Fosi Audio V3 Amplifier Review

[TonyJZX]

depends on your speakers

if you own the famous klipsh heresys then 34w is fine

but all this being equal i would take the 48v psu given the avg. speaker is probably not 99db SPL

 

[Juampa1989]

depends on your speakers

if you own the famous klipsh heresys then 34w is fine

but all this being equal i would take the 48v psu given the avg. speaker is probably not 99db SPL

The klipsch heresies with half a volume knob at 32v are already moving strongly. You have half a knob left. I ideally recommend using dacs with 2 vrms output as a minimum and maximum. This way you get all the juice out of it without distortion. I have a 3 vrms one and at half knob it starts with distortion, so I changed it.

 

[antcollinet]

My mean is, which psu will make sound quality better. Thank u.

Sound will be the same if you stay within the volume limit, and don't drive the amp to clipping.

48V will allow you to do that at higher power.

 

[Yorkshire Mouth]

This thread gets a mention in Audio Masterclass.

 

[peng]

Just got the V3, 32 V PS setup and ran a few sweeps, here are the results:
The FR graphs shown were based on variable smoothing.

Objectively I don't think there is even 1 dB difference here and there between the two, subjectively the V3 sounds as good as any other amps I currently have and had before, by memory. The NAD sounds great too, I really can't tell which one sounds better and in blind test I don't believe any humans can score better than 60% consistently but it obviously could not be proved. Anyway the objective is just to see if I would experienced what S.T. experienced, and I didn't. He pushed the amps much harder, I tried too but the V3 maxed out at about 92 dB average based on pink noise. I am sure I can push it to over 100 dB but I would have to drive it with the NAD's pre outs, there is no point doing it as I am not a reviewer of torture tester. As it was I had to plug my ears during the sweeps already. Edit: I should do another sweep tomorrow with Dirac Live completely shut off/exited, and I am sure I could get a lot more SPL that way.

FOSI AUDIO V3 THD BASED ON REW SWEEP

NAD C326BEE THD, BASED ON REW SWEEP

 

[Juampa1989]

I got 103 db spl with the 32v 5a, 88db sensitivity speakers. I compared it with the topaz sr10 v2 and the fosi tb10d, and the v3 sounds clearer, the voices are clearer. Dac 1.5 vrms.

 

[peng]

I got 103 db spl with the 32v 5a, 88db sensitivity speakers. I compared it with the topaz sr10 v2 and the fosi tb10d, and the v3 sounds clearer, the voices are clearer. Dac 1.5 vrms.

My LS50's sensitivity is 85 dB and I forget to exit DL, that probably would make a big difference, like 10 dB or more

 

[crx]

Sorry didn't have time to read the whole thread.

I was one of the kickstarter backers of this thing and just now trying it out (48v version).

I have it running my Auratones 5C, specs say they have Power handling: 25W RMS/50W Peak.

It does ok. I like it. I'm not sure it really has 300Wx2 though, lol. I think it surely has at least 25Wx2 to drive Auratones, but my volume dial is pretty much at max and they're not too loud...

I was hoping to get another little Fosi amp for my NS10Studios, but those have power needs: Capacity: 60 watts(PROGRAM), 120 watts(MAX) Nominal Impedance: 8 ohms

Will it be comfortably sufficient for the NS10s (somehow I doubt it)? They say if the amp too weak tweeters will eventually fail, if too strong it will just easily blow them up at slight accident.

Sorry, I find all this technical stuff a bit too confusing. If V3 is too weak what other model would work? I don't want a big box on the desk, trying to stay minimalistic.

 

[TonyJZX]

my reading is that the V3 is a amp with a lot of power able to push just about every common speaker to spl that isnt healthy or sustainable in modern polite society

89w at 8 ohm, 140w at 4 ohms.., yeah this thing is a power house

i think people are unduly caught up with V3 power because of a few people here there and everywhere who dont know what they are doing... and these people are doing reviews, further spreading their lack of knowledge

if you have a speaker than falls outside of what is a 'normal' speaker, eg. electrostats, then you should know what your bought

Fosi gave a reason why they advertise "300w" and if it does 140w x 2 at 4 ohms then really this isnt false advertisement?

Amir is known to test hard and its not out of the ordinary to expect that in some tests, it could do 150w x 2 @ 4 ohms?

 

[nawfal07]

Nice. I'm thinking of adding another pair of overhead speakers to my home theater setup, this can do the job of powering them.

Thanks for the review @amirm !

 

[saberger0357]

Sorry didn't have time to read the whole thread.

I was one of the kickstarter backers of this thing and just now trying it out (48v version).

I have it running my Auratones 5C, specs say they have Power handling: 25W RMS/50W Peak.

It does ok. I like it. I'm not sure it really has 300Wx2 though, lol. I think it surely has at least 25Wx2 to drive Auratones, but my volume dial is pretty much at max and they're not too loud...

I was hoping to get another little Fosi amp for my NS10Studios, but those have power needs: Capacity: 60 watts(PROGRAM), 120 watts(MAX) Nominal Impedance: 8 ohms

Will it be comfortably sufficient for the NS10s (somehow I doubt it)? They say if the amp too weak tweeters will eventually fail, if too strong it will just easily blow them up at slight accident.

Sorry, I find all this technical stuff a bit too confusing. If V3 is too weak what other model would work? I don't want a big box on the desk, trying to stay minimalistic.

If you go back and read the review that started this thread, you'll see that(as indicated in the post above) at 8 ohms the V3 is capable of 89 watts with the 48v brick(141 watts @ 4 ohms). You should have no difficulty driving most speakers, including the Yamaha's, which are fairly efficient at 90 dB @ 1W. The power handling capability numbers are irrelevant for the most part.

Also with the tapered volume control, a lot of the gain is past 3 pm. So if you have a preamp controlling overall gain, turn the V3 all the way to the right and control via the pre.

 

[peng]

my reading is that the V3 is a amp with a lot of power able to push just about every common speaker to spl that isnt healthy or sustainable in modern polite society

89w at 8 ohm, 140w at 4 ohms.., yeah this thing is a power house

i think people are unduly caught up with V3 power because of a few people here there and everywhere who dont know what they are doing... and these people are doing reviews, further spreading their lack of knowledge

if you have a speaker than falls outside of what is a 'normal' speaker, eg. electrostats, then you should know what your bought

Fosi gave a reason why they advertise "300w" and if it does 140w x 2 at 4 ohms then really this isnt false advertisement?

Amir is known to test hard and its not out of the ordinary to expect that in some tests, it could do 150w x 2 @ 4 ohms?

I agree with you for the most part, but I am not clear about the basis for them to advertise 300 W X2, their own website specs show the following:

From my understanding from the TI website,

Total Output Power at 10% THD+N – 315-W Stereo into 4 Ω in BTL Configuration – 180-W Stereo into 8 Ω in BTL Configuration – 600-W Mono into 2 Ω in PBTL Configuration

and BTL configuration would require two such chips. Unless I missed something, the V3 has only one TBA3255 chip, so how is it possible to do 300WX2@4 ohm, even at 10% THD? Let alone the way they show the specs, it could easily mislead someone to think it could do 300Wx2@4 ohm, 0.003% THD. Yes, someone with audio electronics common sense should know better, so I guess that kind of advertising practices is acceptable in terms of the "norm", I really don't know though..

Regardless, with the 20% discount offer, I ordered a second one for another pair of my KEF speakers. Since the sale is for ordering from Fosi directly, I ordered one with the 48 V PS, for USD 88, they have to ship it all the way from Hong Kong.

Specifications​

Specifications	Details
Model	V3
Chip Set	TI TPA3255
Output Power	300Wx2 @4Ω
Terminating Impedance	2-8Ω
Input Mode	RCA
Output Mode	Speaker Output + Pre-out
Frequency Range	20Hz-20kHz(±0.1dB)
SINAD	88dB
THD	0.003%
SNR	≥110dB
Control Knob	Built-in Logarithmic Taper A pot
Device Dimension	6.5x4.1x1.4 inches
DC Input Range	24-48V
Power Supply	32V/5A, 48V/5A

 

[saberger0357]

300 watts is the unrealistic measurements by the chip maker at 4 ohms with a 48v/10a power supply at higher distortion levels.

 

[peng]

300 watts is the unrealistic measurements by the chip maker at 4 ohms with a 48v/10a power supply at higher distortion levels.

At that level (300 WPC), it is not just the power supply any more. My point is, the chip amp used is only rated 315 WPC based on the BTL configuration, according to the manufacturer, i.e. TI. TI's datasheet makes it clear that 300 W is achievable at 10% THD in BTL so we can't say they are being unrealistic, unless someone measure the amp(s) in BTL configuration.

https://www.ti.com/lit/ds/symlink/tpa3255.pdf?ts=1695196355998&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPA3255

From the Fosi Audio website, I found no evidence that they are using two chips, and/or configure the V2 in BTL, but I could have missed something..

 

[GGroch]

300 watts is the unrealistic measurements by the chip maker at 4 ohms with a 48v/10a power supply at higher distortion levels.

Texas Instruments encourages their manufacturer's to advertise maximum specs as needed. See the linked Texas Instrument White Paper advising manufacturers how to advertise their chip power ratings that I posted here.

Key Quote from the 4th page:
The need for attractive marketing strategies requires TI customers to devise creative ways to use power rating for advertisements.
This paper assists TI customers in determining the suitable power rating to be used in the advertisement of their products. TI supports customers internationally and understands that each region of the world requires different marketing strategies. While the power rating for the US market is dictated by the FTC, other countries may not be restricted to such requirements. In those cases, TI customers are open to choose the acceptable power rating for advertisement. As mentioned in the introduction, PMPO generally is not well-defined and accepted as an audio performance measurement. It is used mostly for advertisements.

Note this was written before 2005, since then the FTC no longer enforces power rating restrictions in the U.S.

I do not think it is smart for Fosi to advertise these max chip power ratings on the V3, even if TI says it is OK. The V3 is Fosi's first product aimed at tech savvy audiophiles who read and understand specs. if they are smart future advertising of the V3 and other products aimed at this market will use their actual measured specs for the product, not the TI chip spec ratings.

 

[Joe Smith]

I agree, it is a bit of "having your cake and eating it too." I think Fosi made the V3 in part due to our comments here and other top audio boards about amps such as the Aiyima A07, and wanted the more savvy user to buy it. But when all of the competing amps are pushing the high power ratings, if they don't do so, then the less savvy might not even consider the V3. Given the state of competition right now for these companies, and the tight profit margins, it's kind of a tough spot.

 

[saberger0357]

Texas Instruments encourages their manufacturer's to advertise maximum specs as needed. See the linked Texas Instrument White Paper advising manufacturers how to advertise their chip power ratings that I posted here.

Key Quote from the 4th page:
The need for attractive marketing strategies requires TI customers to devise creative ways to use power rating for advertisements.
This paper assists TI customers in determining the suitable power rating to be used in the advertisement of their products. TI supports customers internationally and understands that each region of the world requires different marketing strategies. While the power rating for the US market is dictated by the FTC, other countries may not be restricted to such requirements. In those cases, TI customers are open to choose the acceptable power rating for advertisement. As mentioned in the introduction, PMPO generally is not well-defined and accepted as an audio performance measurement. It is used mostly for advertisements.

Note this was written before 2005, since then the FTC no longer enforces power rating restrictions in the U.S.

I do not think it is smart for Fosi to advertise these max chip power ratings on the V3, even if TI says it is OK. The V3 is Fosi's first product aimed at tech savvy audiophiles who read and understand specs. if they are smart future advertising of the V3 and other products aimed at this market will use their actual measured specs for the product, not the TI chip spec ratings.

I agree that, at least for those of us who scrutinize ASR and other similar audio forums, being as transparent as possible would be a benefit for Fosi. But realistically, they are not the first, only company to "devise creative ways to use power ratings for advertisements"(I love that). Audio companies have been doing this forever. It's always been up to the consumer to try to sort through the hype and if the product their contemplating buying will suit their needs. Having resources like ASR is great, and I'm guessing that a fair amount of folks who buy Fosi products at least know about this site, or take the numbers with a grain of salt, or both.

 

[crx]

Thank you. Any other Fosi amp that can do clean 120W per channel at 8 Ohms?

 

[TurtlePaul]

I agree with others that it is hard to not advertise “2x300” when all the competitors are doing it.

Regarding 120 W per channel i to 8 ohm, I think you would need to get something like a 52 volt 5 amps PSU. I bet the V3 could do 120 WPC 8 ohm with such a supply. 48 volt won’t cut it. Very few chip amps come with 50V+ PSUs because TI specs the max voltage as 55V and amp makers want to be well below that.

I think, in general, many people underestimate what 100 watts actually delivers for real speakers in real setups. There are ear ringing frat parties with far far less power.

 

[burkm]

The stated wattages per impedance are completely wong, but it seems, that Fosi ist just following the recommendations of TI, because everybody else seems to publish those unrealistic values, which could not be achieved with the given (standard-)power supplies.
Those values measured by amir are the real wattages (standardized) achivable by using one of the normally delivered (standard) power supplies.
But still those realistic wattages are "good" by any means for the amount (price) charged and the quality achieved...