DIY speakers using 32-liter cabinets

[smurfette]

I have two unused 32-liter enclosure kits that are originally meant for subwoofers. I intend to build two-way (or three-way) vented-box loudspeakers using these enclosures. Thiele-Small parameters are just right for my enclosures if I choose 8'' Visaton WSP 21 S woofers which have a fairly low resonance frequency of 28 Hz and VAS=80 liters and QTS=0,28.
But what kind of tweeters and crossovers should I put in? If I use a tweeter with a low resonance frequency and a first-order textbook Butterworth crossover, do I have a chance of success without measuring equipment? Or is someone aware of a two-way or three-way design using approximately 32-liter enclosures that I could copy?

[sreten]

You should copy an available design for 30 to 35 litre cabinets.

Only possible issue is baffle width being different, you can tweak
the inductor value in this design :

http://www.seas.no/kit/Njord.pdf

The crossover is not as simple as it appears......... well it is but....
(I mean it cannot be easily designed on paper)

sreten.

[smurfette]

I think I have had a look at this Seas Njord design some time ago. It is designed for 40 liters and I have only 32-liter cabinets. According to Thiele-Small equations, my cabinets are somewhat too small for this design.
My baffle width is 340 mm, I think it is wider than the baffle width used in the Njord design. If I chose the Njord, which way should I tweak the inductor value?

[sreten]

Yes you are right - I thought it was around 35 litres.

Not to worry its all a questoin of bass alignments, but I did
notice the impedance curve is for a sealed box not a reflex.

The inductor should be a little higher in value for a wider baffle,
though if you offset the drivers horizontally it will make less
difference, i.e. if you move the bass unit near one edge I
wouldn't worry about it too much.

But if I was winding the inductor myself I'd add taps for tweaking.

Note that with damping included reflex box volume is ~ +10%.

sreten.

[sreten]

many designs can be adjusted to your box -
heres the KLS9 with a more sensible alignment.

Most of the previous coments apply, the drivers
are somewhat more modern thsn the Njord.

sreten.

[phibes]

I've built several KLS9 loudspeakers and always worked on a box volume of 2.6 cub ft or around 70-75 litres. Have you heard the KLS9's in a 35 lt enclosure? If so, did you alter the xover at all?
Cheers,
Keith

[sreten]

Originally posted by phibes
I've built several KLS9 loudspeakers and always worked on a box volume of 2.6 cub ft or around 70-75 litres. Have you heard the KLS9's in a 35 lt enclosure? If so, did you alter the xover at all?
Cheers,
Keith

I'm not saying the KLS9 shouldn't use a 70 litre box simply that
for those concerned with space, or those who already have a
box it can easily be used in other boxes.

If the baffle layout is similar no changes to the crossover are
required. If the baffle is wider, offsetting and perhaps inductor
tweaking would be required.

I've haven't heard a KLS9, nevermind a 35L version.
But like the Njord its a simple design, easily tweaked.

As the original design article says, 75L is really the biggest box
you could put it in, any larger would be pointless. Bass vs space
wise the driver indicates 40 to 50 litres would be the more normal
compromise.

Oops... I clicked on the driver next to it for the above curves,
here are some for the correct Audax driver :

sreten.

[smurfette]

If I choose the SEAS Njord design, could a 3.3 mH inductor instead of 2.4 mH one be just appropriate for a wider baffle? I don't want to wind the inductor myself.
How much space should I reserve between the end of the reflex tube and rear wall - is about 20 mm enough? (I have already a 90 mm hole in the baffle and want to use 90 mm reflex tube, so it has to be about 30 cm long and the depth of my cabinets is 34 cm).
Why cannot I design my own first order crossover on paper if I use the at-crossover-frequency-measured driver impedances in the Butterworth equations? If I feel lucky?
BTW, the Audax woofer used in the KLS9 design seems to be discontinued, at least I didn't find it at www.audax.fr.

[phibes]

Hi,
I've built this design three times over the past few years with the original for eldest daughter being closer to 59-60 litres, rather than Keywood's 70-75 litres. Although the second two KLS 9s sounded ok, I always preferred the characteristics of the original. Bass response is a little tighter and defined in my daughters pair of KLS9's. I might try them in a 40 - 50 litre enclosure. Thanks for the graphs.
Cheers,
Keith

[phibes]

Hi Smurfette,
The first pair of KLS9s I built used the HM210Z0 bass driver. That was subsequently discontinued, however, replaced with what they said was an improved, enhanced bass in their new model, the HM210Z12.
Perhaps Sreten can run you a graph optimizing that driver. I didn't notice a lot of difference between the old and new drivers!
Cheers,
Keith