Visaton open baffle project idea, opinions?

[Fraggle]

The "volume increase factor" should be set to 1 according to Boxsim FAQ11 for open baffle simulation. It does make a difference. As UweG said, no error will result as long as you use the most recent driver files, which are supplied with Boxsim 2.0. Driver updates can be found here.

The directivity peak around 500 Hz could be reduced by moving the woofers closer to the AL130M.

The continuous power handling of the BF32 is only 2 Watt which is a bit worrying. A higher crossover would be safer.

[DaveFred]

The "volume increase factor" should be set to 1 according to Boxsim FAQ11 for open baffle simulation. It does make a difference. As UweG said, no error will result as long as you use the most recent driver files, which are supplied with Boxsim 2.0. Driver updates can be found here.

Thank you for pointing me to the updated drivers. I am now using the new WS25E that does not get the error when the "volume increase factor" is set to 1.

[sobi]

Alternative zum BF32:
http://www.visaton.de/index.php/en/p.../frs-5-x-8-ohm
Belastbarer und höherer Wirkungsgrad, vorallem im Hochtonbereich...

[DaveFred]

Update Aug 1, G25FFL in Waveguide

Hello there,

I have made a few changes to the design. I changed to the G25FFL in a wave guide for a tweeter and changed the baffle to a 2.5 cm flat panel with a smaller narrow baffle above it for the mid and the tweeter.

Here are the measurements,

If the real speaker is anything like the simulation, this looks very very good.

All crossover values are actual values that can be purchased at a store with correct resistance.

The directivity is incredible
(Die Direktivität ist unglaublich)

Do you think the real speaker will be anything like this when built?

[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

[DaveFred]

nlcarbon,

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

[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]

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.

[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.

[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.ph...1&postcount=15
zum beispiel

[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.

[walwal]

Ok, have fun and succes.

[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?

[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.

[walwal]

Exactly, as i wrote in # 24