2 x Fosi V3 + 2 x 10A 48V psu - what the hell?

[dcolak]

This post is going to bring a ton of hate. Never the less, here it goes:

NAD M51 -> XLR -> 2 x Fosi V3 + 2 x 10A 48V psu's -> JBL Array 1400 -> Harsh male vocals, no bass, at all, unnatural sounding, just something resembling bass, very strange.

NAD M51 -> XLR -> 2 x TOPPING LA 90 Discrete bridge mode -> Whoa -> Bass is back, blooming, no harshness in vocals, everything holographic.

TOPPING D50III -> XLR -> 2 x Fosi V3 + 2 x 10A 48V psu -> Wharfedale Elysian 4 -> no dynamic range at all -> volume at -10dB -> it all sounds horribly flat and unnatural.

TOPPING D50III -> XLR -> Yamaha p3500s -> Wharfedale Elysian 4 -> dynamic range is back, sound quality is back, much more holographic and "natural."

If those Fosi's have 100W RMS into 8ohm I'm going to eat my hat. Those things are no hi-fi.

What in the world people?! Is everything today shill?

Why didn't anyone mention that the speaker connectors are so small and of such a bad quality?

One of connectors lost its plastic "cup" on the first use.

The speaker cables those can accept are of the thinnest ones you can imagine.

My old Dayens Ampino amp with 25W RMS into 8 ohms moves the speakers with more authority and much more finesse than two Fosi V3s.

What is most surprising is the sound that Fosi v3 produces, it sounds unnatural, suffocated.

I am a big fan of old Trends TA-10 amplifiers, those were pushing (and still do) my big JBL's with a wonderful sound.

What is this Fosi v3 nonsense? Sounds horrible, after watching and reading all "reviews" I thought they were good amps.

They sound horrible with all these speakers: JBL Array 1400, Wharfedale Elysian 4, JBL S38II, JBL S312II, Klipsch RB81.

 

[Somafunk]

Why didn't anyone mention that the speaker connectors are so small and of such a bad quality?

One of connectors lost its plastic "cup" on the first use.

Can’t help with anything else as I don’t own/have no need for the V3 but why not use banana plugs on the speaker connection?

 

[dcolak]

Can’t help with anything else as I don’t own/have no need for the V3 but why not use banana plugs on the speaker connection?

Did not want to put one more connector in-between, never saw such a small hole for the cable.

 

[DVDdoug]

The only thing that would make sense is if the Fosi having less gain making it quieter unless you turn it up higher, and if the input signal is too low you might not be able to get full power even at maximum volume. (And that would mean you're not clipping.)

You shouldn't get "weak bass" or "harsh vocals". I simply can't explain those...



FYI - Dynamics is the difference between the loud and quiet parts. Of course the loudness is limited by power but if you're not clipping the dynamic range or "dynamic contrast" is from the recording , not the amplifier. Clipping is a very-bad kind of dynamic compression.

When we talk about the dynamic range of an amplifier it's the difference between the noise floor and the maximum output. The dynamic range of amplifier is generally higher than the program material. If "dynamic range" of an amplifier is a problem it's usually noise in the background which is heard as noise and doesn't affect the program dynamics... It's just annoying during quiet or silent parts. Technically, it could be clipping but that's usually heard as distortion rather than a loss of dynamics.

 

[TurtlePaul]

Are you doing volume matched comparisons? The Fosi v3 Mono has much less gain than some of those other amps. If you are accustomed to what ‘-10 dB’ in your setup sounds like, the Fosi may need to be at -4dB to have the same volume.

I suspect that your critique couldn’t survive a blond volume matched comparison, but I don’t know if you can arrange that.

 

[dcolak]

You are right about the dynamic range of the amp. Maybe the better description is "I keep feeding it more volume, up to -10dB and less" and instead of getting louder sound, with pronounced differences between less loud and more loud parts of the song, I get everything mushed into something that doesn't sound loud and is not pleasant to ears."

I've experienced something similar with low power amps.

I used TOPPING D50III with both 4V and 5V output.

Switching to my PA Yamaha p3500s made speakers wake up with same -10dB input from the DAC, speakers started moving as you'd expect it.

Same goes for Topping LA90 Discrete in bridge mode, no complaints there.

Harsh male voices -> one of the songs that I noticed that on was in album Le Ceneri di Heliodoro by Rome, song Uropia o Morte.

I was thinking "hey, why is his voice so harsh and metalic" and "maybe other amps are bad and hid the fact his voice was harsh?"

I don't think that's the case, my other amps (NAD M3, may it rest in peace, included) are transparent and good sounding.

 

[dcolak]

Are you doing volume matched comparisons? The Fosi v3 Mono has much less gain than some of those other amps. If you are accustomed to what ‘-10 dB’ in your setup sounds like, the Fosi may need to be at -4dB to have the same volume.

I suspect that your critique couldn’t survive a blond volume matched comparison, but I don’t know if you can arrange that.

You might be right, I didn't do volume matching. I'll try matching volume and see what happens.

 

[MaxwellsEq]

What is most surprising is the sound that Fosi v3 produces, it sounds unnatural, suffocated

When making comparisons, you MUST ensure you have level-matched the voltage at the speaker terminals to be within 0.01V using an AC voltmeter. Otherwise, sighted audio comparisons of amplifiers are a waste of time.

It's also essential you understand the difference between gain and power. A 1200W power amplifier with 2dB of gain will sound a lot quieter (all other things being equal and at normal listening levels) than a 30W amplifier with 35dB of gain.

 

[telemike]

Have you played with the input gain switches on the V3's? I was using a pair for a while and I never noticed these issues with my Klipsch Forte IV.

 

[staticV3]

You might be right, I didn't do volume matching. I'll try matching volume and see what happens.

As a basic control to make sure what you're hearing is real, simply record the same track using both chains, load the recordings into Pkane Deltawave, and use the built-in Comparator to see if you can still differentiate after Deltawave has matched timing and loudness.

The microphone must be fixed in place so that the playback chain is the only variable.

 

[JohnnyNG]

My V3 Mono (with "only" a 5A supply each) unsurprizingly sound great powering my Revel M106, even compared to the previous Purifi 1ET400A. Both transparent.

I do agree on the binding posts. They are indefensibly cheap and thin. I have other inexpensive amps like the Topping PA5 and Sabaj A20a but these are in an underclass of their own.

 

[dcolak]

As a basic control to make sure what you're hearing is real, simply record the same track using both chains, load the recordings into Pkane Deltawave, and use the built-in Comparator to see if you can still differentiate after Deltawave has matched timing and loudness.

The microphone must be fixed in place so that the playback chain is the only variable.

I'll be back with measurements

 

[dcolak]

Can't believe how bad are Fosi's with bass. There is no bass. It's like turning on a high pass filter.

Playing tones through Audacity shows that is not true, these speakers go strong to 36Hz, and I can clearly hear them with Fosi's.

But, play music and all the bloom, all the room nodes disappear, it's just, dry, unnoticeable, "non-existing" bass. Music becomes boring, non-enticing.

Are all d-class amps like that? Voices sound almost "metalic," nothing sounds natural.

I misplaced my microphone, I'll record the same song Fosi V3 vs Dayens Ampino, as soon as I find it.

 

[staticV3]

Remember: microphone position must be identical for both recordings, so mount it on a tripod or similar.

 

[olds1959special]

Am I allowed to say it? Change the op-amps!

 

[xanalog]

@dcolak,
Think of constructing your own speaker cables as a pleasure this hobby allows you.
It's rather therapeutic!

Am I allowed to say it? Change the op-amps!

Only if you area masochist!

 

[Lefteris]

I’m extremely disappointed with the support I received from Fosi Audio. When their product failed, they took an unreasonably long time to respond, and ultimately refused to stand behind what they sold. Despite clear evidence of the issue, they dismissed their responsibility and offered a token $30 as compensation — a gesture that felt more like an attempt to silence the complaint than to resolve it.


What’s most concerning is their disregard for basic consumer rights. Rather than addressing the problem or offering a meaningful solution, they chose to deflect and delay. This experience has left me with no confidence in their customer service or their commitment to quality.


I would strongly caution others to consider this before purchasing. A company that doesn’t support its own products is not one I can recommend.

 

[xanalog]

A company that doesn’t support its own products is not one I can recommend.

I think of the lot of DACs -and other audio hardware I purchased from FOSI/SMSL/Topping/Douk- strictly as consumable audio hardware.
Yes, I keep my fingers crossed that they don't fail but if they do; none of them are worth my time to try (in vain) to get compensated.

[ymmw but me thinx, this is the least stressful way.]

 

[Peter_P]

IME these amps sound a lot better with MUSES02 op-amps which lean warm. Maybe you should try them before abandoning ship?

 

[dcolak]

They say all op-amps sound the same, and all amps that are not frequency dependent sound the same.

Last couple of purchases made me re-think it.

Fosi was so bad with many speakers I tried it with, simply couldn't listen to it.

I would be disappointed if it's true that all op-amps sound the same.