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Fosi Audio BT10A Bluetooth Stereo Amp Review

Jeephead said:
I am using this amp and am surprised how well is sounds. I actually connected my Schiit Headphone set up to it. I am currently running a Magni, Modi Dac, Loki EQ, and a Mani phone pre-amp through a SYS. I use a Raspberry Pi running Moode audio going to DAC. I do not use the BT for streaming music. The bass and treble controls are helpful on the Fosi but the additional Loki EQ really helps the lo/hi end roll off of the Fosi. I send this all to a pair of Bose AM5 dual cubes and sub. It is in a small room for near field listening of vinyl and digital. It really makes the Bose finally sound good. Not my ideal setup but good for what I had on hand. Wanted a Schiit Vidar $699 or an Emotiva Basx A-100 $239. Schiit is not in the budget. Emotiva is doable but it seemed to not get a favorable test result here and I am not sure how much better it will make speakers sound with my setup. Class A/B vs D is sure to sound better but do I really need to improve? Thoughts?
Click to expand...
Welcome Aboard @Jeephead.
 
I sent my Fosi HD-A1 in for testing. It seemed pretty decent in my YouTube review but the measurements are crap. IF your a critical listener I'd stay away from the HD-A1 it's barely capable of resolving a record or cassette tape. Aiyima A07 is cheaper and better.
 
Does the latest version with Tone controls perform any differently, better /worse?
 
Don't know about the BT10A, but I returned the BT20A as the sound it gave did not really impress me.
 
cancunia said:
Don't know about the BT10A, but I returned the BT20A as the sound it gave did not really impress me.
Click to expand...
The BT10A uses one TPA3116D amplifier chip to output 2ch stereo. The BT20A consists of two TPA3116Ds, one for each of the left and right channels. Therefore, BT20A has twice the output power of BT10A.
Also, the power switch of BT20A is turned on / off with a dedicated toggle switch, but for BT10A, the power is turned on / off by turning the volume knob.
In addition, the BT10A comes with a 19V power adapter and the BT20A comes with a 24V power adapter, which is more powerful.
 
amirm said:
This is a review and detailed measurements of the Fosi Audio BT10A Bluetooth Class D stereo amplifier. It is on kind loan from a member. The B10A seems to have just been updated with tone controls and sells for US $50 from Amazon with free prime shipping.

This is a very small amplifier:


You can't see the depth but it is quite shallow. Other amps like this I have tested have complicated interface to change built-in digital tone controls. There are none here so it was easy to use.

The back connectors is identical to what you see on myriad of such amps:
While the external laptop replacement power supply is large compared to the size of the unit, it is not as huge as some others. Note that it comes with a three-prong, figure-8 AC socket so you have less options to replace the cord.

I did not bother testing the Bluetooth. I am assuming it autoselects it if in range as the priority input as there is no switch to select it.

Speaker terminals are tiny of course but I managed to plug in my heavy and large banana jacks into it.

Amplifier Audio Measurements
As usual, we start with our dashboard view of 1 kHz tone into 4 ohm load with volume adjusted for 29 dB gain (THX recommendation):
View attachment 43345

Second harmonic dominates to the tune of -65 dB which sets the SINAD to the same value. This says that noise is not a contributor to SINAD and as such, any gain setting would have produced similar SINAD. The 65 dB SINAD value doesn't put a smile on anyone's face but it is a couple of steps above $30 units (e.g. Lepy LP-2020A):

View attachment 43346

Noise figures are barely adequate:
View attachment 43347

32-tone test signal shows more or less uniform distortion at all frequencies:

View attachment 43348

19+20 kHz tones shows 55 dB of distortion-free range:
View attachment 43355

Their full (and unrealistic) amplitude shows higher distortions than multitone test does.

Frequency response shows truncated low and high frequencies:
View attachment 43349

Above with a resistor load. Subjective the amp to my new complex speaker model of a 2-way speaker generates:
View attachment 43350

The speaker model has a its impedance shooting up in high frequencies causing similar issue here. There is a question of whether the model is similar to mass of 2-way speakers so don't run with this yet. What you can conclude is that the speaker choice does impact the speaker response. In audible band though, the impact is minimal and in some way is correcting the dip toward 20 kHz. A good amp would have no speaker load dependency.

Let's see how much power the BT10A can produce into 4 ohm load:
View attachment 43351

At 33 watts with both channels driven this is good bit of power. Similar story with 8 ohm load:
View attachment 43352

Lack of power is by far the #1 issue in these amplifiers. You may not be able to hear their noise and distortions but you absolutely will hear them complain when they clip. At these power levels you should have a reasonable experience unlike some other budget amps that stop at 10 watts or so.

Allowing for more distortion (1% THD+N) and testing with a short-term sinewave and long term produces identical numbers:
View attachment 43353

The input power supply is regulated so there is no reservoir to provide short-term juice.

Thermal Stability
Performance gradually improved by a 2 dB or so after 30 minutes of playing at 5 watts:

View attachment 43354

Above tests were performed after this warm-up period.

Conclusions
The Fosi Audio BT10A doesn't seem half bad. I am not going to provide a verdict one way or the other. You can decide for yourself if the performance is good enough for your application.

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

You know the money situation is bad when I have to get a $50 amp on load to test! So please, help improve my bank account balance by donating as much as you can using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Click to expand...

Very similar to the Mini Amplifier V1.0B, I would like to know if they have updated the internals.
 
amirm said:
This is a review and detailed measurements of the Fosi Audio BT10A Bluetooth Class D stereo amplifier. It is on kind loan from a member. The B10A seems to have just been updated with tone controls and sells for US $50 from Amazon with free prime shipping.

This is a very small amplifier:


You can't see the depth but it is quite shallow. Other amps like this I have tested have complicated interface to change built-in digital tone controls. There are none here so it was easy to use.

The back connectors is identical to what you see on myriad of such amps:
While the external laptop replacement power supply is large compared to the size of the unit, it is not as huge as some others. Note that it comes with a three-prong, figure-8 AC socket so you have less options to replace the cord.

I did not bother testing the Bluetooth. I am assuming it autoselects it if in range as the priority input as there is no switch to select it.

Speaker terminals are tiny of course but I managed to plug in my heavy and large banana jacks into it.

Amplifier Audio Measurements
As usual, we start with our dashboard view of 1 kHz tone into 4 ohm load with volume adjusted for 29 dB gain (THX recommendation):
View attachment 43345

Second harmonic dominates to the tune of -65 dB which sets the SINAD to the same value. This says that noise is not a contributor to SINAD and as such, any gain setting would have produced similar SINAD. The 65 dB SINAD value doesn't put a smile on anyone's face but it is a couple of steps above $30 units (e.g. Lepy LP-2020A):

View attachment 43346

Noise figures are barely adequate:
View attachment 43347

32-tone test signal shows more or less uniform distortion at all frequencies:

View attachment 43348

19+20 kHz tones shows 55 dB of distortion-free range:
View attachment 43355

Their full (and unrealistic) amplitude shows higher distortions than multitone test does.

Frequency response shows truncated low and high frequencies:
View attachment 43349

Above with a resistor load. Subjective the amp to my new complex speaker model of a 2-way speaker generates:
View attachment 43350

The speaker model has a its impedance shooting up in high frequencies causing similar issue here. There is a question of whether the model is similar to mass of 2-way speakers so don't run with this yet. What you can conclude is that the speaker choice does impact the speaker response. In audible band though, the impact is minimal and in some way is correcting the dip toward 20 kHz. A good amp would have no speaker load dependency.

Let's see how much power the BT10A can produce into 4 ohm load:
View attachment 43351

At 33 watts with both channels driven this is good bit of power. Similar story with 8 ohm load:
View attachment 43352

Lack of power is by far the #1 issue in these amplifiers. You may not be able to hear their noise and distortions but you absolutely will hear them complain when they clip. At these power levels you should have a reasonable experience unlike some other budget amps that stop at 10 watts or so.

Allowing for more distortion (1% THD+N) and testing with a short-term sinewave and long term produces identical numbers:
View attachment 43353

The input power supply is regulated so there is no reservoir to provide short-term juice.

Thermal Stability
Performance gradually improved by a 2 dB or so after 30 minutes of playing at 5 watts:

View attachment 43354

Above tests were performed after this warm-up period.

Conclusions
The Fosi Audio BT10A doesn't seem half bad. I am not going to provide a verdict one way or the other. You can decide for yourself if the performance is good enough for your application.

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

You know the money situation is bad when I have to get a $50 amp on load to test! So please, help improve my bank account balance by donating as much as you can using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
Click to expand...

Should I believe that this amp is similar or the same as the Fosi Audio V1.0B TPA3116D2?
 

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Tangband said:
No, the sound can probably be even better with a better switched mode supply at 24 volt and 6 A. I have done a lot of testing with Tpa3116D2 and with different PSU:s. I can recommend psu:s from Meanwell.
The sound gets better if there is more than the usual 1000 uF at the input terminal.

With those conditions , 24 volt, 6 A and maybe 5000-6000 uF , the chip sound very clean up to the point if clipping.
Personally I rate the sound from a good implementation of the tpa3116D2 as sounding better than a LM3886 amp chip. ( I have a pair of those to ).
If you read the Texas instruments application notes of the tpa3116D2, you can se they have a bit better test result than this review. For example, you really need a psu with less than 200 mV ripple.
The psu:s following those cheap amplifiers are often crap.
The pictures below shows my own version of tpa3116D2 with a bigger external psu from Meanwell and capacitors ( 6*1000 uF ) from panasonic.
Click to expand...

Does it gets hot, will it shorten the lifespan?
 
Which bluetooth chip, is chinesium or Qualcomm? Can't find info anywhere which point to the cheap choice :-(
 
Last edited:
Tangband said:
No, the sound can probably be even better with a better switched mode supply at 24 volt and 6 A. I have done a lot of testing with Tpa3116D2 and with different PSU:s. I can recommend psu:s from Meanwell.
The sound gets better if there is more than the usual 1000 uF at the input terminal.

With those conditions , 24 volt, 6 A and maybe 5000-6000 uF , the chip sound very clean up to the point if clipping.
Personally I rate the sound from a good implementation of the tpa3116D2 as sounding better than a LM3886 amp chip. ( I have a pair of those to ).
If you read the Texas instruments application notes of the tpa3116D2, you can se they have a bit better test result than this review. For example, you really need a psu with less than 200 mV ripple.
The psu:s following those cheap amplifiers are often crap.
The pictures below shows my own version of tpa3116D2 with a bigger external psu from Meanwell and capacitors ( 6*1000 uF ) from panasonic.
Click to expand...

Does your amplifier run now on higher temps than with the regular 19v power supply? I see Mean Well also produces the 19v 4.74A power supply.
 
Laptop PSU from e.g. Lenovo, Dell and HP are usually very high quality, low noise, 19V, 65W-90W and usually easy to get cheap 2nd hand, if you not already have one.
 
Today of November 2024, I just got one from AliExpress.

It seems they have made some changes since the first BT10A models came out:
Productimage_600.png































Fosi BT10A board-01.png

The Bluetooth chip has been changed to a Xiamen ATS2853

Fosi BT10A BT-chip-00.png


-The volumen-button, with build-in on/off switch, is rather low quality
-The speaker terminals if also of rather low quality, e.g. cannot be used with spade-terminals

I whould choose the Aiyima A01 Pro over this Fosi any day - I got both.
But if the price is right for the Fosi, it can be a good buy
 
Last edited:
I find those speaker-terminals and DC-connectors to be a P.I.A!

The first thing I do is to get rid of them and solder wires directly and go the wago-way
Speaker and DC terminals.jpg

Same goes for my PSU's, no more fooling around with incompatible DC plugs, wago-way too:
LenovoPSU.jpg

(the wago-way does require wire-terminals, but that should be in your arsenal anyway!)
 

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  • WireTerminals.jpg
    WireTerminals.jpg
    45.1 KB · Views: 90
MrCal said:
Today of November 2024, I just got one from AliExpress.

It seems they have made some changes since the first BT10A models came out:
View attachment 403287






























View attachment 403289

The Bluetooth chip has been changed to a Xiamen ATS2853

View attachment 403288

-The volumen-button, with build-in on/off switch, is rather low quality
-The speaker terminals if also of rather low quality, e.g. cannot be used with spade-terminals

I whould choose the Aiyima A01 Pro over this Fosi any day - I got both.
Click to expand...
Recent Chinese products have replaced the BT chip with a Chinese designed IC chip.
 
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