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Loxjie A30 Amplifier Review

MattG

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Apologies, slightly off-topic, but I mentioned this earlier in the thread, and there seemed to be a little interest...

It's a pretty cool chip! I'm actually planning to use the "P" version to build a DIY "sound server" for my office. In a single fairly small enclosure, I'll have a power supply, Raspberry Pi, and MA12070P board. I can send audio over the network to the RPI (e.g. from my PC) via PulseAudio, and the RPI can send audio data via I2S straight to the MA12070P chip. I can also do digital volume control, change power management profiles, and some other fun stuff via I2C serial command from the RPI to the chip. Still waiting for all the parts to arrive, so only at the planning stage, but I expect to get something working fairly quickly.

@MattG
This could be quite an interesting project!
Do you plan to document it in any way? Opening a new thread here or in any other forum (DYIAudio, etc.)?
Please, keep us informed!

I now have a working Raspberry Pi + ma12070p-based sound server. The gist is described above, literally just a Raspberry Pi and an ma12070p amp board (and power supply). Audio is sent to the device over the network via PulseAudio. Merus/Infineon actually provide a native Linux driver for the ma12070p which exposes a number of controls and status through ALSA (I originally thought I'd be hacking my own I2C code to do this, but having it all pre-made was a nice perk).

I started by using the Infineon ma12070p reference board for the prototype concept. See here. The reference board is barely bigger than a postage stamp! I ran with this for a while without issue, and went ahead and designed my own ma12070p board. I built up my board last weekend, and it's been running successfully since. See here. I just placed a parts order for a "version 2" of my board, which is basically just a physically larger board that allows the use of overkill RLC output filter components along with a couple other small tweaks.

I'm not sure how one would go about measuring the performance of this design, since the "input" isn't the typical USB/SPDIF/TOSLINK, but rather an application-specific protocol (i.e. PulseAudio's wire format). Assuming I didn't make any design errors, it "should" have measured performance consistent with what's shown in the ma12070p datasheet. This is based on the fact that the design is a literal copy of the reference board (with the addition of the RLC output filter). Subjectively, I have no complaints with the sound. I'm using this in my office to drive a pair of Solstice MLTL speakers. But I fully admit to a definite "baby bias" on stuff I built myself! :)
 

fluxcapacitor

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Hi, I'm new to the forum. Got here looking for a small amp/DAC for my desk speaker as the old amp was breaking down. With some googling I landed here and found this nice loxjie A30. Got mine a month ago and really like it so far. Though I don't consider my self a audiophile nor am I actually listening to that much music. But I built my own speakers and I'm quiet interested in the technical aspects of audio.
So I had the itch to know what the A30 looks like on the inside.

Though some of you might also curious so here are some pictures.

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i was looking for these photos for a long time, thanks for the good work :)
 

BeerBear

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Someone on Amazon complained about hiss with this amp. Did anyone else notice hissing, either from the speakers or headphones?

How about the unit itself (including the power brick)? Is it silent or does it produce any noise, like coil whine and such?
 

boselover61

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Someone on Amazon complained about hiss with this amp. Did anyone else notice hissing, either from the speakers or headphones?

How about the unit itself (including the power brick)? Is it silent or does it produce any noise, like coil whine and such?
If you put this near another amplified product it will hiss. I had this placed on top of my active subwoofer and it whines like crazy. Moved it to an isolated area and it's gone.
 

escape2

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If you put this near another amplified product it will hiss. I had this placed on top of my active subwoofer and it whines like crazy. Moved it to an isolated area and it's gone.
Glad I didn't go with the A30 as I keep my amp directly on top of my sub.
 

boselover61

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Why?

This is for nearfield/desktop application, so neither the sub nor the amp have to work hard.
No it's just i'm not sure if there's moving parts inside the amp. If there's moving parts and you place them on top of the woofer playing loud it can damage the amp
 

Toku

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Why?

This is for nearfield/desktop application, so neither the sub nor the amp have to work hard.
The A30's speaker output omits a filter that prevents the emission of high frequency noise.
As a result, it radiates strong electromagnetic noise into the surrounding space and interferes with nearby electronic devices.
 

ctakim

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Someone on Amazon complained about hiss with this amp. Did anyone else notice hissing, either from the speakers or headphones?

How about the unit itself (including the power brick)? Is it silent or does it produce any noise, like coil whine and such?
No hissing from my unit, on my computer desktop next to a 34" monitor and an Amazon Echo show.
 

BeerBear

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If you put this near another amplified product it will hiss. I had this placed on top of my active subwoofer and it whines like crazy. Moved it to an isolated area and it's gone.
The A30's speaker output omits a filter that prevents the emission of high frequency noise.
As a result, it radiates strong electromagnetic noise into the surrounding space and interferes with nearby electronic devices.
Interesting. I was thinking of using it on my desk and putting my USB sound card right on top of it. But maybe this would be problematic...
Is this a thing with all digital/class D amps?

No hissing from my unit, on my computer desktop next to a 34" monitor and an Amazon Echo show.
Yeah, I suppose it depends on the specific setup and the devices involved.
 

somebodyelse

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Interesting. I was thinking of using it on my desk and putting my USB sound card right on top of it. But maybe this would be problematic...
Is this a thing with all digital/class D amps?
It's implementation specific, rarely measured in reviews, and not necessarily a problem. It's usually discussed at least briefly in the chip manufacturers' datasheets and application notes, and some include specific measures that are recommended in particular circumstances. See also the 'Class D and EMI' section in https://www.hypex.nl/img/upload/doc/an_wp/WP_AES123BP_the_engineers_survival_guide.pdf starting page 124. Most of the considerations apply equally to switching power supplies like the power bricks and phone chargers used by many products.
 

Toku

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Interesting. I was thinking of using it on my desk and putting my USB sound card right on top of it. But maybe this would be problematic...
Is this a thing with all digital/class D amps?
You won't know until you try to interfere with your planned USB sound card.

Such a design is common to amplifiers using the MA12070 chip manufactured by the SMSL Group.
SMSL SA300, SMSL DA-8s, SABAJ, A10a, and Loxjie A30.
The main amplifier section of these products has the same circuit design.
Other class D amplifiers except these have built-in output filters.
This filterless design is due to the fact that chip maker Infineon is appealing the filterless design of the MA12070's output.

In the EU area, the EMC standard strictly regulates the problem of such electromagnetic interference. There are restrictions on the EMI on the disturbing side and the EMS on the disturbing side. Search for EMC EMI EMS for more information.
 

Factory Team Gair

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Thanks to Amir and Zeos I have radically changed my system to fit my needs better.
I bought a Loxjie on ebay (probably from someone here or a zeos viewer) since in late March none were available retail. Not too bad of a gouging price, thanks guy.
Anyway I had a Yamaha tsr-7850 + Jamo s803 5.0 + atmos speakers for a 7.1.2 setup that i liked sometimes. Wife did not like it,cat no like, neighbor no like at decent volumes. So I never really got to use it. The living room is smallish too. As a test I deleted all the surround speakers from the Yamaha menu and watched Beverly Hills Cop in 2.1, and it was amazing, soundtrack was a pleasure to listen to, dialog was easy to understand, and there were occasional and appropriate "surround sound " effects sometimes! At the time I wasn't sure if it was my bias, or that an old movie was geared towards simpler audio, or that it just worked that well. Several days of movies, Netflix, and Spotify later with the Yamaha 2.1 and now the Loxjie a30 has me set on 2.1 for my main audio for now. Everything just sounds more clear and natural. After months of goofing around with the ypao, manual settings, speaker replacement and placement, I never did truly love the experience. Dialog was the worst, often not loud enough and or sounding strained, and then soundtrack or effects would swoop in and crush it. Maybe it was the environment and the wife/neighbor constraints, maybe it was the surrounds and Jamo s 81 center not keeping up with the s 803, my settings/setup, idk.

I do know that the Loxjie a30 + s 803 set up in place now has beautiful and balanced music, soundtrack, and dialog presentation that pleases the whole family. It is also insane getting rid of 7 speakers, 7 runs of wire, and clearing off cubic feet of space off the entertainment center. So much cleaner setup without losing capabilities that we care about. The loxjie has no problem filling the room due to their output and the size of the room.

Thanks again Amir, reviewers, and people here asking questions and giving inputs, it helped me greatly.

Pros:everything
Cons: with my head down near the power brick to hook things up, I heard it squealing a little, not audible at any other distance.
 

AdamG

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Thanks to Amir and Zeos I have radically changed my system to fit my needs better.
I bought a Loxjie on ebay (probably from someone here or a zeos viewer) since in late March none were available retail. Not too bad of a gouging price, thanks guy.
Anyway I had a Yamaha tsr-7850 + Jamo s803 5.0 + atmos speakers for a 7.1.2 setup that i liked sometimes. Wife did not like it,cat no like, neighbor no like at decent volumes. So I never really got to use it. The living room is smallish too. As a test I deleted all the surround speakers from the Yamaha menu and watched Beverly Hills Cop in 2.1, and it was amazing, soundtrack was a pleasure to listen to, dialog was easy to understand, and there were occasional and appropriate "surround sound " effects sometimes! At the time I wasn't sure if it was my bias, or that an old movie was geared towards simpler audio, or that it just worked that well. Several days of movies, Netflix, and Spotify later with the Yamaha 2.1 and now the Loxjie a30 has me set on 2.1 for my main audio for now. Everything just sounds more clear and natural. After months of goofing around with the ypao, manual settings, speaker replacement and placement, I never did truly love the experience. Dialog was the worst, often not loud enough and or sounding strained, and then soundtrack or effects would swoop in and crush it. Maybe it was the environment and the wife/neighbor constraints, maybe it was the surrounds and Jamo s 81 center not keeping up with the s 803, my settings/setup, idk.

I do know that the Loxjie a30 + s 803 set up in place now has beautiful and balanced music, soundtrack, and dialog presentation that pleases the whole family. It is also insane getting rid of 7 speakers, 7 runs of wire, and clearing off cubic feet of space off the entertainment center. So much cleaner setup without losing capabilities that we care about. The loxjie has no problem filling the room due to their output and the size of the room.

Thanks again Amir, reviewers, and people here asking questions and giving inputs, it helped me greatly.

Pros:everything
Cons: with my head down near the power brick to hook things up, I heard it squealing a little, not audible at any other distance.
Welcome Aboard @Factory Team Gair.
 

fluxcapacitor

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Thanks to Amir and Zeos I have radically changed my system to fit my needs better.
I bought a Loxjie on ebay (probably from someone here or a zeos viewer) since in late March none were available retail. Not too bad of a gouging price, thanks guy.
Anyway I had a Yamaha tsr-7850 + Jamo s803 5.0 + atmos speakers for a 7.1.2 setup that i liked sometimes. Wife did not like it,cat no like, neighbor no like at decent volumes. So I never really got to use it. The living room is smallish too. As a test I deleted all the surround speakers from the Yamaha menu and watched Beverly Hills Cop in 2.1, and it was amazing, soundtrack was a pleasure to listen to, dialog was easy to understand, and there were occasional and appropriate "surround sound " effects sometimes! At the time I wasn't sure if it was my bias, or that an old movie was geared towards simpler audio, or that it just worked that well. Several days of movies, Netflix, and Spotify later with the Yamaha 2.1 and now the Loxjie a30 has me set on 2.1 for my main audio for now. Everything just sounds more clear and natural. After months of goofing around with the ypao, manual settings, speaker replacement and placement, I never did truly love the experience. Dialog was the worst, often not loud enough and or sounding strained, and then soundtrack or effects would swoop in and crush it. Maybe it was the environment and the wife/neighbor constraints, maybe it was the surrounds and Jamo s 81 center not keeping up with the s 803, my settings/setup, idk.

I do know that the Loxjie a30 + s 803 set up in place now has beautiful and balanced music, soundtrack, and dialog presentation that pleases the whole family. It is also insane getting rid of 7 speakers, 7 runs of wire, and clearing off cubic feet of space off the entertainment center. So much cleaner setup without losing capabilities that we care about. The loxjie has no problem filling the room due to their output and the size of the room.

Thanks again Amir, reviewers, and people here asking questions and giving inputs, it helped me greatly.

Pros:everything
Cons: with my head down near the power brick to hook things up, I heard it squealing a little, not audible at any other distance.
good for you, i'm also waiting for re-stock of A30 to order.You were lucky, it's out of stock everywhere i look for.
 

ctakim

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Thanks to Amir and Zeos I have radically changed my system to fit my needs better.
I bought a Loxjie on ebay (probably from someone here or a zeos viewer) since in late March none were available retail. Not too bad of a gouging price, thanks guy.
Anyway I had a Yamaha tsr-7850 + Jamo s803 5.0 + atmos speakers for a 7.1.2 setup that i liked sometimes. Wife did not like it,cat no like, neighbor no like at decent volumes. So I never really got to use it. The living room is smallish too. As a test I deleted all the surround speakers from the Yamaha menu and watched Beverly Hills Cop in 2.1, and it was amazing, soundtrack was a pleasure to listen to, dialog was easy to understand, and there were occasional and appropriate "surround sound " effects sometimes! At the time I wasn't sure if it was my bias, or that an old movie was geared towards simpler audio, or that it just worked that well. Several days of movies, Netflix, and Spotify later with the Yamaha 2.1 and now the Loxjie a30 has me set on 2.1 for my main audio for now. Everything just sounds more clear and natural. After months of goofing around with the ypao, manual settings, speaker replacement and placement, I never did truly love the experience. Dialog was the worst, often not loud enough and or sounding strained, and then soundtrack or effects would swoop in and crush it. Maybe it was the environment and the wife/neighbor constraints, maybe it was the surrounds and Jamo s 81 center not keeping up with the s 803, my settings/setup, idk.

I do know that the Loxjie a30 + s 803 set up in place now has beautiful and balanced music, soundtrack, and dialog presentation that pleases the whole family. It is also insane getting rid of 7 speakers, 7 runs of wire, and clearing off cubic feet of space off the entertainment center. So much cleaner setup without losing capabilities that we care about. The loxjie has no problem filling the room due to their output and the size of the room.

Thanks again Amir, reviewers, and people here asking questions and giving inputs, it helped me greatly.

Pros:everything
Cons: with my head down near the power brick to hook things up, I heard it squealing a little, not audible at any other distance.
Glad you like the A30. I'm using it as a computer desktop USB DAC/Amp for a 2.1 setup and it seems ideal for such a system. Not sure I want to give up my 5.1 home theater set up as you did, but glad that you are happy. I'm thinking more about going in the opposite direction with 7.2 plus Atmos, but I've not decided yet. Plus all the AV Pre-/Pros that Amir has tested have done rather poorly, sad to say.
 

kernelpanic

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Was there ever confirmation if the analog inputs are digitized? I see there are EQ modes so I'm going to assume the answer is yes?
 

Toku

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Was there ever confirmation if the analog inputs are digitized? I see there are EQ modes so I'm going to assume the answer is yes?
The A30 combines the amplifier chip of the MA12070 with the electronic volume of the NJW1194.
NJW1194 is an analog type electronic control volume IC. The ladder resistor is used for the volume circuit.
The A30 does not have an EQ function. In addition to volume control, the NJW1194 also has an analog type tone control built-in. The only feature you think of as an EQ is the pre-made preset values for this tone control.

At first glance, the A30 seems to have a built-in digital volume and digital EQ, but it is all made of analog circuits. It's just a digital control of those settings.
 
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