Netgear GS108T Power Supply

[Spannko]

I think it’s fair to say that the GS108T with its supplied 12V power supply punches well above its weight and is the preferred switch combination round here.

As usual, my curiosity has got the better of me, so I’ve been investigating the possibility of improving the GS108T by substituting the power supply for something ‘better’. I’ve tried the iFi, which wasn’t a good combination, and recently the Friwo, which most people didn’t think worked quite as well as the supplied power supply.

Whilst ferreting in the garage, I came across an old transformer, capacitor and diode bridge. And naturally, I thought “Why don’t I build a power supply for the GS108?”. In no time, I’d knocked up a very basic power supply and fired it up. I expected sparks, but to my amazement, it worked - for five mins! It was overheating, so I needed to add a heat sink, and it’s worked fine since.

Here’s a couple of vids of the two power supplies, DIY first & Netgear second, together with a photo the DIY version.

https://www.dropbox.com/sh/kk8k72oz9f3 ... 3DmYa?dl=0

[Defender]

was often wrong the last times so
I am shy to give my opinion but I like the self made power supply better
if you change to ON MUR 120 that might improve it even more

[Spannko]

Thanks defender, what’s ON MUR 120?

[Defender]

Thanks defender, what’s ON MUR 120?

the diodes

[Spannko]

Excellent, thank you! I’ll get some ASAP.

EDIT: Argh! They’ve been discontinued!

[Ron The Mon]

Spannko,
It's not even close! That is a perfect "tune-dem" song. The stock supply allows much better following of the guitar notes as they rise and fall. Same goes for the bass line. With the DIY supply, the guitar and bass are out of tune with each other. Johnny's voice also has a jump of excitement in it with the stock supply.

I do like your heat sink solution with the tool and clamp; everyone has those. Very resourceful.

The solution to a better supply may be improving the stock supply itself. I have seen GS108 stock supplies used on eBay for a few dollars. Experimenting with that may be fruitful. If it is SMPS, shortening the DC cable and lengthening the AC may improve it. SMPS' usually sound better closer to the device. Improving components may help as well.

Ron The Mon

[Defender]

Ron has better ears than me rather follow his advice
@Ron thank you for pointing out where you think the difference is

[beck]

I am with Ron on this one.

[Charlie1]

+1 for normal. Seemed quite a lot better to me too.

[Ron The Mon]

Spannko,
There are many standards I've learned over the years. Many of them emanated from Julian Vereker. Some proven more-so by Fredrik Lejonklou.

1. A proper audio toroidal transformer has an iron core.

2. A proper audio transformer has a center-tapped output with single secondary outputs. It may have have multi-tapped primary's.

3. The center tapped lead is your central earth for your power supply.

4. All grounds must be connected to this earth point.

5. A transformer should be far from a low voltage audio circuit, but as close as possible.

6. A simple bridge rectifier sounds better than independent diodes.

I can go on but I'd advise improving minutely upon the stock power supply.

Ron The Mon

[Tendaberry]

I clearly prefer the standard power supply as well.

[Spannko]

Thanks everyone for your feedback. I totally agree that the Netgear PS is better than the DIY version. At the time of the recording, the DIY was quite irritating to listen to, whereas the Netgear just flows nicely. It’s been a couple of days since I put it together and it’s sounding much more acceptable now, but I haven’t compared it with the Netgear again yet.

Ron the Mon: Thanks for sharing your knowledge, it’s really helpful. I’m going to continue to experiment with the linear PS for now, only because my electronics knowledge is extremely limited: I can just about follow the manufacturer’s guides, so modifying high frequency circuits is well above my ability!

One thing that doesn’t really come over well in the vid’s is how much ‘nicer’ the linear supply sounds. The Netgear sounds like there’s a thin distortion veil over the music which is removed by the linear supply. I’m wondering if the difference between SMPS and LPS is a bit like the difference between mm and mc cartridges mc/smps are better than lps/mm, but more expensive to make well, so a cheaply made mc/smps doesn’t sound as good as a well made, but lower cost lps/mm? Just a thought.

EDIT: I’ve just done a quick comparison and although the DIYPS has improved, the Netgear smps is still more musical.

[ThomasOK]

Yes, I also found the Netgear PS more musical. The linear does some interesting things and tends to grab your attention but it isn't as in tune or in time as the Netgear one. Since you are in the UK it is probably difficult reversing the polarity but it definitely is more musical over here with the two prong plug connected one way vs. the other.

I think your analogy might be pretty good except the Netgear SMPS is obviously also a relatively cheap one - it just happens to also be pretty good. So it doesn't likely have to do with how cheap it is but how well it is designed. That is pretty applicable across the board, even if that good design might just be luck in some cases.

[sunbeamgls]

Would it have been more fun if the samples had not been labelled in advance of listening?

[Spannko]

With Mk1 being a miserable failure, let’s move on to Mk2.

https://www.dropbox.com/sh/de6wxwskigo ... MSyoa?dl=0

Enjoy!

[tokenbrit]

Enjoy!

Thanks. I did. Really close - Mk2 has a nice rhythmic drive that suits the song...

[beck]

Enjoy!

Thanks. I did. Really close - Mk2 has a nice rhythmic drive that suits the song...

+1

You can really hear what your PS is doing to the fulness of the sound.

And listening to your voice at the end you seem quite pleased with the result! :-)

[Spannko]

Enjoy!

Thanks. I did. Really close - Mk2 has a nice rhythmic drive that suits the song...

+1

You can really hear what your PS is doing to the fulness of the sound.

And listening to your voice at the end you seem quite pleased with the result! :-)

Ha ha! Yes, I did get a bit carried away :>)

The mk2 version does look promising, particularly since there’s a chance it’s not fully cooked yet, and there are other things I can try, such as a bridge rectifier (arriving soon), more/less capacitors, different capacitors, larger/smaller transformer, different regulators, layouts etc, etc!

[Spannko]

was often wrong the last times so
I am shy to give my opinion but I like the self made power supply better
if you change to ON MUR 120 that might improve it even more

I’ve discovered that OnSemi have released a lead free replacement for the MUR120 and they’re currently running in :o) Watch this space!

[Defender]

I have actually not heard those and as Ron recommended the integrated bridge rectifiers are better in his opinion (I really much trust his experience/ears). I have never compared individual diodes to integrated bridge rectifiers but I saw also Fredrik is using integrated ones so this is maybe the way to go.
But I am interested to know what the outcome is.

[linesrg]

Spannko,

I think you may need to try an ALWSR or Sjöström Audio based power supply?

Regards

Richard

[Spannko]

I have actually not heard those and as Ron recommended the integrated bridge rectifiers are better in his opinion (I really much trust his experience/ears). I have never compared individual diodes to integrated bridge rectifiers but I saw also Fredrik is using integrated ones so this is maybe the way to go.
But I am interested to know what the outcome is.

I’m discovering that generalisations are not too reliable. My favourite so far is a four diode affair, but have I heard the best bridge rectifier? I doubt it. Also, I’ve built a 4 diode rectifier which doesn’t sound great.

When they’ve run in a bit more, I’ll post some vids

[Spannko]

Spannko,

I think you may need to try an ALWSR or Sjöström Audio based power supply?

Regards

Richard

Thanks linesrg. I’m not familiar with the ALWSR or Sjöström. Have you heard them?

[beck]

Have you seen this Spannko:

https://www.lejonklou.com/forum/viewtop ... f=2&t=5075

[Spannko]

Have you seen this Spannko:

https://www.lejonklou.com/forum/viewtop ... f=2&t=5075

Thanks beck.