SMPS PSU for Aleph

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I'm thinking the same thing (albeit 3 years later!)

For the last couple of years, I've been more than happy with my DIY Manger Audio speakers, home made CD-PRO2 spinner with Perpetual Technologies magic boxes! Unfortunately my (bought) tube amps are starting to fail. They make loud crackling and humming noises, so I want to go back to solid state.

Looking through my garage I have found a couple of unfinished projects. Two Aleph-X boards and two Tripath 1040A boards.

The question is which to go with? Either way, I'm looking at the coldamp products as a quick win for the power supply. My concern is the voltage: don't the Alephs need around 20-25V?

Gaz
 
I too looked a bit at SMPS some time ago and also found that 1. building one yourself is something for experts (critical pcb-layout and what not) 2. the ready available ones are not suitable for bridged amps as the output voltage is way too high.

In the end, if you look at the noise spectrum of an high end Infineon SMPS (see datasheet) it could happen you no longer want a SMPS - especially since the heat from the psu is neglible for any ClassA or high bias ClassAB-amp.

But you can certainly try that if you would like! No reason to be always reasonable :D

Have fun, Hannes
 
Hi there,

well, I have been thinking about using a SMPS for an audio power amp (Aleph 0S clone) too. Working now for approx. 19yrs in R&D for this power supply stuff I have gathered some know how about it. And yes, I see some advantages using this technology if properly done:
Better decoupling between the line and the amp`s supply lines due to reduced capacitive coupling (compared to a big toroid xformer), regulated output voltage and if you are using PFC decoupling gets even more superior due to the intermediate voltage which is regulated too (about 400 VDC in EU). Think of this when you are considering a line conditioner in order to decouple your equipment from the line...
EMI is always an issue with SMPS, but it`s the art to control it. In any case it is advantageous to use a post filter at the output to clean the DC lines.
Building an SMPS by your own is a whole lotta work and even more EMI testing and tweaking. I suggest like following if you intend to try a SMPS in your equipment:
Take an existing SMPS, i.e. favorably a DIN-Rail PSU which already has 24V (20 to 28V adjustment-range) output voltage. Take two of them (with proper wattage) in order to get the desired bipolar 20 - 25 VDC. Apply a post EMI filter at the output, both for DM and CM noise and see what you can get.
If I`ll find the time I`ll do so.
Regards, Jürgen
 
a post EMI filter at the output,

Now that's part of the problem: an IC-regulator has weak PSRR at high frequencies where most of the noise is. A choke is typically large and emits a magnetic field that may couple into the audio-path.

Anyway, it would be cool if one of the guys with expertise would share/do a proper design and also post pcb-artwork so that we all could give it a try :D It's a pity this has not happen yet.

Have fun, Hannes
 
RC-filter for output filtering??

In that case forget about output regulation - but maybe I misunderstood you?

I didn't say it cannot be done, it's merely a question of what performance you want. If it just should work with noise say at -60dB, SMPS will do. Considering all those die-hards with their single Farad-cap banks, signal-to-noise would need to be much better :D

Have fun, Hannes
 
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