Has anyone else tried blocking up the ports on JBL Control Ones?
I just bought some to try as they are pretty cheap and very well received in reviews. First listen they seemed to do what some pro JBLs do which is pretend to go really low by having a hump in the upper bass region. Blocking the ports has reduced the hump and therefore the overall low end, however they seem to be smoother lower down, which I like.
Has anyone else tried this on these or any other speakers?
Blocking the vent on a ported speaker will alter the system "Q" of the speaker. The "Q" factor determines several things about a speaker's performance. The first is efficiency, if you've susseeded in totally blocking the vent, the system sensitivity will be reduced by 3dB. Also, if you have effectively blocked the port so no air escapes, a difficult task after the speaker is built, you have turned the enclosure into a sealed, accoustic suspension type. This will raise the cutoff frequency of the driver/enclosure system, usually by at least an octave. I will also establish the typical sealed enclosure roll off of -12dB/octave rather than the steeper -24dB/octave of a ported system. So the driver will not play as low or as loud though the lowest bass octaves as with a properly designed vented enclosure but it will roll out more gradually due to the sealed enclosure's infinite baffle construction. Stuffing the port cannot, however, remove any humps in the frequency response which the designers might have built into the system and which occur above system resonance.
If there are any air leaks around your port, the system still operates as a vented enclosure although with some modifications that result in what would be most similar to an aperiodic enclosure. Without proper tuning this creates a spike in both the frequency response and in the mechanical impedance of the system. Since it is dificult to totally seal the port on an already built speaker, this is more than likely the situation you have created.
Either way, you have altered the "Q" of the system and not all drivers will appreciate going from a ported enclosure to a (semi)sealed box. Some will but most won't, it depends on the "Qts" of the driver which, I assume, you don't know. The speaker will still respond to a music signal but its frequency response and impedance will change in unpredictable ways.
While I understand the system might sound better to you with the ports blocked, this is not really a good way to go about achieving respectable frequency response. Even on budget speakers a fair amount of effort has taken place to achieve the proper system resonance of the JBL speaker. If you are having problems with boom and one note bass, the first solution would be to change the placement of the speakers within the room. It's quite possible the speakers you now own cannot produce smooth bass response but it's also possible you have a room with multiple, high "Q" modes that are being excited by the speakers in their present position. I would suggest you unplug the ports to restore the speakers to their original specs and then put "loudspeaker placement" in a search engine. Try the "WASP" placement techniques before you decide whether your speakers can sound good without stuffing a sock in their ports.
Some speakers are designed to acommodate sealed and ported. In such designs, neither is ideal, IMO. JBL is probably the least likely example to achieve this goal, followed closely by Cerwin Vega. Simply a tool to add to a less than stellar toolkit. While some Totem products do add a port plug to the package, I still believe that the original design of the engineer does not include the pssibility of ported/sealed options. I believe Stryvn has tried his Paradigm Studio 60's both ways...anybody else?
ps, I plugged the ports of my Psb's with hockey socks, and that just didn't work at all. But in my present placement, it really doesn't mtter.
Yes, clearly I've changed the Q of the port system but the resonant frequency with open ports is too high and plugging the ports has reduced this resonance. I'm really not worried about the sensitivity at the low end, it was too much before - which was why I started doing this. But the low end extension caused by the gentler roll-off is definitely better.
As far as placement goes, I'm rather hampered by two things. Firstly, they are around the TV with the centre speaker as close to the TV as possible and the tweeters at pretty much the height of the centre of the screen. Secondly, I am happily married and intend to stay that way!!
Generally, I think of ported designs as a way of getting more bass out of a speaker at the expense of the low-end extension. Good designs on big speakers are fine but on these little JBLs where the port is very close to the driver, it sounds more like a marketing design from the "more-bass-is-better" marketing philosophy.
In theory I have completely screwed up the design, however, my ears tell me otherwise. I think I need to get some proper tests done on these speakers - with and without the corks. But I would still like to know if anyone else has any successful experiences plugging ports.
In my limited experience, I have always thought port plugs were to be used solely in a 5.1 system where a subwoofer is employed.
Also I have heard them suggested for a rear ported speaker when it is placed very close to a wall.
But my thought is that, if the speaker was developed and designed with the port, and possibly tuned with the port, why plug it up?
Both my HT fronts and surrounds (Energy C-100, C-50) came with foam plugs. The dealer said I should use them since I was wall mounting the speakers and the lack of air space for the rear ports would muddy the bass.
I have not tried them without the plugs, nor would I expect much difference. I dont listen to my 5.1 setup in that fashion.
(Although I did hear an impressive battle scene in some silly scifi network movie when I was flipping channels last night.)
On another note... regarding ports and plugs.... My Naim Ariva speaker is a sealed design... not ported. I have never heard this before in person, and I must say i REALLY like it. The bass is so taut and quick. Amazing.
I'm really interested in the fact that the Energy system seems to be designed to work both ways - ported or infinite baffle. The manual doesn't discuss it but it does show pictures with and without the foam plugs.
I'd be interested to know where the salesman got this idea about using them plugged with a sub or up against the wall. But I'm glad it isn't just me that sees ports as an optional extra.
I run the JBL control exclusively for the surrounds while JBL control 5 takes control over LCR. The Control 1 add nice insane warp around so easy to install and I've forgotten which film adds the highest level in the lower end. They can't reach down to far at high SPL db but with a little sub bass extension its seamless.
Around 80Hz upwards there good I'd hath to run further tests while LCR LFE.1 is muted.
Surrounds are wired in series and I've had no issues with there operating performance in the past 18 or is it 20 months now, hmmm, I forgot which year I bright them, think it was 2006?
In all there are x10 JBL control 1 x8 are fitted up at present and I still need to get at least another 10 or 12.
HSU supplies a port plug for 1 of 2 ports of there subs. You also flip a switch which does??? One way is 'maximum output' the other way is 'maximum extension'
