Fosi Audio BT20A Pro Amplifier Review

[grogi.giant]

Its a pre out, and for audiophiles it should be chinch. This 3.5mm stereos are garbadge. At least this is my experience in the last 40 years. This 2$ would not change much. And having a long time reliable connection is worth a lot.

A true audiophile will never look at TRS or even RCA connectors, as only balanced connection (exp. XLR) preserves the signal. /s

Check out how much less space it is using than double RCA. I'd rather have three 3.5mm stereo inputs than one RCA TBH. TRS might be not as durable, especially on the receptacle side, but once the plug is in, it is equally good.

 

[312elements]

This v3 looks nice, lets see whats the price?

Any guesses? Given the superior case/cooling, name brand components, etc, it’s going to cost more. The kickstarter, to me implies this is a small batch run that’s outside of the core business so that may be reflected in price also. I think we’re looking at 2x the price here.

If this were on Amazon, I’d order 2 right now. The kickstarter thing is a huge turnoff to me personally.

 

[tomtoo]

A true audiophile will never look at TRS or even RCA connectors, as only balanced connection (exp. XLR) preserves the signal.

TRS might be not as durable, especially on the receptacle side, but once in it is equally good.

I not liked to start a discussion about balanced or unbalanced. There are thousends out there. Just like to say that 3.5 mm stereo is the most unreliable connector you can use.

 

[tomtoo]

Any guesses? Given the superior case/cooling, name brand components, etc, it’s going to cost more. The kickstarter, to me implies this is a small batch run that’s outside of the core business so that may be reflected in price also. I think we’re looking at 2x the price here.

If this were on Amazon, I’d order 2 right now. The kickstarter thing is a huge turnoff to me personally.

Mhh, no more tone controlle. No more BT. So maybe 50% or less up?

 

[312elements]

Mhh, no more tone controlle. No more BT. So maybe 50% or less up?

Good points. I think that this would be a real victory at 1.5x the cost of the BT20A. I’m sure we’ll find out soon enough.

 

[grogi.giant]

I not liked to start a discussion about balanced or unbalanced. There are thousends out there. Just like to say that 3.5 mm stereo is the most unreliable connector you can use.

I guess without /s it is difficult to sense the sarcastic tone... Sorry

 

[tomtoo]

I guess without /s it is difficult to sense the sarcastic tone... Sorry

Sry, no sarcasm. ,my english is maybe the same worse than a 3.5mm stereo trs.
Some time it works, some time not so well.

Btw, there is enough room on the back side of this amp. And besides the reliability it would also look much better. I cant take 3.5mm as serious connectors.

 

[Talisman]

I don't understand the enthusiasm.
same chip, same power supply, no bluetooth and no tone controls.
If eliminating the tone controls also means no load dependency then ok, that's an added value, but we have no way of knowing without measurements.
The only thing they have done that can be deduced is to solve a non-problem, present only in the minds of some audiophiles, by drilling holes in the case for more dissipation which may not be necessary.

 

[312elements]

I don't understand the enthusiasm.
same chip, same power supply, no bluetooth and no tone controls.
If eliminating the tone controls also means no load dependency then ok, that's an added value, but we have no way of knowing without measurements.
The only thing they have done that can be deduced is to solve a non-problem, present only in the minds of some audiophiles, by drilling holes in the case for more dissipation which may not be necessary.

They didn't just drill holes in the top of the case, they made the entire case a heat sink which if nothing else decreases the operating temperature of the unit and by association the components themselves. The previous models appeared to be built to meet a specific price point. The newer components are better built components with longer lifespans and tighter tolerances. I know better than to suggest that it could possibly sound better, but it would stand to reason that it would last longer. It's entirely plausible that it could measure better as well, though the measured gains would likely be inaudible. If none of those things interest you, that's totally fine, but I commend the company for creating a 3255 implementation that is different from what others are doing.

 

[Talisman]

They didn't just drill holes in the top of the case, they made the entire case a heat sink which if nothing else decreases the operating temperature of the unit and by association the components themselves. The previous models appeared to be built to meet a specific price point. The newer components are better built components with longer lifespans and tighter tolerances. I know better than to suggest that it could possibly sound better, but it would stand to reason that it would last longer. It's entirely plausible that it could measure better as well, though the measured gains would likely be inaudible. If none of those things interest you, that's totally fine, but I commend the company for creating a 3255 implementation that is different from what others are doing.

I got to congratulate the company in the best way for a company. I bought two bt20a pro, I had already bought a T20 and a T3.
I congratulate Fosi by opening my portfolio to their products which I find exceptional in price/performance ratio and very well cared for compared to competitors in that price range.
But none of the Fosi products that I own and have also used extensively have ever failed, even in very small cases, so again, why insist on solving a non-problem?
At the moment this version, as far as we know, responds more to a marketing need, in satisfying some users who would feel reassured by greater heat dissipation which at the moment does not seem justified by overheating problems of any Fosi unit. my acquaintance.
If beyond this the measurements will also show good benefits in terms of audio quality then it will be a different matter, but at the moment we don't know it (nor should we assume it)

 

[312elements]

I got to congratulate the company in the best way for a company. I bought two bt20a pro, I had already bought a T20 and a T3.
I congratulate Fosi by opening my portfolio to their products which I find exceptional in price/performance ratio and very well cared for compared to competitors in that price range.
But none of the Fosi products that I own and have also used extensively have ever failed, even in very small cases, so again, why insist on solving a non-problem?
At the moment this version, as far as we know, responds more to a marketing need, in satisfying some users who would feel reassured by greater heat dissipation which at the moment does not seem justified by overheating problems of any Fosi unit. my acquaintance.
If beyond this the measurements will also show good benefits in terms of audio quality then it will be a different matter, but at the moment we don't know it (nor should we assume it)

Rather than drive this conversation in an unproductive direction, I think that this product just isn't for you. I think this product is about more than dissipating heat, but to stay on that topic I think with harder to drive speakers and 48V power supplies the thermal limitations of the 3255 are being pushed close to their maximum. With a 48V power supply and LS50's, if I run one unit for each channel (not bridged) the case of the unit runs relatively cool. If I hook up both speakers to one unit then the case gets hot to the touch. Conversely, when I hook up two L82 Classics to one amp it stays relatively cool and when I use the 32V instead of the 48V power supply I can do whatever I want and it really doesn't get very hot. If you're not concerned about the heat, don't buy it. If yours doesn't get hot in your setup, be happy. The folks at Fosi are listening and I encourage you to vote with your wallet as I'm sure you will. Better cooling, components with tighter tolerances and longer lifespans. This is exactly what I was hoping would happen with increased competition.

 

[Joe Smith]

I agree, nice new option for people who want to drive these smaller amps to higher power levels/sound levels. Good components. $140-150 a good price point for it? The ideal unit for me would also have at least two RCA inputs and the ability to switch between them. But this is definitely going in a good direction. I'd probably opt for an SMSL A300, or a Hypex-based amp, instead of this right now for my higher power needs, but I applaud Fosi for continuing to offer options.

 

[Fosi Audio]

@Fosi Audio


View attachment 280002

This is from Fosi product page, needs correction - inaccurate description/details.

Our silly mistake.
Just revised it.

 

[Guddu]

@Fosi Audio
Found answer to PSU query, Product page says "Power Supply: 32V/5A, 48V/5A". Wondering why not 36v?
Also, any interest towards balanced design? and/or dual input?

What‘s in the box？
1. V3 ×1
2. User Manual × 1
3. 32V/5A or 48V/5A Power Supply × 1

 

[Jimi Floyd]

I received yesterday my Fosi BT20A Pro with the 32V power supply and I have it connected to a pair of Klipsch Cornwall speakers. It is amusing to hear this very small and very light amplifier push two giant speakers with their 15" woofers to loud sound levels.

Anyway, using the RCA input or the Bluetooth input does not give the same sound quality, the Bluetooth being brighter. In wireless mode I am comfortable dialing 60° counterclockwise the treble knob. Out of curiosity I decided to measure the frequency response of both input modes. I don't have refined lab equipment. As a signal generator I used a MacBook pro running Audacity, set to produce sine tones, 31 in total, spaced by 1/3 octave. The computer was connected to the amp 1) through a Topping D10s DAC and RCA cables to the RCA input, and then 2) via Bluetooth. The amp was connected to the speakers and the output voltage of the right channel was measured by a multimeter for each frequency. 0dB was set at 2V amplifier output (1 kHz).

RCA input

More or less flat, with a rise in the treble reaching +2dB at 20 kHz. My ears arrive to 12-13 kHz, so I hear a +1dB rise at most, that is perfectly tolerable. Amir measured a +0.5 dB rise at 20 kHz with a 8 ohm load. I don't know the high frequency impedance of the Klipsch Cornwall, It may be higher than 8 ohm or have a phase different from 0, that would explain the difference.

Bluetooth input

I didn't expect this result. Bass frequencies are rolled off below 63 Hz, then there is a minimum at 315 Hz, then a rise up to almost +3dB at 10 kHz followed by a drop at 20 kHz. Now I understand why the sound feels light and bright with Bluetooth. I googled "Bluetooth audio frequency response" but I could not find any single plot, so that I don't know if all Bluetooth devices have this problem or it is codec related or it is just my amp. I hope somebody here can help me to better understand what is going on.

 

[Fosi Audio]

@Fosi Audio
Found answer to PSU query, Product page says "Power Supply: 32V/5A, 48V/5A". Wondering why not 36v?
Also, any interest towards balanced design? and/or dual input?

What‘s in the box？
1. V3 ×1
2. User Manual × 1
3. 32V/5A or 48V/5A Power Supply × 1

1. Yes, we'll provide 32V/5A and 48V/5A PSU. Do you think a 36V one is necessary?
2. We're developing an amp with a balanced design and dual inputs. It will be out there in the following few months.

 

[Fosi Audio]

I agree, nice new option for people who want to drive these smaller amps to higher power levels/sound levels. Good components. $140-150 a good price point for it? The ideal unit for me would also have at least two RCA inputs and the ability to switch between them. But this is definitely going in a good direction. I'd probably opt for an SMSL A300, or a Hypex-based amp, instead of this right now for my higher power needs, but I applaud Fosi for continuing to offer options.

I'd like to disclose that the price of the V3 is far less than what you expected.

 

[asnow]

I'd like to disclose that the price of the V3 is far less than what you expected.

I'm getting BT20A Pro buyer's remorse.... Maybe you'll give a coupon code to the BT20A Pro supporters

 

[Fosi Audio]

I'm getting BT20A Pro buyer's remorse.... Maybe you'll give a coupon code to the BT20A Pro supporters

No problem.

 

[Guddu]

1. Yes, we'll provide 32V/5A and 48V/5A PSU. Do you think a 36V one is necessary?
2. We're developing an amp with a balanced design and dual inputs. It will be out there in the following few months.

My query was more around any known issue with using 36v psu, rather than necessity.
I have used 32v/36v/48v with other manufacturer’s tpa3255 amps and observed more heating with 48v even on lower volume (6 ohm load), but had no issues using 36v.
I am not suggesting it might be similar with your product.