Distance between components

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MarkWoody
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Distance between components

Unread post by MarkWoody »

What is the minimum distance you recommend between components to eliminate hum - especially with reference to A80 power amps, Phono 2 (& 2x PSU) and P90sa pre-amp?
Obviously the PSUs and Phono 2 have captive leads, so I realise that is non-negotiable as it were.

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karatestu
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Re: Distance between components

Unread post by karatestu »

I have done some experiments in the past with transformer placement. Not nva but with my diy stuff. All my stuff is laid out on two foot square sheets of 20mm chipboard and no shielding or cases. This has been just for experiments with layout and so i can get to stuff to do modifications.

I have found that the more distance you can give the better. Transformers have external hum fields horizontally and vertically. I would say that more distance is needed in the vertical plane as emi seems to be stronger through the toroids core. The bigger VA the transformer the bigger the stray field. Keep a bmu well away from anything as it has a big ass transformer :shhh: 1000VA ?

The doc does not recommend racks and for good reason. Transformers placed in close proximity above or below sensitive circuitry such as phono amp etc is not good. A big coffee table would be better with phono power supplies as far away from the head unit as possible.

If you must use a rack get one with as big a distance between shelves as possible. I have built a prototype rack out of fence posts with provision to change shelf positions. Shelves are 60 x 60cm and i use as much of the space as possible to keep things distanced. I have my shelves 35cm apart with all the transformers above each other and away from other circuitry.

I found that even when there was no audible hum to start with, moving the transformer further away brought musical benefits. This was especially the case with regulators.

Bottom line is distance is your friend but the doc will know the minimum you can get away with.

Stu
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Dr Bunsen Honeydew
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Re: Distance between components

Unread post by Dr Bunsen Honeydew »

As above - very good reply.

Geoff.R.G
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Re: Distance between components

Unread post by Geoff.R.G »

Dr Bunsen Honeydew wrote: Sat Nov 25, 2017 9:16 am As above - very good reply.
Like all good science, based on observation.

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karatestu
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Re: Distance between components

Unread post by karatestu »

Geoff.R.G wrote: Sat Nov 25, 2017 12:42 pm
Dr Bunsen Honeydew wrote: Sat Nov 25, 2017 9:16 am As above - very good reply.
Like all good science, based on observation.
The only way to do it :grin:

As i did not have any transformers, rectifiers, capacitor banks or regulators fixed down i could move them around at will. I left the transformer lead outs long (i specified 30cm lead out wires) so that i could get the transformer as far away from other stuff as possible. All transformers at the front of the chipboard sheets, mains wiring along one side and well away from anything else.

I remember even moving the transformers around whilst music was still playing. That way i could hear the effects in real time as opposed to stopping the music, moving the transformer and then playing music again. It was an valuable lesson. Also having no cases is a good thing.

I have all amplifier circuits, voltage regulators, volume pot and selector switch at the rear of the 60cm x 60cm sheets so that signal wiring is as short as possible and away from anything that might cause loss of musicality. I use 6mm wooden dowel to extend the pot and switch shafts to the front where i have the control knobs.There is some leeway with locating rectifiers and capacitor banks. I have them somewhere between the transformers at the front and the rest of the stuff at the back. I find rectifiers and caps are not really affected by emi and having the transformer to rectifier to capacitor charging loop as small as possible really helps .

Regulators should be as close to the circuits they are powering as possible but not too close with some of the super regulators as oscillation can sometimes rear its ugly head if things are not thought through properly.

I am really happy with the way i have things laid out at the moment and will eventually build a wooden cabinet (music centre) with a removable front panel to get in for servicing and tweaking.

Sorry a bit off topic and a bit over the top, its just my experiments were very fruitful. :grin:
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Hemmo1969
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Re: Distance between components

Unread post by Hemmo1969 »

karatestu wrote: Sat Nov 25, 2017 1:14 pm
Geoff.R.G wrote: Sat Nov 25, 2017 12:42 pm
Dr Bunsen Honeydew wrote: Sat Nov 25, 2017 9:16 am As above - very good reply.
Like all good science, based on observation.
The only way to do it :grin:

As i did not have any transformers, rectifiers, capacitor banks or regulators fixed down i could move them around at will. I left the transformer lead outs long (i specified 30cm lead out wires) so that i could get the transformer as far away from other stuff as possible. All transformers at the front of the chipboard sheets, mains wiring along one side and well away from anything else.

I remember even moving the transformers around whilst music was still playing. That way i could hear the effects in real time as opposed to stopping the music, moving the transformer and then playing music again. It was an valuable lesson. Also having no cases is a good thing.

I have all amplifier circuits, voltage regulators, volume pot and selector switch at the rear of the 60cm x 60cm sheets so that signal wiring is as short as possible and away from anything that might cause loss of musicality. I use 6mm wooden dowel to extend the pot and switch shafts to the front where i have the control knobs.There is some leeway with locating rectifiers and capacitor banks. I have them somewhere between the transformers at the front and the rest of the stuff at the back. I find rectifiers and caps are not really affected by emi and having the transformer to rectifier to capacitor charging loop as small as possible really helps .

Regulators should be as close to the circuits they are powering as possible but not too close with some of the super regulators as oscillation can sometimes rear its ugly head if things are not thought through properly.

I am really happy with the way i have things laid out at the moment and will eventually build a wooden cabinet (music centre) with a removable front panel to get in for servicing and tweaking.

Sorry a bit off topic and a bit over the top, its just my experiments were very fruitful. :grin:
30cm ? Doesn’t seam that long TBH

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Dr Bunsen Honeydew
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Re: Distance between components

Unread post by Dr Bunsen Honeydew »

Mate, you know more about what makes a good amplifier than over 90% of so called proper manufacturers.

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karatestu
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Re: Distance between components

Unread post by karatestu »

One of the reasons i was attracted here and like it so much is because your views and designs echo most of the things i have learned myself by experimenting. I could not design an amplifier circuit or regulator from scratch but building and putting different bits of the puzzle together and trying different things is where i get my kicks.

I think i must have got the transformer lead out lengths wrong - it was a while ago. I do have enough length to point the transformer lead outs forwards away from the other circuitry, round the perimeter of the transformer and still have 20cm between the edge of the transformer and the rectifier and caps. My transformers have over sized cores, electrostatic shield and goss band but still the bloody emi gets out, especially where the lead out wires exit the transformer.

Other things i find good are hard wiring mains cables, hardwiring signal and dc power cables at one end, soldering where possible instead of crimps etc and generally removing as many un-needed connections as possible. Wiring is another thing i have messed about with - best rout from one thing to another, wire diameter, dielectric etc etc. Fasinating stuff.
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Re: Distance between components

Unread post by Geoff.R.G »

The problems with manufactured items are, amongst other things:
The need to be visually appealing, both for domestic harmony and to attract buyers*.
The need for compact boxes and, with professional amps, the requirement to fit in 19" racks.
The requirement to be compliant with legislation, meaning they go for metal cases and IEC connectors where there are better ways.
Material constraints, wood might not be a manufacturers first choice.
Ease of manufacture, generally by machine which often results in less than optimal component spacing because there needs to be clearance at the edges of the case/base.
Finally that most important consideration, cost of production which results in the smallest possible case with the shortest possible wire lengths and the most compact PCB that will contain the circuit.

Built it your self and pretty much anything is possible.
*Quite where this leaves many valve amps is another matter entirely.

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Dr Bunsen Honeydew
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Re: Distance between components

Unread post by Dr Bunsen Honeydew »

"The requirement to be compliant with legislation, meaning they go for metal cases and IEC connectors where there are better ways."

This sentence is just plain wrong.

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