Markaudio Alpair Hybrid

[Spassgeneral]

Hi Guys,
long time no see.

It is time to do something new.
I have two pairs of alpair 10.3m lie around.
I looked at all the recommended enclosures and think the FHxl would be fine.
but the footprint of these is to large. I would like something in my favourite
100 x 25 x30 cm.
I also would like to do some dual driver as I already have them on hand.

A larger micro tower would be fine or a double MarKen wich I have seen already, but I did not find any plans for both of them.

So I'd like to develop something by my own.
playing around with hornresp I came to following approach.

It's kind of transmission line loading into a horn.

What do you think?
Is this a way to go?

thanks in advance

Der Spassgeneral

 

[Spassgeneral]

150 views and not a single opinion?

come on ...

 

[chris661]

Looks like it'll work fine to me, so long as the narrow port doesn't suffer at high power levels.

FWIW, I'd aim for a response that slopes downwards into the bass unless you're using the speakers outdoors.

Chris

 

[Spassgeneral]

Hi Chris,
You are right. I also thought about the narrow gap.
But it is almost 40% of the total SD of both speakers. So it should be sufficient.
I can play around with hornresp to optimize this.
Have to see how widening does effect the response.

 

[planet10]

A larger micro tower would be fine or a double MarKen wich I have seen already, but I did not find any plans for both of them.

There is no larger microTower (but it is certainly doable), most of the Mzr-Kens are in paid plansets.

For 2 drivers take a single driver enclosure and “double” it.

dave

 

[planet10]

But it is almost 40% of the total SD of both speakers.

The Sd has nothing to do with it.

dave

 

[Spassgeneral]

I thougt member COGITECH build a pair of micro tower based on alpair 10.
But may be it was only his intention.

 

[Spassgeneral]

If the opening to the horn is not dependant on sd. What else ? I assumed it depends on the amount of air that has to move through.

 

[Spassgeneral]

Hornresp max SPL looks fine, too.

 

[planet10]

If the opening to the horn is not dependant on sd. What else ?

Vas, Qt, how low the box is tuned, the volume of the box, the driver’s volume displacement will put a limit on how low or loud they can go.

There are no real easy answers, these really need to be modeled.

dave

 

[Spassgeneral]

May be someone could verify my design with another program like akabak or ajhorn.
I can't see any flaws but I am not so experienced.

 

[Spassgeneral]

Not so many opinions.
But at least no bad ones.
So I bougt 21mm birch ply and started.

 

[Spassgeneral]

Ready for the first test run.
Still waiting for the felt to line the walls.
Some bracing is also missing.

 

[Spassgeneral]

Very promising results.
Definitively does not need baffle step correction.

Quick uncalibrated measure just to get an idea if everything is going into the right direction.
Taken at listening position at 3m distance

 

[Spassgeneral]

Without any correction solid down to 40hz.
I am curious to see the results when the side of the eclosure is glued and the box is properly sealed.

 

[chris661]

Any chance you can set for a log scale? Linear scale doesn't represent audio too well.

Chris

 

[Spassgeneral]

You are right chris.
But to see if there is something totall wrong it was sufficiant for me.
The log graph gives basically the same results.
Green line starting at 37hz.

The alpairs are wired in parallel.
Amplifier is a magnat tube rv2

 

[Spassgeneral]

So,
during long listening sessios I adjusted the damping. As always., less is more.
Everything glued together.
I oiled the birch ply with linseed oil.
The oil is in dark walnut colour. Looks quite good.
With the dual binding posts I can run the drivers in parallel or in series.
Binding post panel is sealed with self adhesive foam.
Last thing missing is the removable clothed front grill.

 

[Spassgeneral]

It's not easy to show the finish on the fotos.
Looks much better in real.

 

[freddi]

your design looks like a super project - with decent bracing do you think 12mm Baltic birch plywood would sujffice ? Is the ~4K dip a result of the driver's center to center spacing? - or something elese ?