Power Supplies/Source Placement

I second the request for someone knowledgeable to explain this.

Thanks,

Chris

Ade,

My friend John Channing (hello John) has got a PhD in this sort of stuff, but my basic explanation is that The 52 has to deal with low level signals which are more easily corrupted by magnetic fields, whereas the poweramps have higher level signals so maybe less corrupted.

But the 300 has the bits separated from the amp bit and it sounds a bit better than the 250mk2?

I don't realy know. I am not an expert at all.

regards

Dev

I too would like to hear the logic of various placement combinations for a single rack.

There has been quite a lot of comments here about transformer hum in the reference series.
I have a 250 and a SC and can confirm the transformer hum which understandably increases as the mains get "dirtier" like when the washing machine is running.

The 250 is the main culprit because it is drawing significant current to drive the speakers whereas the SC I assume is really just ticking over to supply my 282.

I am about to get an XPS2 for my CDX2 which effectively turns the CDX2 into a transformer less box so now I will have 2 "clean" components handling sensitive signals in close proximity to 3 components with merrily humming transformers. I would like to do the best I can with the placement order and my own logic suggests to me the 250 should be furtherest away from the 282 & CDX2 and that there is probably slightly more current called for in the XPS2 than the SC so that comes next and finally the SC sits above the XPS2, under the 282 with the CDX2 on top.

This is not the way recommended by NAIM to Ade

regards from a slightly puzzled
GEOFF

Don't confuse mechanical noise (buzzing) with the electrical fields generated by the transformers.

Generally the simple advice is get all items containing transformer as far as practical from non-transformer containing items.

The transformer has an electromagnetic field around it (mainly magnetic) and this will couple into the low-level stages of the other electronics and cause audible degradation.

Some items are worse than other - the Prefix, or MC stage is far more sensitive than a line level preamp, for example.

How you then organise within these rules comes down to personal preference and specific space limitiations.

Andy.

Andy

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The transformer has an electromagnetic field around it (mainly magnetic) and this will couple into the low-level stages of the other electronics and cause audible degradation.

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My understanding of transformers is rudimentary

I always thought that toroids have almost no radiated field?

I`m in the process of re-installing my racking and this is one of the main issues i`m grappling with.

initial tests I have performed show an audible change caused by increasing sereration up to six inches from powered boxes, so it would appear that toroids DO produce significant radiated field

Given: (1) all the powered boxes in my system(Scap, 2x 135s, NAPST, Hicap for Prefix) CDP )and(2) the (small) interconnect lengths, siting all the kit optimally is turning into a nightmare...any advice would be welcome

laurie S

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Originally posted by Laurie Saunders:
Andy

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The transformer has an electromagnetic field around it (mainly magnetic) and this will couple into the low-level stages of the other electronics and cause audible degradation.

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My understanding of transformers is rudimentary

I always thought that toroids have almost no radiated field?

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Laurie,

Do a search on John Channing and toroid on this forum there is a picture of the type of field & strength produced from a x-former.

Dev

thanks

Laurie S

Laurie,

A toroidal has an EM field that can be as much as 90% or less of that from a more conventional frame transformer.

But it's still there, and easily measurable - IIRC you have a Prefix, just wave your Hicap close to it and listen with nothing playing, you'll hear the hum. An MC stage has very high gain as it is amplifying signals at tiny levels, as a consequence tiny EM fields in the vicinity can have an effect.

The field strength falls off with the square of the distance, therefore small changes can make a surprising difference, e.g. doubling the distance reduces the field by 4 times, trebling it reduces it by a factor of 9 times.

Inverse Square Law

Toroidal Stray Fields

Andy.

P.S. Note the minima on the fields shown on the Nuvotem site and how the Naim transformers are generally positioned within the boxes.

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IIRC you have a Prefix, just wave your Hicap close to it and listen with nothing playing, you'll hear the hum

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thanks Andy

Visualizing waving a Hicap near my prefix brings a smile!

I`m familiar with the Inverse Square law..what I really want to find out is how far apart do powered boxes (eg 135s, Scap need to be away from EACH OTHER to eliminate(is this possible?) interaction

Please don`t say "as far as the leads will allow"....Realistically anything much over 6 inches apart is going to be problematic

cheers

laurie s

Andrew

Thanks for the input. I went to the "toroidal" link and I see a significant reduction in field area is claimed by the use of select materials and carefull design.
I wonder how far Naim goes in that direction? Do you konw if for example they use "Mu-Metal" fixing bolts?

Also excuse my ignorance but does the field area change signifcantly as current demand is increased as in a power amp?

It also perhaps highlights the other issue which is that with Naim you intentionally pipe the audio signals into the power supply box which is bringing them into proximity with the field of the transformer.Does'nt this negate the argument that you should keep the sensitive signal box (282 etc) further away from the powered boxes?

regards
GEOFF

Laurie,

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Please don`t say "as far as the leads will allow"....Realistically anything much over 6 inches apart is going to be problematic

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I guess "as far as you can manage" is then the best advice

The items to be most concerned about, within the limitations you have, are items without transformers.

Therefore Prefix and preamp need to be as far as you can practically manage from transformer-containing items. I'd personally take the view that transformer-containing items could be very close together, possibly even stacked, if this helps increase the distance to the other items. I don't need to tell you about using your ears though, so that's the best advice, it's just a bloody pain moving stuff around!

I couldn't possibly state categorically what is the min distance before the items stop interacting, but I guess the length of the SNAIC's will give you a clue as to Naim's view of the matter...

Geoff,

I don't know what attention Naim give to addressing the field generated by the transformer. In any audio design there's a balance, sometimes improving one aspect (i.e. reducing the transformer field) can have detrimental effects sonically. Naim do not usee GOSS bands, for example, they generally mount the transformers using non-magntic hardware though.

I'm sure there are changes in the field, dependant upon load, but I doubt that it's too significant - it's one of those things that due to simple physics is easier to cure by physical placement, although this obviously isn't an option to everyone, due to domestic constraints.

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It also perhaps highlights the other issue which is that with Naim you intentionally pipe the audio signals into the power supply box which is bringing them into proximity with the field of the transformer.Does'nt this negate the argument that you should keep the sensitive signal box (282 etc) further away from the powered boxes?

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The effect that this will have on the signal is dependant upon many factors. The signal connections internal to the PSU are short and since the frequency of the field is low (50 / 60Hz) the signal connections appear electrically very short and as a consequence, the amount of pickup is negligible.

In addition the impedance of the signal wiring is relatively low, this further reduces the amount of signal pickup and finally the orientation of the wiring, relative to the transformer, has an effect.

Naim obviously feel that the benefits of this approach outweigh the possible detrimental effects.

Andy.

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I'd personally take the view that transformer-containing items could be very close together, possibly even stacked, if this helps increase the distance to the other items. I don't need to tell you about using your ears though, so that's the best advice, it's just a bloody pain moving stuff around!

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I`ve recently experimented with increasing the distance between POWERED boxes(135s, scap, hicap, NAPST)....the changes were marked


I would agree...it is a pain moving the stuff around.....Scaps are wrist-sprainingly heavy

regards

laurie S

I still don't understand why I was advised to place the piece of equipment with the largest transformer (250) directly under the most sensitive equipment, as I assume a larger transformer has a bigger effect.

Ade

Laurie,

You said the changes were marked when increasing the distance between *caps and power amps.

Can you explain what kind of improvements you found ?

Thanks,

Claus

Claus

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Can you explain what kind of improvements you found ?

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I`ll try.

Essentially the sond became cleaner, with better(percieved) seperation....less"muddy" (relatively) speaking and a slight reduction in "glassines"

This is a difficult area, as its hard to isolate a single cause/effect and I`m still working on it!

I`ll let you know in a couple of month`s time..


laurie S

Thanks Laurie.

Further info later on would be nice.

I have my 250 sitting on top of my Supercap, as close as can get!

No more shelves in the rack but I guess I could put the 250 somewhere else (on the floor or under a TV) if the difference would be significant.

Does anyone know if it's safe to run the 250 turned 90 degrees (standing on right or left side)??

Claus

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I have my 250 sitting on top of my Supercap, as close as can get

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whatever else..you could try sliding a sheet of, say, mdf, between the two to see(hear) if it makes any difference

I predict that it would

laurie S

... yes, I'll try a sheet of MDF in between the boxes.

Problem is that the distance from the upper box to the shelf above is only a few cm.

I would have liked the spacing between the shelves to be smaller. I can just manage to put 2 Naim boxes on each level, but 250 & Supercap are the only ones I stack. One more shelf and the same total height would have been really nice....

Anyway, will try a very thin MDF sheet one of these days.

Thanks

Claus

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Problem is that the distance from the upper box to the shelf above is only a few cm.

I would have liked the spacing between the shelves to be smaller. I can just manage to put 2 Naim boxes on each level, but 250 & Supercap are the only ones I stack. One more shelf and the same total height would have been really nice....

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I know the problem...this is why I am completely re-instating my (wall) shelf setup......the task is daunting ......I need at least 11 shelves!

Laurie S