Altec Model 34

[Old Guy]

The problem with pure horns is, for bass at least, they have to be huge. I think minimum for a bass horn is around a 7 foot path that will load you down to about 40 hz. (1120 feet per second speed of sound divided by 40 equals 28 foot wave, one quarter wavelength is 7) Thats why you see a number of combination enclosures. Altec chose to use reflex loading for lows and switch to horn loading at the lowest opportunity, around 80 in the 210 and 160 or so I think in the A7. They dominated the market.

To make nclosures even smaller they didn't horn lad till 500 hz. These of course are the single 15' reflex and hornboxes.

My reason for choosing the 34 for my next project is that I want to use my duplexes. The front is not horn loaded, so it won't interfere with the 604's hf horn. The path on the rear wave is clost to 7 feet. So I think they'll turn out well.

For subwoofer use only, you can load the front of the bass driver. However if you try to get upper bass and mids out of a folded type horn, you'll get cancellations as the wavelength gets shorter and shorter. So a folded horn on the front of my 604's would totally wreck the mids and highs. The bass portion of a Klipschhorn for instance.

The Imperial, either design, would also allow the use of the Duplex. The folds look smoother in the 34 than in the Imperial, at least to me.

As far as how much time you need it's not a problem. I'm semi-retired so have a decent amount of time. If I'm not on the PC my GF will find stuff for me to do, so I spend a lot of time on the net.

If you need more info let me know, and as always there's a good bunch of folks here who will chime in.

[Old Guy]

There's a note on the print, apparently JBL had a similar problem with one of their horns. They chopped a hole in the bach panel making it a precision fit to the outside of the horn driver.. Hoping he sme concept will work with the duplexes, may need some sort of gasket.

[Zene]

OG ... Do you mind me being informal?
What do you think a realistic low frequency would be for the JBL 34 with a 2226; in my case the P.audio 2226 clone? I only need to get to 200hz at best so am more concerned with the low. Certainly cannot suppliment it with a subwoofer. Dumb! "Vacillating" is my first name. Reason for asking is if 2 are working on same horn, I might join in. And with help I may get one right. I can bring a little to the table for my share. 'Bout 32 years of sawing, gluing, cursing, etc.
Dave ... Glad you might join small crowd. Looking forward (if I decide to build)to working out the numerous details that come up. Like how in **** to do the curve properly?
VOG Zene

[Zene]

Guys ... I've got more problems than just mental.
http://www.lansingheritage.org/image.../c34/page2.jpg
Does anyone have the top dimensions for the 34? Tried everything to read and do not want to guess.
Zene

[Old Guy]

Hi Zene- I'm not sure what you need- the top dimensions are shown in the print. Can you expand a bit for an old guy with limited comprehension?

Per the drawing the top is 22 7/16 deep x 23 3/4" wide The angle cut starts on the side at 15 7/8" and the finished dimension on the back is 10 1/8. At least to my eyes. Or am I completely misunderstanding the question. Wouldn't be the first time I've been baffled.

[Old Guy]

Hi Zene. Aother box to look at- JBL made something very similar- this is probably easier to build. Both cabs should be good down to 40 hz. I don't have prints for the original JBL box- if anybody has JBL pro prints I'd love to have them for my reference library.

http://www.dancetech.com/aa_dt_new/pa/15-scoop.cfm

[Zene]

Old Guy, thx. "Baffled", very punny. Dimension problem was my old monitor and old printer,old eyes and a few other old parts. Curious why they didn't make it with 45 deg corners?
Are you into planning stages? If so would like to know if you intend to try to improve the turn corners and additional bracing? The bottom scoop could be flattened to 2 or 3 pieces, but not sure how much to screw with original design?
Years ago I read someone made a copy of one of PKW's speakers by using 3/4 ply instead of the original 5/8 and sounded like **** . Better is not always better. Zene

[Old Guy]

Hi Zene . Just at the very prliminary stages right now. I do a lot of outdoor shows (sound reinforcement), am pulling out gear that's been sitting all winter and shaking out the mothballs. I am heading into a busy period that essentially dies at the beginning of August do to the large state fair here- not much is scheduled locally to compete with it and the older I get the less I want to travel.

Hope to get all the plans worked out and actually get them built in that 3 week hole I will have then.

[Zene]

Mr. Old Guy ....
Good that you are busy. Me too, Yawn!
I will just wail on mine and wait for you to tell me where I screwed up later.
Will have a couple questions from time to time if you don't mind? One, if I calculate the volume of the corner pieces and shorten the depth accordingly, do you see any problems? The only one I noticed that it would change the scoop slightly.
Dave ... Would like to hear from you on your progress no matter how small and trivial the problems. These are not easy to build right, no matter how much experience one has. Especially me. Zene

[selmerdave]

Zene, perhaps you misunderstood. I was quoting Old Guy in my prior post. I would certainly like to build a nice set of cabinets (particularly Imperials) for my 604's as they are now in less-than-ideal boxes (Bozak 302a's), but it is not really possible to do that in a Brooklyn apartment and I don't have the funds to hire someone else to do it. It is always on my mind, though, and I'd like to have it figured out for the time that the opportunity does present itself so I can take advantage of it.

Dave