JBL LSR4300 Series

[deals4you]

Has anyone had any experience with these monitors, i'm athinking of getting some.

[645824]

I have 3 of the JBL LSR 4328 and I'm using them in a center + left + right configuration. I am very happy with the units. But there are a couple of things to recognize:

1. the RMC system looks at numerous frequencies (72?) but only adjusts the filter for one of them. This becomes obvious when running the Control Center software. You will see a notch at only one frequency and the rest of the spectrum is flat.

2. to get the units to communicate with each other, numerous wires are needed:
a. each monitor has a 120VAC power cord
b. each monitor has a signal cable (analog or digital)
c. each monitor is chained together via the ethernet cable
d. the front left monitor has a USB cable (to the computer) if you want to use the Control Center software

3. the air port is on the back. So wall placement is a little tricky. But I haven't observed any problems


I've had my units for several years now. I only have 1 issue with them:

When there is a brownout or the power drops out, the monitors don't kick back in automatically. i.e. I have to unplug, then replug each unit before it will respond again. I asked JBL about this a couple of years ago and they said that it was a feature. I wish this feature could be disabled! I run into this problem sometimes when the large institutional A/C unit kits in and puts a drag on the voltage level. I am indeed running the latest firmware (2.2)


Hope this helps,

Scott

[645824]

One other thing that I've noticed is that I am seeing a discrepancy in the reported firmware version between the Control Center software and the units themselves (via the LED's).

The units themselves say that they have version 2.2 firmware (which I installed) by showing 2 green and 2 yellow LED's during the initialization phase when the monitor powers up.

However, the Control Center software says that each unit has version 2.1 firmware (shown in the popup window for each monitor):

LSR 4328P 2.1

and the Control Center software User's Guide Reference (page 9) says that this is indeed supposed to be the firmware version of the monitor.


Is anyone else seeing this discrepancy?

Thanks,

Scott

[645824]

After I went through the RMC calibration procedure, I used the Radio Shack sound level meter to measure the values at various frequencies at the listening position where I did the RMC calibration

Here are the results:

Hz SPL
-- ----
20 54
22 58
24 62
25 65
26 67
28 69
31 75
35 79
41 81
45 79
47 79
50 78
53 74
57 73
62 80
68 84
76 89
85 92
90 93
95 92
105 91
115 87
126 87


I used a sine wave generator to step through each frequency, and I measured at each frequency using the Radio Shack SPL meter with C weighting. I selected the frequencies based on JBL's RMC graph paper that I downloaded from jblpro's website.

http://www.jblpro.com/catalog/support/getfile.aspx?docid=1011&doctype=3

Note that the absolute SPL level was selected arbitrarily -- I just set it to a mid-range value at the highest frequency knowing that the lower frequencies were going to fall off. On the JBL 4328's, about half of the LEDs were lit up when the sound was playing and my listening position is 17 feet away from the left+center+right speakers. My background noise level during this simple test is 51 dB because of various equipment fans, etc. that are on right now. So the lower frequencies are running into the noise floor in this room.


As you can see, the sound level isn't flat. The attached XY graph shows the data. The horizontal axis is indeed a log axis, but I couldn't figure out how to make Excel make lines closer than 2X together on a log scale (hence axes lines only at 20, 40, 80 Hz).

I am a little disappointed how "unflat" the response is. This probably stems from the RMC only putting a notch in one place in the spectrum (around 50 Hz in my case). From 80-120 Hz it only varies from 87 to 93dB and this seams reasonable for an 8" speaker. Well, that's why they make subwoofers. If JBL did full spectrum RMC leveling then that would be impressive. Perhaps a new firmware will incorporate that...

Note that the JBL response curve is shown in a chart in the spec manual for the 4328 so there is a known fall off starting around 60 Hz on the JBL plot:

http://www.jblpro.com/catalog/support/getfile.aspx?docid=570&doctype=3


The funny thing is that I can't hear anything below around 30 Hz (this was a surprise to me). The meter says that the speakers are putting out sound at these frequencies, the LEDs on the speakers themselves show that sound is coming out, and my 4 year old son says that he can hear it. But at the frequencies below 30 Hz I hear absolutely no output.


Scott

[DAS]

Must remember that room modes also exist in the time domain. None of your measurement techniques will "see" that, but your ears will hear it. On the graph it looks like the RMC is pulling more energy out at 50 Hz than is really needed, but when considered in the time domain it may be necessary. Use your ears to compare and see if it is working for you.

Yes, it would be nice if the RMC could address the other issues in the room, but again we must remember we are to some extent trying to address time domain problems with amplitude correction. This is a loosing battle, and is why this equalization must be done in concert with acoustical treatment.