Port Plugs

[jsrtheta]

I recently decided to insert the port plugs on my Monitor Audio Bronze BR2 stand-mounted speakers to decide if they sounded better that way than they do with the ports left open. (In the past, I did the same with an old pair of Krell K.5s I have lying around.)

My subjective (so, take it in that spirit) impression has been that they sound significantly better. I had to reset my subwoofer to pick up the increased bass slack, and, no, I have no DBTs to share. Still, I prefer the sound so far.

Anyone doing the same out there?

 

[tmtomh]

Generally speaking, ports - particularly on stand-mount speakers - make a speaker more efficient and enable the speaker to reproduce deeper bass than it otherwise could.

But porting is a compromise - it doesn't generally improve the accuracy and tightness of the speaker's sonic reproduction. So if you have sufficient power to drive the speakers with the port plugs in, and you have a subwoofer that eliminates the need for the standmount speakers to be able to reproduce the bottom couple of octaves, then I would imagine that plugging the ports would indeed improve reproduction - it would just reduce the frequency range that the speakers can reproduce (and would require your amp to perhaps deliver a bit more power to achieve the same volume level).

 

[jsrtheta]

Thanks for the response!

My impressions are, as I said, subjective, but I do hear much better articulation with them ported. Unported, they are supposed to go down to, I think, 42 Hz (not that I have measured, and if they do, they roll off much earlier), so yeah, it reduces the FR of the speakers. But the sub handles that issue.

 

[carlosmante]

Thanks for the response!

My impressions are, as I said, subjective, but I do hear much better articulation with them ported. Unported, they are supposed to go down to, I think, 42 Hz (not that I have measured, and if they do, they roll off much earlier), so yeah, it reduces the FR of the speakers. But the sub handles that issue.

Ported they go down to 42. Plugging the ports they won't go down to 42, maybe they will go up to a higher frequency.

 

[Julf]

Ported they go down to 42. Plugging the ports they won't go down to 42, maybe they will go up to a higher frequency.

"Going down to X" is kind of pointless without defining what it means. -6 dB? -20 dB? Plugging ports leads to a higher "cut-off" point, but also a less steep drop below that point.

 

[Krunok]

Ported they go down to 42.

That is impossible to know without measurement. In-room response varies rgeatly depending on the position..

Plugging the ports they won't go down to 42, maybe they will go up to a higher frequency.

They will certainly start to roll-off at a higher frequency, but again impossible to tell at which exactly without measurement.

 

[carlosmante]

"Going down to X" is kind of pointless without defining what it means. -6 dB? -20 dB? Plugging ports leads to a higher "cut-off" point, but also a less steep drop below that point.

Pointless because if you don't know the basics of internet search there is not point trying to help you. ha ha ha.
https://www.monitoraudio.com/en/support/past-products/bronze-br/br2/

 

[Krunok]

Pointless because if you don't know the basics of internet search there is not point trying to help you. ha ha ha.
https://www.monitoraudio.com/en/support/past-products/bronze-br/br2/

What is your point exactly? They didn't specify anything usefull with that "42Hz - 30kHz" - it doesnt' say anything meaningfull.

 

[Julf]

Pointless because if you don't know the basics of internet search there is not point trying to help you. ha ha ha.
https://www.monitoraudio.com/en/support/past-products/bronze-br/br2/

Wow. I am sorry you are having a bad day.

 

[Soniclife]

Are you high passing the mains or just adding some subwoofer below them?

 

[jsrtheta]

Are you high passing the mains or just adding some subwoofer below them?

Just tweaking the subwoofer settings.

 

[Soniclife]

Just tweaking the subwoofer settings.

So no high pass? It's not clear to me what you mean.

 

[Krunok]

So no high pass? It's not clear to me what you mean.

He probably raised XO point on the sub to match with new mains LF response with plugs inserted. That is pretty much the only thing he can do without DSP. Although even that action would better be done based on measurements.

 

[pozz]

Pointless because if you don't know the basics of internet search there is not point trying to help you. ha ha ha.
https://www.monitoraudio.com/en/support/past-products/bronze-br/br2/

@Julf was referring to the boundary conditions which determine what 42Hz means. See Rane Note 145

Bandwidth or Frequency Response
What is tested? The unit's bandwidth or the range of frequencies it passes. All frequencies above and below a unit's Frequency Response are attenuated—sometimes severely.

How is it measured? A 1 kHz tone of high purity and precise amplitude is applied to the unit and the output measured using a dB-calibrated rms voltmeter. This value is set as the 0 dB reference point. Next, the generator is swept upward in frequency (from the 1 kHz reference point) keeping the source amplitude precisely constant, until it is reduced in level by the amount specified. This point becomes the upper frequency limit. The test generator is then swept down in frequency from 1 kHz until the lower frequency limit is found by the same means.

Required Conditions: The reduction in output level is relative to 1 kHz; therefore, the 1 kHz level establishes the 0 dB point. What you need to know is how far down is the response where the manufacturer measured it. Is it 0.5 dB, 3 dB, or (among loudspeaker manufacturers) 10 dB?

Note that there is no discussion of an increase, that is, no mention of the amplitude rising. If a unit's frequency response rises at any point, especially the endpoints, it indicates a fundamental instability problem and you should run from the store. Properly designed solid-state audio equipment does not ever gain in amplitude when set for flat response (tubes or valve designs using output transformers are a different story and are not dealt with here). If you have ever wondered why manufacturers state a limit of "+0 dB", that is why. The preferred condition here is at least 20 Hz to 20 kHz measured +0/-0.5 dB.

Correct: Frequency Response = 20-20 kHz, +0/-0.5 dB
Wrong: Frequency Response = 20-20 kHz

 

[Soniclife]

He probably raised XO point on the sub to match with te new mains LF response with plugs inserted. That is pretty much th eonly thing he can do without DSP. Although even that action would better be done based on measurements.

Without a crossover I see sub setup as more a case of which bit do you want to get right, and which wrong, even with measurements.

Without a crossover I think IB makes more sense than ported, the bass driver behaves consistently all the way down, and it's excursion is limited, so distortion should be lower. In room reality may produce different results though.

 

[Krunok]

Without a crossover I see sub setup as more a case of which bit do you want to get right, and which wrong, even with measurements.

Without a crossover I think IB makes more sense than ported, the bass driver behaves consistently all the way down, and it's excursion is limited, so distortion should be lower. In room reality may produce different results though.

When you say crossover I'm guessing you are referring to XO that would do high-pass for the mains and not the sub built-in XO that does low-pass for the sub?

 

[Soniclife]

When you say crossover I'm guessing you are referring to XO that would do high-pass for the mains and not the sub built-in XO that does low-pass for the sub?

I am. Without a crossover you have 2 different slopes, so you cannot get correct summed output from the system, in most cases.

Global DSP can fix it, and some subs may be able to setup to fit their output to the mains, but if you have this level of control it's best to take the strain of the mains as well.

 

[Ron Texas]

He probably raised XO point on the sub to match with new mains LF response with plugs inserted. That is pretty much the only thing he can do without DSP. Although even that action would better be done based on measurements.

There is another way. Get an inline passive filter: https://www.parts-express.com/harrison-labs-fmod-inline-crossover-pair-100-hz-high-pass-rca--266-274 I haven't tried it myself, but it's the only quick and dirty solution for those without AV receivers or Crown amps with built in DSP. Someone else in the forum recommended these.

 

[Krunok]

I am. Without a crossover you have 2 different slopes, so you cannot get correct summed output from the system, in most cases.

Global DSP can fix it, and some subs may be able to setup to fit their output to the mains, but if you have this level of control it's best to take the strain of the mains as well.

I believe that, generally speaking, proper sub(s) integration pretty much cannot be done properly without global DSP. And in that case I agree with you, taking strain of the mains at least a little is certainly beneficial. I also think that in scenario with only one sub it might be beneficiary to let sub overlap with mains, say in the 50Hz-90Hz (or even higher if sub can take it) so that mains can help that one sub fight the room modes. This scenario of course assumes mains are good to play comfortably down to 50Hz.

 

[Thomas_A]

I recently decided to insert the port plugs on my Monitor Audio Bronze BR2 stand-mounted speakers to decide if they sounded better that way than they do with the ports left open. (In the past, I did the same with an old pair of Krell K.5s I have lying around.)

My subjective (so, take it in that spirit) impression has been that they sound significantly better. I had to reset my subwoofer to pick up the increased bass slack, and, no, I have no DBTs to share. Still, I prefer the sound so far.

Anyone doing the same out there?

To match main/sub speakers e.g. with the 12/24 THX filter @ 80 Hz, you need to have a acoustic slope of the mains that is 12 dB/octave and -3 dB around 80 Hz. Plugging the port of a speaker may help to get there, but you need to measure the near field response of the top speakers to know how it looks. Then adjust the crossover point to match the slope of the mains.