Firewire limits?


I have an iMac i7 quad core, to which I connect two hard drives via Firewire. One is for audio files, the other for samples. (My RME audio interface is connected via USB.) I'm interested in purchasing Universal Audio's UAD-2 accelerator. I'm wondering, though, if this is practical. Would I be asking too much of the Firewire bus with three connected devices? On the other hand, most of the plugins I'd be running through the UAD-2 would be functioning only during mixing, in which case any sample-based instruments would have already been converted to audio and the instruments themselves no longer running.

Obviously, this wouldn't be an issue on a Mac Pro, but does anyone know if this would work on an iMac?


I'd contact UA directly and ask. I know it can be done, but things like max tracks you could use before you ran into issues would be something they can answer.

Q: there are a number of Thunderbolt to PCIe solutions out for about $1000 for a 3 slot (Netstor being one I would suggest you look at). Why not buy one of these and make your system expandable? I know it's an extra cost, but you could also add a sata card and add more drives at a faster rate than FW 800.
Thanks for the reply George. My iMac is 1.5 years old and, therefore, pre-Thunderbolt, so I can't make use of your hardware suggestion. I'll follow up on your other thought and contact UA.


I have the same Mac and was wondering about putting the UAD, an audio drive, and a MOTU 828-3 all on the same FW 800 bus. From some googling, you can see the effective throughput for FW 800 under good conditions is about 550 MHz. So, in theory, if the signal has to go from the audio interface, to the Mac, back out to the UAD, then back into the Mac, you ought to be good for 24 stereo channels at 24/48K which would need about half the 550 MHz. In my case, the MOTU runs at 400, so that would put me closer to the limit. Using two drives on the bus would complicate things

BUT --- this is all theory --- I haven't tested it.
Thanks to both George and Bayswater for their thoughts. Unwilling to take the expensive risk of acquiring the UAD Satellite in order to "give it a go and hope," I'll pass for now. Perhaps the next Mac will be a Mac Pro.

i, just wanted to report that I ran 3 1TB FW800 externals,daisy chained from an iMac that died when I installed 10.6 on it,but in 10.5 the FW bus had no trouble I could find. One time I added a FW Behringer 202? Audio interface at the end of the chain and it didn't work, leopard told me I had put too much on the Bus an it was shutting the Bus down. I removed said interface and reset the SMC and the FW Bus worked again until 10.6 when everything went bizarre,graphically speaking, I must update my stats to show all that has changed,only my excessive verbosity remains.