I was thinking of a way to get cheaper output transformers for a project.
Since their job is to impedance match the speaker, what happens if we transform the impedance twice or even three times but putting transformers in series?
for example. a 12v transformer is a ratio of 10:1. so three of them in series would be 1000:1.
if we applied that to an 8ohm speaker it would give a plate resistance of 8000ohms.
Is there a flaw in my theory?
Since their job is to impedance match the speaker, what happens if we transform the impedance twice or even three times but putting transformers in series?
for example. a 12v transformer is a ratio of 10:1. so three of them in series would be 1000:1.
if we applied that to an 8ohm speaker it would give a plate resistance of 8000ohms.
Is there a flaw in my theory?
of coarse I know this....I'm just pondering ideas over morning coffee sitting on the deck.
so to continue the thought...in theory, we could put two line transformers in series to give the proper impedance match of a speaker.
What two 120v transformers would match an 8ohm load?
Hi!
Putting two transformers in series would most likely give very unpredictable results. You should select a matching near the value that is required for the output stage.
Decent output transformers are not expensive. Or salvage some transformer from an old radio. That would give muc better results than arbitrarily ganging two power transformers together
Thomas
Putting two transformers in series would most likely give very unpredictable results. You should select a matching near the value that is required for the output stage.
Decent output transformers are not expensive. Or salvage some transformer from an old radio. That would give muc better results than arbitrarily ganging two power transformers together
Thomas
Yes yes i know, use the proper part for the job. I am.
I'm merely thinking out loud on a theory.
by the calculations a 120v primary and a 5-6v secondary would match a 8ohm load with roughly 3300-4600ohm impedance, with only one transformer. (obviously a power transformer is not designed properly for audio applications. again I know this.)
So two transformers in series to give 5-6v out would do the trick, technically speaking...
I'm merely thinking out loud on a theory.
by the calculations a 120v primary and a 5-6v secondary would match a 8ohm load with roughly 3300-4600ohm impedance, with only one transformer. (obviously a power transformer is not designed properly for audio applications. again I know this.)
So two transformers in series to give 5-6v out would do the trick, technically speaking...
Most (all?) power transformers aren't air gapped, so single ended is out. You would need a dual primary 240v (120-120v) transformer for push-pull. I prefer toroids since in general they have a wider usable bandwidth compared to EI transformers. I've used a single primary toroid in a parafeed arrangement:
http://www.diyaudio.com/forums/tubes-valves/211352-new-amp-13de7-se-hybrid.html?highlight=13de7
http://www.diyaudio.com/forums/tubes-valves/211352-new-amp-13de7-se-hybrid.html?highlight=13de7
Sorry to be blunt, but if you don't understand transformers what facts do you have to base your thinking on?
Things you need to learn about include: magnetic saturation and air gaps, magnetic hysteresis, impedance transformation, primary inductance and LF response, leakage inductance and HF response, stray capacitance and HF resonances. Once you can begin to understand these issues then you can begin to think meaningfully about transformers.
Things you need to learn about include: magnetic saturation and air gaps, magnetic hysteresis, impedance transformation, primary inductance and LF response, leakage inductance and HF response, stray capacitance and HF resonances. Once you can begin to understand these issues then you can begin to think meaningfully about transformers.
Your goal is to understand this plot: File
ermeability by Zureks.svg - Wikipedia, the free encyclopediaTry to read and understand this:
Magnetic field - Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Permeability_(electromagnetism)
You think you can achieve that ? It is not that hard when you get the deal with fluxes and flux densities.
there is more, a lot more....once you have the ratio all figured out, then you have to find out iron power handling, core saturation and frequency response...
power transformers are way too easy, they are only asked to work on either 50 or 60 hertz, sometimes 400.....
working on hacking the output transformers requires a lot of study.....
Oh come on guys, do not need one semester in college to learn something about transformers.
I know people as ignorant as me and make excellent transformers.
Try this
http://www.diyaudio.com/forums/tubes-valves/181072-designing-transformers-j-c-maxwell.html
Do not be afraid to calculations, just use the main results.
I know people as ignorant as me and make excellent transformers.
Try this
http://www.diyaudio.com/forums/tubes-valves/181072-designing-transformers-j-c-maxwell.html
Do not be afraid to calculations, just use the main results.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.