Any advice warmly accepted...
Short story, my stereo power amp transformer needs to be moved from inside the amp casing to an external case. Bridges and smoothing caps are all on the main amp board so will stay where they are in the original power amp casing.
From the little I have read it is best to have transformers, bridges and smoothing caps all in the external box, but that is rather a huge project for me (beginner), I have already been 3 months or so with out any proper music!
So for now, just the transformer is moving out, I want to hear well presented music again soon
With the transformer in an external case, wired to the original amp casing:
1) Is there any thing like extra caps that should go in the transformer box?
2) I seem to be reading that snubber caps across the diodes is a good idea to help reduce the pulses on the cable from external box to amp casing?
Much appreciate any pointers or advice on anything else that I may well have overlooked, on this so thought simple project :-0
Many thanks
dc
Short story, my stereo power amp transformer needs to be moved from inside the amp casing to an external case. Bridges and smoothing caps are all on the main amp board so will stay where they are in the original power amp casing.
From the little I have read it is best to have transformers, bridges and smoothing caps all in the external box, but that is rather a huge project for me (beginner), I have already been 3 months or so with out any proper music!
So for now, just the transformer is moving out, I want to hear well presented music again soon
With the transformer in an external case, wired to the original amp casing:
1) Is there any thing like extra caps that should go in the transformer box?
2) I seem to be reading that snubber caps across the diodes is a good idea to help reduce the pulses on the cable from external box to amp casing?
Much appreciate any pointers or advice on anything else that I may well have overlooked, on this so thought simple project :-0
Many thanks
dc
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Hi Deaf Cat,
If you want to move only the transformer from your current amp casing and outside of this casing all you basically have to do is to move the transformer and connect the wires from the transformer TO the amp mains board exactly like they are connected today. You cannot add any extra caps to the new transformer case because the mains supply there is still AC (i.e. before the rectifier diodes) and it won't make any difference (actually will cause severe problems).
I would also suggest you twist the wires going to and from the transformer in the pairs that corresponds with the voltages used i.e. the 230 VAC is one twisted pair and any secondary windings are also individual twisted pairs. In this way you reduce the electromagnetic radiation from the wires.
You may use a snubber circuitry but I'm not quite sure what to suggest here so would rather avoid doing so. Maybe someone else here may give you advice on this.
Cheers,
Jesper
If you want to move only the transformer from your current amp casing and outside of this casing all you basically have to do is to move the transformer and connect the wires from the transformer TO the amp mains board exactly like they are connected today. You cannot add any extra caps to the new transformer case because the mains supply there is still AC (i.e. before the rectifier diodes) and it won't make any difference (actually will cause severe problems).
I would also suggest you twist the wires going to and from the transformer in the pairs that corresponds with the voltages used i.e. the 230 VAC is one twisted pair and any secondary windings are also individual twisted pairs. In this way you reduce the electromagnetic radiation from the wires.
You may use a snubber circuitry but I'm not quite sure what to suggest here so would rather avoid doing so. Maybe someone else here may give you advice on this.
Cheers,
Jesper
Good Morning Jesper,
Wonderful, initially I was thinking just move it out and lengthen the secondary wires, simple
(but then read about extra caps and other bits and bobs.. hence this posting to clarify)
Very good point about twisting pairs of wires, I had not thought of that, thank you.
I have read a little in to snubbering, and it looks rather tricky stuff for a beginner, and may require measuring equipment I do not own, I will however read some more, to see if I can manage it while the amp is in bits..
Many thanks for your reply
cheers
All the best for the new year!
Wonderful, initially I was thinking just move it out and lengthen the secondary wires, simple
(but then read about extra caps and other bits and bobs.. hence this posting to clarify)
Very good point about twisting pairs of wires, I had not thought of that, thank you.
I have read a little in to snubbering, and it looks rather tricky stuff for a beginner, and may require measuring equipment I do not own, I will however read some more, to see if I can manage it while the amp is in bits..
Many thanks for your reply
cheers
All the best for the new year!
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Don't.
There are at least two issues.
a.) Safety
b.) audio performance.
Safety, all mains powered equipment that does not meet the ClassII standard MUST have a PE connection PERMANENTLY attached to the CHASSIS.
Performance, the transformer sends pulses of current to the capacitor input filter you have after the bridge rectifier.
You MUST keep the pulsing currents out of your AUDIO CIRCUITS. Keeping the bridge rectifier and the main smoothing capacitors SEPARATED from the transformer will make this requirement extremely difficult to achieve.
There are at least two issues.
a.) Safety
b.) audio performance.
Safety, all mains powered equipment that does not meet the ClassII standard MUST have a PE connection PERMANENTLY attached to the CHASSIS.
Performance, the transformer sends pulses of current to the capacitor input filter you have after the bridge rectifier.
You MUST keep the pulsing currents out of your AUDIO CIRCUITS. Keeping the bridge rectifier and the main smoothing capacitors SEPARATED from the transformer will make this requirement extremely difficult to achieve.
Yes, you could certainly just put the xfmr into another metal chassis and use decent cable to run it to your amplifier chassis. Don't forget both cases/chassis will need to be grounded.
Referring to the post above, safety can be overcome, but audio performance is a different beast (unless the proximity of the transformer is interfering with the audio signal to the point of ruining your listening experience) and I'd defer to Andrew's wisdom any day of the year (even 2015)....
Referring to the post above, safety can be overcome, but audio performance is a different beast (unless the proximity of the transformer is interfering with the audio signal to the point of ruining your listening experience) and I'd defer to Andrew's wisdom any day of the year (even 2015)....
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Oh yes I like to have things safe with family and cats around, so yes, all chassis will be connected to earth as long as they are plugged in, and circuit boards and the like will be isolated from the chassis.
Okay this is the part that I need help understanding, the length of wire in the amplifier box, from the transformer to the cct board is approx 140mm, with the transformer removed, the wire will be approx 140mm to exit point of the amplifiers box, and maybe 400mm from the outside of the amp box to the new external transformer box.
How, what, when, where will the pulses of current get into the audio ccts? I don't see that an extra length of cable on the out side of an earthed chassis would affect the audio cct board on the inside..
Or is it that the extra length of cable magnifies the pulse affect somehow?
Interested to know, as can always plan to move the caps and diodes out at a later date.. :-0.
Ah, so the snubber would help with reducing the pulses?
Many Thanks, I look forward to any further pointers/comments
much appreciated
Cheers
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The transformer and it's wiring will have existing loops and the existing field, both emitting radiation into adjacent parts.
The manufacturer may have arranged that the fields from ALL these sources cancel.
If you move one set of fields, you may find that the fields created by the remaining loops do not cancel.
Tell us why you have come up with your proposal.
Maybe we can see a better solution to a problem that you have identified. What are your measurements?
The manufacturer may have arranged that the fields from ALL these sources cancel.
If you move one set of fields, you may find that the fields created by the remaining loops do not cancel.
Tell us why you have come up with your proposal.
Maybe we can see a better solution to a problem that you have identified. What are your measurements?
Ok, Cool, I now understand, thank you
(Maybe this will be phase 1 then, rather than 'the' project.)
From an untrained eye perspective, the original wires were just run from point A to point B seemingly no patten pretty much higgledepigeldy as far as I could see, no twisted pairs, no avoiding components on the cct board etc.
Longer story/explanation, as to what is going on..
I wanted to experiment swapping out some sanwha smoothing caps for some Epcos Sikorel just for fun, to see if there was a difference in sound repro, start a tricky (for me) diy project, practice soldering etc.
The only way I could see to fit the new caps in, as they are a bit bigger than the originals, was to remove the transformers and put the new caps in the gap created, project getting bigger some what fast - beginner diyer! (all these new things to look out for in a new subject)
So yes I am going to added even more loop area, from the board where the caps were, to the new location of caps..
Oh dear O dear
So ideally, transformer, diodes, caps should be in the external psu box with rectified dc ran to the original amp box, with more caps in the original amp box (for some reason?)
I would love to do this But, from what I can work out there are big + and - rails and a set of smaller + and - rails which complicates things for me somewhat as to where what how on the cct board would I tap into with the new external supplies..??
Rega don't let anyone have their cct diagrams :-(
Oh dear O dear
The other thing that makes no sense to me is having a ground from the cct board to the chassis, when the chassis is not earthed with the power lead. Unless this is the floating ground that the rails are referenced to, that is connected to earth (power lead) somewhere else in the stereo set up - so I can't earth the amplifiers chassis (power lead) for the worry of creating ground loops?
Thanks for reading!
Any further suggestions/comments very welcome.
Many thanks
dc
(Maybe this will be phase 1 then, rather than 'the' project.)
From an untrained eye perspective, the original wires were just run from point A to point B seemingly no patten pretty much higgledepigeldy as far as I could see, no twisted pairs, no avoiding components on the cct board etc.
Longer story/explanation, as to what is going on..
I wanted to experiment swapping out some sanwha smoothing caps for some Epcos Sikorel just for fun, to see if there was a difference in sound repro, start a tricky (for me) diy project, practice soldering etc.
The only way I could see to fit the new caps in, as they are a bit bigger than the originals, was to remove the transformers and put the new caps in the gap created, project getting bigger some what fast - beginner diyer! (all these new things to look out for in a new subject)
So yes I am going to added even more loop area, from the board where the caps were, to the new location of caps..
Oh dear O dear
So ideally, transformer, diodes, caps should be in the external psu box with rectified dc ran to the original amp box, with more caps in the original amp box (for some reason?)
I would love to do this But, from what I can work out there are big + and - rails and a set of smaller + and - rails which complicates things for me somewhat as to where what how on the cct board would I tap into with the new external supplies..??
Rega don't let anyone have their cct diagrams :-(
Oh dear O dear
The other thing that makes no sense to me is having a ground from the cct board to the chassis, when the chassis is not earthed with the power lead. Unless this is the floating ground that the rails are referenced to, that is connected to earth (power lead) somewhere else in the stereo set up - so I can't earth the amplifiers chassis (power lead) for the worry of creating ground loops?
Thanks for reading!
Any further suggestions/comments very welcome.
Many thanks
dc
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If you want to learn about audio DIY then the best way is to buy, build and debug a simple kit.
Fiddling around with an existing working unit in order to 'improve' it is surprisingly popular as an alternative, but predictably frustrating for all concerned. It is easy to make something sound different, but harder to make it actually sound better (in the sense that the output is even closer to the input). That is when the modified unit actually works after surgery, and doesn't hum/buzz/oscillate/burn.
Fiddling around with an existing working unit in order to 'improve' it is surprisingly popular as an alternative, but predictably frustrating for all concerned. It is easy to make something sound different, but harder to make it actually sound better (in the sense that the output is even closer to the input). That is when the modified unit actually works after surgery, and doesn't hum/buzz/oscillate/burn.
Oh so true!
My first project was to change the binding posts, visit to the hi fi repair man not long after. That was a good number of years ago, and now I have got tempted to play again.. Oh Dear!
So yes I would agree it is a great idea to start with a simple build your own kit, but, my was working amp I disassembled about two months ago, slowly slowly when time permits putting back together, & fingers crossed!!!
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