The laminations of the power transformer should be at right angles to the laminations of the OPTs. If the power transformer is the one on the left, it is correct. Don't forget, if you use a filter choke, it may be a good idea to mount it at right angles to both the power transformer and the OPTs.
EDIT: looks like mcs beat me to it 🙂 25 seconds.... 🙁
EDIT: looks like mcs beat me to it 🙂 25 seconds.... 🙁
Is this where I add one of them annoying "Me three" posts? 😀
Another option, if your filter choke is a small one (like the Hammond 158-series) instead of the X-mounts, is you can put it underneathe the chassis at a right angle to the power and due to the top/bottom offset to the OPT's, there will be minimal pickup....especially if you use a non-magnetic chassis, like aluminum, copper or *real* brass.
Another option, if your filter choke is a small one (like the Hammond 158-series) instead of the X-mounts, is you can put it underneathe the chassis at a right angle to the power and due to the top/bottom offset to the OPT's, there will be minimal pickup....especially if you use a non-magnetic chassis, like aluminum, copper or *real* brass.
It looks OK.
But you can do an experiment! 🙂
Connect a loudspeaker at the OPT outputs and connect at the primary of the power transformer the 110 or 220V.
Place the power transformer or the OPTs at different positions to see what happens with hum.It's a nice experiment!
You don't need to connect anything else!You can do the experiment without the transformers on the chassis.Do it very carefully on your bench.
Be carefull not to touch anything on the secondary of the power tranny
But you can do an experiment! 🙂
Connect a loudspeaker at the OPT outputs and connect at the primary of the power transformer the 110 or 220V.
Place the power transformer or the OPTs at different positions to see what happens with hum.It's a nice experiment!
You don't need to connect anything else!You can do the experiment without the transformers on the chassis.Do it very carefully on your bench.
Be carefull not to touch anything on the secondary of the power tranny
Gday.
Am not sure there is a downside to this approach,
but why not shield them with copper cans.
It deffinetly will not harm the look either.
Am not sure there is a downside to this approach,
but why not shield them with copper cans.
It deffinetly will not harm the look either.
Copper doesn't shield magnetically, as far as I remember. Power transformers are also generally not designed for encapsulation - it will get too hot.
Best regards,
Mikkel C. Simonsen
Best regards,
Mikkel C. Simonsen
Gday.
F.ex: K.E moded marantz products uses copper to shield trans.
but with seperation walls.
would maybe be the thing.
F.ex: K.E moded marantz products uses copper to shield trans.
but with seperation walls.
I was thinking along those lines, so a separation plate
would maybe be the thing.
Some manufacturers use a thin copper layer around the transformer to shield them.It's not a can!A lot guitar amps have this kind of shielding on the transformers.
But even with this you can have hum with wrong positioning!The tranny doesn't look nice,too. 😉
With my experiment you can kick hum at 100%. 😡
But even with this you can have hum with wrong positioning!The tranny doesn't look nice,too. 😉
With my experiment you can kick hum at 100%. 😡
mcs said:
it does not conduct magnetic flux but it shorts the changing magnetic fields that produce interference. much like "flux bands" on EI trannys.
icebear said:
Oh, yeah. Sorry Bjørn, I had forgotten.
With the metal/copper shielding thing, you can always just set up the transformers as shown in your diagram and add the shielding later if you have problems with hum and other rubbish coupling into the OPTs. 😀
Shielding
As we all know it is called electromagnetic field so it has smth. to do with the copper shielding but from my experience you can never shield power T/X which is humming as a beast with only a cooper can. We should put a magnetic material.
http://www.diyaudio.com/forums/showthread.php?postid=490811#post490811
I am using C core power T/X (not double C core,but single) for my 5687 tube preamp which is overdimensioned for its purpose and thus have great AC noice rejection (dual split bobbin) and have enormous 50 Hz hum induced in the vicinity of the whole preamp.Reducing of the hum occurs when I turn the T/X right for 45 degrees in the same plane!Not 90 ,which means that you have to experiment a little bit.Puting a 1 mm. thick magnetic sheet of metal 15x15 cm.piece as a shield from only ONE SIDE of the T/X reduces the hum slightly more and shielding it with cube of the same magnetic material silents the hum totally!
If you don't wish to have problems with making shielding pots than you can only take the T/X away from the cct. for apprx. 50 cm.(make split p/s and cct. boxes). It's dead silent in this way!
Yes, and if you use low gradient resin or wax it can start melting soon or latter.
Hope this help.
Regards,
Yugovitz
djQUAN said:
As we all know it is called electromagnetic field so it has smth. to do with the copper shielding but from my experience you can never shield power T/X which is humming as a beast with only a cooper can. We should put a magnetic material.
http://www.diyaudio.com/forums/showthread.php?postid=490811#post490811
I am using C core power T/X (not double C core,but single) for my 5687 tube preamp which is overdimensioned for its purpose and thus have great AC noice rejection (dual split bobbin) and have enormous 50 Hz hum induced in the vicinity of the whole preamp.Reducing of the hum occurs when I turn the T/X right for 45 degrees in the same plane!Not 90 ,which means that you have to experiment a little bit.Puting a 1 mm. thick magnetic sheet of metal 15x15 cm.piece as a shield from only ONE SIDE of the T/X reduces the hum slightly more and shielding it with cube of the same magnetic material silents the hum totally!
If you don't wish to have problems with making shielding pots than you can only take the T/X away from the cct. for apprx. 50 cm.(make split p/s and cct. boxes). It's dead silent in this way!
Yes, and if you use low gradient resin or wax it can start melting soon or latter.
Hope this help.
Regards,
Yugovitz
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