Here are a number of threads at my site where the concept of “Rightsizing from extreme systems....” is pitched. I looked into the “second” systems not because I was interested in “different sound”. In fact I insist that multiple playbacks in the same listening room is in away a declaration of system owner’s Moronity. My interest in second playback is purely utilitarian. Macondo and Melquiades do well but they big, hot, and demanding. The amp need to be warmed up and so on… it is always nice to have a small scale SS driver playback that instantly or always, that is cool running and not too finicky. From a different perceive, I would like to use the sores that I have – so the none-fastidious second playback much be driven from the same preamp as the rest of my system. For instance: I run my Rohde & Schwarz Tuner  all time - 24/7,  and listing current and upcoming programming sometimes I would like turn the big Macondo on and sometimes I have no needs on interest…

Back to my Photography live we used studio flashes with pilot lights. The pilot lights were connected to the same dividers as the strop bulbs, use the same reflectors and if the flashes were made by serious companies then the pilot lights also very accurately to model and predict the character of the lightning that the given set of the lights would produce when the flashes go off. In fact in some case I preferred to shot just with pilot lights if I need a long exposure and was able to handle the color temperature… but it would be a separate subject…

So, looking at the way how I us my playback I wonder: why our large and extended installations might not include options for Pilot sound souses. If we presume that our main systems are installed at the best locations in our rooms then why do not incorporate into our mains systems the provisions for a small and perhaps crapy “summer monitors”? For instance is I design the Macondo Frame not I would incorporate into the frame a provision for building in a few direct radiators drivers. Let say a pair of 5” ported midbass drivers in MTM configuration, where the MTM’s tweeter sits right behind the Macondo’s Water Drop. I am not planning to do any change to Macondo but conceptually I think it is very interesting and beneficial idea – to have a good and bid system with imbedded option to do run it with “less blood”. In the case of 12 channels multi-amped Macondo it is particularly a blessing… Since I am a first to my knowledge who propose this concept I would like to name the notion and MiniMe systems (courtesy to Austin Powers movies)

Interesting that the MiniMe sections of big systems should not necessary to be a crapy sounding systems. With knows dose of creativity, talent and skills the MiniMe systems might be good. It is like design of motorcycles engine – the specific limitations of the motorcycle architecture forces the engineers to implement in motorcycle engine some decisions that would make big cars to envy…

I certainly do not try to propose that the MiniMe sections need to match or mimic the sound character of big system the MiniMe is implanted into. But it might be good enough to let a person do not have any another speaker in his/her room and would make the use of the main installation much more accommodatable for ordinary and non-demanding (did I say non-air-conditioned) listening.

Bob,

Yes, the variants are multiple but the key I feel might be the following: smaller size, less reliance to baffled, smaller size. Or yes, did I mention the smaller size?

The thing that led me to think about the MiniMe incorporation was my recent discovery of 4” driver that in practically no enclosure (1/8 cu. ft.) does very nice “full-range” sound and being combined with a regular tweeter it does remarkably good. Well, I would not call it “remarkably good” in absolute since but it does reputable sound, much better than most of high end speakers (I am not kidding) and the driver cost $11 (I am not divulging at this point what it is). So, playing this driver in 6” tall speaker and loving the result I was wondering why I can’t stick the drive and the tweeter in my Macondo frame – it need practically no enclosure…  BTW, it is interesting that you mention the “PHL 1120's with a proper ribbon”. I did ordered 2 days ago a “proper ribbon” for my none-integrated all-time-on MiniMe system. So, might be I will be using something similar to what you proposed. I just would like to drive it into a smaller package possible but I also need it to tolerate a lot of volume abuse.

The point is that I very much like idea to have solid state A/B cool rums amp that drive the MiniMe installation that is completely integrated with Macondo. Then, if I wish, I can only by flipping one switch to I can defeat the MiniMe system and turn the big system on. It is what I have no but my monitors are free-standing and not incorporated with Macondo. If I design the Macondo not from scratch then I would put somehow the MiniMe provision in the Macondo’s Frame.

The Cat

Many years back, when I first went to try using more than one set of speakers in the same room, I was told that the "idle" drivers would have a negative aural effect on the drivers being listened to.  Naturally, I went ahead and did it anyway.  And the guy was right; it did suck power at different frequencies, almost like phase cancellation.

Is this a "who cares" situation, or might this matter, if it also proves true in your case?


Best regards,
Paul S

Well, the license of think this way was given to me by one mini-monitor that I found to sound “promising” for the objectives that I would like to achieve. In fact not even the monitor itself but the bass driver, the drive that in a way was unique characteristics. When I said unique I did not mean exceptional but rather no common – I would not at this point to comment about the driver’s quality of sound. So, I figured that 4-8 of those drivers combined with “slowed” ribbon will do for me.

I don’t think that this is a conversation about my desire to me a ported speaker to sound better – it is not my objective and you would hardly find a more jaded opponent of port enclosure then me. Bu any tool and any solution is applicable only  within a scope of a given requirements and the requirement for my Macondo MiniMe is very simple: to get more or less OK sound with smallest footprint possible and capable to care high power, let was 100W.

So, I have to prototype and it looks like it might work with those drivers that I found. Hey it even sounds very nice, or put in this way – promising. Since it will be a tall enclosure (magnetically attached to the Macondo’s frame) I wonder where to locate the posts. In the image below depicts the question: shell it be red, green or yellow approach. I also have no clue how deep shell be the point of port’s end into the enclosure, among many other things…

Thanks, LBJ

It is useful. I had also an idea to have a port mounted on removable plate in order to have the port side changed. I also, very much inclined for the yellow version, even my reasons are very none objective and I based my superstitions on the fact that a few commercial ported speakers that I do not hate had ports under the bottom (like older version of Edddelons).  Do you know what the depth of the port in the chassis responsible for?

I have a crazy ides but I do not know it I go for it. In yellow configuration I might have pipe with inner diameter of 1.25” welded from top port to bottom port. The pipe will be though the speaker, keeping the speaker sealed. The pipe will have spiral cuts. Inside this pipe I will have another pipe with outer diameter of 1.25” with similar spiral cuts. Now, turning on the coupling thread the inner pipe relative to the outer pipe I will have change the virtual port opening…  I am sure it will do the venting effect but I have no idea how the geometry of the initial escape of pressure affect sound. It very much possible that the profile of the port exist’s not the port’s entry is important and if it is the case then my idea will work and let me to fine tune the port by ears.

That is certainly a new idea.  Unless it is really easy to take it out and start over, I would not do it.  I just have no idea whether or not it will work without making noise.  I have always just used mathematical calculations for ported speakers, so anything I write here should be taken at face value.  http://graph.flexunits.com:8080/index.htm may be a helpful calculator for you to play with. 

If you had one pipe with an inner diameter at 1.25" and another pipe with an outer diameter of 1.25", you could cut off the ends at a 45 degree angle.  The theoretical port length should be at the mid point of the angle.  The inner pipe could then be turned to very finely tune the port.  I hope this is clearer than it sounds.  Check out the attachment.  I think that this might be the best way to finely adjust the length of the port while minimizing the risk of unwanted noise.

Regards,
LBJ

Lbjefferies7 wrote:

I just have no idea whether or not it will work without making noise.

You might find it can sound better if each driver has its own box and its own port (PITA, I know).  I have had better success by tuning the port +/- below audibility and then using some whimpy foam to partially block the "too large" opening, as opposed to making the inlet smaller.

Does it defeat your purposes (in terms of efficiency) to use minimal stuffing or an internal hanging "curtain" in any of the boxes?  Obviously this gives the option for smaller boxes, albeit at the expense of some efficiency.

Basically, the more you try to do with/get from the port, the more of it you'll hear.

I've only tried steel with very small, sealed nearfield boxes, but it needs well-bonded, effective damping.  I used acrylic-modified stone mortar and felt in my DEBZs, which are 1 1/4" plywood.  The thing with steel is, it seems so "severe" and "unforgiving", certainly a great, grand, expensive PITA to build and to modify.

BTW, I agree that the math is a great place to start.

Best regards,
Paul S

The port should use the inner surface of the cabinet walls as an extension:



 

Rgs,

Petar

Petar,

What you say doe make sense but I think I am in a different environment. I use the driver about what I have no knowledge at all, I do not even know at this point where to source them. I will drive the thing lower then the drivers resonance frequency, if fact I will drive them as low as I can. I would agree that it ming and most probably will puff up bass and kill the lover MF. I will deal with it when I get there, but this Pilot speaker do not get objective to be a great speaker but rather “sufficient” speaker.

I like the idea of horn-like opening of the port –it shell create more smooth transformation of pressure. I was thinking about it myself as well as I have seen a few companies do it. Your idea of multiple small ports very much attracts me and I might very much go for it. I do not know how it effect sound by the fact of being multiple but to have 8 smaller ports on each side would allow to plug a few ports by ears if I found it necessary – sort of playing a flute on the ports  (valves) and tune the speaker to what it shell be –very slick idea and very much affinity with my level of insanity. The multiple small ports would be much easier to implement then my idea of reviving pipes….

There is two subjects that I do not know. Could you or anybody ease, tell me the different (in behavior of sound) between those versions:

Romy,

Regarding your first illustration:

Some time ago I intentionally made two different boxes for my ScanSpeak drivers to see what will happen, because I do not believe in theories and trust only to my ears. The boxes had exactly the same internal volume and front baffle width, so the only difference was in their actual proportions (height and depth). The first one was very tall and very shallow, the second one was little in height but very deep.

There was HUGE difference in sound. The deep box sounded much more articulated and with ease at the dynamic peaks. The improvement in sound was most remarkable in the upper range of the driver. The only reasonable explanation I have for that is that the back wave form the driver bounce back to the cone and interfere with the front fired wave, adding delayed signal with high amplitude. If the back wall is very far from the driver’s diaphragm, the energy of the reflected wave is very low thus the sound is more clear and better defined. In comparison the sound of the shallow box was some kind of polluted at MF, loosing definition and dynamics (micro and macro), the midbass was quite excessive and unlistenable, although SS is quite nice driver.

So I think the depth of your box is of much greater importance than the exact location of the ports at the bottom and I definitely think the design “B” is going to have better sound.

My thoughts about your second illustration:

I’m not sure if my interpretation of the picture is right, but the port of speaker “B” seem veeery long to me. That means the tuning will be extremely low and the acoustic system should behave more like sealed box rather than typical bassreflex design. It is true if you tune it below approximately 20Hz but I hardly see any sound benefits from this kind of bass loading. The longer the port is, the lower the Fb will be and vice-versa (if the port area is the same). What is your motivation to use so long port?

haralanov wrote:

Some time ago I intentionally made two different boxes for my ScanSpeak drivers to see what will happen, because I do not believe in theories and trust only to my ears. The boxes had exactly the same internal volume and front baffle width, so the only difference was in their actual proportions (height and depth). The first one was very tall and very shallow, the second one was little in height but very deep. There was HUGE difference in sound. The deep box sounded much more articulated and with ease at the dynamic peaks. The improvement in sound was most remarkable in the upper range of the driver. The only reasonable explanation I have for that is that the back wave form the driver bounce back to the cone and interfere with the front fired wave, adding delayed signal with high amplitude. If the back wall is very far from the driver’s diaphragm, the energy of the reflected wave is very low thus the sound is more clear and better defined. In comparison the sound of the shallow box was some kind of polluted at MF, loosing definition and dynamics (micro and macro), the midbass was quite excessive and unlistenable, although SS is quite nice driver. So I think the depth of your box is of much greater importance than the exact location of the ports at the bottom and I definitely think the design “B” is going to have better sound.

I am sorry, you might mistyped. You meant to say the design “A” is going to have better sound, do you? The design “A”  has more deep box.

haralanov wrote:

My thoughts about your second illustration: I’m not sure if my interpretation of the picture is right, but the port of speaker “B” seem veeery long to me. That means the tuning will be extremely low and the acoustic system should behave more like sealed box rather than typical bassreflex design. It is true if you tune it below approximately 20Hz but I hardly see any sound benefits from this kind of bass loading. The longer the port is, the lower the Fb will be and vice-versa (if the port area is the same). What is your motivation to use so long port?

Well, I have no other motivation then juts to make it comprehensible that the ports lengths are different. I certainly am not planning to go it so long, but I was wondering how the length of the port and the most important the proximity of it to boundary affects sound. I might have the same port diameter and the same length but the port might stat from an open middle of the box vs. the port might start a few mm from an opposite wall. That what I was trying to depict. So, Petar, what would please to comment on it. Also, if the exit of the pot is important for pressure synchronization (you use horn-like profile and I like it) then can we presume that enters of the how might be benefited from gentile pressure transformation? Would in such case something like this to look overly ridicules?

Romy the Cat wrote:

...but I was wondering how the length of the port and the most important the proximity of it to boundary affects sound.

Lbjefferies7 wrote:

Now, as for your drawing of the exaggerated port flaires, it is excessive.  A port is not a horn and, from an engineering standpoint, I treat them very differently.  A port is a resonator.

Oh, sure I understand it and drew it excessively solely for the sake of illustration. I have see a few companies did the exit of the horn in semi-horn profile, so that lead to a question of the entrance of the Helmholtz resonator might be benefited from the semi-horn shape.

Lbjefferies7 wrote:

Using ports as anti-compression devices is just plain bogus, in my estimation.  Above the port's tuning frequency (Fb), the enclosure acts just as a large sealed enclosure.  Below the Fb, it acts as a quasi-infinite baffle system.  When the driver reproduces the Fb, the port "opens up" at the Helmholtz frequency...where the air masses in the box and in the port reach a "balance" where the output of the port is 365 degrees out of phase with the driver.  The responces of each resonator combine and create a greater overall response.  By tuning the port, the port's output can extend the sealed response of the acoustic system.  This is how I understand it, at least.

Yes, it is a perfect explanation and it is how I understand it but read below…

Lbjefferies7 wrote:

Now, Petar is spot on when he says that the Fb must not be below the resonant frequency (Fs) of the driver.  If it is, you will certainly get a horribly disgusting cone-flapping sound and may just fry your drivers.  The vision of murder will be dancing in your head...like sugarplums on steroids!

Ok, this is exactly where I am a lost. As long we keep the port’s resonance below driver’s resonance then I agree that we are at more or less save ground. Even I - the person who never experimented with poet in my live- have written about it at in past. However, if we accept this premise then we defeat the entire purpose of using ports. Of cause we would like to have LF EQ on the enclosure in compare to a sealed solution. Of cause we would like to drive the port’s resonance below the driver/enclosure resonance to get more bass out of the situation, without use of ultra low Fs driver and increasing the size of the box. Or cause we would have a sever driver reactance when the resonances “meet”. Aren’t they all the ideas of port use and isn’t it how it works in all bass reflex loudspeakers. I was under presumption that by embracing the horn idea we are by default let the amplification, filtration and other thighs to deal with driver “comforting” during the cone-flapping… If we keep the Fb above the Fs then why do we need to a port to begin with?

Romy the Cat wrote:

Of cause we would like to drive the port’s resonance below the driver/enclosure resonance to get more bass out of the situation, without use of ultra low Fs driver and increasing the size of the box. Or cause we would have a sever driver reactance when the resonances “meet”. Aren’t they all the ideas of port use and isn’t it how it works in all bass reflex loudspeakers. I was under presumption that by embracing the horn idea we are by default let the amplification, filtration and other thighs to deal with driver “comforting” during the cone-flapping… If we keep the Fb above the Fs then why do we need to a port to begin with?