Loss of Signal with Firewire?

I have an Alesis Mutlimix 8 channel firewire mixer that I am using with Audacity on a PC running XP sp 2, etc. My VU/input meters register the signals fine, but the visual readout- the sinewave of the signal that is the visual component of the Audacity file display is very small- it leaves a lot of head room. The sound is fine over headphones or when played on my speakers- it is just not as strong “visually” as a direct L/R feed into my sound card and looks like very small blips on the display instead of the clearly identified wave patterns one usually sees on any digital recording graphic interface. IS there a problem with the firewire interface and how the signal is graphically represented or do I really have a weak signal coming from the mixer? Has anyone else had this problem? It is the same on both my desktop and my laptop- so I assume the problem is with the firewire feed or the program’s (Audacity) ability to register it graphically. A few more circumstances:

The effect is the same whether I’m recording one, two, or four channels.
When I do a direct out from the mixer into my sound card using a stereo RCA 1/4" jack, the signals are normal.

Again, because I can hear the sounds fine and the input meters register normally, I can only assume the problem is in Audacity’s ability to take the firewire signal and graphically represent it. But, when I take that recording that has a minimal representation, then amplify it up to point just below clipping to it looks like a typical sound wave, it also sounds fine and undistorted. So, the sound is both clear but there is plenty of head room.

Any thoughts on this?

Thanks in advance.

As with USB interfaces, Firewire interfaces do not use the Windows Mixer, but they may have a level adjustment in the Windows Control Panel.
There may also be a level adjustment on the unit itself.
The recording level slider in Audacity may have some effect (but may not do anything - it seems to depend on the drivers)

Again, because I can hear the sounds fine and the input meters register normally, I can only assume the problem is in Audacity’s ability to take the firewire signal and graphically represent it.

This is not true. The problem is that the Multimix is spitting out a digital signal that’s well below 0dB. This is either because of what Steve is talking about (the drivers or OS settings), or you have one of the knobs on the Multimix turned down quite a bit.

The loss of signal problem is resolved and yes, you were right- it was one of my input dials not at the correct level. The firewire works fine.

However, I have one more kink to work out before my firewire/Audacity dreams are achieved!! Theoretically, the mixer is not only sending out up to eight independent channels, but a stereo feed of the mix- i.e. I should be sending how ever many channels I’m using plus 2 channels (the L/R mix) on top of that. This is what the Alesis manual says, but Audacity only registers the eight or portion of the eight that I am using. If I set the preferences to two over the amount of channels that are sourced, I get an error message saying that the input doesn’t match the device, etc. I know this is probably an Alesis question, but if you have any ideas or experience with this issue, always appreciated.

Smashing Super :smiley:

I’ve come across this sort of thing before, but it doesn’t mean that with an 8 channel interface you can get 10 channels (otherwise they would call it a 10 channel interface) but it means that it is an 8 channel interface and you can send a stereo mix back the other way for monitoring. (the Mackie firewire interface does this, but I don’t know how it is implemented on the Alesis)

I’d bet those extra two channels are listed as a different device. If that’s the case, then Audacity won’t be able to access it at the same time as the other inputs. But I don’t know how the drivers are set up, so I can’t say for sure.

Okay- here is my update on the Alesis Firewire Audacity situation. The 8 channel firewire interface is actually 10 channels. It has the 8 channels of individual input plus a stereo L/R mix. In order to get the mix though, you have to have all ten channels selected in Audacity preferences. So, no matter how many channels you are actually using, (i.e. I’m using only 4 channels presently) you must set audacity for 10 if you want to get the mix. And, because the mix is where any effects that you are doing in the mixer are sent to the recording, if you don’t have the stereo mix, you won’t get the effects in your recording. (This means that what you are recording for each individual channel is the signal that is coming into the mixer- what gets recorded is not affected by post-effects or volume in the individual channel- except for what you set the input gain to for that channel.) If you set Audacity for 9 channels, you’ll only get one channel of the mix. If you set it for 11 or more, you’ll get an error message that says the device doesn’t match the input, etc. Incidently, the stereo mix will be the first two channels when preferences are set correctly to 10 and it is a stereo track, not two mono tracks. But, until you hit 9 channels (8+1) the channels will be in order, (i.e. channel 1 is top of the screen, 2 next , etc.) It would be great if there were a way to set it so that the stereo mix was always on top and then what preceeded was the number of channels you are using in order- which is what my original assumption was regarding the digital interface. So, to boil it all down- it seems at least with my mixer- you need to send all channels even if nothing is on them in order to get the mix recorded. I will follow up on this with Alesis.

This is great news for me since I’ve discovered that, in fact- against the naysayers of both Audacity as a serious mixing program and firewire as a reliable interface- the mixer and the program work together exactly as I wanted them to. It is a bit of pain to have to stream the 10 channels while I record, but I can delete the empty channels when I edit if I need the visual space to add any layers before I mix down to stereo. Those of you with 12, 16, and 24 channel mixers- may want to get a bigger monitor!

Thanks for the info Kleunk, I was wondering how Alesis handled those extra two channels.

I notice that the multi-mix offers two recording options; “MultiMix Main In” and “MultiMix Channels In” - What’s the difference between these two?

Hello everybody.

I hope somebody will again visit this thread.
I’ve similar problem with a new Helix Board 12 Firewire Mk II.
when I record from REC OUT of mixer directly into the MIC IN, then I have a good signal. if I record through firewire, then the signal is still there, but it is about 30 to 40% lower: VU are OK - even if smaller - and sinousoidal shapes are much smaller. and also the level I hear from EARPHONE OUT of the lap top is fairly lower.

I think it is the same problem as Kleunk wrote, but I couldnt’ understand how he solved it … :blush: :blush: :blush:

what you mean by:

where do I have to do this adjustment?

the input dial was on your mixer, or was on Audacity?

AS a last question (sorry but I’m not very much familiar with Audacity … :slight_smile: :blush: ) the HElix Board has 8 channel plus 2 mix L/R (as the ALesis). can you please explain step by step ( :blush: ehm …) what I have to do to set more channel (otherwise I get same error message as you wrote)

sorry for bothering you but since one week I’m troubling on these issues …

thank very much in advance

Alex from Italy

The signal level that you get from the MIC in (which you should only use with a computer microphone and are typically poor quality) is not a reference level - it is dependent on the input level slider in the Windows Mixer. For using the Firewire interface, make sure that you have a good signal level on the mixer and push the master slowly up to “0”. By the time the meters on the mixer are pushing 0 dB, you should have a good level in Audacity.

Go to “Edit->Preferences->Audio I/O” and set the number of channels in the drop down box.

You lucky people with firewire mixing desks :slight_smile:

Thank you for your prompt reply, stevethefiddle,
in other words the level I get analogic with the MIC IN and the level I get digital via firewire are not comparable? :question:
but actually if I push the mixer slide up to 0 dB (with firewire connection), still I have not the same level as with MIC IN connection, and in order to have the same level I have to increase LEVEL and GAIN on the mixer with resulting higher ground noise … :neutral_face:
anyway I will try further.

regardins multiple tracks recording, I already did what you suggest, but I do not understand how to assign each audacity track to each channel.
moreover when I try to record, I get the message"Error at device opening. check device input setting and sample frequency" (this is a translation of what i get in italian).
maybe I have to enable somewhere the multipletrack recording or the channel assigning.

thanx for your attention :slight_smile:


Audacity would like to have a signal close to, but not exceeding 0dB. However some audio hardware will start to clip the signal (a kind of distortion caused by the top and bottom of the signal being chopped off) below 0dB. It is therefore best to aim for a signal as close to 0dB as possible without introducing any audible (or visible) clipping.

Your on-board mic input uses completely different hardware to your mixing desk input, so there is no direct relationship between the two, other than that they feed an audio signal to Audacity.

Most mixing desks these days have multi-coloured LED meters. Green shows there is a signal,then it turns orange as the level increases, and finally red. It is quite ok for the meters to show orange, but you should avoid red as this indicates that the signal is being clipped.

I don’t know about you particular desk, but usually there is a way of metering the “Pre-Fade Level” (PFL) - this is the signal level of any one channel of your mixer, after going through the EQ. section, but before the “level” fader. If you have this facility, turn the master fader down fairly low and adjust the “gain” (sometimes called “trim”) so that the pre-fade level shows a strong level (up to the top of the green and sometimes touching the orange on the meter). Then switch to normal metering and adjust the master fader so that the meter again shows a strong signal. The signal that Audacity receives should now be at a good level, though you may need to tweak things a bit to get the optimum. (avoid driving anything into the red though).