Fosi Audio ZA3 Amplifier Review

[gcogger]

Hi there, are you suggesting that you would like the device to offer a high-pass filter with selectable frequency ranges? Could you please recommend which frequency ranges you would prefer to have as options, such as 120Hz-20kHz, 200Hz-20kHz?

I think everyone else has already answered this for me, but:

• What people are asking for is a high pass filter for the main output, in order to integrate the main/sub properly.
• I'd say it needs to be in the 50-150Hz range. Ideally, it would be variable, but if not then 80Hz seems popular.
• Even better would be if the main and sub out were matched in where they roll off. E.g. if there is an 80Hz high pass filter for the mains, there would be an 80Hz low pass filter for the sub.

There are circuits available on the internet that show the idea, e.g. look at https://en.wikipedia.org/wiki/Linkwitz–Riley_filter

 

[Toni Mas]

• Even better would be if the main and sub out were matched in where they roll off. E.g. if there is an 80Hz high pass filter for the mains, there would be an 80Hz low pass filter for the sub.

I don't agree, because in order to get a flatter in room response, some fine tuned mismatch between high pass and low pass is much better. Also high pass and low pass would sum flat only if subwoofer and main speakers are time aligned, or phase is also adjustable. But all this is extremely theoretical because only valid outdoors. In any room the flatest low frequency response is only obtainable empirically, or using room eq. See Geddes multi subwoofer approach for more details.

 

[rj2wells]

I don't agree, because in order to get a flatter in room response, some fine tuned mismatch between high pass and low pass is much better. Also high pass and low pass would sum flat only if subwoofer and main speakers are time aligned, or phase is also adjustable. But all this is extremely theoretical because only valid outdoors. In any room the flatest low frequency response is only obtainable empirically, or using room eq. See Geddes multi subwoofer approach for more details.

I agree. I think it's best to leave the low pass filter to the sub and have the pre out / line out carry all frequencies.

This also makes the device more flexible. For example you could chain a second amp off it to power another room with the full range available.

Almost every active sub already has the low pass filter so it doesn't need to be on the amp. On the other hand passive mains generally never have a high pass filter of their own so that's needed on the amp.

 

[Toni Mas]

Regarding the low pass, imho it is only useful if adjustable or can be by passed. For this reason I prefer the line out of V3 to the sub out of ZA3.

 

[Fosi Audio]

@gcogger @staticV3 @memphiskat

Thank you all for your suggestions! Let me summarize, can we design it as follows?
For the main speaker output, set an adjustable HPF switch with 5 steps: HPF OFF/60/80/100/120Hz.
For the sub out, set an adjustable LPF switch with 5 steps: LPF OFF/60/80/100/120Hz.

 

[rj2wells]

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@gcogger @staticV3 @memphiskat

Thank you all for your suggestions! Let me summarize, can we design it as follows?
For the main speaker output, set an adjustable HPF switch with 5 steps: HPF OFF/60/80/100/120Hz.
For the sub out, set an adjustable LPF switch with 5 steps: LPF OFF/60/80/100/120Hz.

That sounds fantastic. If you had to cut something to save cost, cut the LPF since the sub will almost certainly also have one.

 

[howard416]

There a crapload

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That sounds fantastic. If you had to cut something to save cost, cut the LPF since the sub will almost certainly also have one.

And if you can keep the main balanced in, that would be perfect... But, the crossover filters would have to be at least 12 dB/octave electrical, preferably 24 dB/octave (but the component count and cost go up with all those crossover frequency selections).

Any potential ground loop that might exist due to the single-ended sub-out could likely be solved by running a separate ground strap between the sub's amp and Fosi amp. If the shell(s) of the amp's RCA inputs are electrically tied to the shell of the sub-out, then a simple grounding cable could be made by soldering a hefty wire to the shell of an RCA plug. Plugging that into an RCA input could then bond the amp's signal ground to whatever else needed it.

 

[Sam Kafka]

It's nice to see these these small Chi Fi amps being reviewed and talked about on ASR. I've got four of them and use them for listening to music.

They sound fantastic!

 

[Toni Mas]

@gcogger @staticV3 @memphiskat

Thank you all for your suggestions! Let me summarize, can we design it as follows?
For the main speaker output, set an adjustable HPF switch with 5 steps: HPF OFF/60/80/100/120Hz.
For the sub out, set an adjustable LPF switch with 5 steps: LPF OFF/60/80/100/120Hz.

Will the HPF and LPF be independant?
I mean can I choose LPF=120 and HPF=80 ?

Or HPF=LPF?

 

[oldloder]

Will the HPF and LPF be independant?
I mean can I choose LPF=120 and HPF=80 ?

Or HPF=LPF?

This independence choice would be very helpful especially with the flexibility to choose 12db/octave or 24db/octave slopes since the whole idea is quality sub/mains integration.

There are few options in these small chip amps for this capability. Fosi, doing this would set your product apart from the field and would give folks the capability to eliminate standard receivers and avrs. I think there are plenty of people who don't have the space for, budget, interest or want/can manage the complexity (I can't overstate this part especially) of a large receiver with 8 or 9 speakers. The simplicity and ability to put a 2.1 in one small package with full integration capability would be next level.

 

[ViperDom]

ZA3 ---vs--- Yamaha A-S301

Price: ------------ $150 ------ $350
Size: ------------- Small ------ Traditional
Design: ---------- Class D ---- Class A/B
8 ohm Power: --- ??RMS/100wMax --- 60wRMS/100wMax

Any other differences to consider when choosing between these two budget amplifiers? more specifically Audible?

 

[somebodyelse]

Sensitivity to load impedance, ability to drive 2R load, digital input, phono input, number of analog inputs, balanced in vs. single ended only, tone and loudness controls, A/B speaker switching, remote, trigger input.

 

[Petevid]

They are two very different animals and only interchangeable/comparable if you only compare using the same source. That source could be a Wiim Pro/Plus but the analogue o/p of the Wiim would need to be used even though the Yamaha does has a digital inputs to it’s built in DAC, for a like for like comparison. On this like for like basis l think it very likely they would sound the same being used within their normal operating parameters.

 

[gcogger]

@gcogger @staticV3 @memphiskat

Thank you all for your suggestions! Let me summarize, can we design it as follows?
For the main speaker output, set an adjustable HPF switch with 5 steps: HPF OFF/60/80/100/120Hz.
For the sub out, set an adjustable LPF switch with 5 steps: LPF OFF/60/80/100/120Hz.

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That sounds fantastic. If you had to cut something to save cost, cut the LPF since the sub will almost certainly also have one.

I completely agree

 

[Guddu]

@gcogger @staticV3 @memphiskat

Thank you all for your suggestions! Let me summarize, can we design it as follows?
For the main speaker output, set an adjustable HPF switch with 5 steps: HPF OFF/60/80/100/120Hz.
For the sub out, set an adjustable LPF switch with 5 steps: LPF OFF/60/80/100/120Hz.

This is the way to go, probably most flexible than any other amp without software based controls.
These controls cover decent bookshelf as well as smaller remote/surround/on-wall speakers.

PE. Provided these don’t include additional noise or failure scenarios, not that I anticipate any because I have personally found Fosi’s quality control better than other similar competitors.

 

[memphiskat]

@gcogger @staticV3 @memphiskat

Thank you all for your suggestions! Let me summarize, can we design it as follows?
For the main speaker output, set an adjustable HPF switch with 5 steps: HPF OFF/60/80/100/120Hz.
For the sub out, set an adjustable LPF switch with 5 steps: LPF OFF/60/80/100/120Hz.

This would be fantastic! Perfect for setting up a simple 2.1 setup.

 

[Jimster480]

Nice to see some decent cheaper speaker Amps. Makes me want to possibly get a set of speakers hahaha

 

[Fosi Audio]

Nice to see some decent cheaper speaker Amps. Makes me want to possibly get a set of speakers hahaha

Go get it.

 

[Guddu]

Nice to see some decent cheaper speaker Amps. Makes me want to possibly get a set of speakers hahaha

I saw some Fosi speakers on Fosi’s facebook page, you got a candidate there

 

[Bruce Morgen]

I would prefer a device that has a high pass filter, as described above, and no low pass filter. Active subs already have the LPF it's the HPF that I'm missing.

Right now I'm searching reviews of active HPF and not finding anything better than the $260 miniDSP to put between my wiim pro and my fosi v3 (sub would then be upstream of the fosi).

It's probably not "better than the $260 miniDSP," but the Dayton Audio DSP-408 is a good deal cheaper and might -- or might not -- do the job to your satisfaction. I use one to EQ all four of my ambience/surround speakers to excellent effect, FWIW -- I nabbed it on sale at Parts Express for $120 a couple of years ago IIRC.