I own a pair of Cerwin Vega D9 with a 15" woofer. I've never been that happy with the mids-highs or the way they are positioned so out everything goes everything... but my woofers.
I am rebuilding a new box with high end dayton and vifa drivers. But since these will sit separate and on top of the woofer box, I need to cut a bit on the height of the woofer box. So I need to cut about 20% on the volume.
The specs on that woofer (152WR) are nowhere to be found so I will have to guess. The stock box has two 10" long X 4" round ports, and the new one will have one 16 3/4" by 2" rectangular port at the bottom. What I can play with is the port length. I do not mind paying with efficiency, these will be bi-amped.
I have ordered a Dayton test microphone, and was thinking of looking at frequency responses with different port lengths.
I am looking for suggestions and ideas on the "how". (Please, not on the "if" or "why").
I am rebuilding a new box with high end dayton and vifa drivers. But since these will sit separate and on top of the woofer box, I need to cut a bit on the height of the woofer box. So I need to cut about 20% on the volume.
The specs on that woofer (152WR) are nowhere to be found so I will have to guess. The stock box has two 10" long X 4" round ports, and the new one will have one 16 3/4" by 2" rectangular port at the bottom. What I can play with is the port length. I do not mind paying with efficiency, these will be bi-amped.
I have ordered a Dayton test microphone, and was thinking of looking at frequency responses with different port lengths.
I am looking for suggestions and ideas on the "how". (Please, not on the "if" or "why").
Is your Dayton microphone a USB version?
Have you considered turning the box upside down? If you make it smaller you can always use it as a closed box and equalise it. Otherwise you might want to measure some Thiele/Small parameters to use to simulate the vented box.
Have you considered turning the box upside down? If you make it smaller you can always use it as a closed box and equalise it. Otherwise you might want to measure some Thiele/Small parameters to use to simulate the vented box.
Yes, the microphone is a UMM-6 usb, that I am planning to use with RoomEQ Wizard.
I have considered flipping the box, but the top drivers would sit too high to my taste, even removing the 2" base.
Measuring the stock box parameters before doing anything is a great idea I wish I came up with - thanks
I have considered flipping the box, but the top drivers would sit too high to my taste, even removing the 2" base.
Measuring the stock box parameters before doing anything is a great idea I wish I came up with - thanks
Ok. Putting it on it's side is an option even though it may look untidy.
No problem. It's just not a good choice for crossover work.
Have you considered simply flipping the box onto its side?
Also not being familiar with the speaker are these the closed back midranges?
If they are the cheap closed back would it be easier to use the original box and replace the drivers with better units and redo the XO?
Also not being familiar with the speaker are these the closed back midranges?
If they are the cheap closed back would it be easier to use the original box and replace the drivers with better units and redo the XO?
I have not considered filpping the box on its side, but I do not have the room.
The stock mid ranges are closed back and horrible. And the plastic tweeters, arghhh... I am replacing them with a pair of tang band W5-704D, and the tweeters are Vifa/Peerless BC25SG15-04
The original box is a major issue, the mid-highs being on a 18" wide surface, killing dispersion. That is why I am adding a separate thinner enclosure for them.
And that enclosure will hold 2 of each driver, angled 30 degrees off-center.
Not easy to visualize, I should be able to post a photo of the box in the next couple of days.
The stock mid ranges are closed back and horrible. And the plastic tweeters, arghhh... I am replacing them with a pair of tang band W5-704D, and the tweeters are Vifa/Peerless BC25SG15-04
The original box is a major issue, the mid-highs being on a 18" wide surface, killing dispersion. That is why I am adding a separate thinner enclosure for them.
And that enclosure will hold 2 of each driver, angled 30 degrees off-center.
Not easy to visualize, I should be able to post a photo of the box in the next couple of days.
Just using outside online dimensions.
Then working out a realistic internal volume
judging by cabinet wall thickness
Factory cabinet seems to be 5.2 to 5 cubic feet or 142 to 147 Liters
with the 2 factory ports Fb
or reflex point be around 30 to 32 Hz
I dont know the internal volume
of your new box.
but would likely keep tuning about the same or lower
28 to 32 Hz
16.75" x 2" port
has a cross sectional area of 216 cm^2
I can only guess this is a typical slot port
that shares 3 walls.
So end correction will be high
K=2.227 for 3 shared walls.
WinIsd only has up to K=.850
so the calculated length is much much too long.
Once we know the volume of new enclosure
can calculate what length is needed to get you
in 28 to 30 Hz tuning.
far as volume the driver probably do ok
in 4 to 5 cubic feet.
my buddy had vegas similar to D9
the sealed mids are tolerable. but my god
yes the tweeter was very crunchy and horrible
bass was very nice and they looked cool for sure
Then working out a realistic internal volume
judging by cabinet wall thickness
Factory cabinet seems to be 5.2 to 5 cubic feet or 142 to 147 Liters
with the 2 factory ports Fb
or reflex point be around 30 to 32 Hz
I dont know the internal volume
of your new box.
but would likely keep tuning about the same or lower
28 to 32 Hz
16.75" x 2" port
has a cross sectional area of 216 cm^2
I can only guess this is a typical slot port
that shares 3 walls.
So end correction will be high
K=2.227 for 3 shared walls.
WinIsd only has up to K=.850
so the calculated length is much much too long.
Once we know the volume of new enclosure
can calculate what length is needed to get you
in 28 to 30 Hz tuning.
far as volume the driver probably do ok
in 4 to 5 cubic feet.
my buddy had vegas similar to D9
the sealed mids are tolerable. but my god
yes the tweeter was very crunchy and horrible
bass was very nice and they looked cool for sure
WhiteDragon, thank you for taking the time.
I am looking at 4.35 cubic feet, including the full-width slot port at the bottom (woofer is on top) which you guessed correctly.
The port width is fixed at 16" 3/4, but the 2" was just a wild guess on my part for where to start.
I will make it smaller based on your recommendation, and have RoomEQ fine tune it.
Oh and I am not sure what we call "3 shared walls", the port will open in the back at the bottom, be the full width of the box, with one wall separating it from the woofer volume.
I am looking at 4.35 cubic feet, including the full-width slot port at the bottom (woofer is on top) which you guessed correctly.
The port width is fixed at 16" 3/4, but the 2" was just a wild guess on my part for where to start.
I will make it smaller based on your recommendation, and have RoomEQ fine tune it.
Oh and I am not sure what we call "3 shared walls", the port will open in the back at the bottom, be the full width of the box, with one wall separating it from the woofer volume.
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Kinda can of worms but not really.
4.35 cubic feet will be reduced a bit.
Once you add the driver, the port etc etc
since they displace volume.
All in All let us assume
once the port and speaker are in there.
118 to 123 liters or about 4.35 to 4.1 cubic feet
sticking with 16.75" x 2 " port exit
Or 216 cm^2 cross sectional area.
rounded off numbers and average of
what gross / net volume might be
4 to 4.35 cubic feet
32 Hz 5.25" to 5.75" length
30 Hz 8.25" to 8.75" length
28 Hz 11.75" to 13" length
opinions vary, I would keep tuning low as possible
those lengths are based on the slot port sharing 3
walls. or K=2.227
so like most slot ports lengths are shorter
Since the walls make the port appear longer/ less efficiency
4.35 cubic feet will be reduced a bit.
Once you add the driver, the port etc etc
since they displace volume.
All in All let us assume
once the port and speaker are in there.
118 to 123 liters or about 4.35 to 4.1 cubic feet
sticking with 16.75" x 2 " port exit
Or 216 cm^2 cross sectional area.
rounded off numbers and average of
what gross / net volume might be
4 to 4.35 cubic feet
32 Hz 5.25" to 5.75" length
30 Hz 8.25" to 8.75" length
28 Hz 11.75" to 13" length
opinions vary, I would keep tuning low as possible
those lengths are based on the slot port sharing 3
walls. or K=2.227
so like most slot ports lengths are shorter
Since the walls make the port appear longer/ less efficiency
@WhiteDragon
Would you mind assisting me with a slot port estimation?
For my really big box project.
Would you mind assisting me with a slot port estimation?
For my really big box project.
It's the box in this thread
https://www.diyaudio.com/community/threads/new-party-project-best-use-for-this-driver.390759/
Could you comment there rather than disrupt this one?
https://www.diyaudio.com/community/threads/new-party-project-best-use-for-this-driver.390759/
Could you comment there rather than disrupt this one?
This makes real solid ground to start playing - thanks.
Not worried about power though, they are so efficient and will have their own amp.
WhiteDragon, do you think 1.5" high port would be a better starting point to reach a lower Fb?
Not worried about power though, they are so efficient and will have their own amp.
WhiteDragon, do you think 1.5" high port would be a better starting point to reach a lower Fb?
As you are Bi-Amping have you considered doing a sealed box and using DSP?
Thinking purely about space issues, a sealed box might be a bit smaller
Thinking purely about space issues, a sealed box might be a bit smaller