Fosi Audio's First Dual-Mode Balanced Amplifier ZA3

[jackdanyal]

Just got this little one from amazon.nl. With a 10% coupon from Amazon and a 15% coupon that I got from the Fosi website, it cost me just 110 euros with a 48v power supply. Decided to take a quick test and compare it with my Yamaha A-S301. I use Burson Play V5 as a preamp. The main reason for the purchase was the space that Yamaha required on my table. This tiny will perfectly fit under the Burson.

Iniitial impressions are:
It has a lot of power for my Heco Aurora 300. You can see it from the image, the volume control on the Fosi is on 75% position (using as a power amp), and on Burson it's just 27(out of 100, but vol level 60 gives full 2vrms power, so 27 out of 60) and it's already loud. On 35 it's crazy loud. If compared with Yamaha the sound is very detailed, involving, crispy, and crystal clear. Even at full volume, I didn't hear any hiss from the speakers (considering that they are very sensitive ones, 90Db). On Yamaha, on 50% there was a very noticable hiss from both of speakers. On Yamaha, the sound is more energetic, spacious, warm, and relaxing(of course, AB vs D class). Of course, Yamaha has much more power and it's not as clinical as the Fosi. But considering the size, weight, price - just wow. If I need to choose one of them, I still will take Yamaha, no doubt and not even because of the features, but because of the sound, but for now Fosi stays as a desktop solution, Yamaha goes to the living room with Hecos. For desktop I still don't know what to choose, Elac DBR62s or Wharfedale Diamond 12.2.

@Fosi Audio I would suggest creating a pure power amp w/o any volume control etc. I'll be the first one who will purchase it

 

[PlasticDoc]

PFFB on the TPA 3255 reduces THD+N by around 6 dB on average and up to 9dB. It has no effect on power. Spec sheet

On page 4 (Table 1. Recommended PFFB Component Values) of that Spec sheet one sees how inexpensive it is to add PFFB to a TPA3255. Say 11 components costing most of them a few cents each it would add what? 10 to 15€ more to the final product?

Also on page 4 of that Spec sheet, the recommended Zobel network is 220 nF + 1Ω, while the traditional Zobel is 100 nF + 10Ω (*).

This could help explain why this TPA3255 chip can effortlessly drive very low speaker impedances to 2Ω (and lower?)... and the need for high amperage PSUs.

This peculiar Zobel network seems to be the reason why there is a sweet spot voltage for this TPA3255 PFFB to 36V(to 39V)/10A.

The PSU voltage could be even lower than 39V, as typical room listening volumes need amplifier power from 1 W to 10 W. Yes it was no mistake, these low values are right. A 89dBW speaker can be driven pretty loud, in a home setting, with only 20W (RMS) power.

(*) In a conventional Zobel network the 10Ω resistor approximates to the expected loudspeaker load impedance and the capacitor is invariably 100 nF. The Zobel network is used to mitigate amplifier high frequency instability by preventing too inductive reactance being presented to the amplifier output by a loudspeaker voice-coil, vide "Zobel Networks" in Audio Power Amplifier Design by Douglas Self

 

[Extreme_Boky]

I had very high hopes for this one... expected an end-to-end balanced design with a minimal number of sound coupling caps along the signal path... but it seems I'll have to wait a bit longer.

Below in yellow are what appear to be the sound coupling caps. Unfortunately, what was advertised as a balanced design is confined only to a green square... what a shame.

 

[GNK]

Below in yellow are what appear to be the sound coupling caps. Unfortunately, what was advertised as a balanced design is confined only to a green square... what a shame.

Thanks for your info, I could cancel my order before it was shipped.

 

[Yorkshire Mouth]

We're going to add the adjustable high pass filter in another model. It won't introduce distortion.

Hi, Fosi Audio.

When are you expecting to release this ‘other model’?

Many thanks.

 

[Meloman]

I see on V3 warmer sound than on ZA3. I think if I need only amplifier without other features I prefer V3.

 

[Glades]

I got a good deal on the ZA3, however, knowing what I know now, I would pay happily the full price. So I did and ordered a second one for a dual mono setup. My office gear is a WiiM mini, connected to a MiniDSP Flex and Audiolab 6000a. Speakers are Wharfedale Lintons.
The Audiolab is nice, but at higher volumes it runs a bit out of steam. Being a sceptic, I couldn't believe the ZA3 would outperform the Audiolab. Well, it did and with flying colors. It will run the Lintons loud(er), with a clean deep bass and detailed mids and top end, but never sybilant. I guess the ZA3 pairs quite well with the Lintons. Dirac Live enhanced it further, so can't wait for the second ZA3

 

[CamRector]

@Fosi Audio congrats on the day 1 sell out! Well deserved!!

Many great suggestions here. I’m a firm believer in less is more.
My suggestions:
2 seperate versions (Stereo and Mono)
Balanced Xlr and rca inputs on both
Ditch the volume control
Ditch the sub out
Implement PFFB
48v 5a
$150

Win the audio game

 

[K.Kevin]

@Fosi Audio congrats on the day 1 sell out! Well deserved!!

Many great suggestions here. I’m a firm believer in less is more.
My suggestions:
2 seperate versions (Stereo and Mono)
Balanced Xlr and rca inputs on both
Ditch the volume control
Ditch the sub out
Implement PFFB
48v 5a
$150

Win the audio game

Why bother creating two separate stereo and mono versions? That would increase their production costs and simultaneously cut their market in half for each of those products. It would make no sense when a toggle switch for stereo/mono can already cover 100% of customers’ needs.

The other suggestions I would support

 

[CamRector]

Why bother creating two separate stereo and mono versions? That would increase their production costs and simultaneously cut their market in half for each of those products. It would make no sense when a toggle switch for stereo/mono can already cover 100% of customers’ needs.

The other suggestions I would support

Because toggle switches are ugly and unused inputs are a waste. They wouldn’t cut their market in half. They would own the entire $500 and below market!
Possible $1000 and below.
Hell fix the load dependence and I can’t really see a reason to buy Purifi/Hypex.

 

[K.Kevin]

Because toggle switches are ugly and unused inputs are a waste. They wouldn’t cut their market in half. They would own the entire $500 and below market!
Possible $1000 and below.
Hell fix the load dependence and I can’t really see a reason to buy Purifi/Hypex.

Oh I see, another unhealthy OCD post

 

[Joe Smith]

@Fosi Audio congrats on the day 1 sell out! Well deserved!!

Many great suggestions here. I’m a firm believer in less is more.
My suggestions:
2 seperate versions (Stereo and Mono)
Balanced Xlr and rca inputs on both
Ditch the volume control
Ditch the sub out
Implement PFFB
48v 5a
$150

Win the audio game

I hope Fosi will do this too. And make a nice control preamp that competes with the feature set of the Schiit Saga, but for a lower cost.

 

[CamRector]

Oh I see, another unhealthy OCD post

Putting useless features all over a device seems more OCD to me. ‍

 

[surroundman]

Hide the mono/stereo button somewhere else and put a dedicated on/off button. Everything else is perfect. The SUB-OUT to me is a must have. From this point on, I would never consider buying an amp without a volume controlled sub-out.

 

[CamRector]

Hide the mono/stereo button somewhere else and put a dedicated on/off button. Everything else is perfect. The SUB-OUT to me is a must have. From this point on, I would never consider buying an amp without a volume controlled sub-out.

my point is to get rid of the “integrated” aspect of this and focus more strictly on a power amp. It’s almost 2024 and if you’re not bi/triamping and utilizing DRC, you are way way behind.
These amps are almost the perfect modern solution. Almost

 

[K.Kevin]

Putting useless features all over a device seems more OCD to me. ‍

What you are asking for is for a company to make two completely separate skus, have two separate cases, boxes, manuals, marketing materials, space in their warehouse, etc. all because “unused inputs are a waste”, as if everything else I listed isn’t? Two separate products and resources invested all because the people who need a mono amp have no use for the stereo output, and the people with the stereo needs have no use for a mono function.

I don’t know about you, but I consider that the definition of unreasonable, because a simple button or switch can absolutely solve the issue for each of the two types of customers. Why go to the depths of the earth just to satiate someone’s OCD? Because I don’t think “it looks ugly” should really be the deciding factor either (when it doesn’t need to be placed in the front).

I would rather businesses like Fosi.. stay in business, rather than make silly business decisions satisfying people who cannot handle the impurity of a switch being unused on their device.

 

[CamRector]

What you are asking for is for a company to make two completely separate skus, have two separate cases, boxes, manuals, marketing materials, space in their warehouse, etc. all because “unused inputs are a waste”, as if everything else I listed isn’t? Two separate products and resources invested all because the people who need a mono amp have no use for the stereo output, and the people with the stereo needs have no use for a mono function.

I don’t know about you, but I consider that the definition of unreasonable, because a simple button or switch can absolutely solve the issue for each of the two types of customers. Why go to the depths of the earth just to satiate someone’s OCD? Because I don’t think “it looks ugly” should really be the deciding factor either (when it doesn’t need to be placed in the front).

I would rather businesses like Fosi.. stay in business, rather than make silly business decisions satisfying people who cannot handle the impurity of a switch being unused on their device.

I really don’t think you understand the free market brother. And I think you have a warped sense of what’s OCD.
Cavemen put stick figures on walls, but i guess that wasn’t good enough for Michelangelo’s OCD.
Does McDonald’s have just one burger? Ford just one car model?
Lol how many devices does Fosi have currently? How many amps? 5? 7? How many manuals and resources invested into products that no one gives a rats ass about. Did you even know about this companies existence before the v3?
Why is it called the v3? lol
Maybe cause v1 and v2 sucked. Thankfully someone at Fosi has OCD.

 

[CamRector]

What you are asking for is for a company to make two completely separate skus, have two separate cases, boxes, manuals, marketing materials, space in their warehouse, etc. all because “unused inputs are a waste”, as if everything else I listed isn’t? Two separate products and resources invested all because the people who need a mono amp have no use for the stereo output, and the people with the stereo needs have no use for a mono function.

I don’t know about you, but I consider that the definition of unreasonable, because a simple button or switch can absolutely solve the issue for each of the two types of customers. Why go to the depths of the earth just to satiate someone’s OCD? Because I don’t think “it looks ugly” should really be the deciding factor either (when it doesn’t need to be placed in the front).

I would rather businesses like Fosi.. stay in business, rather than make silly business decisions satisfying people who cannot handle the impurity of a switch being unused on their device.

Lastly you must realize that Purifi, Hypex, Icepower, Orchard etc etc ALL do this.
It’s common place in the class d world to offer a mono version and a stereo version.
Fosi would be the very first AND ONLY company to compete with these legends, sub $1000!

 

[K.Kevin]

I really don’t think you understand the free market brother. And I think you have a warped sense of what’s OCD.
Cavemen put stick figures on walls, but i guess that wasn’t good enough for Michelangelo’s OCD.
Does McDonald’s have just one burger? Ford just one car model?
Lol how many devices does Fosi have currently? How many amps? 5? 7? How many manuals and resources invested into products that no one gives a rats ass about. Did you even know about this companies existence before the v3?
Why is it called the v3? lol
Maybe cause v1 and v2 sucked. Thankfully someone at Fosi has OCD.

OCD is being bothered by a switch that you will set once and leave there for the rest of your use. OCD is being bothered by it both because of how it looks and being bothered that it is a useless feature for a minority of people using it.

When you can't look past yourself, and be at peace at a feature going unused on your device, or you think that a little switch like the ZA3 ruins its aesthetic, that is textbook OCD.

You say Fosi has 5/7 amps, you want them to have more? How many do you want them to have? 100? One amp for every percentile of user, to satisfy their eccentricities?

It's okay, I treat OCD very seriously. I have it in some other aspects of my life too. But too many times on ASR people have no self-awareness of their OCD. When it starts to manifest itself in what I consider to be incredibly unsatiable and nitpicky "suggestions", ones that muddy waters with "noise" amongst genuinely significant audible improvements suggestions, that's when I counter back on here.

Regarding your second post

You say Purifi and Hypex as examples have mono and stereo versions. Afaik they sell modules, not fully furnished finished retail amplifiers. Companies can create mono and stereo versions, sure, but who has to be beholden to who here? Your point here is very weak overall. Maybe those companies ought to unify their product to be able to have a mono and stereo switch so that they could satisfy the needs of both sets of customers...

A company like Fosi could still compete with those sub 1k "legends" with such a switch. It won't be the presence of a switch that will exclude them from doing so.

 

[CamRector]

OCD is being bothered by a switch that you will set once and leave there for the rest of your use. OCD is being bothered by it both because of how it looks and being bothered that it is a useless feature for a minority of people using it.

When you can't look past yourself, and be at peace at a feature going unused on your device, or you think that a little switch like the ZA3 ruins its aesthetic, that is textbook OCD.

You say Fosi has 5/7 amps, you want them to have more? How many do you want them to have? 100? One amp for every percentile of user, to satisfy their eccentricities?

It's okay, I treat OCD very seriously. I have it in some other aspects of my life too. But too many times on ASR people have no self-awareness of their OCD. When it starts to manifest itself in what I consider to be incredibly unsatiable and nitpicky "suggestions", ones that add noise to genuinely significant audible improvements, that's when I counter back on here.

Regarding your second post

You say Purifi and Hypex as examples have mono and stereo versions. Afaik they sell modules, not fully furnished finished retail amplifiers. Companies can create mono and stereo versions, sure, but who has to be beholden to who here? Your point here is very weak overall. Maybe those companies ought to unify their product to be able to have a mono and stereo switch so that they could satisfy the needs of both sets of customers...

A company like Fosi could still compete with those sub 1k "legends" with such a switch. It won't be the presence of a switch that will exclude them from doing so.

Yup you are completely correct my mistake. You have now convinced me that the toggle switch is a modern miracle and a sight to behold! The world needs more toggle switches! Toggle switches everywhere for me and Gygess! If a device doesn’t have at least 3 toggle switch’s it should not even be considered on ASR!!
I hope every company is listening that we want toggle switches!!