Fosi Audio V3 Mono Amplifier Review

[Hador]

I have the two monos on top of each other (the DAC on top). Yesterday, after the monos had to work for several hours while watching TV at normal room volume, both of them suddenly produced an unpleasant noise in parallel, in addition to the normal sound. First quietly and then gradually increasing to a certain level.
I touched the amplifiers and both were very warm, despite the low volume. Turning it off and on didn't help. The noise came back immediately, a little quieter than before but rose back to the previous level.
The noise is independent of the volume set on the DAC.

I use the RCA inputs at 25 dB gain and RCA outputs on the DAC.

Can someone help me with this problem. Has anyone else had this too?

 

[ArturroD]

They are poorly constructed. They get too hot. Many have burned out, mine too. Return or exchange them.

 

[Hador]

I don't know much about amplifier electronics, but I previously thought that one advantage of the class D design was, among other things, its high efficiency.
Now I'm wondering why this heat production occurs even though only a minimum of the maximum possible performance is required.

 

[gentlejax]

They are poorly constructed. They get too hot. Many have burned out, mine too. Return or exchange them.

this is why I didnt grab them at first when they came out. guess my next amp will be a DIY kit.

 

[antcollinet]

I have the two monos on top of each other (the DAC on top). Yesterday, after the monos had to work for several hours while watching TV at normal room volume, both of them suddenly produced an unpleasant noise in parallel, in addition to the normal sound. First quietly and then gradually increasing to a certain level.
I touched the amplifiers and both were very warm, despite the low volume. Turning it off and on didn't help. The noise came back immediately, a little quieter than before but rose back to the previous level.
The noise is independent of the volume set on the DAC.

I use the RCA inputs at 25 dB gain and RCA outputs on the DAC.

Can someone help me with this problem. Has anyone else had this too?

If they both started producing the same noise at the same time, that suggests the problem is upstream - eg the DAC or further upstream - eg the TV losing sync with the DAC.

It is vanishingly unlikely they would both fail at exactly the same time with exactly the same fault.

Try a different source to feed the DAC or a different device into the amps.

 

[TikBLang]

this is why I didnt grab them at first when they came out. guess my next amp will be a DIY kit.

Better yet, DIY this bad boy amp (fosi-audio-v3-mono, no toggle switches, just the complete assembled board) and I will definitely get 'two' and put a very good ventilation and heatsink in one chassis!

 

[igfarm]

They run stone cold with 120mm fan running at 50%, which is inaudible. Fan only comes on when music is playing.

 

[Owis]

Fan only comes on when music is playing.

How have you got this configured? Is the fan running off a media player?

 

[igfarm]

How have you got this configured? Is the fan running off a media player?

Yes, basically running of the media player. In my case the LCD panel on the left of the picture runs some VU Meter software on a Raspberry Pi. The fan is connected to the PI's GPIO pins to spin them up when only when audio is playing.

 

[EJK]

They run stone cold with 120mm fan running at 50%, which is inaudible. Fan only comes on when music is playing.

View attachment 404560

Got a link to where you got the fan?

 

[igfarm]

I used some 120mm 4 pin Noctua fans I had form another project which are controlled via PWM input.

You can find similar fans on Amazon: https://a.co/d/hDAhsnQ

Fosi also does sell some fans for this purpose: https://fosiaudio.com/products/usb-powered-cooling-fan

 

[kingkoolkris]

I used some 120mm 4 pin Noctua fans I had form another project which are controlled via PWM input.

You can find similar fans on Amazon: https://a.co/d/hDAhsnQ

Fosi also does sell some fans for this purpose: https://fosiaudio.com/products/usb-powered-cooling-fan

That's some ghetto-modding

 

[Hipster Doofus]

Only 14 of these for my home theatre

 

[DavidM1]

View attachment 405193Only 14 of these for my home theatre

This feels like the internet has confused my forums. Home theatre or a wet-dry rig?

 

[Bassmister]

I have Emotiva XT3 Towers and XC1 center.

I have a Onkyo RZ70 receiver

I have dual Klipsch RP 1400SW subwoofers.

A review on YouTube said that these speakers need more watts than traditional speakers because they are 4 ohms.

So I looked for amplifiers and found the Fosi V3 Mono. After reading the review it delivers 200w of actual power to the speakers. So with 3 amplifiers I could power my front speakers. Then I became curious about Bi Amping. Most people say it doesn't do anything and some say it helps deliver more clarity. Because Fosi V3 are inexpensive I bought a single Fosi v3 with a 5A power supply and I bought dual Fosi v3 with a 10A power supply to power to blocks.

I plugged the amps in and so far I'm impressed with the sound.

I have a RCA Y splitter from the preouts and then connect to each bi amp port on the speaker.


Two amps are connected to one power supply and each amp is connected to a high frequency terminal and low frequency terminal. The amps then provide 200w to each terminal.

I read that bi amping won't make a noticeable difference. So I'm asking would a single 500w amp sound better then dual 240w amps

 

[antcollinet]

So I'm asking would a single 500w amp sound better then dual 240w amps

Well first - with your dual 240W amps, you are not delivering 480W to the speakers. This is because the power spectral density of music falls off rapidly with frequency.

This means the power into high frequencies is much lower than into low frequencies at the same volume, depending on where the crossover split is between the low and high frequency terminals is. If high frequency dirves only the tweeters, it is likely only needing 10 to 30W with 240W going into the lower frequencies.

If you use a single 500W amp, this means you have much more power available for the low frequencies where it is needed. But this will only deliver better sound quality if you currently need more than the 240W the low frequencies are getting, and the 240W amp is clipping. I very much doubt this is the case, because if it were your sound pressure levels would be in the dangerous-for-your-ears territory, and it also wouldn't be "impressive" sounding.

 

[Bassmister]

Well first - with your dual 240W amps, you are not delivering 480W to the speakers. This is because the power spectral density of music falls off rapidly with frequency.

This means the power into high frequencies is much lower than into low frequencies at the same volume, depending on where the crossover split is between the low and high frequency terminals is. If high frequency dirves only the tweeters, it is likely only needing 10 to 30W with 240W going into the lower frequencies.

If you use a single 500W amp, this means you have much more power available for the low frequencies where it is needed. But this will only deliver better sound quality if you currently need more than the 240W the low frequencies are getting, and the 240W amp is clipping. I very much doubt this is the case, because if it were your sound pressure levels would be in the dangerous-for-your-ears territory, and it also wouldn't be "impressive" sounding.

Very Interesting. I still have some confusion. The RZ70 has a preouts for the front speakers. With a Y splitter RCA cable I can take the signal and make it into two. Each signal going into a Fosi Mono v3. Then each Fosi going into the high frequency and low frequency.

Because it is not active bi amping the speakers have a internal crossover. But each Fosi v3 mono is sending a full signal into each port in the back of the speaker. The speaker then uses the internal crossover to send the correct signal to the speaker.

I think what you are saying is because of the internal crossover even tho a full range signal is going into the high frequency terminal the internal crossover only uses 10-30w so it does not take advantage of the remaining 240w. Where as the low frequency uses all the 240w.

If you had a 500w amp like a NCore Buckeye then the low frequency would have more then 240w to use to make the bass sound better with only 10w to 30w going to the tweeter?

Is this correct?

Because two Fosi v3 mono blocks are connected to one 48v 10A power supply does this cause any sort of issue? I assumed both monoblocks provide the same 200w full range single to each low and high port and it isn't likely the entire power supply is being used so there would be any problem? Sound wise hi res music sounds great. However on some streams I can hear small little single pops and I don't know if it because of the audio track.

I don't want to damage my speakers. I'm considering getting individual power supplies 48v 5A for each monoblock so two monoblocks won't interact with each other. And because I have five monoblocks I might as well passive bi amp right?

 

[Bassmister]

Very Interesting. I still have some confusion. The RZ70 has a preouts for the front speakers. With a Y splitter RCA cable I can take the signal and make it into two. Each signal going into a Fosi Mono v3. Then each Fosi going into the high frequency and low frequency.

Because it is not active bi amping the speakers have a internal crossover. But each Fosi v3 mono is sending a full signal into each port in the back of the speaker. The speaker then uses the internal crossover to send the correct signal to the speaker.

I think what you are saying is because of the internal crossover even tho a full range signal is going into the high frequency terminal the internal crossover only uses 10-30w so it does not take advantage of the remaining 240w. Where as the low frequency uses all the 240w.

If you had a 500w amp like a NCore Buckeye then the low frequency would have more then 240w to use to make the bass sound better with only 10w to 30w going to the tweeter?

Is this correct?

Because two Fosi v3 mono blocks are connected to one 48v 10A power supply does this cause any sort of issue? I assumed both monoblocks provide the same 200w full range single to each low and high port and it isn't likely the entire power supply is being used so there would be any problem? Sound wise hi res music sounds great. However on some streams I can hear small little single pops and I don't know if it because of the audio track.

I don't want to damage my speakers. I'm considering getting individual power supplies 48v 5A for each monoblock so two monoblocks won't interact with each other. And because I have five monoblocks I might as well passive bi amp right?

 

[antcollinet]

Is this correct?

Pretty much. Though it is not the crossover that causes lower power into the high range. The crossover just separates the frequencies. The lower power for the high frequencies is already built into the full range signal.

Because two Fosi v3 mono blocks are connected to one 48v 10A power supply does this cause any sort of issue?

No

However on some streams I can hear small little single pops

Most likely due to dropouts in the data stream somewhere, most likely in your house rather than outside it. It could be built into the source file, but if streaming from a service this would be a pretty bad failing.

And because I have five monoblocks I might as well passive bi amp right?

You can if you like, but it won't make any improvement to the sound - just complicates the wiring.

 

[kingkoolkris]

I got a replacement board for one of my dead V3 monos from Fosi. Working fine now again obviously. Nothing wrong I can see with the dead board though, nothing blown etc.