Fosi Audio BT20A Pro Amplifier Review

[pma]

Wow, another toy with quite terrible parameters gets “recommended” verdict. Seems to be a rule of thumb. I do not believe that recommendations are based mainly on parameters. At least here does not exist any list of parameters to be fulfilled for the component to get a recommendation. It is purely subjective opinion of the reviewer.

 

[Talisman]

Wow, another toy with quite terrible parameters gets “recommended” verdict. Seems to be a rule of thumb. I do not believe that recommendations are based mainly on parameters. At least here does not exist any list of parameters to be fulfilled for the component to get a recommendation. It is purely subjective opinion of the reviewer.

can you argue?
the price is around 100 euros per unit with a 48V power supply
seems to offer an incredible power level of about 150w at 4ohm and 100 at 8, provides a bluetooth input and a preamp line out, has very good noise and distortion control, even in multitone it seems to perform very decently, the only the problem is the dependence on the load, but it still seems to be contained within acceptable values (a few db and only at the extreme high band, where probably few hear, around 15khz it should be about a db), moreover it has well implemented tone controls and finally a volume with logarithmic increase. Why shouldn't he recommend an amplifier with these features for just 100 Euros?

 

[Joe Smith]

Wow, another toy with quite terrible parameters gets “recommended” verdict. Seems to be a rule of thumb. I do not believe that recommendations are based mainly on parameters. At least here does not exist any list of parameters to be fulfilled for the component to get a recommendation. It is purely subjective opinion of the reviewer.

Well, no, it's definitely more than subjective. I think Amir does a nice summary job with the specs and measurements he posts. Personally, I feel it's not accurate to discount these little class D amps as "toys" because they are perfectly good at filling a wide range of use cases, and they are steadily improving in reliability and sound quality. And yes, compared to some of the other offerings at this price point, the load dependence seems pretty good. I still have a pair SMSL SA-50 amps from 8-10 years ago that are still running just fine, so for a lot of folks, these mini-amps are a good & simple solution for decent amplification needs with a very compact footprint.

 

[Extreme_Boky]

It is not a toy. It is an amplifier with 2x150 - 200W per channel, and it comes with a 48V/5A power supply. All that for less than $100 (with a discount code, from the manufacturer's site). It also measures quite well, has Bluetooth, and has tone controls with a proper bypass middle setting.

The fact that it is the size of a toy (well-built + aluminium), but provides all of the above, is an achievement in itself.

 

[Deleted member 48726]

can you argue?
the price is around 100 euros per unit with a 48V power supply
seems to offer an incredible power level of about 150w at 4ohm and 100 at 8, provides a bluetooth input and a preamp line out, has very good noise and distortion control, even in multitone it seems to perform very decently, the only the problem is the dependence on the load, but it still seems to be contained within acceptable values (a few db and only at the extreme high band, where probably few hear, around 15khz it should be about a db), moreover it has well implemented tone controls and finally a volume with logarithmic increase. Why shouldn't he recommend an amplifier with these features for just 100 Euros?

The load dependency doesn't at all translate from what you are implying to a real load. So there's that.

 

[Deleted member 48726]

It is not a toy. It is an amplifier with 2x150 - 200W per channel, and it comes with a 48V/5A power supply. All that for less than $100 (with a discount code, from the manufacturer's site). It also measures quite well, has Bluetooth, and has tone controls with a proper bypass middle setting.

The fact that it is the size of a toy (well-built + aluminium), but provides all of the above, is an achievement in itself.

2x150 W
48 V / 5A
Hmm.. Which is it?
Otherwise I agree that it for some people could be a great value product. For less than 100 usd this is better than many other products at this price.

 

[Deleted member 48726]

I think our friends here are talking about CONFORMITY TO THE BROCHURE.

Looks to me like my kid throwing a tantrum over some insignificant thing.. Wanting to return the thing because of the colour on the volume knob seems a bit off. But fair enough and to each their own.

 

[JSmith]

Just to try and clear up this volume knob issue... the orange knob comes with the blue version, the grey knob comes with the grey version. Unsure why Fosi sent Amir a blue version with a separate orange knob @Fosi Audio?

This is as per Aliexpress and Fosi Audio Shop;

https://www.aliexpress.com/item/1005005310845326.html

Fosi Audio BT20A PRO 300W x2 TPA3255 2 Channel Bluetooth 5.0 Power Amplifier

Experience Hi-Fi audio with the Fosi Audio BT20A Pro home amplifier. Enjoy 300W x 2 power output, upgraded Bluetooth 5.0 connectivity, and sound controls.

fosiaudioshop.com

However if a customer has purchased from a vendor that gives no colour options and shows the blue/orange version... that is what a customer should get and is grounds for a return for sure. Or are people receiving the blue version with a blue knob and no orange knob as separate?

This site for example doesn't give an option for colour or power supply choice;

FOSI AUDIO BT20A PRO Class D Amplifier TPA3255 Bluetooth 5.0 2x225W 4 Ohm - Audiophonics

The Fosi Audio BT10A PRO is a small, compact and powerful Class D amplifier, offered at a resonnable price. Its amplification stage uses a TI TPA3255 chip, capable of developing a power of 2x300W under 4Ω with a high efficiency.

www.audiophonics.fr

* Note, these can be purchased without a power supply too at some sites.


JSmith

 

[Kimbrough Xu]

Just got my Fosi BT 20 A pro from Amazon, but I'm a little surprised:

Mine doesn't have the bronze-colored volume knob which is visible in all the ads, videos, and such. Everything else is as advertised.

View attachment 278979

Do you select the Grey version from the fosi website https://fosiaudioshop.com/products/bt20a-pro-2-channel-bluetooth-power-amplifier? They seems to provide 2 colors for selection, the blue version with copper knob, and the grey version just with a grey knob.

 

[Fosi Audio]

Just got my Fosi BT 20 A pro from Amazon, but I'm a little surprised:

Mine doesn't have the bronze-colored volume knob which is visible in all the ads, videos, and such. Everything else is as advertised.

View attachment 278979

We should apologize for the inconvenience and any annoyance caused by it. I‘ll DM you and we will help you solve this problem right away.

 

[Fosi Audio]

Very disappointed, my unit also only features the gray knob, despite the very distinctive nice bronzed knob being shown in all the pictures.
I almost want to return it, it bothers me a lot.
@Fosi Audio can you explain why it is advertised everywhere with the orange knob and then not supplied?
View attachment 279025

Sorry for the inconvenience and any annoyance caused by it. I‘ll DM you and let's solve this problem right away.

 

[Fosi Audio]

Just to try and clear up this volume knob issue... the orange knob comes with the blue version, the grey knob comes with the grey version. Unsure why Fosi sent Amir a blue version with a separate orange knob @Fosi Audio?

View attachment 279069

View attachment 279070

This is as per Aliexpress and Fosi Audio Shop;

https://www.aliexpress.com/item/1005005310845326.html

Fosi Audio BT20A PRO 300W x2 TPA3255 2 Channel Bluetooth 5.0 Power Amplifier

Experience Hi-Fi audio with the Fosi Audio BT20A Pro home amplifier. Enjoy 300W x 2 power output, upgraded Bluetooth 5.0 connectivity, and sound controls.

fosiaudioshop.com

However if a customer has purchased from a vendor that gives no colour options and shows the blue/orange version... that is what a customer should get and is grounds for a return for sure. Or are people receiving the blue version with a blue knob and no orange knob as separate?

This site for example doesn't give an option for colour or power supply choice;

FOSI AUDIO BT20A PRO Class D Amplifier TPA3255 Bluetooth 5.0 2x225W 4 Ohm - Audiophonics

The Fosi Audio BT10A PRO is a small, compact and powerful Class D amplifier, offered at a resonnable price. Its amplification stage uses a TI TPA3255 chip, capable of developing a power of 2x300W under 4Ω with a high efficiency.

www.audiophonics.fr

* Note, these can be purchased without a power supply too at some sites.


JSmith

Please allow me to explain about the knobs.

We have developed and made two colors of the BT20A Pro. A blue version with a metallic orange volume knob, and a grey version with a grey volume knob. Initially, we planned to gift an extra blue volume knob to the blue version. However, we got feedback from our beta testers that the orange knob is preferable. So finally we decided to cancel giving that extra knob to the blue version. By the way, we sent a blue set with an extra blue knob to Amir for this measurement.

Anyway, we will probably provide the option of buying an extra knob online in the future.

 

[TonyJZX]

williston

48v 5.0 amp included in his box
105w @ 8
160w @ 4

32v 5.0 amp as oem

40w @ 8
70w @ 8

these are all 1% so expect a little less with realistic thd... peak is even more

his came with orange knob and no grey knob

also in the epilogue he tried it at 2 ohms and it circuit breaker saved itself so its not 2 ohm capable but this was to be expected

however it did get to 75w so does that mean in NORMAL volume operation up to 70w (for example) it would be ok???

 

[Talisman]

however it did get to 75w so does that mean in NORMAL volume operation up to 70w (for example) it would be ok???

Depends what you mean by normal.
you definitely can't run it at 70 watts continuous, first because it's hell of a volume, second because you'd have no headroom and any slight peaks would be heavily distorted.
having 70 watts means that you can also use a continuous power of 5/7 watts and keep a margin to still have a fair amount of space for the peaks without clipping and without sending everything into serious distortion.
continuous volume at 7 watts is really loud in the home

 

[TonyJZX]

firstly i would say that if you truly had 2 ohms speakers dont use this

however it seems to be that as long as you keep the volume reasonable... ie. 90dB or less which is more than ok for most domestic use guveb avg sensitivity then this would work

but the caveat would be that the unit would heat up pretty damn quick BUT stay at constant level given that

purely an academic thought exercise really

 

[DavidM1]

Agreed, and add a remote control, and if the two or three analog inputs have a XLR input can be better.

+1 for balanced amplifier inputs.

 

[sound67]

Do you select the Grey version from the fosi website https://fosiaudioshop.com/products/bt20a-pro-2-channel-bluetooth-power-amplifier? They seems to provide 2 colors for selection, the blue version with copper knob, and the grey version just with a grey knob.

No, I ordered it off German Amazon, which only displays the version with the bronze/orange knob:

https://www.amazon.de/gp/product/B07JVFY27T?ref=ppx_pt2_dt_b_prod_image

There is no other version displayed on German Amazon. It appears Amazon have missed up by sending me he grey version.

But Fosi Audio have reacted quickly and promised to send me the orange knob separately.

 

[Jacob8275]

The volume control potentiometer is tapers A or B?

 

[sound67]

I have now mounted my Fosi BT20A Pro with a pair of Q Acoustics 3030i as my new, passive desktop setup (replacing a pair of ADAM A5 active speakers).

The first thing that strikes me is how high I have to turn up the volume on the Fosi, considering my ears are less than 1 meter away from the speakers, and they're 88db into 6Ohms. I got the version with the 32V-5A standard power supply. Having said that, the sound is really good (had to turn the bass down and the treble up a bit). I'm using the output of my OPC soundcard for the time being.

The Q 3030i were previously set up in my bedroom (4 by 5 meters), connected to my Aiyima D03 (36V-6.5A). In that setup, I only had to turn up the D03 to about 45% for a slightly louder than comfortable volume. On the Fosi/Desktop, it's more like 60% for comfortable listening (PC output at 100%).

Would it make sense to order a 48V power supply for the Fosi?

 

[delta76]

Wow, another toy with quite terrible parameters gets “recommended” verdict. Seems to be a rule of thumb. I do not believe that recommendations are based mainly on parameters. At least here does not exist any list of parameters to be fulfilled for the component to get a recommendation. It is purely subjective opinion of the reviewer.

please show me a "not terrible"/significantly better amp for ~100$/100EUR

I'll wait.