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In Reply to: RE: My 3 years to the goal of the non-compromise SET and still learning.. posted by aknaydenov on September 15, 2015 at 04:42:22
thank you for your response...
but you did not answer my query about banding of the two halves of the c core...
see my Question #2.
MSL
Builder of MagneQuest & Peerless transformers since 1989
Follow Ups:
mqracing,I'm sorry for the misunderstanding. By "banding together", you mean connected, right? Yes, both halves are functioning together and the transformer can be used in 1:1, 1:2 and 2:1 configurations.
If you mean the steel strip that bands many C core transformers - no, they aren't banded. They are tightened with non-magnetic rods (brass) and thick fiberglass panels.
The panels only tighten the cores together, but do not touch the coils, so there is no damage to worry about.
jusbe, sorry for my late reply, somehow I forgot to answer you in the previous posts.My colleague wounds only on single C cores with double bobbins and uses his own special "asymmetric" interleaving from which he has achieved in one of his best projects 15 Hz at -1dB and 160KHz at -1dB. He prefers square shaped C-cores and has wound projects even on amorphs like AMCC500 from Hitachi. He has wound tubes for tubes like 300B, 2A3, GM70, 4P1L, EL34, 6P45S, 6S33S.
He doesn't have a website, but he records data of his projects on his PC. Unfortunately, many of his measurement data were lots because of a HDD crash. He told me he had some on his new computer scattered and I will do my best to find some and post here.
He is kind of very busy right now, but he told me he plans to increase production soon. Our local audiophile community really hopes he does.
He also winds chokes with split bobbins (6,8) on single C cores. The purpose is to get low stray capacitance, which passes less noise through the choke.Kloss, yes I had. Currently the fifth pair of speakers I've listened to these amps. No complains. Only fullrangers and 2-ways though, never tried "more-way".
Edits: 09/17/15 09/17/15 09/17/15 09/17/15
Yes..."If you mean the steel strip that bands many C core transformers - no, they aren't banded. They are tightened with non-magnetic rods (brass) and thick fiberglass panels.
The panels only tighten the cores together, but do not touch the coils, so there is no damage to worry about."That is what I was asking about. Thank you for your response.
A quick note... many builders I know (including myself) prefer to use non-magnetic phospher bronze bands as opposed to steel material.
As opposed the the panels being made from FR4 board material I would look at using brass due to it's superior rigidity.
Hey, you've shared some good ideas... which I've enjoyed thinking about... and like I said in my first reply, I like your chassis aesthetics (wood with metal sub-plates)... and I suspect that your combo MAY have some sonic benefit in terms of damping and resonance control (behaviour).
That said I am from Missouri (skeptical) of the efficacy of the wood pucks but appreciative that you've not been evangelical about this or any other points you've presented.
MSL
Builder of MagneQuest & Peerless transformers since 1989
Edits: 09/17/15
> Q2. your transformers (specifically the two twin coil single
> C core) are the two halves of the c-cores banded together?
> From the photos I could not "see" the banding (if they are banded).There are 2 clamps (yellow-green thick FR4 top and bottom plates), with long bolts, which keep two core halves together.
Edits: 09/17/15
The top and bottom plates are for mounting the transformers to the chassis. Usually in addtion to a chassis mounting arrangement the c-cores themselves will be banded together. Look at, for examples, audio note or Lundahls.
Builder of MagneQuest & Peerless transformers since 1989
I understand. I wonder though, if the banding is really necessary? What are its advantages compared to "tightening" panels only?
I'm not an expert on c-cores and prefer not to use them whenever possible...
currently I think we only have one product that is built on a c-core and that is because it was originally built on stamped laminations--- of an odd shape which was known back in the day as Westinghouse lams--- they have been obsolete for many years--- so in this case we use a core core which can replicate the shape and dimensions of the original Westinghouse lams.And our TL-404's are banded by a friend of mine in NJ who has a mil spec transformer manufacturing facility.
As I understand it--- when you assemble c-cores there is an optimum amount of pressure that should be used to close the air gap as much as is practical as well as to keep the cores physically stable--- varying the amount of the "closing force" can be illustrated by measuring the inductance of the trans--- you want the force necessary to maximize the L.
And usually (again, as I understand best practices to bee) it is preferable to use two bands side by side (i.e., symmetrically placed along the D dimension of the c-core) to equalize the compression wrought by tightening the bands.
The method your tranneys use... two fiberglass pc boards... with bolts on all four corners... my first thoughts were can you get the optimum clamping pressure without the boards first bending... and my second thought was that you'd want to probably use a "torque wrench" so that you could have equal pressure on all four bolts.
My hunch is... but it is only a gut level intuition... that the bands are better in the respect also of "squaring" the c-cores... that is making sure that the two halves are properly seated squarely over each other...
your tranneys looked like (from a distant photo) they were assembled well...
I am always surprised at how many c-cores I see that fail this basic performance and quality construction step...
MSL
Builder of MagneQuest & Peerless transformers since 1989
Edits: 09/21/15 09/21/15
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