Hi All,
This is my first post on this forum. I hope this gets posted under the corrected forum (subwoofers) without troubling the moderators for moving it into correct forum
I have already searched for this driver in this forum but could not find anything related to Hifi / home theater related and hence this thread.
Requirement
1. My requirement is to build a diy sub for home use (movies / tv content and seldom music)
2. I have chosen Beyma 18PWB1000Fe as the driver for this project because of the below factors
a) Given my living room is 21 feet all four sides (square) and its not acoustically treated, I figured a larger driver would be the right fit. Also it has good T/S parameters for a commercial driver - with frequency below 30hz and xmax around 13 mm
b) Cost - while there are drivers specifically designed for diy home use (Sb acoustics, Dayton etc), their cost is way too high in India (am citing a 12 inch driver here).
3. I do not expect to listen at higher SPL / reference level (like 120 or 110). I just need to hear good sound rumbles at moderate volumes. If this is achievable I could even build another one.
Questions / Clarifications
1. Is Beyma 18PWB1000Fe a good choice for Home entertainment purposes? I own a marantz AVR which will be connected to a power amp (to be decided) as the source - The answer to this question will pretty much determine whether or not I should proceed further
2. Currently I have tuned the enclosure to 24hz (pls see pictures) with 400w signal. The cone excursion exceeds around 20 hz - will I run into problems here with moderate volume levels? Please also look at group delay and port velocity and suggest what can be improved.
3. Having said above, I have seen folks suggesting to tune way lower like 20hz and below. Can I tune lower too? but although I understand the disadvantage of tuning lower is we will lose so much SPL which requires lot of EQ to recover back, I do not how that could work. If I apply some Parametric filters, the cone excursion exceeds - Its relational theory I guess and in summary, you have to give up / compromise on either SPL / tuning frequency but would be good to know how to build a balanced system.
2. Are there any other subwoofers (commercial similar to Beyma) that you think I should rather consider for this?
My observations
After plugging in the T/S parameters in winisd, I figured I will 10 CF enclosure to tune around 25 hz. Since my living room can accommodate this size (corner), I will not have problems with the size.
If all the experts here could share their insights on this topic that would be really help me in making an informed decision.
I also take this opportunity to thank all the members for an incredible job in building this DIY community -
Thank you
This is my first post on this forum. I hope this gets posted under the corrected forum (subwoofers) without troubling the moderators for moving it into correct forum
I have already searched for this driver in this forum but could not find anything related to Hifi / home theater related and hence this thread.
Requirement
1. My requirement is to build a diy sub for home use (movies / tv content and seldom music)
2. I have chosen Beyma 18PWB1000Fe as the driver for this project because of the below factors
a) Given my living room is 21 feet all four sides (square) and its not acoustically treated, I figured a larger driver would be the right fit. Also it has good T/S parameters for a commercial driver - with frequency below 30hz and xmax around 13 mm
b) Cost - while there are drivers specifically designed for diy home use (Sb acoustics, Dayton etc), their cost is way too high in India (am citing a 12 inch driver here).
3. I do not expect to listen at higher SPL / reference level (like 120 or 110). I just need to hear good sound rumbles at moderate volumes. If this is achievable I could even build another one.
Questions / Clarifications
1. Is Beyma 18PWB1000Fe a good choice for Home entertainment purposes? I own a marantz AVR which will be connected to a power amp (to be decided) as the source - The answer to this question will pretty much determine whether or not I should proceed further
2. Currently I have tuned the enclosure to 24hz (pls see pictures) with 400w signal. The cone excursion exceeds around 20 hz - will I run into problems here with moderate volume levels? Please also look at group delay and port velocity and suggest what can be improved.
3. Having said above, I have seen folks suggesting to tune way lower like 20hz and below. Can I tune lower too? but although I understand the disadvantage of tuning lower is we will lose so much SPL which requires lot of EQ to recover back, I do not how that could work. If I apply some Parametric filters, the cone excursion exceeds - Its relational theory I guess and in summary, you have to give up / compromise on either SPL / tuning frequency but would be good to know how to build a balanced system.
2. Are there any other subwoofers (commercial similar to Beyma) that you think I should rather consider for this?
My observations
After plugging in the T/S parameters in winisd, I figured I will 10 CF enclosure to tune around 25 hz. Since my living room can accommodate this size (corner), I will not have problems with the size.
If all the experts here could share their insights on this topic that would be really help me in making an informed decision.
I also take this opportunity to thank all the members for an incredible job in building this DIY community -
Thank you
Attachments
It looks like a good choice for the application and circumstances, personally I would go for the lower tuning and not worry too much about SPL. I'd see more excursion at lower input as a plus and wouldn't really worry about excursion either.
You haven\t mentioned port air velocity, is that in check?
You haven\t mentioned port air velocity, is that in check?
Greets!
Hornresp
sims 10 ft^3 net/25 Hz Fb = > ~120 dB/m/20 Hz/lossy corner/400 W, 10" dia. x 25" L. vent to get an acceptable vent mach.
Good 'rule of thumb' [ROT] is to limit BR to ~ a half octave below Fs = 0.707*27 = ~19 Hz, though a whole octave [~13.5 Hz] works for corners IF it's a really massive/rigid construction where nearly all of the theoretical +9 dB of gain is available or protect the speaker with at least a 4th order hi-pass and preferably 8th order. That, or cut power limit to 0.25/octave.
Hornresp
sims 10 ft^3 net/25 Hz Fb = > ~120 dB/m/20 Hz/lossy corner/400 W, 10" dia. x 25" L. vent to get an acceptable vent mach.
Good 'rule of thumb' [ROT] is to limit BR to ~ a half octave below Fs = 0.707*27 = ~19 Hz, though a whole octave [~13.5 Hz] works for corners IF it's a really massive/rigid construction where nearly all of the theoretical +9 dB of gain is available or protect the speaker with at least a 4th order hi-pass and preferably 8th order. That, or cut power limit to 0.25/octave.
Thank you Rademakers for your response.
Yes I could go ahead and tune lower but I don't really know about the downsides of tuning an enclosure lower than driver's resonant frequency Fs (27hz). Does it harm the driver in anyway at moderate listening levels?
Sorry I forgot to attach the port velocity - please see the port velocity picture.
What I am also very much concerned is about the Group Delay and boominess. Is there a parametric range that decides where the boominess is expected? please see attached and how it can be tackled if not completely avoided in a system?
I have also simulated (pls review) the SB Acoustics 12 inch woofer (probably comes at similar cost to Beyma's 18 inch). SB Acoustics looks far more better in terms of linear response below 30hz at 2.5 cubic feet.
Given the room size (21 x 21 feet all 4 sides), I just dont know if single or even dual 12 inch would shine over Beyma's 18 inch.
Thanks
Attachments
Thank you GM for your response.
I have not simulated this in Hornresp but to be honest I am not familiar with the below terms either.
Could you please elaborate a bit on what is ROT and BR if you dont mind?
"Good 'rule of thumb' [ROT] is to limit BR to ~ a half octave below Fs = 0.707*27 = ~19 Hz"
And the response at 120db at 20hz I would think it is simulated at 1 meter distance?
Thank you
I have not simulated this in Hornresp but to be honest I am not familiar with the below terms either.
Could you please elaborate a bit on what is ROT and BR if you dont mind?
"Good 'rule of thumb' [ROT] is to limit BR to ~ a half octave below Fs = 0.707*27 = ~19 Hz"
And the response at 120db at 20hz I would think it is simulated at 1 meter distance?
Thank you
He means that you can make a reflex enclosure for this to a half octave below Fs (27Hz) so that should be 19Hz. The curve down will be slightly going down before, but in a room that is not bad as room gain will fill that up. ROT is "rule of thump" and BR is "bass reflex".
And i agree this is a relative good driver for a bass reflex for cinema. It will be big with a big long port to tune it that low, but it's certainly possible. And you won't need the full 1kW to have bass, but that is not bad neighter because a lot of heardroom mostly means a more pure sound. I would run it with a 1 to 1.5kW amp full open altough to keep that headroom also on the amp site (and arrange volume with the dsp or preamp).
Thank you waxx for interpreting very clearly.
I have attached the curves for 19hz tuned at 2 different enclosure levels.
With 400w as input,
1. 10 cubic feet - Blue line
2. 14 cubic feet - Orange line
The curve of 14 CF looks lot better, it is literally a massive bookshelf with 3 x 5 inch 28 inches length port.
I have attached the curves for 19hz tuned at 2 different enclosure levels.
With 400w as input,
1. 10 cubic feet - Blue line
2. 14 cubic feet - Orange line
The curve of 14 CF looks lot better, it is literally a massive bookshelf with 3 x 5 inch 28 inches length port.
Attachments
Can someone please explain how should the graph for Marty sub enclosure look like? Especially transfer magnitude function. My understanding is that the curve of the Marty sub needs to be flat until the tuning frequency or tuning frequency needs to be achieved at say -3db and it also requires a very large enclosure like 12 cub feet.
I wonder how other folks make mini Marty cube within 7 cubic feet and still say tuned to 18 or 16hz. Although the port may be long, the transfer function magnitude won't look like the one with 12 cubic feet. Doesn't the output at low frequency falls off here? Or Is it a matter of tuning low and comparing spl? Please clarify.
I wonder how other folks make mini Marty cube within 7 cubic feet and still say tuned to 18 or 16hz. Although the port may be long, the transfer function magnitude won't look like the one with 12 cubic feet. Doesn't the output at low frequency falls off here? Or Is it a matter of tuning low and comparing spl? Please clarify.
Flat to tuning frequency = T/S max flat alignment:
net volume [Vb] [L] = 20*Vas*Qts'^3.3
box tuning [Fb] [Hz] = 0.42*Fs*Qts'^-0.96
[Qts']: [Qts] + any added series resistance [Rs]: Calculate new Qts with Series Resistor
No 'free lunch', so less acoustic efficiency [less Vb]/same tuning = more rolled off at a higher corner frequency.
net volume [Vb] [L] = 20*Vas*Qts'^3.3
box tuning [Fb] [Hz] = 0.42*Fs*Qts'^-0.96
[Qts']: [Qts] + any added series resistance [Rs]: Calculate new Qts with Series Resistor
No 'free lunch', so less acoustic efficiency [less Vb]/same tuning = more rolled off at a higher corner frequency.
Also take into account the acoustics. Adding a sub is not an easy as people think. Room modes will have a large impact on your results. A good summary: Multiple Subwoofer after Geddes
Ok, so I have come back with two choices of tuning - 22hz & 27hz (27hz is also Fs)
22hz - blue
27hz - red
power - 600watts
1. I would like to understand which curve would provide in optimal in room response / room gain - please advise.
2. Do I have worry about the group delay curve? Will there be any boomy bass?
This is mostly for tv & movies content in 441 sq feet hall (21 feet all sides) with no obstacles other than a sofa. Placement for the sub will be corner as this will take big enclosure.
Please see attached graphs and advise,
Thanks in advance.
22hz - blue
27hz - red
power - 600watts
1. I would like to understand which curve would provide in optimal in room response / room gain - please advise.
2. Do I have worry about the group delay curve? Will there be any boomy bass?
This is mostly for tv & movies content in 441 sq feet hall (21 feet all sides) with no obstacles other than a sofa. Placement for the sub will be corner as this will take big enclosure.
Please see attached graphs and advise,
Thanks in advance.
Attachments
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