Not directly, no. Standard USB is a two-way communication between a single USB host and a target device. Some (very few) USB audio interfaces have direct analog outs or else insert I/Os that can be used to T-off to a second recording device while performing conventional capture to a USB (or FireWire) host, but this is unlikely to apply to the lower-cost units.

Making a safety backup recording of a live event is something that stand-alone recorders such as the Alesis HD24 are very good at. Stories abound of how HD24 tracks have saved the day when the primary recording laptop has thrown a wobbly during the show. However, back-up recording using this type of device needs access to the line-level signals in real-time, and in most of the simpler audio interfaces these are buried.

I don't think USB has that capability. Firewire devices can though. I have a Fire Studio that has two firewire ports and can send one to a laptop and another to a external hard drive.

Here is a couple of options and a couple of thoughts.

I almost always roll some kind of safety backup. To enact a proper backup, you would need a pair of audio distribution amplifiers. Each input then offers isolation with multiple output amplifiers. Which are then distributed between a pair of multitrack recording devices i.e. computer and/or stand alone recorder. The distribution amplifiers are not always necessary. Most outputs from most mixers, that offer at a +4 average output level can load it into 600 ohms. Meaning that all you really need is just some Y style patch cords. Because most equipment inputs today are usually around at least 10,000 ohm input loads. Two in parallel would be 5000 ohm loads. Four in parallel would only present a 2500 ohm load, making an output source that's capable of loading into something as low as 600 ohms, a total walk in the electron Park.

There is no problem with plugging in a non-matching set of USB computer audio devices into a single computer, which I do all of the time. But that does not provide for safety backup. Safety backup can only be accomplished on a separate device that would have no interaction with the previous stage, should that other device fail and short out. Which is why you really cannot do a safety backup on a single computer. Two computers? No problem. One computer and a multitrack machine? No problem. One computer? Then you have no reason to run a backup if that is your only recording device. Because if your computer crashes, so does your backup. That's almost like leaving your spare tire at home to save gas on your vehicle by lightening the load. When ya get a flat tire, then you need a toad job home in order to change your tire. Kind of defeats the purpose you know? So no advantage to having that spare tire, elsewhere.

So if I don't have a second 24 track machine available? My backup to the 24 track may be nothing more than a stereo reference mix? And which might actually still be going to an old 16-bit, 44.1 kHz DAT machine? Because it's still usable and you still have something of a backup. Not ideal. Or what happens if you have a dropout? You'll need to replace that dropout. And so you have the backup safety.

In another peculiar way, I lessen my insecurity by first going into the digital multitrack machine. At the same time, the digital multitrack machine fees a desktop computer audio interface via light pipe. It's that computer recording that the customer will walk away with on a hard drive. Nevertheless, the multitrack machine has the same recording on its internal hard drive in a different file format not compatible with any software. And with which would make your client very upset if you are to deliver that hard drive to them. And if I did not stream it in real time, from the recorder, into the computer, it would require me to remove the hard drive from the multitrack machine and then transfer it after the fact, through the computer to a FAT 32 OR NTFS formatted hard drive anyhow. And so the real-time stream to the computer saves time and hassle.

Computer data streams and computer protocol is quite foreign to that of analog signal routing and patching. Computers don't work like that. So ya can take the analog output from one of those USB devices and see the analog input to another, connected to yet a second computer. But at the other computer blows up and you go to restart it, you'll lose that feed. So it's not a suggested way to do it. The same with my multitrack machine. Which is another reason why I will simultaneously create a quality broadcast style, stereo mix as yet a third backup.

When you watch the president of the United States speak from the White House, it is through a dual if not triple fully redundant system. And where you will also see numerous television network news anchors wearing a pair of LAV microphones. That's dual redundancy through a single console. And probably because they know, the console won't go down but the microphone could likely crap out. And they do. You've heard it happen. Not pretty. And where the individual newscasters in the field are wearing but a single LAV microphone, there may still be a shotgun secondary microphone mounted right on the camcorder feeding the other available channel and there usually is. And where condenser microphones do not do well through inclement weather, the dynamic microphone will. And so you'll see that they have both. One on their lapel and one in their hand.

I had a serious failure on a job a couple of years ago. I should have brought the 24 track recorder for this eight track job. But that is screwed into the rack with everything plugged in. One big pain in the backside. So I took the desktop computer out with the eight track audio interface. I also had two laptops with me both with stereo USB audio interface's. The soundtrack of the orchestra prior to the show went well. The stereo mix was also going to both laptops. Just as the show started and within the first 30 seconds, the desktop computer blew up. OMG no. So then, I shut down one laptop and grabbed that USB stereo interface. I had to stop the other laptop and plug that USB interface in. Then I had to configure the software for 4 channels of capture which wasn't enough. I had to stick another couple of channels into the onboard horrible laptop soundcard input. And reconfigured the API 3124 mixers to provide for discrete outputs and a stereo mix of the other inputs. A huge compromise. Thankfully, the failure occurred on the least important piece of music as opposed to the new original piece that was being debuted. So while I lost part of this performance recording, I was still able to manage to capture the most important part of this performance, I was able to capture the most important part of this debut performance thanks to my roster of backup stuff. And I always bring out nearly double what I know I'm going to need. Because frequently changes are made or improvised at the last moment and I always want to be prepared.

This is another reason why people do not like doing on location recording. IT'S A LOT OF HARD WORK, frequently in and above anything else you have ever experienced doing. And all these snotty nosed kids coming out of recording schools, just want to sit on their big fat duffs and play with knobs and dials. Nobody wants to work for a living. And when those morons are faced with having to make a live recording, they go about it like they learned to do it in the studio. And that frequently doesn't work. They'll put up expensive studio condenser microphones and not understand why they cannot obtain a good recording or balance? DUHWell that's because they really have no idea what they're doing. They have no idea or concept what are the proper microphones to use. And these dumb MF's are teaching this stuff. You're paying a lot of money for a lot of bad information from the blind who wants to lead the blind. And I've had to teach the teachers. So I feel that a lot of the recording schools are a huge waste of money. I'm sure Full Sale has changed their tune on ribbon microphones today. But that's not what they were teaching 10 years ago. They were so bad and so noisy that virtually every manufacturer of quality microphones today are making these ribbon microphones. And they didn't 10 years ago. So what kind of state of the art are those schools teaching anyhow? They are not teaching any art. They all record with their own eyes and not with those other two skin flaps on either side of their noggins. I guess because their ears don't have any eyeballs, they can't trust them? Because it's obvious to me that they don't know what to listen for or what they are listening to. So I call these guys Cub Scout engineers. They're still learning how to tie their shoelaces.

Let's hope they know how to zip their flies up, without being instructed which direction to go?
Mx. Remy Ann David

No you can't use any USB unit onto 2 computer at the same time. Don't know why you want to do that.

If it's for safety, have:
-a battery backup (uninterruptive power) = so if power fails, you have time to save and shutdown you pc
-redundant HDD (in Raid1 or Raid5) = the data is replicated while you record, so if a HDD fail your data is still on the other one.
-External backup solution that you bring off site (you transfer the data after the session is done) = if the studio burns you still have the data.

Other than that, making a cluster of 2 or more computer is somehow too much paranoia and ressources hungry ;)

If it's only for duplication, you can have the computers network connected (crosswired or with a switch) and have a duplication software of some kind, but it's gonna take some resources the DAW might need to work properly.

You can also have 2 audio devices connected to your 2 computers. you can then record the same signal splited in the mixer or a snake and wired to the 2 audio devices.

If you're only doing two tracks at a time, you can go spdif from your interface to spdif in the other computer's sound card. The signal remains digital so, there shouldn't be any loss in quality. You might need to install asio4all just to minimize latency issues.

No you can't use any USB unit onto 2 computer at the same time. Don't know why you want to do that.

Because I have 2 PC's running the exact same DAW - one is mine and one is a friend's that I am currently collaborating with, and I didn't want the hassle of saving OMF files or dumping to flash or CD.

I thought perhaps I could track to both PC's via a USB "split" or something similar in adaptation...

And the original question was already answered, but thanks anyway.

If you're only doing two tracks at a time, you can go spdif from your interface to spdif in the other computer's sound card. The signal remains digital so, there shouldn't be any loss in quality. You might need to install asio4all just to minimize latency issues.

Thanks Hue... the session was multitrack, 12 tracks recorded at once... and even if was just a 2 mix, while my 16 channel I/O does have SPDIF out, neither computer has a dedicated PCI card for audio, so, no SPDIF I/O. on either machine.

I was just trying to save time. No biggie. I ended up saving the file as an OMF and dumping it to a flash drive.

Just a note. Many on board sound cards have spdif I/O. Not all of course but many do. Usually all you would need is an RCA to 1/8" cable. Of course this is entirely useless information but hey. I specialize in that.

One PC is a laptop, Hue, so it's got your obligatory cheap-assed Realtek internal SC that came resident, with an analog 1/8" stereo jack for output, and the same for input.

The other is a desktop PC that at one time did have an M-Audio, 2 in/2out analog RCA with SPDIF, but I had to remove that card - not just disable it, mind you, but actually remove it from the MB, because it wasn't working and playing well with the Tascam 1641 USB external I/O.

But I do appreciate your suggestions. :)

-d.

While you took out that M-Audio PCI card-based unit, because it didn't play well with your other devise, did you ever have the ability to try a different PCI slot? Sometimes just changing that card to another PCI slot can solve all of those problems because of the IRQ allocating. And I've gone through that numerous times in the past with my earlier desktop custom machines. So a radical performance might be noticed with the PCI card in one slot but when moved to another slot, the problems went away. So ya might want to give that unit another go? The PCI stuff really should not be interfering with USB stuff. But if you only have the one PCI slot available in there aren't any others, I can certainly understand the frustration. I have quite frequently run more than a single audio device upon a single computer without problems.

Some of the other problems could be the computer tweak itself? And/or the need to disable devices, not being used such as others serial or parallel ports. Freeing up other IRQ's and others' sources for the computer. That along with disabling virus scanners and other background software updating and security updates can certainly wreak havoc when trying to run more than a single audio interface device. Which may require you to free up some resources within the operating system? Some of this is done in the startup bios. Other items can be disabled in the device manager. From the start, run menu, you should also plunge in MSconfig. Then you hit enter. Then you go to start up and uncheck all items you feel that are unneeded. In control panel to also select scheduling and dispose of most scheduled functions if not all. Google and flash updating should also be disabled. And then you will select the services tab and also disable any services at startup that are not needed. It will just take slightly longer to launch those programs when you disable that which is not Microsoft necessary. And where you can check a box to hide all Microsoft services leaving only the ancillary service devices that are preloaded on startup. And adjustments of the amount of buffers and how long the buffers should be may also be necessary. Sometimes it takes us days, weeks, months to properly tweak up a computer for nearly flawless performance for audio production purposes. It's a juggling act for sure. And you shouldn't have needed to pull out that card? Though that is frequently a quick way to solve some of these compatibility issues when you are not prepared or unable to work the problem through. And you wouldn't be the first to have this have happened to you. It can be a frustrating hair pulling experience no doubt. And I've run into these same kinds of problems in building up my own custom desktop machines. And with those a simple change in reordering of the PCI cards solved the problems but it certainly wasn't easy getting there. And where I also found myself disabling parallel ports since all of my printers today are USB. Same for the serial port as I do not need a serial mouse anymore. It wasn't so much of a juggling act as it was those spinning plate dishes on top of vertical sticks which I think is a closer analogy LOL? Remember those acts on shows like Ed Sullivan? I guess it's rather passé today since we have Cirque du Soleil? Where they replace those plates with people LOL. I guess if you want something done right, you do it yourself?

So take this out for a spin.
Mx. Remy Ann David

DonnyThompson, post: 401732 wrote: One PC is a laptop, Hue, so it's got your obligatory cheap-assed Realtek internal SC that came resident, with an analog 1/8" stereo jack for output, and the same for input.

The other is a desktop PC that at one time did have an M-Audio, 2 in/2out analog RCA with SPDIF, but I had to remove that card - not just disable it, mind you, but actually remove it from the MB, because it wasn't working and playing well with the Tascam 1641 USB external I/O.

But I do appreciate your suggestions. :)

-d.

I have 4 pci M-Audio delta card in my pc. I went crasy to make them work when migrating to Win7 x64. In the end the asio drivers were the cause.. Yes, everybody says Asio is much better for latency and all. But I now have no crash nor latency problem anymore, since I use MME drivers (with sonar x2)

So I second Remy, another pci slot and many driver tests might save that card ;)

I appreciate the suggestions, gang.

And at some point I might look at reinstalling the card... maybe. The quality was what one would expect from an $89 PCI audio I/O, ... it's not as if it was an Apogee or anything, so I wasn't all that broken up about having to remove it from the PC to get the Tascam 14 ch I/O to work without glitches.

And... even if I did jump through the necessary hoops and reinstall it, it still wouldn't have given me the routing that I had originally wanted, which was 12 discreet tracks to 2 PC's at the same time ...

So yes, while I could have sent SPDIF out of my Tascam I/O to the SPDIF on the PCI, I was looking at much more than just a backup 2 mix.

And as a final note, fwiw, the Tascam performs much better in Sonar using Asio4All drivers - as opposed to the default Tascam drivers that were included (and suggested) on the original install disc for the device.

-d.

Donny,
The only way I see you could do what you want is to buy another soundcard for the laptop and use a split snake to send the signals to both computer. So they are both independant fully functionnal DAWs and both capture the same sources. Could be a great solution for recording a very important live show !

Other than this, copy everything on a external HDD or transfer the files through a network connexion.

Sorry sometimes a law can't be bent ! ;)