Fosi Audio BT20A Pro - Opinions and Comparisons

[anthony 5]

I have this model, rich sound the volume pot looks a little loose, and when closing amp because of two potentiometers will have a slight clicking sound coming from speakers fosi said this was normal

 

[Kegemusha]

It seems there is a newer version?

Fosi Audio BT30D

 

[Jeromeof]

It seems there is a newer version?

Fosi Audio BT30D

I don't think that is a newer version - that has a different amp chipset.

 

[Jeromeof]

Spotted someone has opened this up model and replaced the op-amps . Looks pretty easy to do:

 

[Talisman]

Now available in Europe on Amazon

 

[Jeromeof]

I see @amirm reviewed this and recommended it:

Fosi Audio BT20A Pro Amplifier Review

This is a review and detailed measurements of the Fosi Audio BT20A stereo class D amplifier based on TI TPA3255 IC. It was sent to me by the company and costs US $99.99 with 32 volt power supply. Despite its low cost, the case gives a feeling of quality. I am not usually fan of tone controls in...

www.audiosciencereview.com

 

[2fatpugs]

Hi, can someone clarify how the pre-out works? I currently have the Aiyima A07 but the one thing that annoys me about it is that it passes the pre-out signal to my subwoofer even with the power off. This means when I am using my headphones the sub is still playing. Anyone know if the BT20A Pro does the same thing?

Thanks!

 

[Jeromeof]

Hi, can someone clarify how the pre-out works? I currently have the Aiyima A07 but the one thing that annoys me about it is that it passes the pre-out signal to my subwoofer even with the power off. This means when I am using my headphones the sub is still playing. Anyone know if the BT20A Pro does the same thing?

Thanks!

I hadn't noticed but I can check in the next few days. I would have thought if either device is switched off no audio would be passed through the pre-out but I will check the BT20a pro.

 

[375HP2482]

I have been using the A07 for a year, great amp. Add this one and these seem to be the definitive desktop/bedroom amplifiers for bookshelf systems.

 

[Jeromeof]

Hi, can someone clarify how the pre-out works? I currently have the Aiyima A07 but the one thing that annoys me about it is that it passes the pre-out signal to my subwoofer even with the power off. This means when I am using my headphones the sub is still playing. Anyone know if the BT20A Pro does the same thing?

Thanks!

Ok, sorry for the delay in getting back, just got back to testing out the BT20A pro today but I can confirm that the BT20A pro does actually send on the RCA input signal to when its it is powered off, so it will have the same 'problem' in that your subwoofer will get the signal even if the BT20A pro is switched off.

I imagine this is possible a feature for some people but I agree with an active subwoofer this is not ideal.

 

[MiniAudioGuy]

Spotted someone has opened this up model and replaced the op-amps . Looks pretty easy to do:

Anyone know why the Ayima A07 and Fosi Audio BT20A Pro have 2 x dual op amp sockets?

With my Burson Funk one is for the input buffer and one is for the Headphone Amp Voltage Gain Stage.

For single ended RCA inputs/outputs, shouldn't a single dual op amp be able to handle both left and right channels?

 

[Kimbrough Xu]

Anyone know why the Ayima A07 and Fosi Audio BT20A Pro have 2 x dual op amp sockets?

With my Burson Funk one is for the input buffer and one is for the Headphone Amp Voltage Gain Stage.

For single ended RCA inputs/outputs, shouldn't a single dual op amp be able to handle both left and right channels?

They are for left and right channels.

 

[375HP2482]

The amplifier chip is actually four discrete amplifier blocks that individually use buffer/voltage amplifiers.

In these units the four amp blocks are used in pairs for bridge (BTL) operation.

 

[2fatpugs]

Ok, sorry for the delay in getting back, just got back to testing out the BT20A pro today but I can confirm that the BT20A pro does actually send on the RCA input signal to when its it is powered off, so it will have the same 'problem' in that your subwoofer will get the signal even if the BT20A pro is switched off.

I imagine this is possible a feature for some people but I agree with an active subwoofer this is not ideal.

Thanks for letting me know. I'll skip on the BT20A Pro.

 

[Fishfan]

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.

Hi, I having d supplied 32v 5A power brick. Thinking of upgrading to 36v 6A. Is this a upgrade and worth it? Not considering 48v because my place is hot.

 

[312elements]

Hi, I having d supplied 32v 5A power brick. Thinking of upgrading to 36v 6A. Is this a upgrade and worth it? Not considering 48v because my place is hot.

I think that's about a 35% increase in power. Ultimately depends on how loud you like to listen and how efficient your speakers are. If you're not backing off of the volume knob over distortion issues now, it's probably not worth the upgrade.

 

[mhardy6647]

"35% increase in power" = 1.3 dB

 

[312elements]

"35% increase in power" = 1.3 dB

I’m admittedly out of my element here. Would that be close to 10% louder?

 

[mhardy6647]

I’m admittedly out of my element here. Would that be close to 10% louder?

Barely detectable in terms of loudness.
It could make a difference in terms of the somewhat ephemeral realm of "headroom" (i.e., accurate reproduction of dynamics) but in terms of volume/loudness, nada.

 

[Clmrt]

If anyone has a link or model number for the hotter power supply I'd appreciate it.