Fosi PH-05 Headphone Distribution Amplifier

[amirm]

This is a review and measurements of the Fosi Audio PH-05 five (5) channel analog headphone distribution amplifier. It was kindly sent to me by a member and costs US $49.

The package is extraordinarily nice given the price. Controls feel nice and having five outputs at once each with their own volume control is more than one could ask for. A tiny power supply powers the unit in the back. Note that I have tilted it up. Normally sits flat.

So it is clear what the device does, you feed it one analog stereo input using 3.5 mm jack, and then have five outputs of the same signal, each with their own volume trim. And then a master volume control.

EDIT: I mistyped the model number as FH05 instead of PH05. Sorry about that.

Fosi Audio PH05 Headphone Distribution Amplifier Measurements
To have a realistic situation, I opted to drive the FH05 using a high-performance headphone amplifier, the Topping A90:

I then fed the output of A90 to FH05. Trying to get 4 volts out caused clipping so I backed off on the input to PH05 and adjusted the output to avoid clipping:

So we loose good bit of performance. Let's measure to see how much power we have at 300 and 32 ohm:

Sadly we don't have much power and what we have is in dongle adapter category, albeit a more powerful one.

Conclusions
Fosi nails the functionality and look/feel of the unit with PH05. Hard to imagine you can get anything close to that for $49. Alas, compromises had to be made to have not one, but five stereo headphone amplifiers here. Both in power and noise+distortion. I love to see Fosi build a higher end one with more powerful and lower distortion amplifiers, at least for one channel.

I can't recommend the Fosi Audio PH05 from overall performance point of view. That said, I could not produce a better product and sell it so cheap!
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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

 

[amirm]

Reserved for @AdamG to kindly post the specs.

Manufacturer Specifications:

 

[shuppatsu]

What in the world is this for?

 

[amirm]

What in the world is this for?

Multiple people previewing the same content at once using headphones.

 

[Doodski]

What in the world is this for?

Like for example 2 or more people playing a PC game and they all can hear it through multiple headphones with each person having their own volume control.

 

[Rja4000]

Thanks for the review.

Is that passive or active ?
I suppose active if you have a power supply.
So the power is limited by it.
Would it accept a bigger PS ?
Would that allow more power ?

 

[phoenixdogfan]

Like for example 2 or more people playing a PC game and they all can hear it through multiple headphones with each person having their own volume control.

So they can have absolute control of their environment while they LARP at each other?

 

[JeremyFife]

A bit niche: if you need this functionality then it's fine, although I confess I know nothing about alternatives.
Otherwise, well you don't need it...

 

[amirm]

Is that passive or active ?

Active. I expected it to be passive but it is not. Having 10 channels audio and sell for $50 is a major limitation. The power supply is also quite small and likely low power.

 

[amirm]

Would it accept a bigger PS ?
Would that allow more power ?

I doubt it but even if it increases power, it may then overheat.

 

[restorer-john]

Active. I expected it to be passive but it is not. Having 10 channels audio and sell for $50 is a major limitation. The power supply is also quite small and likely low power.

It reminds me of the headphone distribution boxes we had back in the 1970s at school for audiobooks at the library. The headphones were hideous things that crushed our heads.

here's another type:

https://www.aliexpress.com/item/1005007125076042.html

 

[yo!]

Hello
The output power for high impedance headphones is really very weak.
But I wouldn't call 80 mW @32 Ohm poor, it's absolute sufficent for low impedance gear.

 

[solderdude]

@amirm can you measure the output resistance ?
Some designs like this use 1 amp internally and use passive volume controls on each output (thus varying output R depending on volume setting)
Could also be that this one has 5 buffers following each individual channel. Op-amps cost nearly nothing in bulk.

 

[Joemoonit]

I'd love to have one of these back in the days of my radio show, it was always a problem when we had more than one guest. Quality of course was not a problem, it was only for spoken words.

 

[ObjectiveSubjectivist]

I do not really see use case for such product.

 

[AndreaT]

As a device to compare headphones it might confuse the customer: the more efficient set with higher impedance will likely sound as it is, the least efficient with lower impedance will have audible added distortion, clipping and lower volume.

 

[Cbdb2]

What in the world is this for?

Recording studios where all the members of the band need headphones at the same time, probably not loud enough thou which is too bad, the standard way is to use the speaker outs of a power amp and individual pots. A lot more expensive but you can drive dozens of phones (depending on there impedance).

 

[Tatteredmidnight]

I have a few of these lying around.

I use the box as a stand for my light, other than that I no longer have a use for them. These are primarily targeted at the pro audio scene and used to be fairly common (may still be). I’d be happy to send one in for testing, didn’t think people would be interested previously.


Link:

Aphex Technology - Making Your World Sound Better

Aphex technology is used in a wide range of pro audio and prosumer applications for music, video, gaming and communications; and are licensed into a variety of audio, entertainment and communications products.

aphex.com

 

[VientoB]

Can anyone explain why you would want 5 headphones outputs with their own volume control? And a master volume control?

 

[Blumlein 88]

Can anyone explain why you would want 5 headphones outputs with their own volume control? And a master volume control?

Recording. Very common. Very useful. Each musician can hear the mix and each other.