Fosi Audio BT20A Pro - Opinions and Comparisons

[Jeromeof]

Fosi Audio kindly sent me a pre-release version of the BT20A Pro a month or so ago and I have been swapping it around with a few other similar Class D amplifiers that I already have, specifically the other TPA3255 models I have the A07 and the A07 Pro.

I do hope Fosi Audio have sent a model to @amirm for testing but I thought I would share my opinions in this thread in the mean time.

Executive Summary:
If you are looking for something that sounds the same / as good as the A07 or the TB10D (with similar output capabiltiies) but with a great tone control implementation and support for bluetooth then this is probably the new best in class Amp. It also looks better IMO - without any screw showing. Here are some pictures:

Pros:

• Great sound - IMO matching the A07 see details below
• Great Tone controls - love the click to show they are in the central position. All the volume buttons are very "satisfactory" - they don't feel cheap
• Bluetooth implementation is clean - IMO this is better than the A07 Pro (which was very noisy in the model I have)
• Looks nicer IMO than other similar class D amps
• Very small and compact (though this can be a con see below)

Other considerations (possible cons or things Fosi could have done better):

• Bluetooth while it sounds clean (little or no noise compared to the A07 Pro) it just supports the SBC codec (so no AAC or LDAC)
• Bluetooth cannot be fully disabled - but you can disconnect by pressing the power button
• Its a much smaller box than the A07 Pro - so heat might be a problem if played loud for a long time - I imagine if op-amps are swap maybe some extra vents would be drilled into case

Sound over RCA:

This amp with the Tone controls "defeated" (and they have a lovely satisfying click in the central position so you the bass and treble are disabled) sound exactly the same as the A07 - I even went as far as doing a few sweeps with a Umik microphone and REW with both the A07 and the BT20A Pro and got incredible similar graphs. I can post the graphs but mostly they just show my speakers FR (as they should IMO).

With the Tone controls enabled it was able to get a nice sound in my listening space without EQ - I typically just need to lower the treble a little for my own tastes. I can capture some comparisons if people are interested of the max / min of both the bass and treble dials.

Sound over Bluetooth:
This amp was much cleaner over bluetooth than the A07 Pro (or other similar bluetooth implementations I have tried in the past) - my not very scientific approach is to play something totally quiet and listen in the near field to any noise coming out speakers - this amp was the same over bluetooth and RCA as far as that subjective test was concerned. The A07 Pro was not. Hopefully there will be more definitive measurements release here soon.

Some Measurements from Fosi Audio themselves
Yes this possible can't be trusted as its the vendors own measurements but I noticed yesterday the released a page with some details

Fosi Audio BT20A PRO

The Fosi Audio BT20A Pro is a new generation Bluetooth amplifier integrating the high-performance Texas Instruments 3255 amp chip, which can bring up to 300W power per channel and allows ultra-low distortion across the audio band and superior audio quality.

www.fosiaudio.com

And for those not wanting to click the link here are the 2 important charts from that page:

And the Sinad is very competitive - I believe this would fall into Amirs "very good" ranking - hopefully independently verified soon:

Overall comparisons with the other TPA3255 amp that I compared it with (and this is totally my opinion):

1. Compared to the A07 Pro: Bluetooth implementation much cleaner - if similar priced - though not sure what the final price will be - this is the better amp - I do see they have 30% off - though Aiyima do also run lots of deals)
2. Compare to the TB10D: It has a better tone control implementation / Bluetooth
3. Compared to the A07: If you don't want tone controls and Bluetooth maybe stick with the A07 ( as no doubt it will be cheaper) but this IMO is a great upgrade.

 

[Kimbrough Xu]

Have you tested the specs yourself?

 

[tomtoo]

I like the look in grey.

 

[Jeromeof]

Have you tested the specs yourself?

No, hence why I mentioned it would be great if Amir was sent a copy for testing.

I did test and compare the outputs with the A07 and I did a 'human' subjective test for noise (near field speaker setup with high volume playback playing a 'silent' track) and it was as good as the A07 - which I know doesn't mean it is - but I given what Fosi Audio published I would hope it is (as they would be found out once Amir does test this Amp fully).

I also swapped the power supplies around and played as loud as I could bare (without annoying the neighbours). Mine came with a 32V 5Amp - but I swapped for a 36V 6Amp and it worked as well as the 2 Aiyima's. I imagine given its the same chipset it should support a similar power ratings. The only thing I would say it is more compact that the A07 Pro so might be more susceptible to getting hot (though I didn't play it for long enough and loud enough to feel much heat).

I am looking at getting some equipment that can be some basic Amp / DAC testing (though I think an AP will always be beyond my budget), so hopefully in future.

 

[Jeromeof]

I like the look in grey.

Not sure why but I got 2 coloured volume buttons, possible Fosi Audio hadn't decided which colour for the buttons but they may have now.

 

[tomtoo]

Not sure why but I got 2 coloured volume buttons, possible Fosi Audio hadn't decided which colour for the buttons but they may have now.

I like that grey case with that copper volume knob. From my point of view it looks tasty.

 

[Fosi Audio]

Bluetooth while it sounds clean (little or no noise compared to the A07 Pro) it just supports the SBC codec (so no AAC or LDAC)

Thank you so much for your review. Actually, the BT20A Pro supports the AAC codec.

 

[isaac507]

Looks great. It's so nice to see Fosi has created an amp to allow rolling the op-amps.

 

[Jacob8275]

Got a 30% off early bird discount, Looking forward to testing.

 

[jfort]

Input/Output:

 

[Fosi Audio]

Not sure why but I got 2 coloured volume buttons, possible Fosi Audio hadn't decided which colour for the buttons but they may have now.

Yes, we're trying different colors that we haven't used before.

 

[tomtoo]

Do i have the BT signal on the pre out?

 

[Jeromeof]

Do i have the BT signal on the pre out?

I believe it does - but I can verify again later on. I wasn't that focused on BT so only tried the basics to see if it sounded good - my personal opinion is, while it's nice to have the option (e.g. if friends call over and want to play something), mostly I would use RCA inputs from a DAC and/or Wiim Mini or similar streamer.

 

[tomtoo]

I believe it does - but I can verify again later on. I wasn't that focused on BT so only tried the basics to see if it sounded good - my personal opinion is, while it's nice to have the option (e.g. if friends call over and want to play something), mostly I would use RCA inputs from a DAC and/or Wiim Mini or similar streamer.

Thx, would be nice to know.

 

[Jeromeof]

OK - I set it up again and tested the PreOut via Bluetooth and all is working as expected. Since I had it setup I decided to do some quick measurements in REW - these are with a pair a Q3020i and a not particular good Yamaha Subwoofer (so while the Yamaha doesn't exactly fill out the bass it does add a little in this setup):

Mostly this shows that this room needs some treatment -But say the initial black line is the completely neutral (with the tone controls defeated) - this shows that the Q 3020i's are bright (which I knew - I normally runs these with a Denon Amp and Audyssey) - but then the other 2 measurements show the I lowered the treble and it immediately fixes that issue The cyan measurement was then be adding the pre-out Yamaha Sub - which added a bit more bass (but it is not a great sub only adds a bit) - but then with the bass control on the Fosi-Audio I decided to dial back the bass but then up the gain on the Sub resulting in the Red measurement so a little better IMO.

Anyway, I hope this shows what I think is the big advantage of well implemented tone controls in an amp and the ability to blend the Sub output to provide some level of tweaking the sound to your tastes.

While having all these connected I thought it might be good to get a picture of the back of this amp "fully loaded" - because its so compact its a bit messy - but everything has just about enough space. So here are a few more pictures of it:

 

[tomtoo]

Thx!

 

[mocenigo]

Yes, we're trying different colors that we haven't used before.

The board is very similar to the 3eaudio ones – it looks like a customised project. Is this implementation with PFFB?

Roberto

 

[Justus_Jonas]

looks like the amp arrived in Europe:

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

when will they be available at Amazon (esp Germany)?

Regards
jj

 

[Justus_Jonas]

Hello, here is a video about the internal pcb etc...

Fosi Audio

Fosi Audio. 4,203 likes · 204 talking about this. Fosi Audio official Facebook page

www.facebook.com

any Thoughts??
good... bad... ??

 

[Fosi Audio]

looks like the amp arrived in Europe:

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

when will they be available at Amazon (esp Germany)?

Regards
jj

It's still on the way to Europe actually. It will be available at Amazon Germany before April 10.