Ok. We're pretty much familiar with the nomenclature JBL uses to identify impedance of it's various drivers, 'G' equals 4 ohms, 'H' equals 8 oms, 'J' equals 16 ohms. Once upon a time they used 'A', 'B', etc.
- Did they ever use the letter 'I' for anything, since it's between 'H' and 'J'?
- Have any 'K' (32 ohm) ohm products ever been produced?
- Why the switch from 'A', 'B', to 'H', 'J'?
Regards,
Charley
A type speakers had alnico magnets, the H types are ferrite. Not so sure about the others.
The ferrite and alnico *musical instrument* speakers used either no suffix or added the -16 ( example ) after the model number.
The 32 ohm cones ( C suffix ) were last used on the alnico pro line. They were popular replacements for theater organ installs ( IE: 2205C and 2220C ) because of the taps found on tube amplifier output transformers.
And the consumer...well they had their own planet....
sub
On the side of my JBL units It says ...130B- 32 ohms ....., these are very early JBL woofers.
Nomenclature implies a standardized identification system in place for referencing design, part, or options changes on model or part numbers. I have tried to make sense of such on JBL products, and have concluded that there is little or no such standardization as such at JBL.
Take ring radiators, for example. The 075,076,077, 2402,2403,2404, and 2405 are all basically the same motor assembly, yet the various incarnations of the same models have been marked 8 or 16 ohms, yet all use the same diaphragm. On parts lists/exploded diagrams/schematic data sheets for certain JBL speaker systems, some of the 2404H drivers are noted as 8 ohms while others are noted as 16ohms. There are actually two diaphragms that fit these drivers, but both use the same voice coil. One is a part# D8R075, the other a D16R2405. The only difference is a slight difference in frequency response (and supposedly durability) between the two, due to minor mechanical differences that are unclear.
Many diaphragms and drivers have a "-1" suffix on their model or part number. Often, this indicates the use of ferrofluid in the voice coil gap for higher power handling (heat transfer). However, the "-1" in the 2404-1 driver doesn't appear to have ferrofluid at all.
Same goes for "HPL" For my own 2035HPL woofers, someone told me it meant aquaplas coating was used. Someone else told me it meant that a rubber ring was installed around the magnet -which mine do not have. On any of the 6 of them. Someone else told me the aquaplas-treated woofers had a "-1" suffix tacked onto the 2035HPL model number.
However, my 2447H drivers DO have rubber rings around the magnets -and no "PL" suffix. 2450SL drivers use diaphragms dusted with Aquaplas. Go figure.
Bottom line, as I see it: if JBL uses a standard nomenclature, it is NOT indicative of the same thing in every case -if in any case at all. In MY experience, at least...
Given the size of a Company like JBL, the length of time in business, the age of some of their products, and all the variations produced for one reason or another, it is not surprising that this happens from time to time. But acknowledging this doesn't help... and trying to match up, repair, or retrofit a system with available parts can sometimes becoma a frustrating experience with less than anticipated results.
I wish there were or at least a reference to what the variants are in each model or part number. It seems that even JBL Pro Service is unsure at times: I have asked different Techs at JBL Service the same question on the same part or Model number and received different answers or even an "I don't know for sure".
If any of the old JBL'ers could shed some light on this for you, hopefully they will read this thread and respond for you.
Originally Posted by Charley Rummel
I once read in an old JBL document that the letter choices signified two things.
First, The letter "H", being the 8th letter of the alphabet= 8 ohm nominal impedance. The letter "I" is too easily mis-read as a "1", so it was skipped, And the next easily distinguishable letter "J" used for the next higher nominal impedance normally used= 16ohms. "G", the next letter down=4ohms, the next lower nominal impedance normally used.
Secondly, the letter suffix came about concurrently with the discontinuation of AlNiCo magnet structures, and (I think) the G/H/J letter suffix also indicated that the driver used a ferrite (ceramic) magnet. I may be wrong on this second note, as I am relying on memory.
If I am wrong on this second point, I'm sure the JBL gurus here will correct me.No flames guys! But I do know the 8th letter thing is accurate.
2404H-1 uses the thicker 2402/075 diaphragm. More rugged for SR use, and safely crosses lower. Less UHF response as a concomitant consequence.
Interestingly, tech sheets say replace with 2405 diaphragm, making them into stock 2404H. Go figure....
The "PL" designation means private label where the H means 8 ohm. Jbl removed the magnet tire on some models that were used in the SR and concert series boxes to save all of 50 cents and used a label that had no red color....
JBL sold raw frame woofers to other speaker companies with this label. One example is the community quad 15 sub that had 2226HPL's with an extended pole piece with a second spider. Strange looking and it was prone to ripping...
I order the 2217H 14" cones from parts since they are not available from the regular component line. And they are "PL" also. Ditto for the 2435H's that are sold on ebay all the time.
The "-1" designation meant an improved diaphram but not the ferrofluid. There are no components ( that are sold seperately ) that uses it, only some components that are incorporated into assembled systems.
remember the phrase:
"above all else confusion reigns"
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In this vein, anybody know what a D130 BP is?
The only "P" usage I have seen is the "high power" version of stock components that were made for outside vendors ( dukane, sunn, heath, rca, etc ) and were the compression drivers ( IE: 375HP or 275HP ) that had phenolic diaphrams.
I seem to remember an old JBL book that a dealer I worked for had that said the paper cones were also available in a "beefed up" version on special order.
I wish I got more of that old lit when the place closed but I did manage a number of binders with spec sheets.
On another vein. I owned a pair of 130-4C speakers that had a thick, heavy paper-mache' dustcap and it appeared to be original.....
There must of been multiple variants of the 130 since it was the original ( and only ) frame for years.
But of course since JBL never wrote it down. who knows....
sub
Last I heard, "PL" is "Protector less", lots of finished products come like that; At least We know that it does not have the rubber protector around the magnet, that is, until JBL throws us another curve.
The lack of standards in nomenclature has been with JBL since the beginning, and was also present in Jim Lansing's earlier products. His original large format compression driver was called the 284, presumably because the inner voice coil diameter was 2.84". Later drivers in the series were called 285, 287 and 288, though they used the same size voice coil. What happened to the number 286? Nobody knows.
The JBL drivers of the late 1940s and early 1950s were given what now seem to be nonsensical serial numbers. These were actually code for lot numbers and possibly production dates, now indecipherable.
The designation "E" was used in the early 1950s to denote an electrodynamic, or field coil driver. The company built a few D-130-E and 130A-E drivers at the beginning of the Korean war, when they feared they might lose their supply of Alnico magnets.
It's reassuring to see that JBL has been consistently inconsistent from the beginning.
Widget
Actually, they've recently expanded to using 'F', to designate 2 ohm drivers. As an example, we recently pulled a 252F from a powered cabinet... 2 ohm diff-drive-neo-motor driver.
Regards,
Gordon.
Can anyone illuminate on the distinction between the G, H, and J designations? Some claim to know these relate to "impedence" - true???
bo
"Indeed, not!!"
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