DIY Mono Amplifier Build with 3e Audio 480-1-29A and MicroAudio SMPS600-R3

[Kanaz]

Hi everyone,


I wanted to share my updated DIY mono amplifier build using the 3e Audio 480-1-29A amplifier module with the MicroAudio SMPS600-R3 power supply.


I previously built a similar amplifier using a Mean Well UHP-series power supply, and that build worked well overall. However, I had one issue: when turning the amplifier off, there was a fairly noticeable pop noise.


With the MicroAudio SMPS600-R3, the behavior is much better.


It seems to have a soft-start / standby-type control behavior. When turning the amplifier off via the SWT connector, the amplifier module does not shut down abruptly. Instead, it seems to power down more gradually after a short delay.


Because of this, the turn-off pop noise is almost completely gone. I can only hear a very tiny sound if I put my ear very close to the speaker.


MicroAudio also confirmed to me that it is okay to leave the power supply working in standby mode. So in my current setup, I keep AC power connected and use the SWT connector for ON/OFF operation.


I have seen different reports about pop noise with the 480-1-29A module. Some users say they have no pop noise at all, while others seem to experience it. In my case, I recently bought eight 480-1-29A modules, and with my normal power supply arrangement, all of them produced a pop noise when switched off.


Because of that, I would normally need to add an external relay circuit. But with the MicroAudio SMPS600-R3, I do not feel that a separate relay is necessary.

Parts used​

• Amplifier module: 3e Audio 480-1-29A
• Power supply: MicroAudio SMPS600-R3
• AC inlet: Furutech FI-06(R) NCF
• RCA input connector: Furutech FT-903(G)
• XLR chassis connector: NEUTRIK NC3FD-LX-HE
• Binding posts: Monosaudio BP451G
• Power switch: NKK S331
• Power LED: BIWAR MPC6-1WD12V
• AC internal wiring: Oyaide 3398-16
• DC wiring from PSU to amplifier module: Oyaide 3398-14
• Speaker output wiring from 480-1-29A to binding posts: Oyaide EXPLORER V2 2.0 sq

I also installed NEUTRIK NC3FD-LX-HE XLR chassis connectors on the amplifier chassis. However, my current DSP only supports RCA outputs, so the XLR connectors are installed mechanically but are not wired internally at the moment.

About the 3e Audio modules​

I should also mention my recent experience with 3e Audio.


Recently, I bought two additional 480-1-29A modules. Before placing the order, I specifically asked them to send modules with the same capacitors, because I did not want mixed capacitors in a mono-mono stereo system. They replied that this would be okay.


However, when I received the modules, one had Rubycon capacitors and the other had KYB capacitors. I requested an exchange, but they refused and repeatedly said that there was no problem because the capacitance values were the same.


Technically, that may be true. But personally, for a mono-mono stereo system, I did not want the left and right amplifier modules to use different capacitors. I explained this, but my request was not accepted.


The response time was also quite slow. To be honest, I was disappointed, especially because I had already bought eight 480-1-29A modules and also two A7 Mono amplifiers from them.


I also bought a pair of 3e Audio A7 Mono amplifiers recently, and one unit included a user manual while the other did not. This made me feel that their overall QC and packing consistency could be improved.


In the end, I bought additional Rubycon capacitors myself. Since I was replacing them anyway, I chose a higher-spec Rubycon version with 1800 µF capacitance and replaced the capacitors myself so that the left and right amplifier modules would match.

About MicroAudio​

My experience with MicroAudio was completely different.


Even before purchasing, I exchanged several emails with Sami at MicroAudio. He shared photos of the SMPS production process and allowed me to choose between several small configuration options and fine adjustments.


I was very impressed by his kindness, speed, and the way he handled communication.


Even after I received the power supplies, he continued to check in with me. He asked whether the products had arrived safely, whether I had completed the amplifier build, and whether there were any problems after assembly. Even when I did not reply immediately, he followed up to make sure everything was okay.


This level of support was genuinely impressive.

Sound and usability impressions​

As expected, the amplifier built with the Mean Well power supply and the amplifier built with the MicroAudio power supply feel different in actual use.


The biggest difference for me is not only the sound impression, but also the usability: standby operation, turn-off behavior, and pop-noise control are much better with the MicroAudio SMPS600-R3 in my build.


Of course, this is not a measurement-based review, and I understand that some ASR members may not like this kind of subjective impression. But as a DIY builder, I am very satisfied with the result.


The amplifier is clean and quiet in my system. There is no audible hiss, no significant pop noise, and the amplifier is comfortable to use.


As you can see from my photos, I originally liked vintage speakers and tube amplifiers. However, I do not have a fixed bias against modern measured-performance-based audio. These days, I am also building a speaker system based on many ASR-style reviews and measurements, and I am enjoying it very much.


Overall, I am very happy with the MicroAudio SMPS600-R3 in this DIY amplifier build.


I plan to do more DIY builds using MicroAudio products in the future, and I will post another review after my next project.


Thanks for reading.

 

[101geo]

+1 for the praise of Sami. A true gent.

 

[maxchau]

I also bought two 480-1-29a and two 260-2-29a boards recently. The former are powered by 500W toroidal transformers at 37VDC. No pop noise turning on-off. The later are powered by one 600W Meanwell LOP-600-36. In both cases, there is no popping noise on or off. Could this related to the use of lower voltage (36V)? Or, the use of 10K passive pot?

 

[Redacted]

Anyone without one might buy a 'scope - always useful. Mine was £26 on AliX - crazy cheap, but good enough for casual debug.