I suspect it's a box design that was on the (defunct) vintage Electrovoice geocities site. IIRC, it was a fairly simple folded pipe with a Karlson / Fulmar slot forming the terminus.
Scottmoose,
I know you are quite busy lately, but..since I know your contribution toward creation of Half-Chang, and that is was very nice sounding, successful design, I was thinking if you could help Jeff create something like Beta-Half-Chang? I guess that it should sound better than sealed or a simple ported box...
Thanks
Vix
I know you are quite busy lately, but..since I know your contribution toward creation of Half-Chang, and that is was very nice sounding, successful design, I was thinking if you could help Jeff create something like Beta-Half-Chang? I guess that it should sound better than sealed or a simple ported box...
Thanks
Vix
'Bloat' is a tuning 'thing', so if anything, bottom venting will tend to make it worse if not firing into a very dense absorber which will of course 'catch' some of the vent's fundamental output, i.e. lower the vent's Q toward aperiodic, spreading it over a wider BW same as the Fonken series. The easy cure then is to either lower its tuning and/or increase cab, vent damping to 'taste'.
GM
Scott, please don’t spend time designing a Beta 12 Half Chang for me! In the end I will build whatever suits my space. I emailed you and Dave about designs that may have already been done just to satisfy my curiosity. The Maria looks interesting but is much too large for my office. Besides, if I wanted large I would emulate the 12lta BIB someone else did that must be incredible to listen to! I can never find the thread tho.
Thanks for trying Vix, lol.
GM, thanks, i am thinking aperiodic for sure! For my space a 2.5cf box is about the right size. I like the sim curve sealed in 2.5 but not so much the ported. I was thinking of building it ported but stuffing to taste (probably heavily, bringing the response closer to sealed) but with some breathing room for the driver. I was thinking about treating the bottom firing port as an aperiodic vent but in an effort to avoid the dreaded bloat. Do you really think it will add to the bloated sound if on the bottom? Maybe i will consider moving the port to the rear instead. I liked the idea of porting out the bottom and using caster wheels to assist in moving the speakers around and as a spacer to the floor. Anyone have any thoughts on aperiodic and how it extends response? Probably not much. Badman did something interesting with B20s in small boxes that looked interesting to me that was aperiodic in nature.
Thanks!
Thanks for trying Vix, lol.
GM, thanks, i am thinking aperiodic for sure! For my space a 2.5cf box is about the right size. I like the sim curve sealed in 2.5 but not so much the ported. I was thinking of building it ported but stuffing to taste (probably heavily, bringing the response closer to sealed) but with some breathing room for the driver. I was thinking about treating the bottom firing port as an aperiodic vent but in an effort to avoid the dreaded bloat. Do you really think it will add to the bloated sound if on the bottom? Maybe i will consider moving the port to the rear instead. I liked the idea of porting out the bottom and using caster wheels to assist in moving the speakers around and as a spacer to the floor. Anyone have any thoughts on aperiodic and how it extends response? Probably not much. Badman did something interesting with B20s in small boxes that looked interesting to me that was aperiodic in nature.
Thanks!
Would you mind sharing those sim curves? No windows machine and cant find a decent modelling program (for free
)
Thanks Godzilla. Goodness me that 10cb ft is flat to 40Hz
10cb ft is not that big - for home use. you probably wouldn't fit in your office!!
I was REALLY wanting to have some 15 inchers for bass duty
but I dont know if I'll need them with that size cab.
Of course for Higher Fi the 2.5cb ft makes more sense and then I can raise hell with a 15
10cb ft is not that big - for home use. you probably wouldn't fit in your office!!
I was REALLY wanting to have some 15 inchers for bass duty
but I dont know if I'll need them with that size cab.Of course for Higher Fi the 2.5cb ft makes more sense and then I can raise hell with a 15
You're welcome!
Not if you damp it as I suggested.
Anyway, a down-firing vent is a pistonic radiator same as a woofer WRT acoustic loading and how floor loading affects tuning, so maybe this will help with this subject: http://www.acmebass.com/science/downwoof/downwoof.htmlIn the same vein, damping towards aperiodic lowers the effective Fs and Qb for a wider BW with a higher F3 than the same vented alignment with minimal damping, i.e. effectively a near sealed alignment with more gain BW. Taking this to its logical extreme, it morphs into a stuffed TL.
GM
I spy a phase plug and EnABL dot thingys
Can you tell me what difference the phase plug makes? Also the EnABL pattern?
Bassrouge, that's the idea! I love the way your speaker looks!
Questions:
Prior to adding phase plugs, did you listen to the 12lta after cutting off dustcaps? If you did, did you notice an improvement?
How did phase plug change the sound?
Where are you rolling in the tweeter?
Thanks everyone for your input! I cut wood last night... decided to go sealed with a sub... three 2.5 cubic foot boxes exactly the same size... I was not satisfied with the sims unless going to 4cf like the Hammer Dynamics box (which looks like a really good overall compromise) or larger. I went with three smaller boxes rather than two large and will play around with positioning.
Imagine three of these Zu Audio - Omen - Standard
Two with 12lta near the top of the cabinets and one with a powered sub near the bottom... i just liked the sims of the sealed boxes best (tho bass extension was limited) and am excited to add an all sealed set of speakers to my collection! The powered sub should get me down near 35hz in my medium sized room (approx 13 x 16 with 11 foot ceilings). On their own the 12lta would manage around 65hz... that's not enough bass but i am hopeful what's there will be punchy and dynamic.
I DO feel like cutting up the 12lta! Seeing all that cardboard near my Xacto knife is so tempting!
Details to come.
Questions:
Prior to adding phase plugs, did you listen to the 12lta after cutting off dustcaps? If you did, did you notice an improvement?
How did phase plug change the sound?
Where are you rolling in the tweeter?
Thanks everyone for your input! I cut wood last night... decided to go sealed with a sub... three 2.5 cubic foot boxes exactly the same size... I was not satisfied with the sims unless going to 4cf like the Hammer Dynamics box (which looks like a really good overall compromise) or larger. I went with three smaller boxes rather than two large and will play around with positioning.
Imagine three of these Zu Audio - Omen - Standard
Two with 12lta near the top of the cabinets and one with a powered sub near the bottom... i just liked the sims of the sealed boxes best (tho bass extension was limited) and am excited to add an all sealed set of speakers to my collection! The powered sub should get me down near 35hz in my medium sized room (approx 13 x 16 with 11 foot ceilings). On their own the 12lta would manage around 65hz... that's not enough bass but i am hopeful what's there will be punchy and dynamic.
I DO feel like cutting up the 12lta! Seeing all that cardboard near my Xacto knife is so tempting!
Details to come.
I have been using a pair of these in 5.5 cf boxes in my office for several years. They were "afterburner" inspired. The cabs are 20w, 44h, 14d with a four inch x .75 port on the lower back. I did the damar varnish, clay on the baskets (ring like bells otherwise), and had planet ten make phase plugs. The difference with and without phase plugs is subtle, but noticeable in upper mid range. I am using fostex ft17 tweeter on top of the cabs. The drivers are positioned at the top of the cabs, at about ear level. I found they need a notch filter to minimize the upper shoutiness, the original afterburner article gives a design. They are very easy to drive (I am using a 1626 darling amp), quite dynamic, and have good bass, even at low levels. The down side they have a nasal quality. If you are not doing a-b comparisons, it really isn't that noticeable.
I'm gonna join ya
Selling some bits to release some funds and I'll be all over it!!!!
Let me know how you do with the dustcap. I've asked Dave (Planet10) to see if he can give me some measurements of a set he has in some 12LT's
I do believe the phase plugs make difference though maybe not as much as with the 8" Fostex that I own. I also made a pair of plugs with the 5/8" Dayton tweeter mounted on the end. This worked fairly well also but the tweeter needed to be more efficient to match the Beta 12.
The "enable dot thingys" were a shot in the dark and I'm not sure if they made a difference one way or the other. I got the pattern from Daves website.
There is also some stuffing between the whizzer cone and the main cone. This did help take some of that shout away. The combination of all three made the Beta 12 more relaxed in the upper mid range and easy to listen to.
The tweeter is an old Pyle compression horn that I've had laying around for years. It's efficient enough to be a good match and fairly smooth. I have it crossed in at around 7000hz. I'd rather have the crossover closer to 10,000 but it leaves a "hole" up there and doesn't sound right.
The "enable dot thingys"
were a shot in the dark and I'm not sure if they made a difference one way or the other. I got the pattern from Daves website. There is also some stuffing between the whizzer cone and the main cone. This did help take some of that shout away. The combination of all three made the Beta 12 more relaxed in the upper mid range and easy to listen to.
The tweeter is an old Pyle compression horn that I've had laying around for years. It's efficient enough to be a good match and fairly smooth. I have it crossed in at around 7000hz. I'd rather have the crossover closer to 10,000 but it leaves a "hole" up there and doesn't sound right.
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Jeff, if you are going to use a sealed sub, and sometime get the desire to extend its response, you may use one of these circuits: P48 Sub-Woofer Controller (Rev-A)
Or a bit more complicated, but still doable: The Linkwitz Transform circuit
Linkwitz Transform Subwoofer Equaliser
Or a bit more complicated, but still doable: The Linkwitz Transform circuit
Linkwitz Transform Subwoofer Equaliser
>>> I'm gonna join ya...
GREAT!
Vix, thanks for the sub extension suggestions. I am hoping with three 12" woofers booming i wont need to do that.
I'm psyched to get started... boards cut (inaccurately) so the belt sander will be by my side most of the holiday. Otherwise, i expect a dynamic, large sound. The driver begs to be tweaked! The dustcap of one will come off and some acousta stuff will be gently placed around the whizzer for comparison to the stock driver. Phase plugs and circuits (i hope not circuits!) will be tried later on after i've enjoyed some music thru them! Wonder if my damar is still good? Damar reduced the shout of a piezo... wonder how it will do on the 12lta?
Zilla
GREAT!
Vix, thanks for the sub extension suggestions. I am hoping with three 12" woofers booming i wont need to do that.
I'm psyched to get started... boards cut (inaccurately) so the belt sander will be by my side most of the holiday. Otherwise, i expect a dynamic, large sound. The driver begs to be tweaked! The dustcap of one will come off and some acousta stuff will be gently placed around the whizzer for comparison to the stock driver. Phase plugs and circuits (i hope not circuits!) will be tried later on after i've enjoyed some music thru them! Wonder if my damar is still good? Damar reduced the shout of a piezo... wonder how it will do on the 12lta?
Zilla
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