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3 Channel Headphone Amps & Virtual Grounds
3 Channel Headphone Amps & Virtual Grounds
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Old 14th May 2011, 05:22 AM   #1
RocketScientist is offline RocketScientist  United States
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Default 3 Channel Headphone Amps & Virtual Grounds

For anyone interested in such things, 3 channel headphones amps (like the AMB M3, Mini3, B22, Tangent Pimeta, etc.) were something of a mystery to me. After testing a few, I looked more into the claimed benefits, history behind them, etc. and ended up writing an article:

3 Channel Headphone Amps & Virtual Grounds

If I'm missing something, or got something wrong, please let me know?

Click the image to open in full size.
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Old 14th May 2011, 06:06 AM   #2
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I find the concept a little confusing. If I use this as a pre to drive a power amp, wont the amps ground ground the ground channel and cause a meltdown?
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Old 14th May 2011, 06:26 AM   #3
RocketScientist is offline RocketScientist  United States
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These amps are only meant for driving headphones, which electrically, are isolated from the world. So it doesn't matter if the output ground is sitting at half the power supply voltage. In some of these amps (including the Mini3) the input "ground" is also sitting at half the battery voltage along with the entire metal chassis for that matter. But, again, it usually doesn't matter as it's either running from its isolated battery, or an isolated power supply.

But yes, if you were to power one of these amps from a power supply that had a grounded output, and connect the amp to pretty much anything else that was grounded, the virtual ground "channel" in the amp would be seriously unhappy and might meltdown as you suggest.
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Last edited by RocketScientist; 14th May 2011 at 06:30 AM.
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Old 14th May 2011, 06:39 AM   #4
Luke is offline Luke  New Zealand
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yep I know, but I put a couple of rca out on my M3 and I thought about trying it as a pre. I had doubts about it working. Now that i think about it, I can use signal and the ground of the amp without using the virtual ground.
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Old 14th May 2011, 02:07 PM   #5
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This was a very useful writing! I learned a lot from it.
Thank You RocketScientist.
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Old 14th May 2011, 06:25 PM   #6
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You're welcome Earfanatic.
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Old 14th May 2011, 11:52 PM   #7
linuxworks is offline linuxworks  United States
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some more discussion on both 'sides' here, for example: B22/Active Ground Query - Head-Fi.org Community

lets just say that a lot of people think that 3ch works; and yet, quite a few do question that topology. I don't think its been settled enough to convince the doubters; but I would not want to read one person's view and conclude that this represents everyone's views.
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Old 14th May 2011, 11:54 PM   #8
linuxworks is offline linuxworks  United States
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Quote:
Originally Posted by Luke View Post
yep I know, but I put a couple of rca out on my M3 and I thought about trying it as a pre. I had doubts about it working. Now that i think about it, I can use signal and the ground of the amp without using the virtual ground.
you can do both. I have a 3ch b22 that I use for both line-out and for phones-out. on phones-out, I get gnd from the 3rd gnd buffer or channel. on line out, though, I use input gnd as my output gnd. there's no 'load' to have to worry about 'driving' when you are a preamp; its only for loads like phones that you'd care about having a 3rd channel.

so, its not either/or. you pick the right thing for the right target device you are going to drive.
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Old 15th May 2011, 12:05 AM   #9
RocketScientist is offline RocketScientist  United States
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Quote:
Originally Posted by linuxworks View Post
lets just say that a lot of people think that 3ch works; and yet, quite a few do question that topology. I don't think its been settled enough to convince the doubters; but I would not want to read one person's view and conclude that this represents everyone's views.
My position is objective, while much of what you're talking about subjective.

I'll gladly discuss any supposed factual, objective, and measurable advantages to 3 channel headphone amps. Even in the thread you reference, I'm not aware of any. Most of what's in that thread is either subjective (i.e. "sonic bricks"), misleading, or just plain wrong.
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Old 15th May 2011, 12:16 AM   #10
linuxworks is offline linuxworks  United States
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you may want to avoid such absolute terms as 'just plain wrong'.

unless someone crowned you the ultimate judge of this stuff, I suggest you present your views as just that, views.
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