Go Back   Home > Forums > Commercial Sector > Manufacturers > Markaudio

Markaudio Designers and builders of audiophile grade drivers

Reply
 
Thread Tools Search this Thread
Old 11th October 2012, 02:00 PM   #11
mp9 is offline mp9  United States
diyAudio Member
 
Join Date: Jun 2006
Quote:
Originally Posted by DeonC View Post
Hi Mark
I am not asking for a huge hulking alnico slug so that efficiency will skyrocket, but OTOH even a similar sized magnet will up efficiency usefully.
Deon
It would be great if it only takes is a "huge hulking alnico slug" to "skyrocket" driver efficiency or even raise it 2 - 3db over it's ferrite counterpart, and across a usable bandwidth. None of the claimed 95db driver's which measure 95db above 2.5Khz and barely 89db below (hypothetical example for the sake of argument)!
  Reply With Quote
Old 13th October 2012, 07:45 AM   #12
diyAudio Member
 
markaudio's Avatar
 
Join Date: Nov 2008
Hi Guys,
Apologies this post will have to be brief(ish) as I'm preparing to make 3000 drivers which have finished by end of next week.

The main problem with the Alnico/Ferrite debate is lack of knowledge by those who profess (or claim) to be "expert" having never designed/built a magnet/motor-set sub-assembly and integrated it into the power-train of a driver. Much of what is written should be treated with care as rarely are there any references to applied design/production engineering and/or authoritative substantiated reliable research that illustrates any significant benefits between the magnet types. So I advise caution when reading any published articles on this subject unless they've got some serious properly referenced trialled research to back up their statements.

In the meantime, Fig 1. - see pic, illustrates the 3 main components in the Motor set:

A = Front Washer
B = Magnet
C = T Yoke
(Power Train = The moving components: cone, cap, coil, flying leads and suspensions)

The relationships between these components is extremely complex. I wrote an illustrated article on the engineering aspects of what is known as the "motor-Set" for full-range emitters. I'll do my best to make it available in PDF download form before the end of the month.

The magnet is only 1 component of this sub-assembly and cannot be isolated from the other components in terms of its performance. A good driver designer will manipulate the types and composition of these components, focusing on acquiring sufficient stable flux density within the Motor-Set coil run gap; To correctly operate the power-train to a pre-determined performance envelope. In some cases Alnico might be chosen, others Ferrite and so on. Typically, in most instances, Ferrite provides the designer with most needs. So far, I've tested Alnico and Neo on Alpair 6, Alpair 7 and Alpair 10 prototype drivers over a 4 year period with no firm results showing any significant operational advantages over Ferrite on these drivers.

I'll do my best to find time to publish the test results for Alpair 6 using a Neo magnet, as this is the most recent work.

Concluding: I would advise caution when anyone tells you Alnico is the best thing since "sliced audio bread". In some case, Alnico, depending on the design of other components in the Motor-Set; And in motive operational requirements for the driver's power-train; And marketing needs, might be a good choice. But stating that Alnico has some properties that are acoustically beneficial is rather mis-leading, as much depends on the other components. There are so many other variables in play, as to make it near impossible to singularly isolate the benefits of exotic magnet materials.


Hi nicoch58,
I've tidied some of your posts, added the references and links. Let me know if i've missed or made any errors. Feel free to comment further, but please include the reference/link when quoting/siting a source, or make clear which are your personal opinions and what's been copied/sited/referenced - thanks.

Sorry guys, I would love to say a whole lot more (try not to over-complicate) but must crack on. As said, I'll do my best to publish my Motor-set article.

Cheers
Mark.
Attached Images
File Type: jpg fig.1.jpg (138.3 KB, 182 views)

Last edited by markaudio; 13th October 2012 at 08:40 AM.
  Reply With Quote
Old 28th October 2012, 10:17 PM   #13
diyAudio Member
 
nicoch58's Avatar
 
Join Date: Oct 2004
look like Dave Slage have fun with field coils ......
MyEmia scroll down a bit
__________________
Sic58
  Reply With Quote
Old 28th October 2012, 10:35 PM   #14
diyAudio Member
 
Scottmoose's Avatar
 
Join Date: Mar 2005
Location: UK
Quite, although how that is relevant to the AlNiCo magnets under discussion, and the fact that only a procrastinating pelican would assume that bolting an AlNiCo magnet to an existing driver would automatically improve it, is lost on me.
  Reply With Quote
Old 29th October 2012, 12:44 AM   #15
diyAudio Member
 
markaudio's Avatar
 
Join Date: Nov 2008
Hi Guys,
I'll need more time to think how best to present what is a very complex technical issue. There's far too much over-simplication in the Alnico/exotic magnet debate. Yesterday, I spent a couple of hours trawling the net seeing how others have represented their research and/or opinions, overall quite disappointing.

For now, here's some information that will hopefully help guys appreciate the complexity of the situation:

Magnet Classification. You can't simply walk into a professional magnet factory and say "please sell me magnets". The maker is going to ask you a ton of questions:

1 - Ceramic (Sintered Ferrite) has 3 sets of measurement classifications. The Chinese, USA and European class sets. The Chinese class is now the most commonly used. The American set is less used and has a limited classification range. The EU set is used within Europe. The Chinese Ferrite classification consist of 27 different magnet grades.

2 - Alnico. There are 2 production methods, cast (pouring molten material into a mold) and the sintered, powdered material formed into a solid using compression. There are 2 sets of classifications, Chinese and American for the sintered; 5 grades in the American and 15 types in the Chinese. Cast Alnico is more complex with 10 grades in the American and 26 in the Chinese set.

Just in these 2 magnet types, using the most common classification (Chinese) a driver designer can choose from 53 differing grades of magnet, before even considering Neodymium, HAST Neodymium, Neodymium-Iron-Boron and Samarium Cobalt. All have differing: Residual Induction, Coercive Force, Temperature Stability, Magnetic Energy Property, Magnetic Degradation, Stress-load, Shatter and machining properties.

We're talking about only 1 component from a set 3 (T Yoke and Front washer) or 4 should a pole cap is added. Designing a Motor Set is a complex business, has to be done in conjunction with the design of the Power-Train sub assembly. NEITHER sub-assemblies can be isolated from the other and all the operational relationships between individual components has to be formulated, tested and should be measured.

I'll think more on how to further develop my current article which is a "technical" paper to a broader comprehensive read.

Cheers
Mark.

Last edited by markaudio; 29th October 2012 at 01:04 AM.
  Reply With Quote
Old 29th October 2012, 01:23 AM   #16
cotdt is offline cotdt  United States
diyAudio Member
 
Join Date: Oct 2005
Send a message via AIM to cotdt
Mark, I do not think there is a big market for expensive alnico-magnet versions of Alpair drivers. It won't be good business. Great sound at affordable prices is what people want.

I've had some vintage alnico-magnet fullranges off eBay and your ceramic Alpairs sound far better. I don't beleive the alnico hype. Instead, I would like a paper-based version of the Alpair 10.2.
  Reply With Quote
Old 29th October 2012, 02:08 AM   #17
diyAudio Member
 
markaudio's Avatar
 
Join Date: Nov 2008
Quote:
Originally Posted by cotdt View Post
Mark, I do not think there is a big market for expensive alnico-magnet versions of Alpair drivers. It won't be good business. Great sound at affordable prices is what people want.

I've had some vintage alnico-magnet fullranges off eBay and your ceramic Alpairs sound far better. I don't beleive the alnico hype. Instead, I would like a paper-based version of the Alpair 10.2.
Hello Cotdt,
You've rightly focused on an essential (cost) and highlighted a mostly negative issue in the audio-world, that being "Hype". Personally, I'll continue to use my Applied Mech. Eng. experience to evaluate all materials on these criteria:

1- Engineering criteria (design, production and assembly)
2 - Value for money (will a material and/or component perform better given for a given cost)

At this time, given the high cost of exotic magnets like Alnico, as yet, I've not been able to extract an advantageous set of performance values from a Motor-Set using this type of magnet. To be fair, I've only had resources to try 2 grades of Cast and 2 of Sintered. Could there be a "magic" grade? Possibly, but having assessed the performance criteria within the Chinese classifications for Alnico, I've not seen any type that will likely deliver a performance advantage over Ceramic.

As for a Paper Alpair 10, 2 prototypes are currently being tested.

Cheers
Mark.

Last edited by markaudio; 29th October 2012 at 02:54 AM.
  Reply With Quote
Old 29th October 2012, 02:17 AM   #18
diyAudio Member
 
markaudio's Avatar
 
Join Date: Nov 2008
Guys,
1 point to note when buying old or vintage Alnico drivers. Chances are their Motor's will be suffering from degradation. You might need to find a friendly driver maker who can re-magnetize their motors.

Cheers
Mark.
  Reply With Quote
Old 29th October 2012, 03:21 AM   #19
doorman is offline doorman  Canada
diyAudio Member
 
doorman's Avatar
 
Join Date: Jul 2003
Location: Vancouver Isl. B.C.
I will follow your progress re: paper cone 10.2 with great interest.
The 10.2's i currently have, installed in (Dave's design) Mar-Ken boxes, in the context of my system, room &c &c. are special.
Don
  Reply With Quote
Old 29th October 2012, 08:35 AM   #20
diyAudio Member
 
nicoch58's Avatar
 
Join Date: Oct 2004
Thanks Mark ,point take !

@Scott you have fun too ... ;(
Ps that conclusion are only in your mint.
__________________
Sic58

Last edited by nicoch58; 29th October 2012 at 08:40 AM.
  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
Crown MA-12000i / MA-5000i / MA-9000i jack2040 Solid State 4 8th March 2011 01:21 PM
Neodymium magnets vs Ferrite magnets blueae1405 Full Range 56 17th November 2009 08:25 AM
Two 15" late 1950s Vintage Magnavox Woofers with Alnico magnets for sale! WBS Swap Meet 0 23rd February 2009 11:22 PM
possibilty of overcharging batteries?? Dan2 Everything Else 8 15th August 2008 10:52 AM
DIY ribbon tweeters using alnico horseshoe magnets tom1356 Multi-Way 2 24th July 2004 12:44 AM


New To Site? Need Help?

All times are GMT. The time now is 06:04 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