Fireface 400 - Anybody getting bus power on an Intel Mac?

kechambe · Post by **kechambe** » Thu Aug 10, 2006 12:32 am

The problem I have is:
The Fireface 400 can't power up off the bus. If I power it up of the power supply and then remove it, it will continue to run with only bus power. So it's only bus powered startup that fails.

This is what I tried:
I hooked my Fireface 400 to my Powerbook 17 and had no problems. So my Macbook Pro 17 does not work, but the Powerbook 17 does.

Research:
I went searching online for solutions and found that the Powerbook will provide 15 W.

Per RME the Fireface 400 needs:
• Typical power consumption: 13 Watts
• Current at 12 Volt operating voltage: 910 mA (11 Watts)

So clearly the Powerbook 17 is within spec.

The Macbook Pro 17 provides slightly less if you are only using a single port, which I am. (No Firewire 800.) Apple documents this online:
http://developer.apple.com/documentatio ... ation.html

"Both of the FireWire connectors provide unregulated 12 V power, with a maximum combined load of 1.5 A. Developers should design to use 14 W sustained power, or less. One port may provide up to 14 W if no power is drawn from the other port, or both ports combined may provide up to a total of 14 W, such as 7 W from each port, simultaneously."

So it looks like the Macbook Pro 17 provides more then what the Fireface 400 needs. (14 W vs 13/11 W and 1.5A vs 910mA.) But this is where it gets interesting:

From the same Apple doc:
"Note: The 17-inch MacBook Pro includes fast-acting over-current protection, hence, FireWire devices that consume cable power must comply with IEEE 1394 section 4.2.2.7 regarding maximum inrush energy."

So I'm wondering if RME dropped the ball on this? The Fireface ships with a special sheet telling you about the problems with frying Firewire devices. So they must have been aware of 4.2.2.7 -- I hope. Eitherway -- I am going to insist they get this sorted out. I don't consider any Macbook to be an obscure platform.

I have contacted Synthax but they don't know off hand. And their main support guy, George, is on vacation.

Soooo -- if you got it working, let me know!

Cheers,
Keith

Also -- The Macbook Pro 15 apparently can only put out 7 Watts total. So maybe it can't even power it once it's running. I'm assuming the Macbook will be the same but that's just a guess. Couldn't find any data on it.

Surreal · Post by **Surreal** » Thu Aug 10, 2006 2:50 am

i think that there is a good chance that it is an issue with the computer, as i have the MBP 17" as well and there are slight issues with USB ports. (only one works flawlessly)

i think you might want to try a firewire 9 to 6 pin cable if you know someone with it and see if the 800 port might supply enough power.

i HOPE it is an issue with RME, cause they might fix it if it is. PLEASE post whatever happens as i am seriously considering supplementing my FF 800 with the 400 since they share a driver. i need something more portable than the 800 and i was looking at interfaces with much less IO for much less money, but the two interfaces sharing a driver sounds like it would make for more stability when used together (6 preamps YAY)

how is the interface treating you in regards to sound? any qualms? anything ridiculously great?

John Sweet · Post by **John Sweet** » Thu Aug 10, 2006 12:14 pm

Have you tried the RME newsgroup? They're supposed to be helpful.

Are you still inside 30 days from the purchase? Might want to swap for something inside the MBP specs. Maybe Echo or MOTU?

This makes me nervous, as I was planning to get a 17 this month.