Fosi Audio's First Dual-Mode Balanced Amplifier ZA3

[Guddu]

on the a07 max the monoblock switch is a tiny slider tab you need a toothpick to operate

I will receive mine today, I had and still have high hopes from it. But keeping mono/stereo switch at the back is good design choice.

also as far as fully balanced... if you look at the board pics it looks very similar to the older design so one might assume its not fully balanced but i dont think it matters

I am trying to find this because it matters to me. Ideally I would not like to connect balanced out (~4V) to XLR/TRS input which isn't balanced.
On the other hand, positive side is that if it is balanced then you get all the benefits of balanced design for lowest available price. I am trusting Fosi and being optimistic

On the other hand, why would you pick to have XLRs if single ended design, another set of RCA would have been more logical choice I think.
But anyways, there might be other benefits of it that I am not aware of and that's why seeking more information here.

 

[mike70]

It would be nice to have a bypass switch to use it with an external preamp.
With that integrated power on / volume pot you need to power on the amp and then to set the volume at max.

Maybe you can left the pot at max position and use the switch at the power strip to power on / off ... that method can be safe?

 

[GGroch]

Maybe you can left the pot at max position and use the switch at the power strip to power on / off ... that method can be safe?

Yes, with two amps in mono or one amp in stereo mode you could do that, it should be electronically safe. It is then like a lot of pure power amps that have no volume control. You could leave the volume knob at any level, but all the way up may be best so that if your kid or cat changes it you can get back to the correct level easily.

However:
- As was mentioned earlier, if the rear "Sub Out" remains on even when the amp is powered off, a powered sub would still be subbing. You of course could put your amp, preamp, and subs all on smart power switches.

- Its not convenient unless your source has a volume control or you have a pre-amp.

 

[Colonel7]

A couple of these for the mids and tweeters on active 3-way designs would be great. I second @GGroch recommendations

 

[TikBLang]

I agree with the switch from Stereo to Mono (Bridged). Fosi can use a slide switch where you will need your nail, a coin, or a flat screwdriver to slide it up and down near the mono RCA plugs and above the 'sub' out. You can do the same with the XLR-to-RCA switch, It can be mounted on the left of the XLR input near the left edge of the chassis. (I believe they are inexpensive- Just like those red 'flushed ' switches of the PC ATX power supplies.(- don't make it red - but match the color of your vent holes on the side which is bronze). And, if the design is enjoyable to look at because it is beautifully simple (clean front panel), I'm pretty sure people will be tempted to buy two instead of one. I am new in audio and this particular device is one of my wish lists this coming holiday season.

 

[Music1969]

@Fosi Audio what is the gain?

 

[Kevin T]

Greetings! We're happy to share with ASR members that our first dual-mode balanced amplifier ZA3 is about to be released! Here are some details about this amp.

•Mode: Stereo, Mono
•Input: RCA, XLR
•Output: Speaker Out, Sub Out
•Amp Chip: Texas Instrument TPA3255
•SINAD: 88dB
•SNR: ≥106dB
•Dynamic Range: ≥106dB
•THD: <0.005%
•Terminating Impedance: 2-8Ω
•Rated Output Power(1kHz, 1% THD):
•Stereo Mode: 180W*2 @4Ω
•Mono Mode: 240W @4Ω
•Frequency Response: 20Hz-20kHz (±0.1dB)
•Power Input: DC 24V-48V

This amazing amp will be officially released and available for sale in December. Before that, we will keep optimizing its performance. If you're interested in this amp you can back us on Kickstarter
https://www.kickstarter.com/project...za3-hifi-stereo-mono-balanced-power-amplifier


Of course, we're looking for any advice you have on this amp too!

Looks to be a fantastic successor to the V3! Love the balanced inputs and the ability to run in mono. I'm curious, will RMS power scale with more powerful power supplies? IE, could we expect to see more power with say, a 48v 10a power supply? Thank you and kudos again for what looks to be an incredible value.

 

[NoMoFoNo]

I may have misinterpreted but on the Kickstarter site for this new amp, a Fosi rep indicated that the sub-out on this offering will turn on and off with the power knob and be controlled by the volume control. No indication of high-pass for the mains when sub is attached though. Still, an improvement over the aux-out on the V3.

 

[mike70]

The thing that will bring Fosi to the next level will be filtering, allowing flat and load-independent frequency response. That's where the value prospect meets the objective performance sweet spot. Many of the posts I see in forums about Aiyima and Fosi chip amps include negative comments about the load dependence. Now, for many/most of us, that issue exists on testing but isn't an audible concern, BUT it holds these amps back in the collective 'hive mind'.

I've seen that comments and i don't have the technical knowledge / background in electronics ... i understand that the problem happens in HF last octave (more or less) and with "higher impedances" (above 4 ohms).

Do you know what is the practical consequence about it? which speakers would fit better for this amp? (obviously i don't mean a brand / model, i mean about technical aspects)

 

[NoMoFoNo]

I've seen that comments and i don't have the technical knowledge / background in electronics ... i understand that the problem happens in HF last octave (more or less) and with "higher impedances" (above 4 ohms).

Do you know what is the practical consequence about it? which speakers would fit better for this amp? (obviously i don't mean a brand / model, i mean about technical aspects)

I personally doubt that the rise in HF makes an audible difference BUT it allows for those focusing on objective performance to complain about the fundamentals of these devices. If the folks at Fosi and Aiyima can improve this aspect it will silence those critics and make these small amps more widely accepted IMO. Personally, I have no problem with the performance of the V3 as it is right now and can scarcely believe what a great value it presents.

 

[carpman]

Just wanted to check the Fosi ZA3 will do the following and feed a headphone amp via 3.5mm "sub" output. Is the SUB Out an AUX Out , or is it doing something to the signal? I'm hoping is will work when powered off, so I can use my headphone amp without powering on the ZA3. Would that be possible?

This kind of this:

C.

 

[ethangab]

small tiny switch for mono/stereo should be place at the back, a tiny slider type of switch. produce a variant with no volume control , with power switch at the back panel.

 

[TikBLang]

small tiny switch for mono/stereo should be place at the back, a tiny slider type of switch. produce a variant with no volume control , with power switch at the back panel.

And also the 'balance' XLR to RCA is only selected one time. why it is in the front with a dollar toggle switch? I think you guys can shave another 50 cents if you put a tiny copper-colored slider switch and place them in between the connectors.

 

[TikBLang]

Just wanted to check the Fosi ZA3 will do the following and feed a headphone amp via 3.5mm "sub" output. Is the SUB Out an AUX Out , or is it doing something to the signal? I'm hoping is will work when powered off, so I can use my headphone amp without powering on the ZA3. Would that be possible?

This kind of this:
View attachment 319923
C.

I hear your bro.. I (me) also like it if the aux out can feed another amplifier and the sound can be adjusted with the same bronze pot.

 

[GGroch]

Just wanted to check the Fosi ZA3 will do the following and feed a headphone amp via 3.5mm "sub" output. Is the SUB Out an AUX Out , or is it doing something to the signal? I'm hoping is will work when powered off, so I can use my headphone amp without powering on the ZA3. Would that be possible?

This kind of this:
View attachment 319923
C.

Fosi says on the Kickstarter Page Comments that this is not how it works. Quote: The sub-out is controlled by the power/volumes knob. So the signal is not getting passed.

The original Fosi V3 works the way you describe, and most of us do not like that because we want the V3 volume knob to also control the aux out/sub out volume.

In your diagram, simply putting some RCA Y adapters on your Source Analog Line Outputs would accomplish exactly what you want with the ZA3, but would leave variable power switch controlled Sub/Aux out for the rest of us.

 

[carpman]

Quote: The sub-out is controlled by the power/volumes knob. So the signal is not getting passed.

[...] but would leave variable power switch controlled Sub/Aux out for the rest of us.

Thanks. Yes, I get that people want the volume control to control the sub out -- I would want the same really. The only thing I'd like Fosi to do with their ZA3 is to have a switch to turn the low pass filter on or off - so if people want to pass the volume controlled signal to another device (unadulterated - as a kind of volume controlled AUX out) they could. Maybe a minority opinion.

Cheers,
C.

 

[GGroch]

.....The only thing I'd like Fosi to do with their ZA3 is to have a switch to turn the low pass filter on or off - so if people want to pass the volume controlled signal to another device (unadulterated - as a kind of volume controlled AUX out) they could. Maybe a minority opinion....

Setting the ZA3 Sub Out cut off 300Hz is an odd choice I think. Too high a frequency limit for anything but a small sub/satellite system. I do not see those systems needing dual monoblock amps. A full range volume controlled Aux Out makes more sense for the majority of users.

If they move the Mono/Stereo switch to the back, perhaps they could put a low pass switch in its place on the front. Full Range/80Hz/150Hz perhaps.

 

[carpman]

I agree 100%.

 

[TonyJZX]

to me it you had to have fixed then you need a switch to turn on sub 80hz and main speaker 80hz cut off right?

this is how you would do it... like anything else makes no sense

either do this and dont bother with a sub output... in that case i would fall back onto my preamp/processor

 

[Guddu]

In your diagram, simply putting some RCA Y adapters on your Source Analog Line Outputs would accomplish exactly what you want with the ZA3, but would leave variable power switch controlled Sub/Aux out for the rest of us.

Will it not split the 2v input resulting weak input?