Our newly developed mid-range music server, AAMS S, uses hybrid power supply topology of SMPS with post linear voltage regulators. We will demonstrate the prototype during WAVE 2026. We invite you to visit us and listen.
Our Motivation
We were intrigued when a leading music server maker from down under moved away from LPSU to hybrid SMPS with multi-level post regulation. Designing SMPS is a lot harder than designing linear PSU, so our approach is to buy readily available SMPS for our application and design our own post-SMPS linear voltage regulator board as the ATX power supply.
Our Approach
We explored the idea of developing something like PicoPSU but with higher quality DC-DC step-down converters. Analog Devices regional Field Application Manager recommended Silent Switcher® step-down regulators. However, they are expensive with limited availability and not easy to prototype due to BGA package.
We did LTspice simulations and discovered that Silent Switcher® step-down regulators are not as clean as claimed in the datasheet. We decided to use conventional LDO linear voltage regulators we are familiar with and selected those suitable for post SMPS use. Due to its size, it cannot plug in directly into ATX power connector like PicoPSU, so a PCB was designed and placed adjacent to motherboard’s ATX power connector.
We selected 2 industrial-grade Mean Well LRS series SMPS to feed regulated DC into the ATX Power Supply Board. Due to very high inrush current of 50A for LRS-100-5 and 65A for LRS-75-12, both specified for 230VAC, having a soft start PCB is mandatory. We use a fast-acting 2A circuit breaker / rocker switch and it has not tripped so far. Like our other music servers, fuse is not used.
AAMS S ATX Power Supply Board
The power supply board takes 12V and 5V from the LRS SMPS. They were adjusted to meet the minimum drop-out voltage required by the LDO voltage regulators. 3.3V is derived from 5V supply. There are 5 regulated voltages as specified below. It is capable of operating with all voltages at its maximum current, hence LRS-100-5 rated for 18A current was selected.
| Rail | Max Current |
|---|---|
| 5V Standby | 3A |
| 12V | 3A |
| 5V | 6A |
| 3.3V | 6A |
| 5V SSD | 3A (i.e. 2 SATA SSDs max) |
The ATX Power Supply PCB is placed adjacent to the motherboard so that only short run of Neotech SOCT DC cables is required into ATX power supply connector.
Other Components Installed Inside AAMS S
The picture below shows SSD tray and USB2 Isolator installed. Please note the empty space we plan to put 5V DC LPSU for USB2 Isolator. Using SMPS is not an option here.
The internal 5V DC power supply board is not ready yet, so for WAVE 2026, we will use an external 5V LPSU to power the USB2 Isolator via its DC jack.
Dimensions
Software Used
Like AAMS XT and AAMS XT LE, AAMS S uses Lyrion Music Server plus the 3 LMS plugins we developed, namely LMS Win Player, LMS UPnP Player, and CD Ripper. More information here.
Important Notice
This is preliminary product information, subject to change, as we continue to:
- finish the internal 5V DC LPSU board
- add EMI filter (still waiting for parts)
- tweak / fine tune other parameters and selection of components