Hi all
I'm (in the process of) making a subwoofer using two of these 8" drivers.
I decided to set up a new thread here because of the actual specs of these drivers... and the price (£16)
T/S parameters are...
Fs - 33Hz
Qts - 0.3528
Qes - 0.3964
Qms - 3.21
Vas - 56.8L
Sd - 0.0216
Re - 11.6
Vd - 64.93cm^3
Xmax - 3mm
Le - 0.59mH
8 ohm/coil
60W rms/coil
100W rms peak, with no damage
88.94 dB/W/m
I put these into winISD before buying the driver, got some very nice results...
Link to buy some is...
http://cpc.farnell.com/LS00415/audio-video-tv/product.us0?sku=unbranded-55-1455
See what you think
Will post more on the sub I'm making later on...
I'm (in the process of) making a subwoofer using two of these 8" drivers.
I decided to set up a new thread here because of the actual specs of these drivers... and the price (£16)
T/S parameters are...
Fs - 33Hz
Qts - 0.3528
Qes - 0.3964
Qms - 3.21
Vas - 56.8L
Sd - 0.0216
Re - 11.6
Vd - 64.93cm^3
Xmax - 3mm
Le - 0.59mH
8 ohm/coil
60W rms/coil
100W rms peak, with no damage
88.94 dB/W/m
I put these into winISD before buying the driver, got some very nice results...
Link to buy some is...
http://cpc.farnell.com/LS00415/audio-video-tv/product.us0?sku=unbranded-55-1455
See what you think
Will post more on the sub I'm making later on...
I thot the part number looked familiar... this is probably the same woofer but local to the USA
http://mcmelectronics.com/product/55-1455
dave
http://mcmelectronics.com/product/55-1455
dave
Yeah - they're the same ones...
I really like them... there's decent low-end frequency response, and the higher end rolls off nicely
I'm planning on using 2 of them is a 42L cube, sealed with Linkwitz, to go to -3dB @28Hz
It says 3mm Xmax, but even after that there is only a little distortion.
I dare say there are better drivers out there, but not for that price.
I really like them... there's decent low-end frequency response, and the higher end rolls off nicely
I'm planning on using 2 of them is a 42L cube, sealed with Linkwitz, to go to -3dB @28Hz
It says 3mm Xmax, but even after that there is only a little distortion.
I dare say there are better drivers out there, but not for that price.
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If it's of interest, I also used two 8's in a sealed box of about this volume. The results were pretty good - but ultimately SPL will be limited by the volume of air those drivers can move, being 'only' 8" and with limited x-max.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=140069
http://www.diyaudio.com/forums/showthread.php?s=&threadid=140069
14.11dB
loses 1db per Hz down after that.
Sounds good in some bigger boxes - had to put bottles of water in to reduce int. volume to 21L/driver.
pics of the spreadsheet attatched.
red line = correction
Green = overall output
Blue = pre-corrected output.
For the driver size, and the simplicity, and the price, the speed and low-end bass guitar bits are damn good.
loses 1db per Hz down after that.
Sounds good in some bigger boxes - had to put bottles of water in to reduce int. volume to 21L/driver.
pics of the spreadsheet attatched.
red line = correction
Green = overall output
Blue = pre-corrected output.
For the driver size, and the simplicity, and the price, the speed and low-end bass guitar bits are damn good.
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Interesting to note here - you can achieve v.high mid-bass SPLs using relatively small drivers...
Use harmonics (2nd, 3rd, to around 11th) and your brain fills in the fundamental.
I am fiddling with this concept to get huge SPLs without much Xmax being used...
Not what I'm after, though... may use it as an add-on later.
Use harmonics (2nd, 3rd, to around 11th) and your brain fills in the fundamental.
I am fiddling with this concept to get huge SPLs without much Xmax being used...
Not what I'm after, though... may use it as an add-on later.
Hi,
do you realise that you are sending 25.7times the power to the pair of 8s compared to a flat signal sent to the remainder of the system. That's what +14.1dB of LF gain does.
Your total bass power handling is 120W.
Divide by 25.7 and that gives the maximum equivalent power you will send to the satellites. I would not be happy with a maximum power of 4.7W into my satellites. That's only +6.7dB of overhead above an average level of 1W. I look for at least +20dB of overhead to reduce the number of transients that get clipped.
My advice, investigate what can be achieved with +10dB of LF gain.
do you realise that you are sending 25.7times the power to the pair of 8s compared to a flat signal sent to the remainder of the system. That's what +14.1dB of LF gain does.
Your total bass power handling is 120W.
Divide by 25.7 and that gives the maximum equivalent power you will send to the satellites. I would not be happy with a maximum power of 4.7W into my satellites. That's only +6.7dB of overhead above an average level of 1W. I look for at least +20dB of overhead to reduce the number of transients that get clipped.
My advice, investigate what can be achieved with +10dB of LF gain.
You forget - DVC woofers.
240w rms power handling.
The REALLY low bass on a CD is also typically around 10dB down, meaning there is only 4dBs more power required.
the idea of this project is to go low, not loud, but thanks for the concern.
240w rms power handling.
The REALLY low bass on a CD is also typically around 10dB down, meaning there is only 4dBs more power required.
the idea of this project is to go low, not loud, but thanks for the concern.
No, you forget. The quoted power handling already takes into account both coils. Also it's a max rating, in reality probably 50-60 RMS.
What you are proposing is about 99% identical to my first major sub-woofer project, a good many years ago now. Build it, but don't think you will get any serious SPL from it. Your theory about the harmonics giving you extra apparent SPL is wrong, it just sounds like a cheap sub being thrashed.
What you are proposing is about 99% identical to my first major sub-woofer project, a good many years ago now. Build it, but don't think you will get any serious SPL from it. Your theory about the harmonics giving you extra apparent SPL is wrong, it just sounds like a cheap sub being thrashed.
E-mailed them about that.
60W rms per coil
100W peak.
And, like I said - loudness doesn't matter, just how low it goes.
60W rms per coil
100W peak.
And, like I said - loudness doesn't matter, just how low it goes.
I hope to do the same - I'm only 15 years old, so this sub was designed to go low, not loud, as SWMBO just cuts my room out on the fusebox if the music "accidentally" gets too loud.
This isn't for a living room HT system - it's for a room 3mx3.5m
Thanks for the encouragement etc.
PS To double check - http://mcmelectronics.com/product/55-1455 says the same - 60W rms per coil.
PPS - As I am 15, my budget is also quite small (compared to most people here) - £100, so I got some cheap drivers, and decided to make something reasonable out of them.
This isn't for a living room HT system - it's for a room 3mx3.5m
Thanks for the encouragement etc.
PS To double check - http://mcmelectronics.com/product/55-1455 says the same - 60W rms per coil.
PPS - As I am 15, my budget is also quite small (compared to most people here) - £100, so I got some cheap drivers, and decided to make something reasonable out of them.
For a small room and with a mum to please I'm sure it will work out quite well. I cut my teeth on using cheap parts, it's the best way as occasionally things go wrong or get abused 🙂
According to Dad (who's usually with me when the music gets too loud, cheering me on), this sub is only a small, test version of the full thing.
I think he's thinking 12" or more for the final piece.
This could get interesting, but I think it will happen much later on...
And I know what you mean by abused.
I sometimes have a few friends over after school (parents work full-time, so they get home at 5, and i get home at 3-15). And there's always one who yells "crank it up", so, I turn it up a bit, then there's the usual yell of "louder", until the whole thing is distorting like crazy, and the electricity meter is spinning.
Those kind of volumes only last until someone smells an amp cooking.
Which doesn't matter, because I got the amp from school, for free, and they have 4 more "broken" ones.
I think he's thinking 12" or more for the final piece.
This could get interesting, but I think it will happen much later on...
And I know what you mean by abused.
I sometimes have a few friends over after school (parents work full-time, so they get home at 5, and i get home at 3-15). And there's always one who yells "crank it up", so, I turn it up a bit, then there's the usual yell of "louder", until the whole thing is distorting like crazy, and the electricity meter is spinning.
Those kind of volumes only last until someone smells an amp cooking.
Which doesn't matter, because I got the amp from school, for free, and they have 4 more "broken" ones.
One of the things I learnt from the project was to really choose drive units more carefully and do more analysis and modelling before purchase. Also how to correlate what I saw on the models to how it worked in real life.
If you are stuck for boards for the project I have all the designs you will ever need on my website.
If you are stuck for boards for the project I have all the designs you will ever need on my website.
Yeah - this is my 2nd project.
The first went horribly wrong when I decided to go down the PA speaker route.
SWMBO wasn't pleased
Neither was I, as I wanted to do a 178L box, ended up with a 28L box
The first would have gone flat to 40Hz, and really loud, the 2nd was rubbish.
Nevermind, eh?
Only cost me £30 to have a good mess around.
But this time, I drew up all the graphs, different type of cabinets, decided on sealed + Linkwitz, as it was one of the smallest designs.
The first went horribly wrong when I decided to go down the PA speaker route.
SWMBO wasn't pleased
Neither was I, as I wanted to do a 178L box, ended up with a 28L box
The first would have gone flat to 40Hz, and really loud, the 2nd was rubbish.
Nevermind, eh?
Only cost me £30 to have a good mess around.
But this time, I drew up all the graphs, different type of cabinets, decided on sealed + Linkwitz, as it was one of the smallest designs.
Sounds like we have trod similar paths 🙂 I saw the Linkwitz Transform as the answer to all the problems, but only with time and experience can you understand the pitfalls and trade-offs and the true requirements for the driver and power behind it. Have fun.
Hi chris661,all,
A last minute suggestion:
Why not build a stuffed T-TQWT (Tapped-( folded) Tapered Quarter Wave Tube) using the two suggested drivers.
Only one internal divider and two bracings is needed.
See the submitted picture 1(1) of a HR simulation.
Folding technique and the placing of the port, example:
My sons T-TQWT (BP-TQWT) is described here:
http://www.diyaudio.com/forums/showthread.php?postid=1653128#post1653128
And pictures at:
http://www.diyaudio.com/forums/showthread.php?postid=1658457#post1658457
http://www.diyaudio.com/forums/showthread.php?postid=1757771#post1757771
b
1(1)
A last minute suggestion:
Why not build a stuffed T-TQWT (Tapped-( folded) Tapered Quarter Wave Tube) using the two suggested drivers.
Only one internal divider and two bracings is needed.
See the submitted picture 1(1) of a HR simulation.
Folding technique and the placing of the port, example:
My sons T-TQWT (BP-TQWT) is described here:
http://www.diyaudio.com/forums/showthread.php?postid=1653128#post1653128
And pictures at:
http://www.diyaudio.com/forums/showthread.php?postid=1658457#post1658457
http://www.diyaudio.com/forums/showthread.php?postid=1757771#post1757771
b
1(1)
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