116H and 116A differences

[tweeter]

Hi,
what are the differences between these woofers?
Are they electromechanical and cosmetics?
Could be possible to replace one of them by another for a 4301B?

Thanks.

[Fangio]

116A = alnico magnet
116H = ferrite magnet

you can learn a bit about the background here: The Great Alnico / Ferrite debate (http://www.audioheritage.org/vbulletin/showthread.php?t=4031)

[doyall]

Also check out the L19 and L19A Technical Manuals. L19 uses the 116A, L19A uses the 116H. Slightly different DCR specs. Cone kit for each is the same. LF network is the same. I would bet any acoustic/sonic differences would be difficult to discern, although other posters have noted distinctions between alnico/ferrite versions of a different model transducer. Maybe someone with more technical knowledge could advise whether any electromagnetical problems could occur by a less than a pair substitution.

[tweeter]

Any cosmetic differences?
How I can distinguish both models with a look?

B.R.

[Zilch]

116A alnico magnet is a simple dome on the rear.

116H ferrite looks more like a wheel.

I do find measurable differences between them, but would have to do that with multiple units to confirm statistically before concluding anything.

"H" obviates any potential demag problem, so I prefer using that version for closed-box Minis.

[edgewound]

"H" obviates any potential demag problem, so I prefer using that version for closed-box Minis.

I think you meant "A" obviates the potential demag prob....no?

"H" is the ferrite version. Probably just a typo.

[johnaec]

ob·vi·ate(bv-t)
tr.v. ob·vi·at·ed, ob·vi·at·ing, ob·vi·ates
To anticipate and dispose of effectively; render unnecessary.

'Sounds like Zilch is correct to me...

John

[edgewound]

ob·vi·ate(bv-t)
tr.v. ob·vi·at·ed, ob·vi·at·ing, ob·vi·ates
To anticipate and dispose of effectively; render unnecessary.

'Sounds like Zilch is correct to me...

John

Ok...then why would one choose the higher motor strength for a closed box design? A diminished magnet 116A would be a more likely candidate for a closed boxed.

Whatever.

[Zilch]

The best information I have is the T/S parameters for the two driver variants are the same, so the fundamental performance in any alignment would be as well, as I understand it. The "A" and "H" versions are equally wimpy, and thus well-suited to closed boxes.

I choose the "H" ferrite version because GT suggests the Decade "As" are among the group of drivers most sensitive to potential demag with drive, and because the small closed-box alignments are inherently inefficient and require more drive to achieve SPLs comparable to the vented alignments in which they are more conventionally employed.

My major problem is that I cannot get contemporary factory kits to fit the vintage motors, and I've never seen any refoamed ones of either type approach the originally spec'd 28 Hz Fs. It may well be I'm using too-heavy aftermarket foams here, and I want to check that out in comparison to factory kit recones....

[johnaec]

Whatever.I was only referring to Zilch's use of "obviates" when referring to retaining magnet strength...

John

[edgewound]

. The "A" and "H" versions are equally wimpy, and thus well-suited to closed boxes.

I choose the "H" ferrite version because GT suggests the Decade "As" are among the group of drivers most sensitive to potential demag with drive...


Zilch, John,

I understand your thinking now.;)

[edgewound]

My major problem is that I cannot get contemporary factory kits to fit the vintage motors, and I've never seen any refoamed ones of either type approach the originally spec'd 28 Hz Fs. It may well be I'm using too-heavy aftermarket foams here, and I want to check that out in comparison to factory kit recones....


Does that mean you can't get factory kits, C8R116A? Or...you can't get them to work right? The shim stock you use can be the key to making it work...unless of course the kits are defective:p which can be a problem.

C8R116A is available, though.

[Zilch]

Does that mean you can't get factory kits, C8R116A? Or...you can't get them to work right?My reconer has the kits, but the voice coils do not fit in the gap without rubbing. We have cleaned, polished, and honed, all to no avail.

I have advised him to send the cores and the kits to JBL Service and let them deal with it. Those kits are NOT cheap, as you know.... :banghead:

[edgewound]

. We have cleaned, polished, and honed, all to no avail.

I have advised him to send the cores and the kits to JBL Service and let them deal with it. Those kits are NOT cheap, as you know.... :banghead:

Sounds like a high VC wire or maybe an out-of-round coil.

It's been my experience lately that the vintage coils sometimes need to be trued up with a coil form die.

[mech986]

Hi Zilch,

Regarding the 116H recone kits, did you ever get this voice coil rubbing issue sorted out?

I am assuming that the 116 frames' gaps were nice and round and correct, honed (as you mentioned). What did you eventually do?

Regards,

Bart

[Zilch]

We eventually got one to work, but damaged the surround in the process, so it now has a new surround, and my intention to discover if factory recone kits actually yield Fs to spec is moot.

The second one will be going back to the factory with the H-1 frame so that they can deal with it.... :banghead:

[mech986]

Thanks for the update Zilch. Seems to me most shops would be able to at least measure the thickness and maybe the density or compliance of the factory surrounds and compare them with the various aftermarket surrounds available.

I've seen quite a few for this driver and other JBL's and many of them seem to be very thick and less compliant (stiffer and more springy) than it would need to be to get a low Fs. This seems especially true with the 2235 series where most of the aftermarket surrounds are too thick, too wide (wide roll vs narrow roll) and too springy, even after breakin.

I was under the impression that there were many variations on the thickness and one has to find the right supplier (who has to have consistent supply to them, I suppose). Thicker probably is longer lived and more reliable (a concern) but may not allow the bass-mid driver to hit its specifications, sort of obviating the whole process of refoaming?

Regards,

Bart