Altec 9844-8B

[MrT]

Hey Skywave

Thanks for the graphs. And thanks for measuring one 414 a side. You did not forget me. Awesome!

I am using 3.7mh+10uf+zobel (16ohm+10uf). I am using a set of selector to use the crossover and the first order, the second order, and the first order with zobel, and the second order with zobel. Each has it's merit, I think.

Zilch. I have not forgotten about the active crossover yet. At this point I am wrestling with my home brewed preamp hum. It seems like my system is full of problems.

By the way. With the helper zobel is not really needed. Right?

Thanks guys.

Timp

[Zilch]

By the way. With the helper zobel is not really needed. Right?

Unknown.

Zobel's action's not down where the helper is playing, rather, up in the main lowpass region.

We're not working there yet....

[Zilch]

The video has enjoyed 105 views, and nobody has said "Boo."

Multiple choice:

1) Too esoteric; nobody gets it.

2) It's really, really dumb.

3) "You speaker geeks are WAY too easily amused...."

[Chas]

The video has enjoyed 105 views, and nobody has said "Boo."

More like: Very familiar to me, as I have spent a few Sunday afternoons seeing and hearing that......

[Skywave-Rider]

To me, a combination of all 3. LOL.
Chas, good to know we're all in the same asylum.

[Zilch]

More like: Very familiar to me, as I have spent a few Sunday afternoons seeing and hearing that......

We're not letting you slip away that easily, Chas.

Is this going to work for Skywave's 9844s? Tell us more about your experience doing "Helpers," please....

[Skywave-Rider]

We're not letting you slip away that easily, Chas.

I'd love to hear about your experience, Chas.

[Zilch]

Member Bfish over on the Altec Forum observes that, while entertaining, the video is unfair to the single woofer playing alone at the beginning in that the second, unconnected one, is functioning as a passive radiator and altering the box tuning characteristics. Even if the voice coil were shorted out, the tuning is still for two woofers, not one, and inherently wrong. What we're seeing there is multiple variables converging favorably to produce the effect.

Though the video was produced primarily for giggles, that's a valid criticism which suggests an alternative experimental design with the potential to yield additional useful information: Start with the inductor shorted, i.e., both woofers playing concurrently, then unshort it to observe the attenuation outside the region where the "helper" makes its contribution.

Do the dual woofers normally mutually couple at those higher frequencies? How much SPL are we actually "giving up" to achieve the extended bass produced by this scheme? Do we care even one whit about losing that in exchange for the apparent bass extension benefit? :dont-know

[Skywave-Rider]

OK cool!

Question: Does it follow then that if one was to redesign a speaker like this that it would be a matter of course to look at partitioning the box unequally into 2 volumes tuned for each woofer and their respective ranges? (That is if one did not care about efficiency from 2 414s working in tandem in the same volume.) And don't speakers couple anyway, even in separate enclosures?

I gotta read all the box stuff in Dickason.

I'll plan to run those tests.
Edit: I just read your post again and now more fully understand what you said about the higher frequencies the woofers are producing together and how we must determine the attenuation when switching to 2.5 mode. Thanks!

[Chas]

I'd love to hear about your experience, Chas.

Sorry, my time with Altec stuff ended in misery, so I gave it up years ago for JBL.....But, I do still kinda like the stuff.

I didn't try what you're doing, but I think it makes good sense. This thread is a keeper, for sure.

In fact, I am planning to make a switchable (parallel or helper) four 2235H (two per side) same concept similar to the 4435 except with four modular, independent boxes.

Now that I think about it, the 4435 shared woofer volume in the early versions according to a few folks here, but not for long. They apparently added a partition later.

Good luck guys, I'll be following closely.

[Skywave-Rider]

Sorry, my time with Altec stuff ended in misery, so I gave it up years ago for JBL.....But, I do still kinda like the stuff.

Hahaha. Yeah. I'm goin' down, I know it now for sure. But flailing all the way.

I appreciate hearing about your experience. I'm learning a lot and could not have done any of it without Zilch and all the others down through to the bottom of this thread and elsewhere. I'm pretty sure I have the stamina to roll with it.

I know little about JBL. Though I'm learning and respecting.

My experience with JBL is as control monitors and I never liked them in that application. However, any working speaker takes time to get used to. I won't argue with anybody's preference.

Yeah, I could easily lust after 4435s.

[Zilch]

Question: Does it follow then that if one was to redesign a speaker like this that it would be a matter of course to look at partitioning the box unequally into 2 volumes tuned for each woofer and their respective ranges? (That is if one did not care about efficiency from 2 414s working in tandem in the same volume.) And don't speakers couple anyway, even in separate enclosures?

As Chas observes, 4435 may have been made both ways, but everything else that comes to mind is common chamber I believe: 4612, SK2-1000, Everest II, dual-woof 43xx (?), even the early horns (?), Westlake et. al (?). Mr. Widget or others may have done some experimentation relating to Project May.

In the helper schemes, it seems to me not to matter, at least with respect to the fundamental tuning: you tune for the dual woofs, because they are both playing in the region where box tuning has its primary effect. Outside there, I'm not sure but that isolation has some benefits; they're just unknown to me. Manufacturing costs may also play a role here, as well, when we look to actual product for design guidance, though the flagship statement Everest II could clearly have been made either way.... :dont-know

[Chas]

In the helper schemes, it seems to me not to matter, at least with respect to the fundamental tuning: you tune for the dual woofs, because they are both playing in the region where box tuning has its primary effect. Outside there, I'm not sure but that isolation has some benefits; they're just unknown to me. Manufacturing costs may also play a role here, as well, when we look to actual product for design guidance.... :dont-know

Makes sense to me too.

[MrT]

414 happens to be my favorite woofer. It will be a wonderful to see them being maximized. I am so excited to see you guys doing this. On a side note. There were a guy in town selling 4 9844 driven by 414-16Y for 500. I missed them by a phone call. I wish I could have bought them. So I could be part of the project.

As I get a chance I will post some pictures.

Timp

[Skywave-Rider]

On a side note. There were a guy in town selling 4 9844 driven by 414-16Y for 500.

A much better price than I paid. Yeah, it would be great to have 5 of these in a surround setup, but I can't really even fit my Heresies in my apt. as it stands. Frankly, I feel lucky to have a decent pair of 9844s and a place to keep them, as inconvenient as that place may be.

Hope to do the next round sometime this weekend.