Netgear GS108T Power Supply

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andy2
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Re: Netgear GS108T Power Supply

Post by andy2 » 2020-05-07 07:37

Hi Spannko,

It’s been a looooong time since I dabbled in electronics *, but are you sure that the diode bridge in your schematic is drawn correctly?

You probably have a very good reason, or a conceptual idea, as to why the circuit is as stripped down as it is, but have you tried stripping it down even more by decreasing the amount of caps to lower the internal impedance of the circuit?

*
http://bitsavers.trailing-edge.com/comp ... rcuits.pdf

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Re: Netgear GS108T Power Supply

Post by Spannko » 2020-05-07 10:07

Thanks for your input andy2, and thanks for the link to the book - it’s a real gem 🤓

I’ve had a quick look at the book, but couldn’t find anything related to the circuits internal impedance. Would you mind explaining a bit more about that, and why you think it would help? I must stress that I’m an absolute beginner and my knowledge of electronics is seriously limited!

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Re: Netgear GS108T Power Supply

Post by andy2 » 2020-05-07 12:42

Being new here I dunno if I’m comfortable handing out advice on stuff where I’m light years behind Fredrik on his forum.. plus I also don’t know if he wants the forum to be about diy audio projects.
That said in general terms the perfectly stable constant voltage power supply should have 0 output impedance.
It should also be very low noise and in this particular application I would assume that HF noise is particularly important.
The parallel caps in your design are there to smoothen out the sawtooth ripple output from the diode bridge. Every cap adds impedance. Once that job is done I would not think there is really any need for a lot of capacitive storage on the unregulated side of the supply in this case since the load of the device serviced by the PS should be pretty stable.

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Re: Netgear GS108T Power Supply

Post by Spannko » 2020-05-07 13:50

I think we’re ok andy2. This area of the forum is set aside for diy projects, amongst other stuff.

Just as a matter of interest, have you ever built your own power supply and listened to the result? The reason I ask is because at this point in my “power supply designer” career 😂 it’s not clear how much design theory relates to tune playing ability.

Re the caps: I’ve used 1000uF caps so I can experiment with total cap value which I could convert into one cap at a later date. I believe there are advantages and disadvantages of paralleled caps, but tbh, I’m focusing on how the total combination plays music. I also appreciate that 99.9% of electronics engineers will read this and think I’ve taken leave of my senses 😂😂😂

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Re: Netgear GS108T Power Supply

Post by V.A.MKD » 2020-05-07 15:34

If voltage is OK, why don't you try without Voltage Regulator ...
Music First ...
Vlado

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Re: Netgear GS108T Power Supply

Post by andy2 » 2020-05-07 16:43

Sure, well over thirty years ago I used to build tube pre and power-amps.

We regulated the living daylight out of every stage in those things and evaluated again and again and again..
Then I ran into Ivor and Charlie Brennan at CES in Chicago; we danced the night away in their hotel room to music played on Isobarik speakers w Naim amplification. Never had so much fun listening to recorded music before.

Arriving back home I chucked my Golmund turntable and huge exotic speakers along with the amps and got the Lp12/Ittok/Asak I had tucked away in kitchen cabinet back into operation; got me a Naim 32/250 combo and a pair of Kans, hooked everything up to the Lp12 and never looked back😀

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Re: Netgear GS108T Power Supply

Post by Spannko » 2020-05-07 17:33

V.A.MKD wrote:
2020-05-07 15:34
If voltage is OK, why don't you try without Voltage Regulator ...
The voltage off the caps is about 20V, which is too high for the GS108T. It’s worth trying in the future though, with a lower voltage output transformer.

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Re: Netgear GS108T Power Supply

Post by Spannko » 2020-05-07 17:35

andy2 wrote:
2020-05-07 16:43
Sure, well over thirty years ago I used to build tube pre and power-amps.

We regulated the living daylight out of every stage in those things and evaluated again and again and again..
Then I ran into Ivor and Charlie Brennan at CES in Chicago; we danced the night away in their hotel room to music played on Isobarik speakers w Naim amplification. Never had so much fun listening to recorded music before.

Arriving back home I chucked my Golmund turntable and huge exotic speakers along with the amps and got the Lp12/Ittok/Asak I had tucked away in kitchen cabinet back into operation; got me a Naim 32/250 combo and a pair of Kans, hooked everything up to the Lp12 and never looked back😀
Does that mean your diy designs were less musical than the Naims?

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Re: Netgear GS108T Power Supply

Post by andy2 » 2020-05-07 18:55

Yes, in a big way. 😳

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Re: Netgear GS108T Power Supply

Post by Spannko » 2020-05-08 02:56

In that case, as long as I stay away from the text books, I should be fine! 😁

Seriously though, I’m finding that none of the text books mention anything related to designing for musicality, so it’s totally seat of the pants stuff!

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Re: Netgear GS108T Power Supply

Post by beck » 2020-05-08 10:44

Spannko wrote:
2020-05-08 02:56
In that case, as long as I stay away from the text books, I should be fine! 😁

Seriously though, I’m finding that none of the text books mention anything related to designing for musicality, so it’s totally seat of the pants stuff!
That is exactly how I feel when experimenting with setup! :-)

Both your clips are enjoyable Spannko but different from each other.

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Re: Netgear GS108T Power Supply

Post by Spannko » 2020-05-08 11:24

Thanks beck. Out of the two, I think the Netgear is the more musical by a slight margin, and the DIY has a better sound in that it is clearer, more open and spacious, but when the music gets more complex, the illusion starts to break down a bit. It’s OK’ish, but still not quite good enough.

The old Antrim transformer didn’t display that quality, whereas all of the new transformers I’ve bought have, so I’m hoping that when I get the transformer sorted out there’ll be a big step up in performance 🤞.

Trans-Tronic have quoted me £130 for a custom transformer, built to my own spec. It’s a crazy price, but if I don’t try it, I’ll never know how much difference a transformer can really make.

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Re: Netgear GS108T Power Supply

Post by beck » 2020-05-08 19:03

Spannko wrote:
2020-05-08 11:24

Trans-Tronic have quoted me £130 for a custom transformer, built to my own spec. It’s a crazy price, but if I don’t try it, I’ll never know how much difference a transformer can really make.
Nothing ventured, nothing gained! :-)

I keep getting better and better music from my cd player (because I do not give up). Cd is a fantastic medium for music IF they had just taken into account that you have to be able to trim the vibrations to perfection effecting the cd players internal laser and electronic boards!

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Re: Netgear GS108T Power Supply

Post by Spannko » 2020-05-09 11:25

beck wrote:
2020-05-08 19:03
I keep getting better and better music from my cd player (because I do not give up). Cd is a fantastic medium for music IF they had just taken into account that you have to be able to trim the vibrations to perfection effecting the cd players internal laser and electronic boards!
I totally agree beck. Networked audio is probably more about convenience, fashion and being “new”, in order to attract the masses. It certainly wasn’t conceived to advance the art of music transportation.

CD players suffer from all the vibrations and moving parts, as you say, but they’re also designed as a closed circuit, which I’m sure is a good thing. Ethernet is too open, in that the streamer designer has no control over the incoming signal. The data component of the signal is robust, but the carrier is more like the “Wild West” . It’s a free for all, with any amount of crap allowed through on the carrier, just as long as it doesn’t affect the data, which because it’s so robust, can be at levels high enough to get through the streamers defences, affect the DAC and modulate the PS.

This is why we’re seeing a proliferation of “audiophile” network switches and home made power supplies 😁

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Re: Netgear GS108T Power Supply

Post by Spannko » 2020-05-21 00:08

On to Mk9 we go!

The new transformer arrived today. It’s the red one in the photo below.
5BEAD9B4-916F-4FB0-91C5-881BA762CF50.jpeg
5BEAD9B4-916F-4FB0-91C5-881BA762CF50.jpeg (2.21 MiB) Viewed 158 times
A comparison with the Netgear PS can be found here:

https://www.dropbox.com/sh/xaktibhjvbj ... kJn_a?dl=0

Enjoy!

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Re: Netgear GS108T Power Supply

Post by Charlie1 » 2020-05-21 00:23

Wow, this is tough. You have a great sounding PSU there.

Tbh, either is very good and the system sounds very musical.

I think yours is slightly more musical. It has a gentler sound though so hope you're not missing too much impact.

Keep going, you're doing a great job.

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Re: Netgear GS108T Power Supply

Post by beck » 2020-05-21 08:41

👍

Well done Spannko. I forget the hifi and enjoy the music with your DIY. :-)

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Re: Netgear GS108T Power Supply

Post by Spannko » 2020-05-21 16:32

Thanks guys.

Here’s another comparison, especially for the Tuneista’s

https://www.dropbox.com/sh/7af9e21crrm ... PkWSa?dl=0

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