Fosi Audio V3 Mono Amplifier Review

[Rafaille]

I did that (went to a minidsp with Dirac from marantz with audyssey) and are now going back because in my case the AVR room correction was far superior than the minidsp.

The minidsp without room correction sounds phenomenal though, but my room is garbage.

If the minidsp sounded phenomenal (I assume you mean transparent), as expected, then it means Dirac is messing up room/speaker eq.

Unless you find your Marantz receiver more convenient in your system, if I were you I would go back to the minidsp (if you still own it) and tweak Dirac parameters. There is no reason you could not get a very similar eq compared to what Audissey does.

I would first look into limiting Dirac processing to low frequencies (say <500 Hz) and listen/measure again.

 

[Roland68]

The difference between 139W and 191W is +1.39dB

I looked at Texas and it is a full 10% more power, which corresponds to about +0.5dB.

The real reason is the possibility of connecting a 2 ohm box, because then the differences are very big.

That's the difference between numbers/theory and experience.
I had built two TPA3255 evaluation boards, 1 as a BTL, 1 as a PBTL. The headroom of the PBTL board compared to the BTL was impressive, and if more power is needed, it's a viable option.
The speakers were impedance-corrected 4 ohms and the power supply was not a limitation.
Theoretically, the difference between a Yamaha A-S 701 and 1000, for example, is not great; according to the numbers, they are even the same. In practice, hardly anyone would choose the 701 after hearing the 1000 in comparison. The performance, headroom, etc. are impressive compared to the 701.
That's the difference between theory and practice. I knew the theory beforehand, but there's no substitute for practical experience.
I can live with your opinion because I have my experience.
I think my loss is smaller.

 

[LSPhil]

That's the difference between numbers/theory and experience.
I had built two TPA3255 evaluation boards, 1 as a BTL, 1 as a PBTL. The headroom of the PBTL board compared to the BTL was impressive, and if more power is needed, it's a viable option.
The speakers were impedance-corrected 4 ohms and the power supply was not a limitation.
Theoretically, the difference between a Yamaha A-S 701 and 1000, for example, is not great; according to the numbers, they are even the same. In practice, hardly anyone would choose the 701 after hearing the 1000 in comparison. The performance, headroom, etc. are impressive compared to the 701.
That's the difference between theory and practice. I knew the theory beforehand, but there's no substitute for practical experience.
I can live with your opinion because I have my experience.
I think my loss is smaller.

OK, and here we enter the wood's space and we have no chance for a technical exchange of opinions.
I once had a small flashlight and I connected another 4.5V battery in parallel and was disappointed that it didn't shine brighter.

 

[Roland68]

OK, and here we enter the wood's space and we have no chance for a technical exchange of opinions.
I once had a small flashlight and I connected another 4.5V battery in parallel and was disappointed that it didn't shine brighter.

I don't understand the theory behind it, but you've learned something in practice.

But actually I just wanted to give you food for thought with my examples, to revise your opinion and statement and to recognize that something is wrong.
Here's the correction, because your post is also confusing other users.
Do terms like volume, sound pressure and sound intensity mean anything to you? There are a few subtle differences.

1.5 dB may not sound like much, but at 105 dB that's almost 1.5 times the volume for a human (1.4 times exactly), 3 dB would be a doubling of the volume heard.
Do you realize that 1 dB at 100 dB is an x-fold increase in the volume heard than 1 dB at 6 dB? Exactly the opposite of what is normally the case, or for example with % figures.

Of course you may think that almost 1.4 times the volume is not much, but in reality that is the difference between not being able to turn my speakers up as loud as I would like to hear and having enough headroom.

The performance tables from the data sheet are not very useful, @amirm's measurements are much more reliable, realistic, consistent and comparable.

 

[antcollinet]

The difference between 139W and 191W is +1.39dB

I looked at Texas and it is a full 10% more power, which corresponds to about +0.5dB.

The real reason is the possibility of connecting a 2 ohm box, because then the differences are very big.

I think Amir's measured difference is probably coming from all the PSU current being available for one channel, rather than split between two. And bear in mind 1.39 dB is still a 14% perceived volume increase or additional headroom.

The other advantage of the ability to drive 2ohm loads, is the capability to drive more challenging speakers - whatever the nominal impedance might be.

 

[Sokel]

I think Amir's measured difference is probably coming from all the PSU current being available for one channel, rather than split between two. And bear in mind 1.39 dB is still a 14% perceived volume increase or additional headroom.

The other advantage of the ability to drive 2ohm loads, is the capability to drive more challenging speakers - whatever the nominal impedance might be.

Based on the figures of BTL Power loss vs Output power for 4 Ohm operation and if the difference is analogous for 2 Ohm I wouldn't push it hard down there:

https://www.ti.com/lit/ds/symlink/tpa3255.pdf?ts=1717472370434&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPA3255

At 300 watt for example it will reach 70-80 watts of power loss,that's not easy to dissipate.

 

[Roland68]

I think Amir's measured difference is probably coming from all the PSU current being available for one channel, rather than split between two. And bear in mind 1.39 dB is still a 14% perceived volume increase or additional headroom.

The other advantage of the ability to drive 2ohm loads, is the capability to drive more challenging speakers - whatever the nominal impedance might be.

1.4 dB corresponds to a 40% higher volume perception for humans, 3 dB to a doubling.

The 139 watts measured by Amirm in many amplifiers in BTL operation per stereo channel and 191 watts in PBTL in mono operation is what the TPA3255 can achieve in a certain THD range. There is no limitation due to the power supply.

 

[LSPhil]

I think Amir's measured difference is probably coming from all the PSU current being available for one channel, rather than split between two. And bear in mind 1.39 dB is still a 14% perceived volume increase or additional headroom.

The other advantage of the ability to drive 2ohm loads, is the capability to drive more challenging speakers - whatever the nominal impedance might be.

14% is exactly 0.56dB. As for the ability to deal with a 2 Ohm load, I agree 100%.

 

[LSPhil]

1.4 dB corresponds to a 40% higher volume perception for humans, 3 dB to a doubling.

The 139 watts measured by Amirm in many amplifiers in BTL operation per stereo channel and 191 watts in PBTL in mono operation is what the TPA3255 can achieve in a certain THD range. There is no limitation due to the power supply.

Do an experiment and edit a recording where you increase it by +3dB. You can also take a regular audio recording and increase the volume by +3dB. If you have done that, contact me.

 

[antcollinet]

1.4 dB corresponds to a 40% higher volume perception for humans, 3 dB to a doubling.

The 139 watts measured by Amirm in many amplifiers in BTL operation per stereo channel and 191 watts in PBTL in mono operation is what the TPA3255 can achieve in a certain THD range. There is no limitation due to the power supply.

3dB is a doubling in power. That is not a doubling in perceived volume.

You need approx 10dB for a perceived doubling in volume. If you have a device with a volume control showing dB - try it.

 

[antcollinet]

14% is exactly 0.56dB. As for the ability to deal with a 2 Ohm load, I agree 100%.

Again - we are not talking about power, we are talking about perceived volume 10dB = approx doubling of perceived volume

 

[LSPhil]

Again - we are not talking about power, we are talking about perceived volume 10dB = approx doubling of perceived volume

Very good, and the difference between 100W and 1000W is exactly +10dB or 1Bel or twice as loud.

 

[LSPhil]

Based on the figures of BTL Power loss vs Output power for 4 Ohm operation and if the difference is analogous for 2 Ohm I wouldn't push it hard down there:

View attachment 373095

https://www.ti.com/lit/ds/symlink/tpa3255.pdf?ts=1717472370434&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPA3255

At 300 watt for example it will reach 70-80 watts of power loss,that's not easy to dissipate.

The diagram is about the total power of 2 channels. At 300W that would be about 60W
We remember the old light bulbs, how hot they were with 60W

 

[Sokel]

The diagram is about the total power of 2 channels. At 300W that would be about 60W
We remember the old light bulbs, how hot they were with 60W

Yep,and the diagram is for 8,6 and 4 Ohm.Extrapolating it for 2 Ohm will reach a little higher than that.

 

[LeonidKogan]

Is it known what is going to be the retail price for V3 Mono with separate 48V/5A PS? I'm within return window for dual ZA3 which I find amazing and thinking about going for V3 mono instead.

 

[JW001]

I did that (went to a minidsp with Dirac from marantz with audyssey) and are now going back because in my case the AVR room correction was far superior than the minidsp.

The minidsp without room correction sounds phenomenal though, but my room is garbage.

Without room correction, what makes it sound phenomenal?

 

[sl1982]

Is it known what is going to be the retail price for V3 Mono with separate 48V/5A PS? I'm within return window for dual ZA3 which I find amazing and thinking about going for V3 mono instead.

Working the number backwards at 980 HKD at 20% off would give you a retail of 1225 HKD. Roughly 155 USD

 

[sucramhabib]

I did that (went to a minidsp with Dirac from marantz with audyssey) and are now going back because in my case the AVR room correction was far superior than the minidsp.

The minidsp without room correction sounds phenomenal though, but my room is garbage.

Yep! I had a Minidsp with Dirac and it neutered music. It was terrible

 

[wwenze]

Turns out room reflections are nice yea?

 

[sucramhabib]

Turns out room reflections are nice yea?

Unfortunately they’re not.