More mains musings....Eliminating hum from speakers and improvements going forward.

[Gazjam]

Been looking again at my mains setup...

Since the introduction of new 300B valves, new interconnects and a new Dac I’ve been getting a bit of buzz through my balanced mains transformer?
Not a problem in itself as the unit is in the next room, BUT its been leaking hum into the system and through the speakers.
Not good.

So tightened up all earth connections and fitted a DC blocker in circuit which mostly cured it, but not completely.
So if its not just DC on the mains, must be an earth loop somewhere?
Tidied up all the cables behind the rack but no cigar.
Took any switching supplies for routers whatever and powered them from a Belkin isolating mains block in the other room.
Still hum.

Process of elimination, aside swapping interconnects around I did this for all my main boxes
variables were:

- Powering directly from the hardwired balanced mains IEC lead
- Powering straight from the wall using a kettle lead
- Powering from balanced mains connected double socket using kettle lead.

Long story short,
Turns out the new 300Bs was causing it when I directly powered the amp from the balanced mains.
Weirdly, connecting it via a double socket I’d hooked up to it and hum was gone.

*EDIT* Less of a problem now the valves have ran in a bit, maybe initially drifting out of spec until they bedded in - still hums a bit so still an issue.

So powering amp with seperate mains cable plugged in to the double socket is the way to go.
HERES THE QUESTION PART:

As both my Dac and Valve amp will be plugged into the double socket, I want to run a half metre of *best quality* mains cable from the balanced mains to the double socket.
Using a switchless MK or Crabtree socket at the moment, and want to fit something better in there.

1) Whats the best quality mains cable I can buy (only a half metre so cost not a factor)
2) Without being too Foo about it, whats a recommended double 13a socket?

I use PS Audio mains cables for amp and Dac, everything else hardwired from balanced mains so no need to go back to the joy of trying out different mains cables thankfully.

Just a half meter of top banana mains cable and a quality double 13a socket.
The fench solid core stuff Marco got me thats hooking up my balanced mains is great and perfect for that application, just want to maximise the power supply to dac and the amp now I’ve seen that last bit of cable before the black box DOES make a difference.


Thanks much. :)

[Blueflash]

The best cable I have come across is:https://www.fscables.com/products/lf-329-screened-colour-coded.html?filter_set[]=40,44

The best sockets are the Furutech twin socket which will allow you to have a cable for each socket and will take 10mm cable if you divide the cable between the cable clamp screw.

Just another thought, have you got a centre tapped transformer in your balanced mains setup ? I make sure that the centre tap is connected to the mains earth and is the same thickness as the two balanced output wires.

It will firmly clamp the centre tap to 0v and will make sure your RCCB has the 0v earth to reference any fault conditions.

[Gazjam]

Thanks Alex.
What others did you try and in what application?

Thinking the Furutech FP-S55N might be a main contender...

[CageyH]

I want to run a half metre of *best quality* mains cable from the balanced mains to the double socket.

Have a look at the Neotech NEP-3001 III or NEP-3003 III cables. They are pretty good.

[Blueflash]

I have tried the 16mm T&E cable, some armoured cable and LoRad.

I am using whatever gives me the best shielding as I am surrounded by Wifi points on my estate. I used to be OK having a 16mm T&E cable going into a balanced mains transformer but noticed harsher treble and soundstage width reduction over time.

It took me a while to sort the problem until I started doing tests on the Dac and found there was 5Ghz attached to power supplies and the analogue outputs.

Also there was 2.5mV 5Ghz signal being picked up by just leaving the scope probes unconnected and resting on the workbench !!!

I have not finished with the setup yet. I need the shielding from my meter onwards which I will do later in the year but converting all my cables to 2.5mm LoRad silver plated has restored the sound quality, but does need 1/2 hour warmup time before coming on song.

The cable you have suggested should be OK, but I need the 100% shielding here which is why I was pleased to find FS Cables.

[Marco]

Hi Gaz,

I've got the perfect solution, mate. I have spare, probably just under 1m, of PCOCC-A Furukawa/Oyaide mains cable, as shown here:https://tm3connections.com//index.php?_route_=oyaide-eefs2-cable, which I use on all my mains leads, and indeed forms the base cable for the MCRU 'Ultimate' mains lead, shown here: https://mcru.co.uk/product/the-ultimate-fig8-mains-lead/?v=79cba1185463

You could of course, if necessary, cut it down to 0.5m.

This is genuine top-notch mains cable, Gaz, and due to its construction (if you read the blurb) pretty much unbeatable in the application you're intending. The cable I have is also fitted with a Rhodium version of one of these Furutech 13A plugs :https://mcru.co.uk/product/furutech-fi-1363-g-gold-plated-mains-plug/?v=79cba1185463

The other end of the cable, however, has bare wires and would need an IEC plug fitted. However, if you want it the cable 'as is' with the Furutech 13A plug, I could do it for very good price (mates rates). Just PM me if you're interested :cool:

In terms of quality double sockets, I'd got for one of these, as I've used them before and they're superb, not stupidly priced either: https://www.ebay.co.uk/itm/Silver-Plated-UK-Double-Wall-Socket-Unswitched/331399831027?_trkparms=aid%3D555018%26algo%3DPL.SI M%26ao%3D2%26asc%3D43782%26meid%3Dd833f8db858e4e02 8142ba145402e825%26pid%3D100005%26rk%3D1%26rkt%3D6 %26mehot%3Dag%26sd%3D231550206726%26itm%3D33139983 1027&_trksid=p2047675.c100005.m1851

If you want maximum SPPV, that's where it's at. They're the 'audiophile wall socket' equivalent of the Monoprice HDMI cables!;)

Marco.

[Gazjam]

Great reply Alex, thanks.

Interesting your using a balanced mains unit similar to myself.
What gauge of FS cable did you use?

Thinking 6mm x 2 is the sweetspot?

[Gazjam]

Thanks Kev,
I’ll take a look.

[Gazjam]

Hi Gaz,

I've got the perfect solution, mate. I have spare, probably just under 1m, of PCOCC-A Furukawa/Oyaide mains cable, as shown here:https://tm3connections.com//index.php?_route_=oyaide-eefs2-cable, which I use on all my mains leads, and indeed forms the base cable for the MCRU 'Ultimate' mains lead, shown here: https://mcru.co.uk/product/the-ultimate-fig8-mains-lead/?v=79cba1185463

You could of course, if necessary, cut it down to 0.5m.

This is genuine top-notch mains cable, Gaz, and due to its construction (if you read the blurb) pretty much unbeatable in the application you're intending. The cable I have is also fitted with a Rhodium version of one of these Furutech 13A plugs :https://mcru.co.uk/product/furutech-fi-1363-g-gold-plated-mains-plug/?v=79cba1185463

The other end of the cable, however, has bare wires and would need an IEC plug fitted. However, if you want it the cable 'as is' with the Furutech 13A plug, I could do it for very good price (mates rates). Just PM me if you're interested :cool:

In terms of quality double sockets, I'd got for one of these, as I've used them before and they're superb, not stupidly priced either: https://www.ebay.co.uk/itm/Silver-Plated-UK-Double-Wall-Socket-Unswitched/331399831027?_trkparms=aid%3D555018%26algo%3DPL.SI M%26ao%3D2%26asc%3D43782%26meid%3Dd833f8db858e4e02 8142ba145402e825%26pid%3D100005%26rk%3D1%26rkt%3D6 %26mehot%3Dag%26sd%3D231550206726%26itm%3D33139983 1027&_trksid=p2047675.c100005.m1851

If you want maximum SPPV, that's where it's at. They're the 'audiophile wall socket' equivalent of the Monoprice HDMI cables!;)

Marco.

Thanks Marco,
you have PM mate.

[Marco]

Replied to :cool:

Marco.

[CageyH]

Marco,

[Off topic] You tried those cables yet? ;) [/Off topic]

Gaz, the Neotech is also OCC, although stranded, and mates up nicely with OCC plugs. ;)

[Gazjam]

Will have a play with a couple of options, promised myself I wouldnt though lol

Second thoughts...I’ll try Marcos option and probably call it quits.
Assuming it’ll sound more than good enough.

[wee tee cee]

Strange you mentioning hum Gary ive noticed my BMU a tad noisy of late.

Weather/temperature increased load on the mains due to the proper winter we have been having?

I thought maybe my current set up was maybe taxing my 1500 bmu but your post is a bit too much of a coincidence.

Is the hum coming through the tweeter?

[Marco]

Marco,

[Off topic] You tried those cables yet? ;) [/Off topic]


Lol. no not yet. Got it pencilled in for tomorrow though, as I'll be in all day and have plenty of time to assess things :cool:

Marco.

[Marco]

Second thoughts...I’ll try Marcos option and probably call it quits.
Assuming it’ll sound more than good enough.

I think it'll hit the spot nicely, and predict you'll get a very worthwhile overall improvement :)

Marco.

[Gazjam]

Thanks matey :thumbsup:

[Gazjam]

Strange you mentioning hum Gary ive noticed my BMU a tad noisy of late.

Weather/temperature increased load on the mains due to the proper winter we have been having?

I thought maybe my current set up was maybe taxing my 1500 bmu but your post is a bit too much of a coincidence.

Is the hum coming through the tweeter?

Hadnt thought of that Tony, weirder in my case as Ive fitted a DC Blocker between mains and my BMU.
Coming thru the woofers I think, turned the tweeters L-Pad right down, cutting off the tweeter, and hum was present.
Its a 50hz hum so woofer driven.

[Blueflash]

Great reply Alex, thanks.

Interesting your using a balanced mains unit similar to myself.
What gauge of FS cable did you use?

Thinking 6mm x 2 is the sweetspot?

I have got a bit mental with the cables. I have 16mm going into an industrial 32A switch to power the BMU and 2 off 10mm going into the Furutech double socket.

Later in the year I will be running 25mm cable into the dedicated CU instead of the 10mm T&E which is feeding it at present. I am copying the setup that is used in the Astoria recording studio as designed by Philip Newall.

[Mike Reed]

I have got a bit mental with the cables. I have 16mm going into an industrial 32A switch to power the BMU and 2 off 10mm going into the Furutech double socket.

Later in the year I will be running 25mm cable into the dedicated CU instead of the 10mm T&E which is feeding it at present. I am copying the setup that is used in the Astoria recording studio as designed by Philip Newall.

How come you've got two T&E cables going into one double socket? I don't know the Furutech, but why would it have two sets of inputs ?

Can I assume you're replacing your 10mm2 T&E feeding your c.u. with tails? This is the normal installation procedure from either the meter or the junction box, surely. 10mm2 would be used for your radials (which I think you do). I have tails to my c.u. (with individual RCBOs) and 10 as well as 6 mm2 radials to (effectively)my kit.

I'm not familiar with balanced mains (nor really understand it), and don't use any mains regeneration units, though a local chap with pretty classy kit put one in, onto his one h/d radial and hasn't looked back.

[Blueflash]

How come you've got two T&E cables going into one double socket? I don't know the Furutech, but why would it have two sets of inputs ?

Can I assume you're replacing your 10mm2 T&E feeding your c.u. with tails? This is the normal installation procedure from either the meter or the junction box, surely. 10mm2 would be used for your radials (which I think you do). I have tails to my c.u. (with individual RCBOs) and 10 as well as 6 mm2 radials to (effectively)my kit.

I'm not familiar with balanced mains (nor really understand it), and don't use any mains regeneration units, though a local chap with pretty classy kit put one in, onto his one h/d radial and hasn't looked back.

The Furutech double socket is two separate sockets on one face plate so instead of using jumper wires from one socket to the other, I am using one 10mm LF-329 cable for each socket.

I will be replacing the 10mm cable with LF-329 25mm cable which is very well screened so hopefully will render my setup immune to the effects of RFI.

With the balanced mains transformer, it gets rid of any DC or RFI on the mains supply so it will sound the same even during peak usage times.

I do not have to wait until after 9-00 pm to get the best listening experience.