Fosi Audio's First Dual-Mode Balanced Amplifier ZA3

[damascato79]

Quick questions: how do I sent 2x of these amps so I can control the volume through an external preamp? Cheers!

 

[K.Kevin]

Just went live on Amazon, but the 20% early bird coupon doesn't work yet

Edit: 20% Coupon working on ebay, stacks with the 10% offered on the page

I cant see how it stacks

 

[Palladium]

Is Amir gonna review this?

 

[abbazaba]

Its not working for me. It does the 10% off $149.99 = $134.99 and the discount code takes off $13.50 for a total of $121.49.

What final price did you see?

Late night math mistake for me, sorry! Looks like it gave 10% + 10%, for $28.50 off, just short of the full 20% ($30 off), same as you. Fosi sent me a new Amazon code this morning, which gives the full $30 off, but it doesn't stack on Amazon either.

 

[nastynick]

Thanks!

 

[Extreme_Boky]

Can someone (@Fosi Audio maybe..??) confirm please..?? See below...

 

[daniboun]

Another TPA3255 amp without PFFB

My guess for the next PFFB Fosi amps :

 

[daniboun]

Seen @ Fosi Audio site:
* V3 specs: Power 300Wx2 @4Ω, SINAD 88dB, THD 0.003%, SNR ≥110dB
* ZA3 specs: Power 155Wx2 @4Ω, SINAD 89dB, THD 0.006%, SNR ≥106dB

Something feels wrong at those specs:
* Regarding Power: one or both of the stated values seem wrong
* Regarding SINAD vs THD: SINAD increases AND THD increases too? If I am not wrong, when THD increases SINAD decreases (and vice versa), as they are representations of the same physical and measurable property.

Based on the values published at the Fosi site, Fosi ZA3 amplifier will be a worse amplifier than the Fosi V3. All this happens as some TPA3255 boards start to measure really well here at ASR (for instance: 3e audio TPA3255 260-2-29A).

A sugestion at @ Fosi Audio:
a) take a serious look at 3e audio TPA3255 260-2-29A, that seems to be the golden standard right now; can you sell us a box that does just that?
b) sell us a FOSI V4 with proper PFFB TPA3255 board + a good internal 39V/10A power supply + a metal case / dissipator (like you have done with the ZA3). Forget about sub-out and multiple front switches. Leave a back switch to switch between 2ch and 1ch output (this is the other reason to have a proper builtin 10A power supply).

I will be among the first to buy such an amplifier (just for the fun of it)

The "current limited" vs "voltage limited" debate has already been discussed for TPA325X amps.
The choice of PSU will depend on several factors, including the speaker impedance and also the choice of module (PBTL Mono / BTL Stereo)

I shared a table here on page 2 : Bamboo project

Under 4R the current considerably influences the power
Under 8R we are more dependent on the voltage

Here another good example :

 

[PlasticDoc]

The "current limited" vs "voltage limited" debate has already been discussed for TPA325X amps.
The choice of PSU will depend on several factors, including the speaker impedance and also the choice of module (PBTL Mono / BTL Stereo)

Read again my post as it has nothing to do with the current vs voltage debate.
The specs found in Fosi site and in the V3 and ZA3 user manuals, refer to both amplifiers using the same 48V5A PSU.
When in doubt just read the manual...

 

[daniboun]

Read again my post as it has nothing to do with the current vs voltage debate.
The specs found in Fosi site and in the V3 and ZA3 user manuals, refer to both amplifiers using the same 48V5A PSU.
When in doubt just read the manual...

From user manual I see this (the testing conditions are not announced and are not clear I agree )
If ASR measurements exist, it is also so as not to rely on sometimes hazardous documentation.


For the ZA3

For the V3 ( we only see the PSU range....)

 

[MCH]

Another TPA3255 amp without PFFB

My guess for the next PFFB Fosi amps :

View attachment 335949

Do you realise that even your DIY pffb amp was more than twice the price of this amp?

Not everyone cares about load dependency of a few dB Sinad, specially in this price range.

 

[K.Kevin]

Another TPA3255 amp without PFFB

My guess for the next PFFB Fosi amps :

View attachment 335949

I never understood whether there was significant benefit of PFFB.

I thought what it does is eliminate the high frequency rise (or drop) around 20khz due to the load dependency. I also heard it improved sinad and distortion a couple percentage points.

Putting the sinad aside, Can you explain why or how PFFB will make an audible difference to those who are hearing limited and cannot hear 20khz? For example, I cannot hear past 15khz, just due to natural age loss over time. Would there be any benefit to PFFB?

 

[TonyJZX]

whether its important or not is up to you

however its clear Fosi care and I'm guessing the rest will follow

they already said there next unit will feature this and didnt they buy an example amp from that Phillipino outfit?

The Chinese copying <Ahem> researching the competition.... so what else is new.

 

[K.Kevin]

whether its important or not is up to you

however its clear Fosi care and I'm guessing the rest will follow

they already said there next unit will feature this and didnt they buy an example amp from that Phillipino outfit?

The Chinese copying <Ahem> researching the competition.... so what else is new.

That doesn’t really help though

Can you articulate what the benefits of PFFB are?

 

[Power Pop 23]

That doesn’t really help though

Can you articulate what the benefits of PFFB are?

As I understand it, a careful implementation of PFFB can result in an amplifier with lower measured SINAD than the same without PFFB.

 

[quocheiser]

Thank you for your advice. Our R&D team have been focused on implementing PFFB for the past few months and has recently made significant breakthroughs. Stay tuned, as we might introduce a new amplifier supporting PFFB as early as next quarter.

@Fosi Audio Audio thanks for your exciting update regarding PFFB.

It would be great if your next amplifier using the TPA3255 would also use a 52V power supply, similar to the Topping PA7 Plus.

Then the output wattages from Fosi would be extremely competitive, especially against the Hypex based D-class amps that many on this forum compare your products to.

Fosi Audio would then have a real giant killer in my opinion, and an unbeatable value proposition in the current market.

 

[ComasSky]

It would be incredible to be able to bypass the preamp with a switch to transform the za3 into a stereo or mono power amp.

 

[daniboun]

Do you realise that even your DIY pffb amp was more than twice the price of this amp?

If you are desperate to buy an amplifier at a lower price then indeed it will be at the sacrifice, at one point or another, of performance)
I would have a hard time comparing a 3E Audio module or even a Sylph Audio to this Fosi with all due respect.

 

[TonyJZX]

i find the argument about this specious at best... i have no opinion of pffb

however if you dont like it, buy a v3 za3 or any number of units out there.... the world is your oyster

you want pffb? well then fosi are coming to the rescue

why are people against inovation? (ie. Tim Apple)

 

[daniboun]

I never understood whether there was significant benefit of PFFB.

As reminder....


3E Audio 260-2-29A (PFFB)

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PA5 II (PFFB)

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Fosi V3 (no PFFB)

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This is a review and detailed measurements of the Fosi Audio V3 stereo amplifier. It was sent to me by the company and costs US $89.99 with stock 32 volt supply. Price goes up to $109.99 with the 48 volt supply. There is a $10 discount coupon right now. Despite its budget price, the V3...

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Aiyima-a07 (no PFFB)

AIYIMA A07 TPA3255 Review (Amplifier)

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