Altec Model 34

[Zene]

Hi ... Can I ASSume that I can flatten the back from a Model 34 that I would like to build, as long as the volume is correct? Old Man said were good. They must be. Any other comments worth repeating? http://www.lansingheritage.org/image.../c34/page2.jpg
page2.jpg. Zene

[Old Guy]

Hi actually that's a JBL box. I don't see any reason why you couldn't extend the corners. You'd need aa angled panel on each side inside in order to keep the inside dimensions of the box the same I fill all voids. I use foam, I've heard of everything from Kitty litter to concrete.

The 34 isn't a perfect box- the lower bass is somewhat out of phase due to the long path. But it's that same long path that's responsible for the lower bass being there. It's one of the few ways to get such a long horn into a(relatively) small box. The Imperial of course will have the same problems, being a similar concept.

I read somewhere, Engineering is often a compromise solution. The successful engineer is the one who makes the best compromises.

[Zene]

Hi ..Thought you'd come to my rescue again.
I stand corrected, been lumping all Lansing/Altec boxes together. If the JBL 34 is still not ideal for bass and a bigger box is certainly indicated for my purposes, what would be a closer to ideal solution(s)? Room size will be about the same here or elsewhere (12x33x7-10 vaulted ceiling and extended openings (around 4000 cu. ft.) I just may have to bite the bullet and do one more biggie. There is no WAF for us bachelors (me and son). I get the whole room/kitchen. I do have corners available on the 12' wall, but as you see below the other speakers would all not go into a corner. Might a big box indicate a close to Onken style (big ports)box or a standard ported rather than a horn for optimum results? The clone 2226 goes in around 6 cu ft at best, but two 2226's per side and 12 cu ft each? My upper bass and higher will be anything from my 12" coax (OB or horn loaded), 811 style horn/tweeter, or 6 1/2" x 12 OB curved array and beyond. All very high efficiency. Bass will stay the same and I just change the rest as a listening laboratory. The Behringer should help bail me out of most major conflicts. Zene

[Old Guy]

Hi again.
I didn't mean to imply that the 34 is a bad cabinet, and there is an ideal out there somewhere.
Just meant that we don't live in a perfect world. We live in imperfect rooms,listening to imperfect speakers fed by inperfect sound sources that feed our imperfect ears which translate information for our imperfect brains. Why , it's wonder the darn stuff works at all!
The best compromise is what best fits your musical taste in your room. All else means nothing.

So you are the engineer. You need to learn all you can, build units and try them, all in the eternal struggle for that last few percent. It'll never end. Once you catch the bug it's a life sentence.
I'm predjudiced in favor of horns. I like the dynamics. I only point out the shortcomings so you are aware of them. Who knows- you might be the one who finds a way around those drawbacks.

But there are positives and negatives to all approaches. It's best to know both.

Sorry for being so long winded, it gets worse the older I get.

[Zene]

Guess what I need to ask is your preferences for horns of any size or configuration and why, as you have heard many more than me? Very difficult to build many of the more complex designs just for a listen. I, too like horns so would be my first choice. Always liked the dynamics and would trade that for very deep bass anyday. Easy for me to experiment with ported as they are very simple to design and build, but not horns. Please bill me for the great consulting. Zene

[Zene]

Good response for all to read. My problem is that my mid is 12" P.audio coax and goes pretty low, Fs is 42hz. Crossing it over too high encroaches on the coax tweeter. Somewhat different situation than yours. Looks like a ported box might be better suited.
Keep us posted as you work on the JBL 34, if you can. Problems along the way makes good background for any project. We'll learn on the back of your hard work. If it works well for you, I might try one with the P.audio 15 coax. ASSume you would want to build 4 and send me two for my birthday coming up in July? I like Black Walnut. Not for free of course, I will pay shipping and finish them. tee hee Again, thanks much ... Zene

[Zene]

Thought I was ready to go, then re-read your last post. You said, "The front is not horn loaded, so it won't interfere with the 604's hf horn." Would that apply to mid horns with coax drivers as well? And is it frequency dependent? Plans were for a large 150hz 4-sided conical horns for my 12" coaxes. Zene

[tgroendahl]

Dear Old Guy!

With a great interest, I have been following this thread.

At the moment I use quite large 4.6 x 2 x 1.6 feet 40Hz backloaded horns designed by the late danish speaker designer Duelund in the 70?s. The horndesign reminds a bit of the C34 but is longer I guess. The original drawings can be seen here: http://www.muyiovatki.dk/duelund/duelund.htm The horns has the bendings founded in concrete. A quite optimum solution I suppose, for the passage of the soundwaves.

I have my very sweet playing vintage 12" Philips 2278 drivers http://homepage.mac.com/tgroendahl/PhotoAlbum1.html mounted in them at the moment. On top of the horn I have placed my new 605B units, only using the hf-horn for the time being. The Duplexes can?t fit in the loadchamber of the Duelund horn without a redesign/rebuild, so I?d rather prefer to start a new project for the Duplex.

Another important thing is that I don?t thing I can live with the fact that the bass response from the horn is delayed because of the length of the horn.

I was always hooked on the look of the Altec frontloaded enclosures like the old A6 and the later A7 types. But I could probably only fit a set of 825/828 horns in my not so large musicroom.

In the Tannoy compound horn design http://tannoy.com/WestminsterRoyal we see a short quite open frontloaded horn in combination with a long backloaded tuned to a low 35Hz. But I have however never heard this huge speaker.

I was wondering if the frontloaded horn somehow would add sonic quality to the low midrange / midbass of the Duplex? Or is it evident that a Duplex driver (in my case the 605B) will never get to function optimum that way (in the A7 for instance), and I should just forget all about it...?
I wouldn?t mind to work on tweaking for a while if needed..

I have only on one occasion heard the A7, could you kindly describe your experiences with the low bass rendering of it?s reflex system?

Sincerely,
Thomas


My system consist of an EMT 930 turntable with DL103 cartridge. A complete rebuild Audio Note Meishu integrated amp, the riaa changed to an old RCA design, with cascode coubled Telefunken ECC801S in the first stage, GE 5687 (5 star) in the second, leading to E810F, that drives the 2A3 in SE operation. All transfer caps and riaa eq caps, are of the latest PIO phenolic paper encased type from Jensen (here in Denmark). Also the 5uF used in the simple x-over is of this very well sounding type. The sound of the system is very pure and open, with great transients and fine three dimensionality. I mainly listen to acoustical jazz and classical music on vinyl.

[Old Guy]

Hi guys. In order of posting, Zene, I'll have to give what is my opinion only- I don't think you will have a problem. Altec used the Duplex in a front loading horn , as was mentioned in the A6 thread.
In a large conical horn I don't see a problem. Where I would see a problem is if you tried to put a coax with a wide dispersion horn into a tighter (dispersion) bass horn.
Say you put a 100 degree HF horn in the center of a 60 degree LF horn. There may be reflections from the sides of the LF horn due to the mids hitting them. I think in Altec's case both the LF horn and the HF horn of the Duplex are both 90 degrees.

For Thomas- most of my experience with the A7 has been in using them for soumd reinforcement. In live situatuins we often boarded up the ports for better woofer control.
However there have been lots of posts to the group already by those more experienced than I. What I would suggest is first searching the posts here , probably good keywords would be A7 or A7 bass.

Then any questions you have strt a new post with A7 bass response in the header. There are lots of folks here who would be glad to help out.

Sorry if it feels like I'm dodging the question-I just don't have that info.

[selmerdave]

Old Guy,

"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."

How do you plan to deal with the issue of the depth of the compression chamber? That seems to be a problem in my mind, older duplex's are 11" deep and most RLH designs (including Imperial and 34) do no allow more than a few inches between the baffle and back of the compression chamber. I don't know about this stuff, though, perhaps this is easily dealt with which is why I ask. Or perhaps you are using a ceramic-magnet 604 which would not seem to have this problem. Thanks.

Dave