Hi all,
A spirited discussion is on about the 4343B of an AK member, and the question of power handling came up. Here's a link, and I'll pull out a couple of posts. Help me out as to what is the correct interpretation of the specs and maybe what your real world experience is with the 4343B in particular, and the ability / capabilities of the 4 way Studio Monitors in general. The question about power compression is also an interesting one.
http://www.audiokarma.org/forums/sho...78#post8776578
Originally Posted by twiiii
A very nice system indeed. Maybe not as efficient as the bigger brothers or having the advanced woofer with lower distortion, but still a great performer. Connect the speaker to a MC 752, 754, Mc7100 with Power Guard to protect your valuable drivers and you would have winning performers. Maybe a little bright for me, but that's what tone controls are for. 114 db maximum output is all you need to recreate live unamplified concert levels will great precision. Now if you are a devote' of live rock concert levels you will have to climb a little further up the JBL ladder. You are going to need another 10 db in out put capability.
Those should be around 94dB at 1-watt. I have no idea what you're talking about—they should rock with the best. The only step up would be the 4345 with the 18-inch woofer (mine) or the 4355 with two fifteens.
There are a lot of JBL's that are stronger than 4343, either by efficiency or other models that can handle almost a magnitude more power. Some don't quite reach as low to gain more efficiency or to handle more power. Other reach even further down or give up some highs, like the two way systems. Then there are others from the DD series or the K2 series that out perform the speaker, 4343, due to modern updated materials and driver design, the DD series, or the smaller members of that related family. When a speaker system is only rated at 75 watts and 102 db at 10 ft you know it is either a compromised design or from a time in the past.
Sure, but you're relying on the JBL brochure. I can't imagine the 4343 isn't capable of room-filling sound for the average owner in a residential setting. I know what my old 4345 is capable of. I just thought your comments were less than encouraging to a new owner. :thmbsp:
Have you actually listened to a pair of 4343s? 4333s? 4345s?
Or a sign of a very conservative rating based on a commercial application....probably continuous use at full rated power....not "peak" power ratings as commonly found today.
Yeah, they did rate them differently in the past for the pro market.
http://www.jblpro.com/pub/obsolete/4343b.pdf
Sensitivity of 94db/1w/1meter
Acoustic power output: 102db at 10 ft (about 3 meters) at 1/2 rated power, (about 37W) in a room volume of 57 m3 (2000ft3) (say a room 9' x 12' x 18' which is decently sized)
Conservative power rating: 75W continuous sine wave, 1975 era. (most of us today would be quite comfortable with running 200-250W/channel easily, given the power ratings of the 2235H woofer, 2122 midrange, and 2420/horn, 2405 tweeter with proper attenuation and crossover power management.
Note the caveat in the brochure:
Caution: Sound pressure levels produced by the 43438 may cause
permanent hearing loss. The suggested maxlmum exposure is 115dBA for no more than 15 minutes (Department of Labor Bulletin #334).
Loud and powerful enough for you? The 4343B is essentially a JBL L300/4333B monitor with an additional 10 inch high powered midbass/midrange cone driver which would allow the compression driver upper mid and UHF slot tweeter to run even hotter.
Here's the revised L300 tech sheet from JBL circa 1992. Max recommended power is 300-400W non-biamped, using essentially the same drivers sans the cone midrange. Anyone who has listened to an L300 at 100W will tell you that's insanely loud, and given 6db headroom with 300W-400W of power, well, the permanent hearing loss, and window/wall damage could be considerable.
http://manuals.harman.com/JBL/HOM/Te...ummit%20ts.pdf
Here again we go back to how JBL measures its speakers. Normally a speaker rated at rms value can handle peaks of 6 db. So that would mean 300 watt peaks for the 4343. The question then becomes do I use a 300 watt amp and hope the rms value of the signal never exceeds 75 watts over the given bandwidth specified by JBL. Note I did not say the full frequency spectrum. That's why dealers who sold Altec and EV got so frustrated with JBL. Because EV and Altec rated there speakers over the full spectrum in the 60, 70's and early 80's when JBL was playing games with numbers. By limiting the bandwidth the efficiency numbers go up and depending on the function of the driver the more power can be handled. Where if you test the speaker over the full published response of the speaker you will get a different result. Now I realize music is not linear in response or concentration of energy and JBL's methods of yore approximated the capabilities of their systems when driven by most musical sources. But as listeners tastes changed and recording systems and techniques changed power handling of speakers had to improve. So today Professional manufacturers are pretty much playing by the same rules. Where with consumer speakers its anyones guess.
So yes for 40 millisec peaks your speakers will possibly put out 120 db, with a rms value of 114 db. But at what point do your drivers become non linear, where added power just adds heating to the voice coils and increases distortions. JBL current speakers collapse any where form 3.2 to 4 db at maximum peak power. And they take the distortion measurements at -10 db. So if you apply those standards to your speakers and from reading the distortion specs if you want to remain below 2% distortion. A 100 watt amps is all you can really use. Other wise you are just increasing the distortion you are listening to!
Now remember most listeners listen at levels of around 85 db with 6 to 10 db peaks and professional producers and engineers listen at around 90 db with 10 db peaks. So the 4343 is capable of fulfilling those criteria at a 10 ft listening distance. Just don't try to push the envelope.
, JBL Fan mech986 says 
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