Golden ratio A8 cabinet plans

**martyh45** · May 10th, 2009, 10:38 PM

GM?s comments in the A8 thread got me to thinking about building a pair. I have never been a fan of the way they look so I drew this up while I was kicking the idea around and thought maybe someone else could use it.

I didn?t include a dimension for the woofer cutout as it will vary depending on which woofer you use and how you mount it but the placement should work with 16? frame units. I based the cutout locations on metal 32B horns w/ 802-8G drivers and 16? frame 416-8A face mounted. Obviously there are tradeoffs as the baffle isn?t quite as big but the resonances should be more evenly distributed and the scale is more residential than the original. Gross internal volume is exactly the same as the original. I?ve shown continuous corner braces and a shelf brace but I think everyone who builds cabinets has a favorite scheme. 1-1/2? 701 fiberglass on one of each type of panel should do for fill. (back, right side, and top)

Feel free to use the plan any way you like

http://laurenstephens.net/uploads/7bc9d81dbc.pdf

**Michael V** · May 11th, 2009, 01:04 PM

Thanks for posting that - the 32 horn is definitely worth experimenting with. I'm using the 32A (cast aluminum; the 32B is fiberglass) along with the 414Z and they really sound fantastic in the midrange. This horn is part of what makes the Western Electric 753 loudspeakers so sought after.

As GM mentioned, the HF balance needs to be dealt with. Without EQ or a supertweeter, it has a distinctly mellow sound. Not everyone's cup of tea...

**martyh45** · May 11th, 2009, 06:35 PM

Hi Mike,

Hope someone can use the plans.

I?m pretty sure the 32A horn differs from the B only in the driver mounting. The older WE small format drivers had three mounting bolts and the newer Altec versions have two. I don?t have them right in front of me but I believe my cast aluminum horns are marked 32B

At any rate, have you tried any of the Altec contour networks to flatten out the upper range with these horns? I think GM posted a few years back that hf dispersion is better with a 32 horn which leads me to believe that something on the order of a contour network designed for CD horns would be in order. My ears are older though so ultra high frequencies are not much of an issue for me.

**Michael V** · May 11th, 2009, 07:34 PM

It does seem Altec was "less than precise" in their catalogs and model specifications. My 32A has two mounting bolts for Altec 800 series drivers, just as the 32B. However, from what I understand 32B was fiberglass and actually had slightly larger external dimensions. I've also seen reference to a 32C (?). Who knows!

Subjectively these do seem to have great dispersion throughout the usable range. I haven't experimented with contouring... do you have any details of Altec's networks for the 32 horn?

Thanks

**Michael V** · May 11th, 2009, 07:41 PM

By the way, here are my speakers with the 32A...

michael v 184311 albums 32a 802 414 woofer loudspeakers 27 picture52 closeup showing metal 32a horn 414z woofer

michael v 184311 albums 32a 802 414 woofer loudspeakers 27 picture52 closeup showing metal 32a horn 414z woofer

michael v 184311 albums 32a 802 414 woofer loudspeakers 27 picture51 10 deep cabs apartment friendly thanks bent 32a horn

**mah** · May 11th, 2009, 08:46 PM

Tweeter for 32A.

Open link, then scroll down.

Your First Webpage

Lots of pictures of other interesting stuff.

**Audio_by_Goodwill** · May 11th, 2009, 09:07 PM

Originally Posted by Michael V

....... However, from what I understand 32B was fiberglass and actually had slightly larger external dimensions.......

I used to have a pair of the horns from 1221A Stage monitors. They were aluminum and the literature I found online called them 32B's, and also a part number.

I sort of wish I still had them. I did get a good price for them on Ebay, Though........ I shipped them to a US address, but they were ultimately headed to Japan.

It's nice to hear good things about them....... the last conversation I heard about them they were being run down.

**Audio_by_Goodwill** · May 11th, 2009, 09:10 PM

This certainly is interesting!!!

no33b

**martyh45** · May 11th, 2009, 09:59 PM

Mike,
The numbers of the add on networks escape me but the part we are talking about is a filter that suppresses the mids while leaving the hf run full bore. So, the filter has a rising response as the frequency rises to counteract the horn/drivers falling response. The only example I can think of in schematic form is the adjustable version used in Jeff Marquart?s 604 crossovers. The N1285-8B (and -8A I believe) had an adjustable version of this filter built in for use with CD horns.

Altec Lansing 604-8H Crossover Revelations

Cool tweets Mah, I probably couldn?t pay for them though. Thank goodness for fostex, some of their alnico super tweeters are pretty reasonably priced if I need them.

**Michael V** · May 12th, 2009, 12:04 AM

Mah - I've ran across those pics before, very interesting. Add-on tweeters were kinda mandatory when the mid-hi drivers like the 722 ran out of steam at 6k.

Marty-
I'm not familiar with the 1285 or really any of the original Altec crossovers, but I've seen one Altec design with a 2uf across a 10R series attenuating resistor. That helps equalize HF output as you describe, but I assumed that was just to fix the 806's weak highs.