Transformer core size increases primary inductance which in turn is better for low frequency response.
But,-there's always a trade off. Overdoing one single parameter usually make other parameters suffer.
Any thoughts?
But,-there's always a trade off. Overdoing one single parameter usually make other parameters suffer.
Any thoughts?
These are my thoughts on the matter.
A Consequence of The Quest for 20Hz Roll Off
Your Mileage May Vary.
A Consequence of The Quest for 20Hz Roll Off
Your Mileage May Vary.
The self inductance of a simple coil is defined as L = µ*N^2*A / 2πr. So as area is increased the inductance goes up. Area increases as the square of radius so, all things being equal, doubling the size (i.e. cross sectional area) of the core will double the inductance. This is simple physics.
Regarding capacitance . . . I would guess it would increase too (correct me if I'm wrong).
More cross sectional area . . . longer magnet wire . . . more capacitance.
No free lunch here,-what you gain in low frequency response is paid for in the high frequency end of the spectrum and vice versa.
It's all a balancing act.
More cross sectional area . . . longer magnet wire . . . more capacitance.
No free lunch here,-what you gain in low frequency response is paid for in the high frequency end of the spectrum and vice versa.
It's all a balancing act.
Low frequency response depends on primary inductance.
Primary inductance depends on several variables, one of them being effective core cross section area.
Other variables are: Turns number squared, core material (B/H characteristic determining AC amplitude permeability and saturation) and effective air gap.
So its possible that a smaller size OT has a larger primary inductance.
Primary inductance depends on several variables, one of them being effective core cross section area.
Other variables are: Turns number squared, core material (B/H characteristic determining AC amplitude permeability and saturation) and effective air gap.
So its possible that a smaller size OT has a larger primary inductance.
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The higher the core area, the better.
The drawbacks are higher volume, weight and cost.
With higher core area, one needs to decrease the number of primary turns, then the amount of interleaving accordingly.
Lower interface interleaving types have the benefit of better Cps reduction vs Ls .
The drawbacks are higher volume, weight and cost.
With higher core area, one needs to decrease the number of primary turns, then the amount of interleaving accordingly.
Lower interface interleaving types have the benefit of better Cps reduction vs Ls .
Of course, one can always go to the extremes of tube madness, as in the amorphous double-C core of the S-833 OPTs Monolith Magnetics made for my amps. The OPTs weigh 60lbs each.
Attached is a picture Monolith sent during construction, with an ECC83 tube for comparison.
Attached is a picture Monolith sent during construction, with an ECC83 tube for comparison.
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In a topic influenced by many factors, ambiguity can be avoided by defining aspects like 'core size'. Yes size can be associated with core cross sectional area A, but some may not immediately relate the two. Changing A also typically has a consequence on magnetic path length r, and often requires a practical alteration of other design aspects.
As emtor prefaces, there are many interactions, and many types of core material, and many styles of core shape and construction, and many operating limits applied to voltage and frequency that can influence the choice of something as 'simple' as a core.