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Old 22nd November 2008, 08:28 PM   #211
Telstar is offline Telstar  Italy
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Location: Italy
Default Re: Re: Re: First Watt and Lowther at RMAF

Quote:
Originally posted by Nelson Pass
It's still set up as a 4' X 6' OB. I replaced the PHL 18" drivers
with some Taiwanese OEM 18" that I got - light paper cones
with big magnets and voice coils. Much better due to the lighter
mass and the very low resonant frequency. As a result I'm
going to stick with these for a while.

I need to finish documenting these and the crossover performance,
and then the Lowther PM6A Ticonal/16 ohm silvers go in for another
comparison against the D9nf's.

After that, the PM6A without Ticonal, and PM6A's stock and the
Moths.

Probably then the D55's / A55's / C45's

The the SEAS Exotics

Then all the Audio Nirvanas.

Then the Fostex 166E, 166E with the bih magnets, and the 206E's

Then I'm going to start cutting the baffle width down in 6 inch increments
and experimenting with foam side diffusors.

It's going to be a long fall and winter....


Admirable dedication ))
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Old 23rd November 2008, 12:26 AM   #212
bvan is offline bvan  Denmark
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Anybody know what the Taiwanese OEM 18" drivers are that Nelson mentions?
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Old 1st December 2008, 07:16 AM   #213
dpaws is offline dpaws  United Kingdom
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Quote:
Originally posted by Nelson Pass
Here's the first particle of data, a free air impedance curve of both
drivers. The top curve (@60 Hz) is one driver out of the box, the middle
one is the second driver, and the bottom is that same driver after
a short workout, showing lower Q from slightly broken-in suspension.

Nice consistency between the two.
Many thanks for all your good work Nelson. Mine have arrived safety from Oz (thanks Warwick!) Serials B0001 & B0002! Lahdi!

May I ask...

Has the resonance frequency of your D9nf's changed over the last six months as the suspension softens with use? Are we still the wrong side of 60Hz?

How do you regard the top end performance of the driver - in your opinion does it need a supertweeter (I ask because of the talk from others about using a ribbon above them)

I was rather hoping that this driver would cover either the top or the bottom end on it's own - I'm happy to concede to a two way design but I'd resent the complexity of a three way. I don't intend to try an OB design...

Much obliged
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Old 1st December 2008, 10:06 PM   #214
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Quote:
Originally posted by bvan
Anybody know what the Taiwanese OEM 18" drivers are that Nelson mentions?
I'll see if I can dig them up.
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Old 1st December 2008, 10:10 PM   #215
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Quote:
Originally posted by dpaws
Has the resonance frequency of your D9nf's changed over the last six months as the suspension softens with use? Are we still the wrong side of 60Hz?

How do you regard the top end performance of the driver - in your opinion does it need a supertweeter (I ask because of the talk from others about using a ribbon above them)

I was rather hoping that this driver would cover either the top or the bottom end on it's own - I'm happy to concede to a two way design but I'd resent the complexity of a three way. I don't intend to try an OB design...
Good question - this would be a good time to re-measure them.

I don't find the need for a tweeter on top, but it's certainly true that a fine
tweeter wouldn't hurt. My favorites are the smaller RAAL and the SEAS
Crescendo. I really like the Pioneer ribbons also, but they are no longer
available.

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Old 2nd December 2008, 06:49 AM   #216
dpaws is offline dpaws  United Kingdom
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Quote:
Originally posted by Nelson Pass


Good question - this would be a good time to re-measure them.

That would be great if you don't mind... let me know any costs incurred for a set of results and I'll Paypal - the info is invaluable for my enclosure project who's initial dimensions will be based on parameters.

WRT tweeters, I was looking at the Focal TBe (fantastic small form factor), the 4Pi or the Raidho planar but... how would I correctly position either as I would need almost a concentric mounting at 16kHz...

Would it be better to simply fire them upwards ("ambience style") rather than trying to create a coherent point source?
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Old 2nd December 2008, 07:01 AM   #217
bvan is offline bvan  Denmark
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I'd like to chuck in a tweeter nomination as I think it might be overlooked, the Gemni tweeter as used by Bastanis Audio. A very classy dome IMO, and dipole to boot. Not cheap at $800 though.
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Old 14th December 2008, 07:09 PM   #218
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Quote:
Originally posted by dpaws
Has the resonance frequency of your D9nf's changed over the last six months as the suspension softens with use? Are we still the wrong side of 60Hz?
I re-ran the curves and they did not change significantly. Within the accuracy
of the test (nominal room temperature, etc) the impedance peak is at the
same 64 Hz with a peak value within a few percent.
Attached Images
File Type: gif feastrex d9nf z.gif (11.9 KB, 1000 views)
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Old 14th December 2008, 08:16 PM   #219
dpaws is offline dpaws  United Kingdom
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Many thanks indeed Nelson, not what I wanted to hear but...
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Old 26th May 2009, 07:13 AM   #220
fff0 is offline fff0  Singapore
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Quote:
Originally posted by Nelson Pass
My best full range drivers are the Feastrex D9nf and the Lowther
PM6A (Ticonal Alnico magnet and an overhung silver 16 ohm voice
coil).

....................I can easily recommend either. I do need to spend significantly
more time with both, and time is always in short supply.

Ask me again in a year.

Dear Nelson,

May I ask if there is any progress/ updates going with your toys - full range drivers ?
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