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Fosi Audio HD-A1 Budget Amplifier Review

amirm

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#1
This is a review and detailed measurements of the Fosi Audio HD-A1 amplifier. It costs US $200 on Amazon including Prime shipping. It was kindly sent to me for testing by member @IowAudio. He has a review of it on youtube.

The front is not bad for a budget product:

Fosi Audio HD-A1 Hi-fi Power Amplifier Audio Review.jpg


The font could use some help but you don't listen to that. Nice to have a volume control as many budget amps don't have one.

The back panel connectors are unusually high quality:

Fosi Audio HD-A1 Hi-fi Power Amplifier Back Panel Input Binding Posts Audio Review.jpg


Oddly the power switch is on the left (right above).

There are no safety or regulatory certifications which is always a concern for mains operated product.

In use the unit was quite robust, never shutting down or getting overly warm.

Company advertises that the topology is similar to Marantz's HDAM amplifier stage. Whether that is the case or not, I have not tried to investigate:

1595267606726.png


The amplifier is Class AB and uses a toroidal transformer which makes it quite heavy and sturdy for its size.

Amplifier Audio Measurements
As usual we test for noise and distortion by asking the amplifier to produce 5 watts into 4 ohm load using a 1 kHz signal:

Fosi Audio HD-A1 Hi-fi Power Amplifier Audio Measurements.png


This is not good. We have tons of power supply related spikes (left of our 1 kHz tone) and harmonic distortion after our tone. I suspect this is a low feedback design and as such, is not very linear. No wonder then that the ranking amount all the amplifiers tested is almost at the bottom:

Best stereo budget amplifier review 2020.png


There is some talk about it being tube like so maybe that is the excuse for poor performance.

Noise performance is not great either:
Fosi Audio HD-A1 Hi-fi Power Amplifier SNR Measurements.png


Frequency response and crosstalk on the other hand are very good:

Fosi Audio HD-A1 Hi-fi Power Amplifier Frequency Response Audio Measurements.png


Fosi Audio HD-A1 Hi-fi Power Amplifier Crosstalk Audio Measurements.png


But our 32-tone signal resembling "music" is not:

Fosi Audio HD-A1 Hi-fi Power Amplifier Multitone Audio Measurements.png


Power into 4 ohm load does not meet spec:

Fosi Audio HD-A1 Hi-fi Power Amplifier Power into 4 ohm Audio Measurements.png


It gets closer though if we allow more distortion:

Fosi Audio HD-A1 Hi-fi Power Amplifier Max and Burst Power into 4 ohm Audio Measurements.png


Naturally power drops with 8 ohm load:

Fosi Audio HD-A1 Hi-fi Power Amplifier Power into 8 ohm Audio Measurements.png


Conclusions
The Fosi HD-A1 amplifier promises more from its looks and weight than it delivers in transparency. Then again there is some pretension of tube line sound and such so maybe this is intentional. The high distortion and noise don't do much for me so it is not something I can recommend. But I didn't want to give it the lowest score because I don't know if there is anything better in this power range and price.

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As always, questions, comments, recommendations, etc. are welcome.

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amirm

amirm

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Thread Starter #2
By the way, the above is the 100th amplifier I have reviewed! Can you believe it? It seems it was just yesterday that I was happy to just be testing lightweight desktop products. I wanted to thank all the people who have sent these in for testing but my aching back doesn't allow it. :)
 

MZKM

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#3
But I didn't want to give it the lowest score because I don't know if there is anything better in this power range and price.
$80 more gets you a Denon S540 5.1 receiver, would be interesting to see how that compared to this 2ch analog amp.
 
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amirm

amirm

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Thread Starter #4
$80 more gets you a Denon S540 5.1 receiver, would be interesting to see how that compared to this 2ch analog amp.
AVRs are huge though so I don't see them being a proper replacement for these amplifiers where you want to stick a piece of furniture and have some music.
 

daftcombo

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#5
Hi Amir! Thanks for the review. I'm very happy to read reviews of budget amplifiers like that because I think a lot of us are still on the quest to a golden little amp.

Now that you have a lot of speakers at your disposal, will you consider doing a subjective listening of those amps?
 
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amirm

amirm

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Thread Starter #6
Now that you have a lot of speakers at your disposal, will you consider doing a subjective listening of those amps?
I was hoping to do that but I am getting so hammered to test gear that I just don't have the time at the moment. There are so many boxes in our entry way that no matter how fast I ship them out, more arrives to fill them. My wife is tripping over them which is not good either.
 

Cahudson42

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#7
$80 more gets you a Denon S540 5.1 receiver
Or a stereo Yamaha RS202 for $149..

https://www.crutchfield.com/p_022RS202/Yamaha-R-S202.html

And yes, both of these are 'full size' compared to this Fosi. But for that you likely get much better ventilation and unit life. Personally, I can always seem to find room somewhere, even my BR system with R162s and vintage RX-396. But I also don't worry at all about WAF..:)
 

Vini darko

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#9
By the way, the above is the 100th amplifier I have reviewed! Can you believe it? It seems it was just yesterday that I was happy to just be testing lightweight desktop products. I wanted to thank all the people who have sent these in for testing but my aching back doesn't allow it. :)
Happy 100th amplifier-day
 
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#10
Or a stereo Yamaha RS202 for $149..

https://www.crutchfield.com/p_022RS202/Yamaha-R-S202.html

And yes, both of these are 'full size' compared to this Fosi. But for that you likely get much better ventilation and unit life. Personally, I can always seem to find room somewhere, even my BR system with R162s and vintage RX-396. But I also don't worry at all about WAF..:)
I'll take that yamaha over many other budget amps.
 

Willem

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#11
I will happily argue with friends that good audio does not need to cost a fortune, but there is also a sensible minimum below which you no longer get value for your money. In my view with integrated amps this sensible minimum is reached with the 2x85 watt Yamaha AS 501. You get tone and balance control, loudness, plus mm phono and digital, and excellent measurements. Here in Europe it costs about 350 euros.
 
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MZKM

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#12
AVRs are huge though so I don't see them being a proper replacement for these amplifiers where you want to stick a piece of furniture and have some music.
I forgot the Topping MX3 exists at just $130, though is slightly less powerful but is an integrated amp. The Topping PA3 is $105 and would be a direct competitor to this Fosi amp, as is the SMSL SA98E.
 
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#15
Yamaha a-s201/301/501, cheaper pioneer, onkyo, teac, denon. Lots of options, albeit large size. Well sometimes you've got to crack a few eggs to make an omelette.
 

Feanor

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#16
Sorry, Amir. I admire your efforts but what I'm getting weary of is endless reviews of tinny desktop equipment. Who really cares?

I want more reviews of substantial 'main system' components like Purifi amps and, yes, the Parasound preamp.
 
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#17
Sorry, Amir. I admire your efforts but what I'm getting weary of is endless reviews of tinny desktop equipment. Who really cares?

I want more reviews of substantial 'main system' components like Purifi amps and, yes, the Parasound preamp.
Amir is limited to what people send him. Seeing how economy is performing it is unlikely we'll see any hardcore stuff.
 

Willem

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#19
I admire Amir's efforts, but given that he is already stretched reducing the number of tiny boxes may not be a bad idea. The question remains whether people will send him the heavy boxes. But I agree, those would be at least as interesting, and are sometimes underepresented.
 
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