Fosi Audio V3 Amplifier Review

[Bobemeg]

If I touch the case of the amplifier, there is no more noise. Video 2 google drive.
Should I use it like this or ask for a replacement... I just got it from aliexpress... It will take some time and I don't want it.

 

[OldTimer]

If I touch the case of the amplifier, there is no more noise. Video 2 google drive.
Should I use it like this or ask for a replacement... I just got it from aliexpress... It will take some time and I don't want it.

why don’t you try to change the rca cable first? then check the speaker’s banana plug to the amp.
I’m using the rca to rca from line out of my integrated amp, not using 3.5mm to rca.

After I add the V3 amp to the stack (not using the class A/B amplification from the integrated amp because no speakers connected to it), electricity reduced by 50% and sound increased by 100%. Very helpful.

 

[Bobemeg]

It can be heard without the rca cable connected.

 

[OldTimer]

It can be heard without the rca cable connected.

can be defected unit.

Regarding your hand touch the amp, it means that your body become the ground of the amp.

 

[antcollinet]

If I touch the case of the amplifier, there is no more noise. Video 2 google drive.
Should I use it like this or ask for a replacement... I just got it from aliexpress... It will take some time and I don't want it.

This sounds more like a system grounding problem rather than a problem with the amp.

Are any of the components in your system grounded?

 

[Citizen]

One of my 48v(5amp) power supplies died today, plugged it in(connected to the amp but amp not switched on) and it made three popping noises and now does not work, anyone else have any issues with there PSU?

 

[guy48065]

A class D PSU feeding a class D amp. What could go wrong?
My experience with switch-mode power supplies has not been good. Apparently everyone loves them because they're everywhere now, and getting cheaper all the time (as are replacements for failed...).

I've been very impressed with my V3 and wondering where to go from here.
Has anyone tested one of these amps with a linear supply? Or a higher current SMPS? I've read one review of the V3 powered from a 48V 6A supply but the comparison was to the 36V PSU. How would it behave with 10A on tap?

Does more current = more control with this type amp?
I haven't seen a spec or even a mention of Damping Factor. Is that because it goes out the window after chopping/boosting/smoothing?

 

[antcollinet]

How would it behave with 10A on tap?

Probably no differently.

I haven't seen a spec or even a mention of Damping Factor. Is that because it goes out the window after chopping/boosting/smoothing?

No, it is because it is high enough on practically all modern solid state amps for it to no longer be an issue.

 

[Falcon91]

Hi i recently got my V3 and bought their 48V power supply but the amp feel weak in the low end even connected to easy to drive speakers. Is this normal and does anyone else have similar problems. The speakers i tried are old Wharfedale Diamond III at 8Ohm and Philips MCM 906 at 4Ohm both sub 100W speakers and i have to be at 60%+ to get the low end.

 

[antcollinet]

Hi i recently got my V3 and bought their 48V power supply but the amp feel weak in the low end even connected to easy to drive speakers. Is this normal and does anyone else have similar problems. The speakers i tried are old Wharfedale Diamond III at 8Ohm and Philips MCM 906 at 4Ohm both sub 100W speakers and i have to be at 60%+ to get the low end.

No, not normal - and it is almost certainly not the amp.

Most likely speaker/room interaction. Though it is possible the amp lacks power for the size of your room/listening distance. But that would be the case for any amp of similar power.

If you are comparing with another amp under identical conditions, make sure you have accurately level matched.

 

[Falcon91]

No, not normal - and it is almost certainly not the amp.

Most likely speaker/room interaction. Though it is possible the amp lacks power for the size of your room/listening distance. But that would be the case for any amp of similar power.

If you are comparing with another amp under identical conditions, make sure you have accurately level matched.

Its in a small room and its near field listening on a desktop i was using old Nakamichi SR-4E receiver rated at 60W and i never used it on more than 50% otherwise the speakers would blow and now with the V3 i can use them them on more than 70% at still be comfortable so im thinking there is problem with the V3 maybe the caps or the amp chip i tried different power supplies one from Fosi and one from MeanWell 48V at 21A.

 

[mike70]

Maybe ... maybe ... Now you're listening to a flat and clean sound.
Valve amplifiers have the same effect, 30 watts on valves "feels like" transistors at 100 watts, but it's only bloated bass and distortion.

 

[Falcon91]

Maybe ... maybe ... Now you're listening to a flat and clean sound.
Valve amplifiers have the same effect, 30 watts on valves "feels like" transistors at 100 watts, but it's only bloated bass and distortion.

My Nakamichi SR-4E is in really good condition and its considered a high quality receiver in the audio community because its a Nelson Pass design and i have tested it with tons of speakers on the same playlist so im 100% sure it sounds decent. Im not expecting the Fosi V3 to be the same but the difference is massive the low end is just not there.

 

[antcollinet]

Its in a small room and its near field listening on a desktop i was using old Nakamichi SR-4E receiver rated at 60W and i never used it on more than 50% otherwise the speakers would blow and now with the V3 i can use them them on more than 70% at still be comfortable so im thinking there is problem with the V3 maybe the caps or the amp chip i tried different power supplies one from Fosi and one from MeanWell 48V at 21A.

Don't pay any attention to the volume control position - it depends also on the amp gain. It may be that the Nakamichi just has higher gain (not power) than the V3, resulting in it needing a lower setting on the volume control for the same power, and possibly reaching full power long before the full turn of the dial.

What is the output voltage of the source?

You are comparing two amps, so you need to accurately level match at the speaker terminals with a meter.

 

[Falcon91]

Don't pay any attention to the volume control position - it depends also on the amp gain. It may be that the Nakamichi just has higher gain (not power) than the V3, resulting in it needing a lower setting on the volume control for the same power, and possibly reaching full power long before the full turn of the dial.

What is the output voltage of the source?

I haven't measured it but i use a Topping D10s DAC for everything. I will take it apart and measure the capacitors if everything checks out i will try with different settings to see what happens.

 

[antcollinet]

I haven't measured it but i use a Topping D10s DAC for everything. I will take it apart and measure the capacitors if everything checks out i will try with different settings to see what happens.

You don't need to measure anything - just check the specifications. Measuring any capacitors wouldn't answer the question in any case.


EDIT : It has a 2V output.

EDIT some more : your Nakamichi amp has an input sensitivity of 200mV (full power at 0.2V input with volume at max). Which is why you are turning the volume dial so far down. The DAC is giving it 10x the voltage it needs.

The FOSI needs about 6 times that for full power, so the volume control needs to be higher.

This is why you need to level match with a volt meter, and not with a volume control.

 

[Sokel]

Analog volume pots have been scratchy since time immortal. Turn the amp off, unplug it, then twist the volume from off to max volume ten times quickly. This usually clears the wipers and makes the problem go away for a while. Some people also spray electronics contact cleaner into the pot.

You mean crappy analog pots obviously (and I mean completely crappy).
Also the wrong analog pots for the application.
What the heck,we use them in mic pre-amps all the time,think about that.

 

[OldTimer]

Actually the normal volume is at 20-30%. It’s already suck the woofer of the speaker.
I’m doing it to 60-90% everyday 10 hours per day non stop for 1 month, just want to find any defect in the amp. Now I’m back to 35% volume enjoying music from $80 amp.

 

[Falcon91]

You don't need to measure anything - just check the specifications. Measuring any capacitors wouldn't answer the question in any case.


EDIT : It has a 2V output.

EDIT some more : your Nakamichi amp has an input sensitivity of 200mV (full power at 0.2V input with volume at max). Which is why you are turning the volume dial so far down. The DAC is giving it 10x the voltage it needs.

The FOSI needs about 6 times that for full power, so the volume control needs to be higher.

This is why you need to level match with a volt meter, and not with a volume control.

Ok i get it now i will have to tune my system to make the best of the V3.

 

[OldTimer]

This is the speaker connection:

it’s 6 ohm floorstanding speakers. Bi-wiring it to the amp parallel become 3 ohm. The V3 will be even happier if it’s 2 ohm.