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Fosi Audio HD-A1 Budget Amplifier Review

Xulonn

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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.

In October, 2018 Amir reviewed - and panned - the similar Topping TP-60 class-AB amplifier that costs about $200. Although it also fell short of rated power (60wpc vs a 80wpc rating, and reached its rating if more distortion is allowed), it measured 8dB better in SINAD than the Fosi HD-A1.

Both the Topping (based on a very old Tripath "class-T" chip, which is Tripath's designation for their early high-frequency class-D designs) and this Fosi indicate to me that for desktop-style stereo amplifiers, these linear power supplies with big, heavy toroidal transformers do not appear to offer any advantage over switching power supplies. ( I may review the ASR list of measured amplifiers to see if I can confirm this.)

I use an I.AM.D v200 ($95) with a TAS5614LA chip to drive the Q-Acoustics 3010's on my desktop. It does its job with no audible deficiencies, and like it, although I doubt that it produces it's TI rated 125wpc @ 4Ω and 1% distortion. But it has so far been more reliable than the two Topping PA-3's that died on me. I had a following on the DIY Audio forum for a while, but it is likely too obscure for one to end up in Amir's measurement queue.

I.AM.D v200-3.jpg
 

F1308

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Willem

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Do you have a link for it being tested?
Its virtually identical (apart from the new digital inputs) the Yamaha AS500 was tested with a lot of serious measurements by an Australina hifi publication that has since been sold. So I cannot find the link anymore. But the short summary is that it measured exceptionally well. I think of the three budget Yamahas the AS 5021 occupies the sweet spot in many markets, Here in the Netherlands the cheaper and less powerful AS 301 is hardly cheaper and quite a lot less powerful, whereas the more powerful AS701 is not that much more powerful, but is quite alot more expensive. However, I note that unexpectedly these Yamahas are quite a bit cheaper in Europe than in the USA.
 
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kfaiman

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I was also in the market for a cheap speaker amp for my desktop speakers (4 Ohm, 91dB). Rolled the dice on a SMSL DA-8S ($170) that uses the Infineon MA12070 Class-D module. Specs claim 80 Watts (4 Ohms), THD+N 0.008%, SNR 90dB, BT 5.0 (AirPlay worked), XLR inputs. I'm super impressed at this price point, would love to see a review down the road.
 
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amirm

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Looks like there is no safety ground. And those speaker terminals are away too close to the transformer input mains wires for my comfort. The transformer needs to be rotated away from speaker terminals.
 

Jimster480

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The performance is just ATROCIOUS. You should test out that cheap topping speaker amp and see if its any better. I think its like the TP60?
 

restorer-john

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Looks like there is no safety ground.

In that shot I posted it doesn't look like it. The youtube review you linked however, there appears to be a safety ground (thank goodness)

1595285176599.png
 

5th element

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What doesn't make sense is that standard blameless amplifier designs have been around for years. This amplifier already has the expensive stuff sorted. A few extra small signal transistors and resistors and you'd have almost as good as it gets, with the SINAD only falling short of the very best. I don't get the point of this amplifier, the designer needs to buy a book or two on amp design and read them.
 

Bruce Morgen

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Inadequate or poorly integrated power supplies are the downfall of many "budget" amps. One is much better off getting one that requires external power -- that way, you can be assured of adequate current sourcing via choosing an appropriate power supply. I've had (what to my ears are) good results with sub-$100 Chinese-made "chip amps" based on TI's TAS5630 and TPA3255 Class D ICs when teamed with a generic SMPS that provides enough current for those surprisingly capable chips to perform up to spec.
 

Xulonn

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The performance is just ATROCIOUS. You should test out that cheap topping speaker amp and see if its any better. I think its like the TP60?

From my above post up-thread a bit:
In October, 2018 Amir reviewed - and panned - the similar Topping TP-60 class-AB amplifier that costs about $200. Although it also fell short of rated power (60wpc vs a 80wpc rating, and reached its rating if more distortion is allowed), it measured 8dB better in SINAD than the Fosi HD-A1.

Both the Topping (based on a very old Tripath "class-T" chip, which is Tripath's designation for their early high-frequency class-D designs) and this Fosi indicate to me that for desktop-style stereo amplifiers, these linear power supplies with big, heavy toroidal transformers do not appear to offer any advantage over switching power supplies. ( I may review the ASR list of measured amplifiers to see if I can confirm this.)
 

mshenay

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Yea I reviewed one of their Dac Amp products a few years back... frankly the brand is very underwhelming even from a subjective point of view :/

Not surprised to see the kinda ehh measurements
 

valerianf

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I am still searching for a small form factor stereo amplifier with remote.
Clearly it will not be that one.
There may exist some dedicated to the Japanese market, but they may be vintage.
 

Kaiju

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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.

Show us your storage. let us feast our eyes.
 

gvl

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I would have felt cheated if I paid $200 for this. ICEpower 50ASX2SE + Ghent Audio case is not much more $$ but should perform better, alas, no volume control.
 

renaudrenaud

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I would have felt cheated if I paid $200 for this. ICEpower 50ASX2SE + Ghent Audio case is not much more $$ but should perform better, alas, no volume control.
I am able to let the volume control on the road for +30dB of SINAD.
 

BillG

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I use an I.AM.D v200 ($95) with a TAS5614LA chip to drive the Q-Acoustics 3010's on my desktop...

I've one as well, although it's retired at the moment, and replaced by a Klipsch PowerGate. I took it out of storage a couple of months back for a three day spin, and I was still impressed with what I heard considering its cost. But then again, we're all well aware around here that human hearing is rather immune to flaws unless they're going beyond moderate and into the extreme.

I think I may have been the person that actually recommended this amp to you... :)

I've seen a couple of independent performance analysis for it around, and, if I recall correctly, it managed to pass what would be considered the lenient thresholds for transparency as defined by ASR and associates... ;)
 
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