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

Guddu

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*** Note: No measurements are included in this thread ***

While I hope a Review with measurements comes through soon, I am putting together my observations here hoping to provide some clues to someone looking for ZA3 and quick comparison with Aiyima A07 Max.

Few other threads related to these two products:
Fosi ZA3: https://www.audiosciencereview.com/...3255-amplifier-with-mono-stereo-output.48226/
Aiyima A07 Max: https://www.audiosciencereview.com/...first-dual-mode-balanced-amplifier-za3.48552/

Fosi ZA3 amplifier joined my bench today, and currently placed alongside Aiyima A07 Max and Topping PA7

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

1700023713336.png


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* 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

1700023802238.png

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

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Fosi ZA3 vs Aiyima A07

IMG_E1427.JPG


IMG_E1429.JPG


IMG_E1430.JPG


IMG_E1431.JPG


Fosi ZA3Aiyima A07 Max
SummaryStereo 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 & appearanceBigger 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 PSUSimilar or close enough with same spec PSU
Front PanelPower 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 PanelRCA 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 VentsOn both sides
no vents on top plate
On both sides
no vents on top plate
Any issues observed, or things to be aware ofSo 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

Again, I am hoping that a proper measurement based review comes through soon and these details might be used for quick product overlook and comparison.
Would also appreciate if you add anymore information based on your observation on this product.
 
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MCH

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Hi @guddu , question for you: have you tested the trigger input of the fosi? Does it make "pops" when triggered on/off? Thanks!
 
Last edited:
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Guddu

Guddu

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Hi @guddu , question for you: have you tested the trigger input of the fpsi? Does it make "pops" when triggered on/off? Thanks!

I forgot about adding information on 12v trigger and popping noise, just updated in the table.
But Yes, pop out is there when powering ON/OFF and with 12v trigger as well. It's faint, but it's there.
 

Jeromeof

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Here are some other comparison photos as I have a similar set of Amps.
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I have 2 x ZA3 and tried them in the monoblock configuration fed by some balanced cables - very clean sounding
IMG_9054 Large.jpeg
.
I will add some more detail in a few days - as I am still playing around with the best setup including setup with a Wiim Pro doing the 12v trigger output.
 

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Mordor

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Can you provide a subjectif analyses about the sound of the "old" V3 and the new Fosi ZA3?

From what i read, seems that there aren`t many differences.

Thank you.
 
OP
Guddu

Guddu

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Can you provide a subjectif analyses about the sound of the "old" V3 and the new Fosi ZA3?

From what i read, seems that there aren`t many differences.

Thank you.
I don’t have Fosi v3, so can’t really provide anything on that, probably someone else might jump in.
About ZA3, I felt it kind of forward sounding in my setup if you want to take away anything subjective. I have some notes in the post as well.
 

Jeromeof

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Can you provide a subjectif analyses about the sound of the "old" V3 and the new Fosi ZA3?

From what i read, seems that there aren`t many differences.

Thank you.
They sound very similar - though obviously if you add a subwoofer to the ZA3 setup it will have a much fuller bass response and if you have 2 x ZA3 setup as monoblocks you have potentially much more power (I am saying potentially as the V3 has lots of power anyways).

I will capture a frequency response comparison (without any subwoofer connected) in a few days and post it here. The main difference is really if you want to:
1. Use Balanced inputs as well as RCA
2. Have a 12V trigger
3. Subwoofer output
4. Mono block setup
 

NoMoFoNo

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Did posters receive the ZA3 via supporting the kickstarter campaign for the device? If so, is there latest information about wider release date for this model?
 
OP
Guddu

Guddu

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Did posters receive the ZA3 via supporting the kickstarter campaign for the device? If so, is there latest information about wider release date for this model?
I think it would be available in mid December.
@Fosi Audio can confirm official release date.
 

Joe Smith

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Looks good! I especially like that the knob is press on/off so can retain the volume level without readjusting both sides each time if using as a mono amp.
 

surroundman

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Please, if possible, test and see if the SUB-OUT is working well. I'm looking forward to replacing my V3 with the ZA3 for this purpose alone.
 
OP
Guddu

Guddu

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How many opamp? Can be changed?
I think it has 5 op-amps in total and I believe all are replaceable, however
- 1 of them is for balanced input conversion and don’t know if there is any point in changing this one
- 2 op-amps are sub-opamps, used for sub out
- Remaining 2 op-amps are more like v3 op-amps, for stereo channels, could be replaced
 
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Guddu

Guddu

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Please, if possible, test and see if the SUB-OUT is working well. I'm looking forward to replacing my V3 with the ZA3 for this purpose alone.
Sub-out works well, no issues at all in my case.
- The volume knob controls the sub pre-out as well
- if amp is powered Off then no sub pre-out
 
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Jeromeof

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So I had a bit of REW fun today ( new Beta2 released !!) - just so people can 'compare' a V3 and a ZA3 as far as Frequency Response, here are 4 different measurements:
1. ZA3 Balanced input with Subwoofer (just a cheap Monoprice Sub this time- I will use a Kef next week)
2. ZA3 Balanced input No Sub
3. ZA3 RCA input
4. V3 RCA input

ZA3-FR.png


As you can see other than the Subwoofer doing its job the other 3 measurements are mostly identical - so as you can imaging the V3 and the ZA3 sound identical. But the ZA3 Volume pot is more linear than the V3 in that to align these measurements the ZA3 was only at 9pm while the V3 was at around 12pm.

IMO with the subwoofer output and a little bit of EQ applied and the option to run 2 ZA3 as Monoblocks - I would say this setup 'oozes' potential.
 

Joe Smith

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I do think the stereo/mono switch on the front is a very poor design decision. The Aiyima placement of the same function on the MAX seems far safer to me for a daily use item, you're going to be using it one way or the other, not changing back and forth regularly.
 
OP
Guddu

Guddu

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So I had a bit of REW fun today ( new Beta2 released !!) - just so people can 'compare' a V3 and a ZA3 as far as Frequency Response, here are 4 different measurements:
1. ZA3 Balanced input with Subwoofer (just a cheap Monoprice Sub this time- I will use a Kef next week)
2. ZA3 Balanced input No Sub
3. ZA3 RCA input
4. V3 RCA input

As you can see other than the Subwoofer doing its job the other 3 measurements are mostly identical - so as you can imaging the V3 and the ZA3 sound identical. But the ZA3 Volume pot is more linear than the V3 in that to align these measurements the ZA3 was only at 9pm while the V3 was at around 12pm.

IMO with the subwoofer output and a little bit of EQ applied and the option to run 2 ZA3 as Monoblocks - I would say this setup 'oozes' potential.
Is it just me or your graphs really have elevated low and mid-low? It’s pretty uneven?
 

Jeromeof

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Is it just me or your graphs really have elevated low and mid-low? It’s pretty uneven?
Yes it’s not really eq- I normally have a minidsp involved but I removed it from this measurement comparisons as I wanted to measure the balanced and rca - the minidsp I have doesn’t not have balanced outputs
 
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Guddu

Guddu

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Yes it’s not really eq- I normally have a minidsp involved but I removed it from this measurement comparisons as I wanted to measure the balanced and rca - the minidsp I have doesn’t not have balanced outputs
Balanced out shouldn’t be different than unbalanced wrt frequency response.
 
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