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Posted by Paul S on
09-24-2017
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One of many issues with dipole speakers is directivity/beaming at HF. I have been firing multiple paper tweeters at various angles on my OB test mules with varying results. Here is Alex's idea for a dipole ribbon:
https://www.madisoundspeakerstore.com/ribbon-tweeters/raal-dipole-140-15d-ribbon-driver/
Pretty cool. I did not look how low it goes because I have never wanted to feature a ribbon sound, only to use it for detail, "air" and ambiance. I know from experience that the dipole idea can work with paper tweeters, and I have long wished my Audaphon ribbons were dipole.
Paul S
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Posted by martinshorn on
09-24-2017
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Hi Paul
Why don't you take any tweeter u like, hook up a second in reverse phase on its back?
Cheers Josh
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Posted by Paul S on
09-24-2017
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Sure, Josh, I have done this, and it does work, as far as it goes. I have for some time used ribbons over 8k, because I like them for top of HF. This one is the only HE, dipole, HF ribbon I have seen. Most efficient HF ribbons are "housed" by their magnets, etc. RAALs might be shielded, but no need for 4 of them if using the dipoles.
Best regards,Paul S
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Posted by martinshorn on
09-25-2017
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hi Paul
I was just checking recently.
My electrostatics work great, they also got excellent radiation in HF as the outer stators are lowpassed, so im using very slim 1 inch stripe (50 inch high) in the center only. Excellent radiation and smooth response up to 35k.
But, the transformer got the classic capacitive load down to 0.1 Ohm near 20k and kills all amps headroom.
So i need a tweeter to cross at 5k and it should integrate well. No easy task.
I found the raal too. Could be nice. I found instructions for DIY Ribbons in the size of Magnepans. Could be even better
Then i found reports saying the alu foil makes noise. Digging deeper, i think i dont want a ribbon anymore.
This one is pretty cool too
https://www.madisoundspeakerstore.com/air-motion-transformers-amt/mundorf-amt27d1.1-dipole-air-motion-tweeter-amt/
Would like to know more like that. Pls share @ everyone
Cheers
Josh
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Posted by Paul S on
09-25-2017
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Josh, I also loved my old RTR HF 'stat arrays, doubled over old Peerless tweeters, but I sold all that Fulton stuff to Dr. Dynaco several years ago. My idea for the 'stats and the ribbons is that I do not depend on them for tone but use them only above 8k Hz or so, just for "effects". One thing with stats and ribbons I'm aware of is efficiency. The RAALs have that, and most others lie about it. Another thing is durability. Most 'stats and ribbons are failure prone, have trouble with "macro dynamics". You can read Romy's ribbon story here at GSC. My main "issue" now is, I need a better, faster way to test prototype speakers in a workable time frame without breaking the bank.
Best regards,
Paul S
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