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Old 27th January 2013, 07:33 PM   #141
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as just a thought, you may get a better imaging by lowering the the mid-range horn. seems one should stand all the time to listen to music
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Old 27th January 2013, 08:17 PM   #142
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Moving on - Lots of listening going on at the same time...

I have a 29lt rear chamber on the bass horn - pretty much the smallest enclosure.
15" driver it seems typically has a volume of ~6lt. I'm a bit unclear is that is just the cone and not the basket = negligible, and the magnet = perhaps a lt?

So I have around 23lt there as is. I loaded in 5 lt, got me to 18lt.
That was close to the right vol for the conicals (17lt). All good.
Current Hornresp calc for the Hyper bass horns is 14lt if I use the design feature.

Hmm, some expanding foam (specialist stuff) in a bag is how I made a race seat once.
That could work. Bags of known vol and can be made to fit around the driver nicely and fill up the back square of the chamber too...
More thought needed.

Last edited by Speedysteve7; 27th January 2013 at 08:35 PM.
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Old 27th January 2013, 09:02 PM   #143
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Quote:
Originally Posted by Speedysteve7 View Post
15" driver it seems typically has a volume of ~6lt. I'm a bit unclear is that is just the cone and not the basket = negligible, and the magnet = perhaps a lt?

Hmm, some expanding foam (specialist stuff) in a bag is how I made a race seat once.
That could work. Bags of known vol and can be made to fit around the driver nicely and fill up the back square of the chamber too...
6 liter seems like a bit more volume than cone, basket and magnet structure for a 15".
I ran out of elbow macaroni trying to figure out the displacement of an 18"...

Bagged expanding foam would work to reduce volume, use the more dense type. "Great Stuff" brand available at Home Depot seems to hold up well, but it really is messy, wear gloves unless you don't mind blotchy hands for a week or two.
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Old 28th January 2013, 07:19 AM   #144
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Yup - See previous posts... i've probably become used to it so a drop down will be interesting, I am ~5m away from the horns too.

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as just a thought, you may get a better imaging by lowering the the mid-range horn. seems one should stand all the time to listen to music
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Old 28th January 2013, 07:23 AM   #145
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6lt does seem a lot for cone but the mag is pretty big. I have not found any manufacture data so far.

Yeah an easy big filler is to cover the driver in there with polythene and then expanding foam around. With the can type as you say messy and sticks like the proverbial - you also can't do sealed bags as it needs air to set. The two pack race seat stuff sets in a sealed space. I don't really need that as I can fill in and let it foam up inside contained by polythene and then trim it to shape / reduce bit by bit.

First I need to figure out how / what to measure as maravedis said.

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Originally Posted by weltersys View Post
6 liter seems like a bit more volume than cone, basket and magnet structure for a 15".
I ran out of elbow macaroni trying to figure out the displacement of an 18"...

Bagged expanding foam would work to reduce volume, use the more dense type. "Great Stuff" brand available at Home Depot seems to hold up well, but it really is messy, wear gloves unless you don't mind blotchy hands for a week or two.

Last edited by Speedysteve7; 28th January 2013 at 07:49 AM.
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Old 28th January 2013, 12:47 PM   #146
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Quote:
Originally Posted by Speedysteve7 View Post
NP David.

Well, 2nd one knocked up:

Much less edge smoothing needed with the angle cuts.

Click the image to open in full size.

Not finished fully but quite smooth in there for the 100 - 350Hz waveys.
Quite an effort to get done in a weekend.

Listening now - Drottningholm Baroque ensemble among others. Great church organ use on bass and DEEP bass (Tapped H handles that pf course).
Bass vocals are nice too.
Quite different to the big conicals. More detail is audible. I can turn these up more and get a nice character to tenor and bass vocals.
I'd say they integrate better with the mid horns - others have said the same thing about round Hyper or Exponential profile bass horns. How much diff round vs square actually makes I do not know - prob not much, but I like the round look.

I have back box tuning to do by measuring (more guidance needed by maravedis on that one) - should take care of an evening or two
Then I can drop the other drivers and re-time align and see how that sounds - never ends, just as it should be
Beautiful work!!!
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Old 28th January 2013, 12:49 PM   #147
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Quote:
Originally Posted by Speedysteve7 View Post
Moving on - Lots of listening going on at the same time...

I have a 29lt rear chamber on the bass horn - pretty much the smallest enclosure.
15" driver it seems typically has a volume of ~6lt. I'm a bit unclear is that is just the cone and not the basket = negligible, and the magnet = perhaps a lt?

So I have around 23lt there as is. I loaded in 5 lt, got me to 18lt.
That was close to the right vol for the conicals (17lt). All good.
Current Hornresp calc for the Hyper bass horns is 14lt if I use the design feature.

Hmm, some expanding foam (specialist stuff) in a bag is how I made a race seat once.
That could work. Bags of known vol and can be made to fit around the driver nicely and fill up the back square of the chamber too...
More thought needed.
If I am reading you right, you can submerge the bags of material in a pale of water and read the displacement. That will give you the volume of the material.

P.S., are you smoothing those on a lathe of some sort???
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Old 28th January 2013, 02:42 PM   #148
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I built a rotating platform which helps spin the piece slowly as I use a drum sander to shape and check against profile. That is what worked best for me.

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Originally Posted by djn View Post
If I am reading you right, you can submerge the bags of material in a pale of water and read the displacement. That will give you the volume of the material.

P.S., are you smoothing those on a lathe of some sort???
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Old 28th January 2013, 10:38 PM   #149
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Bass horn chamber vols

More playing with hornresp back chamber vols and thinking what I have...

I have a total rear chamber of 30 or near 31 litres. If the driver takes up what 4/5 or 6 ltr then I have a vol of about 25 or 26 lts say.

Hornresp says that i should have 14lt... It also says that 25lt on Pi 1.0 works ok'ish. Now I do not run so close to the back wall as to get that 1.0. Changing to Pi 2.0 and I get a big step down in the region of 150Hz to 90Hz or perhaps a hump around 150 is another way to describe it...
This is pretty much what I've measured.
Dropping the chamber vol to 14lts in Hornresp cures that. Nice and flat.

So I've got to get around 11 or 12 lts of vol in there - One way to do that is to use foam and polythene. Fill it all up making a removable insert. Put that in a bag with all the air sucked out and Archimedes Eureka it. Volume known. I can cut it into pieces for various volumes to try and measure...

I'll let you know how I get on. I can see the wife giving me some interesting looks on this one
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Old 28th January 2013, 10:53 PM   #150
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Quote:
Originally Posted by Speedysteve7 View Post
Bass horn chamber vols


So I've got to get around 11 or 12 lts of vol in there - One way to do that is to use foam and polythene. Fill it all up making a removable insert. Put that in a bag with all the air sucked out and Archimedes Eureka it. Volume known. I can cut it into pieces for various volumes to try and measure...

I'll let you know how I get on. I can see the wife giving me some interesting looks on this one
Small baggies of sand work well for that
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