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scott fitlin
07-13-2005, 01:01 PM
I have been reserching 15in woofers, everyone makes them now with neodymium magnets! JBL, as well as others! There are a few different models, including JBL, that interest me.

My question for today is neo,s reliability! A few guys I have spoken to, sound contractors, have told me to stay away from neodymium magnet woofers because the magnets have a habit of becoming completely discharged if overheated! I knew this was in fact a problem with neo several years ago, and neo was only really used for compression drivers etc! But now every manufacturer has seemingly high performance, and lightweight woofer models available featuring neo magnets, so whats the real deal? Is neo a reliable magnet in a high power woofer, in commercial use?

An enquiring mind needs to know! :)

Titanium Dome
07-13-2005, 02:35 PM
My...name...is...Neo!


Many of the issues have been addressed, but a neo magnet still has its inherent virtures and vices.

Here's what one manufacturer has to say about it and why his design modifications make it a great magnet.

http://www.euphonicaudio.com/2005/technology/neo_magnets.htm

You can also check out the Gaussboys general warning about neos, including what heat and fracturing can do.

http://www.gaussboys.com/warnings.php

I always find musicians' discussion on these kinds of topics enlightening, if anecdotal, so you might enjoy this:

http://www.musicplayer.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=5;t=011558;p=1

A brilliantly executed neo magnet is a remarkable thing, i,e,, heat sinks, liquid cooling, thermal dissipation casings, etc.

Mr. Widget
07-13-2005, 02:46 PM
I am not sure if this is relevant, but I had a mishap with an imported compression driver with a neodymium magnet and it could not be repaired since no one here had a magnetizer powerful enough to recharge the magnet once the repair was complete. I believe one of our European members had a similar problem with a JBL neodymium compression driver and was told that it must go back to the factory for repairs.

I would assume the woofers would have the same issues.

Widget

scott fitlin
07-13-2005, 03:06 PM
Thank you, Dome, good reading! I am aware there will be sonic differences between ceramics and neo,s, and its interesting to note that some find the mids of neos somewhat brittle sounding! I have no idea, I havent, as of yet, auditioned any myself! I was surprised that two different sound guys told me to stay away from neo,s! I know about the Aurasound 18 back in the 90,s, demagnetizing from extreme use, especially if they were blown, but would have thought since most manufacturers offer this as a regular product in their respective lineups these days, the heat issues have been solved!

Keep it comin, seems from the little bit Im reading, heat IS still an issue!

scott fitlin
07-13-2005, 03:07 PM
I am not sure if this is relevant, but I had a mishap with an imported compression driver with a neodymium magnet and it could not be repaired since no one here had a magnetizer powerful enough to recharge the magnet once the repair was complete. I believe one of our European members had a similar problem with a JBL neodymium compression driver and was told that it must go back to the factory for repairs.

I would assume the woofers would have the same issues.

WidgetWell, then serviceability becomes an issue should the magnet be discharged! And, yes it is relevant, as it has to do with reliability!

Thank you!

pelly3s
07-13-2005, 04:16 PM
I use Neo drivers in a lot of my boxes at work, all my monitors have 2255's and my double 18s are 2258's. I also use some EV Ndym 6 horns and I havent had any issues. As was mentioned though the magnetizer that we have wont even touch them. Im telling you I would rather take the chances then break my back moving the double 18s. Just my personal opinion. I know there are a lot of people out there who dont like them but i havent had any issues yet

scott fitlin
07-13-2005, 04:30 PM
As I said, the neo woofers i am looking at are very interesting! Thus far, two sound contractors have told me to stay away from them! Thats why I am asking questions. OTOH, since Dome turned me on to talkbass.com, I have found some more interesting reading from the musicians! I feel bass guitarists put their woofers through more abusive use, than playback audio apps! So if they can withstand the rigors of live, uncompressed, sometimes highly distorted bass, they can withstand pre recorded music!

As to their sound? Well Im just gonna have to order two drivers and see for myself what they do or dont do!

But heres another interesting read > http://www.talkbass.com/forum/showthread.php?t=167954

The one thing I seem to have come across is they, ( neos ), do have a midrange bump! Some like, some dont, and this may account for the brittle sound some claim they have!

:)

Tom Loizeaux
07-13-2005, 04:54 PM
JBL uses Neo magnets not only on their high end audiophile speakers (K2 Series) but also in their HLA and VerTec line array systems. Both the HLA and VerTecs are considered "high end" in sound reinforcement circles. They do sound very good, are relatively light, buy they are expensive! These systems are moved around for each job, so weight is a major concern. Though time will tell, I believe Neo magnets are going to be the material used in the coming years.

Tom

scott fitlin
07-13-2005, 04:59 PM
JBL uses Neo magnets not only on their high end audiophile speakers (K2 Series) but also in their HLA and VerTec line array systems. Both the HLA and VerTecs are considered "high end" in sound reinforcement circles. They do sound very good, are relatively light, buy they are expensive! These systems are moved around for each job, so weight is a major concern. Though time will tell, I believe Neo magnets are going to be the material used in the coming years.

TomNeodymium is the magnet material of the future! Weight being the primary reason! The woofers Im looking at being good for horn loading, are only 10lbs each! Installation would be a walk in the park!

scott fitlin
07-13-2005, 06:44 PM
I use Neo drivers in a lot of my boxes at work, all my monitors have 2255's and my double 18s are 2258's. I also use some EV Ndym 6 horns and I havent had any issues. As was mentioned though the magnetizer that we have wont even touch them. Im telling you I would rather take the chances then break my back moving the double 18s. Just my personal opinion. I know there are a lot of people out there who dont like them but i havent had any issues yetBesides the lighter weight, whats your opinion of neo magnet woofers sound compared to the more traditional ceramics? Or at least can you compare the sound of the neos your currently using, to the drivers they replaced?

speakerdave
07-13-2005, 06:47 PM
Member Geiger points out on another thread that the number one concern in engineering a new product is to minimize warrantee returns. Unless we think JBL technical staff is walking off a cliff like grunion, it's a safe chance that neodymium magnets will continue to function under normal use within application.

I'm puzzled by this idea that the frame can be made light because the magnet weighs less. I always thought it was the force exerted by the motor on the cone (and air) that required the rigidity of the cast frame. It seem to me that with a less massy motor a MORE rigid frame would be necessary. Any physicists around?

David

Mr. Widget
07-13-2005, 07:05 PM
I'm puzzled by this idea that the frame can be made light because the magnet weighs less... Any phycisists around?


I guess it is physics in the Newtonian sense.

The greatest physical stresses on the drivers come from transportation. Think about a 10-15 lbs magnet structure cantalevered off of the back of a driver frame.... a few good bounces will show you what angular momentum is all about.:)

Widget

pelly3s
07-13-2005, 07:09 PM
scott they sound better than any of the other JBLs i've used. I would use EVX 180s but i couldnt move them but thats because i love the sound of the 180s. The subs I use are internally the same size as a 4880 and the 2258s have really been the only ones in those boxes. they are a very accurate speaker and they are very efficient for what they are

speakerdave
07-13-2005, 07:33 PM
The greatest physical stresses on the drivers come from transportation. Think about a 10-15 lbs magnet structure cantalevered off of the back of a driver frame.... a few good bounces will show you what angular momentum is all about.

Oh, right! UPS and roadies!

Thanks,

David

scott fitlin
07-13-2005, 09:41 PM
JBL uses Neo magnets not only on their high end audiophile speakers (K2 Series) but also in their HLA and VerTec line array systems. Both the HLA and VerTecs are considered "high end" in sound reinforcement circles. They do sound very good, are relatively light, buy they are expensive! These systems are moved around for each job, so weight is a major concern. Though time will tell, I believe Neo magnets are going to be the material used in the coming years.

TomThe JBL neos are VERY expensive! But the European speaker companies neos are less expensive than their ceramics, and even less expensive than JBL ceramics!

Theres another Italian manufacturer named Ciare, some of the Pros are liking this brand alot, and they are really inexpensive, neo and all! B & C,s neos are cheaper than their ceramics, go figure!

Is raw neodymium cheaper on the other continent? :blink:

Mr. Widget
07-13-2005, 10:31 PM
The JBL neos are VERY expensive! But the European speaker companies neos are less expensive than their ceramics...I'm not sure how much the magnet material costs affect the driver prices.

TAD TD4001 Alnico $1850
TAD TD4002 Neodymium $1490
TAD TD4003 Neodymium $2300

All three compression drivers use 4" beryllium diaphragms. Ferrite is only used in their least expensive woofers.

Widget

57BELAIRE
07-14-2005, 07:32 AM
Member Geiger points out on another thread that the number one concern in engineering a new product is to minimize warrantee returns. Unless we think JBL technical staff is walking off a cliff like grunion, it's a safe chance that neodymium magnets will continue to function under normal use within application.

I'm puzzled by this idea that the frame can be made light because the magnet weighs less. I always thought it was the force exerted by the motor on the cone (and air) that required the rigidity of the cast frame. It seem to me that with a less massy motor a MORE rigid frame would be necessary. Any physicists around?

David

David....while not a physicist, I am a naturalist and I think the animal you are referring to is the lemming...the grunion is a fish.;)

speakerdave
07-14-2005, 07:55 AM
These were GRUNION. I SAW them!

David ;)

57BELAIRE
07-14-2005, 08:02 AM
These were GRUNION. I SAW them!

David
:thmbsup: :cheers: I'll have what he's having!

B&KMan
07-14-2005, 09:32 AM
I'm not sure how much the magnet material costs affect the driver prices.

TAD TD4001 Alnico $1850
TAD TD4002 Neodymium $1490
TAD TD4003 Neodymium $2300

Widget

Well, Maybe add my 2 cents info...

Mr. Hiraga explain in book (speakers) the type of magnet and difference of each ...

Ex: alnico is not precise appelation... because is exist few types of alnico...

The old jbl is make with alnico 5 and tad with alnico 7...

The particularity of alnico is response distortion on 3, 5, and 7, harmonics... the gauss is identical of each other type but ... the ferrite is create more distortion, the ceramic too, the neodynium is really better but alnico is the best... but fragile of heat and demagnetisation in time...

this is the reason of the old driver is most wanted by audiophile in asie and europe... Of course the alnico is relatively fragile and is not really reliable for heavy cormmercial work...

Now, because acess and the power of neodynium is more easy and because this type of magnet is more small and because the technology now permit to cooling better efficiently this type, the most cie prefer "Neo" to "Al's"

if you look GOTO (probably the top crazy cie of horn driver) all is alnico...
check the motor of bass horn !! over 200 lbs pound alnico magnet !!!
(the price of house)

:cheers:

scott fitlin
07-14-2005, 03:28 PM
I ordered a pair of neo magnet woofers, they are very efficient, and very suitable for horn loading, and I ordered a pair of ceramics, also very suitable for basshorns!

Both woofers have wide frequency response, very high EBP,s and BL factor, I will install, power them correctly, and listen!

Time will tell! :)

edgewound
07-14-2005, 04:32 PM
I guess it is physics in the Newtonian sense.

The greatest physical stresses on the drivers come from transportation. Think about a 10-15 lbs magnet structure cantalevered off of the back of a driver frame.... a few good bounces will show you what angular momentum is all about.:)

Widget

Not to mention leverage

scott fitlin
07-18-2005, 08:54 AM
My neos arrived today! They are soooooooooo light! I will install later tonight, and see what they do, but they are so light, its almost too light, doesnt feel like a woofer, at least as I know em! LOL!

B&KMan
07-18-2005, 09:37 AM
:applaud:

The driver is look same ???

Do you have pict??

and what your first impression sound ???

:cheers:

scott fitlin
07-18-2005, 09:41 AM
From the woofers cone and frame it looks like any other woofer! The magnet is MUCH smaller, and much lighter! When you pick it up it ways just a bit more than a JBL tweeter!

Impressions of sound? Dont know yet! Have to install later this evening after I close for the day! I will have something to say, you can count on it!

I am eager to hear them, though! :D

Mr. Widget
07-18-2005, 10:25 AM
Don't forget to break them in before tossing them back....


Widget

scott fitlin
07-18-2005, 10:34 AM
Don't forget to break them in before tossing them back....


WidgetThey look nice! I mean they are so light, its gonna be really easy to install, as compared to another woofer Im trying which weighs 26lbs!

But Ill do my best to do as you ask, Widget!

:applaud:

johnaec
07-18-2005, 04:34 PM
Scott - what models did you end up getting?

John

scott fitlin
07-18-2005, 04:52 PM
Scott - what models did you end up getting?

JohnIm trying out some B & C woofers, both models are very suitable for horn loading! The neo is the higher efficiency, with higher midband sensitivity!

I am trying the B & C-15PL100 and the B & C-15NDL76!

And WidgetWorks is custom making exceptionally well built ported subs for me, most likely to be used with the JBL-2242!

This is part of my modernization of my system! Amps, speakers, electronics!

stevem
07-24-2005, 07:34 AM
From the woofers cone and frame it looks like any other woofer! The magnet is MUCH smaller, and much lighter! When you pick it up it ways just a bit more than a JBL tweeter!

Impressions of sound? Dont know yet! Have to install later this evening after I close for the day! I will have something to say, you can count on it!

I am eager to hear them, though! :D

Scott, did you ever get these woofers up and running? Have you posted your evaluation of their sound yet? I'd really like to know what you think of the sound of the neo woofers as compared to the ferrites.

Titanium Dome
07-25-2005, 08:22 AM
Scott, did you ever get these woofers up and running? Have you posted your evaluation of their sound yet? I'd really like to know what you think of the sound of the neo woofers as compared to the ferrites.

Yes, inquiring minds want to know.

scott fitlin
07-25-2005, 09:39 AM
Ill post a well thought out opinion later today! Been super busy this weekend, and havent really been paying attention!

Get out of here at 4:30AM, get home its 5:10AM, sleep till 9:30AM, get up and come back all over again! Im not in critical listening mode, yet!

:snore:

louped garouv
07-27-2005, 08:36 PM
Ill post a well thought out opinion later today! Been super busy this weekend, and havent really been paying attention!

Get out of here at 4:30AM, get home its 5:10AM, sleep till 9:30AM, get up and come back all over again! Im not in critical listening mode, yet!

:snore:

at least you have good toys to play with at work...... I get to be a spreadsheet jockey from 8-5..... :(

Regis
07-28-2005, 08:13 AM
at least you have good toys to play with at work...... I get to be a spreadsheet jockey from 8-5..... :(


You too? I crunch numbers all day long and mostly used Excel, but now I'm hooked on MS Access. Especially if you have 30,000+ line databases! The Access queries just make it magic and then Excel puts the polish to the finished analysis, via Pivot charts.

louped garouv
07-28-2005, 08:17 AM
You too? I crunch numbers all day long and mostly used Excel, but now I'm hooked on MS Access. Especially if you have 30,000+ line databases! The Access queries just make it magic and then Excel puts the polish to the finished analysis, via Pivot charts.

I agree that the database option is much much better, but I work for an organization with fairly antiquated systems (make that really antiquated -- mainframes written in COBAL); but we are supposedly migrating to SAP within the next few years.......

Hopefully I will have my CPA and have moved on by then.... ;)

Don McRitchie
07-29-2005, 07:14 PM
I have some general comments about magnets as a result of some of the issues raised above. Threre are two main characteristics of magnets that affect loudspeaker performance: flux modulation and temperature losses. Each characteristic has a range in which degradation is reversable, and a point beyond which degradation is irreversable. With regards to flux modulation in the reversible range, the main magnet types rank as follows from best to worst:

1) Alnico
2) Neodymium
3) Ferrite

When ranking the threshold at which flux modulation leads to permanent energy losses, the order changes to:

1) Neodymium
2) Ferrite
3) Alnico

With regards to termperature performance in the reversible range, magnet types rank as follows:

1) Alnico
2) Neodymium
3) Ferrite

When ranking the threshold at which temperature leads to permanent energy losses, the order changes to:

1) Alnico
2) Ferrite
3) Neodymium

As you can see, no one magnet type performs best under all conditions. Now factor in cost, energy by weight and ease of fabrication and you can see that a loudspeaker designer has numerous variables that dictate different choices depending on application.

As I have said many times, none of the deficiencies above are absolute and you can manage or improve performance for each material through engineering choices in application. Obviously, this carries a cost constraint.

With regards to the temperature issue that started this thread, Neodymium magnets most definitely can be permanently damaged at temperatures as low as 300 degrees F (far lower than Alnico or ferrite). That is why JBL goes to such great lengths to heat sink and convectively cool neo drivers. This works so effectively, that the last time I talked to JBLPro they had seen less than one dozen driver returns with temperature damaged drivers out of the tens of thousands of neo drivers they have made.

louped garouv
07-29-2005, 07:22 PM
OMG -- some of you all are like a walking tech manuals..... Seriously, thanks for sharing, I learn so much through great forums like this....

but thanks for the words in no uncertain terms for those of us who are a bit thick... :D

basically, if you map out primary use (maybe abuse :scold: ) patterns... it is more likely that you will be happy with your driver selection long term..... and you may be able to do things more cost effectively based on the driver selection as well???

aust-ted
08-13-2005, 04:35 AM
I have some general comments about magnets as a result of some of the issues raised above. Threre are two main characteristics of magnets that affect loudspeaker performance: flux modulation and temperature losses. Each characteristic has a range in which degradation is reversable, and a point beyond which degradation is irreversable. With regards to flux modulation in the reversible range, the main magnet types rank as follows from best to worst:

1) Alnico
2) Neodymium
3) Ferrite

When ranking the threshold at which flux modulation leads to permanent energy losses, the order changes to:

1) Neodymium
2) Ferrite
3) Alnico

With regards to termperature performance in the reversible range, magnet types rank as follows:

1) Alnico
2) Neodymium
3) Ferrite

When ranking the threshold at which temperature leads to permanent energy losses, the order changes to:

1) Alnico
2) Ferrite
3) Neodymium

As you can see, no one magnet type performs best under all conditions. Now factor in cost, energy by weight and ease of fabrication and you can see that a loudspeaker designer has numerous variables that dictate different choices depending on application.

As I have said many times, none of the deficiencies above are absolute and you can manage or improve performance for each material through engineering choices in application. Obviously, this carries a cost constraint.

With regards to the temperature issue that started this thread, Neodymium magnets most definitely can be permanently damaged at temperatures as low as 300 degrees F (far lower than Alnico or ferrite). That is why JBL goes to such great lengths to heat sink and convectively cool neo drivers. This works so effectively, that the last time I talked to JBLPro they had seen less than one dozen driver returns with temperature damaged drivers out of the tens of thousands of neo drivers they have made.

Don, I have read this post belately. Great stuff. Thanks

I recommend this post be appended to Don's classic "The Great Alnico/ Ferrite Debate" in the technical reference section. I often refer this to anyone asking me about ferrite v alnico.

Regards
Ted

pde2000
04-03-2006, 03:24 AM
nobody's mentioned the alternative of field coil drivers..
the japanese are so hooked on these, pay megabucks and are even making new from scratch (shindolabs). is there something in their argument that only a field coil can provide the required linearity to resolve detail at volume (something like electrostatics having a powerfull HT supply). maybe the future is superconducting (liquid nitrogen cooled!!!!!):barf: please im trying to make a serious point, ive been dreaming about this for 20 years, but then i am a bit crazy (got an A in physics Alevel (high school) then went and wasted a year at medical school).

Mr. Widget
04-03-2006, 10:43 AM
nobody's mentioned the alternative of field coil drivers..
the japanese are so hooked on these, pay megabucks and are even making new from scratch (shindolabs).Our own Steve Schell is also in the process of making contemporary field coil drivers... they aren't dead, just esoteric.:D


Widget

Earl K
04-03-2006, 11:21 AM
Scott,

What were your results from this neo-woof test run ?

( I missed all this previous banter since I was offline all of last summer ) :p

scott fitlin
04-03-2006, 12:21 PM
Scott,

What were your results from this neo-woof test run ?

( I missed all this previous banter since I was offline all of last summer ) :pVERY efficient, and very midrangey. I, after a while, got tired of the amount of mids, but the woofers play clean, and of course, loading 10lb woofers, well, I couldnt complain! The weight reduction is nice.

Earl K
04-03-2006, 01:21 PM
VERY efficient, and very midrangey. I, after a while, got tired of the amount of mids, but the woofers play clean, and of course, loading 10lb woofers, well, I couldnt complain! The weight reduction is nice.

- Thanks

- Are you back with your Altecs?

<> :)

scott fitlin
04-03-2006, 05:34 PM
- Thanks

- Are you back with your Altecs?

<> :)Well yeah, and that too!

But, the neo mag woofers work.

Steve Schell
04-04-2006, 02:24 PM
Thanks for the mention, Mr. Widget. It has been great fun developing our drivers, which are based on the 1930s RCA phenolic cone compression driver. Lately we've been getting good response to 16kHz. with some tweaks to the diaphragms and voice coils. They can be used as low as 200Hz. as well, so the bandwidth is pretty wide.