Fosi Audio V3
I wanted to share with you another of my passions and one of those little diamonds that sometimes break into the audio market.
The Fosi Audio V3 is a little gem that doesn't need much light to shine.
What is it about?
From a minimalist amplifier from the company
Fosi Audio, a brand that for some years now has been positioning itself as a reference in a market range that did not exist before.
HI-FI has historically been inaccessible to the general public.
Fosi is offering products with a high level of quality at a very competitive price that allow you to enjoy quality sound at a reasonable cost.
A great advantage of globalisation and new communication channels is that the customer/brand relationship has changed radically. In this case, the FOSI brand listens to its customers and takes their opinions into account in the product development phase.
Something unthinkable a few years ago and that changes the rules of the game, the client no longer buys what a brand has designed according to their ideas, the client is part of the project.
What does the FOSI V3 have to offer?
Minismalism
In a very compact enclosure measuring 105x143x40 mm there is a well thought-out selection of components which show their full potential in the sound test.
Large selection of components
The minimalist design features a front panel with an operation indicator LED and a volume adjustment dial with a very good feel and a silent connection - "there is no expected connection noise/pop".
There is no remote control and I don't think it is necessary, if you use it as a desktop amplifier it is within reach and if it is a remote installation, remember your old school days without this accessory.
The rear is still minimalistic, with RCA signal input connectors, speaker output with screw/banana plugs and a 3.5 mm stereo output with fixed signal level independent of the front fader.
Fosi indicates in future revisions of the device that it will be variable depending on the front-end controller.
For this test I have two V3 units, a 32V and a 48V version.
It is the same device where only the PSU varies, the 48V PSU is larger than the V3.
The listening tests were carried out with HECO VICTA PRIME 302 loudspeakers and a S.M.S.L DO300 DAC.
Two configurations
Configuration 1 - One V3 unit in normal connection mode
Configuration 2 - Bi-wiring mode with two V3 units (32V-48V)
The sound tests
Component preparation
PSU (Power Supply Unit) Comparative
Tests in bi-amplification mode
Adjusting audio levels and format
Wait a minute, where is the secret camera? How is it possible to obtain this power with these micro dimensions?
Declared power
These are the declared maximum power ratings, in the range of 20 to 20000 hz and with Thd < 1% they are lower but sufficient to drive any box on the market with quality.
Depending on the installation, we have a power of 60 to 100 watts per effective channel.
The Heco 302s offer a sensitivity of 90 dB 8 Ω - (2.8V/1M) and during tests with the 32 V and 48 V versions they perform well.
The potentiometer offers a logarithmic curve in its operation, this allows a more precise adjustment when using a lower volume, it may seem strange to you but it is a feature commonly used in professional audio.
The hated but necessary connecting cables
So 32 V or 48 V? It all depends on the set and the power you usually use.
If you want quality sound at low volume, the 32 V version is sufficient.
Is your installation demanding? Use 48v
The sound is balanced and there is no background noise. You can position the instruments in front of you and the timbre is completely neutral.
This sound will always depend on the speakers you use in your installation. The V3 is only a neutral link in the sound chain, it does not colour the signal.
For the V3, Fosi offers the possibility to replace the standard NE5532 operational amplifiers.
The V3 is compatible with a variety of dual 8-pin op-amps such as Sparkos SS3602, MUSES02, OPA2604, OPA2134PA, OP249, AD827, RM4559, LM4562, LME49720HA.
This level of customisation allows the user to easily modify the personality of the amplifier.
Across different musical styles, from classical, pop, rock to techno, the V3 shows no fatigue or distortion.
The Texas Instruments TPA3255 chip does an exceptional job, during testing and using bass-heavy techno music the external temperature of the V3 did not exceed 40ºC with a start-up temperature of 30ºC.
(Spain, August 2023, in the middle of a heat wave).
Bi-amp & crossover mode
In the bi-amplification tests I used the 32V version to feed the treble and the 48V version.
Changes?
This results in an improvement in sound clarity, an improvement in detail as more dynamics are available to work with the loudspeaker.
In future tests I will perform a signal filtering prior to V3 to assign a frequency range to each V3.
The usual version on the market is the 32V version (32V/5A external power supply), although there is also a 48V/5A power supply version and a V3 only version without power supply, different options for different equipment. This, together with the possibility of customising the device, makes it a very useful component in the usual jigsaw puzzle that is high-end sound equipment.
Conclusions
A must-have component in primary, secondary and desktop systems.
Pros
Quality of construction
Value for money
Power module performance
Possibility to customise operational amplifiers
Cons
Remote control? May be necessary in some cases
Unregulated pre-output output.
In the same case as the remote control, a large majority of users do not use this function.
Specifications
Max Power Output: 300Wx2 @4Ω
SINAD: ≥88dB
SNR: ≥110dB
Terminating Impedance: 2-8Ω
THD: <0.003%
THD: <0.003%
THD: <0.003% THD
: <0.003
Power Amp: TI TPA3255
Op-Amp: TI NE5532 x2
Power Supply: 32V/5A, 48V/5A
Power Input Range: DC 24V-48V
Frequency Response Range: 20Hz-20kHz(±0.1dB)
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