Previous tracks bleed into the new one (Samson G-Track)

[Gale Andrews]

If you have an old slow machine with limited RAM and USB 1.1 ports I suppose you might have this choppiness issue at "higher" rates. What are your machine specifications?

• Processor: Genuine Intel @ 2.00 GHz
  Memory: 964 Mb
  USB:
  Speed: 12,00Mbit/s
  Version: 1,00
  Revision: 2,00

This is very interesting. Could these specs be causing a bottleneck? I got the computer (a laptop) in 2009, I did not realize the USB version was old.

The USB transfer rate is probably the limitation. The USB 2.0 specification allows for a theoretical 480 Mbit/s.

You could do with more memory, but not always easy to add on laptops.

I was suggesting that if you look on the playback side of ALSAmixer and you have a meter for the external mic then you may want to unmute it. Then if you recorded with an external mic and turned software playthrough off, you could hear yourself on time (without latency).

Great, thank you so much for the explanation. I got me a 3.5 mm mic and made the test. I unmarked Playthrough in Audacity, there is indeed an "external mic" bar in Alsa so I set it to 100, both in Playback and Capture just to be sure. Result: no sound comes through the headphones while recording the track. Also, I tried recording with the G-Track mic, sending its output through Alsa Analog, but again, no sound while recording.

So I guess my soundcard cannot do that. But then... what's the use of that 'external mic' bar?

You are looking in the playback section (F3), aren't you? It would only work to play the external mic input through the built-in sound card.

Yeah, recording at 32,000 is lame, and also, it produces the bleedthrough problem that brought me here in the first place. So what would be my options so I can listen to myself while singing? The USB version is going to be 1 no matter what I do, so should I get me a firewire device? I have no idea about Firewire, do you have any suggestion of models that work well with Linux?

I think it may be better to try something like these if your laptop has a PCMCIA or ExpressCard slot:
http://compreviews.about.com/od/buyers/ ... -Cards.htm

You've already spent money on GTrack and it should be far more useful than it is now.

Firewire seems to be falling somewhat out of favour for audio and I am unsure if it's as well supported on Linux as USB (that's an impression rather than a statement). But if you want to pursue it you can get slot cards that support USB and Firewire.


Gale

[kozikowski]

If I had to guess at it, I would say FireWire might make the problem worse. FireWire maintains perfect, constant bit-communications both directions at the same time. It's what allows us to easily boot and do production on external FireWire drives, a trick not available to USB until relatively recently because of its switching and traffic-copping. The upshot is the load on the computer would go up, not down. If you thought you had horsepower and speed problems before...

Koz

[steve]

The USB transfer rate is probably the limitation. The USB 2.0 specification allows for a theoretical 480 Mbit/s.

USB 1.1 (Full-Bandwidth) standard is more than adequate for bi-directional stereo audio, but that is not to say that the USB connection is not where the bottleneck is.
2 channels of 32 bit data at 44100 samples per second is less than 3 Mbit/s whereas full speed USB 1 is specified at 12 Mbit/s. However, USB 1 does not handle data in both directions at the same time - it alternates between transmitting and receiving, and transfer speed is CPU dependent. If the computer CPU is busy then USB 1 will wait until the CPU is not busy, which is devastating when recording.

There is also the question of how the computer handles the USB data. There are different classes of USB device and communication between the computer and the USB device should be different for each class of device. For example, for mass storage devices (class 08h, such as thumb drives), data transfer should be as fast as possible but is not time critical, whereas for and audio interface (class 01h) raw speed is less important but data transfer is time critical.

I think you mentioned somewhere that you are using Puppy Linux?
I tried Puppy some time ago, and while I agree that it is small and cute I did not find it to be well suited for audio use. Perhaps it is because Puppy is so lightweight that it does not have "optional" packages that help with efficient audio streams. I subsequently switched by old and under powered computer to Debian with Xfce and Jack, which then handled audio much better.

It would certainly be useful to find out for certain if the bleed through is a hardware problem in the Samson mic. A good test for that would be to try the microphone on a different computer to see if it is capable of recording 44100 / 48000 Hz without bleed through.

[Gale Andrews]

The USB transfer rate is probably the limitation. The USB 2.0 specification allows for a theoretical 480 Mbit/s.

USB 1.1 (Full-Bandwidth) standard is more than adequate for bi-directional stereo audio, but that is not to say that the USB connection is not where the bottleneck is.
2 channels of 32 bit data at 44100 samples per second is less than 3 Mbit/s whereas full speed USB 1 is specified at 12 Mbit/s. However, USB 1 does not handle data in both directions at the same time

FWIW I never found USB 1.1 to avoid dropouts on Windows XP even when recording without overdub (and it was worse on overdubs). Installing USB 2.0 solved dropouts even in overdub recordings, even though I understand 2.0 is still not bi-directional (USB 3.0 is bi-directional).

So if Puppy Linux is audio sub-optimal as I expect, but you want to stay with it, I still think you should give your laptop USB 2.0 (or 3.0) capability if you can, assuming there is not actually a hardware problem with the mic.


Gale

[Procne]

if your laptop has a PCMCIA or ExpressCard slot

Alas, on that aspect it seems I'm doomed: I checked and I only have a monitor entry, HDMI, 3 USBs and something called SD·MS/Pro MMC·XD.

You could do with more memory, but not always easy to add on laptops.

I checked the specs and I can upgrade up to 3 Gb. Would it solve by itself the USB 1 sluggishness?

I think you mentioned somewhere that you are using Puppy Linux?
I tried Puppy some time ago, and while I agree that it is small and cute I did not find it to be well suited for audio use. Perhaps it is because Puppy is so lightweight that it does not have "optional" packages that help with efficient audio streams. I subsequently switched by old and under powered computer to Debian with Xfce and Jack, which then handled audio much better.

Yup, point taken, I'll head to a different distro to see how it works, but for the record I'd like to add that I use a customization of Puppy called 'PupStudio', PuppyStudio is a distro supposed to be specific for audio and has real time kernel and all that stuff. Precisely, I chose it because it came with all the software required out of the box, so I could avoid the work of installing packages and focus on making music instead. So far I've recorded like 4 'albums' with it without problems (although, there is always the doubt: has the bleeding appeared recently, or it is only that I have realized recently? I was a complete audio illiterate when I started 4 years ago, and I've learned a lot...)

In any case yes, Puppy's leanness can sometimes be problem, so I'll try some of the distros that have been suggested in this thread and see if it makes any difference.

A good test for that would be to try the microphone on a different computer to see if it is capable of recording 44100 / 48000 Hz without bleed through.

Yes, I want to test that too, but I wont get access to a different computer until September.

[Gale Andrews]

something called SD·MS/Pro MMC·XD

It's a slot for a memory card .

I checked the specs and I can upgrade up to 3 Gb. Would it solve by itself the USB 1 sluggishness?

3 GB RAM can only help the general responsiveness of the machine, assuming Pup Studio can cope with it.

It won't help the USB sluggishness unless USB transmission at that speed is being held up by lack of RAM.


Gale

[Procne]

Hey guys, I just wanted to update the news about my mysterious bleeding affair. Short version, I installed Lubuntu and, under the same conditions and configuration, the bleeding is no more. So it probably was caused by the extreme leanness of Puppy Studio, perhaps skipping something important.

The long version: I shot myself in the foot while installing Lubuntu and had a computer meltdown. Who would have thought the install tutorial destroys your partitions so soon in the process, and without a confirmation message for curious souls? Luckily I had a backup. Also, as a side note, I find quite remarkable that Lubuntu did not recognize Puppy, instead it said that "there was no other os found". Where's the Linux solidarity gone?

Going back to relevant audio information, another thing I noticed in Lubuntu was that I could record with the G-Track at 48,000 hz, with no choppy effects! But the dream lasted very little; during my small initial test everything went fine, but then, when I recorded several voice takes for a project, I found later to my dismay that some of them sounded fine, but others became choppy from the middle point, or were completely choppy, apparently for random causes, but which seem to become more likely the more tracks you add. The USB 1 thing, I guess, so 32,000 will have to do, by the moment. Anyways, now I have a stable setup I can build on, so thank you all guys for your advice.