Grounding boxes ?

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pre65
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#1 Grounding boxes ?

Post by pre65 »

It seems that "grounding boxes" can lower the noise level on hi-fi components by using a high tech composite sandwich material to convert the unwanted noise into heat.

Given that they are reported to "work" can anyone guess as to how ?

An example here.

http://www.hifiplus.com/articles/stand-your-ground/
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Mike H
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#2 Re: Grounding boxes ?

Post by Mike H »

Reads like gibberish to me I'm afraid.
 
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#3 Re: Grounding boxes ?

Post by Nick »

No, I have no idea what they do. I have considered the idea (but never tried it) of a "active ground". Use a DC coupled power amp with its input referenced to earth with low pass filtering to give a clean ground referenced input, the use the output of the amp to provide the signal ground to the system. Would need some safety features adding to cope with it acting as a safety ground, but I am sure that can be done.
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#4 Re: Grounding boxes ?

Post by Nick »

Dave sells them, so I should try one sometime.
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#5 Re: Grounding boxes ?

Post by jack »

I believe these are similar to the
Entreq Tellus

The stuff inside looks very like Specular Haematite (also known as Specularite) grit - used in shot-blasting and elsewhere - plus some copper sheet & wire, a few brass strips and a couple of lumps of steel bar. All very crudely put together with a nice bit of wood cladding.

No-one seems to know how these things work, but haematite crystals used to be used in cats' whiskers radios as a detector, i.e. they form crude diodes at point junctions.

For around GBP 1,400... about GBP 10 worth of bits.

EDIT: Could be SiC (Carborundum) grit, which was much more common in Cats' Whiskers detectors and looks much the same as Speculite - SiC is also commonly used in rock tumblers for polishing stones and is really cheap - 15kg for about 20 quid, depending on how fine the grit is.
The brass strips in there (about 1cm x 10cm) seem to still have their thin plastic protective coating on!
Last edited by jack on Thu Oct 11, 2018 11:13 am, edited 4 times in total.
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The Stratmangler
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#6 Re: Grounding boxes ?

Post by The Stratmangler »

jack wrote: Thu Oct 11, 2018 9:30 am I believe these are similar to the
Entreq Tellus

The stuff inside looks very like Specular Haematite (also known as Specularite) grit - used in shot-blasting and elsewhere - plus some copper sheet & wire and a couple of lumps of steel bar. All very crudely put together with a nice bit of wood cladding.

No-one seems to know how these things work, but haematite crystals used to be used in cats' whiskers radios as a detector, i.e. they form crude diodes at point junctions.

For around GBP 1,400... about GBP 10 worth of bits.
Very interestink!
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#7 Re: Grounding boxes ?

Post by jack »

The puff on MCRU's site suggests that it just absorbs HF on the Earth or whatever. Not at all sure how it does this if there's no reference point, i.e. if it's just a box at the end of a bit of wire with no current flow, IMHO it whiffs of snake oil, otherwise it's basically an LPF.

https://mcru.co.uk/product/cad-gc1-grou ... 8a1a99f6c9

A clean Earth grounding system is surely the correct way to do this - it's pretty standard in electronics labs and for decent UPS systems and IT networks generally.

Note that such an earth connection cannot run parallel to other earthing systems and must be separate from any other earth, be it mesh or stake.

Here, because I have a 300KVA UPS, we have distinct earths for exactly this reason.

Some years ago, I installed a clean earth in my workshop:
WhatsApp Image 2018-06-26 at 18.53.56.jpeg
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#8 Re: Grounding boxes ?

Post by DSJR »

'Coherent' sells grounding boxes I believe and his friends on another forum have got into them, so I'm afraid that immediately put me off!

Is it better to have a separate ground plane for your stereo? Looking at some of the total foo for sale, I'm afraid I placed these things in with that, while making sure my mains cables are firmly connected and earthed properly where necessary - and not where needed to prevent hum loops...

Maybe I'm the ignorant one, but I've been through the brainwash shit decades ago and come out of it very suspicious to be honest...
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#9 Re: Grounding boxes ?

Post by Neal »

Are these boxes actually connected to a ‘ground’ though? I read the white paper on Dave’s site and it does read to me as gibberish as well. Also if there is a significant reduction in HF noise then it would be measurable but I see no claims for x dB amount of reduction.
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#10 Re: Grounding boxes ?

Post by The Stratmangler »

Where is it stated that a ground must physically be connected to anything?
It's just a circuit reference point.
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#11 Re: Grounding boxes ?

Post by Nick »

The Stratmangler wrote: Fri Oct 12, 2018 11:45 am Where is it stated that a ground must physically be connected to anything?
It's just a circuit reference point.
Yes, its necessary to separate how we think about the signal ground from the earth safety ground. They are not always the same thing. But in every case I can think of (other than one that is intentionally broken) they are connected together by a link of zero or more ohms (and with some given reactance) at least at one point.
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#12 Re: Grounding boxes ?

Post by mainscablesrus »

jack wrote: Thu Oct 11, 2018 9:30 am I believe these are similar to the
Entreq Tellus

The stuff inside looks very like Specular Haematite (also known as Specularite) grit - used in shot-blasting and elsewhere - plus some copper sheet & wire, a few brass strips and a couple of lumps of steel bar. All very crudely put together with a nice bit of wood cladding.

No-one seems to know how these things work, but haematite crystals used to be used in cats' whiskers radios as a detector, i.e. they form crude diodes at point junctions.

For around GBP 1,400... about GBP 10 worth of bits.

EDIT: Could be SiC (Carborundum) grit, which was much more common in Cats' Whiskers detectors and looks much the same as Speculite - SiC is also commonly used in rock tumblers for polishing stones and is really cheap - 15kg for about 20 quid, depending on how fine the grit is.
The brass strips in there (about 1cm x 10cm) seem to still have their thin plastic protective coating on!
Doubt it, if so make one for us all for a tenner I will have 1
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#13 Re: Grounding boxes ?

Post by mainscablesrus »

Neal wrote: Fri Oct 12, 2018 11:34 am Are these boxes actually connected to a ‘ground’ though? I read the white paper on Dave’s site and it does read to me as gibberish as well. Also if there is a significant reduction in HF noise then it would be measurable but I see no claims for x dB amount of reduction.
Buy one, plug it in and listen, if no difference return it. If it works well decide if the improvement is commensurate with monies paid, if so keep it if not send it back.

Oooops wrong forum, we don't spend thousands on foo here LOL!
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#14 Re: Grounding boxes ?

Post by Neal »

No we don’t for good fecking reason. What dB does it reduce the noise by?
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#15 Re: Grounding boxes ?

Post by jack »

mainscablesrus wrote: Fri Oct 12, 2018 10:07 pmDoubt it, if so make one for us all for a tenner I will have 1
Obviously my comments related to the Entreq Tellus, but there were only in10 quids worth of bits in there. Yes, your one has an acrylic case which I doubt affects the supposed performance of the unit, so perhaps I should have said "10 quids worth of potentially active bits'.

I made no comment as to what acoustic difference it may or may not make, just that the contents were somewhat underwhelming and, like it or not, would cost about 10 quid. The only thing that could change that estimate is if the grit is something truly exotic, but I think you know it isn't...

The puff goes on about noise on the mains earth, which can be a genuine issue, but that is easily solved with a clean earth

You make specific claims about changing noise into heat over a range of GHz. Just how much is the noise floor reduced, or are we just dealing with FUD and pseudo-science? If you make specific claims you should be prepared to defend them.

PS. Please don't just hide behind the "try it and see" weasel words - Neal asked a reasonable question; just how much is the noise floor reduced by? I'm also interested in how testing was done in the GHz region and how the noise floor was measured, i.e. referenced to what?

Saying that you have no idea is a perfectly good answer, but as has been said before, "extraordinary claims require extraordinary evidence'" (Carl Sagan).
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