Two Box server with linear power supply

[nickquick]

Hi,

That is a very nice looking build.

 

I am a few years into developing a linear power setup pcbs upwards. Your linears look like Sigma 11 type units, is that right ?

 

If I might offer some thoughts based on experience here which 200,000uf is a LOT on the input of the HDPLEX. Here with a very similar design I am finding that as little as 15,000 after the bridge and 12,000uf after the linear supply feeding into the 400w hdplex is where the sweet spot lies (low esr caps in both locations). Too much capacitance and the  sound gets very solid / slow and dynamics and detail really suffer. Feeding the HDPLEX for good SQ seems to be as much about speed and transient response as it is about ripple performance.

 

The HDPLEX 400W IMHO is an amazing piece of kit, its hard to credit the level of performance available from it if its fed with a really well optimised linear supply. If you havn't already voiced the setup with different levels of capacitance I would at least give it one try tuning this can be  it can be night and day in terms of SQ.

 

Another point you might want to consider. I can see that your HDPLEX is a V2.0x but it may be worth checking exactly which version. HDPLEX recently bought out v2.01 of their 400W DC ATX. I was frankly shocked at the difference in sound quality compared to the earlier v2.00 and have been poking around at board level of  the units to work out what is driving the change to SQ. As the component cost of building such a nice linear supply is pretty high its probably a good investment of $95 to get the 2.01 version if you don't already have it.  

 

It will be nice to hear how it all works out for SQ.

 

 

[nickquick]

I looked again at the pictures of your supply in its chassis. 

 

For my comments on capacitance values to apply I had assumed that the HDPLEX was being supplied by one of the s11 modules or another linear supply circuit that is not visible.

 

If there is no linear regulation in line with the HDPLEX then the cap values are not going to apply well. What are you using to in the design to supply the HDPLEX ? 

 

 

[nickquick]

So the HDPLEX supply is LC filtered but not regulated ?

 

That would explain the large C reservoir, with the LC values I guess it will be about 3-5 mv ripple assuming something like a 3 amp average load. I have seen other designs taking this approach but not had chance to hear one as yet.

 

I think high processing power is the way to go for sound quality. It comes with issues for the PSU but worth the effort I think.

 

I have done some serious server builds on different PC architectures incorporating bespoke electronics. My advice a when you move to higher processing power is select mother board chipset very carefully. I see folks obsessed about CPUs models and thread counts then select a motherboard architecture almost at random. The CPU does count but the ultimate potential and foundation of a sever that can exceed the performance of the most expensive commercial servers is the right chipset selection. Iv spent way too much time reading Intel data sheets over and over :-)

 

The psu your building is very interesting, it will be good to hear how you get on particularly if the DC ATX is an unregulated LC supply.  

 

Keep us posted on how things sound :-)