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Old 21st August 2012, 03:58 PM   #6901
Salas is online now Salas  Greece
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Quote:
Originally Posted by Joachim Gerhard View Post
Yes, Toroids have the lowest stray field if you mount them right.
R-Core has minimal stray field, not the toroid. The toroid is very offensive in same box with MC preamps for harmonic noise. Its most offensive side is the secondary wires exit area. I am pretty sure because I have tried those things together many times. It takes a grounded copper shield around it and/or a grounded ferromagnetic container to tame it if it must be in the same box. Maybe you talk encased toroids as low stray field?
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Old 21st August 2012, 04:10 PM   #6902
RCruz is offline RCruz  Switzerland
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Quote:
Originally Posted by Salas View Post
R-Core has minimal stray field, not the toroid. The toroid is very offensive in same box with MC preamps for harmonic noise. Its most offensive side is the secondary wires exit area. I am pretty sure because I have tried those things together many times. It takes a grounded copper shield around it and/or a grounded ferromagnetic container to tame it if it must be in the same box. Maybe you talk encased toroids as low stray field?
I agree.... I have built some riaa amps with a r-core tx inside the case without trouble.... also did the same with toroids and could never get rid of induced noise... I could silence one channel but the other picked up like an antena.

Turning the toroids one against the other somehow minimizes the problem but never cures it alltogether.

Heavy screening is needed.

Anyway ... r-cores sound so much more effortless... it is incredible
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Old 21st August 2012, 04:12 PM   #6903
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What i wanted to say is that toroids have low stray field in one direction and high stray fields in other.
Anyway, i always put the transformers in a separate box anyway.
I use R-Core sometimes too and get them from Japan.
For my own builds i use Block Spit Bobbin. They are economical and work well.
As a said many times, i am not a great PSU builder, nevertheless i get my builds super quiet.
In September i plan a Paradise Fest at my home and then we can compare.
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Old 21st August 2012, 04:25 PM   #6904
Salas is online now Salas  Greece
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Split bobbin are a good economical solution if in different box. Because they make the primary/secondary separation. Its the right angled corners of the iron frame that still emit field VS the rounded R-Core. But the capacitance is lower VS the toroid that has the primary and secondary windings on top of eachother. Even the EI has plastic formers that provide some little separation. EI has its less stray field to its side by the way. Some EI are excellent for audio but need kept separate box for low signal high gain too. Heck, even the mains primary wires are offensive to a point. Best is two box far away, anyway.
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Old 21st August 2012, 04:26 PM   #6905
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Just placed an order for a pair of AN-0220 :
Antek - AN-0220
25VA - 2x20V - 4.096cm High - $40 shipped
Thank you Joachim about the hint concerning stray field.
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Old 21st August 2012, 04:32 PM   #6906
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I am building an external case for the psu... the only wire I got here is 23AWG microphone cable.... Is that inapropriate for connecting between the psu and the amp case ?
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Old 21st August 2012, 04:37 PM   #6907
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Originally Posted by korben69 View Post
Just placed an order for a pair of AN-0220 :
Antek - AN-0220
25VA - 2x20V - 4.096cm High - $40 shipped
Thank you Joachim about the hint concerning stray field.
This is what I like, the correct voltage and slightly over powered Put them in their own box, iron not aluminum or copper, and you will have adequate power. The boxed transformers may be placed in the same box as you paradise but then I would advise to box the paradise also, copper not aluminum or iron. Like here Balanced input all DC coupled RIAA preamp #4
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Old 21st August 2012, 04:43 PM   #6908
FdW is offline FdW  Netherlands
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Originally Posted by RCruz View Post
I am building an external case for the psu... the only wire I got here is 23AWG microphone cable.... Is that inapropriate for connecting between the psu and the amp case ?
AWG, what’s that? used for washing machines or locomotive’s? AWG conversion table It seems a bit thin, but I like to oversize, 23 AWG (or 0.25 MM2) is to thin, use 1 MM2 (or 17 AWG) and thicker (for external wiring connecting the boxes).

Or go extreem, use 4 times RG214

Last edited by FdW; 21st August 2012 at 04:45 PM.
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Old 21st August 2012, 04:49 PM   #6909
Salas is online now Salas  Greece
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Originally Posted by FdW View Post
Or go extreem, use 4 times RG214
That's handgun calibre coax.
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Old 21st August 2012, 05:13 PM   #6910
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Quote:
Originally Posted by FdW View Post
Or go extreem, use 4 times RG214
Why didn't I think of that.
RG59 Coaxial shielded cable for input wiring?
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