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Old 26th June 2008, 10:44 PM   #21
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Quote:
Originally posted by agent.5


What would you want a 10db rising pattern?
It's the classic response of a driver meant for horn loading.
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Old 26th June 2008, 11:26 PM   #22
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Quote:
Originally posted by LineSource
Commercial customers might also demand the 120 db to meet marketing demands.

Increasing the efficiency will reduce continuous power requirements.

I snipped a bit but basically this driver would be designed more for home/studio use. Commercial customers would have other choices from our catalog that would better suit their needs. Also this driver will be available in the current ceramic, or the upcoming Alnico or Field coil motors. We are serious in that most all of our product line will have the other motor options once they are released.


Quote:
Originally posted by agent.5
probably just a few watts, as most will probably use a SET amp.

The coil will handle quite a bit as it will have all the heatsinking of the standard TD motor. I don't see a problem with even 100W for this one. Now 1KW would be another story.


Quote:
Originally posted by swak
I am happy to see more of us are thinking about a similar setup and that AE speakers can come up with great drivers.

Nick:

What would the approx. price increase for a field coil motor be?

John

AE speakers could offer a kit or a completed design for DIYers that wouldn't like to mess with all the design complications or don't have the technical background. I think that would certainly help selling the drivers. An 18sound XT120 horn with a CD could cover the range above the two (midbass, bass) AE drivers, with the option of a supertweeter for the range above 12K.


PS: I would like to add that it could be very interesting for some if there would be drivers designed specifically for current drive amplifiers. Thorsten (Kuei) gave some points on this forum on needed motor/driver properties and advantages of current driven speakers versus traditional voltage drive, he even sketched a system with Seas drivers.

I don't know what the field coil will cost, a lot will depend on the massive coil of wire needed and the pricing of copper when we go to production. Figure $100 to $200 extra over a regular TD I would imagine.

Design kits are on the stove as well, I talk with John most every day on this part especially with respect to getting mids and tweeters sorted out that can keep up.

What would be different in a driver designed for current drive?


Quote:
Originally posted by tinitus
67hz Fs, 100db, double 6ohm voicecoil, stiff surround, dipole, compression driver, waveguide ... now I am so confused I dont know what to say

That is what happens when a couple of driver engineer's can hand build whatever they can dream up. Our design is modular and based on a couple motors and the same baskets, we can mix and match multiple parts to suit the target spec. We just need to know what specs to shoot for
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Old 26th June 2008, 11:43 PM   #23
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Well, the small fullranges that many people like to use in OB are mostly around 90db, some of the bigger ones a bit more

A 12" with 93db, Qts 0.65 and Fs 25hz ... accordian surround is a good idea ... subs not needed

Thats my bet on a possibly popular driver
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Old 27th June 2008, 12:30 AM   #24
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Question is whether they would pay the exstra dollars to get a quality driver, as many high Qts drivers come really cheap

if not your customers could very well be the hard core guys that use expencive high sensitive FR drivers, totally different ballgame ... here there may be a relatively good market fore a 15" with field coil

So it boils down to a cheapish 12" and an expencive 15"
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Old 27th June 2008, 12:56 AM   #25
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Quote:
Originally posted by John_E_Janowitz
... in your model are you assuming the same size ndFeB+37 as the ceramic 5? If so, this is an extremely expensive piece of neo to start with. There are 2, maybe 3 magnetizers in all of the US that can magnetize a piece of neo this large.
John

John,

In my 2D model, a 0.85" thick (what I measured on my speaker) Ceramic magnet generated 0.18 T in the center of the gap, and a 0.25" thick NdFeB_37 ring generated 0.37 T in the center of the gap. Have you measured the gap flux in a TD15 dipole?

From product pictures, some speaker manufactures use full NdFeB rings, while other use arcs and multiple small circular disks.

For the highest efficiency underhung midrange motor, NdFeB might be worth a prototype test, even with a pre-magnetized ring. If NdFeB saturates the pole steel, a field coil with all of its cost and power supply issues should not yield higher efficiency. Stop global warming with high efficiency NdFeB! :-)


"The huge ring type of sintered Rare earth ndfeb magnets magnets
Key Specifications/Special Features:
1.The most large Ring type magnets, such as F88F3015 mm, F125F5030 mm;
2.The Magnets with high grade material, such as N35SH,N38SH,N40H,N42H;
3.The Magnets be used in the lines of speaker and motor."
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Old 27th June 2008, 01:21 AM   #26
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Some max SPL vs. Xmax data comparing 10" and 12" dipole midranges on 24" x 48" baffle, with speaker mounted at 36" from floor.

10" = 345 cm2
12" = 530 cm2

FOR 80 Hz
110 db SPL @ 1M
10" = 8.7mm Xmax
12" = 5.6mm Xmax

FOR 120 Hz
110 db SPL @ 1M
10" = 2.6mm Xmax
12" = 1.7mm Xmax

========================

FOR 80 Hz
115 db SPL @ 1M
10" = 15.4mm Xmax
12" = 10.0mm Xmax

FOR 120 Hz
115 db SPL @ 1M
10" = 4.6mm Xmax
12" = 3.0mm Xmax
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Old 27th June 2008, 01:37 AM   #27
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We are not set up for large neo motors at the moment. Cost is a primary concern as this is a low production design we are talking about here. This midbass if done needs to use as much as possible that is currently on the shelf, and it will be able to use the planned Alnico and Field Coil motors. We can revisit the neo question in the future once we gear up for it, but it will be awhile as it will be a larger investment than anything else done yet by either Lambda or AE.
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Old 27th June 2008, 03:44 PM   #28
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Quote:
Originally posted by LineSource

For the highest efficiency underhung midrange motor, NdFeB might be worth a prototype test, even with a pre-magnetized ring. If NdFeB saturates the pole steel, a field coil with all of its cost and power supply issues should not yield higher efficiency. Stop global warming with high efficiency NdFeB! :-)
While an underhung motor is a good example where more B is often useful or desired, be cautious in blindly chasing motor strength in the name of efficiency.

The driver Sd and minimum achievable moving mass set practical limits on what sort of efficiency is possible, especially below some lower frequency. Depending on the minimum mass threshold, that could be in the 300-500Hz range. More BL on the same coil will give you a greater calculated sensitivity, but only at higher frequencies, and in an open baffle or sealed design, the increasing motor strength will in fact lower the sensitivity below this effective hinge point.

Moral of the story: Before you start chasing any given parameter or quality be sure to check the ideal thresholds of what is possible. If you want high efficiency (~100dB @ 1W/1m) in an open baffle, you either will have to limit your low frequency expectations or use larger Sd than a single 10" driver through multiples or larger cones.
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Old 27th June 2008, 04:13 PM   #29
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Nick,

I followed the discussions of current source amps some years ago on this forum and have read Hawksforth's papers on the topic. The advantages are considerable less compression and distortion. I am by far not an expert on driver design, but perhaps you can have important pointers on the following thread: Current Driven Loudspeakers and Tranconductance Amplifiers , look for Thorsten's (a.k.a. Kuei Yang Wang) posts.

Have you considered H- or W-frame and "unipole" "subs" for the lowest freq range of the kits? Ferekidis (you will find some papers on the web) and Kempe have some very interesting investigations concerning maximal baffle width and comparisons between Dipole, Monopole and Unipole, favoring the latter by reasons shown in the papers. I don't know if it would work, but at first glance one could arrive at a unipole sub using little damping on the back of the cone (like aperiodic) and current drive. A unipole commercial version is the Gaithain RL901K ( http://www.wvier.de/texte/Monopol,%2...&%20Unipol.pdf ). Their papers are in German, perhaps in English through AES. If you need a translation I could help.
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Old 27th June 2008, 04:13 PM   #30
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Default system & market view . .

Hi Nick

What about aiming for synergy in designs with this sort of similarly high quality & sensitivity tweeter, crossed at c 1600 Hz
http://www.raalribbon.com/products_flatfoil_140-15.htm

RAAL are fwiw liked by (to some degree) Lynn Olson and a number of others

If the Lambda midbass can be just 95 dB/ watt, that'll allow most tube amps. A good SS amp would have dynamics to burn.

Allow the bottom Hz to be the balancing factor, probably (baffle/ box dependent) in the range 100 – 150 Hz. Below that a sub

So 95 dB, 150 – 2000 Hz

By lowering the sensitivity factor to 95 dB, for sound quality better than the JBL 2123 or PHL 3451 or Eighteensound – ie "best in breed"

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