About time I did this as the drivers are still in the small [ 15l] sealed car boxes. I have almost finished the 2.5-Way using the Vifa P25 as the .5 woofer but SWMBO now wants to use these speakers in the lounge room.
My copy of J Bagbys program no longer works with my version on W7 and Excell
We simply don't have the room to use the TL box that was designed with members help ( takes up too much real estate ) and the Boss wants something similar in design to the other boxes.
I have a height of 400mm to play with if the sub is to fit below the speaker and not have the tweeter too high.
My initial thought is a slightly oversized sealed box of about 50 liters but ported may be a better choice.
Room is small and lossy; 4.2 * 4.2 with 2.7 ceilings and some minor room treatment on the rear wall, large window on the North and a arched opening into the dining room on the South with very heavy carpet on the floor.
Maximum depth available is 300mm; which is why I initially thought heavily damped and sealed
Factory spec for the driver are Fs 23/ Qms 4.31/ Qes .358 / Vas 79.8l / DCr 3.3 X Max +/-19mm [38 total] Driver displacement ~4liters SD ~ 560cm<2??
My copy of J Bagbys program no longer works with my version on W7 and Excell
We simply don't have the room to use the TL box that was designed with members help ( takes up too much real estate ) and the Boss wants something similar in design to the other boxes.
I have a height of 400mm to play with if the sub is to fit below the speaker and not have the tweeter too high.
My initial thought is a slightly oversized sealed box of about 50 liters but ported may be a better choice.
Room is small and lossy; 4.2 * 4.2 with 2.7 ceilings and some minor room treatment on the rear wall, large window on the North and a arched opening into the dining room on the South with very heavy carpet on the floor.
Maximum depth available is 300mm; which is why I initially thought heavily damped and sealed
Factory spec for the driver are Fs 23/ Qms 4.31/ Qes .358 / Vas 79.8l / DCr 3.3 X Max +/-19mm [38 total] Driver displacement ~4liters SD ~ 560cm<2??
Hmm, ‘volume displacement’ [Vd] historically referred to the driver’s swept volume, so Sd = [0.13 ft^3*1728]/0.75” = 299.52”^2/1932.383 cm^2, which of course isn’t right, ergo apparently C-V means its box displacement [Vid] when mounted on the baffle face.
What is the approximate diameter of the surround across its center? It won’t be 100% accurate, but close enough. That, or considering its big surround, use a Shiva’s or similar high excursion 12” = 481 cm^2.
Anyway, at a glance, ~1.98 ft^3 + 0.13 [driver] + 0.3 [vent/bracing] = 2.14 ft^3 net is about the smallest vented I’d use, so the cab will need to be wider than tall, deep. ‘Critically’ damp the cab, vent as required.
GM
What is the approximate diameter of the surround across its center? It won’t be 100% accurate, but close enough. That, or considering its big surround, use a Shiva’s or similar high excursion 12” = 481 cm^2.
Anyway, at a glance, ~1.98 ft^3 + 0.13 [driver] + 0.3 [vent/bracing] = 2.14 ft^3 net is about the smallest vented I’d use, so the cab will need to be wider than tall, deep. ‘Critically’ damp the cab, vent as required.
GM
255mm to the centre of the double surround So Sd is probably closer to 500 than 560
GM after all the work and help you gave me working out the best TL for these drivers it's a real shame we don't have the floor space.
I guess I was asking about relevant SQ between a [ relatively] small vented box and a [relatively] large sealed if both boxes were the same size.
Crossing over @ ~ 80 to clean up the midbass on the 10inch Vifa
GM after all the work and help you gave me working out the best TL for these drivers it's a real shame we don't have the floor space.
I guess I was asking about relevant SQ between a [ relatively] small vented box and a [relatively] large sealed if both boxes were the same size.
Crossing over @ ~ 80 to clean up the midbass on the 10inch Vifa
Sorry, I don't have handy access to a really good simulator. It looks like a sealed Q=0.7 is about 22 liters. So unless you can build a significantly larger box, ported won't work well, you'll have a peak.
It is not clear to me how much internal cabinet volume you can have. You mentioned 2 dimensions-external?-but not the 3rd. How big a cabinet can you make exactly?
It is not clear to me how much internal cabinet volume you can have. You mentioned 2 dimensions-external?-but not the 3rd. How big a cabinet can you make exactly?
None of my simulation programs are working ATM. not since I upgraded to W7
For many reasons related to WAF I am restricted in size
600 wide 485 high and 300 deep but the front must be truncated ~45 to match the tops so front baffle no wider than 375mm That's about 50 liters which is a .6 sealed box [ and maybe a bit closer to .56 with enough stuffing] I only have 200 watts available so a critically damped box is OK but a ported box may be a bit boomy and not deep enough as I don't know how far below Fs I can tune in such a small box
I can boost at 30 +/- 6dB if I get my preamp going [ parametric EQ]
For many reasons related to WAF I am restricted in size
600 wide 485 high and 300 deep but the front must be truncated ~45 to match the tops so front baffle no wider than 375mm That's about 50 liters which is a .6 sealed box [ and maybe a bit closer to .56 with enough stuffing] I only have 200 watts available so a critically damped box is OK but a ported box may be a bit boomy and not deep enough as I don't know how far below Fs I can tune in such a small box
I can boost at 30 +/- 6dB if I get my preamp going [ parametric EQ]
Double surround? Don’t have a clue how to measure these except dynamically, plus the one’s I’m familiar with are very non-linear to get the desired ER series guitar ‘tone’. I thought all the woofers had a big half round surround. Memory’s really getting dim though and for whatever reason, the info Google found didn’t help much.
I did? Got a link? It must have been quite awhile back as my only [ML]TL C-V project I can find is for a Vega 154. I lost [or at least can’t access] most of my speaker and other on-line stuff along with all my PM correspondence in a motherboard melt-down while doing a BU several years ago.
Anyway, [too] small vented Vs same size sealed favors the sealed with a best overall of both being a ~aperiodic alignment IME, so has historically been my choice and it can always be sealed up.
GM
GM we did the 124s at the same time as the 154 and I too have lost all my old stuff for a similar reason. I'll go sealed, it is much easier and probably cleaner
http://www.musicaearte.com/Progetti...8d4 -104 - 10d4 - 124 - 12d4 - 154 - 15d4.PDF
http://www.musicaearte.com/Progetti...8d4 -104 - 10d4 - 124 - 12d4 - 154 - 15d4.PDF
Hmmm...
You could go smaller-than-normal ported, and use some eq to get the low end up. IMO, sealed boxes always need some kind of eq anyway, so if you can fit the port in the box, the headroom gain may well be worth it.
I did a 75L box for a JBL GTO1214, tuned ~19Hz. Applied about 6dB of boost in the low end, worked a treat.
You could go smaller-than-normal ported, and use some eq to get the low end up. IMO, sealed boxes always need some kind of eq anyway, so if you can fit the port in the box, the headroom gain may well be worth it.
I did a 75L box for a JBL GTO1214, tuned ~19Hz. Applied about 6dB of boost in the low end, worked a treat.
Decided to go with a sealed box for speed of making reasons. it will be a little smaller than I wanted but that's due to WAF
First layer of the box is 12mm chipboard
The boss wants these painted black to blend in with all the other stuff against the black wall.
Outer skin will be MDF and thickness will depend on what I can find in the shed so I need to do something to stiffen and damp the cabinet
I can use scraps of chipboard or ply to stiffen but I'm wondering what using cement sheet or ceramic tiles on the inside would have; never having used these before
Box will be filled of course using fiberglass and a layer of polyester batt[ to stop the possibility of glass fibers getting into the voice coil
First layer of the box is 12mm chipboard
The boss wants these painted black to blend in with all the other stuff against the black wall.
Outer skin will be MDF and thickness will depend on what I can find in the shed so I need to do something to stiffen and damp the cabinet
I can use scraps of chipboard or ply to stiffen but I'm wondering what using cement sheet or ceramic tiles on the inside would have; never having used these before
Box will be filled of course using fiberglass and a layer of polyester batt[ to stop the possibility of glass fibers getting into the voice coil
Folks have claimed good performance from cement board and various type tiles. I've used those cheap adhesive backed vinyl floor tiles and for more serious damping, the thick rubber industrial ones attached with the flexible, non-hardening caulk used for sub-flooring.
As a general rule, these can add enough stiffness, damping to reduce/delete the need for bracing except for mass loading the driver to the cab if not too large.
GM
As a general rule, these can add enough stiffness, damping to reduce/delete the need for bracing except for mass loading the driver to the cab if not too large.
GM
Tiles I have but no tile adhesive LOL Cement sheet I can glue with PVA but I just found out my scraps are loaded with asbestos [ really old off-cuts] so I won't be using them I guess its a little bracing and some MDF as usual. In a way it doesn't matter as these are cheaper trial boxes anyway.
I just try and do things right if I can
We have an American visitor we are showing around later today so tomorrow I'll take some pix and post them
Not much to show tho. it's just a box
I just try and do things right if I can
We have an American visitor we are showing around later today so tomorrow I'll take some pix and post them
Not much to show tho. it's just a box
Stupid cat moment. SWMBO has a cat, a very curious cat, a very curious cat covered all down its back with quick setting high strength waterproof PVA adhesive, Luckily I didn't get scratched too badly when I grabbed her and washed the excess of with a wet towel
Damned thing jumped inside box #2 as I was clamping it up and her back got all the excess glue
Was worth a facebook post when the Boss got home
Damned thing jumped inside box #2 as I was clamping it up and her back got all the excess glue
Was worth a facebook post when the Boss got home
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