Altec horn crossover

roccus

roccus

Active Member
I want to run a pair of Altec horns with 808-8B drivers with 811B horns but will be putting GPA 802-8G diaphragms in them. I need to make a cross over to protect the drivers from blowing using a PL400 amp. I plan on bypassing the mids and tweeters in my speakers and just us the woofer with the Altec horns. I don't know a whole lot about crossovers but was thinking of a design something like this then would need to figure out values for the components. I do know it is not safe to go below 800hz with these drivers. Any input or advise would be helpful.
MyXO_zps28sf4k1l.jpg
 
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Scratch the first one a friend just sent me this, now I see exactly how to build this but I think I still need to get the crossover to cut some of the power down from the 400 to keep from blowing out the diaphragms in the drivers..
n1201-8a_zpskdf2pfdj.jpg
 
roccus said:
but I think I still need to get the crossover to cut some of the power down from the 400 to keep from blowing out the diaphragms in the drivers..
Click to expand...
This is why there's an L-pad, or stepped attenuation on every network Altec built for compression drivers. Because of the sensitivity mismatch in almost any speaker system, you MUST have a way to attentuate the HF.

If you interpret the N1201 wiring diagram correctly, you will see there's two L-pads incorporated there, one to attenuate mid frequencies and one to attenuate high frequencies.
 
bowtie427ss said:
This is why there's an L-pad, or stepped attenuation on every network Altec built for compression drivers. Because of the sensitivity mismatch in almost any speaker system, you MUST have a way to attentuate the HF.

If you interpret the N1201 wiring diagram correctly, you will see there's two L-pads incorporated there, one to attenuate mid frequencies and one to attenuate high frequencies.
Click to expand...
Right now I just want to do it for the horns..... This looks like what I am going to build modeled after the N809-8A
My809_zpsh2pgnh3c.jpg
 
Don't use an 800Hz crossover. The high pass section of the Altec Model 19 crossover above is designed for a 1200Hz crossover point which will provide good protection for the driver and take care of the home use loading that works best with the 811 horn. It says 800Hz but many horns of this type perform better when crossed a half octave above the spec'd loading point. You'll get smoother sound without the shout some accuse mid/high horns of.
 
kyle said:
Don't use an 800Hz crossover. The high pass section of the Altec Model 19 crossover above is designed for a 1200Hz crossover point which will provide good protection for the driver and take care of the home use loading that works best with the 811 horn. It says 800Hz but many horns of this type perform better when crossed a half octave above the spec'd loading point. You'll get smoother sound without the shout some accuse mid/high horns of.
Click to expand...
Thanks for input
 
Agree with @kyle - Use a 1200 Hz frequency for your filter. An 811B horn is not designed to go lower than that anyway. If you had a 511B horn, you might have a shot at making it work.
 
I used the econowave crossovers on 806/811b with good results. Cheaper to build than the Model 19 type, they are a 1200hz cutoff also.
 
The 1200hz XO point limit is more relative to the tangerine equipped small format driver than any horn.

Altec didn't cross them below 1200 for good reason, and if your ears work, you probably won't either.

Again, if your ears work, and you have half a clue about what you are doing, 811's will play as wonderfully at 800hz all day long as a 511 will play down to 500 hz all day long. We're talking hifi/listening room applications, NOT sound reinforcement/concert PA applications.

The issue with the horns is the same with just about any horn one might take the time to analyze. They provide very little acoustic load at their designed cutoff which makes it easier to overdrive them at those frequency extremes. They are hardly the only two horns on the planet that exhibit this characteristic.
 
I think this is the version I built for lower than 95b sensitivity woofers. There are other versions in the e-wave thread. I built them for the Selenium/JBL 220I drivers but decided to try them on the Altecs. Sitting on top of Karlson cabs. with Bozak full rangers was a pretty sweet setup! Then they went atop Altec A7- Then came 511b horns- then 805b horns-Then Model 19 crossovers- then Altec active Crossover lol.
 

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roccus,

If you want to build a " Cheap & Cheerful " econo hipass for your 802s here's one that I just cooked up.
- It's for the 8 ohm 34647 diaphragm when mounted in an 802G, 802T or 808-8B body ( housing a tangerine type phase plug ).

This hipass is set at @ 1K and is as simple as it can get.

This was XSimed using ( response + impedance ) measurements taken from my Altec 802T driver and ZXPC BiRadial horn.

802T-34647_BiRadial_Simple_3-Pole_.png


This design has done away with all the mid-band adjustments, essentially "baking in" all the mid-band attenuation that one > I might want ( "C1" does this due to its small value ).
- FYI, 1950's + 60's era Altec networks used to do similar by using a 4uF cap in that same position (see the bottom pic of the N800F for an example )

One can see ( from the minus 10db trace ) that the 2 traces track each other really quite well ( whether that matters to you ).

Here are links to my recommended parts ( price vs performance, etc. etc. ) coming in at under $22. a channel ( definitely Econo! ).

2 mH Coil = Dayton Crossover Coil 257-554

3.3uF Capacitor = Audyn MPP Capacitor 027-112

5.6uF Capacitor = Audyn MPP Capacitor 027-115

50 Watt LPad = 50 Watt Lpad 260-255

Assuming this is for home use only , you don't really need any extra protection put into the circuit ( as long as you're somewhat responsible with the volume knob ).

Even if that "Flame Linear" PL400 decides to go DC on you, the capacitors will prevent dc from burning out your expensive diaphragms.
- I'd be worrying more about the woofers in your ( unknown to us ) bass circuit ( which are most likely unprotected ).

:)

PS;

N-500-E.jpg

N-800F_Schematic.jpg
 
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EarlK said:
roccus,

If you want to build a " Cheap & Cheerful " econo hipass for your 802s here's one that I just cooked up.
- It's for the 8 ohm 34647 diaphragm when mounted in an 802G, 802T or 808-8B body ( housing a tangerine type phase plug ).

This hipass is set at @ 1K and is as simple as it can get.

This was XSimed using ( response + impedance ) measurements taken from my Altec 802T driver and ZXPC BiRadial horn.



This design has done away with all the mid-band adjustments, essentially "baking in" all the mid-band attenuation that one > I might want ( "C1" does this due to its small value ).
- FYI, 1950's + 60's era Altec networks used to do similar by using a 4uF cap in that same position (see the bottom pic of the N800F for an example )

One can see ( from the minus 10db trace ) that the 2 traces track each other really quite well ( whether that matters to you ).

Here are links to my recommended parts ( price vs performance, etc. etc. ) coming in at under $22. a channel ( definitely Econo! ).

2 mH Coil = Dayton Crossover Coil 257-554

3.3uF Capacitor = Audyn MPP Capacitor 027-112

5.6uF Capacitor = Audyn MPP Capacitor 027-115

50 Watt LPad = 50 Watt Lpad 260-255

Assuming this is for home use only , you don't really need any extra protection put into the circuit ( as long as you're somewhat responsible with the volume knob ).

Even if that "Flame Linear" PL400 decides to go DC on you, the capacitors will prevent dc from burning out your expensive diaphragms.
- I'd be worrying more about the woofers in your ( unknown to us ) bass circuit ( which are most likely unprotected ).

:)

PS;


Thanks for this it is great stuff... no worry about the flame linear it has a DC protect in it... it has been fully WOPLed..... so you didin't use an Lpad in this to fine tune it??

"( as long as you're somewhat responsible with the volume knob )."
ah Huston we might have a problem with that lol

My lowers can handle it no problem I built these 20+ years ago to go along with a Carver TFM 55 I had, they have tuned ports out the back, I plan on disconnecting the mids and bullet tweeter and set the Altec horn on top for now...
P1019589.TIF_zpsiyufgb4s.jpg

Here is my flame linear
wpl_zpstlffcmy8.jpg

ca1_zpsyknxg8m3.jpg
Click to expand...
 
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Looks like I will be going with 808-8B drivers this one is in great condition 7.1 ohm I got a good deal on one on fleabay so now will watch for another one to match it...
my808_zps1kpomrrf.jpg
 
I have a chance to get a pair of 511B horns for practically nothing just pay shipping, but they are so big I kinda have my heart set on 811B's but really need to consider the 511's as can't beat the price, but then that would change the whole crossover, right?
 
roccus said:
I have a chance to get a pair of 511B horns for practically nothing just pay shipping, but they are so big I kinda have my heart set on 811B's but really need to consider the 511's as can't beat the price, but then that would change the whole crossover, right?
Click to expand...

You could easily use the crossover that I posted with 511b horns.

There'll be a more audible difference due to using that symbiotic diaphragm ( when compared to the all aluminum 34647 type ).

With that symbiotic diaphragm you might want to hook back up those tweeters ( using something like a straight 1.5uF cap ) to restore some lost shimmer .

:)

PS; that's a nice looking PL400!
 
roccus said:
I have a chance to get a pair of 511B horns for practically nothing just pay shipping, but they are so big I kinda have my heart set on 811B's but really need to consider the 511's as can't beat the price, but then that would change the whole crossover, right?
Click to expand...

I have 511's and love them. You could cross them at 800 like you originally intended to do with the 811's and see. Probably be fine. Once I heard the 511's the 811's were made gone in short order.
 
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