Anyway to disable firewire bus power? (Hooking up a 6 pin device to the 9 pin port)

Discussion in 'Mac Pro' started by musicguy7, Aug 9, 2011.

  1. musicguy7 macrumors member

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    Jun 21, 2011
    #1
    Hi,

    I am trying to hook up a Motu 828mk2 firewire soundcard to my 2010 Mac pro. The Motu has 6 pin firewire 400 ports while the mac pro has 9 pin firewire 600 ports. The Motu has its own ac adaptor for power. I don't want any chance of more power being sent to it via the firewire bus when I hook it up. Any way to disable firewire bus power through OSX?

    Also, there may be a chance I have nothing to worry about here, because the Motu is not suppose to be "bus powered" in the first place and requires the ac adaptor at all times, will the design of the device not "accept" any firewire bus power the mac pro will give it? or does it not work this way with firewire devices and they will get any firewire bus power available, just in some cases they require more through an adaptor?
     
  2. chrfr macrumors 603

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    #2
    It's not something to worry about. Firewire works interchangeably without having to do anything with power configurations. Devices that need power from the bus will use it, devices that don't, won't.
     
  3. musicguy7 thread starter macrumors member

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    #3

    Are you sure the setting of whether or not bus power will be drawn is dependent on the unique firewire peripheral device configuration? I am mainly reference this guy's past posts with hooking up his firewire soundcard that resulted in higher cpu temps and fans constantly being on:

    http://www.macosxaudio.com/forums/viewtopic.php?f=7&t=49264

    His situation seems to be the same as mine with bus power being sent even though an ac adaptor is being used.
     
  4. gr8tfly macrumors 603

    gr8tfly

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    #4
    As I posted in your other thread (hint hint), if the device doesn't need it, it doesn't use any power from the FW port.

    Both 9 pin and 6 pin FW supply power. Only the 4-pin configuration is powerless.

    Even if the device is bus powered, the CPU won't be affected. I suspect the poster you're linking to is seeing higher CPU temps due to whatever processes are running with the device connected.
     
  5. musicguy7 thread starter macrumors member

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    Jun 21, 2011
    #5
    Ok, yeah sorry probably shouldn't have double posted.

    So you're saying there is no way that other guy actually wasn't getting bus power when he was using the adaptor to his device as well?
     
  6. goMac macrumors 603

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    #6
    This is not something to worry about. Firewire 800 will work identically to Firewire 400 with a 6 pin device.

    In other words, if your device worked just fine with a Firewire 400 port, there will be no issues with an 800 port. I don't even think the power levels changed between them anyway.

    If the vendor didn't take into account power coming off of a Firewire 400 port... I would put it back in the box and send it back. Any reputable vendor would have taken care of that.
     
  7. derbothaus macrumors 601

    derbothaus

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    Jul 17, 2010
    #7
    Just a little addition. You actually may want to use the bus power on your interface. People spend lots of money for audio power conditioning to reduce noise and signal loss and I used to have an Ultra-lite MK3. It's power brick was not something I would call clean or hi-end.
    Sound-wise FW bus is generally cleaner power. Of course all this stuff is in the "maybe bull***" category.
    Motu uses a proprietary FW Audio driver. How much it takes away from the core driver I do not know but they did help Apple with it's inception.
     
  8. chrfr macrumors 603

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    #8
    It simply doesn't matter.
     
  9. ExnomenDei macrumors regular

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    #9
    Here's a creative, albeit unnecessary solution: A firewire-800 to 4-pin cable and then a 4-pin to 6-pin cable. But as other posters have said - stop worrying about it, and if you're really worried, unplug the AC adaptor unless you really need it (for phantom or something - though my Firestudio does it over FW).
     
  10. ActionableMango macrumors 604

    ActionableMango

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    Sep 21, 2010
    #10
    I have a hard time believing that an external device using firewire would heat up the CPU due to using firewire bus power. As gr8tfly mentioned, IF it's heating up the CPU, it's probably due to the related software processes putting demand on the CPU.

    I'd say before trying any mods at least hook it up and run it as intended by the manufacturer first. You may not experience any problem at all. Other guy may be in a hot room or have other problems.
     
  11. derbothaus macrumors 601

    derbothaus

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    #11
    The core audio driver in Macbook Pro's (at least) used to heat up mine by 10-15ºC. Now this was not the power but the communication. It is a known issue with Apples core audio driver. It became so irritating I bought the Motu because of the proprietary FW driver. It helped lower temps to 5ºC over idle. I have since avoided all audio gear that just uses Apples driver. I got rid of the Motu because the sound quality was weak. The cheapo interfaces like presonus use the generic core audio driver. Anything "plug and play".
     
  12. getz76, Aug 10, 2011
    Last edited: Aug 10, 2011

    getz76 macrumors 6502a

    getz76

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    #12
    External power is preferable to internal power supplies because you can remove RF and heat interference from your casing. The quality of the external supply can vary, though. A lot of units include internal power supplies because people still deem the wall-warts as "cheap", even though they are technically a better design. The high-end units that do use built-in supplies tend to have overbuilt shielding.

    Manufacturers still need to provide their own drivers for CoreAudio. The native driver isn't good for much. MOTU is considered to have some of the better drivers available. You will see any device with multi-channel audio will have CoreAudio drivers (Avid, Focusrite, Apogee, etc.).

    Regarding sound quality in general, there are a couple of considerations. First, you are only as good as the weakest link in your signal chain. Second, the quality of an interface is almost always determined by the quality of its ADC and DAC. Generally, you have really, really, really cheapy chips (iPod, lots of cheap USB units like iMics), you have the consumer/prosumer (Avid/Digidesign, MOTU, Focusrite) and then you have the stuff that is pricey (Apogee at the low end and stuff like Weiss at the higher end).

    That consumer/prosumer range can vary in huge amounts in cost, but generally there negligible difference in the actual quality. You can find some gems on the analog side of things as far as mics and preamps go, but the conversion side is a big blur of mediocrity. That said, the mediocrity is fine for most uses, even on the professional side of things.

    Back to the first point; with everyone listening through those awful iPod/iPhone earbuds and the awful DAC in iPod/iPhones, none of it really matters anymore.

    That's all just personal experience. Lots of cash spent. YMMV.
     
  13. TuffLuffJimmy macrumors G3

    TuffLuffJimmy

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    #13
    What the hell is Firewire 600?
     
  14. getz76 macrumors 6502a

    getz76

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    #14
  15. derbothaus macrumors 601

    derbothaus

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    #15
    I had heard quite the opposite from SonicStudio regarding power supply preferences. Either get a great conditioner or skip it (don't use the included ones). Anyway, I stopped worrying about DA/AD after getting my Metric Halo ULN-2 +DSP. Game is over. I just make music now. I tried every major brand and was disappointed up until that purchase. I actually preferred my Tascam 4-track portastudio to 90% of the "Digital" offerings.
     
  16. getz76, Aug 10, 2011
    Last edited: Aug 10, 2011

    getz76 macrumors 6502a

    getz76

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    #16
    A large majority of the "conditioners" are just power strips with a bunch of LEDs. Clean power and UPS is actually your best bet. Monster and Furman have made a bunch of money suckering people on this crap for about 20 years.

    Basic electrical engineering tells you to keep your processing as shielded as possible. External is technically "better" in a perfect world. You see this in some critical applications, especially in the medical field.

    The problem is that most manufacturers use wall-warts for two reasons; lower regulatory hassles for testing RF and compliance and because they are available on the cheap. The cheap ones are crap. The problem is plenty of the internal power supplies in cheaper units are also crap.

    The ULN-2 is a lovely unit. The Windows ASIO drivers are actually better than the CoreAudio drivers, too. Plenty of folks running at 32 samples at 96kHz in Windows and maintaining stability, whereas at 32 samples in OS X some people have issues and interrupts.

    There is a lot of crap out there, but I have learned to keep my head level and realize what is necessary for the end product. I see a lot of guys buying a Neumann and then throwing a Behringer preamp behind it while using a $5 mic cable into a $99 interface in an untreated room for their "hip hop studio".
     
  17. derbothaus macrumors 601

    derbothaus

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    #17
    Good thoughts Getz. Thanks. lol on the behringer dudes but really, it is hard to digest all the info out there if you really don't care about engineering. Most everyone I know is still tape based in their studios. The change for me has been hard. But the immediacy and convenience of digital is awesome. You just have to watch what is in your line way more than I ever had to with tape.
     
  18. getz76 macrumors 6502a

    getz76

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    #18
    Funny how we lowered our noise levels by going to a very unforgiving but clean digital and now we are spending thousands on plug-ins to add back that noise. The few spots here that still have tape are using it more for a hook than an actual tool. They are isolating everything and then just dumping it into Pro Tools and editing the crap out of it. Kinda defeats the purpose.

    I wish I was joking regarding the "BEATZ + JAMZ!" studios; hit NYC craigslist and you see "studio" time for $15/hour.
     
  19. musicguy7 thread starter macrumors member

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    Jun 21, 2011
    #19
    Alright, so I tested it out, and it seems normal.

    What do you guys know about hotplugging firewire interfaces? The motu has its own power, so is it ok to turn on the mac pro, then turn on the interface? that would be hotplugging no? Is it better to do it the other way around? motu first that is, then mac pro.

    BTW I am regretting getting the motu right now, dunno if it's just me, but it sounds real muffled and cloudy. Still can't imagine paying for a metric halo or apogee tho for almost the price of a mac pro right now...
     
  20. goMac macrumors 603

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    #20
    All Firewire devices are fully hotplugable in any order.
     
  21. derbothaus macrumors 601

    derbothaus

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    #21
    With the slight issue of needing to "jump start" certain FW configurations. My 2008 MBP needs this as does my 2010 Mac Pro. Apple changed the device power at one point and you may need to plug in the adapter briefly to get current going. You can then unplug it and run off the FW bus.
     
  22. getz76 macrumors 6502a

    getz76

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    #22
    I have an 828mk2 in a rehearsal space. Read what I wrote above regarding ranges of gear.

    If you cannot afford the Apogee or similar, the MOTU is likely not the weak link in your chain. What are you monitoring through? What are you comparing it to? Is your room treated? Are you listening to raw tracks or mixed and mastered?
     
  23. derbothaus macrumors 601

    derbothaus

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    #23
    I don't know dude. I absolutely hated my MOTU gear. I stopped making music and was a bit depressed by the results. A presonus firebox had better DA to my ears (the pres on both were pretty terrible). I think the "iMic" was better. But if you are cash strapped an Apogee Duet is supposed to be pretty great for around 500.00. That would be in the "affordable" range imo. You may even find a version 1 for less used and they are supposed to still be better than the version 2 USB one according to gearslutz buddies.
     
  24. getz76 macrumors 6502a

    getz76

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    #24
    I never question anyone's subjective taste. Use what you like. ;)

    Your taste does go against consensus, though; MOTU gear is generally reviewed as solid, adequate gear and a bit of a bargain in the price range. Not saying it is right for everybody... and some people hate CueMix.

    All I want out of a built-in preamp is it to not be noisy. That's all I expect.

    My current mobile rig has a MOTU UltraLite mk2. I find it adequate. Most of the stuff I end up recording with it is actually going through an RME ADI-2 and a pair of Summit Audio 2BA-221s, so I am usually not using the converters or the preamps.

    Gearslutz is interesting, but that place is also full of group-think. A couple of key members buy one thing, and everyone else jumps on it for about 6 months until the next toy comes around. I still wonder if some of the heavies over there are getting kickbacks from some of the mic-modifiers on the net...
     
  25. derbothaus macrumors 601

    derbothaus

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    #25
    Things can get weird. I don't go there very much unless I need general consensus. Usually to reinforce the views I already hold (It's the net you know)
    Sound is personal and completely subjective. I did not want to make anyone feel they need to justify what they use. It all works and in the right hands, even the Voice Memo's app on the iPhone could get you OK results. A cheap Mbox PT9 setup could get you released. It's a new world.

    I thought it important as my opinion mirrored the OP's in wondering why the sound was not "there".
     

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