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What does "Bus powered" mean for an audio interfaces sound quality?
Old 15th June 2016
  #1
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What does "Bus powered" mean for an audio interfaces sound quality?

I am torn between purchasing a Clarett 2 pre and a Zoom Tac-2R and would like the best sound quality possible so not sure which to get. Obviously the Clarett is more expensive but it has some "air" feature which doesn't really appeal to me so taking that away maybe the sound quality of these units is more or less the same?

I do notice that the Clarett is not bus powered and was wondering if this might affect the sound quality in some way?
Old 15th June 2016
  #2
Gear Nut
 
🎧 5 years
Bus power wont affect the sound... Most expensive interfaces use that now. But you are most likely overpaying for those units. Reminds me of when I wasted money on a roland quad-capture lol. too much money too little brains. you dont need gigabytes of audio data to be going through that cable. dont be stupid bruh.
Old 16th June 2016 | Show parent
  #3
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Quote:
Originally Posted by Mechacaseal ➑️
Bus power wont affect the sound... Most expensive interfaces use that now. But you are most likely overpaying for those units. Reminds me of when I wasted money on a roland quad-capture lol. too much money too little brains. you dont need gigabytes of audio data to be going through that cable. dont be stupid bruh.
That isn't true Mechacaseal. Looking at the range of thunderbolt interfaces, the clarett and the apollo twin (which are the two higher end thunderbolt interfaces) have separate power supplies and are not bus powered while the zoom, resident audio and scarlett (the three cheaper interfaces) are all bus-powered. I won't ask you why that is because it sounds like you are really unsure since you say that all higher end interfaces are bus-powered.
Old 16th June 2016
  #4
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🎧 5 years
Bus powered: first of all, less power to work with. USB provides 5 V and up to 900 mA. That's not too much at all. Non-bus powered devices usually work with 9 or 12 V. Means for bus powered devices, the electronic parts must be of different specifications. Same operation with less voltage and current. Think of OpAmps, converters, DSP and whatsoever.

Next, think of the power adapter that has to be *somewhere* in the chain. The one of your computer. Those are not (at all) known for "clean" power... meaning a lot of interspersal into the the circuit. Which is known to be a serious issue for audio quality.


Apart from the bus powered / non bus powered stuff. I think Zoom products and Clarett interface are just a different league. Imho, Zoom is "professional consumer" products, while Focusrite is a company with a respectable history in high-end audio, bringing their experience to low/mid prize market.

Still, this is not meant to be any judgement about usability of these two products. It depends on the purpose. You want to record podcasts? Zoom is perfect quality for that. You want to record and mix audio (where a lot of channels - and their respective quality - are added up)? Get the best quality you can afford (keeping the entire signal chain in mind).
Old 16th June 2016 | Show parent
  #5
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Quote:
Originally Posted by livebox ➑️
Bus powered: first of all, less power to work with. USB provides 5 V and up to 900 mA. That's not too much at all. Non-bus powered devices usually work with 9 or 12 V. Means for bus powered devices, the electronic parts must be of different specifications. Same operation with less voltage and current. Think of OpAmps, converters, DSP and whatsoever.

Next, think of the power adapter that has to be *somewhere* in the chain. The one of your computer. Those are not (at all) known for "clean" power... meaning a lot of interspersal into the the circuit. Which is known to be a serious issue for audio quality.


Apart from the bus powered / non bus powered stuff. I think Zoom products and Clarett interface are just a different league. Imho, Zoom is "professional consumer" products, while Focusrite is a company with a respectable history in high-end audio, bringing their experience to low/mid prize market.

Still, this is not meant to be any judgement about usability of these two products. It depends on the purpose. You want to record podcasts? Zoom is perfect quality for that. You want to record and mix audio (where a lot of channels - and their respective quality - are added up)? Get the best quality you can afford (keeping the entire signal chain in mind).
they got past that clean bus power problem a loooong time ago. maybe some cheap usb mics still have that problem tho.

Quote:
Originally Posted by attaboy_jhb ➑️
That isn't true Mechacaseal. Looking at the range of thunderbolt interfaces, the clarett and the apollo twin (which are the two higher end thunderbolt interfaces) have separate power supplies and are not bus powered while the zoom, resident audio and scarlett (the three cheaper interfaces) are all bus-powered. I won't ask you why that is because it sounds like you are really unsure since you say that all higher end interfaces are bus-powered.
The higher end one you mention has way more preamps to power so yes it may need more power than bus can offer. there are some pretty expensive interfaces that have less inputs and outputs that are completely bus powered. you are paying a TON for some midi inputs, overly fast digital connection to pc, etc. i hope you actually know and have a reason as to why youre paying that much cause 24 bit at 192 is just to sell to stupid people since that its overkill.

https://www.amazon.com/Steinberg-UR2...berg+ur22+mkii

we can see this interface does both probably cause if youre using a laptop or ipad (lol) you may want to use the 5v power adapter. yes thats right 5v... not 12v... MORE IS NOT BETTER. its overkill most the time.
Old 16th June 2016 | Show parent
  #6
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Quote:
Originally Posted by livebox ➑️
Bus powered: first of all, less power to work with. USB provides 5 V and up to 900 mA. That's not too much at all. Non-bus powered devices usually work with 9 or 12 V. Means for bus powered devices, the electronic parts must be of different specifications. Same operation with less voltage and current. Think of OpAmps, converters, DSP and whatsoever.
when you say "different" specifications, could that mean "better" specifications? I may be wrong here but if the twin and clarett are using 9-12V it is because their performance would be affected if they were built using parts that could be run on 5v?
Old 16th June 2016
  #7
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I don't know if some of the bus powered interfaces use the advantages of USB3 or thunderbolt, but imo USB 2.0 bus powered interfaces are limitated. It's simply not enough juice for phantom power and good headphone amps. The Focusrite Forte for example doesn't offer phantom power when bus powered and lowers the output of the headphone amp when bus powered (that is a good compromise imo).
Old 16th June 2016
  #8
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🎧 10 years
Just look at the Audient interfaces...they had to use different op-amps on the 14 because there isn't enough juice through bus power for them otherwise.

I've noticed a difference mainly in mic pres on bus power, but I'd still rather use a wal wart to power my stuff.
Old 16th June 2016
  #9
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Absolutely nothing. Though you may experience ground noise with some devices .
Old 16th June 2016 | Show parent
  #10
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🎧 5 years
Quote:
Originally Posted by DirkP ➑️
It's simply not enough juice for phantom power and good headphone amps.
brace yourselves for the millions of recalls. all this time my 4 usb interfaces that can power a sm7b, condensers, and blow out my studio speakers have been faking it.
Old 16th June 2016 | Show parent
  #11
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Quote:
Originally Posted by Mechacaseal ➑️
brace yourselves for the millions of recalls. all this time my 4 usb interfaces that can power a sm7b, condensers, and blow out my studio speakers have been faking it.
Yep - if you listen back to all those recordings you made you will notice - YOU CANT HEAR THE VOCALS IN ANY OF THEM !!!!

No problem buddy - just pick yourself up again, dust yourself off - and keep climbing that mountian
Old 16th June 2016 | Show parent
  #12
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🎧 10 years
Quote:
Originally Posted by Mechacaseal ➑️
brace yourselves for the millions of recalls. all this time my 4 usb interfaces that can power a sm7b, condensers, and blow out my studio speakers have been faking it.
If you design a unit for bus power it's going to sound the same on bus power or not. If a unit is designed for maximum performance that cannot be powered without an external supply because of current draw, that's a totally different thing.
Old 16th June 2016 | Show parent
  #13
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Quote:
Originally Posted by attaboy_jhb ➑️
when you say "different" specifications, could that mean "better" specifications? I may be wrong here but if the twin and clarett are using 9-12V it is because their performance would be affected if they were built using parts that could be run on 5v?
Lower voltage = lower headroom.

Not sure what Apogee is doing, but I'm told their buss powered interface (Duet) sounds great.

I only have experience w/ the Quartet.

Anecdotally, the only interfaces I've really disliked the sound of have been buss powered. But I've only used a handful of these smaller interfaces.
Old 16th June 2016 | Show parent
  #14
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Quote:
Originally Posted by Mechacaseal ➑️
LOL

I don't know what that video means, but maybe I'm not being clear.

I'll try again...

If a unit is DESIGNED to work within the constraints of buss power, it won't matter if you feed it with an external supply that can supply more. It should be no different.

Generally, high switching rates that you need to have high resolution also require more power to pull off. So in GENERAL you won't find much high end stuff that runs off buss power.
Old 16th June 2016 | Show parent
  #15
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Quote:
Originally Posted by Ron Vogel ➑️
I don't know what that video means, but maybe I'm not being clear.

I'll try again...

If a unit is DESIGNED to work within the constraints of buss power, it won't matter if you feed it with an external supply that can supply more. It should be no different.

Generally, high switching rates that you need to have high resolution also require more power to pull off. So in GENERAL you won't find much high end stuff that runs off buss power.
that is what I figured so I don't know why mekakaseal said that high end stuff is bus powered?

Are there any high-end interfaces that are bus powered?
Old 16th June 2016 | Show parent
  #16
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Quote:
Originally Posted by attaboy_jhb ➑️
that is what I figured so I don't know why mekakaseal said that high end stuff is bus powered?

Are there any high-end interfaces that are bus powered?
Depends on your definition of high-end, but aside from the aforementioned Duet, the Sound Devices USBPre 2 is definitely a professional grade device.
Old 16th June 2016 | Show parent
  #17
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Quote:
Originally Posted by Mechacaseal ➑️
brace yourselves for the millions of recalls. all this time my 4 usb interfaces that can power a sm7b, condensers, and blow out my studio speakers have been faking it.
I didn't doubt that you can make high quality recordings with a usb powered interface. BTW an sm7b is a dynamic mic that doesn't need to be powered:-)

I doubt that there is an usb powered interface that has a high quality headphone amp that has enough juice for 600 ohm headphones or a power hungry headphone like a K701 and can power 2 condenser mics at the same time. If you have a headphone that has a high output and less impedance it might not matter to you.

The engineers at Focusrite didn't decide just for fun to let the headphone amp have 6 db less and to not allow phantom power when bus powered.
Some engineers might be better than others and in case of the Forte that uses special software it might be even harder to work around the limitations.
But why having limitations if it isn't necessary.

I have 4 usb powered interfaces, some are very good but all are limited. If these limitations matter to you is a different case.
The SPL Crimson which needs to be powered with an external supply is much much better, esp. the headphone amps.

In short form: the low voltage that usb 1.0 and 2.0 deliver are a serious challenge for engineers.
Another advantage of interfaces with a power supply: they work flawlessly with ios devices.

But on the one hand the new camera connection kit solves that problem and on the other hand USB 3.0 and thunderbird delives enough juice, so we don't have this discussion anymore in the future:-)
Old 16th June 2016 | Show parent
  #18
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Quote:
Originally Posted by attaboy_jhb ➑️
that is what I figured so I don't know why mekakaseal said that high end stuff is bus powered?

Are there any high-end interfaces that are bus powered?
The Metric Halo 2882 is FW bus powered. And it's fairly dated now. High end is a matter of perspective, I suppose.

Converters don't need to be big current hogs. When you start getting into powering arrays of phantom mics, internal DSP, etc. then you can need more power than what a computer bus can provide.

I think the OP seems to think that somehow bus power is underpowered compared to external power on a unit that could be powered by either. It has more to do with the design and power requirements of the unit. If a unit is designed to be powered by what a typical USB, FW, TBOLT bus can provide, then using an external power supply shouldn't change anything - there will be some sort of regulation circuit in there. It will operate within spec with either power source if it's been competently designed. You can do a lot with 5-30v and 2.5-20W of a USB or FW port.

But a unit that is designed for greater draw than what a bus can provide - well, possible that such a unit can use higher voltages and increased power to its advantage increase headroom, not sag, etc.
Old 17th June 2016 | Show parent
  #19
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🎧 10 years
Quote:
Originally Posted by Mechacaseal ➑️
brace yourselves for the millions of recalls. all this time my 4 usb interfaces that can power a sm7b, condensers, and blow out my studio speakers have been faking it.
He said headphone amp. Your speakers are fed line level from the interface and have their own amp (or an external amp).

You're not understanding the issue.
Old 19th June 2016 | Show parent
  #20
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Quote:
Originally Posted by travisbrown ➑️
Converters don't need to be big current hogs. When you start getting into powering arrays of phantom mics, internal DSP, etc. then you can need more power than what a computer bus can provide.

I think the OP seems to think that somehow bus power is underpowered compared to external power on a unit that could be powered by either.
I was just under the impression that higher end components and higher end audio interfaces would not be able to run solely on bus power. Another way to ask the question is:

Why does the clarett 2 have a power supply while the scarelett or zoom tac2R or audient run off bus power? Is it because the clarett 2 demands higher power supply and is this in anyway related to the actual sound quality of the clarett. If the answer is no, then why would Focusrite not make the clarett bus powered as well?
Old 20th June 2016 | Show parent
  #21
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Quote:
Originally Posted by attaboy_jhb ➑️
I was just under the impression that higher end components and higher end audio interfaces would not be able to run solely on bus power. Another way to ask the question is:

Why does the clarett 2 have a power supply while the scarelett or zoom tac2R or audient run off bus power? Is it because the clarett 2 demands higher power supply and is this in anyway related to the actual sound quality of the clarett. If the answer is no, then why would Focusrite not make the clarett bus powered as well?
I would guess because the Clarett comes in 2, 4 and 8 preamp channel configurations and they would have shared topology across the various models. The Clarett looks to supply full 48v for all preamps, so I would suspect that might be a bit too much draw for bus power and operate within specs with the 8 channel version. So they use a PSU for all versions.

I think you are worrying about it too much. IF the device operates within spec with bus power, everything is A-OK. High grade components don't neccessarily equal more draw. In some cases designs with lower grade components could be less efficient and require more power to operate within spec.
Old 21st June 2016 | Show parent
  #22
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Quote:
Originally Posted by travisbrown ➑️
I would guess because the Clarett comes in 2, 4 and 8 preamp channel configurations and they would have shared topology across the various models. The Clarett looks to supply full 48v for all preamps, so I would suspect that might be a bit too much draw for bus power and operate within specs with the 8 channel version. So they use a PSU for all versions.

I think you are worrying about it too much. IF the device operates within spec with bus power, everything is A-OK. High grade components don't neccessarily equal more draw. In some cases designs with lower grade components could be less efficient and require more power to operate within spec.
ok but you said that you have 4 bus powered interfaces and they are limited in your other post. Why is that then?
Old 21st June 2016 | Show parent
  #23
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Quote:
Originally Posted by attaboy_jhb ➑️
ok but you said that you have 4 bus powered interfaces and they are limited in your other post. Why is that then?
Not sure I wrote that. I have a few bus powered interfaces, but don't think I spoke of them.

They are limited in the power they can provide to dependent devices like full-power phantom mics, or onboard DSP.
Old 22nd June 2016 | Show parent
  #24
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🎧 10 years
Quote:
Originally Posted by attaboy_jhb ➑️
ok but you said that you have 4 bus powered interfaces and they are limited in your other post. Why is that then?
One of the biggest limitations of bus powered interfaces is power supplies TO them.

If you have a mains powered interface it draws very little current from the USB itself. Which is important if you're also running iloks, USB keys, drives or midi controllers.
Old 22nd June 2016 | Show parent
  #25
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Quote:
Originally Posted by travisbrown ➑️
Not sure I wrote that. I have a few bus powered interfaces, but don't think I spoke of them.

They are limited in the power they can provide to dependent devices like full-power phantom mics, or onboard DSP.
sorry it was the guy above you, he says

I have 4 usb powered interfaces, some are very good but all are limited. If these limitations matter to you is a different case.
Old 22nd June 2016 | Show parent
  #26
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Quote:
Originally Posted by attaboy_jhb ➑️
sorry it was the guy above you, he says

I have 4 usb powered interfaces, some are very good but all are limited. If these limitations matter to you is a different case.
as he states in the post

- power of headphone amp
- ability to supply phantom power (also some interfaces will appear to be supplying power but it won't actually be the full 48v - some mics are fussier than others).
- plus the issues with power per USB device I mentioned.

That's 3 fairly important things to consider. At least the OPTION of buss powering or mains powering is good.
Old 22nd June 2016 | Show parent
  #27
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if you have a 10 port HUB and you want 0.5 Amp from each port, that's a total of 5 Volts @ 5 Amps.
5 X 5 = 25. so that's a 25 Watt PSU you'll need just for the HUB. if that's a PSU with a max 25 watt rating
then that will be running HOT!!. so then a PSU with double that rating is better to make it run cooler.

it's more about understanding and checking the power requirements of the device and IF the HUB or the
power management in the computer is straining to deliver it. so if you have a bus powered device, connected
to a hUB which is feeding other devices too, you want to make sure it has a good PSU & maybe that you only
draw half its max rating.

Audio interfaces with their own power input is generally best to use, because you don't have all the above to get right.
given that, you need to make sure the HUB can deliver the needed power for the unit, when you have a bus powered interface.
Old 22nd June 2016 | Show parent
  #28
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Quote:
Originally Posted by psycho_monkey ➑️
as he states in the post

- power of headphone amp
- ability to supply phantom power (also some interfaces will appear to be supplying power but it won't actually be the full 48v - some mics are fussier than others).
- plus the issues with power per USB device I mentioned.

That's 3 fairly important things to consider. At least the OPTION of buss powering or mains powering is good.
yeah I think I am going to go for the focusrite clarett after reading this actually... I have a Neve Portico 5012 that will be powering my microphones so not fussy about the preamps but those three issues above seem enough to make me skip having a bus powered interface.

I also wonder why the apollo twin is not bus powered since it is only two channels? I guess they couldn't have built a good quality 2 channel interface like that solely on bus power? else surely they would have?
Old 22nd June 2016 | Show parent
  #29
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🎧 10 years
Quote:
Originally Posted by attaboy_jhb ➑️
yeah I think I am going to go for the focusrite clarett after reading this actually... I have a Neve Portico 5012 that will be powering my microphones so not fussy about the preamps but those three issues above seem enough to make me skip having a bus powered interface.

I also wonder why the apollo twin is not bus powered since it is only two channels? I guess they couldn't have built a good quality 2 channel interface like that solely on bus power? else surely they would have?
The Twin has the DSP built in - which is a prime candidate for needing more power!

Also it's got some serious engineering - relay switching, the flexible rotary encoder etc - going on under the hood. I am in no way surprised it's not buss powered.

Plus it does 10 in, 4 out with ADAT expansion of course.
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