Fosi Audio V3 Mono Amplifier Review

[Ordin Aryguy]

On the bright side, Texas Instruments’ specifications indicate this chip is rated for thermal operating range up to a massive 150° Celsius!

-Ed

Be careful, that 150 degree C rating from Texas Instruments is Tj. That's a measurement of Junction Temperature, which is the actual silicon encased in the chip itself.

There are many interfaces/thermal barriers between the Tj measurement point and the case of the Fosi Mono can and will not effectively move heat energy.

edit - added 2nd line.

 

[PJ_Schmidt]

the thermistor you are referring to is this:

View attachment 377293

I'm pretty sure they're using the big resistors in conjunction with the NTC thermistor for inrush limiting. I suspect the white relay is used to bypass the inrush protection once the bulk capacitors are near full voltage.

 

[EddNog]

Be careful, that 150 degree C rating from Texas Instruments is Tj. That's a measurement of Junction Temperature, which is the actual silicon encased in the chip itself.

Good thing I have no intention of pushing this thing anywhere near its real limits.

 

[MCH]

I'm pretty sure they're using the big resistors in conjunction with the NTC thermistor for inrush limiting. I suspect the white relay is used to bypass the inrush protection once the bulk capacitors are near full voltage.

Agree with the relay, one of the contacts bypasses the thermistor, the second connect the output to the speaker terminals. Regarding the resistors, I cannot be 100% as this is the only picture of the new version I have, but I would be surprised if they are not the zobel network. Will see, I am very curious.
Edit: looking at how they are placed, you might be riy. Maybe they needed to bring the SMD resistors somewhere else because they wouldn't fit anymore.... hmm, interesting
Nah, it can't be! Bah, I don't know, but I want to find out hahah

 

[PJ_Schmidt]

Agree with the relay, one of the contacts bypasses the thermistor, the second connect the output to the speaker terminals. Regarding the resistors, I cannot be 100% as this is the only picture of the new version I have, but I would be surprised if they are not the zobel network. Will see, I am very curious.
Edit: looking at how they are placed, you might be riy. Maybe they needed to bring the SMD resistors somewhere else because they wouldn't fit anymore.... hmm, interesting
Nah, it can't be! Bah, I don't know, but I want to find out hahah

The picture is hard to read, so I thought it looked like both big resistors are in parallel and connected to the power jack, but I might be wrong. Being a Zobel network is a solid alternative. Considering Erin's Audio Corner fried one of his units doing test tones, it is not impossible to imagine one of those small SMD resistors were part of the Zobel network and overheated after an extended period.

 

[Jtabos]

Hi there from Portugal!
For those concerned about the shipping arrival, my V3 monos (2 x 48v 5a) just arrived and quickly joined their new partners: Wiim Mini - Fiio Br13 dac - Heco Aurora 300's - active Sub Jamo C910 and AC Infinity fans.

(Also came with two extra opamps).
They have replaced a Fosi Bt20a Pro (48v 5a), and so far, I'm happy with the upgrade.
Probably, I'll replace the Mini and the Fiio for the Wiim Ultra, just for the sub out and the room correction features, thou I don't really have complains about the room, because this is an (one side) open space; speaking of that, it's very common here to go higher than 40 C (104 F), so the fans were very useful to prevent the Bt20a Pro from reaching "melting temperatures".

I'd like to thank you all for the great information I've found in this forum that helped me to build this system.
Best regards
Juan

 

[EddNog]

Hi there from Portugal!
For those concerned about the shipping arrival, my V3 monos (2 x 48v 5a) just arrived and quickly joined their new partners: Wiim Mini - Fiio Br13 dac - Heco Aurora 300's - active Sub Jamo C910 and AC Infinity fans.
View attachment 377302
(Also came with two extra opamps).
They have replaced a Fosi Bt20a Pro (48v 5a), and so far, I'm happy with the upgrade.
Probably, I'll replace the Mini and the Fiio for the Wiim Ultra, just for the sub out and the room correction features, thou I don't really have complains about the room, because this is an (one side) open space; speaking of that, it's very common here to go higher than 40 C (104 F), so the fans were very useful to prevent the Bt20a Pro from reaching "melting temperatures".
View attachment 377303
I'd like to thank you all for the great information I've found in this forum that helped me to build this system.
Best regards
Juan

Hey for $12 per unit, these are not bad at all!

MULTIFAN S1, Quiet USB Cooling Fan, 80mm

Your source to create smart growing systems with components including advance grow tents, inline fans, clip-on fans, LED grow lights, and UIS™ controllers.

acinfinity.com

-Ed

 

[Jtabos]

Hey for $12 per unit, these are not bad at all!

MULTIFAN S1, Quiet USB Cooling Fan, 80mm

Your source to create smart growing systems with components including advance grow tents, inline fans, clip-on fans, LED grow lights, and UIS™ controllers.

acinfinity.com

-Ed

Indeed, but I bought the dual version on amz.es for 40eur!

Later I've found other brand that sells a similar 80mm duals just for 14 eur...

 

[Keauval]

Hi there from Portugal!
For those concerned about the shipping arrival, my V3 monos (2 x 48v 5a) just arrived and quickly joined their new partners: Wiim Mini - Fiio Br13 dac - Heco Aurora 300's - active Sub Jamo C910 and AC Infinity fans.
View attachment 377302
(Also came with two extra opamps).
They have replaced a Fosi Bt20a Pro (48v 5a), and so far, I'm happy with the upgrade.
Probably, I'll replace the Mini and the Fiio for the Wiim Ultra, just for the sub out and the room correction features, thou I don't really have complains about the room, because this is an (one side) open space; speaking of that, it's very common here to go higher than 40 C (104 F), so the fans were very useful to prevent the Bt20a Pro from reaching "melting temperatures".
View attachment 377303
I'd like to thank you all for the great information I've found in this forum that helped me to build this system.
Best regards
Juan

Hi, how is the sound compared to BT20A Pro please ?
Thanks

 

[GoDawgs]

Hey for $12 per unit, these are not bad at all!

AC Infinity makes great gear, I've gotten some of their other thermostats and fan systems for other hobbies. You can see the quality in the equipment they sell.

 

[EddNog]

AC Infinity makes great gear, I've gotten some of their other thermostats and fan systems for other hobbies. You can see the quality in the equipment they sell.

Other…hobbies…definitely the theme of YouTube reviews of their products LOL

 

[Miser_Audioman]

At least I received a standard text from Fosi via Kickstarter today
Better than nothing ...


"Hi, Our team is working diligently to ensure that your order is completed and dispatched by the end of this month at the latest. We are committed to providing you with the highest quality product and service, and we appreciate your understanding as we work to fulfill your order as quickly as possible.

Thank you once again for your patience and understanding. If you have any further questions or concerns, please do not hesitate to reach out to us.

Warm regards,
Fosi Audio Team"

Ah crap, well it seems i have a lot of suffering ahead. I can’t believe I have to keep listening to my HK avr for another couple months. Tragic, as I’m sure these are going to make a HUGE improvement to my sound quality. Youtube said as much lol…

 

[rgpit]

Has anyone from the USA received their V3 Mono or at least a notification of shipment? It seems all of the shipments have been going to the Asian or European markets.

 

[DavidMcRoy]

Has anyone from the USA received their V3 Mono or at least a notification of shipment? It seems all of the shipments have been going to the Asian or European markets.

I'm in (the State of) Washington, USA and got an email today with an estimated June 2024 delivery, but also requesting a shipping address verification. I don't think it'll make it here by the end of this month if they're just now asking for address verification.

 

[EddNog]

Has anyone from the USA received their V3 Mono or at least a notification of shipment? It seems all of the shipments have been going to the Asian or European markets.

I have my pair and have been listening since yesterday. I love them, and am extremely pleased with upgrading to them from the pair of ZA3s I had prior.

-Ed

EDIT: PS I’m in New Jersey.

 

[PJ_Schmidt]

Has anyone from the USA received their V3 Mono or at least a notification of shipment? It seems all of the shipments have been going to the Asian or European markets.

I'm in MN and the tracking I received last week shows delivery in two days (Thursday)

 

[Negatywny]

still nothing for me. I'm starting to feel a little anxious

 

[Nuigurumi]

Received them yesterday.
Great little amps and smaller than I thought. As mentioned before, they do get hot.
Using them to drive 'refurbished' Diatone DS77Z's.

 

[Borland]

Has anyone already received 48V 10A versions or only 5A?

I believe that Fosi has delivery problems with the 10A versions ...

 

[Negatywny]

for me it looks like equal problems with delivering the 5A power bricks also...