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Author Topic: JBL datasheets Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 03-19-2014 06:42 AM                     Hi all, Is is just my impression or JBL datasheets have become very inaccurate these days? I find difficult to find the sensitivity of a speaker, which is showing different figures on different datasheets. Even dimensions are wrong, I personally measured a 4722 speaker to find out that the "LF" height shown on the datasheet was actually the height of the whole speaker. Not to mention the overenthusiastic sensitivity management: a single 100dB peak at 1000Hz and the whole speaker is then rated "100dB 1W/1m"! Am I the only one noticing it?  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 03-20-2014 03:41 AM                     I have not their datasheets to be a problem. The one I just downloaded looks right...it shows the height of the LF cabinet as well as the overall height. The sensitivity, JBL does play games since they don't use the 1W/1m anymore...they tend to reference 2.83V...which works for 8-watt systems only. Since the 4722LF section is a 4-Ohm cabinet, one has to lower the sensitivity rating by 3dB. However, 101dB 1-watt/1-meter is consistent with a dual 15" cabinet of this design. I don't know where you got the 1KHz 100dB specification, I haven't seen it. However, since that is above the crossover point, one would have to take the HF sensitivity which is going to be considerably higher than 101dB. Unfortunately, they do not list the sensitivity of the HF section by itself. Incidentally, I've found that the 4722 to be one of the best bang-for-the-buck speakers currently in production. It sounds very good (a key feature), its price is very reasonable, it tunes up well with almost no EQ needed in most rooms (with normal RT60 qualities). Though the passive crossover is nothing to write home about (it is also very cheap), actually matches the two sections well enough that one need not apply excessive EQ. The neodymium HF driver makes the HF section nice and light...which helps on installation.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 03-20-2014 04:30 AM                     JBL 8320 as an example: the free field sensitivity is mostly below 90dB but JBL claims the speaker has an overall figure of 91dB because it touches 91dB at 7/800Hz. JBL 4645C, 97dB on spreadsheet, but without EQ. 4677: datasheet gives an overall height of 126.5cm, and the LF height of 128.9cm (didn't say the 4677 are bad, just the measures are wrong, and its figure of sensitivity is ok)  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 03-20-2014 06:06 AM                     I think you are really barking up the wrong tree here. The measurement methods are standard and consistent with others. Again, the thing to watch is that they use 2.83V rather than 1-watt. Most sensitivity ratings are band limited. With subwoofers, it is often not in the area of interest either. As for without EQ...well yes...EQ takes away from power handling of any speaker. Again, I think there is nothing inconsistent with what JBL is specifying than others. One can compare apples to apples. If anything, JBL provides MORE information on the 4645C than typical subwoofer specs. Be upset with them if you want, I think you are wrong on this one.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 03-20-2014 05:06 PM                     I see your point but I won't be happy with JBL just because they provide a little more info than the others - but still not enough/not accurate enough. And the 4722 height is wrong!  |  IP: Logged

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