Onken speaker cabinet, need a few build suggestions

[MrMonster]

Hello Lads,
I had posted before on Altec 515B cabinets, but since then I have changed directions. I came into a pristine pair of Altec 416B woofers, and have decided on building an Onken cabinet for them with my 288C drivers with the German Jabo conical horns sitting on top.

I am contracting with a cabinet maker to acquire the wood and do the cuts, as I do not have a table say that can do precision cuts as his big shop saws can do. He will also cut out the speaker hole and drill all the screw holes for me. I will end up with a "kit" that I can assemble in my garage.

I need to make final decisions on the build before wood hits saw.
He can get 13 ply Baltic Birch plywood in a high quality form. I can order 3/4" or one inch sheets, The problem is that one inch sheets adds $40.00 per sheet over the 3/4" That's $240.00 extra to the total cost.

So the question is, IS 3/4" adequate? or does one need to stick to the Hiagra 25mm sheet stock? is the 1/4" extra going to make that much more difference in the end?

Next is insulation. Following the Hiagra build, it appears he is using lambs wool felt only on the back and upper 3/4's of the sides of the baffles.
I see from Onken build sites on the web, that many new builds are using a full insulation with an additional back insulation of what appears to be audio grade foam sheet.

And lastly, does the Onken box box sound best flat on the floor, on a riser, or even casters? My house has wood floors with area rugs,

Any Onken builders or speaker experts in the crowd, I could use some input before I start writing checks.
Thank you,
Donald Bowman

[David Yost]

I would build it exactly to Hiraga's specs, otherwise, there will be a difference in sound -- and that includes using lamb's wool only. Amplification also matters here -- I think Hiraga used class A solid state, IIRC.

If you really want to go big, try an Onken W.

[SOOTSHE]

As far as the material thickness goes, I would recommend going with the extra thickness & also brace the cabinet well. Those 416's are going to give your cabinet one hell of a pounding & you'll regret it later on if you find you have resonances.
Any money you save by going 3/4" will be overtaken very quickly by trying to overcome a problem later on.
Just my 2c worth.

Good luck with the build....they should sound awesome.

[martyh45]

FYI,
The original article came out around the same time as the 416-8B and Hiraga tried the 416-8B and found it lacking in that cabinet. Also, the Onken was designed around a low Zout amps so solid state is in order. I have read that high Zout amps and 515?s can work in these boxes but I think it would be pretty tough for any of us to improve a Hiraga design. You might think about starting with an utraflex calculator and plugging in the TS parameters for your 8Bs

[Panomaniac]

I'm not an Onken expert - but I did stay at a Holiday Inn Express last night! (really)

Having heard those cabs many times, I can say they do well flat on the floor. At least on carpet. Don't remember all the amps I heard on them. Various stuff, from 300B SE to 300B P-P to Class-A solid state to Hafler. Hiraga likes solid sate on the bottom end, I know that for sure, on any big system. But he promoted the 300B tube as the best "all-rounder" for single amp use in a modest home system.

The 100% wool felt was something Mr. Hiraga said he found for hospital use to prevent bed sores. It was not cheap. But it was good. I used it in several projects. It's best to put a curtain 1/3 way back instead of the wall covering shown in the original article. If you can't get it, look into the new Bonded Logic cotton insulation. Also very good. The stuff with the foil is densest, and the foil peels off with a little work.

If you build it from 25mm plywood, you don't need extra bracing. The vents really stiffen the cabinet. Don't forget the brace from the back to the driver.

As fr the difference with the 416B, I don't remember. Long time ago!

You won't regret building this. It's a hell of a bass cabinet. Not sure why it has the magic it does, but it does have magic.

[MrMonster]

Hello Lads,
Thanks for the information.
I was able to get a reply from Manuel that did the photo build site at Ispra.Net - Alex Patak Audio

He reports that his build was from 25MM "phenolic Beech" plywood, and the insulation was 10MM unbleached wool felt. the best results were from directly on a heavily carpeted floor.

I guess I will go the purist route on this, just need to find the extra dough to commit to this project.

The only thing I can find no definitive answer to is the Altec 416A or 416B choice, While Hiagra wrote that "he did not care for the sound of the B, there was no other reflection as to why.
I have not found anyone so far with experience with both the woofers to expound on it.

But, for now, I have a near new pair of 416B woofers,, in the future I could indeed try the A, as it would not be too hard to swap woofers, at most just making a new front board.

Anyone out there with both versions of the 416 that can comment?

As for amps, I own a Pioneer Spec 2, and Spec 4, a pioneer Sa 9100 and a Sa 9800, plus a number of 70's receivers.
I will be looking for a tube amp soon, just not sure what to look at that is within a reasonable price.
Thank you all.
Donald Bowman

[MrMonster]

Hello Lads,
Last thoughts on my Onken project before we start cutting wood.
Here on the West coast, Baltic Birch is almost impossible to find, and when available in one inch thickness, is only in 5x5 sheets which would require an additional 3 sheets to make the cabinets.
My cabinet maker showed me a sample of a Maple Apple no void plywood in one inch that is 17 ply.
We cut up a 1 by 2 foot sample into 2 inch squares and could find no voids.

So is this a good choice of wood since the birch would add $500.00 to the build that is already nuts.

Also, since I am using the 416 B woofers, do I need to enlarge my speaker opening from the original 34 CM? for the 416A
Thanks,
Donald Bowman

[Panomaniac]

I don't think you need to go over 340mm. My A7 cabs were built for the old 15" frame drivers, but have the newer 16" in them now. No problem with fit, as far as I can see.

But I'll go measure a pair in a bit and let you know. IIRC, Mr. Hiraga liked to cover some of the surround anyway.

[bowtie427ss]

Maple Apple no void plywood in one inch

called "apple ply" here, excellent stuff!

[Altec Best]

Hey Don, I talked to you over at LH about which woofers to use.416-8B :2thumbsup: Well anyway here in NJ the 1" ply comes in 4x8 sheets and the 3/4" comes in 5x5 sheets the 3/4 Baltic Birch(BB) is $38 a sheet and the 1" 4x8 is around $180 a sheet it is very expensive.So just be very careful before you make your cuts at those prices you would like to keep the scrap pile to a minimum.It's nice to see you getting started Cool ! Please post pics of the onken.I always liked the look of the onken W with dual 416's And contemplated building one before my current project but going with a corner box instead.So I would like to see it for sure.