Fosi Audio V3 Mono Amplifier Review

[Freezak]

C200 was an a deal quite recently, and yes I prefer it over D50 III as well, as I don't like its BT remote which goes to sleep too quickly and takes some time to wake up.
To me this is poor functionality, the C200 remote is far more responsive.
Obviously D50 III PEQ and 5v out can come to use for some, but I'd rather get a HQ headphone amp included for the price.

Unfortunately from what i see i can only find the C200 on aliexpress (i'm located in Europe), where i'd probably have to pay for some custom duties. I happen to own the DX1 headphone amp and it does the job pretty well driving my HD560s with peace apo applied. Headphone amp is a bonus obviously, but in case i want to use it, it would be pretty problematic though, having my HD560s connected to C200 and DBR62 and using both on the PC where i'd have to disable the peace apo eq whenever i use my DBR62s on my PC, thus, i guess i'd rather use headphone amp and preamp/dac separately. In this case, if C200 does not get discounted any soon, would SMSL D6s be a good enough alternative? i'm reading conflicting descriptions on whether it supports remote control or not.

 

[Bleib]

Unfortunately from what i see i can only find the C200 on aliexpress, where i'd probably have to pay for some custom duties. I happen to own the DX1 headphone amp and it does the job pretty well driving my HD560s with peace apo applied. Headphone amp is a bonus obviously, but in case i want to use it, it would be pretty problematic though, having my HD560s connected to C200 and DBR62 and using both on the PC where i'd have to disable the peace apo eq whenever i use my DBR62s on my PC, thus, i guess i'd rather use headphone amp and preamp/dac separately. In this case, if C200 does not get discounted any soon, would SMSL D6s be a good enough alternative?

Yes, or DL200 if you want a headphone amp in the same class as C200. DL200 is quite a lot bigger though.

SMSL DL200 AUDIO DAC & Headphone Amplifier MQA-CD ES9039Q2M

SMSL DL200 AUDIO DAC features MQA-CD ES9039Q2M, Bluetooth APTX HD, OPA1612 XU-316, and DSD512 compatibility, plus 6.35mm & 4.4mm headphone outputs and a handy remote control. Support MQA decoding, support MQA-CD; ESS new generation high-end digital-to-analog chip ES9039Q2M; Qualcomm latest...

hifi-express.com

Never had to pay toll or extra shipment costs through here, just make sure choose the free shipping, express can add extra costs

I bought my C200 through hificat but they have a normal price atm

 

[DavidM1]

Gotcha it's my favourite one right now - I'm guessing you've tested the Topping D50 III one or perhaps you, @DavidM1 ? it appears to have similar functionality with a slightly lower price tag, though i'm guessing only one of those will act better as a preamp combined with two Fosi V3 monos.

It’s my favourite DAC but my only other for comparison is a Cambridge Audio DacMagic that I bought more than a decade ago.

 

[Freezak]

It’s my favourite DAC but my only other for comparison is a Cambridge Audio DacMagic that I bought more than a decade ago.

Are you talking about the D50 III? thanks.

 

[DavidM1]

Are you talking about the D50 III? thanks.

Nope. Never met it. I was talking about the C200. But, as I mentioned, I’ve only had one other.

 

[gelo_mc]

Can someone with a measuring equipment confirm the phase when using rca? If out of phase, fosi should fix it

 

[JeremyFife]

Can I play back my understanding of the inverted phase issue?
With thanks for all the investigation and explanation that members have given - really helpful.

#1 Fosi amps connected as Balanced = no issue at all
#2 Fosi amps connected single-ended, no other amplifiers / active subs in the system = no practical issue

#3 Fosi amp connected single-ended but with other amps / active subs in the system = Fosi amps will be out of phase with the other amps.
In this case, solution is to invert the phase of either the Fosi amps or of the other amp.

@Fosi Audio ?

Thanks

 

[gwing]

Can I play back my understanding of the inverted phase issue?
With thanks for all the investigation and explanation that members have given - really helpful.

#1 Fosi amps connected as Balanced = no issue at all
#2 Fosi amps connected single-ended, no other amplifiers / active subs in the system = no practical issue

#3 Fosi amp connected single-ended but with other amps / active subs in the system = Fosi amps will be out of phase with the other amps.
In this case, solution is to invert the phase of either the Fosi amps or of the other amp.

@Fosi Audio ?

Thanks

Maybe I'm wrong but I don't think there is any intrinsic standard for whether amps are phase inverting or not so I would expect to have to check phase (by listening) whenever I had disparate amps in a system.

I think it's to do with amp design, each stage in an amp is generally going to invert phase so if mixing even and odd amplification stage designs you'll likely have to switch terminals for one of them. It isn't a correct or incorrect sort of thing.

Also - using the balanced inputs seems to have reversed the problem in the example given above - that could make sense as using RCA inputs goes through an extra opamp to convert to balanced so possibly there is the extra amplification stage flipping polarity. (That's just a guess, I'm not at all familiar with opamp internals and whether they count as a single or multiple stage device).

 

[JeremyFife]

Maybe I'm wrong but I don't think there is any intrinsic standard for whether amps are phase inverting or not so I would expect to have to check phase (by listening) whenever I had disparate amps in a system.

I think it's to do with amp design, each stage in an amp is generally going to invert phase so if mixing even and odd amplification stage designs you'll likely have to switch terminals for one of them. It isn't a correct or incorrect sort of thing.

Also - using the balanced inputs seems to have reversed the problem in the example given above - that could make sense as using RCA inputs goes through an extra opamp to convert to balanced so possibly there is the extra amplification stage flipping polarity. (That's just a guess, I'm not at all familiar with opamp internals and whether they count as a single or multiple stage device).

It's never simple, is it

Yes - agree.
As I understand it, using balanced connections the Fosi maintains the input signal phase. Using single-ended connections, the Fosi inverts the phase.
What that means in a system with more amplifiers/devices depends on their behaviour too.

 

[somebodyelse]

Fosi amps will be out of phase with the other amps.

Depends on the other amps. Some are inverting, others non-inverting.

 

[Bleib]

I asked Fosi about it, I have an order for 2 of them
"Hello There,
We have thoroughly tested our product at the factory before shipping, ensuring there won't be any issues. If needed, we can provide a video for you. Shall we proceed with the shipment as usual?
--
[Fosi Audio]"

 

[Sokel]

Maybe I'm wrong but I don't think there is any intrinsic standard for whether amps are phase inverting or not so I would expect to have to check phase (by listening) whenever I had disparate amps in a system.

I think it's to do with amp design, each stage in an amp is generally going to invert phase so if mixing even and odd amplification stage designs you'll likely have to switch terminals for one of them. It isn't a correct or incorrect sort of thing.

Also - using the balanced inputs seems to have reversed the problem in the example given above - that could make sense as using RCA inputs goes through an extra opamp to convert to balanced so possibly there is the extra amplification stage flipping polarity. (That's just a guess, I'm not at all familiar with opamp internals and whether they count as a single or multiple stage device).

There is (kind of) a standard and that is to output the same as input.
But regardless,even if it was an inverting amp like a few others in the past it should be on both inputs or (the proper way) none of them.

The least they should do is warn about it,imagine people running manual EQ down low filling dips (wrong,but they do) having the exact opposite effect as it's evident for example at @Miser_Audioman 's measurement.

I asked Fosi about it, I have an order for 2 of them
"Hello There,
We have thoroughly tested our product at the factory before shipping, ensuring there won't be any issues. If needed, we can provide a video for you. Shall we proceed with the shipment as usual?
--
[Fosi Audio]"

I wonder if they even know what you asked,that's not an answer by an educated engineer,probably typical PR stuff.

 

[Pecottye]

I found the phasing on the v3s to be reversed from standard, see owners thread

Thank you for this remark! I now understand why the bass was thinner than with the Edge X-300 in combination with my sub. I just inverted the speakerwires and got it back again .

 

[activewire]

It is difficult to get my head around this type of performance is such a small and inexpensive package. I have been looking to add an amplifier to my Onkyo RZ50 to drive my front speakers-ML Vistas (4 Ohm). I have no complaints with the RZ50, but the V3 Mono Blocks appear to perform better on the bench. I would be interested if people think that there would be a noticeable difference (Better or Worse) in sound quality.

I also have the RZ50 and am now building a 9 channel amp (using tpa3255 just like Fosi V3 mono see my DIY thread) for same reasons you cited.

 

[Freezak]

I have one more question - do i actually gain anything by buying two power supplies, be it 48V/5A or 48V/10A instead of one 48V/10A (+ power filter and splitter) for driving two Fosi V3 monos? they're gonna be connected to SMSL C200 or D6s and bookshelf speakers Elac DBR62. Any help would be appreciated as i have ordered the 2x Fosi V3 mono + 1x 48V/10A power filter set - i guess i could still exchange it to 2x Fosi V3 mono + 2x 48/5V as it's the same price either way - thank you!

 

[Megaken]

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...

This is not a fan - it doesn't actually cool anything down. Put your hand to it - it doesn't blow. It's an exhaust.

This one does https://acinfinity.com/component-co...nd-av-quiet-cabinet-cooling-fan-system-4-inch

 

[gelo_mc]

There is (kind of) a standard and that is to output the same as input.
But regardless,even if it was an inverting amp like a few others in the past it should be on both inputs or (the proper way) none of them.

The least they should do is warn about it,imagine people running manual EQ down low filling dips (wrong,but they do) having the exact opposite effect as it's evident for example at @Miser_Audioman 's measurement.



I wonder if they even know what you asked,that's not an answer by an educated engineer,probably typical PR stuff.

I know it is trivial just to switch the rca cables if you are aware of the issue but the problem is not all people go to forums about a product. Even if they do, can be easily buried in a long thread like this.

This is quite easy for fosi to rectify. Just swap the labels of the terminal or switch the wiring internally. They haven't acknowledge the problem though.

 

[Bleib]

OK, Fosi has now been directed to this topic through email, to the first post where it was brought up

 

[Sokel]

I know it is trivial just to switch the rca cables if you are aware of the issue but the problem is not all people go to forums about a product. Even if they do, can be easily buried in a long thread like this.

This is quite easy for fosi to rectify. Just swap the labels of the terminal or switch the wiring internally. They haven't acknowledge the problem though.

Switch the cables how?Speaker cables you mean?
Yes,but you'll have to reverse them any time you change the input.

Can't be labeled too as any labeling would be true only for the one of the two inputs.
Labeled as a warning,sure.

 

[Borland]

My V3s have also arrived
But they get very hot and I wonder when hot is too hot....

I have now ordered an infrared thermometer.

Edit:
Do they perhaps get so hot because I use 10A power supply units? Is it better to use a splitter cable and only one power supply?