No, haven't really done anything with DBRs beyond building one listed in one of Weems' books (which didn't impress me given its bulk) and a couple of sims. LspCad lets you highlight a field, then use the keyboard arrows to scroll in real time, so doing a sim is fast/easy.
Yeah, we're in the same time zone, so it's another ~sleepless night for me...........
Yeah, we're in the same time zone, so it's another ~sleepless night for me...........
DJN,
I cut out the pieces for another TH,this time 14" external width so will fit between studs or floor joists.
Seems to me having the opening at the end rather than the side would work fine,and allow the horn to be mounted vertically through the floor. If you have a cat or small dog,you will need a grill to avoid having to fish it from the bottom of the horn.Will need it to keep feet out, too...
Should have it completed in a day or two,will see how it compares with original,and will post changes in dimensions.
I cut out the pieces for another TH,this time 14" external width so will fit between studs or floor joists.
Seems to me having the opening at the end rather than the side would work fine,and allow the horn to be mounted vertically through the floor. If you have a cat or small dog,you will need a grill to avoid having to fish it from the bottom of the horn.Will need it to keep feet out, too...
Should have it completed in a day or two,will see how it compares with original,and will post changes in dimensions.
GM said:
I'll build a straight TH if someone can tell me which of these drivers (that I own) would work in a TH.
Adire shiva 12" mk IV http://www.adireaudio.com/Files/OldAdireDrivers.pdf
MCM 55-2241 8" http://www.mcminone.com/product.asp?catalog_name=MCMProducts&product_id=55-2421 (i'm hoping this might work due to its good performance / small size)
I also have a vintage (low qts) university C-15W 15" but I don't have the space to build something for that big a woofer.
Also,can a TH be folded? .. see my rendering for an idea of what I'm talking about (the front plates are ideas i had for putting an extra load on the driver).
Thanks
An externally hosted image should be here but it was not working when we last tested it.
Hi GM
I was just about to switch the PC off, long hours at work blah, just checked in . . it's > 1 am so I'll be brief
Thanks again for your last few posts (I'll read them when I'm more awake . . )
Following your rap, I looked into BLHs. There'll always be different perspectives, but I read in the FAQ at www.Speakerplans.com, Rob Mogale opines
"the output from the front of the driver is out of phase from the output of the horn or rear of the driver. This causes a dip in the frequency response, for 15 or 18" bins normally around the 70 to 90 Hz. It is in this 70 to 90 Hz range that we hear or feel the kick or speed of the bass.
Most scoop bins have a 3 to 6 dB dip in the response around that area making the cabinet sound slow and heavy. Scoops lack any real punch and detail and are very difficult to mix a band on. Bigger scoops with 21" drivers will have the dip lower down at around 50 to 60 Hz and the dip in response will be less pronounced with the more cabinets you use.
I much prefer folded horns, as they do not have this dip and phase abnormality around the crucial 70 to 90 Hz range. Folded horns are capable of reproducing the music very accurately and exposing a lot of detail, detail you would just not hear with a scoop bin."
I recall you referred to “perfect” BLHs, is there a way to overcome what Rob is referring to/ could comment on the above?
Cheers
I was just about to switch the PC off, long hours at work blah, just checked in . . it's > 1 am so I'll be brief
Thanks again for your last few posts (I'll read them when I'm more awake . . )
Following your rap, I looked into BLHs. There'll always be different perspectives, but I read in the FAQ at www.Speakerplans.com, Rob Mogale opines
"the output from the front of the driver is out of phase from the output of the horn or rear of the driver. This causes a dip in the frequency response, for 15 or 18" bins normally around the 70 to 90 Hz. It is in this 70 to 90 Hz range that we hear or feel the kick or speed of the bass.
Most scoop bins have a 3 to 6 dB dip in the response around that area making the cabinet sound slow and heavy. Scoops lack any real punch and detail and are very difficult to mix a band on. Bigger scoops with 21" drivers will have the dip lower down at around 50 to 60 Hz and the dip in response will be less pronounced with the more cabinets you use.
I much prefer folded horns, as they do not have this dip and phase abnormality around the crucial 70 to 90 Hz range. Folded horns are capable of reproducing the music very accurately and exposing a lot of detail, detail you would just not hear with a scoop bin."
I recall you referred to “perfect” BLHs, is there a way to overcome what Rob is referring to/ could comment on the above?
Cheers
Greets!
.........and you can screw up a BR alignment just as bad in its own way. Here's a JBL BLH (aka scoop bin (at least what they were like originally), or as I like to call them, big vent reflex (BVR)): http://www.lansingheritage.org/html/jbl/specs/home-speakers/1957-c40.htm
http://gallery.audioasylum.com/cgi/...session=&&moniker=RCA-fan&invite=&w=800&h=500
Where's the big bad dip in the red trace, unless you want to call its rising response due to the horn being too small a 'dip'? FWIW, the steeper the rise, the 'faster' it should sound since the harmonics are higher in amplitude than the fundamental.
Anyway, I'm just an old opinionated cut n' try DIYer whose 'street creds' are limited to the few simple designs folks have built/reviewed on-line whereas Bill Woods (RCA-fan) is a long time successful pro speaker/horn designer, so I'll defer to his opinion of its sonic capabilities (or lack of) and the other alignments that's been bandied about along with driver recommendations.
GM
.........and you can screw up a BR alignment just as bad in its own way. Here's a JBL BLH (aka scoop bin (at least what they were like originally), or as I like to call them, big vent reflex (BVR)): http://www.lansingheritage.org/html/jbl/specs/home-speakers/1957-c40.htm
http://gallery.audioasylum.com/cgi/...session=&&moniker=RCA-fan&invite=&w=800&h=500
Where's the big bad dip in the red trace, unless you want to call its rising response due to the horn being too small a 'dip'? FWIW, the steeper the rise, the 'faster' it should sound since the harmonics are higher in amplitude than the fundamental.
Anyway, I'm just an old opinionated cut n' try DIYer whose 'street creds' are limited to the few simple designs folks have built/reviewed on-line whereas Bill Woods (RCA-fan) is a long time successful pro speaker/horn designer, so I'll defer to his opinion of its sonic capabilities (or lack of) and the other alignments that's been bandied about along with driver recommendations.
GM
Here is a photo of the second TH,14"wide,so it will fit between wall studs or floor joists.Will have to wait for the glue to dry before I can close it up,and see how it does...
Then on to the folded version...
http://img245.imageshack.us/img245/8374/14inchtappedhorn0049bn7.jpg
Then on to the folded version...
http://img245.imageshack.us/img245/8374/14inchtappedhorn0049bn7.jpg
A 90" tall Karlson....Kool!!!
I finished the horn last night,haven't had time to do extensive evaluation,but seems to sound pretty much like the original.
external dimensions 14"x18"x90"
Only 3 dimensions were changed,the internal baffle width from 14" to 12.5",baffle spacing from 4" to 4.5",and mouth from 12" to 13.4" to keep area the same.I'm in new territory here,just assuming that's the way to do it.
Two of these really kick butt for HT... I watched War of the Worlds,and Terminator 3 last night...the house was a'shakin'!..
Here's the plans:
http://img236.imageshack.us/img236/5929/tappedhornplans002kn5.jpg
I finished the horn last night,haven't had time to do extensive evaluation,but seems to sound pretty much like the original.
external dimensions 14"x18"x90"
Only 3 dimensions were changed,the internal baffle width from 14" to 12.5",baffle spacing from 4" to 4.5",and mouth from 12" to 13.4" to keep area the same.I'm in new territory here,just assuming that's the way to do it.
Two of these really kick butt for HT... I watched War of the Worlds,and Terminator 3 last night...the house was a'shakin'!..
Here's the plans:
http://img236.imageshack.us/img236/5929/tappedhornplans002kn5.jpg
hey Don - KenL's K with 65" tall slot from ~1994 is the largest coupler shown to date (besides K's 12ft klam) - if was 19x19x66.5 then about same bulk as your TH
KenL's tractrix slot calculator
http://hometown.aol.com/klehma/
comment
http://snippets.org/pipermail/diyspeakers.new/2002-January/004482.html
KenL's tractrix slot calculator
http://hometown.aol.com/klehma/
comment
http://snippets.org/pipermail/diyspeakers.new/2002-January/004482.html
GM
(A combination of terms new to me, eg when you said “DBR = double bass reflex”, I thought you meant two woofers in one box – but now see it’s a bandpass; my ISP throttling me back to dial up speed; little time for a coupla days; and thinking one of your sims was in response to Freddy had me confused).
Anyhow ~
> A 'perfect' BLH is so well damped that it has no output above the driver's mass corner, and its sheer size so completely controls the driver that it physically delays its radiating output ('tail wagging the dog') . . In a sim, its impulse response is so straight/sharp it makes a 0.5 Qtc sealed's look like a vented's, relatively speaking
Perfection is being a little optimistic , but how do you avoid a midbass (ie not trying to plumb the depths) BLH being highly compromised, in particular – with minimal dip? - a larger chamber?
The baffle step could be handled by a circuit, and if the scoop were only used above the zone of room gain, things are simplified.
your post #145
> L = 31.375"
CSA = 640"^2 (suggest 32.187" w x 19.875" d)
driver at extreme top
vent at extreme bottom with a 640"^2 area,
so full width x 19.875" high
the driver is at the extreme top ~ of the baffle? is the baffle any particular size?
L is the length of the “line” ~ which can be any shape without extreme bends?
CSA?
And is the compression ratio any particular value?
And in the BLH sim, what are the red and blue lines?
Rather than answer the questions re the specific design, are there formulae you can post which I or others can use with different drivers etc?
Thanks again
(A combination of terms new to me, eg when you said “DBR = double bass reflex”, I thought you meant two woofers in one box – but now see it’s a bandpass; my ISP throttling me back to dial up speed; little time for a coupla days; and thinking one of your sims was in response to Freddy had me confused).
Anyhow ~
> A 'perfect' BLH is so well damped that it has no output above the driver's mass corner, and its sheer size so completely controls the driver that it physically delays its radiating output ('tail wagging the dog') . . In a sim, its impulse response is so straight/sharp it makes a 0.5 Qtc sealed's look like a vented's, relatively speaking
Perfection is being a little optimistic
, but how do you avoid a midbass (ie not trying to plumb the depths) BLH being highly compromised, in particular – with minimal dip? - a larger chamber?The baffle step could be handled by a circuit, and if the scoop were only used above the zone of room gain, things are simplified.
your post #145
> L = 31.375"
CSA = 640"^2 (suggest 32.187" w x 19.875" d)
driver at extreme top
vent at extreme bottom with a 640"^2 area,
so full width x 19.875" high
the driver is at the extreme top ~ of the baffle? is the baffle any particular size?
L is the length of the “line” ~ which can be any shape without extreme bends?
CSA?
And is the compression ratio any particular value?
And in the BLH sim, what are the red and blue lines?
Rather than answer the questions re the specific design, are there formulae you can post which I or others can use with different drivers etc?
Thanks again
One thing I have found when simulating the tapped horn in hornresp is that most prodrivers have way to low mass to be any usefull. I think even the Eminence LAB 12 driver has to weak motorsystem and too low mass. I just simulated a huge tapped horn with two Ciare 18.00 SW driver in an isobaric configuration. (face to face).
It looks something like this:
Notice how the two peaks are quite similar in amplitude. That is with 720 gram mass and a BL of 61!!!!
It looks something like this:
An externally hosted image should be here but it was not working when we last tested it.
Notice how the two peaks are quite similar in amplitude. That is with 720 gram mass and a BL of 61!!!!