Bas Horneman said:
That would probably be the ideal, with each well sized for the device it's powering. But I'd just try one for your digital stuff, and one for analogue, as big as you can get or afford. A great place for iso transformers is a metal recycler, where large units can be picked up cheap. If I had a basement where I could put them, I'd have no problem having a multi-kVA trans for each component, because the ones I've sourced from recyclers in the past have been very modest in outlay, but physically large and ugly industrial items. I also bought a 2.4kVA toroid off ebay that was surplus from a manufacturer of medical gear. It came with multiple 240V secondaries, dual primaries and an ES sheild for about $US20. He'd thrown others away before this because he couldn't sell them!. Hunt around, you might be able to find something cheap.
Years back we measured some large EI core iso trans for frequency response (noise) on a specan because of a noise problem we couldn't quite get rid of in an industrial area with VERY dirty mains, and the ones we bought dropped off quite steeply above 1kHz or so.
I've noticed things sound better at night, too. But I don't think it's RF noise, or even really audio. Up until 23.00, the mains voltage jumps around all over the place, but after midnight, it's far more stable. Thus, all our AC heaters are constantly having their temperature changed slightly and do not reach a stable equilibrium, similarly for unstabilized HTs.
An isolation transformer with E/S would be a very good start for getting rid of the RF hash. They're not expensive, so a 500VA or even 2kVA wouldn't be ridiculous. Because the mains often has a DC component (which saturates cores easily), a bigger transformer would be better. Unless, you have one specially made, and ask for a gapped core to prevent saturation due to DC.
However, an isolation transformer won't do anything that a properly designed mains transformer in the equipment should do. It's penny-pinching that hardly any modern kit has an E/S screen on its mains transformer.
An isolation transformer with E/S would be a very good start for getting rid of the RF hash. They're not expensive, so a 500VA or even 2kVA wouldn't be ridiculous. Because the mains often has a DC component (which saturates cores easily), a bigger transformer would be better. Unless, you have one specially made, and ask for a gapped core to prevent saturation due to DC.
However, an isolation transformer won't do anything that a properly designed mains transformer in the equipment should do. It's penny-pinching that hardly any modern kit has an E/S screen on its mains transformer.
Luckily DIY'ers don't have such a problem...All my transformers torroïdal or EI have such a screen
Wouldn't they give you an extra 40dB reduction in capacitive coupling of noise?
That said spec's aren't everything. I'll just wait till I strike the jackpot with some or other lottery before I kit out my house with Isolation transformers all round. Then again I might just get a moderate one and see what it does..There is no substitute for experience.
Regards,
Bas
Hi Tim;
>>>...I highly doubt it's line noise...<<<
No offence intended, but the difference between better line isolation on my CD player was "night and day", literally. And it's not like I had a big investment one way or the other (thus no psychological imperative that "I paid a gazillion $$ on this thing so it BETTER work") - the first isofilter I tossed together was just a pair of RS 25.2VCT trafos and some AC rated caps - all of which were on a breadboard and all of which were 'recyclable'.
In that same vein, the addition of a 90 cent "X2" 250VAC rated, UL Listed AC mains filtering cap to the mains in of my 2A3 yielded an instant improvement in the sound. Again, if it's not line AC noise, I'm darned if I know why.
Hi Bas;
>>>...I'll just wait till I strike the jackpot with some or other lottery before I kit out my house with Isolation transformers all round. Then again I might just get a moderate one and see what it does...<<<
I'd love to read the results of that experiment! Just wish I could afford to try it over here!!
All the best,
Morse
>>>...I highly doubt it's line noise...<<<
No offence intended, but the difference between better line isolation on my CD player was "night and day", literally. And it's not like I had a big investment one way or the other (thus no psychological imperative that "I paid a gazillion $$ on this thing so it BETTER work") - the first isofilter I tossed together was just a pair of RS 25.2VCT trafos and some AC rated caps - all of which were on a breadboard and all of which were 'recyclable'.
In that same vein, the addition of a 90 cent "X2" 250VAC rated, UL Listed AC mains filtering cap to the mains in of my 2A3 yielded an instant improvement in the sound. Again, if it's not line AC noise, I'm darned if I know why.
Hi Bas;
>>>...I'll just wait till I strike the jackpot with some or other lottery before I kit out my house with Isolation transformers all round. Then again I might just get a moderate one and see what it does...<<<
I'd love to read the results of that experiment! Just wish I could afford to try it over here!!
All the best,
Morse
mrothacher says:
#1... OK. I agree to an extent. I once plugged my TV into a computer grade line filter. Picture seemed better. But... with capacitance in the power transformer (TVs nowadays use direct connected AC, no step down/up transformer), and 1.5H and up choke, and 20-100µF capacitance.... it is difficult for 60 or 120 Hz to get through, let alone the kilo to megahertz frequencies. I would argue that one. But it is possible.
#2... I agree moreso. During the day there is much disturbance in the force... uh... much noise around from cars and planes (I live about 5 miles from a private airport) and birds and neighbors. At night it is much quieter. Has the "feel" in the ears like being up in the mountains (Blue Ridge/Appalachains to be exact. Not too high up, just very quiet). Very quiet.
#3... very interesting. I did not know this.
Thanks for the input so far folks!
Gabe
#1... OK. I agree to an extent. I once plugged my TV into a computer grade line filter. Picture seemed better. But... with capacitance in the power transformer (TVs nowadays use direct connected AC, no step down/up transformer), and 1.5H and up choke, and 20-100µF capacitance.... it is difficult for 60 or 120 Hz to get through, let alone the kilo to megahertz frequencies. I would argue that one. But it is possible.
#2... I agree moreso. During the day there is much disturbance in the force... uh... much noise around from cars and planes (I live about 5 miles from a private airport) and birds and neighbors. At night it is much quieter. Has the "feel" in the ears like being up in the mountains (Blue Ridge/Appalachains to be exact. Not too high up, just very quiet). Very quiet.
#3... very interesting. I did not know this.
Thanks for the input so far folks!
Gabe
CORNER CUTTING...
Hi,
This is oh so true....it seems that a lot of manufacturers try to save money by cutting corners in the wrong places.
For us. DIY or on demand maunfacturers
, knowing how to specify a good transformer or having a good xformer manufacturer who actually knows his stuff can be crucial to the endresult.
For my own projects I always have them custom made and I've never regretted this approach one minute.
Benefits are:
-absulotely dead quiet.
-no excessive heat.
-good regulation.
-good isolation from the mains.
There is more to a good PSU than just that but it's a darn good place to start.
Cheers,
P.S. Fellow member Nania started a thread on powerxformers for audio about a month ago, have a look if you like.
Hi,
This is oh so true....it seems that a lot of manufacturers try to save money by cutting corners in the wrong places.
For us. DIY or on demand maunfacturers
, knowing how to specify a good transformer or having a good xformer manufacturer who actually knows his stuff can be crucial to the endresult.For my own projects I always have them custom made and I've never regretted this approach one minute.
Benefits are:
-absulotely dead quiet.
-no excessive heat.
-good regulation.
-good isolation from the mains.
There is more to a good PSU than just that but it's a darn good place to start.
Cheers,
P.S. Fellow member Nania started a thread on powerxformers for audio about a month ago, have a look if you like.
Ive seen it stated here that our audio acuity becomes better at night. Is the assertion that this is because it is night, or because we are subject to less noise allowing the acuity to grow.
Would 20 minutes in an NC-10 anechoic chamber have the same effect on our hearing?
If this is the case it would argue well for listening environments with greater outside noise isolation. NC-10 would be a bit too extreme. It would also argue well for preconditioning ourselves before critical listening.
Would 20 minutes in an NC-10 anechoic chamber have the same effect on our hearing?
If this is the case it would argue well for listening environments with greater outside noise isolation. NC-10 would be a bit too extreme. It would also argue well for preconditioning ourselves before critical listening.
Re: Middle of the night bloom
Koinichiwa,
It is simple.
Ever since I started to use circuits that keep DC out of my Mains Transformers and PSU circuits that really isolate from mains born noise, I have found the sound of the system to be VERY consistent. There may still be a slight variation with time of day, but in general, my magic hours have increased to about 24 out of 24 Hours....
Sayonara
Koinichiwa,
Gabevee said:
It is simple.
Ever since I started to use circuits that keep DC out of my Mains Transformers and PSU circuits that really isolate from mains born noise, I have found the sound of the system to be VERY consistent. There may still be a slight variation with time of day, but in general, my magic hours have increased to about 24 out of 24 Hours....
Sayonara
Ambient noise is definitely a fairly big deal. I think the average noise level in a typical home is 40-50 dB during the day and 10dB or so lower at night, so some of those spacial cues, overtones, and other "bloomy stuff" may seem 10dB louder at night.
As far as acuity at night goes, I read about this effect sometime ago and I'll try to dig up a reference. It seems that humans have very poor night vision (especially when compared to animals that might want to eat humans) and it is thought that our sense of hearing may pick up some of the slack at night to warn us of approaching predators, crying babies and the like.
Sense deprivation is another trick of the mind. Try wearing ear plugs for an hour or so, then take them out and listen to music the result may surprise you. Depriving yourself of the sense for a little while can give you the (psychological?) impression that you have "Super Ears" I'm not sure if the the effect is purely psychological or physiological. I'll try running an audiogram on myself sometime and see if there's anything to it.
I also agree with the comment about power line noise vs. powerline stability.
I think powerline stability is much better after business hours and better still in the wee hours. I have a Kil-A-Watt (mentioned by Nelson Pass in another forum here) power meter plugged into an outlet in my listening room at all times and my powerline swings by tens of volts throughout the day. So, powerline stability probably has a bigger impact than the noise contribution.
Beer is also pretty good.
As far as acuity at night goes, I read about this effect sometime ago and I'll try to dig up a reference. It seems that humans have very poor night vision (especially when compared to animals that might want to eat humans) and it is thought that our sense of hearing may pick up some of the slack at night to warn us of approaching predators, crying babies and the like.
Sense deprivation is another trick of the mind. Try wearing ear plugs for an hour or so, then take them out and listen to music the result may surprise you. Depriving yourself of the sense for a little while can give you the (psychological?) impression that you have "Super Ears" I'm not sure if the the effect is purely psychological or physiological. I'll try running an audiogram on myself sometime and see if there's anything to it.
I also agree with the comment about power line noise vs. powerline stability.
I think powerline stability is much better after business hours and better still in the wee hours. I have a Kil-A-Watt (mentioned by Nelson Pass in another forum here) power meter plugged into an outlet in my listening room at all times and my powerline swings by tens of volts throughout the day. So, powerline stability probably has a bigger impact than the noise contribution.
Beer is also pretty good.
I believe that there is a physiological effect attached to acuity. My understanding is that there are muscles associated with the bone structure of the middle ear that effect energy transfers to the cochlea form the basilar membrane.
There should be both sensory and chemical cues that affect these muscles. Loud noises would obviously be a cue to decrease transfer and protect the cochlea. Caffeine has long been associated with tinnitus.
There should be both sensory and chemical cues that affect these muscles. Loud noises would obviously be a cue to decrease transfer and protect the cochlea. Caffeine has long been associated with tinnitus.
I don't see much difference in power line noise and stability between night and day chez moi, but I live in a bedroom community; the biggest local industry is probably NHT. The IS a big difference in ambient noise (2 year old Jimi asleep is much quieter than 2 year old Jimi awake), and a big difference in my hypothalamic response. Serotonin levels can affect subjective experience.
Either that or it's the random phase noise from photons in the daytime hitting my speakers and cables, screwing up subtle timing cues in the music. Or something. The bong hits can't have anything to do with it.
Either that or it's the random phase noise from photons in the daytime hitting my speakers and cables, screwing up subtle timing cues in the music. Or something. The bong hits can't have anything to do with it.
Konnichiwa Kuei Yang Wang
>>>...Ever since I started to use circuits that keep DC out of my Mains Transformers and PSU circuits...<<<
Could you suggest a schematic for a DC blocker that has proven to be effective? I'd like to try building something like that here.
Doumo arigatou gozaimasu for any assistance.
Morse
>>>...Ever since I started to use circuits that keep DC out of my Mains Transformers and PSU circuits...<<<
Could you suggest a schematic for a DC blocker that has proven to be effective? I'd like to try building something like that here.
Doumo arigatou gozaimasu for any assistance.
Morse
Blocking Dc.
Hi,
Indeed that does make a huge difference.
Some ways I know of to go about it:
- An expensive airgapped xformer
- An electrostatic screen + using CT windings on the secundary side.
- Keeping high current windings on separate xformers.(heaters for instance)
- Using series regs + high capacitance behind them, chokes help too.
-The other way + some of the above:****
****Use at your own risk, I haven't actually tried this...I think it was TL who proposed it first so I welcome his comments.
At first glance it should be fine but beware of safety measures and use it at your own risk.
Cheers,
Hi,
Indeed that does make a huge difference.
Some ways I know of to go about it:
- An expensive airgapped xformer
- An electrostatic screen + using CT windings on the secundary side.
- Keeping high current windings on separate xformers.(heaters for instance)
- Using series regs + high capacitance behind them, chokes help too.
-The other way + some of the above:****
****Use at your own risk, I haven't actually tried this...I think it was TL who proposed it first so I welcome his comments.
At first glance it should be fine but beware of safety measures and use it at your own risk.
Cheers,
Attachments
I found very similar circuit in one of Mark Levinson amps http://www.diyaudio.com/forums/showthread.php?s=&threadid=3924&highlight=circuit+explanation+needed
How does one keep DC out of the power transformer? Unless you use capacitors in some kind of bridge between the winding points and the rectifier, there will be DC flowing through the secondary.
How does the above circuit work? Is it a direct coupled circuit to use AC straight from the wall? Otherwise.. there would be no DC through it at all... from what I could tell first glance.
Gabe
How does the above circuit work? Is it a direct coupled circuit to use AC straight from the wall? Otherwise.. there would be no DC through it at all... from what I could tell first glance.
Gabe
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