Fosi Audio V3 Amplifier Review

[diego_cl]

I got my Fosi V3 version 2024 and I'm disappointed with the changes.

- The preamp output volume is too low.
- There's a new relay switch that engages when turning the volume up past the notch, but I don't like that it turns off when lowering the volume to minimum before reaching the notch.

The preamp output also lacks a crossover, so I'm using a passive crossover that loses some gain. Therefore, I'm not using the preamp output for my subwoofer.

I would need a dedicated on/off switch and a proper subwoofer output with a built-in crossover to like it more than the original Fosi V3.

 

[doug s.]

Local builder, Indonesia. Shipping cost, maybe bad idea for you.

But this dude shipped products to Germany too. You can find his YT channel, Wahyu Eko Romadhon aka W.E.R. all his social media are there, try his Facebook mostly active there.

I purchased his discrete opamps months ago. Green: anistardi's design, blue: elliot's design.

(Not showing off, bc all cheap products compare to sparkos, etc. or try to promote..just as collection and sharing for something i thought unique. hehe)

View attachment 351906

hi!

please tell me about these op amps. prices? sonic impressions? have you seen/heard the akliam lc2's?

thanks!

doug s.

 

[Guddu]

I would need a dedicated on/off switch

Fosi have surely learned something out of ZA3, the upcoming ‘Fosi v3 mono’ has ON/OFF toggle switch.

 

[diego_cl]

Fosi have surely learned something out of ZA3, the upcoming ‘Fosi v3 mono’ has ON/OFF toggle switch.

I understand that many people need to have the volume pot fixed, because they adjust volume at the DAC, or because they use multiple amps.

I actually like turning the amp on by turning the volume knob clockwise, but without the relay issue.

I hope the upcoming on/off switches are mechanical and not a push-button switch like the one used by the FX-Audio FX502SPRO... that amp turns on every time the electrical power is partially interrupted.

My first class-d amp was Breeze Audio TPA3116. It remains an excellent amplifier with a dedicated switch. Its only flaw was the linear potentiometer.

 

[Kunti]

Mission brand speakers MX1. Whether it's any good, there are very few reviews

 

[timiambeing]

I got my Fosi V3 version 2024 and I'm disappointed with the changes.

- The preamp output volume is too low.
- There's a new relay switch that engages when turning the volume up past the notch, but I don't like that it turns off when lowering the volume to minimum before reaching the notch.

The preamp output also lacks a crossover, so I'm using a passive crossover that loses some gain. Therefore, I'm not using the preamp output for my subwoofer.

I would need a dedicated on/off switch and a proper subwoofer output with a built-in crossover to like it more than the original Fosi V3.

Why do people want the sub out to have frequency controls? Surely the entire world and its mother uses active subwoofers, with comprehensive volume and frequency cut-off controls? And for those wanting high pass filters, you don’t reduce your frequency to the main pair, that’s crazy, you want the main pair full frequency and adjust the sub controls for a gentle crossover where the main pair fall off - basic stuff. For those looking for multiple amps to drive multiple passive speaker arrays there are plenty of boards on the market, plus there‘s MiniDSP for digital crossover control… for the price, and to be used in typical two channel stereo situations I think the Fosi gear is extraordinary, and to be honest nit picking about all these silly things like how the damn thing turns on drives me nuts. This is budget fun hifi - micro-budget by any standards - who cares how it damn well turns on, jeez! Just go buy something else…

…and now I’m out of here, was stupid idea to read ASR (of all forums!) first thing in the morning before coffee!

 

[somebodyelse]

And for those wanting high pass filters, you don’t reduce your frequency to the main pair, that’s crazy, you want the main pair full frequency and adjust the sub controls for a gentle crossover where the main pair fall off - basic stuff.

The crazy thing is sending frequencies much below tuning frequency to a reflex speaker, which these days is most of them. Even above tuning frequency the distortion tends to increase at the lower end of the frequency range, and xmax may limit output level, so letting the more capable sub handle things may improve performance. It's not by accident that studio style subs and AV systems have high pass filtering for the mains.

 

[Glades]

Just a heads-up. When running dual ZA3's in mono mode, I noticed they got really warm/hot. At first I thought it was a consequence of only running 1 channel per amp, however, decided to open them up and have a look at the thermal coupling.
There's a plate making contact with the case to distribute heat and the thermal paste wasn't applied evenly, leaving 60% of the plate(s) uncovered. Cleaned and re-applied (new) paste and both amps are now not warm (even after prolonged use).

Tip: when sliding in the board, apply a little pressure in the middle, so the plate bends slightly upwards and doesn't scrape the bottom o.t. case, scraping paste away.

 

[doug s.]

Why do people want the sub out to have frequency controls? Surely the entire world and its mother uses active subwoofers, with comprehensive volume and frequency cut-off controls? And for those wanting high pass filters, you don’t reduce your frequency to the main pair, that’s crazy, you want the main pair full frequency and adjust the sub controls for a gentle crossover where the main pair fall off - basic stuff. For those looking for multiple amps to drive multiple passive speaker arrays there are plenty of boards on the market, plus there‘s MiniDSP for digital crossover control… for the price, and to be used in typical two channel stereo situations I think the Fosi gear is extraordinary, and to be honest nit picking about all these silly things like how the damn thing turns on drives me nuts. This is budget fun hifi - micro-budget by any standards - who cares how it damn well turns on, jeez! Just go buy something else…

…and now I’m out of here, was stupid idea to read ASR (of all forums!) first thing in the morning before coffee!

when using subs, you definitely want to high pass the main speakers. if you use a quality outboard x-over, this will almost always result in your main speaker sounding better, unless the woofers in your main speakers are crossed over to the midrange <200hz. your main speakers and the amp(s) driving them will be so much happier. and, since the lower midrange starts ~200hz, the sound of the mains will be much cleaner.

re: these amps having sub outs, it's something i'd never use in a main system; casual listening system, ok. my main system always runs a preamp to an outboard x-over, sending signal to the main speakers and stereo subs.

doug s.

 

[RCL162]

hi!

please tell me about these op amps. prices? sonic impressions? have you seen/heard the akliam lc2's?

thanks!

doug s.

You can PM him on his social media, sir..i gave all his information there, on my post.

 

[doug s.]

You can PM him on his social media, sir..i gave all his information there, on my post.

thanks, i got the info; haven't queried him yet. i thought you might have the info at hand... (and also experience w/the akliam op amps i mentioned.)

doug s.

 

[Stereo20]

My speakers are Dynaudio dm 2/7 and 3/7.

HI,
before these two tpa3255s did you have another "classic" amplifier to compare?
thank you

 

[NZnoob]

I am looking at a basic stereo amp to assist a Marantz Cinema 70s (rated at 50w) to drive the Elac UBR62’s (6ohm/140w), which some websites say are “hard to drive”.

Please forgive the noob question, but if this Fosi V3 is 300w x2 (more than twice the 140w limit), does that mean it would fry my speakers? Or do these things actually put out a lot less juice than advertised?

If this thing would be a hazard for the speakers, does anyone have a better recommendation at a similar price point?

Thanks!

 

[Stereo20]

You're much more likely to fry your speakers with limited amplifier power than with a large power reserve

 

[NZnoob]

You're much more likely to fry your speakers with limited amplifier power than with a large power reserve

Does this mean it’s a good idea to put a Fosi between the AVR and speakers or not? Sorry, I’m about 3 days post thinking sound bars were peak audio, I know almost nothing about this topic (but trying to learn)!

 

[Stereo20]

I don't know your speakers, but an amplifier is unlikely to be too powerful.
Maybe wait for a comment from someone who knows them.

 

[DC4582]

I am looking at a basic stereo amp to assist a Marantz Cinema 70s (rated at 50w) to drive the Elac UBR62’s (6ohm/140w), which some websites say are “hard to drive”.

Please forgive the noob question, but if this Fosi V3 is 300w x2 (more than twice the 140w limit), does that mean it would fry my speakers? Or do these things actually put out a lot less juice than advertised?

If this thing would be a hazard for the speakers, does anyone have a better recommendation at a similar price point?

Thanks!

If you check the measured specs in the review you'll see the v3 needs the 48v power supply to even hit 141w max power per channel with both channels driven into 4 ohms. You would be fine using the v3 with the 48v power supply and those speakers. The 300w x2 is just marketing hype idk what they even base that on maybe the chip manufacturer specs.

 

[NZnoob]

If you check the measured specs in the review you'll see the v3 needs the 48v power supply to even hit 141w max power per channel with both channels driven into 4 ohms. You would be fine using the v3 with the 48v power supply and those speakers. The 300w x2 is just marketing hype idk what they even base that on maybe the chip manufacturer specs.

Thanks! That makes sense

 

[Guddu]

Does this mean it’s a good idea to put a Fosi between the AVR and speakers or not? Sorry, I’m about 3 days post thinking sound bars were peak audio, I know almost nothing about this topic (but trying to learn)!

Simple answer is - It’s totally safe for you to use Fosi v3 with DBR62

 

[DC4582]

Does this mean it’s a good idea to put a Fosi between the AVR and speakers or not? Sorry, I’m about 3 days post thinking sound bars were peak audio, I know almost nothing about this topic (but trying to learn)!

You need a line level input into the fosi - it takes standard left and right RCA cables. If i was getting something for a TV setup right now i would probably just get a wiim amp tbh.