Neodymium or ceramic?

[Titanium Dome]

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]

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!

[louped garouv]

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!

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

[Regis]

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]

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]

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]

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...

basically, if you map out primary use (maybe abuse ) 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]

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]

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!!!!!) 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]

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.


Widget

[Earl K]

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 )

[scott fitlin]

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 )

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.

[Earl K]

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]

- Thanks

- Are you back with your Altecs?

<>

Well yeah, and that too!

But, the neo mag woofers work.

[Steve Schell]

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.