Fosi ZA3 TPA3255 Mono/Stereo Switchable Amplifier, and vs Aiyima A07 Max - Quick Evaluation

[guddu478]

ZA3 amplifier - Quick visual inspection, and contents
* came in decent packaging, bigger than other Fosi amplifiers
* ZA3 amplifier, 48v 5a PSU, Manual
* Manual has all the basic information needed for connectivity

* ZA3 Amplifier Case & Construction
- Beautiful case, Orange volume knob like V3
- Slightly bigger than other TPA3255 amplifiers, quite a refreshing look
- Simple elegant look, don't think anyone would like to hide this amplifier
* PSU - Feels good build PSU
* Front
- ON/OFF and Volume Control Knob - Press and hold for ON/OFF
- Mono/Stereo Toggle switch
- RCA/XLR Toggle switch
* Back
- RCA Input: Single ended RCA input
- XLR/TRS: Balanced input accepts XLR as well as 1/4 TRS [@Fosi Audio It is really worth mentioning on product pages that ZA3 accepts 1/4 TRS balanced input, currently its XLR only everywhere]
- Sub Out: note: you will need to manage cut off frequency on the subwoofer itself
- 12v Tigger input
- Speaker Binding posts: Just like other Fosi amplifiers, small speaker connector binding posts. This is something Fosi could improve after V3 [Note: Plan to use 4mm banana plugs for safer and easy connection, there isn't enough space for spades or anything else]
- DC input jack, 24 - 48v PSU accepted: 5.5 x 2.1/2.5 mm connector

From: https://www.kickstarter.com/project...za3-hifi-stereo-mono-balanced-power-amplifier

My setup
Laptop >> Topping E50 DAC >> RCA & XLR to amplifiers >> Elac DBR62 speakers

Quick observations after powering UP and in-operation:
- With 48v 5a PSU, my ZA3 didn't even get warm. It ran very cool even after pushing to 84-86 db (from 3.5 - 4 meters).
- Idle power (powered ON but no music playing) remains around 8W
- Power ON/OFF, changing RCA/XLR makes click/relay-type sound
- Volume knob makes smooth volume transition
- Power ON/OF operation is push and hold sequence, don't need to change the volume knob position (thankfully) and so you don't loose volume level adjustment
- RCA and XLR inputs have different output levels, by SPL app showed around 5 db difference XLR being higher and RCA being lower

PE:
Sub-Out
- worked every time without any issues
- Volume knob controls sub pre-out level as well
- Only works when amplifier is powered ON

Quick listening with the setup mentioned above
- Sounds clean, powerful and good stereo separation
- ZA3 had no issues to make Elac DBR62 sing powerful
- 48v PSU makes you feel the power, if you are coming after other TPA3255 amps with 32v or 36v PSU
----------
***You can surely use the following comments as some pointers or completely ignore the following comments as its very subjective to my setup, in-room response and my taste:
- In my setup, time after time and track after track I kept of noticing slightly more punchier sound than my current regular amplifiers - Topping PA7 & Aiyima A07 Max.
All the recent Aiyima & Fosi TPS325x amplifiers measurements have shown flat response, at least up to 5-10K, and I am wondering why it felts like everything is slightly elevated (specially bass) in my setup/room with ZA3 while A07 Max and Topping PA7 don't. Its too bad that I don't have any way to measure.
- For me it's quite similar to SMSL SDB mode type sound, or loudness mode in traditional integrated amplifiers
- It surely has its own advantages, those who have heard SMSL SDB or loudness mode will be able to corelate easily, I hope
- It makes music listenable on low to moderate levels without feeling something is missing, but then it was a bit difficult for me to listen beyond 85-87 db
- Pls note that this could just be my room's response to this setup, rather than amplifier
- MusicBee 15 band EQ, lowering down 80 and 125 Hz a bit reduced/removed this loudness in my setup, but I liked it as it is
----------
Overall, It has everything to like. Its amazing for me that it is running cool while my other amps are at least warm to touch with similar output levels. PA7 even runs hotter all the time.

Mono mode
- Front toggle to select mono/stereo
- RIGHT channel input and speaker output becomes ACTIVE in Mono mode
- I honestly don't know yet how it operates internally in mono, but seems like LEFT channel shuts down.
- Without changing anything in setup like same connections and same volume knob position in Mono mode, volume level/SPL was similar or marginally higher based on SPL app on iPhone. I will check it once again as I expect higher SPL
- Note: Amplifier does not show which input has Mono operation on the back panel, but it shows Mono Speaker output on RICHT channel binding post.
- I only have one unit and so did not test dual mono setup and operation, however it should work as expected


Some Comparisons
-----------------------

Power Supply

Fosi ZA3 vs Aiyima A07

	Fosi ZA3	Aiyima A07 Max
Summary	Stereo Amplifier with balanced and unbalanced inputs + Nicer looking case + Power ON/OFF is Volume knob push and hold sequence, volume re-adjustment isn't an issue after ON/OFF as it can remain same + Runs cooler than others even with 48v PSU + 63v smoothing caps, ideal for 48v PSU + + Balanced input, more importantly an additional input + Balanced input accepts XLR as well as 1/4 TRS ++ 12v trigger input + Dedicated sub out, but no cut of freq. mgmt on amp, cab be used with an active subwoofer only ~ Speaker binding posts and spacing is tight, limits the compatibility with various bare wire gauges, spades, etc. Sound: My setup and impression: Clean and punchy. You may ignore this as well.	Stereo Amplifier with unbalanced inputs + Case feels stronger ~ Power ON/OFF requires volume knob tuen down all the way, so volume re-adjustment requires everytime it is turned ON/OFF ~ Runs slightly warm with Aiyima 36v PSU + Runs cooler (or barely warm) like Fosi ZA3 with Fosi 48v PSU ~ 50v smoothing caps, although I have had no issues with 48v PSU but many would be skeptical about 48v PSU with this amplifier + Aux or line out, can be used with an active subwoofer with RCA input, and/or stereo signal input to another amplifier + Better binding posts with adequate spacing, no issues in using thicker wires or spades Sound: My Setup and impression: Clean, balanced, non-fatiguing. You may ignore this as well.
Case size & appearance	Bigger than A07 Max Nicer looking case, feels premium for the price	Smaller than Fosi ZA3, but feels stronger Nice looking case
Output Power (Stereo)	Similar or close enough with same spec PSU	Similar or close enough with same spec PSU
Front Panel	Power On/Off + Volume Control Knob Power LED, orange/amber color, bright Mono/Stereo Toggle Switch RCA/XLR Toggle Switch	Power On/Off + Volume Control Knob, blue, brighter LED showing Power ON with Stereo or Mono Mode
Back Panel	RCA input XLR/1/4 TRS balanced input Speaker binding posts, slightly smaller and cramped LFE type single port sub-out 12v trigger input DC input jack, 5.5 x 2.1/2.5 mm connector	RCA input Speaker binding posts, better quality and placement (very similar to Topping PA7/7 plus) 3.5mm AUX or Line Out DC input jack, 5.5 x 2.1/2.5 mm connector
Air Vents	On both sides no vents on top plate	On both sides no vents on top plate
Any issues observed, or things to be aware of	So far: 1) RCA/XLR switching did not work a few times until I powered ON/OFF 2) RCA/XLR volume output levels are different, 5db observed with SOL app on iPhone	Nothing really, other than slight warmer case when in operation
Pop Out Noise on Power ON/Off operation, or with 12v Triger	Yes, it's faint but you can hear it when amplifier is powered ON/Off Same is the case with 12v Trigger	Almost negligibly faint, not an issue at all

 

[arunlouie]

More details on the sound would be great to hear from you.

 

[dafreaking]

Great writeup. I wonder why none of these type of amps that have a subwoofer output actually have any highpass/lowpass filters. A big miss

 

[Dinesh Menon]

That's a detailed review.
It seems you are more active in the ASR forum. You are a much sought after member there, also interacting with the amp manufacturers and giving them suggestions to improve.
I am a newbie both here and there.
Now ASR forum is agog with Fosi V3 Mono, after Amir Sir's recommendation.
Do you feel Loxjie A40 is missing the attention ? it seems to be an improvement on their highly recommended A30.

 

[guddu478]

Great writeup. I wonder why none of these type of amps that have a subwoofer output actually have any highpass/lowpass filters. A big miss

You are right, they both miss true LPF and HPF.
I think its more on the application and targeted audience.
* Aiyima A07 Max has "aux out" which is not only specific to subwoofer, I would say it is quite flexible for different used cases:
- connecting to another amplifier for multi-channel stereo
- connecting to a subwoofer amplifier
- connecting to an active subwoofer with line level input i.e., RCA R+L input, mostly all of those have a means to setup cut-off or roll-of freq.
- connecting to an active subwoofer with LFE input, even though its not purely LFE, i.e., single RCA input, mostly all of those have a means to setup cut-off or roll-of freq.

* Fosi ZA3 has dedicated "sub out", meant for sub-woofers only
- Fosi mentioned in some post that it has 20-300 Hz cut-off, however some measurements shows its 200Hz.

 

[guddu478]

That's a detailed review.
It seems you are more active in the ASR forum. You are a much sought after member there, also interacting with the amp manufacturers and giving them suggestions to improve.
I am a newbie both here and there.
Now ASR forum is agog with Fosi V3 Mono, after Amir Sir's recommendation.
Do you feel Loxjie A40 is missing the attention ? it seems to be an improvement on their highly recommended A30.

You are right, I am more active on ASR at the moment. I am now going to start posting on HFV as well to share product info, reviews, feedback and used cases hoping it helps to wider community. And I do interact with a few manufacturers for testing/evaluating new products as and when time permits.

Fosi v3 mono - Amir's measurements shows great results, and I hope user level testing and reviews would be great too. It seems to have great potential for a PFFB monoblock.

About Loxjie A40 (uses Infineon MA5332MS) - It is surely missing some attention, and this true for other Infineon chip based amplifiers as well. A40 looks a decent all-in-one amplifier in first look, it surely misses some features (like many other amplifiers) but there is great audience for such a product.
I have myself tested SMSL AO200 for good amount of time which is based on Infineon MA12070 chip, and found it better than many other amplifiers in many aspects if running under about 30-40W power limit with 8 & 6 Ohm speakers. However I found it responding a bit not-so-desired with 4 ohm load.
The new SMSL AO200 MKII uses Infineon MA5332, like Loxjie A40, and I guess the reason for change is something better in new chip than just availability issues.
Somehow TPA3251/3255 amplifier chips are found more used and well researched/implemented, specially its ability to do much much better with PFFB implementations, probably is reason why Infineon are somehow lacking the attention.

I wish if I had some hands-on experience with Loxjie A40 or another Infineon MA5332MS based amplifier to say any more based on real exposure than just details published by manufacturer.

On the other hand, I am in the process of testing an interesting all-in-one TPA3255 amplifier - "O-Noorus D3" which has built-in DAC (Optical & USB, AUX inputs, no ARC though), digital volume control, tone control with bypass options and remote control. This unit might fill the gap for many.

 

[guddu478]

More details on the sound would be great to hear from you.

Wondering what details would that be w.r.t. sound, can you elaborate if you are looking for anything specific?

Let me add that, both the amplifiers I mentioned have fairly flat frequency response up to 5-10K however the overall sound impression comes out with other factors like available power output on different complex loads (speaker reaction) for different freq., room mode, etc.

 

[arunlouie]

Wondering what details would that be w.r.t. sound, can you elaborate if you are looking for anything specific?

Let me add that, both the amplifiers I mentioned have fairly flat frequency response up to 5-10K however the overall sound impression comes out with other factors like available power output on different complex loads (speaker reaction) for different freq., room mode, etc.

Detailing more on what you mentioned "Clean and punchy. " vs " Clean, balanced, non-fatiguing". Like more explained on how lows, mids & highs in each, how is on soundstage etc.,

 

[Dinesh Menon]

You are right, I am more active on ASR at the moment. I am now going to start posting on HFV as well to share product info, reviews, feedback and used cases hoping it helps to wider community. And I do interact with a few manufacturers for testing/evaluating new products as and when time permits.

Fosi v3 mono - Amir's measurements shows great results, and I hope user level testing and reviews would be great too. It seems to have great potential for a PFFB monoblock.

About Loxjie A40 (uses Infineon MA5332MS) - It is surely missing some attention, and this true for other Infineon chip based amplifiers as well. A40 looks a decent all-in-one amplifier in first look, it surely misses some features (like many other amplifiers) but there is great audience for such a product.
I have myself tested SMSL AO200 for good amount of time which is based on Infineon MA12070 chip, and found it better than many other amplifiers in many aspects if running under about 30-40W power limit with 8 & 6 Ohm speakers. However I found it responding a bit not-so-desired with 4 ohm load.
The new SMSL AO200 MKII uses Infineon MA5332, like Loxjie A40, and I guess the reason for change is something better in new chip than just availability issues.
Somehow TPA3251/3255 amplifier chips are found more used and well researched/implemented, specially its ability to do much much better with PFFB implementations, probably is reason why Infineon are somehow lacking the attention.

I wish if I had some hands-on experience with Loxjie A40 or another Infineon MA5332MS based amplifier to say any more based on real exposure than just details published by manufacturer.

On the other hand, I am in the process of testing an interesting all-in-one TPA3255 amplifier - "O-Noorus D3" which has built-in DAC (Optical & USB, AUX inputs, no ARC though), digital volume control, tone control with bypass options and remote control. This unit might fill the gap for many.

I read your ASR posts on O-Noorus D series amps. You are into so many amps.
TPA3255 seems to be the common chip for so many well rated amps. So it's tried, tested & trusted.
TI states it as : 315-W Stereo, 600-W Mono PurePath Ultra-HD
So they've refined the Class-D amps.
Still Class-AB is more popular in our country.

 

[guddu478]

TPA3255 seems to be the common chip for so many well rated amps. So it's tried, tested & trusted.
TI states it as : 315-W Stereo, 600-W Mono PurePath Ultra-HD
So they've refined the Class-D amps.

TI (Texas Instruments) have been doing amazing documentation on their products in general. But they have gone a step further in explaining topologies, components and application to determine different possible output or outcomes for audio amplification chips.
They have even provided Evaluation Boards or Modules to see how good it gets, and these boards were always better TBH.
Asian manufacturers have been doing quite ordinary deployment producing cheap boards/topologies to suit their market, in the past.

I read your ASR posts on O-Noorus D series amps. You are into so many amps.

Looking at the PCB for D3 (non PFFB) and D1 (PFFB), I think O-Noorus amps are as good as others but they are packed with so many features without premium price.

Still Class-AB is more popular in our country.

True, and that's everywhere in reality. There are several great AB options, and if someone isn't bothered with a few WATTs of wasted energy then no harm in picking those.

---------------
PE.
About - "TI states it as : 315-W Stereo, 600-W Mono PurePath Ultra-HD

You already know that its the stats for the TPA3255 chip from manufacturer, but realistically the finished amplifiers aren't build to provide that much.

 

[guddu478]

Detailing more on what you mentioned "Clean and punchy. " vs " Clean, balanced, non-fatiguing". Like more explained on how lows, mids & highs in each, how is on soundstage etc.,

Let me pls get back to you with an audio recording in some time, only to help myself put some facts along with my words.

 

[Dinesh Menon]

TI (Texas Instruments) have been doing amazing documentation on their products in general. But they have gone a step further in explaining topologies, components and application to determine different possible output or outcomes for audio amplification chips.
They have even provided Evaluation Boards or Modules to see how good it gets, and these boards were always better TBH.
Asian manufacturers have been doing quite ordinary deployment producing cheap boards/topologies to suit their market, in the past.


Looking at the PCB for D3 (non PFFB) and D1 (PFFB), I think O-Noorus amps are as good as others but they are packed with so many features without premium price.


True, and that's everywhere in reality. There are several great AB options, and if someone isn't bothered with a few WATTs of wasted energy then no harm in picking those.

---------------
PE.
About - "TI states it as : 315-W Stereo, 600-W Mono PurePath Ultra-HD

You already know that its the stats for the TPA3255 chip from manufacturer, but realistically the finished amplifiers aren't build to provide that much.

Now with Fosi V3 Mono, we came to know all about PFFB.
It seems 3e Audio is the first to implement it after the patent expired some 3 years ago.
TPA 3255 has been around for 6 years, and it's only now we realise about its PFFB capability.
3e Audio is also based in Shenzhen city.
They are experimenting a lot. They also came up with a ready amplifier, with unique thick heat sink bottom plate.

Finished Amp | 3e Audio

www.3e-audio.com