• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Sabaj A30a announced

Just for my curiosity, is there anyone with engineering skills who can explain to me the source of heat in this kind of digital amp?
It’s usually idle losses, and since these amps don’t have any heat sinks all heat is dumped into the enclosure, which is less efficient as radiating the heat away and therefore gets relatively hotter.
 
A30A gets quite hot after a few hours, even if not working, but last weekend I was away from home and forgot to turn it off so I was very concerned about it.
Surprisingly, after three full days the temperature was apparently the same, it's hot but not untouchable, if I must guess I'll say like 45 to 50 Celsius degrees, maybe 60-ish at worst.
Just for my curiosity, is there anyone with engineering skills who can explain to me the source of heat in this kind of digital amp?
My former class AB amps were not this warm when they were switched on but not in use, the only one that had similar behaviour was heavily biased towards class A, so I sold it because I don't like to waste so much energy (and paying for it).

By the way, when the A30A is hot, it sounds way better, and I'm still impressed by the quality of this amp, so impressed that I suddenly stopped reading reviews of other equipments in the last months, it was a long journey, almost 20 years since my first encounter with a Tripath TA2024, but I think I've finally found my ideal cheap way of listening to music with pleasure.
I had to laugh out loud when I read your post, but you're right, amplifiers need a certain base temperature for a good sound.

You don't need to worry about the heat, as long as you can put your hand on it for a few seconds, it won't get over 40 degrees.
40-55 degrees is normal for amplifiers, and even more under high load. The A30a has no real heat sinks and dissipates all the heat generated through the closed housing. The heat when idle is caused by all components, especially the switching power supply, but it's not a lot of power that's being used.

Your old A/B amplifiers probably used x times more power, but dissipated it through large heat sinks.
 
Update on my return and refund of the Sabaj A30a, I have now received the refund for the amp (445$), however I have not been refunded for the two return postages to their Belgium warehouse (2x43,90€), despite Hifi-Express claiming on their site that they will cover return postage when the amp is faulty, which I think we all agree that they were.

All in all this little experiment has cost me 100€ (return postage and currency conversions) with nothing to show for it except lots of wasted time. I accept that there is always a risk when buying from China but I thought Hifi-Express would be a little more credible than an average Aliexpress store, unfortunately I can report that they are not and I would discourage you from buying from them. Better stick to Amazon when buying anything more expensive Chinese audio products.

I will edit this post IF Hifi-Express bother to refund my shipping costs as per their return policy on their site: "For items that are damaged, incorrect, or faulty upon delivery, Hifi-express will cover the shipping cost."
 
Last edited:
Update on my return and refund of the Sabaj A30a, I have now received the refund for the amp (445$), however I have not been refunded for the two return postages to their Belgium warehouse (2x43,90€), despite Hifi-Express claiming on their site that they will cover return postage when the amp is faulty, which I think we all agree that they were.

All in all this little experiment has cost me 100€ (return postage and currency conversions) with nothing to show for it except lots of wasted time. I accept that there is always a risk when buying from China but I thought Hifi-Express would be a little more credible than an average Aliexpress store, unfortunately I can report that they are not and I would discourage you from buying from them. Better stick to Amazon when buying anything more expensive Chinese audio products.

I will edit this post IF Hifi-Express bother to refund my shipping costs as per their return policy on their site: "For items that are damaged, incorrect, or faulty upon delivery, Hifi-express will cover the shipping cost."
Did they agree that the amps were faulty? Did they inform you if they could confirm the behaviour you observed?
 
Update on my return and refund of the Sabaj A30a, I have now received the refund for the amp (445$), however I have not been refunded for the two return postages to their Belgium warehouse (2x43,90€), despite Hifi-Express claiming on their site that they will cover return postage when the amp is faulty, which I think we all agree that they were.

All in all this little experiment has cost me 100€ (return postage and currency conversions) with nothing to show for it except lots of wasted time. I accept that there is always a risk when buying from China but I thought Hifi-Express would be a little more credible than an average Aliexpress store, unfortunately I can report that they are not and I would discourage you from buying from them. Better stick to Amazon when buying anything more expensive Chinese audio products.

I will edit this post IF Hifi-Express bother to refund my shipping costs as per their return policy on their site: "For items that are damaged, incorrect, or faulty upon delivery, Hifi-express will cover the shipping cost."
It's a real shame that you received two defective devices one after the other. As a manufacturer, I would have checked the replacement device three times and tested it thoroughly. So far, there have been no known defects or failures.
I hope that HiFi-Express will reimburse you for the shipping costs, that would be the least they could do.

Did they agree that the amps were faulty? Did they inform you if they could confirm the behaviour you observed?
@Nahkarankaisija has written and proven everything about it on the last 6 pages, you can simply read it.
 
Hifi-Express has tested the 2nd amp on their own equipment without any noise issues, they are also testing the other amp. I really have no idea what could cause the buzzing noise issue in my setup outside of a design flaw, I have tested two other amplifiers after the Sabaj without any issues. So looks like the amps themselves may not be "faulty" and I will be out of pocket for the return costs.
 
Hifi-Express has tested the 2nd amp on their own equipment without any noise issues, they are also testing the other amp. I really have no idea what could cause the buzzing noise issue in my setup outside of a design flaw, I have tested two other amplifiers after the Sabaj without any issues. So looks like the amps themselves may not be "faulty" and I will be out of pocket for the return costs.
The direct conversion of the audio signal into PWM is very special and works very differently than all other Class D amplifiers.
We have several customers who use our high-energy products in industry with PWM. I know that special and very interference-resistant switching power supplies have been developed for these applications.
You may have a special interference in your power grid that collided with the PWM technology and triggered this. But even then it would be a fault in the device, because something like this has to be intercepted.
 
A30A gets quite hot after a few hours, even if not working, but last weekend I was away from home and forgot to turn it off so I was very concerned about it.
Surprisingly, after three full days the temperature was apparently the same, it's hot but not untouchable, if I must guess I'll say like 45 to 50 Celsius degrees, maybe 60-ish at worst.
Just for my curiosity, is there anyone with engineering skills who can explain to me the source of heat in this kind of digital amp?
My former class AB amps were not this warm when they were switched on but not in use, the only one that had similar behaviour was heavily biased towards class A, so I sold it because I don't like to waste so much energy (and paying for it).

By the way, when the A30A is hot, it sounds way better, and I'm still impressed by the quality of this amp, so impressed that I suddenly stopped reading reviews of other equipments in the last months, it was a long journey, almost 20 years since my first encounter with a Tripath TA2024, but I think I've finally found my ideal cheap way of listening to music with pleasure.
My Sabaj A30a runs warm but not hot (I must say I cannot play music at high volume since I live at the second floor of a 6 storey building). A few day ago I rudimentarily measured the temperature of the alluminum case with a remote sensor (the small white box on the left) in two different positions (indicated by the red arrows) while playing music at medium-moderate volume (around 65-68 dB at 3 meters, speaker sensitivity = 85dB) and it remained at 31,5°C for about 2 and a half hours. I guess this is a bit underestimated since the sensor is for measuring air temperature.

screenshot_869.jpg
 
I didn't realize until today that Axign has been acquired last February by Monolithic Power Systems, a company that until now had not focused on audio applications. I don't know if this is a good news regarding the future of Post-Filter Feedback using the Axign Technology as the one implemented in the SabajA30a with the
AX5689 chip. I'm actually surprised that so far no major brand (other than SLSM/Sabaj and maybe Harman Kardon) has implemented this technology in their amplifiers. It doesn't seem to be too complex or expensive and the results obtained so far are quite exciting (maybe there is a problem of compatibility with the power stages used by most vendors).
 
Last edited:
I didn't realize until today that Axign has been acquired last February by Monolithic Power Systems, a company that until now had not focused on audio applications. I don't know if this is a good news regarding the future of Post-Filter Feedback using the Axign Technology as the one implemented in the SabajA30a with the AX5689 chip.
Well, now you can buy the chip off-the-shelf and make one yourself. :p

Monolithic do make some class-D amp chips, and the product page for the AX5689 was updated to reference them.

Shortly after the acquisition they did a couple of promotional webinars (intro, deep dive) and the slides state "More MPS Axign products are in development". That's not a bad sign...
 
Are there any measurements now?
I would be particularly interested in the dac
 
It has now been one month after the last reply from Hifi-Express where they said they would test the returned amplifiers in their factory, I have sent several emails since then asking for updates with total radio silence from them. It is not looking good for my chances to receive any compensation from them, so I have told them in my latest email that I would accept partial refund for only half of the shipping costs I paid, but it feels like squeezing blood from a stone trying to deal with them.

As always, buyer beware when buying from a Chinese shop and particularly from Hifi-Expressen, dont expect any support or customer service.
 
Are there any measurements now?
I would be particularly interested in the dac
There is no DAC in the device. The device works entirely digitally and converts directly to PWM at the output. Therefore, the amplifier has an ADC on the analog input that converts directly to digital.

For measured values, take a look at the test for the SMSL VMV A2 here in the forum; these should hardly differ.
 
Now I see... The AX5689 is an audio converter and amp controller.
 
OMG. If indeed the STA309A
is used, I wonder what the Loudness 1-16 programs are all about?
Automatic volume controlled loudness? Is this comparable to the loudness correction in APO EQ (ISO 226 2003)?


ioioio.JPG
 
Last edited:
OMG. If indeed the STA309A
is used, I wonder what the Loudness 1-16 programs are all about?
Automatic volume controlled loudness? Is this comparable to the loudness correction in APO EQ (ISO 226 2003)?

@ZolaIII


View attachment 378745
Only a few functions of the STA309A are used, and the "Automatic volume controlled loudness" is not one of them.
You can use the 32 EQ profiles (they are just presets) of the STA309A, but you don't have to.

What is unfortunately still unclear is the volume control. If the volume control is done in the STA309A and not in the AX5689, that would be a disadvantage and a real shame.
 
Final reply from me to this thread, I have been ghosted by both the email addresses listed on Hifi-Express so it is clear that Hifi-Express does not honor their terms listed on their website. It is not worth my time trying to argue with sketchy Chinese people so I will take this as a lesson learned and won't buy Chinese hifi ever again, atleast not from China directly.
 
Last week I received the Wiim Ultra as an upgrade from my Wiim Pro Plus. The Pro Plus was set to fixed volume and connected to the Sabaj via Toslink. In the new setup the Wiim Ultra acts as a preamp (variable volume), is connetcet to the Sabaj via Coax, and I keep the Sabaj volume fixed at 80 (as if it were a power amp). The subwoofer (a Martin Logan Dynamo 700w) is now driven by the Wiim Ultra which, compared to the Sabaj, has the ability to select a crossover frequency lower than 70Hz (down to 30Hz). This provides a more suitable setup when I want to use the sub with my Elac Carina FS 247.4 towers (40-50Hz crossover). When playing music with the other pair of speakers I have, the Elac Vela BS403, I find a crossover frequency of 70Hz to be ideal. Overall I am very happy with both the Sabaj A30a and the Wiim Ultra, obviously the Ultra being the new "toy" I think it sounds better than the Wiim Pro Plus but I am fully aware that is just my imagination (both streamer are fully transparent both when digitally connected to the amp or when using the analog output of their DACs). For around €/$ 800 the Sabaj A30a/Wiim Ultra combo is VERY hard to beat. My only concern is leaving the Sabaj with the volume set to 80, if something goes wrong with the Wiim volume when I turn it on I could risk blowing my speakers.

IMG_20240828_120913.png
 
Back
Top Bottom