Best to ignore power ratings, there are no standards and they are essentially meaningless. A garbage spec.
dave
ok so a redesign to accommodate the larger speakers i received.
i had to increase the internal volume *and* widen the ports to keep velocity down.
end result is it looks a bit tubby now. its actually only 2 litres more internal volume, but it looks much bigger.
quite annoying!
anyway, attached are an spl graph at equal power input (green is 8 inch, red line is 10 inch, blue line is 10 inch in old 8 inch enclosure.) a port velocity graph, and a quick screengrab.
both graphs are shown without lowpass filters. obviously with lowpass the 10 can go much louder than the 8, but not in the old cabinet, vent velocity gets very high
i had to increase the internal volume *and* widen the ports to keep velocity down.
end result is it looks a bit tubby now. its actually only 2 litres more internal volume, but it looks much bigger.
quite annoying!
anyway, attached are an spl graph at equal power input (green is 8 inch, red line is 10 inch, blue line is 10 inch in old 8 inch enclosure.) a port velocity graph, and a quick screengrab.
both graphs are shown without lowpass filters. obviously with lowpass the 10 can go much louder than the 8, but not in the old cabinet, vent velocity gets very high
Attachments
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The name "swiss roll" is getting less and less suitable. It was always a bit fraudulent though since you're not actually from Switzerland.
Maybe you could paint it yellow with pink and white checkers on the top and call it the Battenburg Cake? I mean sure it sounds a bit German but it was invented in the UK at least.
On a more serious note about the design, I still think it looks good (did you test the new size with the original cylinder?) You could also consider giving it a less precise geometric shape to see how that looks.
These Void Acoustic subs show the sort of elegance that can be achieved. You're certainly not restricted by the acoustic properties of the enclosure, and the more it looks like a piece of art or furniture the less it'll seem in the way.
You might want to try modelling it with stuff on it. It just seems like such an obvious little table to me. I reckon the ultra-minimalist style will definitely be set off by putting things on it like ornaments or books or candles or something.
Maybe you could paint it yellow with pink and white checkers on the top and call it the Battenburg Cake? I mean sure it sounds a bit German but it was invented in the UK at least.
On a more serious note about the design, I still think it looks good (did you test the new size with the original cylinder?) You could also consider giving it a less precise geometric shape to see how that looks.
These Void Acoustic subs show the sort of elegance that can be achieved. You're certainly not restricted by the acoustic properties of the enclosure, and the more it looks like a piece of art or furniture the less it'll seem in the way.
You might want to try modelling it with stuff on it. It just seems like such an obvious little table to me. I reckon the ultra-minimalist style will definitely be set off by putting things on it like ornaments or books or candles or something.
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Dayton audio RSS265HO-4 10 inch High Output Subwoofer | Loudspeaker freaks
Thats the driver. Im testing my designs in borh versions of winisd and also hornresp.. Still cant get my head round the change in lf falloff with that transmission line setting.
Thats the driver. Im testing my designs in borh versions of winisd and also hornresp.. Still cant get my head round the change in lf falloff with that transmission line setting.
Europe audio/Loudspeaker freaks
@ robinlawrie
Thanx for the PDF link
You were lucky dealing with them, as others have had issues
http://www.diyaudio.com/forums/multi-way/187520-bmm-electronics-europe-audio-7.html
Maybe they sent the 10's as the 8'2 were out of stock ?
Simming the RSS265HO*4 i discovered something unusual between WiniSD & HornResponse - http://www.diyaudio.com/forums/subwoofers/311268-discrepancy-winisd-hornresponse.html#post5160783
@ robinlawrie
Thanx for the PDF link
You were lucky dealing with them, as others have had issues
http://www.diyaudio.com/forums/multi-way/187520-bmm-electronics-europe-audio-7.html
Maybe they sent the 10's as the 8'2 were out of stock ?
Simming the RSS265HO*4 i discovered something unusual between WiniSD & HornResponse - http://www.diyaudio.com/forums/subwoofers/311268-discrepancy-winisd-hornresponse.html#post5160783
Cool project - thanks for posting it.
That's a bummer about the 10" woofers being sent instead of 8. Seemed very familiar to me. Last time I ordered 8" woofers from Parts Express they sent 10s. What? Why did they do that? Checked my order. Yeah... I had ordered 10s.
Hope you can return them or use them, but it doesn't make your slick looking sub as compact.
That's a bummer about the 10" woofers being sent instead of 8. Seemed very familiar to me. Last time I ordered 8" woofers from Parts Express they sent 10s. What? Why did they do that? Checked my order. Yeah... I had ordered 10s.
Hope you can return them or use them, but it doesn't make your slick looking sub as compact.
id imagine enough cake would be quite effective room treatment.
im definitely keeping the 10's. from my simulations the difference even in the same cabinet as the 8's is minimal. bit more spl, couple of hz higher f3/6/10
ive spoken to my cnc guy, who says its no problem swapping over to 22mm plywood, which will make the thing a bit taller, and gain a couple of litres in volume.
-unfortunately if i increase the width, it goes from a 2 sheet job to a two and a little bit sheet job.. and that wood aint cheap.
so im probably going to compromise somewhat on ideal cabinet dimensions.. but like i said, differences in performance are not large, and the 10 inch driver has a ton of headroom (double the power handling, larger area, more xmax) , so i can eq them a bit to make up any deficit.
the vent velocity gets a touch high (30m/s at xmax) , bit as i understand from david/planet10's comments, the actual vent velocity in such a restrictive vent will be lower than the simulations suggest. also, i am literally never gonna run these things flat out..
im definitely keeping the 10's. from my simulations the difference even in the same cabinet as the 8's is minimal. bit more spl, couple of hz higher f3/6/10
ive spoken to my cnc guy, who says its no problem swapping over to 22mm plywood, which will make the thing a bit taller, and gain a couple of litres in volume.
-unfortunately if i increase the width, it goes from a 2 sheet job to a two and a little bit sheet job.. and that wood aint cheap.
so im probably going to compromise somewhat on ideal cabinet dimensions.. but like i said, differences in performance are not large, and the 10 inch driver has a ton of headroom (double the power handling, larger area, more xmax) , so i can eq them a bit to make up any deficit.
the vent velocity gets a touch high (30m/s at xmax) , bit as i understand from david/planet10's comments, the actual vent velocity in such a restrictive vent will be lower than the simulations suggest. also, i am literally never gonna run these things flat out..
About the transmission line thing, you might want to have a look at this.
Discrepancy between WinISD & HornResponse
The error may be with WinISD
Discrepancy between WinISD & HornResponse
The error may be with WinISD
ok so i have just had the drivers ive purchased described as "mud shovels" over on the class-d forum..
they are poor at low volumes, lack precision, and cannot be used over 80 hz or so due to poor impulse response apparently.
are they really so bad?
if so, why -o why didnt anyone warn me before i purchased ( i was planning on the 8's admittedly, but i assume they share the same properties as the 10's)
ive only ever heard good things about these drivers, but admittedly, most of the reviews are by car audio users (not all though i must add)
they are poor at low volumes, lack precision, and cannot be used over 80 hz or so due to poor impulse response apparently.
are they really so bad?
if so, why -o why didnt anyone warn me before i purchased ( i was planning on the 8's admittedly, but i assume they share the same properties as the 10's)
ive only ever heard good things about these drivers, but admittedly, most of the reviews are by car audio users (not all though i must add)
it has been pointed out to me, that the sub i have will exceed the maximum potential of the dual alpair 7 cabinets ive chosen with only circa 150w of input.
my simulations approximately correlate with this.. at xmax the mains ( 2 alpairs in a box) will hit about 105db
with 150w input, one of my subs will do about the same..
this obviously leaves a lot on the table with my sub drivers.
ive been playing around tuning them lower, then eq'ing them up to get more extension with the headroom i have.
with a 20 litre cabinet, and port tuned to 20 hz instead of the circa 28-30 i was considering before, i can keep within xmax with a 10db boost at 20 hz, while matching the spl of alpairs.
this drops my f3 point to 20 hz or so.
id note ive been told that
a) spl/power etc are not relevant
b) f3 is meaningless
c) a nice gentle slope off in bass response is desireable.
id also note that
a) music generally doesnt contain 20hz content, but movies sometimes do
however, with heavy duty subs, and relatively small high ends.
is it a reasonable idea to tune the subs lower, to eq and take advantage of the extra excursion and power handling available?
attached are 2 screengrabs
one is the alpairs (dual) and the sub, tuned to 20 hz, with alpairs at xmax, and subs adjusted to similar level.
-note ive put a lowpass on the sub at 120 hz, and a higpass on the alpairs at 100 hz.
the other is the same setup with a 10 db boost at 20 hz. just within xmax
- id say the slope of the non-eq'ed sub looks quite good if i get big room gain.
-eq'ed one shows eq headroom possible within xmax if i have gaps in response.
one thing i also note.. amplifier apparent load in eq'ed scenario peaks at 765 VA
im not sure quite how this would relate to the amplifier rating in watts i would need to achieve such eq..
my simulations approximately correlate with this.. at xmax the mains ( 2 alpairs in a box) will hit about 105db
with 150w input, one of my subs will do about the same..
this obviously leaves a lot on the table with my sub drivers.
ive been playing around tuning them lower, then eq'ing them up to get more extension with the headroom i have.
with a 20 litre cabinet, and port tuned to 20 hz instead of the circa 28-30 i was considering before, i can keep within xmax with a 10db boost at 20 hz, while matching the spl of alpairs.
this drops my f3 point to 20 hz or so.
id note ive been told that
a) spl/power etc are not relevant
b) f3 is meaningless
c) a nice gentle slope off in bass response is desireable.
id also note that
a) music generally doesnt contain 20hz content, but movies sometimes do
however, with heavy duty subs, and relatively small high ends.
is it a reasonable idea to tune the subs lower, to eq and take advantage of the extra excursion and power handling available?
attached are 2 screengrabs
one is the alpairs (dual) and the sub, tuned to 20 hz, with alpairs at xmax, and subs adjusted to similar level.
-note ive put a lowpass on the sub at 120 hz, and a higpass on the alpairs at 100 hz.
the other is the same setup with a 10 db boost at 20 hz. just within xmax
- id say the slope of the non-eq'ed sub looks quite good if i get big room gain.
-eq'ed one shows eq headroom possible within xmax if i have gaps in response.
one thing i also note.. amplifier apparent load in eq'ed scenario peaks at 765 VA
im not sure quite how this would relate to the amplifier rating in watts i would need to achieve such eq..
Attachments
Can you expand on this? I'm trying to make a sub that fits under a couch and I was thinking of using 1" legs. How does the floor loading affect the woofer's parameters? Is it like extra added mass? If yes, do you know how to approximate it before actually building the box?
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