Fosi Audio BT30D Pro review

[Fosi Audio]

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.

We did take into account this problem and we have developed a brand new model BT20A Pro, which has the function to clear unknown Bluetooth connections if you find your amplifier hijacked.

 

[plenus]

Lurking for a few months here and Fosi has my respect and money, they truly listen to feedback and work to improve their products, and that is very respectable. Good job, can't wait for my BT30D Pro to arrive and rock hard my JBL's.

 

[Honu]

What's your centre speaker?

A old Jamo center speaker

 

[jamjam]

A old Jamo center speaker

I still don't get it.

You have "BT30D => FR, FR (FL?) and Sub (active or passive)" and "Directing 2 back channels to the TB10D => RR, RL" By my count, that's 4.1. What amp does the centre channel signal go to?

 

[theronic]

We did take into account this problem and we have developed a brand new model BT20A Pro, which has the function to clear unknown Bluetooth connections if you find your amplifier hijacked.

Instead of having to clear unwanted connections, consider letting users hold down a button to enable Bluetooth pairing mode so that intruders can't connect in the first place, i.e. treat the cause, not the symptom. This is how all other Bluetooth devices like JBL speakers do it.

 

[Fosi Audio]

Instead of having to clear unwanted connections, consider letting users hold down a button to enable Bluetooth pairing mode so that intruders can't connect in the first place, i.e. treat the cause, not the symptom. This is how all other Bluetooth devices like JBL speakers do it.

Yes, I understand what you mean. In fact, our team had a brainstorming session about whether or not to include a mode selector. Ultimately, we concluded that if a customer is looking for an amplifier with Bluetooth connectivity, Bluetooth is likely to be their preferred option for playing music. Therefore, Bluetooth connection should take priority over the RCA connection, and the user shouldn't need to select it. Nonetheless, we understand that many people still prefer having a mode selector. Therefore, we plan to create a new model in the future that will meet this demand.

 

[theronic]

Yes, I understand what you mean. In fact, our team had a brainstorming session about whether or not to include a mode selector. Ultimately, we concluded that if a customer is looking for an amplifier with Bluetooth connectivity, Bluetooth is likely to be their preferred option for playing music. Therefore, Bluetooth connection should take priority over the RCA connection, and the user shouldn't need to select it. Nonetheless, we understand that many people still prefer having a mode selector. Therefore, we plan to create a new model in the future that will meet this demand.

The issue is not that the default mode is Bluetooth - that's fine. The issue is that your Bluetooth mode allows unknown or malicious devices to connect and override the currently connected Bluetooth device, i.e. to pair without enabling Pairing. So the distinction is whether pairing with new devices is enabled or not. I don't want my neighbour to connect to my device unless I enabled Pairing Mode. But I want all previous N devices who have been authorized to be able to connect at any time.

 

[SWSL]

Really appreciate the review. I cannot, see the images on this post. They are all broken and changing browser/connections does not fix that. Is there something that can be done? Thank you!

 

[Kimbrough Xu]

The issue is not that the default mode is Bluetooth - that's fine. The issue is that your Bluetooth mode allows unknown or malicious devices to connect and override the currently connected Bluetooth device, i.e. to pair without enabling Pairing. So the distinction is whether pairing with new devices is enabled or not. I don't want my neighbour to connect to my device unless I enabled Pairing Mode. But I want all previous N devices who have been authorized to be able to connect at any time.

Maybe a password can solve the problem.

 

[kiranmatrixlee]

What is the maximum RMS watts I can get from Fosi Audio BT30D PRO . I check with customer care and they told 165W x2+350W@4Ω is PMPO. The actual is 105W x2+100W@4Ω RMS with provided power supply. I can see TPA3255 can provide more than double the RMS that customer care told us.

Can I connect JBL GT-X 1200 JBL 1200W(300W RMS) subwoofer to the amplifier and make remarkable output to an average size room?

 

[Kimbrough Xu]

What is the maximum RMS watts I can get from Fosi Audio BT30D PRO . I check with customer care and they told 165W x2+350W@4Ω is PMPO. The actual is 105W x2+100W@4Ω RMS with provided power supply. I can see TPA3255 can provide more than double the RMS that customer care told us.

Can I connect JBL GT-X 1200 JBL 1200W(300W RMS) subwoofer to the amplifier and make remarkable output to an average size room?

Just do it!

 

[kiranmatrixlee]

Just do it!

I am planning to buy one. But having some confusion.
My requirement is to connect the below speakers

Left and Right speaker specs
Model: Sony SS-VX333
Watts: 120 W RMS
Impedance: 6Ohm
Type: 3Way

Subwoofer specs
Model: JBL GT-X 1200 JBL
Watts: 300W RMS (1200W PMPO)
Impedance: 4Ohm


I contacted Fosi Audio and with this spec, I need to buy a Subwoofer amp too. One expert from Youtube told that connecting this subwoofer will damage the amp. So I am a little bit confused.

 

[JoelMercier]

I just received this amplifier from Amazon. I've got a question regarding the subwoofer frequency adjustment: It doesn't seem to change the frequencies sent to the mains, is this normal? I would much prefer unloading deep bass from the mains.

The floorstanders I am currently testing the BT-30D with don't require a sub because they can play down to 26hz, though I bought this little amp for a bedroom setup to pair with two 3" tang band fullranges and a 6" tang band subwoofer. I don't want deep bass sent to the fullranges...

There's also a fair amount of noise coming out of the midrange when the volume pot is at max and treble half way. My speakers are dead silent with my main amp.

Edit: the noise doesn't change with the treble adjustment at all. I would describe the noise as a duck doing Morse codes. Super weird....I tried moving the power supply further way with no change.

 

[Kimbrough Xu]

I am planning to buy one. But having some confusion.
My requirement is to connect the below speakers

Left and Right speaker specs
Model: Sony SS-VX333
Watts: 120 W RMS
Impedance: 6Ohm
Type: 3Way

Subwoofer specs
Model: JBL GT-X 1200 JBL
Watts: 300W RMS (1200W PMPO)
Impedance: 4Ohm


I contacted Fosi Audio and with this spec, I need to buy a Subwoofer amp too. One expert from Youtube told that connecting this subwoofer will damage the amp. So I am a little bit confused.

Why does this subwoofer will damage the amp?

 

[Kimbrough Xu]

I am planning to buy one. But having some confusion.
My requirement is to connect the below speakers

Left and Right speaker specs
Model: Sony SS-VX333
Watts: 120 W RMS
Impedance: 6Ohm
Type: 3Way

Subwoofer specs
Model: JBL GT-X 1200 JBL
Watts: 300W RMS (1200W PMPO)
Impedance: 4Ohm


I contacted Fosi Audio and with this spec, I need to buy a Subwoofer amp too. One expert from Youtube told that connecting this subwoofer will damage the amp. So I am a little bit confused.

I would prefer use a BT30D PRO to power your speakers and subwoofer together, though you may not get the max power from your setups, but for an average size room, I think it's enough.

 

[kiranmatrixlee]

Why does this subwoofer will damage the amp?

One YouTuber who bought this told me.

 

[SWSL]

I have been communicating with Fosi about ventilation for this unit as we had a scare during a party where the sound dropped way down and it had to rest before it would play again, which then repeated. I suspected it was actually a power brownout not the amp and it appears that was the problem as the amp has performed well at several more dance parties since. Though we now point a 6" fan onto the amp case to be sure. I am interested in finding out if some passive ventilation would be a good idea and also wanted to hear from Fosi what the limit for an improved power supply would be with some ventilation holes in the case. Fosi has been very helpful but at some point, the person helping me changed and became less so. They would not confirm if the 36V voltage limits were due to ventilation or components. Well, they sorta said, "both".

BUT, looking over the specifications, I found that while Fosiaudioshop.com (where I bought it) sells this as a TPA3255 amp, the manual for the amp lists it as a 3251 based product. I then found the TI marketing info for the 52xx series - TI New audio amplifiers - showing that the 3251 IS a lower output chip than the 3255 so now the 36V limit makes sense. It's the amp's limit because it's not using 3255s. The TPA3255 has an 18-53.5V PS range while the TPA3251 has a 12-36V PS range.

So, it's good to know what these amps are actually built with, especially since they are misrepresented on the product page. Still a great amp, but not what I thought I was buying. On the product page, they advertise a 5255 based amp with specifications of a 5255 but that seems to be false given the voltage limit and the chip specified in the user manual.
Product page - Claims dual TPA3255
User manual - Describes as TPA3251

Cheers

 

[JoelMercier]

Good to know.
There's also the stock power supply that's 32v 5A, so given the around 90% efficiency, the real power as shipped is somewhere in the 140W ballpark total.

It's still plenty enough for my needs, though that kind of advertising is lame...

 

[SWSL]

Good to know.
There's also the stock power supply that's 32v 5A, so given the around 90% efficiency, the real power as shipped is somewhere in the 140W ballpark total.

It's still plenty enough for my needs, though that kind of advertising is lame...

The 3255 and the 3251 are pin compatible so Fosi may have designed it for one and then sourced the other. Not that this is fair to the buyer like me who believed their product page's info. I did believe them that I was buying a 3255 amp.

 

[Bohnster]

I asked this in the other Fosi Pro thread and will delete which ever one doesn't receive a response first. ;-)

I've got a weird question. (3-Channel Setup)

I'm sure someone knows the answer to this. Could you make a three channel set up with this? Right channel goes to right speaker. Left channel goes to left speaker. And then the positive of left and right go to positive of a center channel positive, while you select either the left or right channel negative for the negative? I know in some amplifiers, connecting the positives of the amplifier can like, blow them up. I'm just curious if this could be done and have it not blow, up assuming you keep it within its volume limits.

Texas Instruments TPA3255EVM evaluation board

This link shows a TPA3255 evaluation board, and on page 18 they start showing schematics. May not be the exact same setup, but maybe this would show someone who knows what's going on, if that's possible.