Fosi Audio V3 Mono Amplifier Review

[WillBrink]

Even WITH the DC filter in place, when using single-ended/RCA inputs, he still gets the noise with a single power supply feeding both amps. With balanced/XLR inputs, no noise. Probably the best path to take when implementing these amps is either don't share power supplies or only do so if using balanced inputs, and not when using single-end inputs.

-Ed

Are you not at least partially defeating the benefits of the two amps by having them share a PS?

 

[antcollinet]

Sorry if this is a stupid question, but why "at least"?

Because most modern sources can provide more than the 1.75V needed (typically 2V for RCA sources).

 

[EddNog]

Are you not at least partially defeating the benefits of the two amps by having them share a PS?

That’s how I feel about it, but apparently a decent number of people don’t care except to save money by only having to pay for one power supply and/or actually do care about the meager difference in space utilization of having a second unit.

-Ed

 

[kelesh]

I asked Fosi how to distinguish units with/out reversed phase and they sent this. Note extra QC label for units without inverted phase. My units from Amazon received Aug 20 were inverted phase.

View attachment 388556

I wonder, how long before they correct all the units already produced and then eliminate this extra step and sticker.

 

[multichannel_guy]

It looks like 2 fosi monos with two 48V 5Amp power adapters is $280
2 fosi monos with two 48V 10 Amp power adapters is $420

Are the 10 Amp adapters worth the extra $140, if running Magnepan LRS? Thanks guys.

 

[thunderchicken]

I’m getting popping from mine on power off and during volume changes. I’m using the hypex preamp, and the problem was enough to warranty the unit. Hypex replaced a board and sent it back to me. The pops have lessened but are still an issue. This still points to the preamp, but it seems to be an issue with the fosi monos as well if they do it at power off. DC is getting through but it’s not apparent from where.

 

[EddNog]

It looks like 2 fosi monos with two 48V 5Amp power adapters is $280
2 fosi monos with two 48V 10 Amp power adapters is $420

Are the 10 Amp adapters worth the extra $140, if running Magnepan LRS? Thanks guys.

My dad is using V3 Monos with his LRS+ in a decent sized room, sitting around 12’/3meters away with smaller power supplies than even 48V and is happy with it. I think you’re fine with separate 48V 5A supplies.

-Ed

 

[multichannel_guy]

My dad is using V3 Monos with his LRS+ in a decent sized room, sitting around 12’/3meters away with smaller power supplies than even 48V and is happy with it. I think you’re fine with separate 48V 5A supplies.

-Ed

What is the approximate SPL levels he is listening at the 12 feet distance?

 

[EddNog]

What is the approximate SPL levels he is listening at the 12 feet distance?

He’s pretty old school and wouldn’t know how to measure that for me. I can take a measurement next time I go up to New York, but it may be weeks away.

I can say this much: he listens louder than I do, and I’m normally around 65-70dB at my listening position only 9 feet away from my LS50 Metas.

If I had to guesstimate, 70-75dB for the old man.

-Ed

 

[courtesy]

......for the old man.

You also got to wonder how his hearing is compared to yours.

 

[EddNog]

You also got to wonder how his hearing is compared to yours.

Having worked in restaurants for over 50 years, I’m sure his hearing has seen better days, but at the same time, I know guys his age with MUCH worse hearing. Plus, he’s been into hi-fi for about 40 years, so at least he knows…how…to listen.

-Ed

 

[Sokel]

I’m getting popping from mine on power off and during volume changes. I’m using the hypex preamp, and the problem was enough to warranty the unit. Hypex replaced a board and sent it back to me. The pops have lessened but are still an issue. This still points to the preamp, but it seems to be an issue with the fosi monos as well if they do it at power off. DC is getting through but it’s not apparent from where.

Have you measured the DC on both the preamp outputs and at speakers binding posts?
Do measure it and if it's more than few mV (ideally zero,tops 50mVDC) remove the DC source ASAP from your speakers.

That's the first thing one should do with any new device,no matter if it's a DAC,a pre or an amp before connecting them to the rig,DC can kill speakers.
A DMM costs nothing comparing to other stuff of the hobby and it's useful in a gazillion of cases.

 

[courtesy]

Having worked in restaurants for over 50 years, I’m sure his hearing has seen better days, but at the same time, I know guys his age with MUCH worse hearing. Plus, he’s been into hi-fi for about 40 years, so at least he knows…how…to listen.

-Ed

Excellent...and he passed the audio bug to you.

 

[EddNog]

Excellent...and he passed the audio bug to you.

100% he really did! Although that didn't happen until much later in our lives, as I did not get into this very seriously until the past couple of years. I dabbled in headfonia for a bit a decade ago, but that was really it until I got into speaker setups starting early last year.

-Ed

 

[courtesy]

100% he really did! Although that didn't happen until much later in our lives, as I did not get into this very seriously until the past couple of years. I dabbled in headfonia for a bit a decade ago, but that was really it until I got into speaker setups starting early last year.

-Ed

I got the bug from my Dad. He was big into music. My aunt (his sister) was a well known actress and singer in Hong Kong in the late 50's-early 60's.
He spent good money on a system and various components in the early 70's, and I used them and learned what I liked. But I didn't start with my own system until I graduated college in the mid-80's.
Guess we should get back on subject.
I'm very happy with V3Monos and WiiM Ultra driving a pair of Ascend Acoustics Luna v2's. Sources are Roon and AppleTV (via a 2+ year old Visio TV using eARC).

 

[SMen]

He’s pretty old school and wouldn’t know how to measure that for me. I can take a measurement next time I go up to New York, but it may be weeks away.

I can say this much: he listens louder than I do, and I’m normally around 65-70dB at my listening position only 9 feet away from my LS50 Metas.

If I had to guesstimate, 70-75dB for the old man.

-Ed

I'm beginning to feel like your father (old) ... I can happily hit 80db ... but I'm surprised how much of my listening that I thought was loud, is actually down in the 70dbs.

I use one of these great little gadgets. Set it to max and you get a fixed value for the duration it is set to max.

Nobody talks about balance these days. Even digital recordings or broadcasts in digital can somehow get the balance wrong. Old ears (or indeed young) have imbalance.

Or whoever is in the studio handling the mix!

I wish whoever it is in the BBC studio doing the mix would get their ears tested for the sports commentary ...

Okay I appreciate that this is going to be lost on many here ... but the snooker commentary at the Crucible was much better this year ...

The "Today at the Test" cricket commentary (currently) is 1 to 1.5 db off to the right!

So what's the point of separate power supplies, and wonderful channel separation with monoblocks ... if you can't adjust the balance because someone can't hear properly in the mixing studio!

Or maybe it is just me...

 

[Bernard23]

Just joined the mono block club, single split PS. I'm only driving a pair of DBR62 albeit in a largeish room but have an active sub, paired with a Wiim Ultra and a 1977 Technics SL-1800. I'm deaf above 13kHz and plan on going more so.
I now have an obsolete Wiim Pro plus, Cambridge Alva Duo and Yamaha A-S501; 2 weeks ago I was in ignorant bliss and just getting to grips with RC with a manual sub

 

[joostdh]

Cambridge Alva Duo

Can the Ultra replace the Duo? That would be quite a feat. I bought the Monos, planing to pair them with the Ultra but haven’t bitten the bullet yet.

 

[Bernard23]

Can the Ultra replace the Duo? That would be quite a feat. I bought the Monos, planing to pair them with the Ultra but haven’t bitten the bullet yet.

Yes, it has a phono input. Means you can DSP vinyl. No idea yet how it compares, but I suspect it's perfectly OK given it's going to be digitalised before any gain. There is a phono ground terminal too, so should be good.

 

[courtesy]

Yes, it has a phono input. Means you can DSP vinyl. No idea yet how it compares, but I suspect it's perfectly OK given it's going to be digitalised before any gain. There is a phono ground terminal too, so should be good.

Honest question here as I see people very happy about the phono input...
First, I am not a vinyl guy, but why would you want digitize the beloved vinyl/analog output?