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Old 20th April 2003, 01:56 PM   #11
GaryB is offline GaryB  United States
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Default to clarify

In case I wasn't clear in my earlier post (its early morning in NY), even though I was explaining how I positioned the output transformer relative to the power transformer in my amps, the point was that one can actually measure the magnetic field from a power transformer by measuring the coupling into another magnetic component such as a choke or another transformer. Thus you can sniff around and see where the magnetic field is weakest and put your tubes in that location.
---Gary
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Old 20th April 2003, 02:25 PM   #12
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Default Re: to clarify

Quote:
Originally posted by GaryB
In case I wasn't clear in my earlier post (its early morning in NY), even though I was explaining how I positioned the output transformer relative to the power transformer in my amps, the point was that one can actually measure the magnetic field from a power transformer by measuring the coupling into another magnetic component such as a choke or another transformer. Thus you can sniff around and see where the magnetic field is weakest and put your tubes in that location.
---Gary

OK,AgryB,read you loud and clear!
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Old 20th April 2003, 03:08 PM   #13
EC8010 is offline EC8010  United Kingdom
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Default Re: the empirical method

Quote:
Originally posted by GaryB
Theory is great but nothing beats reality.
Absolutely. I've measured for optimum relative positioning between transformers, rather than looking for a quiet place as you've suggested for valves. It must be time for the search coil to come out again!
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Old 20th April 2003, 05:51 PM   #14
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Default english lesson

Hmmm.....
I am truly sorry that I must ask this question, because I understand that the answer was clear, BUT my lack of english maks me confused.....
"whose coils should be pointed at a right angle to these valves"
To me that could be just anything... (if I turn it 90 deg, its still right angle...or??) Is there any scheth or easy drawing that explains this for a non englih speaking dumb swede?

Also: Whats the pro and cons of using aluminum vs steel. Steel is magnetic is that good or bad? Will it absore the magnetic field or will it take the field to places were I don't want it? I think theres something called my-metal (u-metal) but thats out of reacf for me.

Thanks a lot

björn
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Old 20th April 2003, 09:37 PM   #15
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Arrow --> björn!

http://home.swipnet.se/sm6xun/gear/x-former.bmp
this picture should describe the problem, a transformer has a magnetic flux surrounding the core, that will cause hum if your transformer isn't shielded with, for example, µ-metal (my-metall)
-this is what GARY_B meant with his 90º degrees angle...

in swedish: rören bör inte monteras i "kortänden" på trafon, utan på sidan..hoppas att ritningen är förklarar!
-lycka till!

when doing magnetic shielding, i prefer thin coppersheets, solderable and easy to work with, pretty good shield too, better than aluminium anyhow.
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Old 20th April 2003, 10:02 PM   #16
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Mr. Triatic or may I adress u xun?:


Very easy to understand your drawing. Thank u very much or in swedish:
Tack så mycket.
But I'm still puzzled over that I read some where that the power-supply transformer and the output tranny should be 90 deg apart. Is it so and than why? .To cancel out the fields ..or?

And where can I take up some more info on the metal-stuff?

cheers,
björn
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Old 20th April 2003, 10:07 PM   #17
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Quote:
Originally posted by ShiFtY
Another thing you might want to consider is heat. Make sure you have at least half an inch or more around the rectifier and power tubes so that air can circulate.

Re: hybrid diode/tube rectification, I plan to try this at some stage, using UF4007 high speed diodes and a 5V4, you get the benefits of slow warm up and no "switching" noise (which I have never been able to hear anyway )

Hi ShiFtY,

Can you tell me/us more about the hybride rectifications using the UF4007?

Thanks in advance,

Audiofanatic
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Old 20th April 2003, 10:26 PM   #18
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Default HYBRID RECTIFIER.

Hi,

Quote:
Can you tell me/us more about the hybride rectifications using the UF4007?
It works with any pair of diodes, really:

Cheers,
Attached Images
File Type: gif hybrid_pwd.gif (22.7 KB, 284 views)
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Old 20th April 2003, 10:40 PM   #19
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Thanks Frank,

How it's clear to me and I'll try it out on my next project my 300B and my SE EL34!

Audiofanatic
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Old 20th April 2003, 10:59 PM   #20
EC8010 is offline EC8010  United Kingdom
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Default Re: --> björn!

Quote:
Originally posted by Mr. Triatic
http://home.swipnet.se/sm6xun/gear/x-former.bmp
I hate to say it, but that diagram is wrong. The lines of flux shown are incomplete, and do not show the straight line that comes out of the axis of the coil. Valves should not be on the axis of the coil.

Steel can be a problem. If you mount a toroid or a drop-through transformer on steel, flux will be carried to places you don't want. This is the reason why some amplifiers mount drop-through transformers on plastic spacers. The spacers are effectively a magnetic resistance, and prevent flux from entering the steel chassis.
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