Fosi Audio ZA3 Stereo/Mono Amp Review – Making New Friends

INTRODUCTION

Courting inexperienced audio aficionados and maybe some seasoned people, the Fosi Audio ZA3 desktop amp has the attract of reasonably priced but buzz worthy tech. They have constructed an arsenal of small however mighty desktop energy amplifier options, from 2 channel, 3 channel and now a select-able two channel/monoblock constructed across the Texas Instruments TPA3255 class D amp chip.

By scaling again most energy, they can additionally run it in a decrease sign to noise ratio area that makes it clear and resolving on the similar time and delivering loads of energy for a desktop and even room filling output. However we must be practical concerning the 300W max energy output as the facility provide isn’t giant sufficient to ship true 300W steady energy output with the 32V maxing out at 160W or 240W for the 48V model.

Having experimented with the TB10D, and V3 amplifiers from Fosi Audio, the ZA3 is the subsequent era or third iteration of this design, each bettering on the subsequent because it ought to. The TB10D/BT20A Pro had been Gen1 utilizing the TPA3255 and had been probably the most highly effective model…till they launched the V3 with a 48V 5A energy provide possibility.

Technically you’ll be able to order the 48V 5A energy provide and use it with the TB10D Pro for extra energy with lowered sign to noise specs. Fosi Audio presents it with 32V/5A. 48V/5A or no energy provide choices priced at $129, $149 and $99 respectively.

FEATURE COMMENTARY

Ideally although the V3 was pretty effectively obtained minus some caveats, and the Fosi Audio ZA3 is a extra mature model with the stylistic parts of a burnt orange quantity knob, balanced inputs, a usable preamp and a mono mode to spice up energy output, or wastefully use it to energy a small subwoofer.

New options not accessible on their different fashions embrace the switchable RCA or XLR balanced enter that accepts ¼” TRS/XLR. With these two unbalanced and balanced connections you get two inputs. We are nonetheless caught with the tiny binding posts discovered on their different fashions, I have a tendency to make use of banana jacks for straightforward switching anyway.

Other new options embrace the subwoofer output, and 12V set off enter to robotically flip it on/off with a preamp or AVR? Another extra diy method for desktop PC customers could be to run a 12v out out of your desktop PC and set off it that approach. There are most definitely some DACs on the market with 12 set off outputs to show it on as effectively. I did check this with my historic Denon AVR-3806 and it is useful, let me clarify.

The Fosi Audio ZA3 powers on or off with an extended press on the amount knob, it appears delicate to the place you push on it, or it didn’t all the time acknowledge that I had tried to show it on. Maybe I used to be impatient, however generally I simply didn’t have the magic contact to show it on. I would favor a standalone energy swap if the knob goes to be sensitive. The knob itself is easy and the indentation is distinguished sufficient to see the place of it from throughout the room.

With the 48V 5A energy provide virtually as large because the amp itself, I felt snug taking this factor for a spin as the primary room amplifier and releasing it from pure desktop utilization. While it suits extra at residence there, it has loads of output to be the focus of a severe sound system.

The guide isn’t completely clear about loading the amp, it states 2-8 ohm speaker programs, I think about that is for stereo operation. To be secure, I’d not suggest utilizing a 2 ohm load in mono mode until Fosi Audio explicitly states it.

SOUND COMPARISONS

Pairing the Fosi Audio ZA3 with my Amrita Audio Elan 8 inch 2 approach flooring standers, the SMSL DO100 DAC, and Sony DVP-SS7700 it carried out reasonably exceptionally for a Class D chip amp. Imaging separation and readability had been fairly noteworthy. Bass management was tight, but maybe just a little restrained. This was not an absence of energy as I used to be working it at a good listening degree about 50% most clear output, as a substitute there was some richness lacking.

Swapping in a Parasound HCA800 II set to the identical degree, it sounded extra enveloping and the bass had extra texture and heat. More meaty and visceral sounding, I swapped within the Adcom GFA-545 once more performing some degree matching and seen it too had extra drive behind the bass.

Between these two amps, they each gave the look of stronger depth and extra envelopment. The Fosi Audio ZA3 had an outlined stage width with much less entrance to again vary, and the Parasound felt extra like an arcing stage versus a flat stage.

To be honest, these are some effectively regarded 2 channel amps with loads of energy provide and output present to energy the overwhelming majority of two channel sound programs into blissful happiness. Next I put it up towards the Denon AVR-3806, a decently highly effective residence theater receiver and it didn’t have the identical readability or decision of the Fosi Audio ZA3.

My ultimate check of the Fosi Audio ZA3 was to include the subwoofer pre-out. The addition of the subwoofer pre-out helps with the brand new wave of small bookshelf plus subwoofer setups. It is way simpler in a smaller room or desktop setup to make room for a bookshelf and offload the heavy lifting to the subwoofer on bass obligation.

The pre-out has a 200Hz low cross filter and is managed by way of the amount knob. The V3 pre-out was not a real pre-out, so Fosi carried out a correct and helpful characteristic. Note it may be used to complement the pure roll-off of your fundamental audio system, there isn’t any excessive cross filter for the primary channels and also you would wish to make use of the inbuilt crossover of your subwoofer to regulate it all the way down to a correct cut-off frequency.

MODDING AND HOT-RODDING

Op-amp swapping carries over from the V3 to the Fosi Audio ZA3. Removing 4 2mm hex screws (two on the again panel, two beneath), prying off the amount knob with a plastic cooking spatula, and loosening the 10mm nut offers you entry to the internals, which building reveals are miles and miles higher than a Dayton Audio DTA-100a I’ve from over a decade in the past.

The op-amps are used within the pre-amplification phases and supply achieve and suggestions management to attenuate distortion. There are a complete of 5 op-amps that may be swapped, one for every Left/Right, two for the subwoofer pre-out (one is used for the filter), and one for the XLR.

They come inventory with TI NE5532 which is classic by audio requirements, however an especially secure, cheap, noise free op-amp present in hundreds of thousands of audio gadgets together with skilled audio gear.

FOSI AUDIO ZA3 Internal Design — Fosi Audio ZA3 Internal Design.

Other boutique op-amps might be swapped in, however including new ones might not all the time be a fantastic thought or assure “higher” efficiency. It is pretty simple for some quicker op-amps to turn out to be unstable and oscillate within the flawed scenario, or maybe they can not drive the load, or the achieve isn’t structured accurately to attenuate distortion.

The excessive value tags of different op-amps could be a results of low use so it doesn’t profit from financial system of scale, or simply flat out as a result of they’ll. I occur to have 4 BB ones starting from the OPA2134PA, 2227P, 2228P and 2107AP from an Audiotrak Prodigy soundcard experiment.

I’d examine in a separate evaluation if I discover it attention-grabbing sufficient, a few of them may add noise or trigger instability and I want to measure the results if attainable utilizing my restricted measurement tools. The heatsink + energy resistors would most definitely overheat when distortion parts, I really want to deliver out my water heater aspect load to deal with the facility higher.

Bipolar, FET and discrete op-amps can behave in a different way as effectively so with out correct testing tools, you may introduce some coloration into your audio chain. There was once nice data by Douglas Self over a decade in the past, however there are additionally many different nice sources (59+ op amps examined ) discovered all through the web or in books.

You may simply take the spiritual route and simply consider. I can totally admire how exhausting it’s to take away sighted bias from testing, and the way quick our reminiscence is that if not performing fast adjustments to check.

FINAL REMARKS

I did check it in mono mode whereas I did some house responsibilities, and it by no means acquired too heat or shut down. I used to be not stress testing, however I really feel assured that the Fosi Audio ZA3 handles mono hundreds simply tremendous and so they increase a 240W energy ranking right into a 4 ohm load. Get two and run them as monoblocks and have final channel separation.

Channel separation is the noise of 1 channel bleeding into the opposite channel in case you had been unaware. One lacking characteristic is a quantity management bypass for the twin mono people, however max them out and let it rip by way of one other pre-amp gadget, DAC or streamer.

One characteristic lacking is maybe a phono enter for the resurgence of vinyl. It’s not a should have characteristic, as these actually into vinyl may want to make use of a standalone phono preamp of their selecting anyway. Other folks may want bluetooth enter as a substitute, an excellent DAC or preamp may embrace these options individually, I take pleasure in this as simply an amp.

Class D is basically a motor management circuit design tailor-made to satisfy the audible audio frequency spectrum necessities, and audio system share similarities to motors in {that a} coil of wire is worked up by way of a magnetic area. There needs to be no worry in utilizing fashionable Class D amps and dropping constancy. While variations had been famous between full fledged bigger brethren, I’ve minor qualms in recommending the Fosi Audio ZA3 amplifier.

While the V3 is on mortgage to Loomis I’m unable to instantly examine, I consider the ZA3 phases nearer to the Adcom and Parasound than the V3 did. It does a greater amplification job than an AVR and it appears modern on a desktop being loads highly effective in a nearfield setup.

Disclaimer: Fosi Audio fortunately offered this free of charge and this evaluation was not written by robots.

FOSI AUDIO ZA3 SPECIFICATIONS

Chip Set Texas Instruments TPA3255
Output Power With 48V/5A PSU
Stereo: 155Wx2 @4Ω
Mono: 235Wx1 @4Ω
With 32V/5A PSU
Stereo: 95Wx2 @4Ω
Mono: 110Wx1 @4Ω
Terminating Impedance 2-8Ω
Input Mode RCA, XLR, 1/4″ TRS
Output Mode Speaker Output (helps banana plug or naked wire connection), Active Subwoofer Output
Frequency Range 20Hz – 20KHz(±0.1dB)
SINAD 89dB
THD ＜0.006%
SNR ≥106dB
Dynamic Range ≥106dB
Device Dimension 15.49 x 18.39 x 5.08 cm; 1.78 Kilograms
DC Input Range 24-48V
Power Supply 32V/5A, 48V/5A