Jump to content

Plugging rear speaker ports


Recommended Posts

894639829_ScreenShot2019-05-07at7_48_42PM.thumb.png.6d55c7c733e5f44077090b790f37ccdf.pngI have a pair of RF-83 which are rated down to 29 htz, and have serious bass peaks in my room at 45 and 70. In my attempts to solve this issue I have played with tone controls, plugging ports in various combinations, fidgeted with position and other tweaks.  The best solution I have found, that only modifies the bass 1000 htz down, is plugging 2 of the 3 ports in these speakers, the bottom 2 to be exact. When doing this I lower those room peaks but to my surprise, I gained bass from the 32.5 htz and lower. Sounds much better to my ears.

 

I am confident in my measurements, I did them like 20 different times, different days, and they are consistent.

 

Seems like a good solution with no apparent down side.  Am I missing something????

 

attached image with 2 curves,  one normal response and one with 2 ports plugged.

 

  • Like 2
Link to comment
Share on other sites

"Sounds much better to my ears. I am confident in my measurements, I did them like 20 different times, different days, and they are consistent.

 

This is all that matters really. Why are you seeking affirmation here on what pleases you? What you are doing is offsetting room gain in the lower bass region, in your specific room. A totally flat sound reproduction across the frequency spectrum 20-20khz. I could go on a long diatribe on sealed vs bass reflex loudspeakers.

 

BR enhances the bass, by utilizing the air movement/sound generation on both sides of the transducer cone. One could theorize that this is not entirely accurate, the rear rebound movement of the transducer cone is an echo of the original signal. Some concur with this assessment. BR also impacts the latency of bass reproduction, critical say in a cello recording/reproduction. Or a pipe organ. Depends on the music genre, and how the music/vocals were originally reproduced and recorded. There are very few sealed home loudspeakers offered new these days, if any. The evolution of BR speaker design over the years is better bass, and more of it imo. Acoustic Research (marketed as air suspension design) made them popular in the later 1950s and into the 60s. My bro in law has a set, still has them sitting high on a shelf unused currently. My old large Advents many years ago were sealed, and sounded really good. I went looking for sealed loudspeakers, couldn't find any large floorstanding models, and recently purchased a new set of Cornwall iii (bass reflex cab) go figure. But I like my bass hot/enhanced most times. Just my preference, flat Audyssey doesn't work for me. Attend a live rock concert, the bass isn't flat by any means. Now for acoustic strings and delicate music (classical and jazz), I dial the bass down big time, or opt for no sub at all. I have a SVS-SB3000 in conjunction with my CWs. Sometimes I like to rattle the windows or paintings on my walls. BR loudspeakers with a sealed 13" 1000 watt subwoofer.....oh my.

 

If I had my choice, I would have purchased large floorstanding loudspeakers of a sealed design, with a 15-18" woofer transducer (or two) but nobody makes those. (Shoot, I could only find 3 offerings with a 15" woofer, Klipsch, BIC, and Cerwin Vega, all BR)  Sure you could have them custom made but I have limited/finite resources. The CWs were pushing it but they are American made with gorgeous Indian Rosewood veneer, and sound pretty good. And I think I got a pretty good deal on them.

 

At the end of the day its what is pleasing to your ears, or mine at my house. Our tastes and preferences may not be the same. 

 

History of Acoustic Research Loudspeakers

 

Pros and Cons of bass reflex loudspeaker design article on Wikipedia

Link to comment
Share on other sites

Oh and that's 29-21,000 hertz, + or - 3 db. (plus or minus 3 db as most all loudspeakers are rated by their manufacturer) 6 db is a massive deviation in sound levels if you are seeking a truly flat across the board sound reproduction range. 

  • Like 1
Link to comment
Share on other sites

11 hours ago, Carlosrs said:

 

 

I am confident in my measurements, I did them like 20 different times, different days, and they are consistent.

 

Seems like a good solution with no apparent down side.  Am I missing something????

 

 

A lot of speaker vendors provide plugs for their speakers to aid in placement because the speakers can, with certain placement, be bass heavy.  Only down side is less bass. 🙂  Oops, you want to reduce the bass....

Link to comment
Share on other sites

1 hour ago, polizzio said:

"Sounds much better to my ears. I am confident in my measurements, I did them like 20 different times, different days, and they are consistent.

 

This is all that matters really. Why are you seeking affirmation here on what pleases you? What you are doing is offsetting room gain in the lower bass region, in your specific room. A totally flat sound reproduction across the frequency spectrum 20-20khz. I could go on a long diatribe on sealed vs bass reflex loudspeakers.

 

BR enhances the bass, by utilizing the air movement/sound generation on both sides of the transducer cone. One could theorize that this is not entirely accurate, the rear rebound movement of the transducer cone is an echo of the original signal. Some concur with this assessment. BR also impacts the latency of bass reproduction, critical say in a cello recording/reproduction. Or a pipe organ. Depends on the music genre, and how the music/vocals were originally reproduced and recorded. There are very few sealed home loudspeakers offered new these days, if any. The evolution of BR speaker design over the years is better bass, and more of it imo. Acoustic Research (marketed as air suspension design) made them popular in the later 1950s and into the 60s. My bro in law has a set, still has them sitting high on a shelf unused currently. My old large Advents many years ago were sealed, and sounded really good. I went looking for sealed loudspeakers, couldn't find any large floorstanding models, and recently purchased a new set of Cornwall iii (bass reflex cab) go figure. But I like my bass hot/enhanced most times. Just my preference, flat Audyssey doesn't work for me. Attend a live rock concert, the bass isn't flat by any means. Now for acoustic strings and delicate music (classical and jazz), I dial the bass down big time, or opt for no sub at all. I have a SVS-SB3000 in conjunction with my CWs. Sometimes I like to rattle the windows or paintings on my walls. BR loudspeakers with a sealed 13" 1000 watt subwoofer.....oh my.

 

If I had my choice, I would have purchased large floorstanding loudspeakers of a sealed design, with a 15-18" woofer transducer (or two) but nobody makes those. (Shoot, I could only find 3 offerings with a 15" woofer, Klipsch, BIC, and Cerwin Vega, all BR)  Sure you could have them custom made but I have limited/finite resources. The CWs were pushing it but they are American made with gorgeous Indian Rosewood veneer, and sound pretty good. And I think I got a pretty good deal on them.

 

At the end of the day its what is pleasing to your ears, or mine at my house. Our tastes and preferences may not be the same. 

 

History of Acoustic Research Loudspeakers

 

Pros and Cons of bass reflex loudspeaker design article on Wikipedia

I agreed with you wholeheartedly that the right sound could only be defined by my own ears, too personal.  Congrats on this cornwalls iii, they are incredible speakers.  I have in my office system, which has extensive acoustic treatment, a pair of Forte II with upgraded Crites caps and crossover cables, sealed all possible air leaks and added 2.5 oz of weight to the passive radiator.  These powered by a Sunfire Ultimate Receiver just sound incredible!!!

 

I love sealed subs, I believe they give me better quality bass that the ported brothers.

 

Thank you for for the pros and cons of BR design, there is very useful info in there to better understand the general principles.  My confusion is why I gained bass below 32.5 htz??? Seems opposite of what I expected??

Link to comment
Share on other sites

1 hour ago, pzannucci said:

A lot of speaker vendors provide plugs for their speakers to aid in placement because the speakers can, with certain placement, be bass heavy.  Only down side is less bass. 🙂  Oops, you want to reduce the bass....

It seems that any combination of plugs used ONLY affects below 100 Htz. I am still getting a hotter bass than flat, but just below exciting the room to become boomy, better bass.  And actually MORE bass below 32.5 htz🤔

  • Like 2
Link to comment
Share on other sites

1 hour ago, polizzio said:

the rear rebound movement of the transducer cone is an echo of the original signal. Some concur with this assessment. 

 

Not me.  It's not an echo in any way, shape, or form.  It's part and parcel of the "original signal".  Without it there'd be no generation of the signal.

 

There are two detriments to using a ported enclosure.  One is the alteration of the timing.  It's a delayed reaction coming from the port.  Not the end of the world by any means, especially at the frequencies that are in play.  The other is that the response of the system loses output at a faster rate as the frequencies decrease.  Neither has to be a show-stopper, and as in most things in real life, the trade-offs are often worth it.

 

2 hours ago, polizzio said:

If I had my choice, I would have purchased large floorstanding loudspeakers of a sealed design, with a 15-18" woofer transducer (or two) but nobody makes those. (Shoot, I could only find 3 offerings with a 15" woofer, Klipsch, BIC, and Cerwin Vega, all BR)  Sure you could have them custom made but I have limited/finite resources. The CWs were pushing it but they are American made with gorgeous Indian Rosewood veneer, and sound pretty good.

 

Have you tried blocking the ports on your Cornwalls?

Link to comment
Share on other sites

46 minutes ago, Carlosrs said:

And actually MORE bass below 32.5 htz

 

Because the rate of decay in output is a shallower slope now as the frequency decreases compared to fully-open ports.  It's acting more like a sealed box.

Link to comment
Share on other sites

1 hour ago, Carlosrs said:

I agreed with you wholeheartedly that the right sound could only be defined by my own ears, too personal.  Congrats on this cornwalls iii, they are incredible speakers.  I have in my office system, which has extensive acoustic treatment, a pair of Forte II with upgraded Crites caps and crossover cables, sealed all possible air leaks and added 2.5 oz of weight to the passive radiator.  These powered by a Sunfire Ultimate Receiver just sound incredible!!!

 

I love sealed subs, I believe they give me better quality bass that the ported brothers.

 

Thank you for for the pros and cons of BR design, there is very useful info in there to better understand the general principles.  My confusion is why I gained bass below 32.5 htz??? Seems opposite of what I expected??

 

I believe you Carlos about your tuned Forte IIs. Clearly you have very good hearing and know what you are striving for. I had ported subs before and if one really understands the dynamics of the transducer and its reproduction, they create echos to generate bass volume, or tune the cabinet/system to achieve enhanced very low frequency production. Take for example a low cost BIC vented sub...then everybody should just buy one of those (or multiples of)and save their cash for other improvements. Most guys go for vented subs for home theater, maximum impact/slam. And you can tune the cab for say 20 hz enhanced generation. One can do the same with sealed, just need bigger transducers or more of them, and more amp power. Its sealed subs for me going forward. They have some firms building and marketing some massive output subs today. Seaton, JTR, Rythmik, PSA to name a  few. And those giant subs that Norwegian builds. 21" transducers....sweet!

 

I'm 61 and my hearing is damaged from loud music ,concerts, drag racing, engines with open headers, and shooting. I cannot hear over 5khz without some major boost. I make every attempt to conserve my hearing now, and for the last 15 years. Ear plugs or muffs are my regular friends. I wear earplugs to mow my yard and most all power tool operation :) 

 

As for the increase in bass @32 hz after plugging 2 of the ports, my best guess would be you effectively re-tuned the cabinet in doing so, from its original design. Like Glen stated above, way more like a sealed cab now. Big time change @ 25hz. You def improved the overall response with your tuning. Well done sir.

Edited by polizzio
  • Like 1
Link to comment
Share on other sites

I had similar problems with my pair of RF42 II.

Plugging the rear ports only killed the bass that is very shy in small stand mounters anyhow. Of course this is not the case with 83s.

Changing the speaker wires between upper and lower set of connection points at the back of the speakers also made a change. On the upper connectors the bass was a bit milder/subdued.

I noticed the most improvement in bass by changing speakers position in the room and taming the early reflections in front of them.

  • Like 1
Link to comment
Share on other sites

46 minutes ago, glens said:

 

Not me.  It's not an echo in any way, shape, or form.  It's part and parcel of the "original signal".  Without it there'd be no generation of the signal.

 

Have you tried blocking the ports on your Cornwalls?

 

Should have clarified my origin statement. In a vented cab, its effectively an echo. And in a sealed loudspeaker or sub, the signal is produced, it just doesn't utilize the air pressure/movement from the backside of the cone to enhance bass output. Maybe some echo from cone bounce in a sealed, but not direct output like a vented. In every subwoofer with same transducer and amp power utilized, the vented cab output is always greater output than a sealed, in decibels. Josh Ricci over at data-bass has built many cabinet types and derivatives using the same transducer and amp, and extensively recorded detailed testing using precision equipment. He also writes/contributes to a couple on line sites/magazines. The tuned horn subwoofer holds most of the overall highest output records at data-bass. Some hit 134 db. And Josh has great info/explanation/testing on sub distortion levels at high output. Mr. Ricci knows his stuff!

 

Perhaps one day I might try some foam plugs but no time soon. I haven't even removed one of the grills on my CWs. I did remove the gold/black PWK emblems I stuck on there. I could cross the CWs and the SVS sub @100 hz  respectively, so I mostly have sealed low bass. Right now I re-set speaker sizes and crossover to CWs large (full range) and sub low pass @ 100 hz. Double bass, I love it. Awesome while watching tv last night or an action movie blu ray like Live, Die, Repeat. Those freakin helicopters crashing feel and sound like they are in my LR. Flip to straight 2 channel AVR setting for Enya or Alexandra Porat covers and sub falls out of the lineup.

  • Like 1
Link to comment
Share on other sites

19 minutes ago, Marvel said:

 

This also worked to lower the tuning of the box.

 

Yes it did, they feel with more aplomb. That 15' passive radiator is magical, and it sounds alive even at low volumes which is just great!!! Some speakers you have to put the volume higher for them to shine, these Fortes are always "ON" at any volume.

Link to comment
Share on other sites

1 hour ago, polizzio said:

 

I believe you Carlos about your tuned Forte IIs. Clearly you have very good hearing and know what you are striving for. I had ported subs before and if one really understands the dynamics of the transducer and its reproduction, they create echos to generate bass volume, or tune the cabinet/system to achieve enhanced very low frequency production. Take for example a low cost BIC vented sub...then everybody should just buy one of those (or multiples of)and save their cash for other improvements. Most guys go for vented subs for home theater, maximum impact/slam. And you can tune the cab for say 20 hz enhanced generation. One can do the same with sealed, just need bigger transducers or more of them, and more amp power. Its sealed subs for me going forward. They have some firms building and marketing some massive output subs today. Seaton, JTR, Rythmik, PSA to name a  few. And those giant subs that Norwegian builds. 21" transducers....sweet!

 

I'm 61 and my hearing is damaged from loud music ,concerts, drag racing, engines with open headers, and shooting. I cannot hear over 5khz without some major boost. I make every attempt to conserve my hearing now, and for the last 15 years. Ear plugs or muffs are my regular friends. I wear earplugs to mow my yard and most all power tool operation :) 

 

As for the increase in bass @32 hz after plugging 2 of the ports, my best guess would be you effectively re-tuned the cabinet in doing so, from its original design. Like Glen stated above, way more like a sealed cab now. Big time change @ 25hz. You def improved the overall response with your tuning. Well done sir.

I like sealed subs so much I have 5.  An RSW-15 and 2 RSW-10D stacked in my HT.  Just bought two more and are out to service in Edwards Electronics and should receive them in a few weeks.  I still don't know where to use them, but I got them and they are difficult to come by, jajajaja!!! Both of my 2 channel systems sound great how they are, maybe I will experiment with a 2.2 system and see how it goes.

 

Thank you polizzio!!🙏

  • Like 1
Link to comment
Share on other sites

14 minutes ago, Carlosrs said:

2 RSW-10D stacked in my HT.  Just bought two more and are out to service in Edwards Electronics and should receive them in a few weeks.  

I still need to do that with my RSW-10d.  Let me get it straight, I remove the amp and power cord input sections and send them in?

 

Bill

Link to comment
Share on other sites

7 minutes ago, willland said:

I still need to do that with my RSW-10d.  Let me get it straight, I remove the amp and power cord input sections and send them in?

 

Bill

Hey willand. Yes, remove amp, cables and the two triangle controls/inputs on the outside of the box.  The screen is not necessary, they have screens there to test.

Link to comment
Share on other sites

6 hours ago, JohnA said:

The only thing you've missed is port "chuffing", noise, at higher listening levels.  Have you tried plugging all 3? 

I have not heard port chuffing, but I don't play them very loud though.  Will experiment with all three ports plugged and see how they sound.  Maybe I can plug all three and fill in the lower bass region with dual RSW-10Ds??🤔

Link to comment
Share on other sites

So i mentioned the Data Bass website above and I just found out the website addy has changed. Actually a new and improved website (v2), with newer reviews. Below is the up to date hot link.

I'm quite sure some of you guys here will find the site informative and entertaining. 

 

https://data-bass.com/#/?_k=lpb4oa

 

Josh and JTR Speakers have been busy. JTR Orbit Shifter sub = 141 db @ 80 hz. 4000 watt amp. Oh my!

Edited by polizzio
Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...