What constitues a MI Driver

[tinnitus]

I've searched though I'm not sure enough but I just can't find the answer. MI drivers are made for music production and not really for music reproduction.

1) The magnet structure and frame are essentually the same. E-1XX reconed to a 22XX.
2) I assume a spider is a spider is a spider
3) Cone materials are basically the same. Paper or treated paper.
4) That leaves voice coil. Different windings?
5) I guess I forgot that ringing metal dust cap. That's it isn't it? The holy grail of secrets. Swap out the metal dust cap for a paper cap and life is good. HA!

If I recone a E-110 to a 212X the bass & midrange have different characteristics. VC?

[Don McRitchie]

There aren't really any attributes that are exclusive to MI drivers that I can think of. However, the majority have at least two of the following three attributes:


High power handling
Curvilinear cone geometry
Aluminum dust cap

The first was essential for amplified music and was accomplished by high temperature adhesives, kapton voice coil formers and ruggedized suspensions.

The second is the main reason MI drivers are classified as sound producers and not reproducers. Curvilinear cones were employed in the earliest JBL drivers - pre-dating MI drivers. This was because they allowed greater high frequency extension that mitigated the need for a separate high-frequency driver, or allowed a higher cross-over point for use with a smaller HF driver. The curvilinear cone allows for a degree of mechanical decoupling of the outer circumference of the cone from the inner circumference. This allows the inner portion of the cone to track high frequencies without being constrained by the mass of the overall cone.

The downside of this approach is that the decoupling results in a degree of distortion. This is why the D130 and 130A drivers have a very distinctive sound compared to later LE15A. In MI drivers, this can be accentuated to result in a euphonic sound that was considered desirable in that market. However, they were the antithesis of accurate reproduction.

The aluminum dust cap was a further means of HF extension. However, these drivers have a rather ragged, falling HF response. While this is of limited utility in a full range hi-fi application, is well suited to the narrower bandwidth of such instruments as electric guitar.

As always, nothing is absolute. There are MI drivers that do not use curvilinear cones or aluminum dust caps. However, most are designed to have a specific sonic signature, that while not accurate, was felt to accentuate the character of the instrument being played. This was particularly true of drivers intended for amplified electric guitar.

[Robh3606]

Heres a Tech Sheet from the Library that will help explain the differences on how the speakers are designed for various applications.

Rob:)

http://www.lansingheritage.org/html/jbl/reference/notes/tech1-3a.htm

[tinnitus]

:jawdrop: I now know that I know nothing.

I will now take my book and sit in the back of the class and do my reading assignments. :slink:

I won't even try an enclosure for E-155s. Recone ASAP.

[spkrman57]

No matter how many times I read that tech literature, I still gleam something new everytime I read it.

Ron



Heres a Tech Sheet from the Library that will help explain the differences on how the speakers are designed for various applications.

Rob:)

http://www.lansingheritage.org/html/jbl/reference/notes/tech1-3a.htm

[Tom Brennan]

I read that some of the Altec MI drivers had chamfered gaps so that distortion rose with increased volume thus giving a particular sound.

[scott fitlin]

I read that some of the Altec MI drivers had chamfered gaps so that distortion rose with increased volume thus giving a particular sound.On Todd Whites board they talked about this once, and said it also helped mellow the tone of the midrange.

[Earl K]

- 417 alnico (http://www.hostboard.com/forums/search.php?searchid=95524) ( this is a linked search of his treads at Hostboard for those registered ) is a sometime poster over at Todds' .
- He's explored some of the nuances of the Altec M.I. twelves inchers that came about from the various generations of that specific product .

<. cheers