I live in a city with the dirtiest power. lines are a mess! switching adapters everywhere. When making a linear power supply for a dac or a 2w amp, should I filter before and after the trafo? I have a load of old (discharged all caps already) power spplies with chokes and many ac, picofarad, yellow plastic caps, etc...
Any of that worth reusing?
Is it important to filter before the trafo as well as after?
Can I possibly clean this power without a ground terminal or will I need to use a waterpipe for ground?
Any designs for a power supply which could clean this power of 5v-12v without a working ground terminal on the plug?
landlords in this city do not wire the ground terminal on the plugs!
Should I just use batteries? (18650s)
I need 5v and 12v right now.
Thanks
Philip
"I'm gonna filter this dirty power and get rid of the NOISE somehow"
Any of that worth reusing?
Is it important to filter before the trafo as well as after?
Can I possibly clean this power without a ground terminal or will I need to use a waterpipe for ground?
Any designs for a power supply which could clean this power of 5v-12v without a working ground terminal on the plug?
landlords in this city do not wire the ground terminal on the plugs!
Should I just use batteries? (18650s)
I need 5v and 12v right now.
Thanks
Philip
"I'm gonna filter this dirty power and get rid of the NOISE somehow"
Last edited:
I do not know where you are, but if what you say is true, that you only have AC lines and no ground, and you have no recourse to your landlord, utility company, or local government, then nitpicking which regulator to use is the easiest part and not worth much time.
If it were me, I would be using some kind of 2 pronged power brick, something that gets you to low voltage AC or DC in a method that meets safety certifications. Once you have a brick in hand, figuring out any rectifiers, capacitors, regulators is easy.
If it were me, I would be using some kind of 2 pronged power brick, something that gets you to low voltage AC or DC in a method that meets safety certifications. Once you have a brick in hand, figuring out any rectifiers, capacitors, regulators is easy.
Ground is not a magic dumping 'ground' for noise etc.
If you have no ground then you will have to do the best approximation you can to Class II (double insulation) for safety. For audio you just need to remember that a voltage always exists between two points, and a current always flows in a loop. Ensure that currents flow where you want them to, and voltages are referenced to what they should be referenced to.
If you have no ground then you will have to do the best approximation you can to Class II (double insulation) for safety. For audio you just need to remember that a voltage always exists between two points, and a current always flows in a loop. Ensure that currents flow where you want them to, and voltages are referenced to what they should be referenced to.
I am specifically asking about filtering pre trafo and the benefits.
Electricity here is 50hz.
Are there any chokes that allow only 50hz to pass?
I have a step down which I may use but the transformer inside only has 3 taps.
How can that be possible and safe at the same time?
Would a step down provide additional smoothing or filtering from the harmonics present in the AC 220V power here?
How efficient/inefficient is it to run transformers in series?
Has anyone invented a transformer which produces multiphase power from single phase and rectifies the wave that way?
With a 3 secondary(+ V, 0, -V) tap, 2 primary tap trafo, is a diode bridge or a 2 diode setup preferred in hifi?
What new rectifier designs are practical and non switching?
The circuit is closed and just as it should be.
I have gone to additional lengths to insulate all live contacts.
When using record players for example, ground is very important and without it, hum is inevitable, from my experience.
Also, since a faraday cage must be grounded to actually work, it can be useful for minimizing interference leaked and picked up by the circuit
Electricity here is 50hz.
Are there any chokes that allow only 50hz to pass?
I have a step down which I may use but the transformer inside only has 3 taps.
How can that be possible and safe at the same time?
Would a step down provide additional smoothing or filtering from the harmonics present in the AC 220V power here?
How efficient/inefficient is it to run transformers in series?
Has anyone invented a transformer which produces multiphase power from single phase and rectifies the wave that way?
With a 3 secondary(+ V, 0, -V) tap, 2 primary tap trafo, is a diode bridge or a 2 diode setup preferred in hifi?
What new rectifier designs are practical and non switching?
The circuit is closed and just as it should be.
I have gone to additional lengths to insulate all live contacts.
When using record players for example, ground is very important and without it, hum is inevitable, from my experience.
Also, since a faraday cage must be grounded to actually work, it can be useful for minimizing interference leaked and picked up by the circuit
Last edited:
So batteries are the way to go?
Still no answers on my question about filtering pre trafo?
One thing I am sure about is that when I ground my devices, 95% of the noise disappears...
But I would like to be able to get clean power from the mains...
My other question was on using a step down.
"Phil' gonna filter the power right and isolate so its not the last thing he does but phil' gonna clean this dirty power if it's the last thing he does"
"he don't got no other choice"
Still no answers on my question about filtering pre trafo?
One thing I am sure about is that when I ground my devices, 95% of the noise disappears...
But I would like to be able to get clean power from the mains...
My other question was on using a step down.
"Phil' gonna filter the power right and isolate so its not the last thing he does but phil' gonna clean this dirty power if it's the last thing he does"
"he don't got no other choice"
No idea of your country but in the UK ALL mains outlet sockets MUST be three pin with an earth connection that conforms to British Standards and is safe.
Any rented property MUST conform or the Landlord/Lease Holder is held responsible.
If the mains supply is noisy, the Utility Company is liable to make good the supply.
The usual cause of noisy mains is overhead low voltage supply cables running from a transformer on a pole that is on the verge of overload.
There is no such thing as a single phase to three phase transformer.
Any rented property MUST conform or the Landlord/Lease Holder is held responsible.
If the mains supply is noisy, the Utility Company is liable to make good the supply.
The usual cause of noisy mains is overhead low voltage supply cables running from a transformer on a pole that is on the verge of overload.
There is no such thing as a single phase to three phase transformer.
Last edited:
In Thailand. You should see the power lines here! an absolute mess. Only CAT broadband even places ferrites on their cables. All others are sagging 30% of their height in the middle. Forget the matrix equations and calculating tension or thermal expansion they just throw the cables up and there is no space between the cables in the tangled mess hanging above pedestrians heads.
Average switching adapter here lasts 3 mos. tops.
I miss UK power. Got my Physics degree at QMUL.
NTM some old mullard valves from the lab professor.
Had a massive Beard and a garrard 301,
CD player was a Meridian 206.
Tannoy hpd 15", was one of the first to locate surrounds so got them cheap.
Nowadays I just use fullranges with the whizzer cones, which I trimmed to 2cm depth...
I am looking to do this all myself so no power cubes unless I build them.
A friend recommended car batteries but did not mention what to put in between them and my gear so how much of a friend he really was, I cannot say. 12.6V sounds innocuous until we start to multiply that by the current and figure the watts. I always put safety first. I am the type of guy who uses switches that disconnect the live and neutral wire along with multiple fuses.
To the answers above the previous one:
I also never thought ground was important until that Garrard 301 with the rewired rega arm. Then I learned that it may even be necessary to clean contacts on plugs to avoid diode formation which creates noise and picks up radio sometimes.
I know the basics of electricity, yes circuits should be circuits or they are not circuits
Not buying a power cube, came here bc I am building one!
--- Still looking for advice on pre trafo filtering and multiple trafos---
Also, would using an R-core provide significantly better filtering of the mains AC?
There is a new thread going on about Li-Po batteries on this site...
But I really do not want to use such an unstable, earth abusive solution.
"Phil gonna' do some cleaning. The electric type."
Average switching adapter here lasts 3 mos. tops.
I miss UK power. Got my Physics degree at QMUL.
NTM some old mullard valves from the lab professor.
Had a massive Beard and a garrard 301,
CD player was a Meridian 206.
Tannoy hpd 15", was one of the first to locate surrounds so got them cheap.
Nowadays I just use fullranges with the whizzer cones, which I trimmed to 2cm depth...
I am looking to do this all myself so no power cubes unless I build them.
A friend recommended car batteries but did not mention what to put in between them and my gear so how much of a friend he really was, I cannot say. 12.6V sounds innocuous until we start to multiply that by the current and figure the watts. I always put safety first. I am the type of guy who uses switches that disconnect the live and neutral wire along with multiple fuses.
To the answers above the previous one:
I also never thought ground was important until that Garrard 301 with the rewired rega arm. Then I learned that it may even be necessary to clean contacts on plugs to avoid diode formation which creates noise and picks up radio sometimes.
I know the basics of electricity, yes circuits should be circuits or they are not circuits
Not buying a power cube, came here bc I am building one!
--- Still looking for advice on pre trafo filtering and multiple trafos---
Also, would using an R-core provide significantly better filtering of the mains AC?
There is a new thread going on about Li-Po batteries on this site...
But I really do not want to use such an unstable, earth abusive solution.
"Phil gonna' do some cleaning. The electric type."
Last edited:
It´s hard to find a really clean earth connection. You can read an article: Interference-free Sound, in Elector 10/07 that deals with mains filtering.
A balanced power supply (AC) may be an alternative as well.
Balanced Power: The Next Generation
But please remember; dealing with high volatages is dangerous and you have to consider safety aspects over and over again.
A balanced power supply (AC) may be an alternative as well.
Balanced Power: The Next Generation
But please remember; dealing with high volatages is dangerous and you have to consider safety aspects over and over again.
Used a cheap line filter, grounded to chassis.
Standard EMI filter, about 1.5x the size of a 9v battery
The result, in my case,was miraclous, and filtering pre-trafo seems to be the thing to do here
90% of the buzzy hum was eliminated!
BTW... THE AMP>>>
Amp uses a 48v e and l trafo
feeding this rectifier unit
http://r.lnwfile.com/_/r/_raw/cy/gq/cf.jpg
and two M.O.S.F.E.T. drivers like these
http://3.bp.blogspot.com/-lv-De-ph31I/Trt3vpJ2A8I/AAAAAAAAAFs/lphX9qVSsLk/s1600/TR-7007A+MK6.jpg
Which are normally powering 3-10 2sa1941/2sc5220 pairs at the shops I have seen
I used one pair per channel, because I like the sound of less of them
bought three pair, tested on one channel, and then tested one pair, and I like that sound
My speakers are only 8" fullranges,
I have a superstition about points on the bottom of PCBs,
I file them off because They just seem like little antennas to me.
I believe those little points are the worst thing about PCBs given that they are printed or stamped with thick copper
I removed all blade connectors on the PCBs and soldered the connecting wires on.
Did not use the PCB the supplier had for the transistor pairs, wired those point to point.
Used some spare plywood to isolate the drivers from the chassis
Followed star grounding arrangement.
All is sounding excellent.
Chassis was recycled from a DIGI-002. Chassis in Thailand are relatively expensive!
Now I am moving on to building some ultralinear C-Core transformers for push-pull el84 monoblocks.
Picked up some cores NOS for so cheap,
Next question is whether to use one or two cores per O.T.
Going for 8K
Phil filtered the AC before the Trafo and he feels like he solved the noise problem!
Phil will always use small (not massive) EMI filters from now on!
Standard EMI filter, about 1.5x the size of a 9v battery
The result, in my case,was miraclous, and filtering pre-trafo seems to be the thing to do here
90% of the buzzy hum was eliminated!
BTW... THE AMP>>>
Amp uses a 48v e and l trafo
feeding this rectifier unit
http://r.lnwfile.com/_/r/_raw/cy/gq/cf.jpg
and two M.O.S.F.E.T. drivers like these
http://3.bp.blogspot.com/-lv-De-ph31I/Trt3vpJ2A8I/AAAAAAAAAFs/lphX9qVSsLk/s1600/TR-7007A+MK6.jpg
Which are normally powering 3-10 2sa1941/2sc5220 pairs at the shops I have seen
I used one pair per channel, because I like the sound of less of them
bought three pair, tested on one channel, and then tested one pair, and I like that sound
My speakers are only 8" fullranges,
I have a superstition about points on the bottom of PCBs,
I file them off because They just seem like little antennas to me.
I believe those little points are the worst thing about PCBs given that they are printed or stamped with thick copper
I removed all blade connectors on the PCBs and soldered the connecting wires on.
Did not use the PCB the supplier had for the transistor pairs, wired those point to point.
Used some spare plywood to isolate the drivers from the chassis
Followed star grounding arrangement.
All is sounding excellent.
Chassis was recycled from a DIGI-002. Chassis in Thailand are relatively expensive!
Now I am moving on to building some ultralinear C-Core transformers for push-pull el84 monoblocks.
Picked up some cores NOS for so cheap,
Next question is whether to use one or two cores per O.T.
Going for 8K
Phil filtered the AC before the Trafo and he feels like he solved the noise problem!
Phil will always use small (not massive) EMI filters from now on!
Last edited:
I am using a balanced trafo!
May still ground it, best I can find is a waterpipe.
A pot of fresh water also works, for about a day, for some reason, I found in a mad experiment in the past.
That was the dodgiest thing I ever tried in my life, but I had a room setup which kinda allowed me to ensure that pot was not going to get kicked onto the amp at the time
Ham radio enthusiasts make some interesting cleaners with ferrites BTW
Is your power 240-250V or 100-120V?
If it is a 100-120V the neutral wire is actually a ground already (not saying it is a good one though). In the US the ground wire is nothing more than a 3rd wire that connects to the neutral at the main panel. Codes require that earthing rods are installed at the main panel (and this is mostly so the utility company doesn't have to spend their money on their own bars at their transformer. There is a misconception that the ground wire is something magical. Not true. The fact of it being a 3rd wire connecting to the neutral only at the panel is only marginally better than using the neutral wire itself. That's because in rare faults if the house wiring is funky, the neutral can become a line wire. Having a 3rd wire as ground *could* help in that case.
That said, you can either use the neutral as ground (if you have a 100-120V at the wall) or (either 100-120V or 200-240V) you can install a local grounding rod and use it as a dedicated ground.
I don't believe the ground would be a solution to your problem, other than grounding the chassis, which would offer some EMI protection from the atmosphere but not HF protection from the dirty mains.
If it is a 100-120V the neutral wire is actually a ground already (not saying it is a good one though). In the US the ground wire is nothing more than a 3rd wire that connects to the neutral at the main panel. Codes require that earthing rods are installed at the main panel (and this is mostly so the utility company doesn't have to spend their money on their own bars at their transformer. There is a misconception that the ground wire is something magical. Not true. The fact of it being a 3rd wire connecting to the neutral only at the panel is only marginally better than using the neutral wire itself. That's because in rare faults if the house wiring is funky, the neutral can become a line wire. Having a 3rd wire as ground *could* help in that case.
That said, you can either use the neutral as ground (if you have a 100-120V at the wall) or (either 100-120V or 200-240V) you can install a local grounding rod and use it as a dedicated ground.
I don't believe the ground would be a solution to your problem, other than grounding the chassis, which would offer some EMI protection from the atmosphere but not HF protection from the dirty mains.
Interesting. That may give my old step down a new purpose in life! On another build, after the valve amp I am working on, I want to try something tiny.
EMI filter and a good chassis have made a great improvement.
Also rearranged the components so that the inputs and earlier sections with respect to the music source are far from the trafo, that may have helped too
Some of the best speakers I have ever heard were active.
They actually used 3 types of amps, each driver used its own amp
I am dreaming of copying that design right now
They were GEITHAIN. I will never forget those bad boys.
I imagine having internal monoblocks added weight to the speaker enclosures
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.