio to not be symmetrical - it frequently happens when using high pass filters (which will part of the circuitry in your pre-amp).

allrightythan8 wrote:The sound recorded is quite a bit different than what is heard by my ear.

You mean that the recorded sound is different to the acoustic sound of the guitar?
Again that is not uncommon. Pick up manufacturers try hard to make the sound from a pick up as much like the acoustic sound as they can, but the perfect pick-up has not yet been invented. When you listen to the sound of a guitar acoustically, you hear the sound from the entire guitar as it resonates. A piezo pick-up is localised to the bridge, so it is never going to sound exactly the same.

For a natural guitar sound, you should be able to get better results using a microphone. Don't put the microphone too close to the sound hole or it will get very boomy. About 30 cm away from the guitar in line with the 12th fret usually works well, but will vary depending on the guitar and the room, so experiment.

First, sorry about the confusing of posting three times in the different threads. I wasnt entirely sure which thread to put the topic in, and I was hoping to increase my chances of getting a reply.

Second, thanks for the reply back stevethefiddle! Very informative answer - exactly what i was looking for. Are there any resources on high pass filters on the net just so I can understand a little better why the audio is unsymmetrical? Is there an exact name for this problem "amplitude shift" or something. Looks like ill be recording from microphone from now on... its just that a clean recorded sound is alot harder to get when trying to control other noise from environment. In addition while strumming the pick I use occasionally taps on the pickguard, which is recorded through the mic. Oh well, guess there are pros and cons with any kind of recording setup.

Third, are there any general techniques Audacity has to make a song "brighter" or "crisper"? It seems the sound sometimes recorded from my mic/pickup is muffled/softened. I know there are ways to manually enhance/adjust the higher frequencies in the audio (using Equalization/Compressor), however I didnt know if there were any resources or general advice you guys had to suggest while Im trying to acheive a pure studio recorded sound.

Thanks Again!

allrightythan8 wrote:First, sorry about the confusing of posting three times in the different threads.

No worries mate, we encourage single posting only so as to keep the topics clear and reduce confusion.

allrightythan8 wrote:Are there any resources on high pass filters on the net just so I can understand a little better why the audio is unsymmetrical?

There is a situation that causes asymmetrical wave forms called "DC off-set". This is not what you have, though the description is rather similar. With DC off-set, the entire waveform is shifted above or below to centre line and is caused by a DC voltage being present in the signal - in your picture, you can clearly see in the quiet bit at the beginning of the track that the waveform is correctly located around the centre line.

As for why in your recording there are greater peaks below the line and less above, I don't know why - I've just noticed that it often happens with guitar pick-ups. It may not necessarily be due to high pass filtering, but high pass filters can certainly change the shape of the waveform that you see due to phase shifts. Try applying a high pass filter set to 24dB per octave and a frequency of 10 Hz to your recording and you will probably see the shape change quite dramatically, though the difference in sound will most likely be inaudible. You may find that it centralises the wave form, but in some cases it can cause the peaks to move on the other side of the 0 line.

The important thing is the presence of DC offset, but you don't have that problem.

allrightythan8 wrote:its just that a clean recorded sound is alot harder to get when trying to control other noise from environment.

Yes that's true. Fortunately it is very quiet where I live, but there are times when a sound proof studio would be nice.

allrightythan8 wrote:Third, are there any general techniques Audacity has to make a song "brighter" or "crisper"?

The type of microphone and the microphone position make a big difference. Condenser mics tend to have a brighter sound than dynamic mics. The AKG C1000S is a well known example of a small diaphragm condenser microphone that suits many instruments - it can also be used with vocals if you use a pop shield with it. A nice thing about the C1000 is that if you do not have phantom power available from your pre-amp/mixing desk, you can power it from a 9v battery.

If you have a mixing desk, you could try mixing the sound from the microphone with the sound from the pick-up. This can often give a good compromise solution.