Fosi Audio ZA3 Amplifier Review

[doug s.]

I LIKE the volume control. In future it might be a good idea to provide a volume "bypass" switch to fully satisfy some users.

Max volume is bypassing the the control as well as adding a switch.

doug s.

 

[doug s.]

I'd be far more concerned about the load-dependent frequency response

Why? It's pretty unlikely that it's audible for the overwhelming majority of people with the overwhelming majority of speakers. It's feasible that it might be an issue in some cases, but it's easy enough to determine.

doug s.

 

[doug s.]

The Sony TAN77es fixed input sensitivity is 1V for full rated power (I have three here) and the attenuators offer full control on the variable input.

Most power amplifiers sold in the past had level controls. Not all, but most, up until the poverty pack specials of the last decade.

One of mine:View attachment 351635

Actually, most higher end power amps didn't, and still don't have volume controls. I bought my first "separates" power amp in 1984, and my aiyima a07 max's are the 1st amps I ever bought with volume pots. Actually, I take it back; last year, I bought a used pair of crown xls2000's; they also have volume pots. Adcom, electrocompaniet, alchemist, audio mirror, hafler, mesa; nary a volume pot anywhere. Maybe more consumer focused amps?

doug s.

 

[doug s.]

Ah, man, if it had PFFB I would buy one just for shits and giggles. As it is, I may buy one anyway since I know someone who could definitely use this, and probably wouldn't notice any issues in the treble. The balanced input together with volume-controlled sub out are freaking killer features at this price point.

You won't notice any issues in the treble either.

doug s.

 

[doug s.]

You can "spin to win" a coupon code for up to 20% off on the fosiaudio dot com. Try all of your email addresses, try all of your browsers, ...

48V version, $150 - 20% = $120

You'll get 15% every time.

doug s.

 

[Sir Sanders Zingmore]

Why? It's pretty unlikely that it's audible for the overwhelming majority of people with the overwhelming majority of speakers. It's feasible that it might be an issue in some cases, but it's easy enough to determine.

doug s.

I guess I was attempting to focus on the thing that’s more likely to matter.
I was answering a question that seemed to be focusing on the audibility of SINAD.
Whilst the SINAD of this amp is not state of the art, it’s much less likely to be audible than the non-flat FR.

 

[Deleted member 48726]

Why? It's pretty unlikely that it's audible for the overwhelming majority of people with the overwhelming majority of speakers.

doug s.

Most speakers are not linear in phase and impedance at all and so they will interact with the high output impedance of the Wiim amp. Now, as much as I like an amplifier that is true to the signal, others may not care.

I can easily hear a 1 dB difference in the presence and up. I bet you can as well.
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Complex impedance load amp FR influence - WiiM Amp review by Erin

That’s a start, though the THD vs Frequency vs Power is very hard to read. All other graphs are not biased to 0 dB, making them also harder to read. He will improve no doubt :)

www.audiosciencereview.com

Complex impedance load amp FR influence - WiiM Amp review by Erin

It is quite clear these kinds of deviations are generally audible in A-B tests. Cheers. Do you have a link for that?

www.audiosciencereview.com

 

[doug s.]

It's not the price tag ... is the result / SQ .. and some of those "inexpensive amps" sounds as good as other amps with 3 zeroes in the price tag.
That's ASR mission, to show the truth.

And in one case I know of, four zeros. Not so many zeros, in my case, because I've always been cheap, heh! But I bought two aiyima a07 max's specifically for my main "critical listening" system; a horn based active 4-way setup. I was considering the fosi v3's but preferred the speaker connection of the aiyimas.

doug s.

 

[doug s.]

I guess I was attempting to focus on the thing that’s more likely to matter.
I was answering a question that seemed to be focusing on the audibility of SINAD.
Whilst the SINAD of this amp is not state of the art, it’s much less likely to be audible than the non-flat FR.

I understand your point, but my point is the frequency issue is still extremely unlikely to be audible, and I think it just upsets a lot of people because of how it looks on a graph. When in reality, it's the possibility of about 0.5db-2.0db rise above 20khz, and who's going to hear it, even with speakers it may affect?

doug s.

 

[doug s.]

Do said audiophiles use 2.1 without a DSP/measured room correction eq (which will also set low and high pass filters of course?). Getting a sub dialed in without dsp is a nightmare in terms of critical listening. They would be better off just using big towers for 2 channels in most cases if they need deeper base

I've never had a problem dialing in my subs, in a variety of rooms, with a variety of different speakers. No dsp needed, although I did use it once, with a deqx pdc-2.6. I still have it, but it's a pita to use, so it sits. I've had great results just using a pink noise generator and spectrum analyzer to adjust my outboard active crossover.

doug s

 

[doug s.]

Thanks, so theoretically it´s better to set the ZA3 lower if you don´t need the full power?

I'd say "it depends". Like the amp, some dacs' performance varies with the level attenuation, and some may perform better with their volume pots maxed out.

doug s.

 

[doug s.]

Most speakers are not linear in phase and impedance at all and so they will interact with the high output impedance of the Wiim amp. Now, as much as I like an amplifier that is true to the signal, others may not care.

I can easily hear a 1 dB difference in the presence and up. I bet you can as well.
-->

Complex impedance load amp FR influence - WiiM Amp review by Erin

That’s a start, though the THD vs Frequency vs Power is very hard to read. All other graphs are not biased to 0 dB, making them also harder to read. He will improve no doubt :)

www.audiosciencereview.com

Complex impedance load amp FR influence - WiiM Amp review by Erin

It is quite clear these kinds of deviations are generally audible in A-B tests. Cheers. Do you have a link for that?

www.audiosciencereview.com

I sure can hear a 1db difference in level in the presence region. But this anomaly doesn't even begin to come into play at all until the high treble range. You will never hear the difference.

doug s.

 

[doug s.]

That is how my current system is set up. I have a Benchmark DAC2 with XLR out to a Buckeye Hypex 252 amp and then onto the mains. The RCA out goes to a 12" sub with the cross over set at 65Hz. This works really well and sounds great, however, the mains are playing at full range, as is the Buckeye amp driving them.

With a cross over imbedded in the DAC, or the sub out in the amp, you can alleviate the stress the lower frequencies place on both the amp and the main speakers. If you have a powerful amp and tower speakers it not so important, however, for a 2.1 system incorporating bookshelf mains and a sub it is extremely useful, especially if your measuring with REW software.

Unless the woofers in your main speakers are crossed over to their midrange drivers ~200hz or less, it's still useful to high pass them with an active x-over, imo.

doug s.

 

[doug s.]

balanced is nice if your source is balanced... otherwise you have to get a strange cable... like XLR balanced out to RCA input.... why not get the balanced version of the amp if your source has balance output... XLR balanced to XLR balanced input.... see how that works

In this case, if you have a balanced source, the only "benefit" is you don't have to use an adapter on your xlr/xlr cable - the adapter is built in to the amp. But the amp isn't a balanced amp. Its internal circuitry would have to be doubled to be truly balanced.

doug s.

 

[doug s.]

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?

Simplest solution would be to have the speaker outputs automatically high passed at 80hz if a cable gets plugged into the subwoofer output. 99% of your users will connect to a powered sub so won't need a low pass there. You could make the hi-pass adjustable, a bit less simple, from 0hz to, say, 150hz, which should handle pretty much anything, from no hi-pass crossover to 150hz; either continuous, or 4-6 different set frequencies. I'd also recommend 24db/octave slope.

doug s.

 

[Deleted member 48726]

I sure can hear a 1db difference in level in the presence region. But this anomaly doesn't even begin to come into play at all until the high treble range. You will never hear the difference.

doug s.

The example by Erin's complex load is a mild one with a 20 ohm peak. It can easily get to 60 ohm for some speakers and high ° of phase. This exaggerates the issue even more. For 3 or 4 way crossovers it could also be present at even lower frequencies. You can see from the trace that even the mild 20 ohm peak has ripple effects much below its actual peak frequency.

Also; if you'd be so kind to combine your responses into less posts if you respond to many different ones at the same time. You can make several quotes into one post. This make the thread look a bit cleaner.

 

[doug s.]

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

Or HPF=LPF?

This is a good question. If they are not independent, it would be better to just delete the low pass crossover altogether. Let the powered sub handle it. There are times having independent high and low pass crossover points are better.

doug s.

 

[doug s.]

The example by Erin's complex load is a mild one with a 20 ohm peak. It can easily get to 60 ohm for some speakers and high ° of phase. This exaggerates the issue even more. For 3 or 4 way crossovers it could also be present at even lower frequencies. You can see from the trace that even the mild 20 ohm peak has ripple effects much below its actual peak frequency.

Also; if you'd be so kind to combine your responses into less posts if you respond to many different ones at the same time. You can make several quotes into one post. This make the thread look a bit cleaner.

I'm sure, as I said, that there may be some cases where a particular speaker may be more susceptible to this. And there are undoubtedly people who are more sensitive to this.

In my case, I looked at the impedance load of the driver from 175hz-7khz that the amp would be driving. I was not concerned about the amp that would drive >7khz because I don't think I'd notice it, and besides, I knew I'd be able to adjust the crossover pot when using my pink noise generator and spectrum analyzer to adjust the volume of the four separate drivers in each channel.

And then, there's the reality that what happens on the recording end has so much influence on what you're hearing on the playback end, that these still relatively small differences may help in some cases, hurt in others, and not matter at all sometimes.

Re posting answers to different questions in the same post, I actually find it's a bit disjointed. And I think what you're seeing is a flurry of posts from me, because I started reading this thread from its inception, and had comments to the earliest posts.

doug s.

 

[Witterings]

This amp, (and the aiyima a07 max's I use), sound as good or better than AMPS costing several thousand dollars or more

That's brilliant and just what I'm looking for as The Mrs doesn't like the size my current system takes up so any oppotunity to get something smaller is only going to win me some brownie points .... I'm assuming you currently own a ZA3 and have back to backed them against what you currently have?

You also use the plural of saying AMPS rather than just one .... how many AMPS do you currently own costing several thousand dollars that sound better than this .... can you list them please including how you tested them, as much as anything might help anyone avoid buying them in the future.

Some pictures of the ZA3 next to your other AMPS would be brilliant as well, I'd help us all put some scale into the scenario, I think there'd be a huge audience for an amp that size and cost that sounds as good or better than amps costing so much more and keeps the significant other happy ... especially at the cost, less than a pair of Jimmy Choos ... that'll stop her nagging I spend too much on HiFi

 

[AudioKC]

Why not a07 max? You can buy 2 for only a few dollars more than the za3.

doug s.

I think because better performance in SINAD and ZA3 has sub crossover out of the box.