More questions

[nikki1]

I have some more questions. I know some of you may find them silly and irritating but for one like me who is not up to speed on this stuff answers are very helpful.

If I'm going to do this cabinet build I ought to do it right and so I come here hoping for answers from those who know waaaay more than I.

1- Altec specifies a sealed enclosure ( like a 9846) for my 411's. They also specify a volume of 4-8^3 ft with 5 being optimum. 5 is pretty small and will make it difficult to build a horn box which will sit on top and have the same dimensions. Any comments?




2- I have read that mounting the speakers close together in the vertical plane will result in better overall sound. Or can they be too close?




3- There is a discussion on the Altec site about placement of the horn above the woofer. Align the voice coils, align the mounting flanges or align the outer radius of the horn with the woofer. What's the deal there?




4- Apparently when wiring the woofer and horn the polarity on the horn is reversed as it's diapragm moves opposite the woofer and it should be done this way to properly phase them. True?




5- when setting the x over point can that be done with a meter on the output terminals of the x over box? Reading hz or voltage? If voltage what is it for 500 hz?




6- I don't know what the hf drivers are as there's no part or id #. The #7779 is ink stamped on the end and the #301339 is stamped on the OD of the driver. Anyone know which they are?



Thanks,


Lee

[bowtie427ss]

1- Altec specifies a sealed enclosure ( like a 9846) for my 411's. They also specify a volume of 4-8^3 ft with 5 being optimum. 5 is pretty small and will make it difficult to build a horn box which will sit on top and have the same dimensions. Any comments?

My experience to date is limited to the 9846 in stock form w/networks recapped with Dayton 5% poly's. I would defer to others here.

2- I have read that mounting the speakers close together in the vertical plane will result in better overall sound. Or can they be too close?

The closer drivers are in proximity to each other, the closer you get to a "point source". One potential caveat could be reflections from a protruding horn bell, defer to the experts again.

There is a discussion on the Altec site about placement of the horn above the woofer. Align the voice coils, align the mounting flanges or align the outer radius of the horn with the woofer. What's the deal there?

ideally, align the acoustic centers. How to determine the acoustic centers? Zilch may have posted these numbers for the 511 and 811 with various drivers in one of the AK or LH threads, hopefully he'll(or another of our residents) discover this thread and offer some input.

Apparently when wiring the woofer and horn the polarity on the horn is reversed as it's diapragm moves opposite the woofer and it should be done this way to properly phase them. True?

With a 2nd order network yes generally true, this is usually addressed in the stock wiring schemes such that in a factory system the red wire will still go to the HF + terminal, but if you trace the wire back to the network, you'll find it terminated to -/gnd.

5- when setting the x over point can that be done with a meter on the output terminals of the x over box? Reading hz or voltage? If voltage what is it for 500 hz?

The XO point is determined by the combination of component values and the impedance of the drivers/load. It's very important to understand that 8 ohms and 500hz are "nominal" figures. measuring the crossover point and slope will require more than a MM, and beyond curiosity probably isn't all that necessary.

I don't know what the hf drivers are as there's no part or id #. The #7779 is ink stamped on the end and the #301339 is stamped on the OD of the driver. Anyone know which they are?

Can you post a couple pics? a side shot so we can determine the depth of the driver, and a shot of the diaphragm, you need only remove the rear cover to expose the diaphragm provided it doesn't use a loading cap. Utmost care should be used when opening a driver, work area must be free of magnetic objects that might be "grabbed" by the drivers magnetic field as said objects will usually crash into the dome of the phragm effectively destroying it, this includes the cover screws.

[whitebroncoii]

1- Altec specifies a sealed enclosure ( like a 9846) for my 411's. They also specify a volume of 4-8^3 ft with 5 being optimum. 5 is pretty small and will make it difficult to build a horn box which will sit on top and have the same dimensions. Any comments?

One idea is to place the horn mouth even with the front edge of the woofer enclosure and let the throat and driver extend behind the stacked system if needed.

2- I have read that mounting the speakers close together in the vertical plane will result in better overall sound. Or can they be too close?

The high and low devices need to be close enough that you cannot hear them in the listening field. The further away the listening position, the less critical.

3- There is a discussion on the Altec site about placement of the horn above the woofer. Align the voice coils, align the mounting flanges or align the outer radius of the horn with the woofer. What's the deal there?

The concept is aligning the arrival time from the two sources (acoustic center). A quickie method is the align the voice-coils. However, the voice-coil is not the acoustic center on most components. An old Altec method is to physically move the horn forward-backward to get alignment. This method actually works very well. Put a tone through your system at, or near the crossover frequency. Move the the horn and listen to the tone. It should get louder or lower. Find the spot where it is loudest or lowest. Leave the high frequency driver connected to get the loudest output at crossover. You have now put the HF and LF in phase at crossover. Ignore the electrical polarity.

4- Apparently when wiring the woofer and horn the polarity on the horn is reversed as it's diapragm moves opposite the woofer and it should be done this way to properly phase them. True?

See above #3

5- when setting the x over point can that be done with a meter on the output terminals of the x over box? Reading hz or voltage? If voltage what is it for 500 hz?

A dB meter or voltmeter and a signal generator can be used to determine crossover frequency. Connect the meter to the high frequency driver terminals (these are should already be connected to the crossover). Set the signal generator for 1V out and a frequency around the center of the band, maybe 5kHz. Connect the generator to your power amplifier with the volume all the way down. Increase the volume of the amplifier until you get a good dB reading on the crossover output (1V rms). This could get really loud and you may want to put the speaker in a closet. Slowly reduce the frequency until you see a 3dB drop (0.7V rms). This is the corner frequency of the crossover's HP filter. Repeat the process for the LF starting around 100Hz and slowly raising the frequency.

[nikki1]

Thank you both for your comments. Now to a really embarrasing confession. The woofers are 416-8A's not 411's. I discovered this after speaking with Bill. I feel like such an idiot that I almost ceased posting. So that takes us back to the good enclosure question. If you all are not not totally disgusted I'd like some recommendations. Still like the A7 500 which goes with the 416's.

It's a bitch to get old-----

Lee

[bowtie427ss]

Thank you both for your comments. Now to a really embarrasing confession. The woofers are 416-8A's not 411's. I discovered this after speaking with Bill. I feel like such an idiot that I almost ceased posting. So that takes us back to the good enclosure question. If you all are not not totally disgusted I'd like some recommendations. Still like the A7 500 which goes with the 416's.

It's a bitch to get old-----

Lee

Oh, so you're human eh?

Pretty sure this more or less assures you'll fit in here.:welcome:

[Altec Best]

I feel like such an idiot that I almost ceased posting. I'd like some recommendations. Still like the A7 500 which goes with the 416's.

Hey Lee, That would have been a mistake, glad you decided to stay.We are all here to learn from one another period.You can teach an old dog some new tricks on occasion too.But not much on this board.Many a wise man hang out in these parts ! So your in good hands.


:welcome: to the board BTW. I'm kind of partial to the 802-8G but the 902-8A is another favorite.And both sound quite nice with any 416. :2thumbsup:

[nikki1]

Thanks fellas. Now I don't feel quite so much the dweeb. Any of you guys mess around with bikes? That's my main passion. HD's and the Italian stuff mostly.

What about the A7's? Good choose?

[bowtie427ss]

What about the A7's? Good choose?

Sure they are!

What are your musical and listening preferences?

I built a pair, then another pair for a buddy. Much akin to the bikes this "hobby" can get a bit out of hand. My A7's led me to want bass extension, welcome home to some more woofers in their own large displacement boxes.

Then, i wanted the Altec flavor in a smaller package for my den and bedroom, welcome home model 15's and 9849-8D monitors.

Then, one of those deals you can't refuse comes along, welcome home a 6 pack.................. of 9844A monitors(down to just one pair now).

One day a hankering for the utmost in LFE from an altec crosses paths with a discussion about the 411 woofer while simultaneously an opportunity on pair of 9846 monitors comes along.............. welcome home.

Finally, sentiment and fond memories of cutting my hifi teeth on model 17's demands that i must have some 604-8G's in 620 cabinets................... welcome home to a pair and some spares.

I keep toying with myself thinking that downsizing must occur, and really it must eventually. But, when it comes right down to it i just cannot make myself part with any of these.............. i'm a friggin Altec addict plain and simple.

I'm pretty sure this is a legitimate illness, be careful what you wish for as you are now in the process of assimilation.

[Altec Best]

i'm a friggin Altec addict plain and simple.

I'm pretty sure your not alone in that regard.It seems my Altec collection keeps growing and growing.I'm going to have to start making apartments/condos out of them ! Because they just keep getting bigger and bigger !

[nikki1]

Oh man, you've got it BAD. I'm the same way with bikes and it's a real curse. Couple that with being an anal perfectionist and it's a wonder my wife's still around. I keep threatening to get a cot, coffee maker, microwave and little fridge and just move down there so I can fiddle 24/7.

Thanks for the + on A7's. I'm going to build them.