M-Audio Profire Lightbridge UNUSABLE on internal clock

[soundmandoug]

Hi folks, please help me with a very frustrating problem;
I've been trying to get an M-Audio Profire Lightbridge working with my DDX3216 and laptop, and am seeing consistant problems with audio quality and clock sync-ing. I've tried three Lightbridge units (I got two off ebay and my mate has one) and two computers - all below described behaviour is consistent across units and computers.

The lightbridge unit is unusable when sync'd from internal clock. On playback of a (known good) audio source (24bit PCM 44.1Khz) the playback fades out every few seconds, with a burst of digital noise. This is true even if the unit is not connected to any other devices other than the computer via the firewire cable (and powered from the cable) - listening through the headphone out on the lightbridge unit.

The above is the same whether I play back using Reaper via ASIO, or Audacity via MME or Windows DirectSound.

When sync'd from the external SPDIF or ADAT (from the DDX3216) the unit does play back, but it's really hard to get it to play back clean with no clicks or pops. On the laptop I had to get an expresscard TI chipset 1394 interface to get (mostly) clean audio. On the tower system (4 core modern AMD with NEC chipset 1394 interface) it's clean almost all the time (unless I reduce the ASIO buffer size down to 64) but still seems fragile.

If I try recording, frequent clicks are recorded onto the material (I can see the peaks in the displayed waveforms in Audacity or Reaper) unless I work very hard with buffer sizes and adaptor type.

I also have an M-Audio 1814, which has 8 ADAT ins and outs. This unit works flawlessly on either system with smallest ASIO buffer size (64) with all 1394 interfaces including the motherboard interface on the laptop (Ricoh chipset), using the same cables and interfaces as above.


I'm using good quality, fairly short 1394 cables. With laptop the devices have to be powered from external PSU, as neither interface (motherboard - 4 wire - or expresscard adaptor) supply cable power.

Both computers run Windows 7 ultimate, 64bit.

Has anyone else managed to get M-Audio lightbridge units to work successfully on Windows with internal clock, or has seen the above issues??

Doug (Very puzzled)

[doctor]

Hi folks, please help me with a very frustrating problem;
I've been trying to get an M-Audio Profire Lightbridge working with my DDX3216 and laptop, and am seeing consistant problems with audio quality and clock sync-ing. I've tried three Lightbridge units (I got two off ebay and my mate has one) and two computers - all below described behaviour is consistent across units and computers.

The lightbridge unit is unusable when sync'd from internal clock. On playback of a (known good) audio source (24bit PCM 44.1Khz) the playback fades out every few seconds, with a burst of digital noise. This is true even if the unit is not connected to any other devices other than the computer via the firewire cable (and powered from the cable) - listening through the headphone out on the lightbridge unit.

The above is the same whether I play back using Reaper via ASIO, or Audacity via MME or Windows DirectSound.

When sync'd from the external SPDIF or ADAT (from the DDX3216) the unit does play back, but it's really hard to get it to play back clean with no clicks or pops. On the laptop I had to get an expresscard TI chipset 1394 interface to get (mostly) clean audio. On the tower system (4 core modern AMD with NEC chipset 1394 interface) it's clean almost all the time (unless I reduce the ASIO buffer size down to 64) but still seems fragile.

If I try recording, frequent clicks are recorded onto the material (I can see the peaks in the displayed waveforms in Audacity or Reaper) unless I work very hard with buffer sizes and adaptor type.

I also have an M-Audio 1814, which has 8 ADAT ins and outs. This unit works flawlessly on either system with smallest ASIO buffer size (64) with all 1394 interfaces including the motherboard interface on the laptop (Ricoh chipset), using the same cables and interfaces as above.


I'm using good quality, fairly short 1394 cables. With laptop the devices have to be powered from external PSU, as neither interface (motherboard - 4 wire - or expresscard adaptor) supply cable power.

Both computers run Windows 7 ultimate, 64bit.

Has anyone else managed to get M-Audio lightbridge units to work successfully on Windows with internal clock, or has seen the above issues??

Doug (Very puzzled)

Hi Doug,

As far as I understand, here is the forum for the hardware technicians.
With questions that can be defined as “usage” it makes sense to address to the more suitable forums. Try for example the following:

Recording Engineering
Recording - Engineering & Production

Prosound Web
LAB: The Classic Live Audio Board

Studio-Central Forums
Studio-Central Community • Index page

[Steve Conner]

Sounds like a driver issue. Are you running the latest Windows 7 drivers? M-AUDIO - M-Audio Releases Qualified Drivers for Windows 7

[soundmandoug]

Yes, I tried with both the latest (6.0.4) and first windows 64bit (6.0.1). Behaviour same with both. I agree it does sound like driver, although M-Audio use the same driver for the 1814 unit and the Lightbridge. You can even have them connected together, when the ASIO driver concatinates all the devices so the DAW software can use all ports on all devices simultaneously. Quite cool really.

I originally thought this was a hardware problem (hence airing on this forum) but it's increasingly looking like logic (driver) issues, unless there's a known weakness with older lightbridge units (all the ones I've tried are from ebay).

Further to my post earlier, I've been doing some systematic testing today and narrowing down the problem. It seems that the fading out/noise burst on internal clock is do to with sync issues with the desk (DDX3216), even when the desk is having NOTHING TO DO with the signal path - I'm outputting a PCM stream from the computer to the lightbridge unit, listening on the headphone socket on the unit, with the unit internally clocked. The computer is outputting the stream to the "analog" device on the lightbridge, which uses an internal DAC to the analogue ports and headphone port.

It just happens to be connected via ADAT optical cables to the desk, which is also locally clocked. Is this right, that just having a clock source present at one of it's inputs causes the unit to interfere with it's internal clock?

Doug

Anyway, I wasn't aware that this forum was focussed on hardware issues, so I'll move this to another, as suggested by "doctor" (thanks doctor, for your reply and suggestions of forums).

[Steve Conner]

Might be worth trying M-Audio's own support forum too?

If you have the unit set to internal clock, it ought to ignore the clock information from the ADAT port. Audio transferred over the ADAT interface will either be muted altogether, or suffer from clicks and pops because it's not synchronised.

It is possible to get a clock loop if you connect two ADAT or SPDIF devices together in both directions, and set both to external clock. This can cause really wild behaviour. One device has to be the clock master, set to internal clock. So, make sure your DDX3216 isn't set to get its clock from the ADAT input.

[soundmandoug]

Further to my previous reply, I'm wondering whether the internal oscillator on these units could be drifting. I've opened the unit up and it only has a single crystal, at 2.5xxx MHz (can't remember the exact frequency). If that clock drifts, it could cause all the problems I'm seeing.

Doug

[Steve Conner]

I think it's unlikely that all three Lightbridges are suffering from the same drift, though.

[soundmandoug]

THanks for all your replies. I've just registered on the M-Audio forum and will be trying there. I'll report back if I get any joy, just to add to the knowledge level :-). Looking through the docs again, it seems that the unit believes it's getting conflicting clock sources (mismatch condition) but the only thing connected to it at the moment is the firewire cable and the analog outputs to headphones and/or amp. No other digital ins at all.

So, let's see what the M-Audio boys have to say :-)....

[Jag]

It does sound like a possible driver issue.


Hovever,

It just happens to be connected via ADAT optical cables to the desk, which is also locally clocked. Is this right, that just having a clock source present at one of it's inputs causes the unit to interfere with it's internal clock?

I seem to vaguely remember having a similar issue several years ago. At that time, I was using a couple of hard disk recorders (Mackie), a Yamaha digital console and my older PowerMac. If I recall, the only resolution was to use external clock on all except one, which was set internal and functioning as master clock for the rest. Even though there was no logical reason for the digital clicks and pops, since I was using the analog connections for the audio, syncing all units to the same clock was the only thing that worked. I was using the Mac and Yamaha for various digital control functions so, I assume that at least one of the units was seeing another clock and decided that there should be sync issues.

Details are fuzzy as it was some time ago but, I recall having to try almost every combination of slave and master clock before I found one that worked.

Sorry I can't remember more.