Re-Built Vifa Basis 95 -> 2023

[Hondasnl]

Dear friends,

In the future I like to re-built my wonderfull Vifa Basis 95 speakers.
They sound very nice and powerfull but I don't like the design of the original cabinet.
The drivers are in very very good condition.

My plan is to design separate cabinets.
One cabinet for the bass and one for the mids and highs.
I did not change the volumes of the new cabinets as you can see.
I also did not change the baffle width of the top cabinet for the mids and highs.
What I like to check is the port dimensions of the bass cabinet.
So I'm looking for a correct data sheet of the woofers.
See also my other thread.

Specifications:

Drivers : 5x
Power handling : 360 W
Sensivity : 91 dB
Frequency respons : 25 Hz tot 25 kHz
Nom. impedance : 4 Ohm

Bass: 2x M25WP-00
Low mid: P17WJ-00
Dome: DM-760/2 / D75MX-31
Tweeter: D2905/950000

Can someone give me some advice / comments?

 

[Wik]

is that real bike on the side?

 

[planet10]

The braces in your bass enclosure could be better oriented.

Guidline 1: The subpanelcreated by a brace should have a larger aspect ratio than the panel being braced.

Guidline 2: place braces such that they do not prodcue the same aspect ratio.

dave

 

[Hondasnl]

Hi Dave what you mean with Guidline 1?
Can you explain a little bit better for me?

 

[planet10]

In you case the braces should be vertical to acheive that,

dave

 

[Hondasnl]

Hi Dave, like this if I'm understand correct?

 

[Hondasnl]

The braces in your bass enclosure could be better oriented.

Guidline 1: The subpanelcreated by a brace should have a larger aspect ratio than the panel being braced.

Guidline 2: place braces such that they do not prodcue the same aspect ratio.

dave

Revised plans.

 

[planet10]

If the holey brace is doubed and move such that they can brace each woofer against the back & sides removing a significant amount of energy from the baffle.

Given 2 woofers a very significant improvement could be mounting the woofers push-push. This will remove a significant amount of reactive energy actively greatly decreasing box vibrational load. Your XO should be low enuff that side mointed woofers will not be an issue. Further it would allow you to get teh woofers closer to the mid. In an ideal world teh C-C is less than a quarter wavelength at the XO point.

What is your woofer to lower mid XO point?

dave

 

[Hondasnl]

The holey brace is an important piece inside the cabinet.
It has his fixed position between the two volumes, 51,5 liter for the upper woofer and 54,25 liter for the lower woofer (according original design).
I don't know the XO point.
Attached the original schematic.
Is that enough to determine the XO point?

 

[planet10]

Given the size of the holes each woofer sees the whole volume. It should matter not wher eyou put it.

dave

 

[Hondasnl]

Not completely correct.
On top of this panel is "baffletex 10mm".

 

[planet10]

I do that on the holey braces i use as well. It makes no difference in whatthe driver sees as box volume.

What it does is help kill any top/bottom standing waves. But for optimal performance that it should be near half. And no reason that same could be done in a push-push box.

dave

 

[Hondasnl]

Then you have to add more holes in your panel for your design I believe.
Because for this design, the 9 holes of 73mm are not enough for these size of woofers if you want to use it only for a bracing panel.

In my case the two woofers will behave differently in this proven design.
It's more / less a restriction panel with fine-tuning possibilities.

As with the previous version of the Basis, the two woofers are each placed in a "separate" compartment.
The upper woofer behave as a bass reflex cabinet.
The volume of this is more increased because holes are made in the panel between the lower and upper compartment.
The woofer in the lower compartment therefore works partly in a bass reflex room, but still has more properties associated with a closed cabinet.
This results in a tighter bass reproduction for the lower woofer.
It is also possible to adjust the bass to your own listening room by placing more or less damping material over the holes.

 

[planet10]

8 73 mm holes have an area of 0.0335 m², about the same as the S_d of one woofer, not small enuff to cause any restriction IMO.

dave

 

[Hondasnl]

Every seperation panel with holes behave as a restriction ;-).
And if you add (more) damping material on it it will increase the restiction.

Thank you.

 

[Moondog55]

What exactly do you not like about the cabinets as they are?

 

[markbakk]

Then you have to add more holes in your panel for your design I believe.
Because for this design, the 9 holes of 73mm are not enough for these size of woofers if you want to use it only for a bracing panel.

In my case the two woofers will behave differently in this proven design.
It's more / less a restriction panel with fine-tuning possibilities.

As with the previous version of the Basis, the two woofers are each placed in a "separate" compartment.
The upper woofer behave as a bass reflex cabinet.
The volume of this is more increased because holes are made in the panel between the lower and upper compartment.
The woofer in the lower compartment therefore works partly in a bass reflex room, but still has more properties associated with a closed cabinet.
This results in a tighter bass reproduction for the lower woofer.
It is also possible to adjust the bass to your own listening room by placing more or less damping material over the holes.

The former design had a ’Briggs’ filter, the upper woofer had a separate volume (a lot smaller than the 95-version) With perforated back. I don’t recall that construction to be repeated in this version though. You could try and ask Rolph Smulders. But I see no problem in the build, as the woofers share the low pass branch. That was not the case in the former design, which probably was why the Briggs-construction was used in that one.
On your woofers, I thought the design used the carbon fiber reinforced cones that Vifa had for a short time (25CF300, as AudioComponents called them). I thought you had those too, IIRC.

 

[Hondasnl]

Hi Mark thanks for your reply.
This version is equipped with the M25WP woofers.
There are several variants I found on the web, also with the M25WPs.

My other plan is to put each M25WP in a separate cabinet, each about 105 liter.
Is that possible with the current XO?
I think it is no problem, only the bass will be deeper.

On the other hand, according the original design with 2x M25WP into 105 liters the curve is much nicer and completely flat.

 

[planet10]

from the look of that sim either the box is too big or the tuning too high. And certainly not flat.

I follow this rule when looking at any sim: the first derivative of the frequency response should only cross zero once. Yours oes so twice. You want to lose the shallow dip just before rolloff.

dave

 

[markbakk]

105 liter per 25WP is a bit overkill indeed. 60 should suffice. Long ago I glued weights on the paper equivalents of these, just to get them down to 25Hz In 60 liter. That was before I discovered B6 (Keele) tuning. 😛