Fosi v3 Mono - User Impressions | Owner's Thread

[Audiovue]

Vous avez peut-être un problème similaire au mien. J'ai passé des heures à essayer de comprendre pourquoi ma scène sonore était tirée vers le bas et vers la gauche. J'avais besoin d'un important décalage d'équilibre vers la droite et elle était toujours en pente. J'ai fini par y parvenir.

En raison de contraintes d'espace, j'ai placé mon caisson de basses juste devant le haut-parleur gauche et la surface supérieure est juste en dessous des haut-parleurs. Les réflexions de la surface supérieure déséquilibraient la scène sonore. Je peux résoudre ce problème en plaçant un matériau absorbant le son (un coussin ) sur le dessus du caisson de basses

Je ne dis pas que le vôtre est exactement le même, mais faites attention à toute asymétrie dans les surfaces/matériaux d'où peuvent provenir les reflets. Par exemple, du verre d'un côté et du bois ou du plâtre de l'autre. Un mur d'un côté, ouvert de l'autre, etc.

La pièce est votre soucis

 

[P1NBA11ER]

My V3s finally arrived late Saturday. Lots of people are talking about how hot they get but mine do not get as hot as the Monarchy Audio (now defunct I think) SM-70 "True Class A" FET based amplifiers I had been using in dual mono for around 10 years or so. I can touch them and not burn myself with them left on for a couple hours and not driving them all that hard. The Monarchy's got too hot to touch since they're basically doing all the work all the time (class A) regardless of how loud you're listening.

The Fosi's are dead quiet. I can't hear even the slightest hiss putting my ear up to the speaker at normal listening levels, which for me is around 78 - 80db measured with my iphone. I haven't bothered to try turning them up to 11 to see if I can make them make noise. The Monarchy's had an audible noise floor with my ear to the speaker.

The Fosi's sound good to me. I do think they sound a bit different than the Monarchy's. I'd call it "more." A bit more bass, a bit more highs. I might attribute this to their almost certainly measurably better specs than a mosfet based amp running in Class A. Otherwise, the Monarchy's sounded fine too. I'm happy. I wanted to save space mainly and these save a ton of that. I'll need to listen for a lot longer to see if they're relaible or over fatiguing or soemthing.

They can be driven to uncomfortably loud levels with my Schiit Kara pre using the highest gain setting on the Kara and the highest gain setting on the Classic Audio MC Pro (my listening is 100% vinyl only as I'm a collector and I like my records). At the lower gain setting on the Kara, I have to turn the preamp most of the way up to get too loud. On the passive setting, nearly all the way up which I just do not like. While I can't complain of it's sound qualities, I don't love my Schitt preamp, I find the taper of the volume control to be useful at the top half of it's range only, even at high gain settings, just to get to 78db listening levels. The Fosi's need a little bit more volume than the Monarchy's did I think which leaves me with even less precise control over the volume. 1 click ends up being quite a lot when the dial is at 66% or more and it's using some variation of a logarhythmic taper. I really think this is the problem with the Kara.

 

[EddNog]

My V3s finally arrived late Saturday. Lots of people are talking about how hot they get but mine do not get as hot as the Monarchy Audio (now defunct I think) SM-70 "True Class A" FET based amplifiers I had been using in dual mono for around 10 years or so. I can touch them and not burn myself with them left on for a couple hours and not driving them all that hard. The Monarchy's got too hot to touch since they're basically doing all the work all the time (class A) regardless of how loud you're listening.

The Fosi's are dead quiet. I can't hear even the slightest hiss putting my ear up to the speaker at normal listening levels, which for me is around 78 - 80db measured with my iphone. I haven't bothered to try turning them up to 11 to see if I can make them make noise. The Monarchy's had an audible noise floor with my ear to the speaker.

The Fosi's sound good to me. I do think they sound a bit different than the Monarchy's. I'd call it "more." A bit more bass, a bit more highs. I might attribute this to their almost certainly measurably better specs than a mosfet based amp running in Class A. Otherwise, the Monarchy's sounded fine too. I'm happy. I wanted to save space mainly and these save a ton of that. I'll need to listen for a lot longer to see if they're relaible or over fatiguing or soemthing.

They can be driven to uncomfortably loud levels with my Schiit Kara pre using the highest gain setting on the Kara and the highest gain setting on the Classic Audio MC Pro (my listening is 100% vinyl only as I'm a collector and I like my records). At the lower gain setting on the Kara, I have to turn the preamp most of the way up to get too loud. On the passive setting, nearly all the way up which I just do not like. While I can't complain of it's sound qualities, I don't love my Schitt preamp, I find the taper of the volume control to be useful at the top half of it's range only, even at high gain settings, just to get to 78db listening levels. The Fosi's need a little bit more volume than the Monarchy's did I think which leaves me with even less precise control over the volume. 1 click ends up being quite a lot when the dial is at 66% or more and it's using some variation of a logarhythmic taper. I really think this is the problem with the Kara.

What if you just ran Kara in passive mode? That would allow finer volume control, right? Or is Kara unity gain in solid state buffer mode?

-Ed

 

[P1NBA11ER]

The Kara has 3 settings... passive (zero gain, bypasses the pre-amp and provides passive resistive attenuation) and then active low & high gain selections. Not sure what the actual specs for gain are but passive mode is quieter than active low, which is quieter than active high.

 

[EddNog]

The Kara has 3 settings... passive (zero gain, bypasses the pre-amp and provides passive resistive attenuation) and then active low & high gain selections. Not sure what the actual specs for gain are but passive mode is quieter than active low, which is quieter than active high.

Okay, and you can’t find a happy place for volume control still? Interesting…I have Freya+, which also has 3 settings, but passive and solid state buffer are both unity gain (zero gain). Tube buffer mode is a big jump.

-Ed

 

[SMen]

My V3s finally arrived late Saturday. Lots of people are talking about how hot they get but mine do not get as hot as the Monarchy Audio (now defunct I think) SM-70 "True Class A" FET based amplifiers I had been using in dual mono for around 10 years or so. I can touch them and not burn myself with them left on for a couple hours and not driving them all that hard. The Monarchy's got too hot to touch since they're basically doing all the work all the time (class A) regardless of how loud you're listening.

The Fosi's are dead quiet. I can't hear even the slightest hiss putting my ear up to the speaker at normal listening levels, which for me is around 78 - 80db measured with my iphone. I haven't bothered to try turning them up to 11 to see if I can make them make noise. The Monarchy's had an audible noise floor with my ear to the speaker.

The Fosi's sound good to me. I do think they sound a bit different than the Monarchy's. I'd call it "more." A bit more bass, a bit more highs. I might attribute this to their almost certainly measurably better specs than a mosfet based amp running in Class A. Otherwise, the Monarchy's sounded fine too. I'm happy. I wanted to save space mainly and these save a ton of that. I'll need to listen for a lot longer to see if they're relaible or over fatiguing or soemthing.

They can be driven to uncomfortably loud levels with my Schiit Kara pre using the highest gain setting on the Kara and the highest gain setting on the Classic Audio MC Pro (my listening is 100% vinyl only as I'm a collector and I like my records). At the lower gain setting on the Kara, I have to turn the preamp most of the way up to get too loud. On the passive setting, nearly all the way up which I just do not like. While I can't complain of it's sound qualities, I don't love my Schitt preamp, I find the taper of the volume control to be useful at the top half of it's range only, even at high gain settings, just to get to 78db listening levels. The Fosi's need a little bit more volume than the Monarchy's did I think which leaves me with even less precise control over the volume. 1 click ends up being quite a lot when the dial is at 66% or more and it's using some variation of a logarhythmic taper. I really think this is the problem with the Kara.

Excellent ... I'm getting the MM Pro in a couple of weeks (after M. Fiedler's summer break at Classic Audio). I am wondering if you have a super low output MC? You couldn't have really inefficient speakers with those Monarchy's... I'm slightly surprised the balanced output is not driving your speakers in passive mode. My own monos are finally in transit on the French postal network so it will be a couple of days to test with my own passive volume controls. I'd be slightly 'narked' to need an additional pre-amp gain stage.

My DAC outputs 5v in balanced which should be more than enough - and my current iFi is only slightly behind with current volume control settings.

I will compare notes as and when...

 

[P1NBA11ER]

This is going to be kind of off topic I think but might be helpful in general so I'll try and continue...

It's not an issue with happy place really and I don't think it's an issue with speaker "drive". It's that the Kara has to be turned up A LOT in order to output enough signal to drive the Fosi's (or the previous amps) to what I would consider relatively comfortable listening levels. I don't listen to music particularly loud compared to many people it seems. With the volume control at 50%, passive mode is basically, a whisper. I looked up the specs and active mode 1 is indeed unity gain as is the Freya. This sounds slightly louder to me than passive mode FWIW, though I guess technically it shouldn't. The high gain mode is 4db gain. This puts the system into a more useful range with the listening level of the volume control at around 60%. I understand that this is technically "just a number." What gets tricky is if you consider a typical volume control for audio will be tapered logarithmically, the lower input sensitivity places the volume control's useful range into the steeper part of the log curve making minor adjustments far more impactful, and basically wasting the entire point of having a logarithmic curve in the first place. And I feel like my experience with the Kara matches this. Clicks once I get up into the 60% range make a pretty sizeable jump in volume, giving less precise control over the listening level. I've never had a stereo component of any sort where I needed to turn the dial much past half to be FAR too loud. I've also never used a DAC with anything other than a computer.

 

[EddNog]

This is going to be kind of off topic I think but might be helpful in general so I'll try and continue...

It's not an issue with happy place really and I don't think it's an issue with speaker "drive". It's that the Kara has to be turned up A LOT in order to output enough signal to drive the Fosi's (or the previous amps) to what I would consider relatively comfortable listening levels. I don't listen to music particularly loud compared to many people it seems. With the volume control at 50%, passive mode is basically, a whisper. I looked up the specs and active mode 1 is indeed unity gain as is the Freya. This sounds slightly louder to me than passive mode FWIW, though I guess technically it shouldn't. The high gain mode is 4db gain. This puts the system into a more useful range with the listening level of the volume control at around 60%. I understand that this is technically "just a number." What gets tricky is if you consider a typical volume control for audio will be tapered logarithmically, the lower input sensitivity places the volume control's useful range into the steeper part of the log curve making minor adjustments far more impactful, and basically wasting the entire point of having a logarithmic curve in the first place. And I feel like my experience with the Kara matches this. Clicks once I get up into the 60% range make a pretty sizeable jump in volume, giving less precise control over the listening level. I've never had a stereo component of any sort where I needed to turn the dial much past half to be FAR too loud. I've also never used a DAC with anything other than a computer.

Okay, I understand your issue better now. That’s an interesting problem…I believe my source signal is stronger to begin with (Musician Draco balanced output is 2.8V…although maybe that’s not a lot compared to a lot of modern DACs putting out 4V or even some at 5V!). Also, my Freya+’s tube buffer mode increases gain around +12db (depends on tubes used), which is a huge jump from zero, so I always have to turn volume way down before turning on tubes, or we get an unhappy event. That being said, I don’t have volume granularity issues even in passive mode. Your only solution may be a DAC with stronger output to begin with. Fortunately the market is chock full of chi-fi DACs with eleventy million SnR as tested here at ASR with quite palatable price tags.

-Ed

 

[jvdburgt]

Reading these discussions, I wonder how my Marantz SR6010, with only 1.2V out, will fare as a pre-amp to the mono's.

Sounds like I need to put the gain-switch to the 31dB position to have at least some volume

 

[EddNog]

Reading these discussions, I wonder how my Marantz SR6010, with only 1.2V out, will fare as a pre-amp to the mono's.

Sounds like I need to put the gain-switch to the 31dB position to have at least some volume

Single-ended input has much higher gain than balanced input.

Actually, @P1NBA11ER , have you tried using single-ended instead of balanced just as a test?

-Ed

 

[SMen]

This is going to be kind of off topic I think but might be helpful in general so I'll try and continue...

Okay, I understand your issue better now. That’s an interesting problem…

-Ed

@P1NBA11ER you are using the MC Pro from Classic Audio. The 73 DB gain on this with your MC cartridge should give a specific output using the balanced outputs on the phono.

I'd ask Classic Audio (or calculate ... I'm sure there is an algorithm) what the output in balanced mode from your MC cartridge should be.

I'm not sure this is so off topic... knowing what the minimum pre-amp outputs need to be with such devices. I just understand that 4v or 5v ought to be fine at zero gain to reach full volume (way way too loud). Personally I'm happy not going above 85db peaks (that's pretty loud for me).

 

[P1NBA11ER]

Single-ended input has much higher gain than balanced input.

Actually, @P1NBA11ER , have you tried using single-ended instead of balanced just as a test?

-Ed

Nope. It will be 5db higher so I would expect if would help the volume control issue for sure. I'm not sure it's worth moving from balanced for the 5db gain over the less precise control of the volume level.

 

[P1NBA11ER]

@P1NBA11ER you are using the MC Pro from Classic Audio. The 73 DB gain on this with your MC cartridge should give a specific output using the balanced outputs on the phono.

I'd ask Classic Audio (or calculate ... I'm sure there is an algorithm) what the output in balanced mode from your MC cartridge should be.

I'm not sure this is so off topic... knowing what the minimum pre-amp outputs need to be with such devices. I just understand that 4v or 5v ought to be fine at zero gain to reach full volume (way way too loud). Personally I'm happy not going above 85db peaks (that's pretty loud for me).

It's a Dynvactor 20X2 L with a spec'd output of .3mv which should yield 1.34V RMS (if my math is correct) at the output of the phono preamp with a gain of 73db on the high setting. This is pretty low actually and certainly part of the "problem" if one defines it as such.

 

[SMen]

It's a Dynvactor 20X2 L with a spec'd output of .3mv which should yield 1.34V RMS (if my math is correct) at the output of the phono preamp with a gain of 73db on the high setting. This is pretty low actually and certainly part of the "problem" if one defines it as such.

Yes, your math is better than mine, but if it is 1.34 after 73db gain, then you would be well below making full output - someone else here will know off the top of their heads ...
It is a problem to get the best out of MC's. I have an old Technics MC that is in storage since before covid ... but I have very fond memories of a dynavector high output MC.

Great cartridges (but now I am definitely off topic) ;-)

 

[SMen]

It's a Dynvactor 20X2 L with a spec'd output of .3mv which should yield 1.34V RMS (if my math is correct) at the output of the phono preamp with a gain of 73db on the high setting. This is pretty low actually and certainly part of the "problem" if one defines it as such.

Actually I have been thinking about this a bit more.

Michael Fidler makes quite a strong argument for not using balanced cables from your tonearm to the phono preamp, and your phono preamp only has unbalanced inputs for this reason.

If your turntable and MC Pro are near your Kara, I'd go unbalanced into your Kara from your MCPro. You will be bypassing the balanced circuit in your MCPro - including op amps, and philosophically still be optimizing your MC Pro. Great work is in the gain stage as far as I can tell, along with the RIAA ...

I don't know if this is different but your Kara may do better either into the balanced inputs of your Monos, or it may be just fine into the unbalanced 31db gains of your monos.

I'd be interested to know if this makes a difference.

 

[Slowloris]

Reading these discussions, I wonder how my Marantz SR6010, with only 1.2V out, will fare as a pre-amp to the mono's.

Sounds like I need to put the gain-switch to the 31dB position to have at least some volume

I am basically going to be trying them on an identical system. Will be running them into Sonus faber lumina 2's ( a forum favorite) / sarcasm. I did the preorder so I wont know until august

 

[P1NBA11ER]

Actually I have been thinking about this a bit more.

Michael Fidler makes quite a strong argument for not using balanced cables from your tonearm to the phono preamp, and your phono preamp only has unbalanced inputs for this reason.

If your turntable and MC Pro are near your Kara, I'd go unbalanced into your Kara from your MCPro. You will be bypassing the balanced circuit in your MCPro - including op amps, and philosophically still be optimizing your MC Pro. Great work is in the gain stage as far as I can tell, along with the RIAA ...

I don't know if this is different but your Kara may do better either into the balanced inputs of your Monos, or it may be just fine into the unbalanced 31db gains of your monos.

I'd be interested to know if this makes a difference.

I am indeed using plain RCA from the TT to the MC Pro but from there, I'm currently running balanced. I suppose it can't hurt to try going back to all RCA to see how much difference that makes.

 

[SMen]

I am indeed using plain RCA from the TT to the MC Pro but from there, I'm currently running balanced. I suppose it can't hurt to try going back to all RCA to see how much difference that makes.

I don't know if there is additional gain on the balanced outputs on the MC Pro off the top of my head, but yeah, can't hurt!

 

[korgua]

Almost two weeks on from my 1st post.....every day with the monos are audio heaven for me.

https://audiosciencereview.com/foru...o-v3-mono-amplifier-review.53474/post-2019325

Swapped from RCA to TRS / XLR cables, I do not have any issues with hiss / loops, I was interested in seeing if there was any other difference, other than a difference in gain. My ears have not noticed any audible difference.

I am looking at two MUSES02 chips on the shelf and would like to try them, if nothing else, to see if I prefer the sound....I thought I saw a picture of where to install them. I know the one near the RCA input does not need changing. Of the remaining two, which should be changed to effect the 'best' result......somewhere I think I read that position 2 was the first one to change....which one is that?

https://support.fosiaudio.com/hc/en-us/articles/33329687302297-The-V3-Mono-has-three-op-amps-What-does-each-one-do-And-if-l-want-to-get-abetter-sound-which-one-should-l-change

I notice in the video that for the v3 the notches in the chip face the capacitors - is this the same for the v3 mono?

https://support.fosiaudio.com/hc/en-us/articles/32538018953881-How-to-replace-the-Op-Amps-in-the-V3

Thank you.

 

[HoweSound]

I received my order yesterday - two V3 monos and two 48v/5a power supplies. They sent only one XLR cable and one opamp. Have others received pairs of cables and opamps with their order of two V3 Monos?