Any transformer under no load will give more than the advertised secondaries voltage. Under a very big load that voltage will drop , sometimes more than the advertised voltage. But after rectifying the dc voltage will be around 1.4x the secundaries voltage, regardless of the load.
Am I wrong?
Am I wrong?
Attachments
Last edited:
Wow, a 180 degree change using the edit button. Well done.
55VAC @ 1000VA is the transformer rating. It has to deliver this or it is in default of its specification.
What you are arguing about is called regulation. 40% would be terrible for transformer regulation.
"The voltage regulation of the transformer is the percentage change in the output voltage from no-load to full-load."
The Basics of Transformer Voltage Regulation | Electrical Construction & Maintenance (EC&M) Magazine
Last edited:
the point is: 2x55Vac sec transformer will give you around 375W average at 8ohm.
55x1.41=77.5Vdc rails. 77.5x0.707=54.8Vrms. 54.8x54.8/8=375W average at 8ohm and not 180W.
however. this is a teoretical ideal world. in the real world there will be some voltage loss. how much depends on the amp.
55x1.41=77.5Vdc rails. 77.5x0.707=54.8Vrms. 54.8x54.8/8=375W average at 8ohm and not 180W.
however. this is a teoretical ideal world. in the real world there will be some voltage loss. how much depends on the amp.
Last edited:
The 40% "lost" refers to the heat dissipation from the transistors not the transformer.
That's 60% true. But the transistors eat power too for the heat sink. I have an 150W amp that dissipates 50W into the heat sink.
heat disipation got nothing to do with it. that do not change any voltage sving. it's the same calculation if its class A class A/B or class D or what ever.
the heat disipation is the result of consumed current at the given voltage by the outputs. and there is ofcourse a couple of volts lost in the outputs too.
i have a 25W amp that dissipates 125W at the heatsink at idle for each ch. but still, +/-24V rails still gives me 25W average at 8ohm.
the heat disipation is the result of consumed current at the given voltage by the outputs. and there is ofcourse a couple of volts lost in the outputs too.
i have a 25W amp that dissipates 125W at the heatsink at idle for each ch. but still, +/-24V rails still gives me 25W average at 8ohm.
Why are you are you arguing? You are still wrong.
This calculation is simply wrong. If the transformer is rated for 55VAC at 1000VA then the rails can be +/- 76VDC. The output can be 54Vrms - active device headroom required, not 38Vrms. Don't ******** that you accounted for real world losses, those don't magically equate to sqrt(2).
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.