Fosi Audio V3 Amplifier Review

[nathan]

That’s called the Clever Hans Effect.

Clever Hans - Wikipedia

en.wikipedia.org

 

[Lux_ury]

Well Hans told me the horse could talk especially when sugar was involved.

 

[antcollinet]

Nope I send people who can hear better than me run a few tests at the same levels ask which they liked run the same tests without changes to check if they think I've changed something then use that to determine which they preferred.
one friend is literally blind I trust her ears more than mine.
I have fun testing peoples perception of bias, but some tests are night and day no matter what volume is set. Don't get me wrong I love science methodology, but you know what....... you like what you like

Fair enough - but failure to level match invalidates the blindness of the testing. You've given the listener an easy cue to dectect differences which are not about the quality of the sound - but never the less are perceived as a quality difference.

If you are interested in carrying out blind testing that has some validity See:
Audio Blind Testing - You Are Doing It Wrong!

 

[Lux_ury]

Fair enough - but failure to level match invalidates the blindness of the testing. You've given the listener an easy cue to dectect differences which are not about the quality of the sound - but never the less are perceived as a quality difference.

If you are interested in carrying out blind testing that has some validity See:
Audio Blind Testing - You Are Doing It Wrong!

Hi Ant I appreciate the flow of traffic and the response and ASR has the equipment to test analytical data that I love, takes out the costly work to be done. Sometimes sitting having a beer listening to what you like is what's it's all about. I listen to cheap equipment to appreciate the better ones, sometimes my perspective gets reset. My post on the A07 highlights somepeople prefer different products made by different manufacturers as do I. My equipment is decade's old and mixing a lesser quality unit sometimes yields better results.
By the way the pots are different which is why usually I set one at 9.00 the other 12.00.

 

[antcollinet]

Hi Ant I appreciate the flow of traffic and the response and ASR has the equipment to test analytical data that I love, takes out the costly work to be done. Sometimes sitting having a beer listening to what you like is what's it's all about. I listen to cheap equipment to appreciate the better ones, sometimes my perspective gets reset. My post on the A07 highlights somepeople prefer different products made by different manufacturers as do I. My equipment is decade's old and mixing a lesser quality unit sometimes yields better results.
By the way the pots are different which is why usually I set one at 9.00 the other 12.00.

Hi.... err.... Lux?

All that is fine, when it is for your own enjoyment.

What we struggle with a little here though is people offering advice to others on what to do or buy, based only on their own subjective impressions. Not only is it likely to lead the other person down an incorrect path (their subjective perception will likely be different from yours - especially when the objective performance of the devices in question is near identical), but it also reinforces the incorrect (especially when related to electronics) view that when evaluating gear - uncontrolled listening is the way to do it.

There is already too much of that in the rest of the audio world. We don't need it here also.

 

[mike70]

And ... everyone have the right to listen / buy what they want. Ok.

But I (and many others here) want the truth. I mean, we want to pay the right amount for the right audio component.

You only get that with an objective perspective, see the class D implementations under 1k with better power / audio quality than many (many) classic class AB brands with 4 / 5k price tag.

If you don't care, it's ok, is your money ... but I want to invest to the right thing.

And that's all.

 

[Dreyfus]

Does anyone know how much input voltage the V3 can handle without clipping?

Push.

 

[olieb]

Does anyone know how much input voltage the V3 can handle without clipping?

Amir measured 190W into 4Ω with 48V PSU. That is about 27.5Vrms output voltage.
Gain was measured at 26.4dB, so the amp amplifies voltage by a factor 20.9
I assume the measurement was with volume pot at max.
So clipping with 48V PSU will only happen with at least 1.31Vrms input (or more depending on the volume control).

EDIT: On the other hand you need a source with at least 1.3Vrms to drive the amp to full power. So older gear with line levels in the 200-500mV range are not a good fit.

 

[nathan]

Amir measured 190W into 4Ω with 48V PSU. That is about 27.5Vrms output voltage.
Gain was measured at 26.4dB, so the amp amplifies voltage by a factor 20.9
I assume the measurement was with volume pot at max.
So clipping with 48V PSU will only happen with at least 1.31Vrms input (or more depending on the volume control).

That's interesting. Near as I can tell, my AVR line outs can possibly go as high as 5vrms, so I better be careful and NOT turn up the V3 (with 48v power supply) pot to max.

Now, I need to figure out a method to decide just how much to turn up the v3 volume control.

 

[antcollinet]

Amir measured 190W into 4Ω with 48V PSU. That is about 27.5Vrms output voltage.
Gain was measured at 26.4dB, so the amp amplifies voltage by a factor 20.9
I assume the measurement was with volume pot at max.
So clipping with 48V PSU will only happen with at least 1.31Vrms input (or more depending on the volume control).

EDIT: On the other hand you need a source with at least 1.3Vrms to drive the amp to full power. So older gear with line levels in the 200-500mV range are not a good fit.

I suspect @Dreyfus is interested in clipping at the input stage (normally related to the power rail voltage of the input stage). So if the volume is turned down such that the amp doesn't clip. How much input voltage can be applied to the amp without the input stage being driven to rails.

I've not found a spec for this, nor is it measured.

I would guess it is not normally an issue, for anything up to normal balanced line voltages of 5V or so. But it is not possible to be definitive.

 

[Dreyfus]

@antcollinet
Indeed, I was referring to the input stage.
My DAC is an EX5 with 2.1V of line level. I was just asking since I'd like to know how much of the volume range in percent I can effectively utilize to control the total volume of the chain without driving the amp input into clipping. The pot of the V3 itself would stay fixed since I prefer the remote of my DAC to control both headphones and speakers.

 

[antcollinet]

@antcollinet
Indeed, I was referring to the input stage.
My DAC is an EX5 with 2.1V of line level. I was just asking since I'd like to know how much of the volume range in percent I can effectively utilize to control the total volume of the chain without driving the amp input into clipping. The pot of the V3 itself would stay fixed since I prefer the remote of my DAC to control both headphones and speakers.

Well unless FOSI wanted to make their amp incompatible with 50%+ of sources, including pretty much all CD players, they will be able to accommodate 2V with significant headroom.

I'd normally expect at least 10V because why would a desig engineer restrict it? They have to provide a low voltage supply for the input electronics and there is no advantage to a supply low enough to cause problems.

 

[olieb]

I suspect @Dreyfus is interested in clipping at the input stage

Yeah, I thought about that too, but this is not measured because nobody cares. It is not a problem.
Probably the input pot just attenuates the input signal, so there is no practical limit for input voltage.
If not, the input stage op-amps are probably driven with about ±15V and input voltage of 5 or 7 Vrms should not be a problem. Unless you use a power amp of course, then you might overdrive the input at full volume.

 

[PlasticDoc]

Someone pointed to me this:
Fosi Audio V3 2024 Version: https://fosiaudio.com/pages/v3-2024-version

Lets see, what changes were implemented in V3 to enhance buyer satisfaction and value?

Did they add PFFB? No.
Did they add a separate power switch (i.e. a switch not integrated into the volume)? No.
Did they add better thermal coupling between the TPA3255 chip and the amplifier case? No.
Did they add better components? No.

Well, what have they added to justify the "V3 2024 version" status? The former pre-out is now controlled by the V3's power switch and volume.

Note to @Fosi Audio:

• For a company to be successful, it needs both innovation and marketing.
• Although Fosi is already known for its agressive marketing, innovation is still a crucial factor.
• When it comes to innovation (i.e., something new that brings satisfaction and value for the customer), it's important to avoid lazy engineering. Unfortunately, this has caused the downfall of many manufacturers, not just in the audio equipment industry.

 

[Bobemeg]

In fact they only fixed what was wrong the first time. Nothing wow.

 

[Talisman]

Someone pointed to me this:
Fosi Audio V3 2024 Version: https://fosiaudio.com/pages/v3-2024-version

Lets see, what changes were implemented in V3 to enhance buyer satisfaction and value?

Did they add PFFB? No.
Did they add a separate power switch (i.e. a switch not integrated into the volume)? No.
Did they add better thermal coupling between the TPA3255 chip and the amplifier case? No.
Did they add better components? No.

Well, what have they added to justify the "V3 2024 version" status? The former pre-out is now controlled by the V3's power switch and volume.

Fantastic Fosi, what an improvement! They really listened to what people wanted.

Take note @Fosi Audio:

• For a company to be successful, it needs both innovation and marketing.
• Although Fosi is already known for its agressive marketing, innovation is still a crucial factor.
• When it comes to innovation (i.e., something new that brings satisfaction and value for the customer), it's important to avoid lazy engineering. Unfortunately, this has caused the downfall of many manufacturers, not just in the audio equipment industry.

How many other products do you know of that have been improved in an updated version to integrate a user request?
It's true that we are never satisfied.
There are other Fosi products for other needs, others will be released. This is just a corrected version of an already excellent product, I WISH there were many companies with this attention to the customer

 

[antcollinet]

Someone pointed to me this:
Fosi Audio V3 2024 Version: https://fosiaudio.com/pages/v3-2024-version

Lets see, what changes were implemented in V3 to enhance buyer satisfaction and value?

Did they add PFFB? No.
Did they add a separate power switch (i.e. a switch not integrated into the volume)? No.
Did they add better thermal coupling between the TPA3255 chip and the amplifier case? No.
Did they add better components? No.

Well, what have they added to justify the "V3 2024 version" status? The former pre-out is now controlled by the V3's power switch and volume.

Fantastic Fosi, what an improvement! They really listened to what people wanted.

Take note @Fosi Audio:

• For a company to be successful, it needs both innovation and marketing.
• Although Fosi is already known for its agressive marketing, innovation is still a crucial factor.
• When it comes to innovation (i.e., something new that brings satisfaction and value for the customer), it's important to avoid lazy engineering. Unfortunately, this has caused the downfall of many manufacturers, not just in the audio equipment industry.

Don't make the mistake of thinking that something unimportant to you is not important to someone else. There were many complaints about the pre-out not being volume controlled, because it is useless for a Sub.

PFFB would almost certainly be a new model, not a version change..
Power switch? Not an issue for me - though I accept it might be for you.
Last two - are they remotely needed? I've heard of no overheating issues, nor particular problems from the selected components. Further - I'd never market such changes as they would suggest the previous version was somehow lacking quality.

 

[mike70]

Someone pointed to me this:
Fosi Audio V3 2024 Version: https://fosiaudio.com/pages/v3-2024-version

Lets see, what changes were implemented in V3 to enhance buyer satisfaction and value?

Did they add PFFB? No.
Did they add a separate power switch (i.e. a switch not integrated into the volume)? No.
Did they add better thermal coupling between the TPA3255 chip and the amplifier case? No.
Did they add better components? No.

Well, what have they added to justify the "V3 2024 version" status? The former pre-out is now controlled by the V3's power switch and volume.

Fantastic Fosi, what an improvement! They really listened to what people wanted.

Take note @Fosi Audio:

• For a company to be successful, it needs both innovation and marketing.
• Although Fosi is already known for its agressive marketing, innovation is still a crucial factor.
• When it comes to innovation (i.e., something new that brings satisfaction and value for the customer), it's important to avoid lazy engineering. Unfortunately, this has caused the downfall of many manufacturers, not just in the audio equipment industry.

I think you need other amplifier, not an upgrade based on the objective features / price that Fosi have with V3.

PFFB is for other target / price tag product, for sure.

 

[nathan]

I think you need other amplifier, not an upgrade based on the objective features / price that Fosi have with V3.

PFFB is for other target / price tag product, for sure.

True. I would love a product like this:

PFFB, internal power supply, a 12v triggered power on switch

But it would be silly to expect it to still be called the V3 and at the $100 price point. Such a change would merit a whole new product model number, and perhaps price point.

(Alas Fosi didn't do that with their new amp on kickstarter, either, which I agree really is a missed opportunity.)

 

[PlasticDoc]

PFFB, internal power supply, a 12v triggered power on switch

1. Regarding PFFB: page 4 (Table 1. Recommended PFFB Component Values) of the TI TPA325x Spec sheet, shows how cost-effective it is to add PFFB to a TPA3255. With only 11 components, most of which cost only a few cents each, the additional cost to the final product would be around 10 to 15€. This would put the V3 closer to the 3e audio TPA3255 260-2-29A Amplifier.

2. The added cost of PFFB would be even lower if using the so called "differentiating postfilter" (which is just a single 100pF capacitor that connects loudspeaker out to audio in, as described in the post "TPA3255 oscillation issues" at diyaudio.com). This one would cost a few cents only.