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Gram Amp2 power supply

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martynyesfan View Drop Down
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    Posted: 25 Sep 2016 at 5:44pm
Hi All - very pleased with the sound of my Gram amp 2 which I've had for a few months now. Reading through the installation instructions I can see that an unfiltered supply should be used - as I'm in possession of a T----a mains filter please could someone tell me why it's best not to use it! I'm assuming it's ok to use it to power the amp?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 25 Sep 2016 at 8:27pm
Signal Return Currents:
Kirchoff's Law tells us that at any point in a circuit the algebraic sum of the currents is zero. This tells us that all currents flow in circles and, particularly, that the return current must always be considered when analyzing a circuit...

Where does current come from?

Power station ultimately, although most current in a circuit returns to a low impedance source in its power supply if "stiff" enough. However, some returns further back, which might be a transformer secondary. Further back than that will be a local substation - it's obviously flowing from there so it must return to it (along with all the other current everything else on the block is using of course - but those few micro-amps don't evaporate).

Filters (usually) place inductors in both line and neutral meaning return current has to negotiate the neutral inductor, and that's not "stiff" at all frequencies a modern circuit operates at (although far beyond the audible spectrum). Mind you, there are HF losses in power wiring, but not as much as an intentional inductor.

Therefore it is no surprise that a circuit having a closure frequency up in the low MHz (high gain circuits such as phono stages) sometimes sound different when used with and without mains filters.

Some bright spark might say "well, the HF decoupling must be crap in such a circuit" to which I reply they all are due to parasitics. It's just that after all my years I take nothing for granted. And so the capacitors in a mains filter won't go very high in frequency either.

You know, its one of those things some people hear and others don't. We heard it and thought it worth mentioning. Some will and do think we're stupid making such comments but I don't give a hang...

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ernie Quote  Post ReplyReply Direct Link To This Post Posted: 25 Sep 2016 at 10:02pm
Originally posted by Graham Slee Graham Slee wrote:

Signal Return Currents:
Kirchoff's Law tells us that at any point in a circuit the algebraic sum of the currents is zero. This tells us that all currents flow in circles and, particularly, that the return current must always be considered when analyzing a circuit...

Where does current come from?

Power station ultimately, although most current in a circuit returns to a low impedance source in its power supply if "stiff" enough. However, some returns further back, which might be a transformer secondary. Further back than that will be a local substation - it's obviously flowing from there so it must return to it (along with all the other current everything else on the block is using of course - but those few micro-amps don't evaporate).

Filters (usually) place inductors in both line and neutral meaning return current has to negotiate the neutral inductor, and that's not "stiff" at all frequencies a modern circuit operates at (although far beyond the audible spectrum). Mind you, there are HF losses in power wiring, but not as much as an intentional inductor.

Therefore it is no surprise that a circuit having a closure frequency up in the low MHz (high gain circuits such as phono stages) sometimes sound different when used with and without mains filters.

Some bright spark might say "well, the HF decoupling must be crap in such a circuit" to which I reply they all are due to parasitics. It's just that after all my years I take nothing for granted. And so the capacitors in a mains filter won't go very high in frequency either.

You know, its one of those things some people hear and others don't. We heard it and thought it worth mentioning. Some will and do think we're stupid making such comments but I don't give a hang...

It's not Beltism.



Hi Graham, as you suggest leaving GSP kit "always on", is it wise to protect it some how? There are a miriad of devices out there some even reported to make your Hifi sound better (I'm an disbeliever btw). Should some kind of surge protection be used or is it a waste of time? I mean from a protection point of view.

I've a Majestic, Proprii, Era V set up (always powered) and I do wonder if I should have some surge protection. If yes any suggestions?
There are 10 kinds of people. Those who understand binary and those who don't.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 26 Sep 2016 at 9:14am
A mains surge arrester is a good idea if you can get one without a filter.

A quick search found this:
http://www.viking-direct.co.uk/catalog/catalogSku.do?id=6978168

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Post Options Post Options   Thanks (0) Thanks(0)   Quote martynyesfan Quote  Post ReplyReply Direct Link To This Post Posted: 26 Sep 2016 at 10:30am
Graham - many thanks for the quick response even if some of it was over my head! I took notice of the phono stage's instructions when I first installed it and avoided plugging it in to the filter. Cheers, Martyn
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Post Options Post Options   Thanks (0) Thanks(0)   Quote pcourtney Quote  Post ReplyReply Direct Link To This Post Posted: 26 Sep 2016 at 11:53pm
would the 4 way be OK as well Graham 

http://www.viking-direct.co.uk/catalog/catalogSku.do?id=6978186

I can't see anywhere on those product sheets where it says if it has filters or not  :-(
GS Accession MM Pre, Red Wine Audio Signature 30.2 Amp and AKG K-1000 headphones
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Graham Slee Quote  Post ReplyReply Direct Link To This Post Posted: 27 Sep 2016 at 8:46am
It appears to be simply a surge arrester.
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