My supply had a much larger impact on the sound, but both are very nice pieces of gear. I borrowed the boulder supply from a friend of mine, one of the reasons I wanted to build one myself. If you need to deliver 110W with 50W lost in regulator I would pick at least 250W transformer. Current spikes from bridge/capacitors have much higher RMS value than average value heating copper (windings) while high frequency content is heating the core. Transformer is also a problem because 110 W supply requires almost twice rating because of the nature of load.
You can do much better with modern regulators. In addition LM338 has very poor ripple rejection equal 0dB (none) at 100kHz. This means 8.5V x 6A = 51W (big heatsink). I requires almost 3V input output differential making it total of 8.5V drop across regulator if you provide for +10/-20% line variation (3V +18.5Vx0.3). Fast switching brings more noise pollution.Īs for designing with LM338 - I did it over 20 years ago and would not do it again. "Ideally you would want the switching frequency to be so fast that it would be impossible to tell when it turned off and back on." - Only for efficiency sake. Older regulators like LM338 are sensitive to output capacitors' ESR - might start oscillating when ESR is too high but also oscillate when it is too low. They are also not as easy to design as it seems. Linear regulators are noisy, require huge transformers are most often unregulated. Modern switching power supplies are switching at zero voltage/zero current while linear power supply switches at max voltage.Īs I understand it you need about 6A for this supply while LM338 is rated only 5A (continuous). The lowest I know to operate is about 50kHz - non audible. Mintzar - I don't know of a single switching mode power supply that operates in audible band. Send me an email and I can potentially get you started. That means the regulator, resistors, capacitors, and diodes all have to be able to handle 6A of current (preferably something like 10-12A MINIMUM for safety). What I do is build a 22V PSU and regulate it down to 18v5. What I can tell you is that you need to build an 18v5 PSU capable of outputting 6A. The only tidbit of "plans" are the pinout for the iSense DC connector for the Mini. This is a design that I did the research for and constructed myself. The off periods are why switchmode supplies sound noisy and often mechanical.Īs for the Mac Mini PSU. Ideally you would want the switching frequency to be so fast that it would be impossible to tell when it turned off and back on. Switchmode supplies with a switching frequency in the audible spectrum have a moment where zero current flows, the lower the switching frequency the more noticeable those periods of off time become. If you start with an amplifier, but have a crappy source the signal can only be as good as the source. And if you build a better supply for your source you start with better. The power coming from the wall is the power used to create every signal in your audio system. Granted, most companies don't put expensive power supplies in their gear, it's just too expensive to manufacture for a large company. Companies like Bel Canto, W4S, Nuforce, etc all use switching supplies and are incredibly noisy and dry sounding. EVERY switchmode supply I have heard was noisy compared to a linear supply. The switching aspect is well above the audible spectrum. My amplifier is a Class D amplifier with a Linear PSU. All power issues will be resolved and done by the Sizcom mac mini service calicut team and also replaced within no time.Switchmode supplies in many products on the market DO NOT have their switching frequency above the audible spectrum, however. Mac Mini adapter comes with more peculiarities but faces common issues related to battery and power. If your device requires any replacement of parts, we select top-quality spare parts which are selected meticulously from the store. We are much acquainted with every kind of chip-level repairs and therefore you can get a faster fix for issues with your Mac mini from us. If you happen to experience sudden turning off or issues with turning on your Mac mini, then there might be some kind of issues with the power supply circuit inside the device. We are well-organized with well-versed technicians, who are provided with top-notch facilities to give you the finest services for Mac mini power Do you face power issues in your Mac mini? If you do, don’t worry perfect solutions are available at Sizcom Apple mac mini service center Calicut for all kinds of problems with the power supply board in your Mac mini.
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