Fosi Audio ZA3 Amplifier Review

[olds1959special]

I found a subwoofer Y splitter cable that splits the single RCA sub output from the ZA3 and splits into two for plugging into the subwoofer, and now use this with my Fosi ZA3, I wonder if it improves the sound since more signal should be going into it.

 

[NBO]

I was running a pair of these in mono mode with a Zd3 DAC/preamp. Nice inexpensive setup. I like the sub out feature of the Za3 with it's built in low pass filtration, but when trying to make my own inline HPF for my bookshelf speakers (Hsu HB-1 Mk2) between the Zd3 and Za3. I needed the Za3 input impedance. Fosi declares the RCA inputs as 47K ohm. After several emails to Fosi (they always respond within 24 hrs, incredible), they initially told me they could not provide an impedance value for the XLR inputs. I pressed a bit, and the updated response ("from the engineers") is there is no stated value because it's near infinity. So much for an inline HPF via XLRs.
I don't know enough about electronics to know how believable or practical a near-infinity input impedance is. If anyone cares to measure this for the XLRs, perhaps you could report it.
But for my intended use of sending line level signals to my woofer (Hsu VTF1-mk2) and generating a HPF signal to the HB-1 mains, I can only see one option - to run three Za3s, two running in mono mode driven by the Zd3's RCA connection with my inline HPF. Then route (via XLR) a concurrent signal to a 3rd Za3 and use the subwoof output from that third..

I guess that begs the question of just how important it is to me to HPF the mains!

 

[Jimster480]

Wondering if this would be good for a set of Atmos channels? I was thinking to get this to power some Atmos channels that would sit on top of my RP-8000F II's and then I can use the sub output as well.
Does this amp have auto on-off? Right now I use 2x Fosi v3 Monoblocks for the speakers themselves. Don't want to add the Atmos channel on top of the other channels as I think it will reduce power output too much.

 

[NBO]

I don't think Za3's have have auto on-off or standby modes like I see on my subwoofer. I'm using 12v trigger signals from the Fosi Zd3 "preamp" to trigger the dual Za3s on and off, but I don't think they have auto on-off that triggers on signal detection.

 

[SoySalsaPicante]

I was running a pair of these in mono mode with a Zd3 DAC/preamp. Nice inexpensive setup. I like the sub out feature of the Za3 with it's built in low pass filtration, but when trying to make my own inline HPF for my bookshelf speakers (Hsu HB-1 Mk2) between the Zd3 and Za3. I needed the Za3 input impedance. Fosi declares the RCA inputs as 47K ohm. After several emails to Fosi (they always respond within 24 hrs, incredible), they initially told me they could not provide an impedance value for the XLR inputs. I pressed a bit, and the updated response ("from the engineers") is there is no stated value because it's near infinity. So much for an inline HPF via XLRs.
I don't know enough about electronics to know how believable or practical a near-infinity input impedance is. If anyone cares to measure this for the XLRs, perhaps you could report it.
But for my intended use of sending line level signals to my woofer (Hsu VTF1-mk2) and generating a HPF signal to the HB-1 mains, I can only see one option - to run three Za3s, two running in mono mode driven by the Zd3's RCA connection with my inline HPF. Then route (via XLR) a concurrent signal to a 3rd Za3 and use the subwoof output from that third..

I guess that begs the question of just how important it is to me to HPF the mains!

What is your source? If you're listening to streaming audio, there are streamers with bass management and a sub out that would work fine before you get a signal out to the ZD3 & ZA3s.

Another option is a Fosi ZP3 preamp, which has adjustable high-pass filter. You can place one of these between the ZD3 and the ZA3s.

 

[Jimster480]

I don't think Za3's have have auto on-off or standby modes like I see on my subwoofer. I'm using 12v trigger signals from the Fosi Zd3 "preamp" to trigger the dual Za3s on and off, but I don't think they have auto on-off that triggers on signal detection.

Thanks for the info, I don't have anything with 12V Triggers so unless I change my whole setup; this won't work for me.

 

[SoySalsaPicante]

Thanks for the info, I don't have anything with 12V Triggers so unless I change my whole setup; this won't work for me.

Might a power-sensing smart strip like this work?

Amazon.com

 

[NBO]

What is your source? If you're listening to streaming audio, there are streamers with bass management and a sub out that would work fine before you get a signal out to the ZD3 & ZA3s.

Another option is a Fosi ZP3 preamp, which has adjustable high-pass filter. You can place one of these between the ZD3 and the ZA3s.

Thanks for that info. Didn't realize that about the Zp3. I might have chosen that at the beginning but didn't realize this. It'a actually cheaper for me to just to add a third Za3. I'll probably go that route because I've become attached to my Zd3 with it's digital volume readout and bluetooth reception. Of course, I could use a splitter on the Zd3 RCA outs sending one to the subwoofer and one through a home made HPF to the Za3. It's just too much fiddling. Fosi needs to include that Zp3 HPF option on new iterations of the Za3.

 

[Jimster480]

Might a power-sensing smart strip like this work?

Amazon.com

I thought about that, but usually audio components don't draw enough power. I would have to redo my entire setup to make this work in any fashion. It could be done though if I were to setup the audio components on the other plugs and leave the TV on the trigger plug.

 

[staticV3]

I thought about that, but usually audio components don't draw enough power. I would have to redo my entire setup to make this work in any fashion. It could be done though if I were to setup the audio components on the other plugs and leave the TV on the trigger plug.

FWIW, German brand Brennstuhl sell master slave power strips with a sensitivity knob.

You can dial that up until your master device's current draw will trigger it.

This only works if your slave devices turn on right away when given power though. No use if they go into Standby first.

 

[Jimster480]

FWIW, German brand Brennstuhl sell master slave power strips with a sensitivity knob.

You can dial that up until your master device's current draw will trigger it.

This only works if your slave devices turn on right away when given power though. No use if they go into Standby first.

Now that could work, I could use it for the DAC.

 

[NBO]

Wondering if this would be good for a set of Atmos channels? I was thinking to get this to power some Atmos channels that would sit on top of my RP-8000F II's and then I can use the sub output as well.
Does this amp have auto on-off? Right now I use 2x Fosi v3 Monoblocks for the speakers themselves. Don't want to add the Atmos channel on top of the other channels as I think it will reduce power output too much.

Hey Jimster,
I have to correct my earlier answer. The Za3 does have an auto off. If it doesn't detect a signal, it will shut itself off after about 10 minutes. That trickles down to anything slaved to it via the 12V triggers. At least that's true for bluetooth. Even if there is still a bluetooth connection, if there is no signal transmission, it shuts off. Takes about 10-15 minutes.

 

[Graham849]

Hey Jimster,
I have to correct my earlier answer. The Za3 does have an auto off. If it doesn't detect a signal, it will shut itself off after about 10 minutes. That trickles down to anything slaved to it via the 12V triggers. At least that's true for bluetooth. Even if there is still a bluetooth connection, if there is no signal transmission, it shuts off. Takes about 10-15 minutes.

NBO, I think you are confused. ZA3 has no Bluetooth. It is an amplifier only with rca in/ xlr inputs and a mono/stereo switch. On/off is controlled by pressing volume switch.

 

[Dennis_FL]

NBO, I think you are confused. ZA3 has no Bluetooth. It is an amplifier only with rca in/ xlr inputs and a mono/stereo switch. On/off is controlled by pressing volume switch.

It has a trigger for on/off. I had an amp which turned off when it sensed no input. Trouble is, when there was a silent or low volume passage, it would turn off. Really annoying with classical music.

 

[NBO]

NBO, I think you are confused. ZA3 has no Bluetooth. It is an amplifier only with rca in/ xlr inputs and a mono/stereo switch. On/off is controlled by pressing volume switch.

yep, I'm referring to the zd3 -- connected to my za3. Thanks

 

[multichannel_guy]

Is the GaN power supply not available as a cheaper bundle with either the Fosi ZA3 or V3 Mono?

 

[gekkekoe]

So I just got 2x za3 + zd3 and was testing it a bit. It does get a bit warm (after 2 hours non-stop running). See thermal images. Is this "luke-warm" ?
Obviously, stacking them makes the lower unit a bit warmer. The zd3 on the left is not warm at all.

 

[Jimster480]

So I just got 2x za3 + zd3 and was testing it a bit. It does get a bit warm (after 2 hours non-stop running). See thermal images. Is this "luke-warm" ?
Obviously, stacking them makes the lower unit a bit warmer. The zd3 on the left is not warm at all.
View attachment 470085
View attachment 470086

Yeah, they do run warm, but they are fine. It's well within the operating spec of the components. I would avoid stacking them just so that they run around the same temperature, but it's up to you.

 

[champ222]

Forgive me, i havent read all 42 pages of this.

I really like the look of the ZD3 DAC, it looks ideal for me.
I do feel like a version of the Fosi V3 mono, in the ZA housing, with no volume control (though not a deal breaker), with the 12v triggers would be a great option. the V3 mono gets better measurements than the ZA3 in stereo or mono, and the larger housing could make the V3 run a bit cooler.

It would make an awesome looking stack that would sound great. While a ZD3 and two V3 monos would do the job, the trigger from the DAC would be a nice addition, and visually, its a bit weird looking.

A matching CD player would be nice as well, even if it was just a transport with digital out to the DAC.

 

[Stereoed]

Hello, I bought two ZA3s from Fosi. I run them as monoblocks, each with a 48V 5A power supply. The op amps are the originals. I have to say the power and sound of the Fosis is really good. Since my Hifi Rose RA280 is being repaired and that could take 4 weeks, I thought about buying the Fosis as a temporary solution. I run them via XLR directly on the Eversolo A8. To switch on the ZA3, I used the 12V trigger via a Y-trigger cable. The ZA3s are set to maximum volume. When I switch on the A8, the ZA3s also switch on. But before the A8 has fully booted up, you can hear a loud pop from both speakers. The A8 doesn't do that with the Hifi Rose RA280. Can anyone help me figure out what that could be? Well, the Hifi Rose is an integrated amplifier. But I do find it strange, especially since the Eversolo has a preamp.