Fosi Audio BT30D Pro review

[Pixelwarfare]

Compared to the BT30D non-Pro (left), the Pro version is quite a bit longer and heavier (430g vs 620g).

The knobs are made of aluminium, different texture compared to the no-pro, a bit more resistance to turn. Same throw switch used to power on.

The 3.5mm PRE OUT is full range.

Bluetooth will be always-ON so your neighbour can hijack your device just like the non-pro version. Remove the antenna to prevent this from happening if you don’t use BT. Come on Fosi Audio, please fix this.

The amp has a 4” tall BT antenna, again it's better than the 7” incher of the DA2120C that looks like a CB radio... Please give us the 1 incher for future products, for once the smaller the better.

The spec in the manual is different from the official website, give us the true data!!!

BT uses an ATS2853 chip that is also found on the BL20A.

How does it sound?

I did a comparison with Onkyo RZ50 pure output mode (airplay), Aiyima T9 (BT), and the BT30D non-Pro (BT). All using RP5000F towers, with an amp selector switch.

Right away there’s a BIG difference between the non-Pro and the rest.

The Pro version is much more dynamic, the voices are clearer, bass is more present and punch harder.

I honestly cannot tell any audible difference between the RZ50 and the BT30D Pro. The T9 sounds only a tad warmer (thx lamp); Even that it was really hard to tell and it depends on the song being played.
The Pro version sounds definitely better than the non-Pro.

To test the passive sub output, I hooked up my gutted Z2300 logitech subwoofer, it works wonderfully and has a very capable output. However, I didn't like the sub crossover control, the adjustment doesn't feel linear. There are no frequency indications on the knob, it can only be tuned by ears.

Now the technical stuff:

The PCB: The board is very well built

Caps:

Relay: It does the click (barely audible) only during power on. Maybe that's why no more sparks.

The muscle: TPA3255 x 2:

PSU idle voltage: 32.3V

Power adapter output @ 8ohm load current and voltage, 125W:

Same 32V5A adapter used for multiple models. No sparks occurred while plugging in the DC plug compared to the DA2120C I've tested, I made multiple attempts to make sure this is repeatable.

Here I am trying to figure out the max usable volume before getting a bad shaped sine wave, The volume knob is at 3 o'clock, BT reference volume maxed out on my mobile device, no EQ, no tone.

L & R Channel, 8 Ohm load, 1000hz tone, 26Wrms per channel

L & R Channel, 8 Ohm load, 1000hz tone, clipping at 60Wrms

L & R Channel, 4 Ohm load, 1000hz tone, 40Wrms per channel

L & R Channel, 4 Ohm load, 1000hz tone, clipping at 100Wrms

Sub channel @ 4 Ohm load, 75Wrms:

Sub channel @ 4 Ohm load into clipping, 121Wrms:

Noise, tested with max volume:
BT30D non-Pro, audible hiss from speakers during powerup, circuit shuts off when no input signal for 5 secs to prevent constant hissing.

BT30D Pro, barely audible hiss from speakers, you have to stick your ear on the tweeter to hear it. no circuit to shut off the signal, it's not needed because it is not audible sitting away from speakers.

The TPA3255 chips are hungry AND efficient. If you can feed them, they will put out a respectable amount of power for its size. You can upgrade to a 36V power adapter if you are looking to squeeze more juice out of it. It seems most of the manufacturers using this chip have set the bottleneck to the power supply. If you are looking for a 2.1 amplifier with passive sub output, look no further.

The BT30D Pro is way better than the non-Pro version.


Pros:

• Great build quality
• Excellent sound quality, to my ear it’s on par with the Aiyima T9 and RZ50
• Low noise floor
• Runs cool and efficient

Cons:

• Cannot turn BT off
• Sub frequency needs indication and more linear tuning
• Power limited by the power supply
• 1" BT antenna plz

 

[Graham849]

This would be a great amp if, and I 100% agree with you , Bluetooth could be turned off.

Also what is row of components between capacitors?

Thanks for your review, regards G

 

[gnat_leader]

Why don't the TPA3255 chips have the TI logo printed on them?

 

[Graham849]

Google Image Result for https://i.ebayimg.com/images/g/CMUAAOSwy0xizOXT/s-l1200.jpg

 

[gnat_leader]

Google Image Result for https://i.ebayimg.com/images/g/CMUAAOSwy0xizOXT/s-l1200.jpg

I've seen lots of similar pics to this image on Ebay. I'm not sure an online seller in Hong Kong proves anything.
Is it normal for *authentic* chips (depending on who fabricated them) to not show the TI logo?
I don't mean to cast doubts about this amp's build, I am seriously just curious about this.

 

[Pixelwarfare]

This would be a great amp if, and I 100% agree with you , Bluetooth could be turned off.

Also what is row of components between capacitors?

Thanks for your review, regards G

The row components are inductors (chokes) Typically used for output filtering

 

[nikolai]

What is the difference between "SUB OUT" and "PRE OUT" of the two amps? Is it just about having / not having the low-pass filter? I mean, would it be a good idea to connect an active subwoofer to the PRE OUT port?

 

[Pixelwarfare]

What is the difference between "SUB OUT" and "PRE OUT" of the two amps? Is it just about having / not having the low-pass filter? I mean, would it be a good idea to connect an active subwoofer to the PRE OUT port?

That’s correct, yes the full range preout can be used to connect an active sub, then adjust the low pass on the sub itself.

 

[Jacob8275]

Good review, seems the fosi are doing better.

 

[Fosi Audio]

Compared to the BT30D non-Pro (left), the Pro version is quite a bit longer and heavier (430g vs 620g).

The knobs are made of aluminium, different texture compared to the no-pro, a bit more resistance to turn. Same throw switch used to power on.

The 3.5mm PRE OUT is full range.

Bluetooth will be always-ON so your neighbour can hijack your device just like the non-pro version. Remove the antenna to prevent this from happening if you don’t use BT. Come on Fosi Audio, please fix this.

The amp has a 4” tall BT antenna, again it's better than the 7” incher of the DA2120C that looks like a CB radio... Please give us the 1 incher for future products, for once the smaller the better.

The spec in the manual is different from the official website, give us the true data!!!

BT uses an ATS2853 chip that is also found on the BL20A.

How does it sound?

I did a comparison with Onkyo RZ50 pure output mode (airplay), Aiyima T9 (BT), and the BT30D non-Pro (BT). All using RP5000F towers, with an amp selector switch.

Right away there’s a BIG difference between the non-Pro and the rest.

The Pro version is much more dynamic, the voices are clearer, bass is more present and punch harder.

I honestly cannot tell any audible difference between the RZ50 and the BT30D Pro. The T9 sounds only a tad warmer (thx lamp); Even that it was really hard to tell and it depends on the song being played.
The Pro version sounds definitely better than the non-Pro.

To test the passive sub output, I hooked up my gutted Z2300 logitech subwoofer, it works wonderfully and has a very capable output. However, I didn't like the sub crossover control, the adjustment doesn't feel linear. There are no frequency indications on the knob, it can only be tuned by ears.

Now the technical stuff:

The PCB: The board is very well built

Caps:

Relay: It does the click (barely audible) only during power on. Maybe that's why no more sparks.

The muscle: TPA3255 x 2:

PSU idle voltage: 32.3V

Power adapter output @ 8ohm load current and voltage, 125W:

Same 32V5A adapter used for multiple models. No sparks occurred while plugging in the DC plug compared to the DA2120C I've tested, I made multiple attempts to make sure this is repeatable.

Here I am trying to figure out the max usable volume before getting a bad shaped sine wave, The volume knob is at 3 o'clock, BT reference volume maxed out on my mobile device, no EQ, no tone.

L & R Channel, 8 Ohm load, 1000hz tone, 26Wrms per channel

L & R Channel, 8 Ohm load, 1000hz tone, clipping at 60Wrms

L & R Channel, 4 Ohm load, 1000hz tone, 40Wrms per channel

L & R Channel, 4 Ohm load, 1000hz tone, clipping at 100Wrms

Sub channel @ 4 Ohm load, 75Wrms:

Sub channel @ 4 Ohm load into clipping, 121Wrms:

Noise, tested with max volume:
BT30D non-Pro, audible hiss from speakers during powerup, circuit shuts off when no input signal for 5 secs to prevent constant hissing.

BT30D Pro, barely audible hiss from speakers, you have to stick your ear on the tweeter to hear it. no circuit to shut off the signal, it's not needed because it is not audible sitting away from speakers.

The TPA3255 chips are hungry AND efficient. If you can feed them, they will put out a respectable amount of power for its size. You can upgrade to a 36V power adapter if you are looking to squeeze more juice out of it. It seems most of the manufacturers using this chip have set the bottleneck to the power supply. If you are looking for a 2.1 amplifier with passive sub output, look no further.

The BT30D Pro is way better than the non-Pro version.


Pros:

• Great build quality
• Excellent sound quality, to my ear it’s on par with the Aiyima T9 and RZ50
• Low noise floor
• Runs cool and efficient

Cons:

• Cannot turn BT off
• Sub frequency needs indication and more linear tuning
• Power limited by the power supply
• 1" BT antenna plz

Thank you for testing and your great suggestions.

As per "Cannot turn BT off", we have try to add a switch to select BT or AUX like our Fosi Audio T20 does, but many people reported that the product was useless when it was received, but the fact is they didn't select the true input mode, do you have any ideas to solve this problem?

Sub frequency needs indication and more linear tuning
==> This is a great idea, we will consider it carefully.

Power limited by the power supply
==> We are developing such power supply and also consider to develop amplifiers with built in power supply to solve this issue. I will let you know once it is completed.

1" BT antenna plz
==> Also many people want a longer antenna, maybe I can provide different antennas to select.

 

[Fosi Audio]

This would be a great amp if, and I 100% agree with you , Bluetooth could be turned off.

Also what is row of components between capacitors?

Thanks for your review, regards G

Thank you, any ideas about how to solve this problem?
Because we want to keep the front panel as neat as possible. But if I add on the back panel, then many people will ignore it.

 

[Pixelwarfare]

Thank you, any ideas about how to solve this problem?
Because we want to keep the front panel as neat as possible. But if I add on the back panel, then many people will ignore it.

Use a quality double throw switch in front, OFF, RCA, BT.

 

[Graham849]

Thank you, any ideas about how to solve this problem?
Because we want to keep the front panel as neat as possible. But if I add on the back panel, then many people will ignore it.

As above, switch to select OFF, RCA, BT or OFF, BT, RCA.

If buyers cannot select correct user mode, maybe a card on top of amp with picture of instructions. We are certainly entering the digital remote/ touchscreen age when physical switch use is unfamiliar.

However, if user is capable of connecting speakers/ subwoofer I wonder why they cannot understand input selection.

Thanks again for product development and user interaction.

 

[Fosi Audio]

Use a quality double throw switch in front, OFF, RCA, BT.

Thank you for your suggestion.

 

[Fosi Audio]

As above, switch to select OFF, RCA, BT or OFF, BT, RCA.

If buyers cannot select correct user mode, maybe a card on top of amp with picture of instructions. We are certainly entering the digital remote/ touchscreen age when physical switch use is unfamiliar.

However, if user is capable of connecting speakers/ subwoofer I wonder why they cannot understand input selection.

Thanks again for product development and user interaction.

Thank you, it's really helpful, we will consider your suggestion carefully.

 

[Toku]

It is very disappointing to see that the volume pot for volume control still uses a taper B 50kΩ.
It is common sense in audio technology to use a taper A for the volume pot for volume control.
Manufacturers such as AIYIMA have gradually been modified to use Taper A.

 

[Pixelwarfare]

It is very disappointing to see that the volume pot for volume control still uses a taper B 50kΩ.
It is common sense in audio technology to use a taper A for the volume pot for volume control.
Manufacturers such as AIYIMA have gradually been modified to use Taper A.

This might also be the reason of crossover that is not linear and hard to tune.

 

[Fosi Audio]

It is very disappointing to see that the volume pot for volume control still uses a taper B 50kΩ.
It is common sense in audio technology to use a taper A for the volume pot for volume control.
Manufacturers such as AIYIMA have gradually been modified to use Taper A.

Thank you so much for pointing it out, I have forwarded to our R&D department.

 

[Kimbrough Xu]

This might also be the reason of crossover that is not linear and hard to tune.

Taper A is not linear either.

 

[Fosi Audio]

It is very disappointing to see that the volume pot for volume control still uses a taper B 50kΩ.
It is common sense in audio technology to use a taper A for the volume pot for volume control.
Manufacturers such as AIYIMA have gradually been modified to use Taper A.

Our R&D responsed Taper A will go up exponentially, and taper B will go up slowly at first and faster in the middle and will go slowly again in the end.

So do you think it is better to go up exponentially?