I have a reasonable understanding of what this "room gain" is, all I'm saying is that if you account for room gain, you should also account for "room loss" at other frequencies, and then it's easier to just ignore "room gain" alltogether because it's just a complication. Also, lower notes need different walls of materials and thickness than high frequencies to see it as a true boundary.
Of course ! RIgidity and "soundproofness" should be put into the equation
Which equation ?
Myself, for making rattle all the house, just need a pair of 6 1/2 " @ 30 W
Either, a 8 " sub with a fleawatt amp ( TEA 2025 bridged)
Nowadays, a pair of 5" with 7" passive radiator is well enough to "shake my rump"
Of course the results will vary in the low end of things, but that is true whether the design is taking room response into account or not. At least in my view it is more elegant to work with the room than against it. What you usually get when room gain is not taken into account is a bass response that might be up to 15dB above your midrange. Boomy, that is. And then you'll get an equalizer or to be more modern a DSP to counter that.
Straight to 40Hz @ 100dB/W might be doable if you use the room to your benefit. But such a freefield response with your budget is very unlikely to be possible to be on the optimistic side on the debate.
Enough of this, wasted time chatting idly.
The kids are asleep and my wife is running about doing stuff, finally got a few minutes of simulation time in, first 7 hornresp minutes for months. Does not look half bad. Exact same box for both drivers. The 15LB075-UW4 can probably go a tiny bit lower almost flat, 15-600LF will probably have a smooth roll off if I aim lower. This looks almost like the golden size though.
Did not find Le of the 15LB075-UW4 so just entered 2, not sure what to put there. Also, spec says 900 cm2, I wrote 856 cm2 like in the 15-600LF spec sheet. Mmd is calculated.
Edit:
It is my general assumption that the 15-600LF is more realistic, and will behave better, but the 15LB075-UW4 is just too cheap to ignore. Simulates that xmax will be reached at 20v (100w/4ohm) with 117.3566db/50hz which is not a problem for me. The Fane reaches xmax at about 41v (ca 210W/8ohm) with 121.3991db/50hz
The kids are asleep and my wife is running about doing stuff, finally got a few minutes of simulation time in, first 7 hornresp minutes for months. Does not look half bad. Exact same box for both drivers. The 15LB075-UW4 can probably go a tiny bit lower almost flat, 15-600LF will probably have a smooth roll off if I aim lower. This looks almost like the golden size though.
Did not find Le of the 15LB075-UW4 so just entered 2, not sure what to put there. Also, spec says 900 cm2, I wrote 856 cm2 like in the 15-600LF spec sheet. Mmd is calculated.
Edit:
It is my general assumption that the 15-600LF is more realistic, and will behave better, but the 15LB075-UW4 is just too cheap to ignore. Simulates that xmax will be reached at 20v (100w/4ohm) with 117.3566db/50hz which is not a problem for me. The Fane reaches xmax at about 41v (ca 210W/8ohm) with 121.3991db/50hz
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Thank you doctormord.
Looks very similar, only smoother
The reason I simulate the drivers in the same box without further optimization is to have a more direct comparison. Also, I am having some concerns regarding possible side effects a larger enclosure might have on this driver.
Looks very similar, only smoother
The reason I simulate the drivers in the same box without further optimization is to have a more direct comparison. Also, I am having some concerns regarding possible side effects a larger enclosure might have on this driver.
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Sorry about the bumping here, non intentional.
Minor tweaks only, also tried varying the values some to check for possible issues, looks solid. Possible to build finished box at ca 95cm*43cm*54cm outer dimensions provided 15mm OSB is used, minimal bracing is accounted for (some 1,5cm*2cm strips along the middle of panels, possibly diagonal with break in middle, 2 crosses from wooden broom handles 1 above/1 below driver, needs tight fit). Should be ok to 300hz?
Need to have a plan for mid and up...
Minor tweaks only, also tried varying the values some to check for possible issues, looks solid. Possible to build finished box at ca 95cm*43cm*54cm outer dimensions provided 15mm OSB is used, minimal bracing is accounted for (some 1,5cm*2cm strips along the middle of panels, possibly diagonal with break in middle, 2 crosses from wooden broom handles 1 above/1 below driver, needs tight fit). Should be ok to 300hz?
Need to have a plan for mid and up...
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You have to add the Rg, which consists of the amplifier internal resistance and the crossover parts because that affects the Qt and therefore the behaviour in the bass (may be neglected if the driver is only used above the fb, i.e. midrange or tweeter). A common value is 0,2-0,3 for an active setup (depending on the amp, you can calculate it via the dampening factor) or the internal resistance + the serial coil(s) resistance. That would be typical 0,5-0,8 for a normal amp and a 6 or 12dB passive crossover, depending on which parts (coil) you use, for 18dB etc. you have to add all serial resistances. With steeper xo orders that quickly adds up.
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Icg
I cannot read your post properly because I think there are some metal shavings in my eyes, doctors closed and theres no way Im driving to the closest night open doctor with hardly any eyesight. Trying to look somewhere else when typing, bored and have to wait until opening hours to scrape off those steel shavings. Hurts to look directly on my phone...
Anyway, something about output impedance? Was thinking about using some LM4780 kits I have laying about. Not sure but think there's an output resistor.at 0.15ohm. So maybe 0.2is about right? Was thinking active xo.
Edit:
Really annoying about those steel shavings because I used #$@$@%&$&*""#:%!&((?$!;;$;%!?$?()$)?$!#;!#+%?$?( safety gear and &#:%;;"+#+#(-#--#+#((@)#(($+$-$-- really really annoying!
Edit2:
Nothing else to do and closing my eyes for any prolonged time is simply not happening. Took forever to find that %#%#&&@-@-+%++%+ mouse pointer, Nd then I missed it again and again..... Could not see much of a difference on the reponse except a tiny amount lower output as expected still very good, I expect the hornresp simulation might be off as much as 1.5db based on my intestine container (gut feeling), but maybe just 1db. Compared to simulations already posted
I cannot read your post properly because I think there are some metal shavings in my eyes, doctors closed and theres no way Im driving to the closest night open doctor with hardly any eyesight. Trying to look somewhere else when typing, bored and have to wait until opening hours to scrape off those steel shavings. Hurts to look directly on my phone...
Anyway, something about output impedance? Was thinking about using some LM4780 kits I have laying about. Not sure but think there's an output resistor.at 0.15ohm. So maybe 0.2is about right? Was thinking active xo.
Edit:
Really annoying about those steel shavings because I used #$@$@%&$&*""#:%!&((?$!;;$;%!?$?()$)?$!#;!#+%?$?( safety gear and &#:%;;"+#+#(-#--#+#((@)#(($+$-$-- really really annoying!
Edit2:
Nothing else to do and closing my eyes for any prolonged time is simply not happening. Took forever to find that %#%#&&@-@-+%++%+ mouse pointer, Nd then I missed it again and again..... Could not see much of a difference on the reponse except a tiny amount lower output as expected still very good, I expect the hornresp simulation might be off as much as 1.5db based on my intestine container (gut feeling), but maybe just 1db. Compared to simulations already posted
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Thank you for writing short, I could almost skim through the whole thing. I was editing my previous post, if you would be so kind as to re-read it that would be nice.
It's not so bad really, it's not like Uhmm.. Well, very very uncomfortable is what it is. Eyes want to close, but when you close your eyes it feels like getting sand in there, and when they move about you can feel the scrapings inside the eyelids, all I can see is a really blurry fog of light... Oh, and my nose is running for some reason unknown to me. Instinct tells you to close your eyes and blink it out but that only makes everything worse.
It's not so bad really, it's not like Uhmm.. Well, very very uncomfortable is what it is. Eyes want to close, but when you close your eyes it feels like getting sand in there, and when they move about you can feel the scrapings inside the eyelids, all I can see is a really blurry fog of light... Oh, and my nose is running for some reason unknown to me. Instinct tells you to close your eyes and blink it out but that only makes everything worse.
Well, if you cut off the whizzer, your radiation pattern will narrow down a lot below the horn and widen up further down (and up because of the horn and tweeter). I think that might not necessarily be the behaviour you'd like to have. That applies to all drivers of the same size because of the wavelength in relation to the membrane geometry/diameter. That means, if that's okay for you, then you could use a lot other non-fullrange-non-subwoofer 12" drivers just aswell.
A horn, 1 x 0,5 x 0,5 m, wooden-basic-material, is a roaring, rumbling thing (the calculation does not indicate, does not calculate this,-). Some strips would not amend. You could listen not loud. Or, if, than never! clean, never listen music. NO way,-!!! I had build some, little, big, very big ones. The way, to get a not rumbling casing in this size is to use stone, concrete, or any synthetics.
You are correct, but this is not news to me at least, I am merely having trouble finding good alternatives to choose from. As far as I can tell, the only solution available to get 100db/2.83v is with 4 x faital 3fe25 at such a low cost. 8" are too expensive and you'd also need 2, 6.5" does not give the required sensitivity and several of them to make up for it is also too pricey. There are 12" about, but they either cost too much, or must be bought from a place with higher shipping costs, not to mention the extra checkup bill at ca 30 euro for each package.
cumbb:
Then please explain to me, how to make a low budget concrete block that will not take any more space, nor weigh any more than if it was made from wood based materials. I am very confident that the problem you are pointing out will not be relevant with the correct placement of material, it may seem inadequate, but correct/optimal placement of small additions of material can under the right circumstances work just as well as larger quantities of material would. I am also considering filling the 2 unused voids in the box with polyurethane foam, as well as using felt layered flexible linoleum also stiffened with polyurethane foam to optimize the transition to the port area. It has worked quite well before. I know people say it has no discernible effect on low frequencies, but it most certainly does not do any harm either.
Edit:
Oh, and I just noticed some 18mm OSB at my local supplier, very positive surprise, I thought they only had 15mm.
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Well, the FAITAL PRO 3FE25 is really cheap, but 2 FAITAL PRO 8FE200 would outperform then at any time and at a higher impedance. There are also numerous other drivers which can do that. Every one of the options got advantages and disadvantages so you have to decide which criterias are the most important. I mean, a single 10" or 12" might also do a great job or maybe building a horn might be an option, it gives a huge spl boost.
Nevertheless, the bass is most likely still the weakest point, to get the spl there is the 'weakest point' after all.
My experiences:
Better to build some little casings than a big: it does shorten the resonances and reflections. And it is a mobile.-)
Brace by connecting the opposite planks by bars.
No mass, but rigid, stable: thin planks (max. 18 mm), more connections of the opposite, parallel planks: distance circa 10 cm! You would not need linoleum or bitumen than (damp not deeps, but wooden-mid-grey-grainy-flat-roaring: translate these "mids" into deeps - more balanced).
Volume within the (closed) casing is as loud as on the outside: to use the inside as mechanical amplificator is usual, is fine for looking-measurement, but not clean for listening-measurement. Do much more damp the inside. Do not use plasticwool. Better the foam. More better textile.
My experiences.
Better to build some little casings than a big: it does shorten the resonances and reflections. And it is a mobile.-)
Brace by connecting the opposite planks by bars.
No mass, but rigid, stable: thin planks (max. 18 mm), more connections of the opposite, parallel planks: distance circa 10 cm! You would not need linoleum or bitumen than (damp not deeps, but wooden-mid-grey-grainy-flat-roaring: translate these "mids" into deeps - more balanced).
Volume within the (closed) casing is as loud as on the outside: to use the inside as mechanical amplificator is usual, is fine for looking-measurement, but not clean for listening-measurement. Do much more damp the inside. Do not use plasticwool. Better the foam. More better textile.
My experiences.
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