Ladies & Gentlemen - The Emken

[sippy]

If space is tight a smaller pre-existing design could be better suited, as even the skinniest boxes for a 12" is going to be 12" in width.
Having said that, what a visual statement this idea would make..... tweeter in a pod, 12Lta wide range and the 'EmKen' as LF support.
I'm in town tomorrow and will check on progress of the cutting, am begging to think I should have bought a saw and a decent blade as I already have a 11ft strait edge and done the cutting myself.

 

[GM]

To accomodate his space I would like to make a narrower version of the EmKen that utilize a larger "cylindrical head" to accomodate the actual driver. This head would be open to the tower base internally. My question is, are these types of alignments changeable assuming you maintain the volume and vent space?

Depends on the configuration and in this case, not really, at least in theory since you've created a double bass reflex [DBR] where a small net Vb is reflex vented with a very large, long ~aperiodic vent. Seems to me it would perform pretty much like an acoustically tiny, well stuffed, sealed cab, but AkAbak should be able to sim it good enough to find out.

GM

 

[ebag4]

Guys, thanks for the replies. The drawing is just conceptual. I don't know what the vent or volume requirements are just yet. I believe the head can be made to avoid and restiction to the lower box. This pair will likely be taller than would be typical, they are slotted for a bedroom and most of the listening will be done while on the bed. Between the volume of the head area and the additional height I should be able to make the dimensions work for the volume, what I don't have a clue about is the impact on the vents, are they measured in cubic inches?

I will be listening to the drivers first, it is possible I will decide not to go any further with them, but from what I have read they sound like a fun driver.

Thanks guys,
Ed

 

[GM]

Guys, thanks for the replies. what I don't have a clue about is the impact on the vents, are they measured in cubic inches?

You're welcome!

Not per se, vent area [Av] sets the basic parameter for a given net volume [Vb] and vent length [Lv] sets tuning frequency, so if the net Vb is the same, then in theory the vent design is the same for a given desired tuning frequency [Fb], i.e. simple Helmholtz resonator.

This assumes the Vb has a ~uniform particle density in the tuning BW though, so as one dimension becomes long enough to have ¼ WL damping on the vent, its length shortens and in some cases will be reduced enough to the point where a larger Av must be used.

In the Fonken’s case though, the vents are distributed along its entire length plus will have additional damping, so will average out its acoustical loading enough to ~negate any ¼ WL loading; ergo maintain the same net Vb, damping scheme and distribute the same vent system along its length and the driver’s offset to the top should have only a minimal impact as long as there’s no abrupt volume transitions.

GM

 

[Vix]

Ed, if you do make this design, I can't resist naming it: EMKenny

Paint it orange and it will be Big Fun speaker

 

[JRKO]

I can't resist naming it: EMKenny

'mm mmm m mm mm mmmm' - Kenny says it needs a furry fringe

'dude! you said it needs a furry fringe!!'

Cartman says something I cant put on DIYAudio.......

 

[Godzilla]

Haven't listened to my 12lta's in weeks! They are now at my parents house rather than in my basement. Most of my listening has been done on Sony earbuds and my iPhone.

An earbud thread might be fun. They vary drastically from brand to brand even tho the reaearch i've done indicates they are all the same... they don't sound the same to me. And they certainly don't sound like the Beta 12lta.

 

[JRKO]

Hey Zilla. Glad you've been able to rehouse your 12LTA's. Hope life isn't being too stressful for you.

For a great budget headphone rig I use Superlux HD660 (closed black) or Superlux HD668B (open back). These are powered by JDSLabs Cmoy which is battery powered and takes a line out from the dock connector. For listening at my desk I use an Audiotrak Imamp. I prefer the 668B sound but use the 660 when there is more background noise.

James

 

[ebag4]

I have received my drivers and after listening to them in free air a bit I believe they will make for a nice speaker with a little help on top. I would like to build a speaker that does not "have" to have a sub, so getting decent output down to 40 hz or a bit lower is the plan. I have looked at the Hammer Dynamics speaker using a similar driver. Here is my question, what does the "EmKen" type speaker do better than a BR type speaker such as the HD unit?

The reason I ask is because I believe I could build a BR speaker with about 4 cuft of space and I can build it a bit more narrow and deeper than what the EmKen appears to be, this would allow it to fit into my space a bit better.

I also have a question concerning the super tweeter placement, I have seen designs such as the ZUs that use a full range driver with the tweeter sitting well below the full range. I thought (likely mistaken) that I had read the acoustic centers of the drivers should be within a wavelength of the crossover point (e.g 4500~3"), is this not true for super tweeters? Does the higher crossover point make this less of an issue?

BTW Vix, if I do end up building a speaker similar to what I sketched up, I believe the EMKenny is the prefect name , orange would work since his room is painted orange and black for the Cincy Bengals!

Best,
Ed

 

[planet10]

Here is my question, what does the "EmKen" type speaker do better than a BR type speaker such as the HD unit?

The high aspect ratio vents add an "R" to the vent increasing their tolerence to dynamic shifts in T/S parameters (ie they have a greater range under which the box remains in tune).

The reason I ask is because I believe I could build a BR speaker with about 4 cuft of space and I can build it a bit more narrow and deeper than what the EmKen appears to be, this would allow it to fit into my space a bit better.

Em-Ken is based on 120 litre. Vents do not need to be on the siides.

I thought (likely mistaken) that I had read the acoustic centers of the drivers should be within a wavelength of the crossover point (e.g 4500~3"), is this not true for super tweeters? Does the higher crossover point make this less of an issue?

Ideally within a 1/4 wavelength C-C. Tweeter would need to be co-axially mounted to get that. As the XO frequency goes up the ear-brain seems to be less affected by the inevitable combing.

dave

 

[ebag4]

Thanks for the informative responses Dave, much appreciated. What really caught my attention is the fact that the vents do not have to be on the sides, this would help greatly with regard to my project. Assuming the vents were located on the bottom, it would stand to reason (at least to me) that a vent across the bottom would likely have to be larger to be equivalent to the side vents, am I on the right track?

Have there been any measurements of the bass response for this driver in the Emken alignment? I read where you stated the F3 was projected to be @ 55 Hz and the F10 @ 40, was this where the measurements fell in testing?

Given the ability to place the vent in the bottom, this has become a viable project for my situation.

Thanks again,
Ed

The high aspect ratio vents add an "R" to the vent increasing their tolerence to dynamic shifts in T/S parameters (ie they have a greater range under which the box remains in tune).



Em-Ken is based on 120 litre. Vents do not need to be on the siides.



Ideally within a 1/4 wavelength C-C. Tweeter would need to be co-axially mounted to get that. As the XO frequency goes up the ear-brain seems to be less affected by the inevitable combing.

dave

 

[ebag4]

If space is tight a smaller pre-existing design could be better suited, as even the skinniest boxes for a 12" is going to be 12" in width.
Having said that, what a visual statement this idea would make..... tweeter in a pod, 12Lta wide range and the 'EmKen' as LF support.
I'm in town tomorrow and will check on progress of the cutting, am begging to think I should have bought a saw and a decent blade as I already have a 11ft strait edge and done the cutting myself.

Hi Sippy,
I just reread your post. What pre-existing designs are you referring to?

Thanks!
Ed

 

[sippy]

For the 12lta?
Well, I dont know if you'll find many speakers smaller than the EmKen unless you go for a recommended box size from Eminence or design one your self.
There are a few designs/kits out there that use Eminence drivers, one might take a look at Pi Loudspeakers (with whom I have no affiliation, other than having 2 plan sets) offer such,
none are small though.

 

[ebag4]

Thanks for the reply Sippy.

Here is a potential candidate for me assuming I can get the vents the correct size. This is based on the 120 Liter value Dave mentioned earlier. The internal dimensions of the main cabinet are 8"x19"x48" for 4.23 cuft. The vents are 3/4" across and it is based on 3/4" Birch ply. In this scenario the vents would only go up to the bottom of the driver. No idea how far back the internal side would be off of the back. I believe I could build this using 2 4x8 sheets. Any comments?

Thanks,
Ed

 

[ebag4]

Gents,
I just happen to think that I may be getting pretty far OT with my questions, what I am trying to do may no longer fit in the EmKen thread. Moderator, please feel free to move my posts to a separate thread if you feel it is necessary.

Best,
Ed

 

[JRKO]

Main thought is that the 12lta is really close to internal walls including the ring you're using to mount the large driver to the narrow box.

By my math if your cabinet is 10" externally you loose 3/4 for the inner wall, 3/4 for the vent and 3/4 for the outer wall for each side or 2.25" - so your internal volume is 10" ext width minus 4.5" = 5.5" x 19" x 48" = 82.2L (there are 3 parts to each side wall. The outer, the ribs and the inner wall)

You could still use these dimensions and add the 'Kenny' pod on top to sort out the proximity and volume problems

Best of luck with the EmKenny - dont forget that the 12lta works well in a smaller sealed box too. Look for Godzilla's thread on the subject

J

 

[ebag4]

Main thought is that the 12lta is really close to internal walls including the ring you're using to mount the large driver to the narrow box.

By my math if your cabinet is 10" externally you loose 3/4 for the inner wall, 3/4 for the vent and 3/4 for the outer wall for each side or 2.25" - so your internal volume is 10" ext width minus 4.5" = 5.5" x 19" x 48" = 82.2L (there are 3 parts to each side wall. The outer, the ribs and the inner wall)

You could still use these dimensions and add the 'Kenny' pod on top to sort out the proximity and volume problems

Best of luck with the EmKenny - dont forget that the 12lta works well in a smaller sealed box too. Look for Godzilla's thread on the subject

J

Well, I have the exterior dimension at 10.5" but you are right, I managed to forget to add the exterior 1.5" for the outer sides, duhhh. Back to the drawing board!

Taking another look at it, I have the exterior dimension, I simply mislabled it as 10.5 instead of 12.5". This gives me 8" internal width+ 1.5" for 9.5" inner box width+ 1.5" for ribs taking it to 11" and the outer walls for an additional 1.5" taking the entire width to 12.5". I think you are likely correct regarding the side wall being too close to the driver.

Best,
Ed

 

[sippy]

According to my cad layout, EmKen will come out of 2 sheets 8'x4' minus a little bit of bracing...... mine seem to be waiting for a divine wind or some thing

 

[JRKO]

wow are you still waiting on the cuts Sippy? Thats a pain

And for my mid month 'any tests yet guys?' - Quit designing & playing with those cute little mini monkey coffins will ya?

 

[planet10]

And for my mid month 'any tests yet guys?' - Quit designing & playing with those cute little mini monkey coffins will ya?

It is hard to get excited with the little teeny tiny miniOnken sounded sooo much better than our EmKen

Also, laptop failure (new motherboard required), and diyFEST prep they keep falling in the queue. I would like to get at least a coat of puzzlecoat on them so i have to do it soon

dave