Altec Lansing

[Geoff H]

Hi Cal, what I was thinking with your stacked horns, was to try shelving the the lower horn at 1200, rather than rolling it off.

Seems a shame to have that horn only covering a bit over an octave.

See the rough sketch attached.

And what is this "Bench Racing"? Sounds intriging.

Grasshopper, I found with my 411s, off the shelf inductors were "sad"
The 2.5mH ones I bought muddied up the sound. Found they had 1.5 ohms as well. I hand wound a pair of 2.6mH using 16 AWG. Huge difference. Only 6db/oct. The high side was a bank of 20 x 2 uf AEE al foil - not much sereis inductance in that.

Cheers,

Geoff

[panomaniac]

Originally posted by Zen Mod
Hiraga's xover,one page from SP article

Thanks for posting that. I suppose it's for the A7-500?
Alas a lot of the values are hard to read (common problem with 1 bit gifs).

I can personaly attest to the fact that Mr. Hiraga builds a great sounding crossover. Though I haven't heard this one, IIRC.

[Zen Mod]

Originally posted by panomaniac


Thanks for posting that. I suppose it's for the A7-500?
Alas a lot of the values are hard to read (common problem with 1 bit gifs).

I can personaly attest to the fact that Mr. Hiraga builds a great sounding crossover. Though I haven't heard this one, IIRC.

I posted that from really old scan;
if someone is interested,I can scan it tomorrow again......or .....I'll put whole article on my temp web

[Cal Weldon]

Originally posted by Geoff H
Hi Cal, what I was thinking with your stacked horns, was to try shelving the the lower horn at 1200, rather than rolling it off.

Hi Geoff,
Right now I have just fooled around with fixed L-pads but I hear something a bit strong and I think it's around 1-3K so I'll experiment with some notches and see if I can tame it a bit.

Isn't a shelving network just another name for a fixed (non-variable) L-pad where you have incoporated the frequency of shelving independent of the XO? If so, that's not quite what I wish. I just wish to rework the padding so I am able to get more off each end of the midrange and cut back the middle a bit.

[i]Seems a shame to have that horn only covering a bit over an octave. [/B]

600 - 5K is what it covers

[i]See the rough sketch attached. [/B]

Thank you.

[i]And what is this "Bench Racing"? Sounds intriging. [/B]

What we used to call "race car sets" Another member is heavily into it and our beloved GM has been involved in the past. He can correct me if that's wrong.

[panomaniac]

Originally posted by Zen Mod
if someone is interested,I can scan it tomorrow again

Yeah, I'd love to see it - thanks!

[Geoff H]

Shelving, as I understand it, ie on the Barcelonas (Altec network #30904) attenuates the lower end of the horn, without as much, if any, on the top end. Just flattens out the response. On the 411 based systems, there is a big difference in sensitivity, 8 or 9 dB from memory.

FWIW, when I have played with that sort of thing, found it easier to disconnect the top end, run the "mid" on high pass only. Once that's sorted, work on the top end.

Wouldn't life be easier with 2-20 uf variable caps?

Don't take the values on that drawing as gospell. They're calculated on 8 ohms resistive.

Bench racing sounds like what we call slot cars. Most of the thrills, no bruises or panel shop expenses. You big kids! When's the next meet?

Geoff

[Cal Weldon]

Hi Geoff,

I think we understand shelving to be the same thing.

Slots cars is another name yes.

I can't help you, I'm not involved with them. RacerXtreme is your guy. He has or had a very large set up. In fact he used his A4's as part of the platform.

[carawu]

Moin,

here it is.



LG Carsten

[GM]

Originally posted by Cal Weldon
Hi Geoff, the XO's are approx 650 and 5K, 12 dB

The lower is a Selenium D250-X on the 511 horn and a Selenium D205Ti on the 811. The woofer is a Selenium WPU-1507-QCF.

Greets!

Ah, OK, my comments assumed combining them over a wide BW to take advantage of the smoother, more robust response of the larger combined mouths. FWIW, using an 811 as a tweeter will in theory sound more cohesive with it positioned between the 511 and woofer, but never having heard the combo either way AFAIK............. with your nifty tie bkt. it shouldn't be hard to try though.

Interesting about the Seleniums, seems to me these were discussed awhile back on the HE forum and the consensus was that they wouldn't mate well enough with the 511/811 to make extended, high SQ HF.

GM

[GM]

Originally posted by Cal Weldon
GM,

A matter of respect. I'll call you G from now on.

With that aside, this has been a fun little project. I like this kind of thing.

Greets!

OK, thanks for that. FWIW, I'm so used to 'GM', both written and spoken, that anything else in a casual environment seems kind of strange.

Anyway, understood, you're apparently as easily amused as I am and good to know it works well enough.

GM