Need a crossover for my new 400 lb center channel speaker...

http://www.hostboard.com/forums/hbmc...2012/07/34.jpg

http://www.hostboard.com/forums/hbmc...2012/07/35.jpg

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Since this is an old style cabinet, I'm more or less going to have to use these to load it....

http://www.hostboard.com/forums/hbmc...2012/07/37.jpg

The plan is to plunk my 3rd 1005b on top and load it with a 288, prolly a 288b. I'm not going to woory about the extreme highs and lows given the intended purpose.

Anyone know whether or not there is a standard crossover for these units?

i think its closer to 475 lbs..ask me how i know? 515a's!! very nice, ive heard these are the absolute best for voice, that being said they might need a different crossover than the 515b's. phenolic spiders..pure altec porn there! most were using the 500c crossovers

I hope you have a big theater for that monster.

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Originally Posted by cradeldorf

I hope you have a big theater for that monster.

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I wish it was bigger. 45' by about 30' by 10' high is my current listening space.

These are the right and left channel set ups on the 45' wall.

http://www.hostboard.com/forums/hbmc...2012/07/38.jpg

Wow, that is sick!

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Originally Posted by gortnipper

Wow, that is sick!

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I really think he needs a couple rows of par 64's across the ceiling in front of them, and maybe a couple pinspots in the back of the room focused just wide enough to illuminate the speakers themselves. Oh, and about 200 running feet of black backdrop to cover all the pink without undoing it's acoustic goodness. I'm afraid if AA sheetrocks that space, he won't like what it does to the acoustics of it.

Wow, now THAT is a great STACK of Altecs!!

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Originally Posted by bowtie427ss

I really think he needs a couple rows of par 64's across the ceiling in front of them, and maybe a couple pinspots in the back of the room focused just wide enough to illuminate the speakers themselves. Oh, and about 200 running feet of black backdrop to cover all the pink without undoing it's acoustic goodness. I'm afraid if AA sheetrocks that space, he won't like what it does to the acoustics of it.

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Yeah, rock will liven it up and reflect but I gotta' get after the guy for not finishing the walls, the rest of the house is magnificent! I know, a man has to do.....;)

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Originally Posted by westend9

Yeah, rock will liven it up and reflect but I gotta' get after the guy for not finishing the walls, the rest of the house is magnificent! I know, a man has to do.....;)

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Well, the 1600+ sq ft of basement is counted as unfinished space on the tax record, so adding sheet rock really wasn't in the plans to start with. Plus as Tom mentions, I think leaving the insulation exposed helps deaden the room. Besides, it's a Man Cave. It has a commode and pro popcorn maker, but no TP, Alcohol sanitizer and paper towels, but no sink. It was designed to be unattractive to members of the fairer sex.

Anyway, back to the original topic. I've looked up the N500F here, but I don't have any 15067s, nor does this have a schematic. Is Steve Schell still around? He apparently has a schematic for an early N500A, which I'm guessing is close to what I want. Anyone else know a source for a similar late 40's early 50's N500?

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Originally Posted by analog addict

I think leaving the insulation exposed helps deaden the room.

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Better get some burlap and I wonder if that would even help. Fiberglass is as nasty as it's name implies. I have a hard time understanding why it isn't banned along with asbestos. The problem with fabric coverings is that they burn like gasoline.

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but I don't have any 15067s,

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You looked at least a half dozen or so in the eyes while you were here. Lemmee know if you go that route, i can hook you up.

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Anyone else know a source for a similar late 40's early 50's N500?

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Ebay, where they average around 500 a pop for singles. You'll either have the good fortune of crossing paths with one in the wild(which could take way too long), or build a facsimile.

Aren't those early networks a "series" topology?

Considering the resources available to you, why don't you have one built yet?:D

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Fiberglass is as nasty as it's name implies.

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I understand some people have a nasty intolerance for glass. I remain thankful that i'm not one of them, as it's the best speaker damping material and home insulation available to mortal men. It's also great for controlling room acoustics.

You are in for a shock . Look at this 1930 add.

http://www.lansingheritage.org/image...lletins/7a.jpg

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Originally Posted by bowtie427ss

I really think he needs a couple rows of par 64's across the ceiling in front of them, and maybe a couple pinspots in the back of the room focused just wide enough to illuminate the speakers themselves. Oh, and about 200 running feet of black backdrop to cover all the pink without undoing it's acoustic goodness. I'm afraid if AA sheetrocks that space, he won't like what it does to the acoustics of it.

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Originally Posted by westend9

Yeah, rock will liven it up and reflect but I gotta' get after the guy for not finishing the walls, the rest of the house is magnificent! I know, a man has to do.....;)

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Yup I'm with you on this Westend... Just the sight of that insulation breaks me out in hives !! I couldn't hang for long with all those fibers running amok ! :Big smile: Love the speaks though AA ! Just beautiful...

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Originally Posted by LICORNE

You are in for a shock . Look at this 1930 add.

http://www.lansingheritage.org/image...lletins/7a.jpg

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Heh, 14 lb crossovers? Nice if you can swing it. 12 db per octave, crossed over at 500Hz. I need to figger out how to determine the impedance, since I'll have 20 ohm woofers in parallel and a 20 ohm compression driver

The fiberglass doesn't bother me at all. Only if I handle it with bare hands for protracted periods of time does it bother me.

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Originally Posted by analog addict

I need to figger out how to determine the impedance,

since I'll have 20 ohm woofers in parallel and a 20 ohm compression driver

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thats so easy now.



Passive Crossovers, Capacitor and Coil Calculator


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adam west will always be batman to me -


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Originally Posted by analog addict

It was designed to be unattractive to members of the fairer sex.

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CLASSIC!

Firmly ensconced into the Altec Aficionado Club for Men! :cool:

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Originally Posted by analog addict

I need to figger out how to determine the impedance, since I'll have 20 ohm woofers in parallel and a 20 ohm compression driver

The fiberglass doesn't bother me at all. Only if I handle it with bare hands for protracted periods of time does it bother me.

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True AA, but you don't want to be breathing in those tiny fibers either for long periods of time...


Ok so if you have them in parallel then the woofers impedance should be halved 10 ohms.. If you have an 8 ohm compression driver it would make it much easier to match.. Not a big issue though.. This is for car speakers but the application is the same for home speaks as well..

Series Parallel Speaker Impedance

Geez, sorry I brought up the insulation, I was just ribbing the guy. If I was in his shoes, I'd probably be making the same decision about the house.
Back to the crossovers---Those originals are a piece of art. Man, they knew how to build stuff back then. A network with new stuff shouldn't be that difficult to build, I'm thinking.

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Originally Posted by westend9

Geez, sorry I brought up the insulation, I was just ribbing the guy. .

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Lance it is No BIG deal... It's just a personal experience with Fiberglas insulation..AA has heard this before, again No BIG deal...

AA is Happy with it, and that is all that really matters isn't it ? :wink2:

You really need to measure the actual impedance for a good crossover. I'll get over there as soon as I can to measure for you. Might bring a digital x-over so we can play. :D
Maybe this coming Friday or Saturday?

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Originally Posted by Panomaniac

You really need to measure the actual impedance for a good crossover. I'll get over there as soon as I can to measure for you. Might bring a digital x-over so we can play. :D
Maybe this coming Friday or Saturday?

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I have a feeling that we are heading for a good thread on the 210s here. Pano is great in the "systematic reporting back" area. His thread here on the A7s was one of the best. Right now I am just eagerly waiting to see lots of graph-ridden posts, more so b'coz of these particular 515s.

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Originally Posted by Panomaniac

You really need to measure the actual impedance for a good crossover. I'll get over there as soon as I can to measure for you. Might bring a digital x-over so we can play. :D
Maybe this coming Friday or Saturday?

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Friday night is VIP night at the Beer Bourbon and Barbeque Fest across town, and I was lucky enough to score a half price ticket. Sat is a possibility though...
Meanwhile, back at the ranch....


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Oh yeah, I measured the DCR on the 515's, both were in the 9 ohm range, and about 4.6 when paralleled. I'm betting these were closer to 16 ohms. Also, I have this bad boy on a couple of dollies now, and have cleared out my whole main system in preparation for working/final placement.

Many thanks AA for the magnificent pic of the 515s. They seem to be in very good condition. Regarding the 9 ohms DC value, it sounds more like a 12 ohm version of the 515. However it does not matter much, as I am sure they will excel at the job they were meant for.:D

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Originally Posted by aditya

Many thanks AA for the magnificent pic of the 515s. They seem to be in very good condition. Regarding the 9 ohms DC value, it sounds more like a 12 ohm version of the 515. However it does not matter much, as I am sure they will excel at the job they were meant for.:D

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http://www.hostboard.com/forums/hbmc...2012/07/41.jpg

As you can see, they're marked as 20 ohm. What they really are is a good question....

A couple more pix...

http://www.hostboard.com/forums/hbmc...2012/07/42.jpg

http://www.hostboard.com/forums/hbmc...2012/07/43.jpg

Guess I should break out the real camera and get some better quality pix.

Yes, you are right. Your latest pic sure says them to be of the 20 ohms types, but the DC values are way off !
May be its time for the experts to chime in.

I'll post actual impedance curves once I've been back over to A.A's Saturday or Sunday would be good for me.

I pullked the 1005b/288b off the shelf where it had been sitting. When I originally unpacked and tested this one, it sounded distorted. I put it away and didn't screw with it, and was hoping it was just some dirt in the gap/'phragm.

The raw material complete with 50+ years of dust.

http://www.hostboard.com/forums/hbmc...2012/07/50.jpg

Here's a surprise - a loading cap. The screws on the cap all had that little "snap" to them when loosened, making me pretty confident that no one had been in this driver before.

http://www.hostboard.com/forums/hbmc...2012/07/51.jpg

Show me the money! A pristine 288b diaphragm. I didn't see the model number, but I've not found a model number listed for the 288b 'phragms. A pair of 20221s for the 288c went for over $600 on E-Pray last fall, and this one's in better condition than those - not that I'm ever going to sell....

http://www.hostboard.com/forums/hbmc...2012/07/52.jpg

http://www.hostboard.com/forums/hbmc...2012/07/53.jpg


I gently blew out the driver itself and was rewarded with a noticeable puff of dust. I carefully reassembled it, plopped a 7 uF capacitance in series with the + lead, and carefully applied some low wattage music.

http://www.hostboard.com/forums/hbmc...2012/07/54.jpg



Success! The distortion I once heard is gone. So I should be in good shape for Pano this weekend. Oh yeah, DCR on this guy is 14.2 ohms, so it's a real 20-24 ohm 'phragm.

Killer old gear.
Man cave.
Judas Priest vinyl.
This thread just keeps getting better and better!

Almost have the mancave redone...

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Cool! I like the new arrangement. I wonder if that thing should go on its side?

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Originally Posted by Panomaniac

Cool! I like the new arrangement. I wonder if that thing should go on its side?

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Hard to ever put wings on it if it's lying on it's side.....

Here's some of Panomaniac's work....

http://www.hostboard.com/forums/hbmc...2012/08/17.jpg

and here's a hashed together working unit to use while I await the results of his work...

http://www.hostboard.com/forums/hbmc...2012/08/18.jpg

We had a great time last night, A.A. is always a great host and everyone had a blast. We did have some trouble concentrating on the audio, as Olympic Beach Volleyball was on the TV (sound off). :cool
I think we came up with a pretty good crossover by measurement and by ear. It was nice to have some trained listeners there to verify the sound of things. The crossover turned out to be 3rd order electrical with the horn reversed (IIRC). Acoustically the crossover point is circa 770Hz, but I don't remember the electrical points. It's what sounded best.
I'll get some measurement graphs and other info up ASAP - tonight I hope.

EDIT: Oh yeah, the traces you see above are impedance plots for the dual woofers and the horn+driver.

Wish I lived closer ! Sounds like you guys had a great time ! :cool:

OK, here are some pretty graphs. You'll see the 288 on 1005 impedance curve in green - the dual 515s are in blue.
What would you call their nominal impedance?
http://www.michael.mardis.com/images...nce-center.png

On the second graph we see the drivers' measured at the listening position after crossover. Green is the combined response. Don't know why the bass looks so bumpy, might have been where the mic was placed. The crossovers ended up being 3rd order at 600Hz for the low pass, 3rd order 750Hz for high pass. Reverse phase.
http://www.michael.mardis.com/images/final-center.png

I'll work on this some to come up with the values for a passive crossover given the impedance curves. Will post results here.

EDIT: Images updated for better size

Many thanks "Panomaniac" for the graphs. I am yet to see a thread on 210s with real graphs. This will be very useful for ref. sake.

From the impedance graphs it seems the dual 515s (assuming they are in the parallel mode) are really 20-24 ohms each (@ 1 K Hz.), as specified. It is surprising that the DC values are at 9 ohms, as measured by 'AA'. Or may be he also had measured the value in the parallel mode, and while the actual value was at 8 ohms (which also is confirmed by the posted graphs), the extra 1 ohm was the meter leads error.

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Originally Posted by aditya

.......the extra 1 ohm was the meter leads error.

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One ohm for a short piece of wire would be a serious error.

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Originally Posted by Audio_by_Goodwill

One ohm for a short piece of wire would be a serious error.

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Its more to do with the 'contact points' than the short piece of wire.

I didn't get a chance to measure the 515s separately, but in parallel they dip down to about 8 ohms at the lowest. I might call them nominal 20 ohms. From the twin peaks it looks like the box is tuned at about 35Hz.

Doing some work last night I may have a good passive design done. 2 caps and a coil for the low pass - 3 caps, 2 resistors (or L-Pad) and 1 coil for the high pass. I was wrong about needing big inductors (that's good) but the caps will be large. Will post details tonight.

I'm all ears....:biggrin2:

BTW, the 515's are marked as 20 ohms....