Beta 12LTA in a 3cf box - port size - Page 4

GM · 23rd December 2010, 05:25 AM

Quote:

Originally Posted by Godzilla

GM, thanks......

Do you really think it will add to the bloated sound if on the bottom?

Anyone have any thoughts on aperiodic and how it extends response?

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.html

In 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

JRKO · 23rd December 2010, 10:26 AM

Quote:

Originally Posted by bassrogue

Nice to see interest in the Beta 12

I spy a phase plug and EnABL dot thingys

Can you tell me what difference the phase plug makes? Also the EnABL pattern?

Godzilla · 23rd December 2010, 01:20 PM

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.

JimW · 23rd December 2010, 01:53 PM

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.

JRKO · 23rd December 2010, 02:02 PM

Quote:

Originally Posted by Godzilla

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...

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. 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!

Details to come.

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

bassrogue · 02:32 PM

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.

Vix · 23rd December 2010, 03:28 PM

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

Godzilla · 23rd December 2010, 05:27 PM

>>> 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

bassrogue · 23rd December 2010, 05:35 PM

Quote:

Originally Posted by Godzilla

>>> 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

I forgot about the Damar on the whizzer, did that also

Godzilla · 23rd December 2010, 05:45 PM

>>> I forgot about the Damar on the whizzer

Thanks bassrogue! Did you notice anything different? I am going to do one driver up with tweaks and offer subjective opinions since i have no measuring gear other than my ears. This is DIY, who wants stock drivers anyway, LOL.

23rd December 2010, 02:25 PM	#36
bassrogue diyAudio Member Join Date: Mar 2006 Location: Yelm, WA	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. __________________ Just once I wish someone would call me "Sir" without adding, "you're making a scene" Last edited by bassrogue; 23rd December 2010 at 02:32 PM.

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23rd December 2010, 01:20 PM	#33
Godzilla diyAudio Member Join Date: Nov 2005 Location: New York	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.

23rd December 2010, 01:53 PM	#34
JimW diyAudio Member Join Date: Oct 2004	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.

23rd December 2010, 03:28 PM	#37
Vix diyAudio Member Join Date: Nov 2003 Location: Somewhere on Planet Earth	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

23rd December 2010, 05:27 PM	#38
Godzilla diyAudio Member Join Date: Nov 2005 Location: New York	>>> 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

23rd December 2010, 05:45 PM	#40
Godzilla diyAudio Member Join Date: Nov 2005 Location: New York	>>> I forgot about the Damar on the whizzer Thanks bassrogue! Did you notice anything different? I am going to do one driver up with tweaks and offer subjective opinions since i have no measuring gear other than my ears. This is DIY, who wants stock drivers anyway, LOL.