If neodymium is all that great . . . - Page 4 - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 25th March 2005, 05:43 AM   #31
Pallas is offline Pallas  Pakistan
diyAudio Member
 
Join Date: Aug 2004
Location: ATL
Quote:
Originally posted by Pan
The Aura drivers seems to be nice, however compared to the Excel drivers I fail to see the superior performance from these drivers at least by looking at the manufacturers graphs.
I'm not sure what you're getting at, if only because Aura and Seas Excel don't have at all comparable product lines. At least, I don't know of any 1" - 4" wideband Excel drivers that cost $15-$35 or hugely expensive "statement" Excel subwoofers. Nor do I know of any Aura NRT tweeters or 5"-10" "statement" Aura midwoofers.

The closest comparison is the Aura NS8 to the W22, but even there I think the targets for each driver are so different that comparison makes about as much sense as comparing the W22 to that sweet-looking new neo-magnet 8" pro driver from B&C.
  Reply With Quote
Old 25th March 2005, 08:30 AM   #32
sbolin is offline sbolin  Thailand
diyAudio Member
 
Join Date: Sep 2004
Location: Bangkok
Default Re: Re: Re: If neodymium is all that great . . .



Originally, you said this:

Quote:
Originally posted by Bill Fitzpatrick
I was reading that neodymium makes a much better magnet than ceramic in regards to quality sound.

If true, where are all the great woofer/mids with the new magnets? I found one ScanSpeak for $160 but that's it.

A lot of discussion ensued about the relative advantages of neo magnets compared to others, also cost constraints, etc - maybe not an 'answer' but informative. Some examples of speakers that use neo magnets has been given (Adire, Morel, many tweets), but you sort of dismissed them for some reason, though it is an answer to your original question. Next you said this:

Quote:
Originally posted by Bill Fitzpatrick

[snip some comments]

Anyway, I've read a lot of opinions about neo here. I was sorta looking for the facts but, as a friend used to say, oh well.

What 'facts' are you looking for, exactly? Dan Wiggins of Adire added some good info about neo magnets (in particular, look at the text I added bold to):

Quote:
Originally posted by DanWiggins
SH grade neo is typically rated to 150 deg C, but EH grade is good to 200 deg C. Both of which are really overkill; to get the magnet that hot your voice coil is at 200+ deg C, which is well beyond the point at which the glues holding it together will fail. In other words, the voice coil will fall apart well before you thermally demagnetize modern SH+ grade neo.

The old L and M grades weren't too good, as they started losing magnetic force at just 100 deg C, which is within the realm of what high power voice coils can withstand.

Neo is like any other magnet material - it has its strengths and weaknesses. It does offer some significant advantages in motor size (weight and physical dimensions), and typical pot-core neo motors are inherently shielded as well. If those advantages are desireable, then use it. Otherwise it may be lower cost to go with ferrite.

Dan Wiggins
Adire Audio

This seems to be your answer. Any design entails choices and compromises, nothing is perfect. The fact that neo magnets AREN'T used is instructive, as is looking at where they are used (car applications, tweets, A/V, etc). In spite of your unreferenced claims, it may be that neo magnets aren't used that much because their higher cost isn't justified except in specific applications (ie, they don't sound better or they would be used a lot, regardless the cost).

Two other links to peruse:

LDSG Motors
LDSG Magnets

It is pretty clear that the motor is mostly responsible for the sound, magnets clearly of secondary importance.
  Reply With Quote
Old 25th March 2005, 08:47 AM   #33
usekgb is offline usekgb  United States
diyAudio Member
 
usekgb's Avatar
 
Join Date: Feb 2003
Location: Salt Lake City, UT, USA
Default Re: Re: Re: If neodymium is all that great . . .

Quote:
Originally posted by Bill Fitzpatrick


I haven't and couldn't because I couldn't find reference to it via Google. Could you give me a link?


Sorry Bill, I don't have a link for you. This is the driver that JBL uses in many of their new high power PA speakers. This is in their 12" line array, the SRX712M, and their new mini-line. I have a fair amount of experience with JBL's latest Neo drivers, and I am very pleased with them. Sorry I couldn't give you more info.

Cheers,
Zach
__________________
Ahhhhhhhhh...............That's what that button does.
  Reply With Quote
Old 25th March 2005, 12:10 PM   #34
Pan is offline Pan  Sweden
diyAudio Member
 
Join Date: Sep 2002
BF wrote,

"Anyway, I've read a lot of opinions about neo here. I was sorta looking for the facts but, as a friend used to say, oh well."

Im so sorry I contaminated your pure neo-thread. Just tell me to leave with my nonsense and Im out starting my own "no facts only speculations and opinions neo thread".

Or maybe you can lighten up a bit..

/Peter
  Reply With Quote
Old 25th March 2005, 12:16 PM   #35
Pan is offline Pan  Sweden
diyAudio Member
 
Join Date: Sep 2002
Quote:
Originally posted by Pallas


I'm not sure what you're getting at, if only because Aura and Seas Excel don't have at all comparable product lines. At least, I don't know of any 1" - 4" wideband Excel drivers that cost $15-$35 or hugely expensive "statement" Excel subwoofers. Nor do I know of any Aura NRT tweeters or 5"-10" "statement" Aura midwoofers.

The closest comparison is the Aura NS8 to the W22, but even there I think the targets for each driver are so different that comparison makes about as much sense as comparing the W22 to that sweet-looking new neo-magnet 8" pro driver from B&C.
As far as I know there are a 10" Aura woofer and also a 10" Excel woofer. If you look at the graphs published at the companys homepage youll see that the performance are not superior on the Aura woofer. Even the W22 has better upper bass than the Aura woofers. I also said "withing physicall limits" meaning that obviously the 18" Aura has less distortion than the W26 at high spl when W26 run out of excursion.

However for many listeners the performance at low to medium spl is what counts and (again) judging by the manufactureres measurements there are no superior perofrmance from the UH neo approach in this case.

Please also take my other points about other drivers into consideration.

Now, was it so hard to understand really?

By a quick glance on the web there is nothing that indicates a neo based motor as being inherently better than a ferrite dito.

/Peter
  Reply With Quote
Old 25th March 2005, 01:03 PM   #36
MBK is offline MBK  Singapore
diyAudio Member
 
Join Date: Apr 2002
Location: Singapore
Maybe I miss something but... the original issue discussed resolution performance. Can anyone deduct resolution performance (and dynamic compression etc) from frequency response graphs and manufacturer's spec sheets alone? I don't think so - different Q's, some peaks here and there etc., will be addressed by the eventual speaker designer but say nothing much about resolution and transparency. They only tell you how to use the driver in a speaker. The power of the engine and the size of the brakes tell you nothing about a car's handling.

Manufacturer's specs usually include neither linear distortion / energy storage data (important for transparency), nor dynamic compression data, nor resolution data. In fact you're lucky if you get THD data. So I really can't imagine how to judge on these parameters from (mostly in all likelihood) a single on-axis FR graph.
  Reply With Quote
Old 25th March 2005, 01:07 PM   #37
diyAudio Member
 
Join Date: Jan 2003
Location: Zurich
Quote:
Originally posted by thoriated
Actually, Alnico is the least susceptible of the magnetic materials I have listed to flux modulation.
Dan was refering to permanent demagnitization, not AC flux modulation. Alnico is resistant to flux modulation so long as the current through the voice coil is within a certain range, but go beyond that range and you get permanent demagnitization...well permanent is not the right word exactly, you lose magnetization until you put the driver in a magnetizer and give it a good zap. If you've got a vintage alnico driver, chances are it could do with a zap.

John
  Reply With Quote
Old 25th March 2005, 01:42 PM   #38
Pan is offline Pan  Sweden
diyAudio Member
 
Join Date: Sep 2002
MBK,

Yes I think you missed some things.

"the original issue discussed resolution performance."

Resolution and distortion is related dont you think?


"Can anyone deduct resolution performance (and dynamic compression etc) from frequency response graphs and manufacturer's spec sheets alone?"


I dont thihnk anyone ever claimed that but to some degree yes, if the measuremetns are good and detailed enough. Resolution needs low HD/ID distortion, flat FR and fast decay.


"So I really can't imagine how to judge on these parameters from (mostly in all likelihood) a single on-axis FR graph."

Neither can I and no one ever claimed they could.


/Peter
  Reply With Quote
Old 25th March 2005, 02:37 PM   #39
diyAudio Member
 
Join Date: Apr 2003
Location: NY
Hello Bill,

these issues have ensued discussions on this forum before, here is the link:

Best Sounding Magnet!

Cheers
__________________
RB
  Reply With Quote
Old 25th March 2005, 02:43 PM   #40
diyAudio Member
 
Join Date: Aug 2002
Location: Seattle or Shanghai
thoriated posted:
Quote:
Actually, Alnico is the least susceptible of the magnetic materials I have listed to flux modulation. The table makes clear that while Alnico is probably not what you want to place your bets on for high SPL stadium installations, it is still well ahead of neodymium and totally outclasses ceramic for the highest performance sound quality applications where knuckle dragging abuse is not part of the sonic equation.
Hmmm... The coercive force is what indicates resistance to demagnetization. Typical AlNiCo is in the 1200-1900 range. Ferrite is 3500-4500. Neo is 12,000-14,000. AlNiCo is a lot easier to demagnetize than neo or ferrite. I know we run a LOT lower charging voltages when demagnetizing AlNiCo magnets.

There's a pretty good paper on magnets at Arnold Magnetics where they even point out that the coercive force of AlNiCo is low, meaning it is susceptible to demagnetization:

http://www.arnoldmagnetics.com/mtc/pdf/TN_0205.pdf

tomtt posted:
I think Ragnar was referring to the electrical conductivity of the magnet itself working as a shorting ring. Ceramics (ferrites) are much worse than neo or AlNiCo in this area! Typical N40 grade neo is around 700 kS/m, while AlNiCo 6 is ~3 times that (around 2.2 MS/m). Ceramics are much worse, down around 60 kS/m.

Of course, steel is typically about as good ast AlNiCo itself (~2 MS/m) and copper (~60 MS/m) or aluminum (~35 MS/m) are really the way to go for shorting rings.

If you're relying on your magnet to make your shorting ring, it's really not a good thing - there are MUCH better ways to go, since even the "best" magnet from an electrical conductivity standpoint is about equal to the steel in your motor.

hancock posted:
Quote:
Dan was refering to permanent demagnitization, not AC flux modulation. Alnico is resistant to flux modulation so long as the current through the voice coil is within a certain range, but go beyond that range and you get permanent demagnitization...well permanent is not the right word exactly, you lose magnetization until you put the driver in a magnetizer and give it a good zap. If you've got a vintage alnico driver, chances are it could do with a zap.
Bingo. Ferrite will start to bend a bit earlier than AlNiCo, but you can't get it fully over without toasting the voice coil. AlNiCo, on the other hand, holds up fairly well but push it just a bit to far and it's gone.

And of course the amount of magnet volume will also affect the coercive force - how well the magnet resists demagnetization. Volumetrically, AlNiCo is pretty good against ferrite, because you get much more force from a given volume of AlNiCo (or Neo) as compared to ferrite. Of course, if you're talking flux output, then we typically need 10X the volume of ferrite, and that really equalizes the way the magnets resist flux modulation.

Dan Wiggins
Adire Audio
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
neodymium speakers ? rmsaudio Multi-Way 32 6th July 2012 08:41 AM
Neodymium magnets NickC Full Range 1 19th May 2008 09:41 PM
FS Gainclone Great Chassis, Potted toroidal, great sound PHilgeman Swap Meet 4 2nd May 2006 01:20 PM
Neodymium Magnets Frazzled Everything Else 4 25th July 2004 05:42 PM
Neodymium is now Mainstream? Variac Multi-Way 12 19th March 2003 11:55 AM


New To Site? Need Help?

All times are GMT. The time now is 08:20 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2