I seem to remember that some time ago Speaker Builder ran a series of designs where the driver was mounted in a box which was ported into a larger rear enclosure where the size wasn't too critical - cupboard, car boot (trunk), etc.
Maybe this concept could be tuned with a variovent type of arrangement (or a sock in the tube - I've still got some spare socks that I haven't yet filled with sand).
Steve
Maybe this concept could be tuned with a variovent type of arrangement (or a sock in the tube - I've still got some spare socks that I haven't yet filled with sand).
Steve
problematic driver
Hi everione, i have read all posts and exchanges mails with some speakers gurus like troels gravesen, and the variovent appears t be the only solution for some "decent bass". the driver parameters are these:
Z: 8 Ohms
Re : 5,5 Ohms
Fr: 46 Hz
Qa: 4,2
Qe: 0,7
Qt: 0,6
Mms: 0,034371 Kg
Cms: 3,48E-04 New/m
Bl: 8,84 Wb/m
Sd: 0,035968 m2
Vas: 6,31E-02 m3
Rms: 2,37 Kg/s
the simulation programs like WinISD and BassBoxPro 6 says an ideal enclosure about 100 L or more. a 45-50 liter cb is mandatory.
Someone can help with the folowing?
How many variovents?
size of each?
how much material inside each one?
material compressed or loose?
placing in enclosure?
thanks, gaston
Hi everione, i have read all posts and exchanges mails with some speakers gurus like troels gravesen, and the variovent appears t be the only solution for some "decent bass". the driver parameters are these:
Z: 8 Ohms
Re : 5,5 Ohms
Fr: 46 Hz
Qa: 4,2
Qe: 0,7
Qt: 0,6
Mms: 0,034371 Kg
Cms: 3,48E-04 New/m
Bl: 8,84 Wb/m
Sd: 0,035968 m2
Vas: 6,31E-02 m3
Rms: 2,37 Kg/s
the simulation programs like WinISD and BassBoxPro 6 says an ideal enclosure about 100 L or more. a 45-50 liter cb is mandatory.
Someone can help with the folowing?
How many variovents?
size of each?
how much material inside each one?
material compressed or loose?
placing in enclosure?
thanks, gaston
For my records, what brand/model driver is this and are these published or measured specs? Pe, Le, Xmax?
Don't know what the Variovent's DF is, but doing a sim in MJK's PORTED WS to determine a DIY golden ratio 1.75ft^3 (gross) cab variant:
L = 23.4"
W/D = 8.93" x 14.16"
driver down 10.82"
stuffing density = 0.2lbs/ft^3, or ~5.6oz of polyfil
vent = 2" dia x 4" long stuffed with ~5.6oz of polyfil (contain on each side with a mesh screen)
vent down 22"
No real bass output to speak of though with an aneochoic ~60Hz F3, this cab is just too small.
GM
Don't know what the Variovent's DF is, but doing a sim in MJK's PORTED WS to determine a DIY golden ratio 1.75ft^3 (gross) cab variant:
L = 23.4"
W/D = 8.93" x 14.16"
driver down 10.82"
stuffing density = 0.2lbs/ft^3, or ~5.6oz of polyfil
vent = 2" dia x 4" long stuffed with ~5.6oz of polyfil (contain on each side with a mesh screen)
vent down 22"
No real bass output to speak of though with an aneochoic ~60Hz F3, this cab is just too small.
GM
The driver is an Audifiel 10bx, made in Argentina. I'm studying there. Is the best affordable driver I can get. The audio world here is so so prehistoric, that drivers like scan-speak, vifa, morel and so on does not exist!. the bestyou can get are car drivers from pioneer, some alpine and they are really expensive for a student, so the 10bx is the only choice. See it at www.audifiel.com
The specs are not published, since the driver does not have then on it's box. So i wrote to the manufacturers and they sent them las week. The other parameters says "1" in the exel file they sent, that's why i did not post them. So Troels suggested the variovents as the only solution to get nice bass from the 10bx, and that's why i'm here.
Thanks again, i will try a 42 L cab with a home made variovent on the back, tuned by ear. Some suggestions and advices will be WELL received.
gaston
The specs are not published, since the driver does not have then on it's box. So i wrote to the manufacturers and they sent them las week. The other parameters says "1" in the exel file they sent, that's why i did not post them. So Troels suggested the variovents as the only solution to get nice bass from the 10bx, and that's why i'm here.
Thanks again, i will try a 42 L cab with a home made variovent on the back, tuned by ear. Some suggestions and advices will be WELL received.
gaston
Hang on.
The Thiele-Small specs the company sent said the resonant frequency was 46 Hz. At least, that is what is posted on the forum.
But the company's website lists "Frecuencia de resonancia: 35 Hz".
Just guessing, but that sounds more in line with what most companies put out.
If the free air resonant frequency is indeed 35 Hz instead of 46 Hz, that is almost half an octave lower and will yield a speaker with far better performance than what we are talking about so far.
The Thiele-Small specs the company sent said the resonant frequency was 46 Hz. At least, that is what is posted on the forum.
But the company's website lists "Frecuencia de resonancia: 35 Hz".
Just guessing, but that sounds more in line with what most companies put out.
If the free air resonant frequency is indeed 35 Hz instead of 46 Hz, that is almost half an octave lower and will yield a speaker with far better performance than what we are talking about so far.
Re: problematic driver
Bad news and good news.
The bad news is that these Thiele Small parameters all affect each other according to a certain formula. I don't use the formula, I just plug the Thiele-Small numbers into Bullock and White's freeware, (DOS BoxModel), and let the program compute it. Essentially, all the other Thiele-Small parameters confirm that the resonance is indeed 46 Hz.
Now, two good pieces of good news.
A) The same formula and program calculate your 1 meter/1 watt sensitivity as 91.4 db. That is somewhat higher than normal, and so your slightly high F3 frequency is counterbalanced by that.
B) Your speaker, when placed into a 50 liter box, has a final Qtc of 0.9. Is that good news? Yes. Because an acceptable Qtc for sealed box woofer is between 0.5 and 1.0, and your woofer is within that range.
If you stuff your box with lots of stuffing, you're F3 will go down somewhat, but so will your sensitivity, (efficiency). But then, you are already more efficient than most speakers, so you have some to spare.
You can put a variovent on the box, and it will probably lower the Qtc down to 0.7 or so. Again, 0.7 is within the acceptable range, but so is 0.9, which is what you have without the variovent.
All this boils down to is that assuming the company is giving you accurate Thiele-Small specs, you can put your speaker into a 50 liter cabinet with
A) Either a large or a small amount of stuffing,
B) Put a variovent or NOT put a variovent in the cabinet,
and you still have a pretty good speaker, well within the accepted range, whatever you do.
The F3 will be a little higher than normal, but the efficiency is also a little higher. So it balances out.
Go build your 50 liter cabinet with peace of mind.
gaston_pdu said:
Bad news and good news.
The bad news is that these Thiele Small parameters all affect each other according to a certain formula. I don't use the formula, I just plug the Thiele-Small numbers into Bullock and White's freeware, (DOS BoxModel), and let the program compute it. Essentially, all the other Thiele-Small parameters confirm that the resonance is indeed 46 Hz.
Now, two good pieces of good news.
A) The same formula and program calculate your 1 meter/1 watt sensitivity as 91.4 db. That is somewhat higher than normal, and so your slightly high F3 frequency is counterbalanced by that.
B) Your speaker, when placed into a 50 liter box, has a final Qtc of 0.9. Is that good news? Yes. Because an acceptable Qtc for sealed box woofer is between 0.5 and 1.0, and your woofer is within that range.
If you stuff your box with lots of stuffing, you're F3 will go down somewhat, but so will your sensitivity, (efficiency). But then, you are already more efficient than most speakers, so you have some to spare.
You can put a variovent on the box, and it will probably lower the Qtc down to 0.7 or so. Again, 0.7 is within the acceptable range, but so is 0.9, which is what you have without the variovent.
All this boils down to is that assuming the company is giving you accurate Thiele-Small specs, you can put your speaker into a 50 liter cabinet with
A) Either a large or a small amount of stuffing,
B) Put a variovent or NOT put a variovent in the cabinet,
and you still have a pretty good speaker, well within the accepted range, whatever you do.
The F3 will be a little higher than normal, but the efficiency is also a little higher. So it balances out.
Go build your 50 liter cabinet with peace of mind.
gaston_pdu said:
With no variovent, and a 42 liter cab, your F3 will be 61 Hz instead of 59 Hz with a 50 liter cab, and a Qtc=0.95 instead of a Qtc=0.9 with a 50 liter cab. Pretty close. Again, any Qtc between 0.5 and 1.0 is acceptable. But you can still put a variovent in it anyway, as it will almost certainly produce a Qtc within the acceptable range.
Yes, I was suggesting a 6HX for the mids and highs. No tweeter for the high end.You could use the money that you would spend on the tweeter and its crossover and use it to buy this higher quality driver.
It might sound really good in a dipole open baffle and the graph shows that it has very good highs. This would be the same idea as some designs with Lowthers or Fostex drivers which also incorporate the small "whizzer cone"
If later you find that the highs are missing, you could add a super tweeter covering just the highest frequencies.
It might sound really good in a dipole open baffle and the graph shows that it has very good highs. This would be the same idea as some designs with Lowthers or Fostex drivers which also incorporate the small "whizzer cone"
If later you find that the highs are missing, you could add a super tweeter covering just the highest frequencies.
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