Fosi Audio V3 Mono Amplifier Review

[Negatywny]

And also agree the FAQ is nonsense and contains marketing speak, what exactly is complex audio (as compared to what, simple audio?)?

simple audio - one tone, complex audio - multiple tones...?

 

[Cal_Cobra]

The V3M Kickstarter launch has an optional upgrade package that includes their new, unreleased and [apparently] still in development SP601 "DYNAUDIO EMIT20" killer speakers. As evident by their lack of updates, and variety of user based tuning demos, along their recent "Your Voice Matters: Help Shape the Sound of the SP601!" post which shows three different [crossover?] designs and their "SPL vs FREQ" test results, it would apper that speaker design is new territory for Fosi.

Prior to all this, they've posted several YouTube videos with various crossover settings, and compared against a pair of Dynaudio EMIT20's, with the audio differences for users to comment on. The Dynaudio EMIT20 SQ appears to be their goal for the SP601.

I love companies that are interactive with their customer base, and have good marketing folks that take customer feedback to product management/engineering to build what consumers want, but in this case, it appears that Fosi may be a bit lost when it comes to making audiophile grade speakers?

Now they've updated their Kickstarter V3M page that the optional SP601 speakers in the campaign will be delayed until August, which means we probably won't see the speakers land until Christmas [2024 ??].

As a pledge backer of the V3M+SP601 package, I personally do not mind the delay if it means they're building audiophile grade crossovers, or whatever they need to do in order to engineer the speakers to truly be Dynaudio EMIT20 killers, which seems to be their goal.

Still I wonder what is the cause of the SP601 speaker delay? @Fosi Audio ?

On a positive note, if this is your thing, Fosi Audio is very generously offering an additional opamp as compensation for the delay - "**Additionally, as a token of our apology, we would like to offer you an additional MUSES02 chip with your order.*"

Sort of a silver lining for those who ordered the speakers AND have the desire for the opamp upgrade. Fosi stated that just changing one per amp had a positive audible outcome. I wonder if the extra opamp with the speaker packages will sequester additional Kickstarter pledges? Perhaps they will reach their new $500K goal, it's getting close as the coundown on the final few days plays out.

Any speculation as to the SP601 delay?

 

[DavidM1]

Fosi stated that just changing one per amp had a positive audible outcome.

I couldn’t find the quote but my memory is that their wording was more along the lines of users might find a sound they like more. It would be a stretch to suggest they said changing chips would give an objective improvement.

 

[Cal_Cobra]

I couldn’t find the quote but my memory is that their wording was more along the lines of users might find a sound they like more. It would be a stretch to suggest they said changing chips would give an objective improvement.

Right, that makes sense and that's effectively what they claim here in their post from the KS V3M FAQ:

• The V3 Mono has three op-amps. What does each one do? And if I want to get a better sound, which one should I change?
  
  The V3 Mono's mainboard houses a total of three op-amps. One is located near the RCA input and is used to convert the RCA signal into a balanced signal. The other two are situated close to the amplifier chip. By replacing just one of the two, we can achieve the effect of sound signature tuning. Of course, if we were to replace both op-amps, the adjustment would be even more pronounced.
  Last updated: Mon, April 22 2024 7:50 AM PDT

 

[Sokel]

Right, that makes sense and that's effectively what they claim here in their post from the KS V3M FAQ:

• The V3 Mono has three op-amps. What does each one do? And if I want to get a better sound, which one should I change?
  
  The V3 Mono's mainboard houses a total of three op-amps. One is located near the RCA input and is used to convert the RCA signal into a balanced signal. The other two are situated close to the amplifier chip. By replacing just one of the two, we can achieve the effect of sound signature tuning. Of course, if we were to replace both op-amps, the adjustment would be even more pronounced.
  Last updated: Mon, April 22 2024 7:50 AM PDT

I don't know how to say it mildly but I'll say it anyway.
Such statements are either marketing or ignorance.

Fosi will maybe prove good at implementing stuff down the road,but given the fact that we had to explain to them what an electronic crossover is at another thread I wouldn't know for which of the two to blame them.

Please forget the op-amp stuff,people test them for years,no one proved any benefit and if things go south changing them you end up with a door-stopper.

 

[Great Sun Jester]

@AdamG Multiple Off topic posts deleted and 2 week thread bans issued as promised in post 1156 above.

 

[echt]

1. "All" and "None" are usually too radical expressions when applied to audio equipment, but as a general rule:

"issues can arise if multiple Class-D amplifiers switch simultaneously, but are not synchronized and managed.

Issues include:
• Power Supply Overloading resulting from all amplifiers switching on the same edge, causing the supply to droop or sag below the regulated voltage.
• Beat Interference or Beat Tones are audible tones that occur when slightly misaligned switching frequencies interact to create another frequency."

2. Yes and yes. In the case of the Fosi 3 Mono's TPA3255 chip, there is a TI note that better addresses this issue, see: Multi-Device Configuration for TPA32xx Amplifiers

3. It could be more than just coloration it could be "audible tones that occur when slightly misaligned switching frequencies interact to create another frequency".

In addition:

4. Power Supply Overloading is one reason why it might be a bad idea to run two Fosi 3 monoblocks from a single Fosi power supply. Admittedly, there may be better (and probably more expensive) power supplies that are less prone to this problem.

5. In comparison to the aforementioned Fosi monoblocks, the Fosi 3 PFFB STEREO represents a superior value proposition for the average home audio consumer, particularly in the context of power supply overloading and beat interference.

@PlasticDoc
Not sure whether to thank you or curse you for opening a can of worms I did not know existed. Guess I'll go with thanks!

@amirm
The only issues that concerns me on the V3 monos are the beat tone (significant concern) and power delivery contention (minor concern) mentioned by PlasticDoc above.

1. When you test monoblocks do you test only one channel or both driven simultaneously?

2. Would your tests pick up:
a) spurious beat tones
b) power supply overloading when both monoblocks accessing the wave edge simultaneously?

3. If the switching frequencies don't match exactly would we be expecting a frequency mismatch in a fraction of a hertz? single digits? What frequency band of spurious tone(s) do we expect to receive?

4. Overall, do you consider beat tones significant issue for switching frequency (Class D only?) amps.

Thanks.

 

[AdamG]

@AdamG Multiple Off topic posts deleted and 2 week thread bans issued as promised in post 1156 above.

Just FYI after 50-60 pages we lighten up on what is off topic. It’s your general thread drift. In product review threads we try to keep the early pages on topic so all the technical stuff is in the early sections. But when a thread like this ages we let more stuff go. It’s a balancing dance. We like to see active threads and conversations. This thread is at the point where we don’t police the conversation aggressively because that can have a negative effect on the dynamics of the conversation.

Appreciate the heads up though and I get your point. At some point we let the Members decide what they want to discuss.

 

[AdamG]

Just FYI after 50-60 pages we lighten up on what is off topic. It’s your general thread drift. In product review threads we try to keep the early pages on topic so all the technical stuff is in the early sections. But when a thread like this ages we let more stuff go. It’s a balancing dance. We like to see active threads and conversations. This thread is at the point where we don’t police the conversation aggressively because that can have a negative effect on the dynamics of the conversation.

Appreciate the heads up though and I get your point. At some point we let the Members decide what they want to discuss.

I do realize that was a lot of words when I could have said “Uncle” and this was my way of “Tapping out”. The Members win this round.

 

[MCH]

What i find amusing is that in the first days of TPA3255, boards, the main objective of the mod community was to bypass the opamps altogether and feed the chip directly with with a differential signal. People would claim all sorts of big improvements in sound quality

 

[FERCSA]

What i find amusing is that in the first days of TPA3255, boards, the main objective of the mod community was to bypass the opamps altogether and feed the chip directly with with a differential signal. People would claim all sorts of big improvements in sound quality

Hahh this is exactly what I'm doing. I don't say it is an improvement but my dac has only balanced outs. I was thinking to get the monos but why should I when I can simply add a balanced xlr pigtail to my v3?
CMRR get a small hit but the wire is very short and double shielded so doesnt matter.


In case someone needs it:
Pin1 +
Pin4 gnd
Pin7 -

 

[MCH]

Hahh this is exactly what I'm doing. I don't say it is an improvement but my dac has only balanced outs. I was thinking to get the monos but why should I when I can simply add a balanced xlr pigtail to my v3?
CMRR get a small hit but the wire is very short and double shielded so doesnt matter.

View attachment 371756
In case someone needs it:
Pin1 +
Pin4 gnd
Pin7 -

Yup, and I see the opamp socket comes super handy. That's a worthwhile easy mod

 

[Alex_Brouwer]

Try this? Or still go for the 2 5a?

 

[wybe]

Good questions, I am curios about this solution so I will take it. Worst case is have to buy an extra 10A brick.

 

[SMen]

Good questions, I am curios about this solution so I will take it. Worst case is have to buy an extra 10A brick.

And another filter (for worst case)

 

[SMen]

Try this? Or still go for the 2 5a? View attachment 371793

Still, it is a good gesture this. I wonder if @Fosi Audio measured the effect of the filter. The actual noise seemed quite low from memory from their post on this earlier in this thread.

 

[gasolin75]

 

[GGroch]

Any speculation as to the SP601 delay?

Untethered speculation is my superpower.

In a May 17 Kickstarter Update Fosi posted: "Help Shape the Sound of SP601" with the below graph attached.

Prototypes of the SP601 have been around for many months. I would think that if the speakers were shipping in June, the voicing would already have been decided. Certainly a delay to get this right makes sense.

Fosi's May 17 post reinforced my decision to postpone commitment. With no information on how the frequency graphs were measured, as well as the odd bass output, it would make it difficult for anyone to help them with voicing from a graph.

I believe Fosi has excellent in house amplifier engineers. Their attempt to crowdsouce frequency response with a graph makes me wonder if they have excellent speaker/acoustics engineers. I hope they will make an SP601 specific Kickstarter when the speakers are ready. Perhaps they could send prototypes to Amir or Erin for feedback before the final design is set.

 

[Negatywny]

"All backers who have chosen the 48V10A power supply + 2 sets of V3 Mono Combo will receive our custom-designed power filter for free!"

lol, want this slick power brick instead of two power bricks, to save space? Great, have this power brick and this free power filter xD

 

[rvsixer]

simple audio - one tone, complex audio - multiple tones...?

Their idea of complex audio was stated in the FAQ. I've been waiting for a Fosi explanation of just how the 10A power supply improves over the 5A for "...handling dynamically complex audio signals...", before the Kickstarter ends in a few hours.

At the price of three of these for LCR with the 10A supplies ($171/ch), you are not that far away from just getting a 4ch Buckeye Hypex based big boy amp (lol Erin love that term) all in one chassis with one power cord ($231/ch). And have a spare channel as backup.