late to the party as usual. I've got the FY FZY FY FZY bear uh za3 little desktop-type amplifier. Now, I paid for this myself. I ordered it from Amazon, and the idea is that I'll just give it to somebody when I'm done with it. Uh, about 150 bucks for this guy with the 48-volt power supply. Now, keep in mind the power supply is about half the size of the amplifier itself. Now, you may not care about that. Personally, I don't either. It would be neat if it was somehow incorporated into this, but in doing so, they keep the noise level down, and I'm okay with that. You know, you just tuck it off to the side, put it on the floor, or maybe use it as a door stop. Do whatever you want with it. Now, you'll notice we've got a couple switches on the front and a volume knob or a gain knob or an input sensitivity adjustment, whatever you want to call this thing. Basically, we all know this as a volume knob. Now, my car audio

Friends are going to say again, it's not a volume knob. Okay, kind of is. The XLR, I should put it better. The back, the XLR on the back input, and then RCA inputs as well, can be switched on the front like that. And then let's see here. Oh, we also have mono and stereo mode. So this is two-channel output, but it can be used as mono, so you just switch right there. The thing about the mono mode with this amplifier is that it does not double the output power of the two channels, right? So it's not bridged mono, it's just mono, and it gives a little bit more power to the single output, which is this guy right here. Another thing that I want to point out is it has a subwoofer output. Now, that's pretty cool, except I'm going to show you why it's not pretty cool in the measurement section of this video. You can get another version of this amplifier with a lower voltage power supply. So power-wise, you get more output power.

with the 48-volt power supply that comes with the version that I bought. Now, if we look at the ratings together on here, we can see that there are two separate sets of ratings, and then two separate sets of ratings between that, and then two separate sets of ratings between mono and stereo. So, we're going to focus on this section right here, the 48-volt 5 amp, which is what I have. They say stereo mode per channel at 1% THD at 4 ohms is 180 watts, 8 ohms is 95 watts. Mono mode 4 ohms 235, 8 ohms 120. That should be adequate to drive pretty much any speaker within a reasonable sized room or listening distance. And in my case, I'm listening in an 18x14x9 ceiling room at about 10 ft away. Now, I've listened to a few different speakers from PSB Audio's Imagine B5, B50 bookshelf speaker, two PS Audio's F FR10 tower speaker, as well as

the Mofi Source Point 10, as well as the Elac Vila BS 43, because these are all speakers that I have on hand. I didn't have any issues driving these speakers to adequate output levels, at again 10 ft away, and what I would consider maybe a medium-sized room. The interesting thing though is that in the measurements, there seems to be a head scratcher. I'm going to save that for a little bit, and we'll talk about that in a little bit with those speakers in that room at that distance. It was okay, it did what it needed to do. At this point, there are already so many other reviewers that have talked about this amplifier, and they've given you subjective opinions that I don't really want to waste my time. Number one, because they've already done it, but number two, which really overrides number one, is when it comes to subjective performance or subjective analysis. Like, you know, I think I heard a lush bottom in this amplifier, is more transparent than this one. A lot of

the times these guys aren't doing Blind testing, they're not doing backtack ab, or ABX testing even, and they're not even level matching between amplifier outputs, so I really take subjective opinions about how electronic sound with less than a grain of salt. Is a grain of sand smaller than a grain of salt? Because if it is, that's what I take it with. Personally, I rely on objective measurements to tell us is the amplifier performing the way it's supposed to. Does it have flat frequency response? Does it meet the Power? Can it drive this speaker at this particular resistance or ohm load? What I'm going to start with is frequency response. How does this amplifier react when a speaker is attached to it or a static load is attached to it? So what I do for my testing is I test with two different static loads, a 4 and an 8 ohm, and then I test with two reactive loads, a simple and a complex. Now these reactive loads are designed to emulate a real speaker. The reason I don't use a real speaker

for this test is because I test at different output levels, and I don't want to potentially blow speaker or blow out my eardrums. If you want to know more about these reactive loads, I will have it on my website aens audoc corner.com. In this review, first of all, the 8 ohm and the 4 ohm static loads. 8 ohm is in red, 4 ohm is in blue. Let's look at those frequency response from 10 htz to about 22 23 khz or so, and I've measured at 48 khz sampling rate. What we have with the 8 ohm is an increase of about maybe 6 to 7 t0 of a decel t of a decb, and at 10 khz, it's about 3/10 of a deel up. Basically, what's happening with an 8 ohm resistance, you're going to be increasing the output at higher frequencies, and with a 4 ohm resistance, you're going to be decreasing the output.

at higher frequencies, but these Trends are they going to be audible, possibly, but most likely not, and this is where I find that complex loads really help us better understand what is going to happen, what most likely is going to happen in terms of audibility, because we can talk all day about I heard X, Y, or Z. Most of the time, I'm going to believe that whoever is saying it is full of crap, unless they can show me some measurements or some proof as to how they heard what they heard, and it should be easy to prove. So, with these different reactive loads, starting with the simple in green, we can see that around 3 kHz, there's about a half a decibel bump, and then it swings pretty quickly to about a/4 D at 5 kHz, and then it swings pretty pretty high again, uh, at around, let's say, centered about 14 kHz, of about maybe 7/10 of a decibel. Now, what about a more complex load, something that has a lower ohm rating and then has a little bit higher

resistance depending on the frequency. That's in Orange. The thing that I want to note about these swings are that they're pretty broad. Now, if you have a very narrow filter, it's going to be harder to hear that. But when it's very broad, it's going to bring more attention to that range of frequencies. So if we look at this big bump, we've got a range from about 3 to around, I think that's about 14 kHz or so, but I'm going to round down to make this math easy. 3 to 12 kHz is two octaves. You go 3 to 6, and then 6 to 12. So you double that range twice. So that's two octaves where you have about 7 point, yeah, about 7 dB of total amplitude modulation. Are you going to hear that? Yeah, I think so. I think out of all the a complex load is most likely to be heard. But this also goes to show us that you could possibly, now I'm not saying you will, but you

could possibly hear a difference with different speakers, and that's what we call load dependency. Now let's move on to the subwoofer. When you plug in an RCA to the subwoofer output, what do you think is going to happen? What do you want to happen? Now, if you're like me, what you would want to happen is you would want for the amplifier or whatever you're using, DAC preamp, whatever, to say, Oh, you've got a subwoofer plugged in. That means I can attenuate the main speakers. I can add a high-pass filter to them. And that way, it takes the load off the main speakers and applies that frequency band to the subwoofer only. But what you get with this Fucy ZA3 amplifier is that it doesn't do that. Instead, as this graphic shows, when the subwoofer is engaged, this is the response of the subwoofer. Now, this is not variable. You can't change the frequency of the crossover. This is fixed. It goes down about -3 dB. Is it about, let's say

180 Hz or so. As you can see in the Red Line, this is the response of the speaker outputs when the subwoofer is engaged. And notice, this is flat all the way down to 10 Hertz. Now, what does that mean? That means when you plug a subwoofer in, the main speaker outputs are not attenuated. They do not have a high-pass filter applied to them, which then means that your main speakers are still playing down to 20 Hz, down to 10 Hz, and your subwoofer is also playing that, which honestly, to me, seems really silly. It entirely defeats the purpose of having a subwoofer preout, at least in my opinion. If you're curious what the subwoofer pre-out voltage is, I'd say I'm about half a volt RMS output. So now let's talk about power. And I ran into something that was kind of interesting through my testing. When I test, I test with a certain stimulus length, 64k FFT size. I do the same thing as I did for frequency.

response I do 8 ohm 4 ohm a simple reactive load, and a complex reactive load, and that's what I'm showing you here in this graphic. 8 ohm is in red. We can see that we hit about maybe 10 watts or so before the distortion starts to ramp up pretty pretty quickly. Now this is both channels driven at the same time. I'm only showing the result for the right channel. The 8 ohm rating is 95 watts at 1 kHz THD of 1%. So let's go up to 1%. 8 ohm hey that actually that actually does better oh that's kind of cool all right cool yeah. So what happens with 4 ohm now? 4 ohm is rated at let me look here 180 watts at 1%. Okay now that this says stereo mode per channel. 4 ohm is in this light blue and we can see that it's ramping up ramping up ramping up and then you get to about maybe 105.

Watts or so, and then shoots over this way. Well, what happened? It went to protect so why is it only 105 Watts? Well, I thought that was really weird. I think like it's supposed to be 180 Watts. I've seen somebody else's measurements that show that it definitely goes above 105 Watts at 40 with B channels driven. So what's up with that? Uh, I don't know. Well, then I started doing some investigation, and it took me about 2 days to realize what was going on. But let me show you. If you test with a different stimulus link, and in this case it's about 8K stimulus length or 8K fft, the difference between 8K and 64k is basically AK would be likeo boop boop and it just go Boop Bo Boop, and it's pretty quick. With 64, it kind of hangs on in that stimulus a little bit longer. So it's like all right. So like least like that, right? That's ridiculous anyway. I hope

you get the point. So, with that said, let's look at 4 ohm now with a shorter stimulus length. 4 Ohms, same color in this light blue and look, it ramps up and we get to about maybe 150 or so, or something like that, before it ramps up and hits that knee. And then at 1%, I'd say we're probably maybe like 160 or so. So, it's kind of close to their rating, but it's interesting that now with a shorter stimulus length, I'm hitting close to what the manufacturer says. But with that longer tone, I'm definitely not, and it goes into protect and the amplifier shuts down. So, when you're comparing my results to other people's results, maybe keep that in mind. What happens if I switch this thing over to Mono mode at 8 ohm? I'm hitting about, I don't know, maybe 115 or so Watts, I guess. And then at 4 ohm, it's hitting about 190 or so. Now they say the 4 ohm rated is 235 at 1%.

THD. Yeah, maybe I'd give it to them. I mean, that's kind of close. And at 8 ohm, the rating is 120 watts at 1% THD. In the audio industry, it's very for people to test with just one tone to figure out maximum power and the THD versus frequency and the THD versus Power that you've seen me talk about before. It's almost always with 1 kHz. That's just how it's done. What I like to do is kind of go A Step Beyond that. So what I'll do is I'll test at low power with a 1 kHz tone, and then I'll Implement a multi-tone signal into that and see if I'm achieving the same power. Then I ramp the output up until I get to close to rated power with a single 1 kHz tone, and then I'll do a multi-one with that. See am I getting the same power or am I getting less. Now with the NAD C350, that worked out. I was getting the same power.

which means that the power supply was very robust, and it could deliver the same amount of power across all sorts of frequencies as it could with just one tone. That's what you want. Their rated power is 95 Watts at 1%. Which actually I cheat better than that, but I'm going to go to that point, and we're going to see what happens. But first, what we need to do is do a low sanity check. Pay attention up here. So, this is going to be the input stimulus 100 molts RMS into the amplifier, and this is going to be the power out at 8 ohm. I'm going to hit run for a 1 kHz tone, and I get 1.2 watt output right here at 8 ohm. So now, if I switch over to multi-one with that same input, I want to get the same power that we just got. Oh cool, 1.22 Watts. So basically the same power that we just got. Now, what this tells me is that at lower power, regardless if I'm feeding it

just a single tone or a slew of tones like maybe music would have then it achieves the same power output. Now if I ramp this thing up to a point where it hits about 95 Watts or so, 95 Watts at 2 dBV or 1.25 volt RMS. So I'm going to take 2 dBV and I'm going to type it into multi-one two, and I want to hit, remember, 95 Watt. Let's see, do we do that? Oo, I lost, and now we're down to 77, so I've lost about 18 Watts at 8 ohm. All right, okay, all right, so we did lose power with an 8 ohm load. All right, so now what I'm going to do is I'm going to do all this with a 4 ohm load. Now if we go back to the graphic that I showed you earlier where it just kind of dies around about 105 or so Watts, I'm going to show you exactly what I'm talking about first. Okay, okay, I'm at 60 watts.

with about 7 volts input. Pay attention here 'cause something funky is about to happen. At 75 Watts, 93 Watts. Okay, cool. Oh, what happened? The signal just dropped off. The amplifier went into to protect. And now what I'm going to have to do is reset the amplifier. So hold on. All right. I'm at about 94 Watts with a 1 kHz tone. And I'm going to switch it over to multi-one using the same input voltage. So let me turn this off, turn this to minus. I'm going start with minus three. I'mma walk into it. Minus one is where I need to be to get 95 Watts. All right. Minus 3, I'm at 57 now. Minus 2, what happens? 71. All right. So now I'm going to go to minus one. It needs to be 95. Minus one, 86. So I'm about 9 Watts or so off from the point where the amplifier went into protect, maximum output, which was 95 Watts. Still, it shouldn't have gone into

to protect it should have been able to deliver more power. They rate this at 180 watts per channel in Stereo mode at 4 ohm, and I was able to achieve about half of that, which closely aligns with this value. So to recap what I just showed you: at 8 ohm, both channels driven, the maximum that I went up to was 95 Watts because that's what they rate this at. When I applied multi-one, I lost about 18 Watts. When I tried to do the same thing with a 4 ohm load, I cannot achieve the maximum power that they rate this at. Now the truth of the matter is that these measurements give us insight into the fact that the amplifier doesn't do what it's supposed to do for the 4 ohm static load. But I used four different speakers of varying sensitivity and varying complexity in their overall impedance presented to the amplifier, and I was able to drive them without going into protect and to get loud enough levels where I was satisfied.

in a medium-sized room at 10 ft away. I think my main issue, as far as real world goes, I mean outside of the measurements, right outside of the measurements, and it kind of having issues with Forum load. My main issue is the subwoofer output. I don't know why in the world anybody would have a sub for output and not high pass the mains. There's listen, I've been doing this for a long freaking time. I get people want to do gain overlap or people want to do crossover overlap, I should say, and it gives them the sense of look. You can even argue that we can talk about distributed base modes and things like that, but that's horse hockey. The purpose for having a subwoofer is to alleviate the load of your Mains. So when you plug in a subwoofer, I want to see a highpass filter implemented. So that's my request to fzy, that's my time with the fzy. My overall recommendation is, you know, like biggest issue subwoofer output 150 bucks maybe you want to buy.

it. I don't know if you do still want to buy it after watching this review. I will have an affiliate link in the comment section below, feel free to use that. It helps me out with a small commission, like 4%. So, four times 15 is, I can't math, but maybe six bucks or so is what I would earn off of it. You don't have to buy it personally. If you can swing the wamp, I would go that route, but I realized they're not the same thing. The wamp has streaming and HDMI built into it, all that stuff for double the price. It's definitely worth it, but if you're really looking for just a small desktop amp, this will do the job. Just don't plug a subwoofer into it thinking you're going to high pass the mains. I know I'm harping on that, but it's probably like one of the most annoying features that I've ever seen somebody implement into an amplifier that has sub for output. It just seems silly to me. So, that's my

honest sake. And if you don't like it, let me know in the comment section below. I'm sure you will. I will talk to you all later. Oh, and if you want to join me at patreon.com, please do so. Uh, that helps support me, helps me keep this channel going, helps me afford to buy these kind of things to test. And I will talk to you all later. Take care. Peace.

Fosi ZA3 Amplifier Deep Dive Review (with Data)

Welcome to my little corner of the internet.  This is where you can find objective testing of a wide variety of audio gear with a dash of subjective feedback.  The goal here is to help you be a better educated consumer.  

If you're looking to gain some knowledge and share some laughs, come on along with me and enjoy the ride.  

- Erin
