To date in the few years that I have been on here, I posted plenty of pics of my construction skills, please don't insult with leaky boxes remark. One of my builds has been afloat for 8yrs now fishing commercially in the tropics and lived a category 5 cyclone without springing a leak. Please show some pics of your builds, I may get a reference as to what you consider a properly sealed
To me, a sealed sub feels like a dead instrument, I can't play it. Would you argue that I persist with an unplayable instrument?
To me, a sealed sub feels like a dead instrument, I can't play it. Would you argue that I persist with an unplayable instrument?
I put the amp under the lens. Can almost make out 2x 8392 class ab chips, maybe in bridge? This is for the stereo channels, the .1 looks like discrete class ab and the power supply is tracking for all. The manufacturer makes versions for Euro and higher end Asian cars too. Piece of paper prevents saying anything else on this
Randy…..let’s set some fundamentals……in order to create low frequency content, you NEED to move air. There‘s only three ways to accomplish this……surface area of transducer, excursion of transducer (xmax) and resonance. Your quest for a small system negates option one. Option two requires a driver with a robust suspension which reduces efficiency and requires high current. At your desired enclosure displacement, the equation no longer works other than exploiting resonance for deeper output. But resonant systems don’t function when the air in the enclosure is coupled to the driver…..it needs a seperate resonant chamber often referred to as a port quite incorrectly……the air within the enclosure does not exit the port as sound…….the ‘port’ is its own resonant chamber which amplifies sound at a specific frequency and nothing more…..port displacement cannot exceed enclosure volume.
Again….not sure where you’re going with ‘playing the instrument‘…..a sealed system driver will respond faster and with less delay and greater control of the cone upon input when compared to a resonant system. F3 is F3………ported rolls of at 24db per octave while sealed at 12db per octave…..it will play deeper if asked and if the suspension has the linear travel available. A high pass filter is helpful or necessary depending.
Again….not sure where you’re going with ‘playing the instrument‘…..a sealed system driver will respond faster and with less delay and greater control of the cone upon input when compared to a resonant system. F3 is F3………ported rolls of at 24db per octave while sealed at 12db per octave…..it will play deeper if asked and if the suspension has the linear travel available. A high pass filter is helpful or necessary depending.
Then I must be failing to understand the dayton 2x7 recommendation. How can it handle more power and move more air than the 450wrms 18mm xmax zr6 driver? The port was dropped in favour of a PR or two as such a small net volume models as poor TL in Hornresp
These basslines just doesn't sound right on sealed speakers. They are recorded with expectations of being played on reflex systems too and monitored using reflex systems
On the other hand, sealed does sound better with kick only genres with very little or no bassline
Difficult to explain, try plugging a bass into a sealed system and play "funky punannay", just doesn't sound and feel right
These basslines just doesn't sound right on sealed speakers. They are recorded with expectations of being played on reflex systems too and monitored using reflex systems
On the other hand, sealed does sound better with kick only genres with very little or no bassline
Man, I know you folks have been at this for a lot longer but this is getting ridicoulous. Did you actually check the ZR6 numbers and how it models with 4L cab volume in Winisd? Is this not moving enough air? I have been begging folks to help me understand how to read the results and thought I was learning and goiing well to come up with this result for a 4L @40hz tune box. Now you are telling me that I am not doing this right?
What is bad about this result for the ZR6 in 4L BR redone as a PR and why should the dayton bar unit in a sealed be considered instead of this result for a solid but tiny 40hz box. I thought I was absorbing well and modelling better but now you have confused the ef out of me man
Just for the sake of completeness: also sealed speakers are resonant, of course.
Ported/PR systems are higher order resonant systems, thus they have more low end output but also more group delay.
group delay also varies with the enclosure Q of sealed enclosures, by the way.
Sorry for the confusion, ….the little Dayton driver is just a sharing of info or as an option used in multiples with EQ.
When performing your modeling with such small enclosures designed for maximized performance, it’s very important to look at enclosure volume as NET volume. The DS driver you’re considering looks to displace about 1.5 liters. If I’m correct, you discarded the ported system to regain the volume displaced by the port in favor of PR? There will be some displacement there as well with the PR Chassis and added mass. A good rule of thumb is 2x the driver SD required for efficient PR performance. I know you have an overall gross max enclosure size you’re working with so……
My only area of contention was your subjective dislike of sealed systems compared to resonant…….hopefully I’ve effectively translated that to a point of understanding where the sealed system when properly designed will always be more accurate to the input signal.
When performing your modeling with such small enclosures designed for maximized performance, it’s very important to look at enclosure volume as NET volume. The DS driver you’re considering looks to displace about 1.5 liters. If I’m correct, you discarded the ported system to regain the volume displaced by the port in favor of PR? There will be some displacement there as well with the PR Chassis and added mass. A good rule of thumb is 2x the driver SD required for efficient PR performance. I know you have an overall gross max enclosure size you’re working with so……
My only area of contention was your subjective dislike of sealed systems compared to resonant…….hopefully I’ve effectively translated that to a point of understanding where the sealed system when properly designed will always be more accurate to the input signal.
Confused again man, do I not appear to have a firm handle on NET, GROSS internal and eternal? Drawings show that everything is aligning with the drivers displacement, material thickness and its displacement, driver compartment volume, port volume, aux compartment volumes and so on
Would really like to find out how I am falling short in correctly using displacement
Unfortunately, you have failed to convey your meaning. I'll try a bit more on my stance why a sealed system is not high fidelity
1 - is the objective not to stay true to the tones and depths that the recording engineer bopped to?
2 - a search of studio monitor speakers results in mostly reflex based monitors and subs
3 - When the engineer is compiling a recording, there is a reflex based resonant system between the recording and his ears doing the electronic to mech/acoustic conversion
4 - the material recorded does not contain that effect that the engineer is bopping to
5 - You are not monitoring with a similar effector. Thus, the sound that you are hearing is not what the engineer bopped to and untrue to the music. Not Hi-Fi
6 - send your sealed a test tone, and it will be truer than a reflex system. So that is your stance, "audiophile" fidelity thus means effecting down what the engineer intended, and we should build our speakers to effect down? Incorrect!
With the above 6 points, this noob declares sealed systems as not accurate for listening to music and making music. Teach me why these points are incorrect please
Back to tiny40s
I am quite keen to try some of those RBM things. Does anyone have any experience with those. It will be very expensive shipping from parts express to here, prolly much more than the driver itself. It's a gamble that I am hesitant to take
My whole need started with having a very small all in one system to listen to and play along with at late night, and doesn't need to be loud. Max ability doesn't have to be more than 70db. Just needs to be audibly flat to 40hz which will need a loudness comp for this and lower listening levels
So far the ZR6 looks to be the champ at this as it looks like it will be quite powerful in output in the target net 4L. But I don't need this much output for what I am trying to make. Just enough output to be audibly flat is the requirement as it will be battery powered as well using a power tool battery pack
I am quite keen to try some of those RBM things. Does anyone have any experience with those. It will be very expensive shipping from parts express to here, prolly much more than the driver itself. It's a gamble that I am hesitant to take
My whole need started with having a very small all in one system to listen to and play along with at late night, and doesn't need to be loud. Max ability doesn't have to be more than 70db. Just needs to be audibly flat to 40hz which will need a loudness comp for this and lower listening levels
So far the ZR6 looks to be the champ at this as it looks like it will be quite powerful in output in the target net 4L. But I don't need this much output for what I am trying to make. Just enough output to be audibly flat is the requirement as it will be battery powered as well using a power tool battery pack
Art, that might be louder than what I need for this one. I wouldn't mind having that loudness potential, but wondering if a smaller system would be more efficient for battery life and if an audible 40hz can be pulled out of a less extreme driver
In some mathematical sense this is probably correct though the word "NEVER" is an over broad statement. You could have a very "tight" low-Q sealed box versus some boomy monstrosity (looking at YOU SAS Bazooka, barf!). But you could also have a high-Q sealed box versus a slow-rolloff "undertuned" ported box, the ported box could well sound better. Especially if we really open things up and compare apples to oranges, for instance the high Q sealed box with a high resonance frequency versus if the "undertuned" box was tuned quite low.
Even in the sealed case things are not so obvious-I was startled when in another thread someone posted tone burst waveforms showing that a "tight" Q=0.5 sealed box had actually worse overall transient response (choking off the initial rise), and Q=1 was not so bad actually. (This was IIRC presuming the resonance frequency was the same, which means this is NOT using the same driver in different size boxes).
This whole area of what really indicates if something will sound "boomy" (aside from the room ha ha ha) is an area that I don't consider well defined. I'm not aware of a tool that lets you look at tone bursts-the simulation I mention was done via some tedious process in Excel. I like tone bursts because they are quite visual, as opposed to merely examining a response curve or looking at a group delay curve.
Oh I supposed "accuracy" should also encompass distortion, which can be lower over some frequency range with the ported box due to lower excursion.
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A bunch o' random observations:
- "Audible" is a key and big word here. From the equal loudness contours in @weltersys post #74, it seems 40 Hz would be audible at 60some dB. But if you are playing at I think you said 70 dB, for the bass to sound correctly loud you'd follow the 70 Hz contour up from the midrange and find you'd need ≈ 106 dB. How far away are you listening? If 2 m that means like 112 dB from the driver, if 3m then like 116 dB if I'm doing the math right in my head. (That's ignoring some amount of room gain).
- More information is in this paywalled thing https://www.aes.org/e-lib/online/browse.cfm?elib=5147
- From a driver small enough to work in a 4L box, or a port of small enough area to tune that box down to 40 Hz, I cannot imagine it is possible to move/flow enough air. I gotta do some stuff for work so sorry I cop out no time to do the calculations right now. Well OK from an online calculator it says a 6" driver would have a 76mm Xmax
oops: one direction I presume). http://www.baudline.com/erik/bass/xmaxer.html - A port functions as a kind of "plug" mass of air on the "spring" that the air in the box forms. Just like a suspension on a car, or jumping on a trampoline, this resonates at a certain frequency. A passive radiator substitutes cone mass for air mass, with the advantage of maybe not taking up so much room inside the enclosure. In tiny boxes sometimes you can realize a lower tuning than is physically possible with a port of sufficient cross section to not compress/choke and distort. A disadvantage can be less linearity depending on the PR construction.
- As I note in the previous post "boominess" is hard to relate to simulations. Nevertheless I dislike ported setups where the response begins to roll off but then bumps back up or even just shelves. I feel that is an indication that the related time domain response will have some degree of flaw.
- From work I did with automotive enclosures, I do not like your post #40. Instinct says that has a likelihood of acting like a number of tuned resonant tubes more than a simple air cavity. What was the reason for all those kind of tunnels? It can't be made with just like almost dowels sticking up from the surface to open up the inside volume more?
I like the "40 Hz Challenge!" idea. Maybe you'd have an easier time to start with the driver-find small drivers that can generate the necessary minimum SPL and then see what the boxes look like. The Purifi woofer goes low in a relative small box with a lot of SPL, more than 4L though I think. Hey is 4L too big to build into a top hat? A wearable backpack? Maybe you should just use a bass shaker?