Anyone using Fountek NeoCD 2.0 5" ribbons? - diyAudio
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Old 18th November 2014, 12:16 AM   #1
milosz is offline milosz  United States
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Default Anyone using Fountek NeoCD 2.0 5" ribbons?

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If you are using this 5" ribbon, what frequency are you crossing over at?

I'm playing around with an active (biamp) 2-way with a Satori 6.5" woofer and a Fountek NeoCD 2.0 ribbon.

I'm crossing over at 3 kHz / 48 dB per octave Linkwitz-Riley topology using a MiniDSP/MiniDIGI.

I have to say I'm not terribly happy with it so far. There's a lower treble / upper midrange roughness to the sound, even though the THD looks OK in the tests I've run...


Click the image to open in full size.

Last edited by milosz; 18th November 2014 at 12:28 AM.
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Old 18th November 2014, 02:53 AM   #2
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That's the Satori breakup and fwd lobe from beaming at too high a crossover point. You need a small format( 4-5") midrange in between with ribbons. The 2.0 is an amazing tweeter from 3.5kjz on up......extremely linear and smooth.
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Old 18th November 2014, 09:15 AM   #3
milosz is offline milosz  United States
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I changed the crossover to 2250 Hz, and, in fact, it did sound BETTER. You are right, I was trying to use the Satori up too high.

2250 is too low for this tweeter, distortion in the lower part of the treble will get ugly at anything approaching loud. However, as a test, changing the crossover down lower did prove that the problems were coming from the Satori approaching it's breakup and having a funky radiation pattern at so high a frequency.

Here's FR and harmonic distortion curves with a 2250 xover
Click the image to open in full size.
This is a bi-amp project so a midrange driver - like a Morel MDM55- is really not an option. None of the Fountek ribbons will work low enough in frequency; I'm told the Raal 140-15D ribbons will, but they're quite costly. I might just pry the wallet open and spring for some Raal ribbons, I've wanted to use them in a project since I heard about them... but still... $630 each.... wow.

Maybe I'll try one of the larger Dayton AMT tweeters, like the AMT 3-4. $200 a pair. Or maybe the Dayton AMT Pro-4 which is $300 a pair and better down below 3 kHz. Or maybe the Aurum Cantus AST2560, $340 a pair. Ribbons they are not, but they should work down to 2 kHz. (I could use some kind of dome or ring, but I am bored with domes.)

There is also the Aurum Cantus G3 ribbon which they claim will work down to 2300 Hz. I dunno. I have a feeling it will have the same kinds of distortion issues that the Fountek has. And, they are not cheap -$420 a pair.
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Old 18th November 2014, 09:22 AM   #4
milosz is offline milosz  United States
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OK so I ordered a pair of Dayton Audio AMTPRO-4, http://www.parts-express.com/pedocs/specs/275-094s.pdf

We'll see how that sounds. This is an experiment...

I had the Fountek NeoCD 2.0's laying around, and thought I'd try them...they are good used at higher frequencies, but I need to cross over around 2,000~2,500 Hz. I think these AMT's ought to work well down to that range, but they're not going to have the fast settling times etc of an actual ribbon. Maybe that will work to their advantage, though - maybe their overall characteristics will blend better with the Satori 6.5" woofers.

We will see.
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Old 22nd November 2014, 12:08 PM   #5
milosz is offline milosz  United States
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Dayton AMTPRO-4's arrived. Just temporarily hung them on the front of the speakers and ran some curves....

The new 2-way project is perched on top of a floor standing project that is dormant at the moment, ignore that
Click the image to open in full size.

Initial curve; blue is THD, red is 2nd harmonic, etc
Crossover is 1800 Hz 48 db / octave L-R
Click the image to open in full size.

These Dayton AMTPRO-4's are rated 94 dB /1m / 1 watt, but I think that's a bit optimistic.

The sound was quite different from the Fountek ribbon. There was more detail in the mids / lower treble, although I think the Fountek has a little better upper treble "bite" and extension. Even so, the AMT sounded more realistic in this application than the Fountek ribbon, mostly I think because it could be crossed over lower. Also, I think the AMT is a bit more "dynamic" in the lower treble. MUCH more listening and testing is needed.

FYI I am using a very small (~1 watt) S.E. tube amp to drive the tweeters, and this amp is not adequate to drive the AMT's; the slight rise in THD above the crossover point is due to the amplifier. The Fountek ribbons were about 4~5 dB more sensitive and the little tube amp could drive them nicely; these AMTs want a bit more power. I am finishing up a small class A solid state amp that I will use for the AMT, I'll plot some more curves once I finish that and I expect the THD to be lower with that amplifier.

I have also ordered a pair of ribbon tweeters from Selah Audio, and Rick at Selah says they have low distortion and can be used down to 1800 Hz. I will try those as well, once they arrive.

With these AMTs and the ribbons from Selah, I will have to pick one or the other for these two-ways. The driver I DON'T use here will later go into another speaker project that's languishing in my workshop...

Last edited by milosz; 22nd November 2014 at 12:11 PM.
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Old 22nd November 2014, 02:37 PM   #6
Scott L is offline Scott L  United States
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Default in-line cap ?

greetings,

Are you using an in-line, series capacitor to the ribbon (or driver of your choice) ?

Use a value that will give an Fcx at one octave lower than what your active crossover does. This offers a startling increase in clarity.
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Old 22nd November 2014, 04:59 PM   #7
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I am using these in a line array designed by Rick Craig of Selah Audio. If you get in touch with Rick I'm sure he'll be very helpful.

Regards,
Dan
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Old 22nd November 2014, 05:11 PM   #8
system7 is offline system7  United Kingdom
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How dumb is it to use a tweeter with a vertically aligned radiation pattern with a standard woofer?

This tweeter is best used in an MTM. Seemples. Then the radiation of the woofers and tweeter falls off similarly with distance. You guys are so dumb. Sorry.
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Old 22nd November 2014, 11:34 PM   #9
milosz is offline milosz  United States
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Quote:
Originally Posted by system7 View Post
How dumb is it to use a tweeter with a vertically aligned radiation pattern with a standard woofer?

This tweeter is best used in an MTM. Seemples. Then the radiation of the woofers and tweeter falls off similarly with distance. You guys are so dumb. Sorry.
Not applicable to nearfield use.

Here's another speaker I built, designed for normal room type listening rather than nearfield use:

Click the image to open in full size.

Last edited by milosz; 22nd November 2014 at 11:54 PM.
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Old 22nd November 2014, 11:37 PM   #10
milosz is offline milosz  United States
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Quote:
Originally Posted by Scott L View Post
greetings,

Are you using an in-line, series capacitor to the ribbon (or driver of your choice) ?

Use a value that will give an Fcx at one octave lower than what your active crossover does. This offers a startling increase in clarity.

That's interesting. No, I don't have a capacitor in series with the AMT. I assumed that since I am using a tube amplifier (transformer coupled...) there was no risk of DC on the output... and in my case, due to the poor LF performance of the tiny amplifier, no risk of bass either....

I'll give it a try. I have a bunch of good quality film caps laying around of various large values.
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