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Fosi v3 Mono - User Impressions | Owner's Thread

Guddu

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Dear FMs, [<< If you haven't seen Amir's review yet (which is super unlikely): Amir's Measurements & Review of Fosi v3 Mono >>]

A pair of Fosi v3 mono arrived on my desk last evening, I feel that this amplifier deserves its own User Impressions & Owner's Thread.
I am hoping that it will keep other measurement & review thread limited to its purpose and rest could get a place here in this thread.

I mean to summarize:
> what I get as a buyer or user of Fosi v3 mono amplifier pair
> aspects other than measurements that you might be interested in
> testing features & functions to see if there are any issues and how could get around those, if any
> I also hope that this thread could provide some information as to "what to expect" while you are buying this amplifier

*** I hope other Fosi v3 mono owners can also sum up their feedback and some work arounds here to help other potential future Fosi v3 mono owners ***

Packaging & transportation:
It came in decently packed, box had signs of transportation torture but nothing to be worried about.
I think it would be better with Amazon delivery.

1714164521485.png


Look & Feel:
> I don't need to say much on this, but this amplifier looks even better. While Fosi ZA3 had slightly non-shiny matt look, Fosi v3 mono's case is shiny-er looking better than ZA3 case to me.
> It's height marches with Topping E50 DAC and/or Topping PA7 amplifier.
> Shouldn't need to be saying again, but it looks cute under my TV. Low profile makes things really easy for placement however speaker cable termination requires some consideration, notes added.
> No matter how hard I try to ignore but the speaker binding post is small, its same as used in other Fosi amplifier and so some considerations are needed.

Back Panel.png


Power Supply:
> I got 48v 10a PSU, and it is supplied with a splitter cable to connect to 2 amplifiers.
> PSU is heavy, which feels good and safer. 18 AWG cables are used by manufacturer which is good enough for 10a current (in general), details in picture below:

PSU & Splitter Cable.JPG


> In comparison to other 48v PSUs supplied with other amplifiers:
48v PSU Comparision E.jpg


IMG_E1830.JPG


My Setup, Connectivity and Pairing devices:

PC & nVidia Shield Pro (source) >>>> Topping E50 >>>>balanced out>>>> Fosi v3 Mono Amplifiers >>>> ELAC DBR62 Speakers

IMG_E1820.JPG

Note: Center Speaker in pic isn't connected to this setup

IMG_E1818.JPG


Pic v3 mono - far 1 E.jpg



Auto ON/OFF
> I found it working every time, without any issues or any miss
> it's rather more convenient than triggered in IMO, it turns off after about 10-11 minutes when no signal and turns up immediately by any signal

Idle Power - Powered ON vs Auto
> Measured on 20a smart plug
> When Powered ON but No music playing: approx. 20W (v3 mono, pair)
> When toggle set to Auto but its OFF: approx. 10W (v3 mono, pair)
> When toggle set to OFF, no power drawn captured
1714168241313.png


Amplifier Case Temperature
> As noted in above statement, amplifier uses at least 10W on idle with Auto setting but Off and 20W on idle when powered ON
> Sitting approx. 2.5 meters from speakers, listening to 70-75 db which is my normal listening volume, it never went over 22W
> With 20-22W power consumption, amplifier chassis did go a bit hot for sure
> I pushed it around 30W and I didn't like touching the case, however I would worry too much
> I did not feel that I should measure the temperate, given my normal listening requirements, but I will probably try over the weekend just to note it down here if possible


Illusional and Delusional Stuff - How I feel about Fosi v3 Mono after listening for few hours

Note:
>>
Amir has provided all the measurements that could tell you more than anything and anyone to evaluate the amplifier objectively.
>> And So, you might want to ignore this part as its purely based on my setup, in-room response and my likings.

I use MusicBee and use equalizer on the player to manage some in-room response anomalies, which I forgot after connecting and moving from Topping PA7 to v3 mono.
but anyways, It sounded superb just like PA7 does in my setup. There was not any blind AB test, which will be done probably over the weekend with some friends, but I totally doubt that anyone could tell a difference even if there is any.
So, no comparisons.
These amplifiers with Elac DBR62 are sounding amazing, no complaints.
I am trying hard not to use any words that someone would come after me reading, but its simply FANTASTIC.

With my confidence and doubts, I fired up REW to quickly see how different is frequency response in my room at my listening position and I wasn't surprised seeing it was more or les same as PA7 with minor variance here & there that I can perhaps not hear.

If you want to look at the below REW measurements, please ignore un-evenness and only look at the differences. I try to make up for a few of these issues with EQ on music player, which isn't subject to REW measurements.

1714170535913.png

If anything, it only appears a bit better. My Topping PA7 isn't liking me saying this.

====================================
Some considerations, could be helpful for planning:
====================================

Speaker cable connectivity:
> Banana Plug is the safest option for these amplifiers considering spacing between binding posts and PSU connector.

Vanya - Covid Card.jpg


Amplifier placement if using splitter cable
> Splitter cable can allow about 2 feet or 25-26 inches stretch or distance

Popping Noise/Sound
> There is popping noise/sound on turn on/off, if you want to listen for any reason: Fosi v3 Mono Power ON-OFF Pop.m4a
> Note*: The sound clip was recorded on iPhone kept about 1 feet from speaker.
> Amir has notified in his measurements as well:
index.php


Humming Sound issue when only one amplifier is powered ON - Probably Resolved Now!
> As we heard humming sound issue when simple PSU is used for v3 mono pair but only one amplifier is ON, I did not find it in the units I received.
> I don't know if it is resolved or I could not replicate it, but I have tested these many times with one amplifier ON/OFF/Auto however never found the issue

=========================================

While I plan to add on more details later as I observe, capture or measure something that could be useful for someone, I am wrapping it up here with a note that if you need mono bocks for a small room then you will surely miss something if you don't get these Fosi v3 mono amplifiers in your list (amazon makes it easier to try).
I wasn't aware that these are getting delivered, so thanks @Fosi Audio.
 
Last edited:

Yannick

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Thanks for the first impressions! Great idea to get some non-rigorous-measurement but still useful information out there.

Just wondering: does the popping noise of turning on/off also take place when using the Auto On/Off? Or is limited to when flicking the switch physically from On to Off or vice versa?
 

MCH

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Thanks @Guddu
I am interested in the power off "pop". I have listened to the clip but the noise of the relays doesn't make it easy to hear the pop noise from the speakers, or when it is on or off.
What I am interested in is the Pop noise from the speakers when the amp is turned OFF.

Actually Amir measurement shows a perfect no noise turn off. I don't know how Amir tested but looking at the timeline I can imagine he just toggles the on/off switch on and then off.

Can you confirm you can hear a "pop" noise from the speakers when you turn off the amp via the on/off switch?
Thanks man!
 
OP
Guddu

Guddu

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Thanks @Guddu
I am interested in the power off "pop". I have listened to the clip but the noise of the relays doesn't make it easy to hear the pop noise from the speakers, or when it is on or off.
You are right, my phone was 1 feet away from speaker and approximately 4-5 away from amplifier but still relay sound is captured.
Actually relay probably makes as much sound as speaker pop, and relay is quite catchy sound.
I will try to capture it again, but it’s loud enough to be easily listened from 3-4 meters.


Can you confirm you can hear a "pop" noise from the speakers when you turn off the amp via the on/off switch?
Yes, it’s hit and miss on turning off, but it’s there most of the time.

Although it can be annoying, but it’s not too loud. I have heard quite loud pop from a few others.
 

SMen

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Good idea @Guddu to set up this thread - lucky you to get these early! Seeing your comparison photos, I'm quite glad I went for the 10A supply to power both.
 
OP
Guddu

Guddu

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Just wondering: does the popping noise of turning on/off also take place when using the Auto On/Off? Or is limited to when flicking the switch physically from On to Off or vice versa?
Pop is surely there when using on/off on toggle switch or on/off on power plug/strip.
I just gave it 8-10 attempts to check on Auto, and it mostly gives it when it turns ON after getting a signal.
I didn’t find any pop after 2-3 auto off, required to wait 10-11 min every time, but didn’t get any pop when it goes auto off.

The only question to my mind is if it could be harmful for speakers, to me it feels mild and may be safer but I can no way to find out without risk of busting my speakers :(
 

Megumin

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Dear FMs, [<< If you haven't seen Amir's review yet (which is super unlikely): Amir's Measurements & Review of Fosi v3 Mono >>]

A pair of Fosi v3 mono arrived on my desk last evening, I feel that this amplifier deserves its own User Impressions & Owner's Thread.
I am hoping that it will keep other measurement & review thread limited to its purpose and rest could get a place here in this thread.

I mean to summarize:
> what I get as a buyer or user of Fosi v3 mono amplifier pair
> aspects other than measurements that you might be interested in
> testing features & functions to see if there are any issues and how could get around those, if any
> I also hope that this thread could provide some information as to "what to expect" while you are buying this amplifier

*** I hope other Fosi v3 mono owners can also sum up their feedback and some work arounds here to help other potential future Fosi v3 mono owners ***

Packaging & transportation:
It came in decently packed, box had signs of transportation torture but nothing to be worried about.
I think it would be better with Amazon delivery.

View attachment 366024

Look & Feel:
> I don't need to say much on this, but this amplifier looks even better. While Fosi ZA3 had slightly non-shiny matt look, Fosi v3 mono's case is shiny-er looking better than ZA3 case to me.
> It's height marches with Topping E50 DAC and/or Topping PA7 amplifier.
> Shouldn't need to be saying again, but it looks cute under my TV. Low profile makes things really easy for placement however speaker cable termination requires some consideration, notes added.
> No matter how hard I try to ignore but the speaker binding post is small, its same as used in other Fosi amplifier and so some considerations are needed.

View attachment 366027

Power Supply:
> I got 48v 10a PSU, and it is supplied with a splitter cable to connect to 2 amplifiers.
> PSU is heavy, which feels good and safer. 18 AWG cables are used by manufacturer which is good enough for 10a current (in general), details in picture below:

View attachment 366029

> In comparison to other 48v PSUs supplied with other amplifiers:
View attachment 366031

View attachment 366032

My Setup, Connectivity and Pairing devices:

PC & nVidia Shield Pro (source) >>>> Topping E50 >>>>balanced out>>>> Fosi v3 Mono Amplifiers >>>> ELAC DBR62 Speakers

View attachment 366033
Note: Center Speaker in pic isn't connected to this setup

View attachment 366034

View attachment 366035


Auto ON/OFF
> I found it working every time, without any issues or any miss
> it's rather more convenient than triggered in IMO, it turns off after about 10-11 minutes when no signal and turns up immediately by any signal

Idle Power - Powered ON vs Auto
> Measured on 20a smart plug
> When Powered ON but No music playing: approx. 20W (v3 mono, pair)
> When toggle set to Auto but its OFF: approx. 10W (v3 mono, pair)
> When toggle set to OFF, no power drawn captured
View attachment 366038

Amplifier Case Temperature
> As noted in above statement, amplifier uses at least 10W on idle with Auto setting but Off and 20W on idle when powered ON
> Sitting approx. 2.5 meters from speakers, listening to 70-75 db which is my normal listening volume, it never went over 22W
> With 20-22W power consumption, amplifier chassis did go a bit hot for sure
> I pushed it around 30W and I didn't like touching the case, however I would worry too much
> I did not feel that I should measure the temperate, given my normal listening requirements, but I will probably try over the weekend just to note it down here if possible


Illusional and Delusional Stuff - How I feel about Fosi v3 Mono after listening for few hours

Note:
>>
Amir has provided all the measurements that could tell you more than anything and anyone to evaluate the amplifier objectively.
>> And So, you might want to ignore this part as its purely based on my setup, in-room response and my likings.

I use MusicBee and use equalizer on the player to manage some in-room response anomalies, which I forgot after connecting and moving from Topping PA7 to v3 mono.
but anyways, It sounded superb just like PA7 does in my setup. There was not any blind AB test, which will be done probably over the weekend with some friends, but I totally doubt that anyone could tell a difference even if there is any.
So, no comparisons.
These amplifiers with Elac DBR62 are sounding amazing, no complaints.
I am trying hard not to use any words that someone would come after me reading, but its simply FANTASTIC.

With my confidence and doubts, I fired up REW to quickly see how different is frequency response in my room at my listening position and I wasn't surprised seeing it was more or les same as PA7 with minor variance here & there that I can perhaps not hear.

If you want to look at the below REW measurements, please ignore un-evenness and only look at the differences. I try to make up for a few of these issues with EQ on music player, which isn't subject to REW measurements.

View attachment 366043
If anything, it only appears a bit better. My Topping PA7 isn't liking me saying this.

====================================
Some considerations, could be helpful for planning:
====================================

Speaker cable connectivity:
> Banana Plug is the safest option for these amplifiers considering spacing between binding posts and PSU connector.

View attachment 366036

Amplifier placement if using splitter cable
> Splitter cable can allow about 2 feet or 25-26 inches stretch or distance

Popping Noise/Sound
> There is popping noise/sound on turn on/off, if you want to listen for any reason: Fosi v3 Mono Power ON-OFF Pop.m4a
> Note*: The sound clip was recorded on iPhone kept about 1 feet from speaker.
> Amir has notified in his measurements as well:
index.php


Humming Sound issue when only one amplifier is powered ON - Probably Resolved Now!
> As we heard humming sound issue when simple PSU is used for v3 mono pair but only one amplifier is ON, I did not find it in the units I received.
> I don't know if it is resolved or I could not replicate it, but I have tested these many times with one amplifier ON/OFF/Auto however never found the issue

=========================================

While I plan to add on more details later as I observe, capture or measure something that could be useful for someone, I am wrapping it up here with a note that if you need mono bocks for a small room then you will surely miss something if you don't get these Fosi v3 mono amplifiers in your list (amazon makes it easier to try).
I wasn't aware that these are getting delivered, so thanks @Fosi Audio.
Wasn't standby power supposed to be 0.5W? I assume the "toggle set to Auto but its OFF" would be standby right?
 
OP
Guddu

Guddu

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Wasn't standby power supposed to be 0.5W?
I can only tell what I am able to confirm myself, and I am seeing it to be between 8.5w to 10w as you can see in screenshot as well from original post.
Please note that it’s for a pair, so each amplifier is consuming around 5w or so.

I assume the "toggle set to Auto but its OFF" would be standby right?
I would say - Yes.
 

Megumin

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I can only tell what I am able to confirm myself, and I am seeing it to be between 8.5 w to 10w as you can see in screenshot as well from original post.
Please note that it’s for a pair, so each amplifier is consuming around 5w or so.


I would say - Yes.
Strange, in the other thread Fosi themselves mention the supposed 0.5W standby power usage. Even halved that is a factor of 10.

This was after the 10 minutes where it turns of in auto mode right?

Anyways would be great if others could check out the idle/standby power usuage as well.
 
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Guddu

Guddu

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This was after the 10 minutes where it turns of in auto mode right?
Yea, correct.
On Auto set, it turns off after about 10 min. The relay makes sound when turning it off.

Note that I can included 2 power utilization snapshots:
1) first one with 19.9w usage is when it’s ON but nothing is playing
2) second one with 9.5w usage when it’s off after auto-off

Anyways would be great if others could check out the idle/standby power usuage as well.
I would encourage others as well to post their observations after using these here.
 
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amix

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Ah, such a post makes me hungry. Can't wait to receive my two monos with the two 10A supplies. Will report back, that's for sure !

Still need to find a PreAmp because my old one has too little output voltage. I feel tube pres should be the best for Class-D. Ideally in class-A.
 
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Guddu

Guddu

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Can't wait to receive my two monos with the two 10A supplies. Will report back, that's for sure !
Separate power supply, I like that.
I am wondering- why 10a each, not 5a?

I feel tube pres should be the best for Class-D. Ideally in class-A.
Which one do you have in thoughts?

Me & friends tried cheap 50$.ish tube preamp and I can tell that the experience wasn’t great but it could be because that preamp wasn’t of decent quality itself.
 

lavid

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> I got 48v 10a PSU, and it is supplied with a splitter cable to connect to 2 amplifiers.
> PSU is heavy, which feels good and safer. 18 AWG cables are used by manufacturer which is good enough for 10a current (in general), details in picture below:

View attachment 366029
Did the splitter cable come with the 10A PSU option? The wording on the kickstarter+additional options page seems to read that you need to also add the splitter as a separate item.

pinging @Fosi Audio
 

Yannick

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According to posts made by Fosi Audio in the Kickstarter Comments section, the splitter cord is automatically included with the 10A power supply of any pledge for 2x V3 Mono and 1x 10A PSU.
 
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Guddu

Guddu

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Did the splitter cable come with the 10A PSU option? The wording on the kickstarter+additional options page seems to read that you need to also add the splitter as a separate item.

pinging @Fosi Audio
Yes, I think splitter cable is included as default if you order 2 amps with 1 x 10a psu
 

Brian Hall

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It looks great, but I decided to go with a single ZA3 for my office setup and moved my regular V3 to my new bedroom setup.

I wish Fosi would make a great multi-channel class D Atmos amp/AVR to replace my current living room AVR. Maybe they will in the future.
 

kemmler3D

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I fired up REW to quickly see how different is frequency response in my room at my listening position
I think any frequency response change would be unexpected, especially one as variable as you've shown here. It looks like +/-3 dB in some places which you could definitely hear on an a/b.

My first guess is the mic could have moved in between measurements - possible?
 

amix

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Separate power supply, I like that.
I am wondering- why 10a each, not 5a?

People all over the forums and also Dynaudio customer support themselves recommend high current amplifiers (in contrast to high power) for their speakers. I just heard, the chip may be current limited in such a way, that 10A won't help me, but I will see
Me & friends tried cheap 50$.ish tube preamp and I can tell that the experience wasn’t great but it could be because that preamp wasn’t of decent quality itself.
None, so far. "The British Audiophile" was very pleased with an integrated with a Hyper module, that had tubes in the pre, while he generally dislikes class d.
 

vicenzo_del_paris

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Strange, in the other thread Fosi themselves mention the supposed 0.5W standby power usage.

Isn't the 0.5w for the amplifier itself, not counting for the PSU ?
 
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Guddu

Guddu

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I think any frequency response change would be unexpected, especially one as variable as you've shown here. It looks like +/-3 dB in some places which you could definitely hear on an a/b.
Sometimes Yes.

My first guess is the mic could have moved in between measurements - possible?
mic was at the same random position, along with other settings.
 
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