Actual differance between 2220 and 2235 baskets

[Flodstroem]

Hi !

This is a question that Mr Widget can best answer I think, but others are welcomed.

In many of the former threads there have been discussed dimensions of baskets, cones, what re cone kit is going to work in what speaker etc...
In many of these threads it says that the 2220/130 is completely different from other speakers like the 136, 2205, k130, 2235 etc...

What is the actual mechanical difference between the two
bass driver baskets 2220 and 2235 (measured in mm). I know the topplate for the 2220H is 9 mm thick/deep, but what is the measured dimension of the
topplate for the 2235 ? Between the two loudspeaker models, Is there a mechanical differance in the frames too (hights) ?

It would be interesting to get to know how many speakers and what models you (Mr Widget) might have on your mechanical dimension list ?

Best Regards
Flodstroem

[Mr. Widget]

I have not been keeping a list. I know that many of the specs have been posted on various threads, but it may take a few searches to find the relevant data. Just looking at the woofers the 2220H looks like a 2235H, 2231H, 2225H, and 2205H. There are no 2235A or 2225As, but the 2220A looks like the 2231A and 2205A.

If you place them next to each other you notice the 2220 is overall taller than the others of their respective series A or H. This is due to the larger motor structure (top plate and magnet). JBL has produced several baskets for their 15s over the years generally the only change is location of the input connectors, but I have noticed some of the older baskets were of slightly different diameters... I haven't kept track of that either. Bo and Giskard are much better at lists, I think it is a left brain right brain kind of thing. If you need specifics you will have to do some searching or perhaps someone will come to the rescue.

Widget

[Flodstroem]

OK. Mr Widget.

Thank you for answering.
I will keep on searching for the data, if nobody else at the Forum are sitting on it (eg. Bo and Mr Giskard).

Best Regards
Flodstroem

[subwoof]

The 2220 series has a *deeper* gap than the 2231 / 2205, et all.. It's magnet is an orphan in the JBL line.

Since it used the same frame as the 2231 putting anything other than a 2220 kit into it will result in non-symetrical operation at larger excursions. And unfortunately shimming the magnet / frame junction won't work because that moves the offset in the *wrong* direction and milling down the frame 1/2 of the difference will weaken the frame to the point of instability.

We tried, man we tried....picked up 40 baskets one time from an auditorium and created more aluminum shavings than we care to admit...

This is also noticed when using the K145 / 2215 / LE15 magnets - those have REALLY deep gaps.

Somewhere giskard published a table but searching for it would require some time as there is currently NO library for this on heritage..



sub

[Flodstroem]

Subwoof, thank you for replying.

I got the point. (Sorry your 40 baskets milling projekt did´n work)
What I have found out is that the topplate differance between the 2220 and the others (2205, 2225, 2231 etc etc) seems to be 9 mm to 7,1 mm. This will be a total difference of 1,9 mm. The offset error will then be half of that, eg 0,95 mm. Is this right ?

If it teoretically was possible to adjust this offset to be zero, what performance could we then expect to have for this 2220/2235 clone ? A real 2235 ? (guess they have both 1,2T magnet flux)

But this is a rather hypotetical issue, or ?

Best Regards (cheers Subwoof)
Flodstroem

[4313B]

The 1.35 T*m assembly (E140 for example) uses the 7/8" thick magnet and the 0.280" top plate.

The 1.20 T*m assembly (2235H for example) uses the 3/4" thick magnet and the 0.280" top plate.

The 1.15 T*m assembly (2220H for example) uses the 3/4" thick magnet and the 0.350" top plate.

The 0.95 T*m assembly (2215H for example) uses the 7/8" thick magnet and the 0.600" top plate.

[subwoof]

If you managed to correct the offset it would have a slightly higher efficiency ( more coil is in the gap at any given time ).

The Xmax would also change

And the Fs might be higher since it usually rises with a stronger magnet ( the coil will "see" more magnetism ) and the freq response does too.

Hmmmmm

sub

[Flodstroem]

Thank you Giskard and Subwoof for your data feedback.

Now I realize what the real differances are between the two main-models.
Interesting Subwoof, what an opportunity, if there was any possibllities to machining down an 2220A/H frame to the right dimension.

Best Regards
Flodstroem

[Eaulive]

The 1.35 T*m assembly (E140 for example) uses the 7/8" thick magnet and the 0.280" top plate.

The 1.20 T*m assembly (2235H for example) uses the 3/4" thick magnet and the 0.280" top plate.

The 1.15 T*m assembly (2220H for example) uses the 3/4" thick magnet and the 0.350" top plate.

The 0.95 T*m assembly (2215H for example) uses the 7/8" thick magnet and the 0.600" top plate.

Ahhhhhhhhhhhh!

I was looking for this kind of data since a long time.
Where did you get it? Is there any publication by JBL about the other drivers?

[4313B]

Ahhhhhhhhhhhh!

I was looking for this kind of data since a long time.
Where did you get it? Is there any publication by JBL about the other drivers?

Not that anyone is aware of.

[nders]

The 2220 series has a *deeper* gap than the 2231 / 2205, et all.. It's magnet is an orphan in the JBL line.

Since it used the same frame as the 2231 putting anything other than a 2220 kit into it will result in non-symetrical operation at larger excursions. And unfortunately shimming the magnet / frame junction won't work because that moves the offset in the *wrong* direction and milling down the frame 1/2 of the difference will weaken the frame to the point of instability.

We tried, man we tried....picked up 40 baskets one time from an auditorium and created more aluminum shavings than we care to admit...

This is also noticed when using the K145 / 2215 / LE15 magnets - those have REALLY deep gaps.

Somewhere giskard published a table but searching for it would require some time as there is currently NO library for this on heritage..



sub

Is it enough to get coil to sit deeper?? Aftermarket kits where cone coil and spider are sold separate could be an alternative to get the coil deeper in the gap? easier than to mill down the basket..

/Anders

[1audiohack]

I believe that would work. It would at least get the coil to top plate symmetry right.

Welcome to Lansing Heritage. What are you working on?

Barry.