What transformer are you considering? I just spent about an hour looking around online and I can't find a transformer that's still available that's designed to do this.
Of course I have not found the transformer I need!
Why do you think I have been spending time posting here and other forums?
Not for the civil discourse.
LOL
All kidding aside, thanks for spending the time.
I hoped not to bother him, but it looks like I have to talk to one of the Great Audio Gurus.
Only the old dogs remember what a transformer is for and more importantly where to find one.
OMG!
Is it really Too Tall from the old "Bass List"?
Welcome to the diyAudio Forum!
Curtis,
I'm not sure if it may be exactly what you're looking for, but O'Netics (here in the PNW) does SOTA custom transformers and the designer, Bud Purvine, just happens to post here under BudP. You might contact him and see if he can do a transformer for you that fits your needs. If nothing else, Bud could probably tell you who might have what you're looking for.
As far as civil discourse, I suspect that several people may have assumed (incorrectly) from the number of posts that you're a relative newcomer to audio.
Note: To those who don't know Curtis (Too Tall), he has been in Pro Audio for several decades and is certainly an extremely knowledgable person when it comes to sound. He was one of the mainstays on the old Bass List, which had "a lot" of the very top names in Audio as members.
Best Regards,
TerryO
Being an old dog, I still know what transformers are used for.
The last time I bought an transformer capable of low distortion high power LF output, it cost (and weighed) more than a speaker of similar power rating, and it was a stock item back in the mid 1980's.
Before that, I recall lugging a 120 pound Macintosh 2300 around, it had a pair of 300 watt autoformers (unusual for a transistor output amp) about half of the amp's weight was in the autoformers.
Autoformers don't provide electrical isolation, they are lighter than transformers...
If you don't want half (or more) of the power wasted in the transformer, 60 pounds for a low distortion transformer capable of around 1000 watt 30 Hz output would be a reasonable guess, it will not look like a ceiling speaker 70V line transformer.
A 2 in, one out transformer is a weird duck, it will probably have to be wound for your specific application.
It could perhaps include the inductance needed for the LF passive crossover in the same package, saving some weight and expense, as you know, LF inductors that don't saturate at high power are heavy and expensive.
Community Sound might be a help in pricing a transformer, but I'd expect anyone making a beast that would work for your application would want a minimum order of more than the potential market for such a goofy product.
Art
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Hi Art,
I got a reply from Tom Danley on what to try.
Tom warned me about using autoformers.
No isolation so the outputs try to "drive" each other.
Just what I knew I had to avoid.
He clued me in on the progression for magnetic saturation.
By the time you get down to 30Hz the voltage may be limited to 65volts before saturation.
Oops!
It the same thing I run into with dipole speaker (ESL). After the wavelength is longer then the width of the baffle the response drops 6dB/octave.
I did not think the transformer slope would be quite that bad.
Thanks for the help.
Hi Terry,
Thanks for the tip BudP.
After reading replies from Art and Tom the size and weight will eat this project alive. I was not surprised, but I had to ask around and find what the numbers were before I dismissed it out of hand.
BTW, a while back I wanted to lose some weight on inductors. I asked around about using aluminum wire. The fly in the soup is you need more wire to get the same value so you are going backwards.
TANSTAAFL
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