Fosi Audio BT30D PRO TPA3255 "Subjective review"

[Aaronb1138]

Can I connect a passive speaker (to be used as center) to the passive subwoofer output terminal? Can I still hook up my active sub using the pre-out if I do this? I am trying to create a 3.1 set-up using the BT-30D Pro amp. Thanks!!

Get 2 and have a 4.2 setup.... Or a Fosi V3 and BT30D Pro for a 4.1.

But in all seriousness, what is your source? You need a multichannel AVR, multichannel decoder, or PC / RPi to get a true Center channel. Of those a PC is usually the best bang for the buck by way of NUC form factor stuff with high SNR audio codec hardware or external soundcards.

 

[mx2]

For folks that have the amp - can you confirm if the power connector is feels a touch loose (the one to connect the brick to the wall?). While it connects and plays nicely, it feels like any movement or jolt will disconnect it.

@Fosi Audio can you confirm which treble / bass setting I should set for neutral sound?

 

[WinWiz]

What power brick do you have? My 36V is about as loose as most other power bricks.

Treble and bass in middle position should give you neutral sound. But high-frequency output varies a bit with speaker impedance. So if your speakers are 4 ohm you might have to adjust the treble down.
Your room also affects the sound so I suggest that you adjust for your personal preference.

 

[mx2]

What power brick do you have? My 36V is about as loose as most other power bricks.

Treble and bass in middle position should give you neutral sound. But high-frequency output varies a bit with speaker impedance. So if your speakers are 4 ohm you might have to adjust the treble down.
Your room also affects the sound so I suggest that you adjust for your personal preference.

It's a 32V Fosi branded AC adapter. I can usually dangle the PSU by holding the cord - not even close in this case. Looks like it's mostly the cord though (seems normal when I use a cord for another PSU). Not exactly confidence inspiring if you ask me LOL.

Thanks for confirming the positions! My preference changes depending on the music / time of day LOL

 

[elksoith]

Hi @Fosi Audio I just purchased the amp and wondering what are the values for the output caps, the big smds near the binding posts? I saw the inside picture of V3 and it uses red caps instead of smds near the binding posts, I'm guessing they have the same value? I'm planning to replace the caps of the BT30D pro

Btw, may I ask why the regular BT30D uses LM 324? Are they used in signal path? And if they do in signal path, are they being configured to act as class A? Because LM 324 is not commonly used as opamps...

I also own the regular BT30D

 

[Gensonic]

Es una pregunta porque no 48v. Ya hice y me contestaron x los capacitores pero no parece. Yo sigo con la idea que la verdad es porque los estan vendiendo con 3251 y no 3255. O tal vez estoy equivocado. Hubo fotos de adentro sin "heatsink" pero no los puedo ver. De todos modos es chip de calidad y con una fuente de 36 v x 10 a va a rendir muy muy bien. Rinde bastante bien con su fuente de 32v x5 a que tengo ahora. Tambien puedo comentar que si quiere ventilacion extra si lo vas utilizar con volumen alto.

While exploring through the threads and videos on Fosi BT30D Pro, I came across a YouTube video exposing the presence of 2 pcs of TPA3255 chip, not 3251.

TPA3255 Chip #1

TPA3255 Chip #2

Video credit:

 

[john11]

Amir gave the previous model the BT20A a score of 83, as there is no amir review of the BT30D pro roughly what kind of score would you give
I hear that once you get to a score of 85 it is difficult to tell much difference between amps, do you think this is correct

 

[grogi.giant]

Amir gave the previous model the BT20A a score of 83, as there is no amir review of the BT30D pro roughly what kind of score would you give
I hear that once you get to a score of 85 it is difficult to tell much difference between amps, do you think this is correct

You're focusing on the SINAD too much. It is not an overall score, but one of many components that makes a good amplifier.

I would argue that there are a few that are more important and audible than a difference between 80 and 90dB in SINAD.

 

[SWSL]

While exploring through the threads and videos on Fosi BT30D Pro, I came across a YouTube video exposing the presence of 2 pcs of TPA3255 chip, not 3251.

TPA3255 Chip #1
View attachment 337592

TPA3255 Chip #2

View attachment 337593

Video credit:

I was the one who suggested the 3251 might be the reason for the voltage spec that matches that one better than the 3255. Anyway, it's effectively the same, whether it's the chip or something else in the circuit that limits the max voltage. But happy to know that my hypothesis is proven wrong!

When I pulled my heat sink I could not see any writing, just black.

 

[john11]

You're focusing on the SINAD too much. It is not an overall score, but one of many components that makes a good amplifier.

I would argue that there are a few that are more important and audible than a difference between 80 and 90dB in SINAD.

Okay, to put it anoher way reading amir's review for the BT20A, he seems fairly positive. I am wondering how much of an improvement the BT30D is

 

[grogi.giant]

Okay, to put it anoher way reading amir's review for the BT20A, he seems fairly positive. I am wondering how much of an improvement the BT30D is

It isn't an improvement/evolution. It just adds another amplifier for subwoofer, plus a few filters.

With high probability it performs worse than recent stereo amps from Fosi. More interference, shared power supply etc.