I'm looking forward to seeing what you build - I love watching DIY projects.

What wood are you using?

The cutted edges will need some filling and then I'll paint everything but the front panel black.

I was thinking that Walnut would be nice. I have the rest of my equipment and also the television in a Cabinet made of some similar wood.

But we have plenty of birch growing here in Finland and birch veneer would probably be considered more local design....

Is that particle board going to be solid enough?

The shape looks nice, I like the start!

The reason for choosing particle board here were economical.
One sheet of MDF would not have been enough and this particular particle board came in a more manageable size (600 x 2000 x 22 mm).

I don not know if the particle board is solid enough. Do you think that it might break at the weak point where the tuning slot is?  

I understand that MDF is often preferred by speaker builders.
It is considered a "dead" material. I'm not experienced enough to
know what that actually means but I have thought that it would mean that it resonates at lower frequencies due to higher mass (density) than other available materials.
 The particleboard I use here has a density of 720 kg/m3 and MDF is according to wikipedia 600-800 kg/m3, so no difference there...
 And as I understand it the most effective way of reducing resonance of the cabinet is by adding bracing to shorten the resonating "springs" in the construction.
 This has led me to the conclusion that MDF is preferred mainly since less work is needed to get a nice finish of the cutted edges.

Birch plywood is ofcource nice and also more costly.

The front panels are taking shape.
They consist of the same 22 mm particle board and another less dense (ordinary IKEA quality ) 12 mm particle board glued together. They are veneered with oak veneer and then there is a 10 mm strip of oak around the edges.

From the front:


From the back:


And the hole from the front:


The hole from the back:


The edges:


Now some sanding and then I think I'll apply oil or wax to the surface.

It's taken awhile but they are starting to look right

Those look great! Good work!

The sound is great! The bass is much stronger than I expected.
They are passive now. In the end I didn't put the hypex in these. I just have an ordinary NAD amp driving the Seas elements. They are quite sensitive though so 25% all ready start to hurt my ears. I haven't done any measurements yet. Also I have the opening full open in the back. I need to find some good material to play when I start tuning.

I'll post a few pics

And then hid it behind the felt. Also You can see how I have fastened the front baffle to the cabinet

Kimppe wrote on 08/16/14 at 18:03:28:


I agree.

Nice looking speakers.

Wow, great job! Very impressive, especially the measurements.  It's excellent to see other peoples measurements and how they compare.   My measurements of the ZOB were done with the FRX drivers and the response you've gotten is amazingly similar.  It shows how much a cabinet actually effects the response of a given driver.

Here is the FRX response in the ZOB in our listening room.



What is probably more fascinating is comparing your response to the published response of the SEAS driver:



Your response is quite a bit better.



Congratulations on a job well done!

Kimppe said:
"Another thing is how "acoustic" the bass sounds."

I like that a lot!

Thank you for the posts on your project! I have been researching OB with a focus on Steve's of course and this is great material. You made some great looking speakers and I am glad they sound good and work in your room. Keep us posted and yes I think Steve's 2 watter will do great on your speakers.

Hello Tom,

you can see it on reply #19 and #21. I fastened (with glue and screw) a piece of the same particle board that the cabinet is made of back to the front baffle and then another bigger piece on top of it. This second piece will go inside the cabinet and "clamp" the front baffle to the cabinet.

Something like this:

http://www.berlins.fi/zob/zob_fb_fastening.JPG

The measurements above are in the right direction, not exact.

Best of luck with your buld!

regards, Kimppe

Correct!

In my case a thinner and less dense particle board (on the frontside of the front baffle) was glued to a thicker and denser one. As s result the front baffle bended just a little so I had to use force and bend it back with the two screws between the "ears". This means the cabinet is nice n' tight all the way from bottom to top.

If you manage to get the baffle to bend the other way you might need some other fastening method. ... Or just thicker felt

If you make the front baffle straight snd balanced I think it will be just fine with the cleat and the two screws.

Hi Klimppe. I know, it´s veeeery old history, but i hope for your answer. Because i´m here new, and have zero knowledge about open bafle speakers, i search for some infos. Because i also / like you /, after first looking ZOB speakers get love to them, i directly bout DIY plans and after found your job, threat, ordered SEAS FA22RCZ 8" drivers. I can´t send you a private message, i´m new member. My first simple qestions are - did you made some modifiaction on the boxes, for these drivers? (They are different, than recommended ones) Did you use some parts for made balanced sound from low frequencies to highst (as recommend SEAS for this driver)? Did you finaly use some "foam" inside box, for rezonator box? Is this driver fast and under control enaugh - clarity, bass, vibrations, magnet is strong enaugh,  etc...?  What do you think, is possible do/make something like Steve made - FRX modification on Fostex driver for ZOB? Made SEAS faster and smoother. And latest at this time - generaly - sound. Neutrality & neutrality, clarity, transparency, bass control & deepness, holographic sound-soundstage...?
 One more time, thanks for this asking. I know, is veeeeery old, maybe forgoten history, but i hope, you still can help me little bit. Thanks for time and patience and kind answer.  ;)