low volume level in MP3

[steve]

Oh heck, I was afraid it might be something like that.

Let's just confirm - Everything is working OK when you use Audacity 1.2.6 (except for the playback level of MP3s that you make with Audacity)?

Keep a note (pencil and paper) of everything you change while we are testing so that you can put everything back as it was (just in case we mess up).

Again to confirm the current situation, when you open Audacity, you get an echo when you play the keyboard?
You don't need to start recording or anything, just opening Audacity causes the echo to occur?

Click on the "Transport" menu in Audacity and find "software playthrough" (near the bottom of the list). It should be OFF (not selected).
In the same menu find "Overdub" - it should be ON (selected).

[Brenthard]

Click on the "Transport" menu in Audacity and find "software playthrough" (near the bottom of the list). It should be OFF (not selected).
.

Case solved, thank you. I had "software playthrough" on, this seems to have caused the loop.

However, I immediately noticed a new problem , when I tried to export as MP3. It worked, but now there is a noise during playback, that never was there when I used 1.2.6. Anything I can change?

[steve]

when I tried to export as MP3. It worked, but now there is a noise during playback,

Not really enough information to go on. For example:
You mean when you play back the MP3 file?
What sort of noise?
If you generate silence and export it as an MP3 do you get the noise?
If you generate a tone and export it as an MP3 do you get the noise?
Do you hear the noise when you play the original recording in Audacity?
Do you hear the noise if you import the MP3 back into Audacity and play it?

Please add your own description and details of the problem.

[Brenthard]

when I tried to export as MP3. It worked, but now there is a noise during playback,

Not really enough information to go on. Please add your own description and details of the problem.

1. You mean when you play back the MP3 file? Yes.
2. What sort of noise? The sort of background noise that was characteristic for old time tape recorders (specifically when DOLBY was not on)
3. If you generate silence and export it as an MP3 do you get the noise? Yes.
4. If you generate a tone and export it as an MP3 do you get the noise? Yes.
5. Do you hear the noise when you play the original recording in Audacity? No.
6. Do you hear the noise if you import the MP3 back into Audacity and play it? Yes.

As I said, I don't have this with 1.2.6.

[steve]

If you export as a WAV file, does that sound OK?

Before you export, look in the bottom left corner of the main Audacity window. There's a number in a box and it says "Project Rate (Hz)" above it. What's the number?

When you export as an MP3, on the Export Dialogue screen (where you enter the file name), there is an "Options" button.
Click on that button. What options are selected?

[Brenthard]

If you export as a WAV file, does that sound OK?

Before you export, look in the bottom left corner of the main Audacity window. There's a number in a box and it says "Project Rate (Hz)" above it. What's the number?

When you export as an MP3, on the Export Dialogue screen (where you enter the file name), there is an "Options" button.
Click on that button. What options are selected?

No, the same with wav. Project rate 44100 kHz. Options:

bit rate mode: Constant
Quality: 128 kps
Channel mode: stereo

[steve]

This doesn't make sense. An exported WAV file should sound virtually identical to playing the Audacity track.

Do you still have Audacity 1.2.6 installed? If you do, could you check that the problem is not also occurring there.

[Brenthard]

This doesn't make sense. An exported WAV file should sound virtually identical to playing the Audacity track.

Do you still have Audacity 1.2.6 installed? If you do, could you check that the problem is not also occurring there.

Let's see if you can hear the difference. If I have succeeded with uploading there should be two files with 15 s of silence, one recorded with 1.2.6, the other with 1.3.12 (both mp3). At least on my computer, there is a noise in the 1.3.12 file.

[steve]

Yes I can hear it. I thought you meant much more noise than that.

There is noise on both of those samples, though the noise on "silence 126.mp3" is noticeably less.
The noise is created due to the conversion from "32 bit float" format in Audacity to "16 bit integer" in the exported file. If the audio is recorded at a good level then the amount of noise should be insignificant and should actually improve the overall sound quality by reducing "quantising" errors. The process is called "dither" and is a similar idea to how graphics are made to look smoother and less "blocky".

The "dither noise" is made significantly worse due to losses in the MP3 encoding process and is worse in the "silence 1312" sample than it needs to be due to the type of dither that is being used and the type of MP3 compression.

If you are so concerned about the sound quality you should really be using a higher quality than 128 kbps CBR.

First let's look at the dither settings:
"Edit menu > Preferences > Quality"
I expect the dither setting is currently on "shaped". For MP3 export I would recommend either "triangle" or "rectangle". Triangle is probably a bit better while there is sound present (non-silence) but rectangle will produce no noise at all when the track is totally silent. Generally I prefer triangle, but if you find the noise during "silence" really distracting, give rectangle a go.

Next the MP3 settings:
On the Export dialogue screen there is an "Options" button. If you have "MP3" selected as the format then the MP3 compression settings are available in the "Options".
For good quality stereo music I would recommend that you use "Preset: Extreme"

Attached is a short MP3 sample from Audacity 1.3.12 with dither set to triangle and MP3 encoding with Preset: Extreme.
The last second was total silence but now has a tiny bit of noise, but I doubt that you'll find it distracting.

[Brenthard]

I followed your instructions, Steve, and it helped. Thank you! It is always very annoying when you are upgrading your audio system, only to found that the sound is getting worse - but now I seem to have the right settings. I also tried the suggestion of using the "amplify" function, seems to be exactly what I needed. (As far as I can see, it is impossible to adjust the recording level directly, perhaps it has to do with my sound card.)

I do perhaps get into extreme with my demands for a pure sound now and then. In fact, I recently bought a separate headphone amplifier in order to get rid of the (slight) noise I heard when I used the headphone outlet of my computer speakers. (This also worked.) The probelm with digital music making is that the sound system has to be very good, since it shapes the accoustics of the vst instruments.