Hi,
I'm looking at my next valve amp. build using an existing chassis and see that a certain Power Transformer supplier is offering a number of options for the same footprint/cutouts. The options include 3 variations in height, as designated in the title. Only a single spec. is listed:
Input voltage: 0-220V-230V (default) Output voltage: each winding voltage can be made according to customer requirements a), 380V-330V-0-330V-380V DC=0.2A, b), 5V/3A (rectifier filament winding), c), 0V-2.5V-6.3V/3A d), 6.3V/3A
The price varies quite a bit and the supplier is stating (incorrectly?) the current ratings are the same in each case. I would think that more iron would indicate higher power rating? Or am I missing something here?
Thanks in advance!
I'm looking at my next valve amp. build using an existing chassis and see that a certain Power Transformer supplier is offering a number of options for the same footprint/cutouts. The options include 3 variations in height, as designated in the title. Only a single spec. is listed:
Input voltage: 0-220V-230V (default) Output voltage: each winding voltage can be made according to customer requirements a), 380V-330V-0-330V-380V DC=0.2A, b), 5V/3A (rectifier filament winding), c), 0V-2.5V-6.3V/3A d), 6.3V/3A
The price varies quite a bit and the supplier is stating (incorrectly?) the current ratings are the same in each case. I would think that more iron would indicate higher power rating? Or am I missing something here?
Thanks in advance!
Power = Voltage x Current.
So with the current ratings staying the same, more iron for 380V-0-380V than for 330V-0-330V and more iron for 0-6.3V than for 0-2.5V seems logical to me.
So with the current ratings staying the same, more iron for 380V-0-380V than for 330V-0-330V and more iron for 0-6.3V than for 0-2.5V seems logical to me.
In my youth I've learned that a power tranny's power capability (in VA) is the square of the iron cross section (in cm²) in the center leg. I didn't know of different steel qualities then, but I assume that the proportionality still holds true for transformers made from the same steel.
Best regards!
Best regards!
I've copied direct rom their ad, but they are not citing different voltages between variations. They are quoting exactly the same spec. for each variation. Ie: Each Tx has 380-330-0v output taps, at the same 200mA rating, plus the same filament voltage windings and current ratings.
I commercially wind transformers.
In principle, yes, more iron means more power handling capability, BUT winder may choose to use that extra capacity to get a "same (voltage/current) spec but lower DCR" transformer, which in due time will have better regulation, meaning lower voltage drop under load.
Designs always involve a compromise, having more iron available may reduce constraints in other areas.
Also meaning: "same nominal specs does not mean they are all the same".
In principle, yes, more iron means more power handling capability, BUT winder may choose to use that extra capacity to get a "same (voltage/current) spec but lower DCR" transformer, which in due time will have better regulation, meaning lower voltage drop under load.
Designs always involve a compromise, having more iron available may reduce constraints in other areas.
Also meaning: "same nominal specs does not mean they are all the same".
Thanks for your reply - and much appreciated as you are clearly very knowledgeable on the subject. It wouldn't surprise me that the seller hasn't a clue about what they are selling as they will be an AliExpress middle-man. I have an existing chassis which therefore has pre-defined mounting holes. The 'taller' Power Tx I assumed would be a higher wattage, however I'm getting no sense from the suppliuer as they just quote same OP voltages, taps and current ratings for each winding. I'll maybe plump for the middle one and see what I get 🙂
i design and build power and audio output traffos used in my amps, but just a hobby, i do not sell traffos...
yes, the bigger the core cross section area, the bigger the capacity, but the sizes you mentioned are not night and day difference wrt capacity...
core material quality plays a lot, an M6 grain oriented steel can be made smaller than a non GOSS steel.....
yes, the bigger the core cross section area, the bigger the capacity, but the sizes you mentioned are not night and day difference wrt capacity...
core material quality plays a lot, an M6 grain oriented steel can be made smaller than a non GOSS steel.....
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