1. No. I've told you 3 times now to do your sim with a high pass filter. When you do that you will lose at least a couple of db. My sim beats yours EVERYWHERE. At the low knee where yours has a peak mine will still be the same spl (maybe louder by a bit). Above the low knee where you don't have a peak my design smokes yours. My design is shown with a high pass filter. Redo your sim with a high pass filter in place and you will see that mine beats it even at the peak in the low knee in your sim.
2. Yes. But I fixed the velocity problem through design. My port was about 18 liters so you could shave about that much off the enclosure size and the box would then be just 30 liters.
yes that's for sure. I was talking about my usual sealed enclosures...
Obviously, the max SPL is the absolute max... the're is no EQ boost possible.
A little follow-up:
Did some very interesting test today. Before cutting the hole of my 50 liters enclosure for the passive radiator, i made a test in a sealed configuration. Wasn't expecting much from that 8 inch subwoofer in a sealed... I sure wasnt ready for such a surprise.
So, SPL calibrated mic, 1.3m distance from the driver and the enclosure 0.7m from the wall and about 3.5m from the corners + high ceiling. Pretty much like a 1,0-1,5 pi...
Pure tone 30hz.
Small ICEpower amplifier.
Single driver, exactly like that:
113db at 30hz in-room is not bad. Pretty impressive in fact. But what is even more impressive is the electrical energy required to achieve that:
31 watts.
Room mode helped, of course, but still. I tried different positions, including the mic, and it was always LOUD and efficient above 30hz.
That driver is exceptional. Was hard to believe i was listening to a 8 incher. Effortless, even 20hz pure tone.
Can't wait for the next test:
1. Passive radiator (waiting for the delivery)
2. More amp power (700AS2 is almost ready)
As far as i'm concerned, that's the most promising '' 28-35hz in a small enclosure '' solution that is under the radar at this moment.
Did some very interesting test today. Before cutting the hole of my 50 liters enclosure for the passive radiator, i made a test in a sealed configuration. Wasn't expecting much from that 8 inch subwoofer in a sealed... I sure wasnt ready for such a surprise.
So, SPL calibrated mic, 1.3m distance from the driver and the enclosure 0.7m from the wall and about 3.5m from the corners + high ceiling. Pretty much like a 1,0-1,5 pi...
Pure tone 30hz.
Small ICEpower amplifier.
Single driver, exactly like that:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
113db at 30hz in-room is not bad. Pretty impressive in fact. But what is even more impressive is the electrical energy required to achieve that:
31 watts.
Room mode helped, of course, but still. I tried different positions, including the mic, and it was always LOUD and efficient above 30hz.
That driver is exceptional. Was hard to believe i was listening to a 8 incher. Effortless, even 20hz pure tone.
Can't wait for the next test:
1. Passive radiator (waiting for the delivery)
2. More amp power (700AS2 is almost ready)
As far as i'm concerned, that's the most promising '' 28-35hz in a small enclosure '' solution that is under the radar at this moment.
Jon,
Nice driver, impressive 30 Hz response!
The Audio Control RTA gave me a flashback to the late 1980s, used to have one of those, great display visibility..
Did you happen to measure the driver's excursion during that "31 watt" test?
Did you measure the amp output voltage (31 watts into 3 ohms should be about 10 volts) ?
The dB reading is the sum of multiple bands, did you look at the harmonic (60Hz, 90 Hz, 120Hz, etc) levels vs. fundamental on the RTA display?
Art
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No, didnt have the chance to measure the excursion yet. I would say: it can take more
I'm using a calibrated wattmeter, can't remember the voltage but i'll check it next time. Everything is shown, amp, wattage, voltage, etc...
Did today a 118db but at the peak of another room mode: 51hz, with a bigger 250asx2 amp. This time it was more energy consuming: 238w (this time that was on the AC not the speaker cables)
Also did a 115.4db @ 30hz
Next monday, i'll try on a 700as2 and also in another (smaller) room.
I'm using a calibrated wattmeter, can't remember the voltage but i'll check it next time. Everything is shown, amp, wattage, voltage, etc...
Did today a 118db but at the peak of another room mode: 51hz, with a bigger 250asx2 amp. This time it was more energy consuming: 238w (this time that was on the AC not the speaker cables)
An externally hosted image should be here but it was not working when we last tested it.
Also did a 115.4db @ 30hz
Next monday, i'll try on a 700as2 and also in another (smaller) room.
Completely different (smaller) room today. About 40m³ or 15.4 ft. x 11' x 8'.
Same amp, same driver, same enclosure, same pure tones.
121db @ 54hz (244w)
and about 115db @ 38hz
(room modes changed, obviously)
But also more stable and better extension all the way to 20hz. Less SPL but flatter bass response. That includes the target 28-35hz...
Same amp, same driver, same enclosure, same pure tones.
An externally hosted image should be here but it was not working when we last tested it.
121db @ 54hz (244w)
and about 115db @ 38hz
(room modes changed, obviously)
But also more stable and better extension all the way to 20hz. Less SPL but flatter bass response. That includes the target 28-35hz...
Here is the full view of the Extech power analyzer:
That is on a ICEpower 700AS2 (left channel load only) @ 3 ohms
513 watts
56 volts
9.88 amp
An externally hosted image should be here but it was not working when we last tested it.
That is on a ICEpower 700AS2 (left channel load only) @ 3 ohms
513 watts
56 volts
9.88 amp
An externally hosted image should be here but it was not working when we last tested it.
and that is the result: 124db @ 51hz. The maximum i got in the (bigger) room mode.
The 8W7 can handle the wattage, at least short term, but on a pure tone that's the maximum i can get i think.
And finally, the maximum SPL i'm able to get @ 30hz, within my target bandwith, 118.6db. That is beyond the comfort zone, though, i just tortured it. As you can see on the picture, i'm most probably beyond xmax and close to xmech. The little beast just don't want to die.
I'm not power-amplifier-limited this time, so i guess the realistic SPL i'd get @ 30hz in this very room mode would be around 116db. Can't wait to see the difference between that sealed enclosure and with the passive radiator.
I'm not power-amplifier-limited this time, so i guess the realistic SPL i'd get @ 30hz in this very room mode would be around 116db. Can't wait to see the difference between that sealed enclosure and with the passive radiator.
An externally hosted image should be here but it was not working when we last tested it.
I just need to mention how absolutely bizarre it is that you are specifically playing only tones that land on room modes and then measuring the max spl based on that as if room modes were a benefit instead of a real problem. You're going about this like a car spl competition and it looks like that's the kind of sub you want, something that will hit big numbers but sound terrible.
When I show a sim (which I do somewhat often) if I describe the max spl I will refer to the lowest spl point in the passband. When I show a measurement (which I haven't done much for a few years now) I will try to take the measurement outside to AVOID room modes.
If you are sitting on a 20+ db room mode (which is easily possible) your measurements don't seem very impressive at all.
The fact that you measured in a room means your measurements are completely without reference and mean absolutely nothing to anyone except maybe you, and even then only if you use the sub in the room and in the exact position that you measured it in. Even then there's no reference at all to what the rest of the passband is doing so this seems like a fairly elaborate exercise that will ultimately give you no useful information at all.
This seems to be simply confirmation bias. You liked that driver before you started, you were presented with an option that would whup it's butt so you need to confirm to yourself that your chosen driver is the one. But in an unscientific manner and with no controls or references or even a comparison sub.
Good luck, you'll need it if you think this type of data is useful.
When I show a sim (which I do somewhat often) if I describe the max spl I will refer to the lowest spl point in the passband. When I show a measurement (which I haven't done much for a few years now) I will try to take the measurement outside to AVOID room modes.
If you are sitting on a 20+ db room mode (which is easily possible) your measurements don't seem very impressive at all.
The fact that you measured in a room means your measurements are completely without reference and mean absolutely nothing to anyone except maybe you, and even then only if you use the sub in the room and in the exact position that you measured it in. Even then there's no reference at all to what the rest of the passband is doing so this seems like a fairly elaborate exercise that will ultimately give you no useful information at all.
This seems to be simply confirmation bias. You liked that driver before you started, you were presented with an option that would whup it's butt so you need to confirm to yourself that your chosen driver is the one. But in an unscientific manner and with no controls or references or even a comparison sub.
Good luck, you'll need it if you think this type of data is useful.
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On the contrary, i'm getting very useful information.
Like: i'm better off using such high xmax/high power driver -in a limited volume cabinet- if i want to achieve max output somewhere around 30hz. Anything in that region is purely pistonic.
Also, the classic BR won't cut it, because of the port volume requirement at these low frequencies/power.
So ''last'' option and probably the better one, is the passive radiator.
Like: i'm better off using such high xmax/high power driver -in a limited volume cabinet- if i want to achieve max output somewhere around 30hz. Anything in that region is purely pistonic.
Also, the classic BR won't cut it, because of the port volume requirement at these low frequencies/power.
So ''last'' option and probably the better one, is the passive radiator.
Unless I'm reading you wrong you only seem to be reporting max spl at frequencies that fall on room modes.
If you want to make any reasonable conclusions about realistic sub locations you need to have the mic in the potential listening position. And you need to measure the frequency response, not just one or two frequencies. So I doubt you were attempting to find good locations for the sub in this spl measuring exercise.
I'm not sure how you came up with ANY of those conclusions.
You haven't tried anything but one driver in one cab, how do you know that's best and that it will give max spl at 30 hz? I would argue that big pro drivers in big resonant boxes would be MUCH better and give WAY more output at 30 hz.
That's a problem created by the driver itself, it's t/s want a relatively small box and that increases port length for a given tuning. I'm sure I could make a port work fine though.
That's hardly the last option. Most times when a port gets too long and unruly it's put into a reverse taper tl about the size a ported box would be. And if you use flare(s) things can become a lot easier.
Yeah, yeah., A JL audio W7 sound terrible...
Have you even heard one in a home audio/theater context ? Please tell us about it.
I've never heard that driver in any situation but if designed into any average SPL competition system I can guarantee it would sound terrible. Those systems are specifically designed to have an extremely irregular frequency response. That's what I was talking about, not the driver. Although I'm sure the driver doesn't sound very good when pushed to the excursion level shown in your picture.
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It's not designed for SPL competition. I think you're confusing with other brands such as RE, Sundown, CV, Orion and so on...
W7 series is a premium quality driver that happens to be able of very high output. Also used in their 25k studio/home theater subwoofers.
Some reading:
Car Audio - Subwoofer Drivers - W7AE
and Google is your best friend for the reviews, user comments etc..
It will never be as small as a PR. Especially tuned low with high output in mind.
Now, it might be questionnable wether the added few Db's in the 25-28hz region worth the (?? liters) extra volume, BR v.s. PR. Maybe it is, maybe not.
I'm not doing a new post here for anything i tried, tested or measured. So, yeah, i get the confusion here...
But, yes, i did try about half a dozen combo enclosure-drivers so far, in that very room (the large one, not the small). And once i'll get a rough idea of where it's all going, i'll make a proper comparison test. But for now, i'm still in exploration mode, nothing more. Anyway, so far the 49 liters sealed + 8W7 SMOKED the other enclosures/drivers i tested in the 30hz region... There is no comparision to be made, there is no serious contender! That will change very soon.
The thing is: that 8W7 is pretty much THE best solution among all 8'' nominal size driver. 216mm outer diameter is quite small and that is useful in my case. I'm sure not aware of any other driver this size that is capable of almost 500cm³ Vd... That seems underrated btw.
I still consider larger drivers but, usually, that comes with large volume cabinet requirements -especially in the targeted 28-35hz- and that's just not possible.
If you refer to post #1, it says that i'm looking for a ''Limited enclosure volume (relatively)'' and by relatively, it meant i didnt know what would be the threshold of diminishing return. Now, i think we can narrow it down to 40-70 liters total cabinet size. Which makes the Tapped horn solution almost impossible, unless you're using a 6'' driver. So what's left is the BR and PR.
Seems like anything smaller than 40 liters will suffer from lack of extension (the 28hz side) OR lack of output. Beyond 70 liters, i'd get more of everything, obviously, but all things considered MAYBE not so much that it could be day & night PER EXTRA LITER.
To make it clearer, with these hypothetical scenarios:
(max low-distortion in-room output)
#1. 105db @ 28hz in 20 liters enclosure
#2. 115db @ 28hz in 40 liters enclosure
#3. 120db @ 28hz in 80 liters enclosure
#4. 125db @ 28hz in 160 liters enclosure
#5. 128db @ 28hz in 320 liters enclosure
...I'd probably go for something between 2 and 3 because the extra Db-per-liter is not worth it (for me) passed a certain point. Not to mention that passed a certain point, absolute max SPL tends to be useless in normal music/movies listening everyday situations... I mean: 115db is a nice-to-have compared to 105db, at those low frequencies, but 125db V.S. 115db ? Not so sure. Not so sure i'd use that potential that often... But 115db ? Yes.
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FYI, the THSpud from Danley is a great reference point here:
https://www.danleysoundlabs.com/danley/wp-content/uploads/2012/04/TH-Spud-spec-sheet11.pdf
That's roughly 130 liters PER 8'' (they use 8 inches high excursion as well)
and we're talking 126db max SPL somewhere in the 19hz-125hz, more like 120-122db in the 28-35hz, which is great. But that's TWO drivers in a very big cabinet.
https://www.danleysoundlabs.com/danley/wp-content/uploads/2012/04/TH-Spud-spec-sheet11.pdf
That's roughly 130 liters PER 8'' (they use 8 inches high excursion as well)
and we're talking 126db max SPL somewhere in the 19hz-125hz, more like 120-122db in the 28-35hz, which is great. But that's TWO drivers in a very big cabinet.
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