100V Output Transformer - there is a formula to translate Volt to ohm impedance?

[kagliostro]

Yesterday evening I put the question in a wrong way on another thread that I deleted now

the right question I want to put is:

assuming (as example) we have an OT with 6.000ohm plate to plate primary impedance and 100v secondary output

there is a formula to calculate in ohms the impedance ratio of the secondary ??

100v = XXohm ?  

Thanks and excuse me for the previous wrong way putted question

Kagliostro

[mat janssen]

If you want to use 100 V transformers in a speakersystem, you have to know two more extra things.
The output power of the 100 V amplifier, and the input power of the speaker"system" where the other transformer is placed.

If you know ohms law now, then you can complete you calculation I guess !

P = U^2/R !!

[RicharD]

Turns ratio squared times load impedance = primary impedance.    Here's what you need to do:

Inject a small AC voltage into the primary.  Measure the actual voltage of the primary and the secondary.  Now you have 2 measurements which is the voltage ratio of the transformer.  Voltage ratio = turns ratio.  Now you can plug these values into my original equation:  TR^2 * Rl = Zin.

It has been my experience that even with a Rl as high as 16 ohms, these old intercom output transformers are not really usable.  They were designed to push a signal across a long wire and have several taps, each with an impedance matching transformer placed between it and the speaker.   

[PRR]

> impedance ratio of the secondary ??

As they said: you need to know designed Power.

But another way to look at it. The OT is designed to deliver 100V. Do you have any speakers which can work on 100V? 30 Watts at 4 ohms is 11V. 60 Watts at 16 ohms is 32 Volts.

You could stack twenty 16-ohm speakers in series.

You could find the 100V-8ohm speaker transformers, but they are usually 5W-10W each so you need a lot of transformers and speakers.

You could add a 120V:24V transformer step-up to run small 120V 60Hz gear in a 230V 50Hz land.

[darryl]

If I remember correctly, the original thread was about output transformers in jukebox amplifiers.   

It might be worth a closer inspection, because there may be several secondary windings - one for 100 volt line, and another for voice coil impedances.

[kagliostro]

Thanks to ALL

This was a question academic

as to learn more about this argument

so I have no one of this transformer to investigate about

If I had one I can apply the math about the voltage ratio or use The CESVA MPI-3 Impedance & Power Meter that I received as a present from a friend some yeas ago

That is a very interesting instrument that I admit don't know enough to make the most

PRR will remember that he teached me how to use it to investigate about transformers impedance

only one thing PRR

You could stack twenty 16-ohm speakers in series.

why 20 speakers ? the output is 100v and you told 60 Watts at 16 ohms is 32 Volts

32volts ..... x 20 will give much more than 100v

Thanks again

Kagliostro