Multiple horns vs. multiple LF drivers

I wanted to know if anybody has used multiple horns with one LF driver as opposed to using one horn with multiple LF drivers which I see frequently. I ask because I was considering the arrangement of most orchestras which include only one or two tubas seated in the back as more would likely overpower the rest of the orchestra. My second reason for asking is I am planning on building a set of Altec model 19s and now have a set of 511 horns and another set of 811 horns with drivers for all 4 horns. I would build the 811s into the cabinets and mount the 511s on top so the horns would be stacked over the LF driver. I would have crossover considerations to deal with as well. Any thoughts would be appreciated.

Horns are much more efficient than low frequency drivers. I think that is the reason to use more than one low frequency driver. If you use each pair of horns for dedicate frequency band than it is only matter of attenuating each pair of horns to match low frequency driver output.

Yes, the reason for two or more woofers per horn is due to driver sensitivity.

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Originally Posted by Steve56

I wanted to know if anybody has used multiple horns with...

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I’ll assume your intended application is domestic Hi-Fi use. If that’s the case, you should test your four HF drivers, pick the best pair and put them on the 511 horns. Using multiple horns will degrade the performance of your system.

I suggest testing the drivers as these vintage parts are rarely still in spec. I suggest using the 511 horns as they simply sound better than the 811 horns. Altec likely chose the 811 for the Model 19 for aesthetics. The 511s will transition with your woofers better and therefore they will have less of that horn “honk” sound if you design your crossover correctly.

All this said, based on your unusual questions I’m going to guess you haven’t designed numerous speaker systems with Altec or JBL parts. That being the case, I would suggest you try to duplicate an existing system like the Model 19 as closely as possible. There are lots of design decisions made in the design of a system like these and trying to get close may not give you the results that you would like. Speaker design is not like horseshoes.


Widget

Quote:

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Originally Posted by Steve56

I wanted to know if anybody has used multiple horns with one LF driver as opposed to using one horn with multiple LF drivers which I see frequently. I ask because I was considering the arrangement of most orchestras which include only one or two tubas seated in the back as more would likely overpower the rest of the orchestra. My second reason for asking is I am planning on building a set of Altec model 19s and now have a set of 511 horns and another set of 811 horns with drivers for all 4 horns. I would build the 811s into the cabinets and mount the 511s on top so the horns would be stacked over the LF driver. I would have crossover considerations to deal with as well. Any thoughts would be appreciated.

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Steve, For your entertainment you might want to take a look at my Altec build, seen here:

http://audiokarma.org/forums/index.p...onents.766911/

You might get a few ideas here. I liked the Model 19, Model 606, and the 511 horns, and ended up essentially combining them all into a finished product that I am quite pleased with.

GeeDeeEmm

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Originally Posted by gdmoore28

Steve, For your entertainment you might want to take a look at my Altec build, seen here:

http://audiokarma.org/forums/index.p...onents.766911/

You might get a few ideas here. I liked the Model 19, Model 606, and the 511 horns, and ended up essentially combining them all into a finished product that I am quite pleased with.

GeeDeeEmm

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Hello, Thank you all for you input. These will be used in my home. I am in the beginning design phase and have a little wood working experience & electronics experience. I purchased a set of Model 14's new back in 1982 and still have them as my primary speakers. I had to take them home one at a time in a Triumph TR-6 with the roof down and could not use 5th gear. Can't imagine how that would have worked with model 19s. I first heard model 19s in a hi end hi-fi shop when I was 18 and the sound just blew me away. The 14s have been great all these years and I have had the LF drivers refoamed once in 1996 and re-capped the crossovers last year. I have had it in my mind to "upgrade" to the model 19s for a while and wanted to try building a set with original parts.
I have a book by Badmaieff and Davis called "How to build Speaker Enclosures" which has a lot of nice information. Using the 511 horns in the enclosure would require more depth in the cabinet, so I was thinking of building the 811s into the cabinet and mounting the 511s on top. The book suggests aligning the HF Diaphragm with the base of the cone in the LF driver (Sorry, I forgot the proper terms used in the book) roughly. I have a set of 800 series and a set of 900 series HF drivers in boxes in my closet somewhere. I also have an extra set of model 14 crossovers that I re-capped when I did my originals last year. The 14 crossovers work at 1500 Hz and the model 19s were crossed at 1200 Hz, so I will do something about that I think. The LF drivers I just purchased are a pair of 416-8Bs that were previously re-coned in 2002 and one has a repair on it, so I intend to get them re-coned hopefully by GPA.
I'm not limited by size for the cabinets (within reason), so I can alter the original cabinet dimensions if I need to. I'm considering what material(s) I want to use. Some combination of 3/4" plywood and MDF seems doable. I was thinking 3/4" MDF for the back and front panels. I have plenty of time on my hands and this will be a long term project.

Quote:

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Originally Posted by gdmoore28

Steve, For your entertainment you might want to take a look at my Altec build, seen here:

http://audiokarma.org/forums/index.p...onents.766911/

You might get a few ideas here. I liked the Model 19, Model 606, and the 511 horns, and ended up essentially combining them all into a finished product that I am quite pleased with.

GeeDeeEmm

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Hi, thanks for your input. I noticed your horns are painted blue and wanted to know if that is a damping coating? I've seen some on eBay and was curious if you found that this improved the sound by reducing ringing of the horns? If so, what is used to coat the horns and where might I find it?

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Originally Posted by Mr. Widget

Yes, the reason for two or more woofers per horn is due to driver sensitivity.

I’ll assume your intended application is domestic Hi-Fi use. If that’s the case, you should test your four HF drivers, pick the best pair and put them on the 511 horns. Using multiple horns will degrade the performance of your system.

I suggest testing the drivers as these vintage parts are rarely still in spec. I suggest using the 511 horns as they simply sound better than the 811 horns. Altec likely chose the 811 for the Model 19 for aesthetics. The 511s will transition with your woofers better and therefore they will have less of that horn “honk” sound if you design your crossover correctly.

All this said, based on your unusual questions I’m going to guess you haven’t designed numerous speaker systems with Altec or JBL parts. That being the case, I would suggest you try to duplicate an existing system like the Model 19 as closely as possible. There are lots of design decisions made in the design of a system like these and trying to get close may not give you the results that you would like. Speaker design is not like horseshoes.


Widget

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Correct, I'm using in a domestic setting. I intend to get the LF drivers re-coned by GPA (416-8Bs), I have a set of 800 series HF drivers and a set of 900 series HF drivers (In boxes lost in my closet somewhere). What would you recommend for checking/repairing the HF drivers? The 811s would fit the original specs for cabinet size, but I can modify to fit the 511's.

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Originally Posted by Steve56

Correct, I'm using in a domestic setting. I intend to get the LF drivers re-coned by GPA (416-8Bs), I have a set of 800 series HF drivers and a set of 900 series HF drivers (In boxes lost in my closet somewhere). What would you recommend for checking/repairing the HF drivers? The 811s would fit the original specs for cabinet size, but I can modify to fit the 511's.

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Steve,
I studied my project until I was overwhelmed with information, but several points of agreement by all parties kept showing up:

1. The 511 horns are preferred over the 811 because they can be crossed over lower, with most Altec devotees agreeing that the 511 works best crossed at 800Hz or above, while the 811 works better crossed at 1000Hz or above. Regardless, there is general agreement that the 511 simply sounds better.

My experimentation with damping agrees with several others: the ringing in 511/811 horns emanates from the flared outer lips and not from the horn body, and if they are solidly mounted in enclosures, the ringing is not an issue anyway. I did a lot of experimentation with damping on mine, and in the end I could hear no difference, even if I damped the flares. Mount them and don't worry about damping. (These remarks pertain to home use; prosound use would be a different story.)

2. Thick and heavy cabinet panels cure a thousand problems. The happiest results seem to come from front and rear panels that are 1.5" thick and made from two sheets of mdf. I carried that philosophy thru to the rest of the enclosure - minimum 1" thick side panels, and top and bottom panels that are 1.5" and 1".

I additionally went with trapezoidal cabinets because the shape of them practically eliminates standing waves inside the cabinet, as well as allowing for corner placement. The need for internal damping is almost eliminated.

With only 6.5 cu.ft. of cab volume, my 416s have an F3 of 42Hz. It's the most pleasing bass response quality that I've yet achieved with any other build. Perfect for the pop/rock/blues music that I listen to.

(Horn color: they look blue only in photos. In person they are the original Altec blue-green, and were carefully matched to the factory paint.)

GeeDeeEMM

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Originally Posted by Steve56

Correct, I'm using in a domestic setting. I intend to get the LF drivers re-coned by GPA (416-8Bs), I have a set of 800 series HF drivers and a set of 900 series HF drivers (In boxes lost in my closet somewhere). What would you recommend for checking/repairing the HF drivers? The 811s would fit the original specs for cabinet size, but I can modify to fit the 511's.

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If your 800 series drivers have the orange plastic "tangerine" phase plugs I would send them back to GPA and have them rebuild them as necessary. The Model 19 used the 802-8G driver with a very specialized crossover network.

Once you have the correct drivers suitably reworked to bring them up to spec, you'll need to locate or custom build the networks. There have been discussion threads on this forum by Zilch and others on building these networks. Someone with more Altec knowledge than I have should be able to help you with them.

Lastly on the horns; I'd stick with an absolutely stock Model 19 but modify the cabinets as you suggest and go with the 511 horns. I think the results of this "Super" Model 19 should deliver a very satisfying loudspeaker.


Widget

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Originally Posted by Mr. Widget

If your 800 series drivers have the orange plastic "tangerine" phase plugs I would send them back to GPA and have them rebuild them as necessary. The Model 19 used the 802-8G driver with a very specialized crossover network.

Once you have the correct drivers suitably reworked to bring them up to spec, you'll need to locate or custom build the networks. There have been discussion threads on this forum by Zilch and others on building these networks. Someone with more Altec knowledge than I have should be able to help you with them.

Lastly on the horns; I'd stick with an absolutely stock Model 19 but modify the cabinets as you suggest and go with the 511 horns. I think the results of this "Super" Model 19 should deliver a very satisfying loudspeaker.


Widget

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Thank you for your help. I just shipped my 416s to GPA this week for re cone job. Now I need to locate the collection of HF drivers I think I put somewhere in a closet. I'm pretty sure I have a set of 800 series and another set of 900 series. I will have to dig them out to see. I do want to stick to near stock cabinets, but I also want to use MDF in front and rear and use plywood for rest. I will go ahead and use the 511s as suggested, but my book says the face of the HF driver should be in the same vertical plain as the base of the cone of the LF driver. Doing so would make the horn stick out over the base of the cabs. Have to think about that. Also need to research the crossovers too. I have a spare set of model 14 crossovers, but the crossover point is too high (1500 Hz).

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Originally Posted by gdmoore28

Steve,
I studied my project until I was overwhelmed with information, but several points of agreement by all parties kept showing up:

1. The 511 horns are preferred over the 811 because they can be crossed over lower, with most Altec devotees agreeing that the 511 works best crossed at 800Hz or above, while the 811 works better crossed at 1000Hz or above. Regardless, there is general agreement that the 511 simply sounds better.

My experimentation with damping agrees with several others: the ringing in 511/811 horns emanates from the flared outer lips and not from the horn body, and if they are solidly mounted in enclosures, the ringing is not an issue anyway. I did a lot of experimentation with damping on mine, and in the end I could hear no difference, even if I damped the flares. Mount them and don't worry about damping. (These remarks pertain to home use; prosound use would be a different story.)

2. Thick and heavy cabinet panels cure a thousand problems. The happiest results seem to come from front and rear panels that are 1.5" thick and made from two sheets of mdf. I carried that philosophy thru to the rest of the enclosure - minimum 1" thick side panels, and top and bottom panels that are 1.5" and 1".

I additionally went with trapezoidal cabinets because the shape of them practically eliminates standing waves inside the cabinet, as well as allowing for corner placement. The need for internal damping is almost eliminated.

With only 6.5 cu.ft. of cab volume, my 416s have an F3 of 42Hz. It's the most pleasing bass response quality that I've yet achieved with any other build. Perfect for the pop/rock/blues music that I listen to.

(Horn color: they look blue only in photos. In person they are the original Altec blue-green, and were carefully matched to the factory paint.)

GeeDeeEMM

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Wow, you have done a lot of design work. I started thinking of accordion style for the side panels, but then the joinery becomes more complex. Anyway, you made me think a lot! My room is fairly large, so I don't need to use trapezoidal shapes and I wanted them to be close to model 19 cabinets in size and shape. I will use your ideas about the MDF, solid for front and back and maybe a combination for other panels. Hope I don't need a crane to move them. I think I will make the top sections for the 511's a little easier to remove for moving them, not sure how yet. Just shipped 416s off to GPA for re-coning this week. Have to find the HF driver collection somewhere in a closet.
Seems odd that the horn ringing comes from the lips at the end. I will leave mine alone but wondered if you painted them with POR-15 (I think) if that would fix it. POR-15 is sold at auto parts stores. Hardens into a semi-flexible thick coating used to cover rust. I used it to recreate original coating on antique hand planes. Very tough and dries to gloss black.

I think you are on a good path with your plans. A single horn with the newly reconed 416s will yield great results. Your primary concern is going to be building a good crossover network. I'm sure others will chime in with recommendations, but the one addition that I made to my crossover that made the most improvement was the incorporation of the Altec 30923 horn eq/attenuation network. This simple network (three resistors and one capacitor) is inserted between the hi frequency output of the crossover and the compression driver, and removes about 6-8 decibels of the mid-frequency peak that makes the 802 (and most other drivers of the era) sound "honky." The difference is literally day and night.

If you decide to build one of the "Z-19" crossover variants, you will not need the 30923, as an adjustable version of it is part of the crossover.

Finally, I've used POR-15 on various auto restoration projects since the late 1970s. It's a great product. But I don't think it will produce one ounce of damping for the horn. This is because POR-15 produces a relatively thin coating that is rock-hard and almost becomes part of the horn itself. It will make the horn casting a little bit thicker, for sure, but I'm quite sure that the only result is that the horn will simply ring at a different frequency - but it will still ring.

Others will likely add to the thoughts on this subject, but my personal experience with using the 802/511 combo in a home speaker system leads me to believe that the ringing is simply not an issue worth devoting much time or money. Just make sure that the horn is solidly mounted in the cabinet and you will be home free.

GeeDeeEmm

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Originally Posted by Steve56

I will go ahead and use the 511s as suggested, but my book says the face of the HF driver should be in the same vertical plain as the base of the cone of the LF driver. Doing so would make the horn stick out over the base of the cabs. Have to think about that. Also need to research the crossovers too. I have a spare set of model 14 crossovers, but the crossover point is too high (1500 Hz).

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None of the speakers discussed in the Alexis Badmaieff and Don Davis book are really time aligned and other than understanding about the issues of gross misalignment in large theater systems I’m not sure these issues were really explored much in 1966 when their book was written and first published. FWIW: I have my owned a copy of the book since 1977 and had reread it numerous times over the years and am always impressed by the level of knowledge these guys had when looking back on it with the benefit of the decades of advances in understanding the fundamentals in speaker design and measurement technologies.

All that said, the additional delay of the longer horn length of the 511 horn vs. the 811 may affect audible performance, but I doubt it. The stock Model 19 is already out of alignment and swapping the 811 for the 511 will slightly increase this situation. Since you have both horns, I’d mock both up and see what you think.

Regarding these horns and their inherent ringing, I agree with GDM. Once they are properly mounted in a cabinet, the ringing is pretty well dampened. If you choose to go beyond that, cool, but that is just a minor tweak.

Lastly, and I can’t stress this enough. 90% of what makes the Model 19 such a good speaker is it’s refined purpose built crossover and built-in equalizer circuit. If you use a generic crossover you will not even be close to the sound you’re after.


Widget

I had planned on making the upper box removable for moving purposes so I can skip the tank treads on the bottom:). So I will think about making the upper box longer and/or moving it forward and see how much overhang there would be. Maybe just lessen the difference instead of eliminate it.
I have a set of model 14 crossovers and I know they have a different crossover point (1500 vs. 1200 Hz) and are for different drivers. I have a schematic of the 19s crossovers and wonder if I could swap in the model 19 valued parts? Would be easier to compare if I could find a schematic for the 14s crossovers. I understand that just using a different set of Altec crossovers won't give good results because they were designed with specific drivers and uses such as A7s were designed for large auditoriums and high volumes like in movie theaters. 14s are similar in that they are designed for home use and have 2 drivers, so maybe? Otherwise, I would go with model 19s or take a look at the z-19s.

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Originally Posted by gdmoore28

I additionally went with trapezoidal cabinets because the shape of them practically eliminates standing waves inside the cabinet, as well as allowing for corner placement. The need for internal damping is almost eliminated.

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I am not a expert at these things, but I do not believe the statements above are true. (I have some kind of trapezoid shape cabinets myself). I have read knowledgeable people stating that there will be kind of the same total amount of standing waves as with other simpler shapes, just more complex to calculate, and maybe more spread out in frequency and time.
I myself did not use these as arguments for going for trapezoid shape. But as you, I want to be able to place them deep into corner.
Can you post a pic of your cabinets?

Quote:

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Originally Posted by gdmoore28

I think you are on a good path with your plans. A single horn with the newly reconed 416s will yield great results. Your primary concern is going to be building a good crossover network. I'm sure others will chime in with recommendations, but the one addition that I made to my crossover that made the most improvement was the incorporation of the Altec 30923 horn eq/attenuation network. This simple network (three resistors and one capacitor) is inserted between the hi frequency output of the crossover and the compression driver, and removes about 6-8 decibels of the mid-frequency peak that makes the 802 (and most other drivers of the era) sound "honky." The difference is literally day and night.

If you decide to build one of the "Z-19" crossover variants, you will not need the 30923, as an adjustable version of it is part of the crossover.

Finally, I've used POR-15 on various auto restoration projects since the late 1970s. It's a great product. But I don't think it will produce one ounce of damping for the horn. This is because POR-15 produces a relatively thin coating that is rock-hard and almost becomes part of the horn itself. It will make the horn casting a little bit thicker, for sure, but I'm quite sure that the only result is that the horn will simply ring at a different frequency - but it will still ring.

Others will likely add to the thoughts on this subject, but my personal experience with using the 802/511 combo in a home speaker system leads me to believe that the ringing is simply not an issue worth devoting much time or money. Just make sure that the horn is solidly mounted in the cabinet and you will be home free.

GeeDeeEmm

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Hello GDEmm,

I am planning on building the crossovers using the Z-19 crossover. I found 2 drawings, but the resistors have different values or one is a mistake. In one the values are 2,3 and 4 Ohms and in the other they are 20, 30 and 40 Ohms? Is one a mistake? Also, what is the crossover point? 1200 Hz? Thank you.

I think that the character in the upper drawing is the letter O and not the number 0.

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Originally Posted by Don C

I think that the character in the upper drawing is the letter O and not the number 0.

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I think you are correct. I didn't think of that and I found a few more parts lists that had 2,3 and 4 instead of 20, 30 and 40. Thank you for helping.

My memory is not what it used to be. I thought I had bought 2 pairs of HF drivers a "few" years ago for my long term project of building a set of model 19's. I forgot where I put them and after 2 weeks of looking I found one set of 806-8As (Not even remotely close to where I had stored them). I thought I had another set of 900 series, but have not found them yet. The label on the box indicated I had bought the 806s more than 8 years ago. Anyway, I just ran across a set of 802-8Gs and bought those. When I opened them up, I found 2 different diaphragms, one having a "909" emblem on it and the other blank. There was some white powder on the "909" diaphragm and the other is clean.

I bought a Kirby vacuum cleaner from goodwill a long time ago. The body was thick aluminum with a lot of corrosion. I remember I had to sand it all off before polishing it back to shiny finish. The powder on the diaphragm looks similar and when I tried to get it off with alcohol and a swab, there were some rough areas left.

Bill at GPA suggested I try them and if they work, go with it. I'm worried that once corrosion starts, it keeps going and I don't think grinding and buffing is an option. Also maybe better to swap out the "909" for an original as Bill said it was made for high power and I don't need that for my living room. Better to have 2 matching diaphragms? I probably would not hear the difference I'm guessing. Also, I don't have any way of testing them before I build the cabinets and crossovers.

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