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In the Forum: Horn-Loaded Speakers
In the Thread: RAAL “Water Drop” tweeter for Macondo.
Post Subject: Other amps for other HF ribbonsPosted by Paul S on: 2/21/2007
I have tried both SS and tubed PP with HF ribbons, but not until ML2s have I gotten the "calm HF" I wanted from the ribbons.  I am still experimenting with the Audaphons, but they seem to do best from 4 Ohm tap.  My little 2A3 SETs did not sound "bad", but they just did not seem to have the push up there to "get through" to make the ribbons work; they pretty much just rolled off.

I would have to say from memory that PP tube and SS were about equally "excited HF" with the ribbons, take your choice.  I did not measure levels but I got more of it than I wanted with a theoretical/mathematical match to the silk dome tweeters I ran them over.  With PP tubed amps I actually preferred an electrostatic array rolled in over 7.5k.  That could be just a better match for the silk domes, but I rather suppose that the PP just worked better with the 'stats and ovbiously had phase problems (or sounded like it) with the ribbons.

I have only heard OTL with "full-range" ribbon system, and it was just too confusing to say anything about HF only, although some version of OTL does seem like the final destination of the "dedicated" HF ribbon amp, given all perfect electrical matches and ignoring, of course, any other issues with matching the rest of the system.  In other words, it seems like a pretty much impossible task, at least for me.

I think all my ribbons are about 8 - 8.5mm wide.  Audiphons are over twice as long as Arum Cantus I used, and supposedly they are both 96 dB, although the Audaphons are obviously at least 3 dB more efficient, and they are considerably more efficient from 10 - 20k.  Arum Cantus only seems to "take off" above 20k, like a typical MC cartridge.  Not bad, really, but just a note, and may aggrevate/cause apparent suck out of lower frequencies.  Wider ribbons did not work as well for me for top HF only, no matter the amps.  I have not tried significantly narrower ribbons, nor more efficient, since those commonly available with any power at all are wide and/or coated.  I have not measured anything electrically because it is so easy to blow these ribbons while "testing" them.
Speaking of "blowing", I have also made the fatal-to-the-ribbon mistake of trying to gently blow a speck of dust off one of them.  Don't try this at home!

Best regards,
Paul S

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