Visaton open baffle project idea, opinions?

[jama]

0,33 uF attenuates W25E resonance by 2500 Hz

[walwal]

[UweG]

The coordinate system that is used to define the position of the sound output has to be the same for all drivers. In this coordinate systems the different distances to the microphone are calculated in the several angles.
If the common outer housing is used (for any of the chassis) the center of the common outer housing is defined as 0,0,0. If the common outer housing is not used, you can define the center where ever you want.

For the project attached to #19, the sketch in #23 is correct relating to positions. I would have preferred to define the common out housing with the complete height and only adapt the with of the baffle.
Based on the project from post #19 it looks like the attached project file.
The difference in output is not very big, the truth might be anywhere in between those two simulation.

[nlcarbon]

1. Formally, the settings posted by DaveFred in #23 represent the drawing correctly.

The note in Boxsim says: "If common outer housing is used, 0,0,0 is the center of the common front side baffle."
(@nlcarbon: In my opinion, this means the center of the large baffle and NOT the small baffle.)
We are using a common housing here, and its center is 40 cm above the floor.
Therefore, y = 52.5 cm places the AL130 at 92.5 cm above the floor.

I don't think so! In my opinion it is the small baffle from the driver you are woking on. So the correct vertical Position in Room must be 72,5cm.

Maybe UweG can "bring light into the dark"

But for simulation it is more correct to use the 120x15cm instead of 40x15 baffle for AL + G25 as already said.

Edit: If iam correct I also have a mistake in my simulation #20. The horizontal position in room of the Al and G25 must be 7,5cm instead of 0 because of the 15cm smaler baffle...

[walwal]

Exactly, as i wrote in # 24

[Fraggle]

I think we have to distinguish two different points.

1. Formally, the settings posted by DaveFred in #23 represent the drawing correctly.

The note in Boxsim says: "If common outer housing is used, 0,0,0 is the center of the common front side baffle."
(@nlcarbon: In my opinion, this means the center of the large baffle and NOT the small baffle.)
We are using a common housing here, and its center is 40 cm above the floor.
Therefore, y = 52.5 cm places the AL130 at 92.5 cm above the floor.

2. Acoustically, there is only one baffle with a special shape.
As Boxsim cannot simulate this case accurately, the resort is giving each driver a recangular baffle that comes close to the real situation.
Therefore, 15 x 120 cm for the midrange and tweeter, and a 30 x 80 cm for the woofers seems reasonable.

Keep in mind you are only using a "trick" to simulate the open baffle. Boxsim does not have measured frequency response data for the rear side of the speaker. It does not even know the size of the radiating area on the rear side. So I am not sure how accurate the simualation can be.

[DaveFred]

From what I posted in #23, I take it my settings don't match my drawing.

Where in space is my tweeter and midrange with my settings? In front of the woofers?

[walwal]

Ok, have fun and succes.

[DaveFred]

But, the combination of 3 speakers in open baffle with 1 Tweeter + waveguide is very curios. If you like the sound of those dipolspeakers, also the tweeter should be a dipol. Or install a second tweeter on the back for example.

Very good question.

Every year a local club has a friendly speaker building contest (no prizes, just for fun). The rules are set up so that the build is not a normal straight forward design. This year is "front and rear radiation". The speaker does not have to be a true dipole, but there has to be rear radiation for several mid octaves. The rules allow for woofers up to 30cm, can only be a three way crossover, no wide band/full range for tweeter, up to 38cm wide by 120 cm tall baffle. The maximum budget allowed is ~$500 Euro for drivers. There is a whole page of rules, but those are the main ones that explain the odd design I am working with.

So I am looking to build a hybrid.

[jama]

But, the combination of 3 speakers in open baffle with 1 Tweeter + waveguide is very curios. If you like the sound of those dipolspeakers, also the tweeter should be a dipol. Or install a second tweeter on the back for example.

oder BF32 nehmen als tweeter ^^

http://www.visaton.de/vb/showpost.php?p=448561&postcount=15

zum beispiel

[walwal]

Step 1:



Step 2:


Step 3:



Same with speaker 4...

This ist just a simulation and not the reallity, you have to measure it or... try and error...

But, the combination of 3 speakers in open baffle with 1 Tweeter + waveguide is very curios. If you like the sound of those dipolspeakers, also the tweeter should be a dipol. Or install a second tweeter on the back for example.

[DaveFred]

Thats right, but I think you have a mistake in the driver height. The AL in your project is on 52,5cm in vertical axis + 20cm (the middle of the small 40cm baffle). So Total 72,5cm. That doesn't fit with a WS25 on 60cm.

The second is that a "more correct" baffle to calculate for the AL an G25 is 120x20 for exaple not 40x20. Because the drivers "see" the baffel from the WS25...

Here is from the box where you enter the data,

"Position of sound output in xyz coordinates"

"If common outer housing is used, 0,0,0 is the center of the common front side baffle. Positive values = right or top"

I thought that meant that if my common baffle is 80cm tall, and I wanted the AL130 to be at 92.5cm Y, that would be 1/2 of common baffle height (40cm) + 52.5cm.

Am I not understanding how the baffle layout works?

I have attached a quick sketch I made.

Thank you,

David.

[nlcarbon]

Thats right, but I think you have a mistake in the driver height. The AL in your project is on 52,5cm in vertical axis + 20cm (the middle of the small 40cm baffle). So Total 72,5cm. That doesn't fit with a WS25 on 60cm.

The second is that a "more correct" baffle to calculate for the AL an G25 is 120x20 for exaple not 40x20. Because the drivers "see" the baffel from the WS25...

[DaveFred]

nlcarbon,

I thought I was placing a small baffle above the large baffle with the settings.

[nlcarbon]

The Positions of the AL an G25 on the Baffle are wrong!

-firt you have to place all drivers in correct Position (option common outer housing) on a baffle with an heigt of maybe 110cm and 30cm width.
-then you can type in a thinner baffel for the AL and G25 on (enclonsure and baffle)
-at least you can type in a lower baffle for the ws25...

It would never be 100% correct because Boxsim didn't know that the baffel under the AL grow from 15cm width to 30cm... Or in the other way that over the WS25 the baffle is 15cm...

Here is the Project as I think its more correct.
Regard Nils