Altec

[adityapm]

The suggestions by Hari reminds me of two vintage speaker designs where woofer had no crossover. One is famous Wharfedale sand filled open baffle. Check this link:

Wharfedale SFB/3 | Inner Magazines

SFB/3s was Gilbert Briggs’ take on Peter Walker’s Quad ESL57. Today ESL57 is by far more famous, but SFB/3s has survived as a model for numerous open-back designs.

www.inner-magazines.com

The second is offered by Madisound utilizing Seas drivers based on A26 vintage speakers:

Seas A26 10" 2-way Kit Pair (based on the classic A25)

Seas A26 10" 2-way Kit Pair - a new spin on a true classic! Price is for a PAIR Designed by Håvard Sollien & Diego Ivars at the SEAS R&D laboratory. Seas of Norway and Madisound are excited to provide the A26 speaker kit. This kit utilizes the A26RE4 10" classic paper cone woofer and new...

www.madisoundspeakerstore.com

Both are interesting articles but serious designers don’t approve either of them. I have never personally listened to any or experimented with such simple crossovers but am quite curious as why some are die hard fans.

The very citing of these two examples by you says that probabely you are not much into speaker engineering or you have not really played enough (or not at all) with the Altecs to know where they differ from the others. They are very different animals.

The Altec woofers' (the 515s, 416s, 803s) hall mark is in its magnetic coupling area. It is an example of extreme engineering. They were the first to use rectangular cross-section wires to wind the coils, in order to reduce the gap. It is so close that a standard razor blade (4 thousandth of an inch) even will not fit in it. It is so much so that while fitting it on a baffle if the pressure on each mounting bolt is not equal it will rub the coil. Even the mass of the moving parts (the paper cone, coil, spider etc which is otherwise quite low) will sag the assembly if left in position for long. That's why the speakers are rotated 180 degrees once a year to self compensate the tendency.

All this results in a very low "Q", which makes them very quick, very eager to move. I mean really quick. And this gives the Altecs their mid-range magic, which is their speciality. Their frequency response really extends a lot beyond the mid-ranges.

Woofers or any driver for that matter without crossovers are not standard but special cases. In the 70s and 80s most Japanese boxes were using this to simplify and cheapen out production costs. They were using woofers with heavy cone-assembly and higher inductance coils, both in tandem dampen out and reduce the HF response as desired. But the case here is different. Altecs used the lightest moving-parts and very low inductance coils, around 1.5 mH. These two values do not change with time, but the magnets do weaken.

In the present context, it seems to be a good choice as the user is not in a position to really go for the standard route of tortuous measurements and art (almost Black Art) of designing a crossover, whether passive or active. I personally prefer passive ones as they are capable of controlling the timber also.

The Altecs were the world industry standard for 45 years, and Hari has worked in the industry long enough to say what is only practical.

 

[yogibear]

The very citing of these two examples by you says that probabely you are not much into speaker engineering or you have not really played enough (or not at all) with the Altecs to know where they differ from the others. They are very different animals.

The Altec woofers' (the 515s, 416s, 803s) hall mark is in its magnetic coupling area. It is an example of extreme engineering. They were the first to use rectangular cross-section wires to wind the coils, in order to reduce the gap. It is so close that a standard razor blade (4 thousandth of an inch) even will not fit in it. It is so much so that while fitting it on a baffle if the pressure on each mounting bolt is not equal it will rub the coil. Even the mass of the moving parts (the paper cone, coil, spider etc which is otherwise quite low) will sag the assembly if left in position for long. That's why the speakers are rotated 180 degrees once a year to self compensate the tendency.

All this results in a very low "Q", which makes them very quick, very eager to move. I mean really quick. And this gives the Altecs their mid-range magic, which is their speciality. Their frequency response really extends a lot beyond the mid-ranges.

Woofers or any driver for that matter without crossovers are not standard but special cases. In the 70s and 80s most Japanese boxes were using this to simplify and cheapen out production costs. They were using woofers with heavy cone-assembly and higher inductance coils, both in tandem dampen out and reduce the HF response as desired. But the case here is different. Altecs used the lightest moving-parts and very low inductance coils, around 1.5 mH. These two values do not change with time, but the magnets do weaken.

In the present context, it seems to be a good choice as the user is not in a position to really go for the standard route of tortuous measurements and art (almost Black Art) of designing a crossover, whether passive or active. I personally prefer passive ones as they are capable of controlling the timber also.

The Altecs were the world industry standard for 45 years, and Hari has worked in the industry long enough to say what is only practical.

Played with loads of FRs playing crossover less and I understand what you are trying to convey, however I am yet to play with the Altecs as my current room size is small.

I am more of a die hard doer, experience myself through trial and experiment. Altecs will have to wait untilI get my real estate gets worked out.

 

[Sushant Sharma]

The very citing of these two examples by you says that probabely you are not much into speaker engineering or you have not really played enough (or not at all) with the Altecs to know where they differ from the others. They are very different animals.

The Altec woofers' (the 515s, 416s, 803s) hall mark is in its magnetic coupling area. It is an example of extreme engineering. They were the first to use rectangular cross-section wires to wind the coils, in order to reduce the gap. It is so close that a standard razor blade (4 thousandth of an inch) even will not fit in it. It is so much so that while fitting it on a baffle if the pressure on each mounting bolt is not equal it will rub the coil. Even the mass of the moving parts (the paper cone, coil, spider etc which is otherwise quite low) will sag the assembly if left in position for long. That's why the speakers are rotated 180 degrees once a year to self compensate the tendency.

All this results in a very low "Q", which makes them very quick, very eager to move. I mean really quick. And this gives the Altecs their mid-range magic, which is their speciality. Their frequency response really extends a lot beyond the mid-ranges.

Woofers or any driver for that matter without crossovers are not standard but special cases. In the 70s and 80s most Japanese boxes were using this to simplify and cheapen out production costs. They were using woofers with heavy cone-assembly and higher inductance coils, both in tandem dampen out and reduce the HF response as desired. But the case here is different. Altecs used the lightest moving-parts and very low inductance coils, around 1.5 mH. These two values do not change with time, but the magnets do weaken.

In the present context, it seems to be a good choice as the user is not in a position to really go for the standard route of tortuous measurements and art (almost Black Art) of designing a crossover, whether passive or active. I personally prefer passive ones as they are capable of controlling the timber also.

The Altecs were the world industry standard for 45 years, and Hari has worked in the industry long enough to say what is only practical.

Some great info there. I was aware of the light weight and fastness and the sag if kept oriented in the same position but pressure on the screws/bolts I didn't think of. Like you said there could be so much that is out of spec with these woofers but at least I will do what i can.

Please do share some further detail/insight when time permits, on the A9 cabinet as I have been unable to find any info on them. Thanks

 

[Sushant Sharma]

Calling on the forum altec experts to help with cabinet design. A twin altec woofer in question. Sealed, wideband or front loaded?
Posting excerpts from my internet research;

"To my ears Front Loaded Horn has better dynamics , ease and musicality . Onkens and similar are undisputebly more "hifi' but FLH gets to the essence of the music in a startling way . But of course there are good and bad examples of each approach, and both need a lot of work and experience to get the best out of them .

A front loaded cabinet has far more treble response, and has more stage throw.

A rear loaded cabinet with the exact same speakers has more bass response and is more even across the tonal spectrum.

forgive my total ignorance, but could someone explain what front loaded vs. rear loaded means?
Mounting the speaker from the front of the baffle by putting the magnets through the cutout versus mounting the speaker from inside if the baffle.


Front load = you hear mostly speaker tone. Very little cab coloration.

Rear load = a good one will give you that deep, warm woody 'knock' whilst still being tight and percussive.

I have always found that rear mounted sounds smoother on the topend and fatter

 

[Decadent_Spectre]

Wait, am I correct to understand you bought these drivers without having a plan of what to do with them?

 

[Sushant Sharma]

Wait, am I correct to understand you bought these drivers without having a plan of what to do with them?

The plan was and still is to put them in a box.

There are more than one altec models that house the twin wooferS. 817, A9 (suggested above), 211, 815.

I was hoping somebody might pitch in with some views on the cabinet. In absence I will go ahead with one of the models listed above. I am thinking either the 817 (for which plans are available) or a sealed A9 (but smaller dimensions feom original, which I am afraid doesn't have any plans available)

 

[srinisundar]

All the Altecs drivers such as combination of 515/416 woofers, 288 drivers , 8 cell and 10 cell horns are project based. You cannot settle in one project in one shot, all the boxes sound different and we never know one man's taste of hearing to suggest and it may not be your liking.. This is my opinion. Altec's coaxial are easy to settle in a single shot.

 

[Decadent_Spectre]

The plan was and still is to put them in a box.

There are more than one altec models that house the twin wooferS. 817, A9 (suggested above), 211, 815.

I was hoping somebody might pitch in with some views on the cabinet. In absence I will go ahead with one of the models listed above. I am thinking either the 817 (for which plans are available) or a sealed A9 (but smaller dimensions feom original, which I am afraid doesn't have any plans available)

I see. Thanks for answering.

 

[Hari Iyer]

Hi Sushant,
Sharingca link for A5 which is an interesting VOTT build https://jeffsplace.positive-feedbac...re-restoration-part-2-the-bass-horn-cabinets/

 

[yogibear]

Another option and bass cabinet is my favorite:

GIP 7331 FIELD COIL SPEAKER – M & S | Ultimate High-Fidelity

www.monoandstereo.com

 

[adityapm]

Calling on the forum altec experts to help with cabinet design. A twin altec woofer in question. Sealed, wideband or front loaded?
Posting excerpts from my internet research;

"To my ears Front Loaded Horn has better dynamics , ease and musicality . Onkens and similar are undisputebly more "hifi' but FLH gets to the essence of the music in a startling way . But of course there are good and bad examples of each approach, and both need a lot of work and experience to get the best out of them .

A front loaded cabinet has far more treble response, and has more stage throw.

A rear loaded cabinet with the exact same speakers has more bass response and is more even across the tonal spectrum.

forgive my total ignorance, but could someone explain what front loaded vs. rear loaded means?
Mounting the speaker from the front of the baffle by putting the magnets through the cutout versus mounting the speaker from inside if the baffle.


Front load = you hear mostly speaker tone. Very little cab coloration.

Rear load = a good one will give you that deep, warm woody 'knock' whilst still being tight and percussive.

I have always found that rear mounted sounds smoother on the topend and fatter

Hello Sushant,

I am building a 3 phase welding rectifier machine, and a specific portion had to be finished in one go.

Now coming to your predicament and its solutions, the first thing is not to hurry. These are not reversible things.

The second thing is your audio journey so far. What boxes you have listened to so far ?
What type of music you listen to mostly ?
What instruments you prefer more than others, acoustic or electronics based ?
At what level (how loud) you listen to things ?
What is your over all perception of hi-fi reproduction, like do you prefer heavy (bass), or airy (highs) type of reproduction ?
OR you like the flat-ish sound the way monitors do ?

What is your room height ? Is it the standard 10ft or higher or lower ?
Is the full space available for listening only ?
At what distance you will be for a serious listening session ?


The 416-8c is a Ferrite (not Alnico) driver, and these do not suffer from magnetism losses.

Front loaded/Rear loaded means the horns.
And Front mounted/Rear mounted means the drivers.

A front-loaded horn is visible from the front, as is the case with the 816, 817, A5/7, 815, 211 etc.
A rear mounted horn is enclosed inside the enclosure. Altec has no enclosures here.

A front/rear-mounted driver means as you have already put it ...
"Mounting the speaker from the front of the baffle by putting the magnets through the cutout versus mounting the speaker from inside if the baffle."

Post back the details, and your box will be designed.

 

[Sushant Sharma]

All the Altecs drivers such as combination of 515/416 woofers, 288 drivers , 8 cell and 10 cell horns are project based. You cannot settle in one project in one shot, all the boxes sound different and we never know one man's taste of hearing to suggest and it may not be your liking.. This is my opinion. Altec's coaxial are easy to settle in a single shot.

Srini, Thanks for your feedback. I recall you have multiple altec cabinets built. Must be nice to have choices. Yes, I must be more open to experimenting just wanted to tread cautiously.

 

[Sushant Sharma]

Hello Sushant,

I am building a 3 phase welding rectifier machine, and a specific portion had to be finished in one go.

Now coming to your predicament and its solutions, the first thing is not to hurry. These are not reversible things.

The second thing is your audio journey so far. What boxes you have listened to so far ?
What type of music you listen to mostly ?
What instruments you prefer more than others, acoustic or electronics based ?
At what level (how loud) you listen to things ?
What is your over all perception of hi-fi reproduction, like do you prefer heavy (bass), or airy (highs) type of reproduction ?
OR you like the flat-ish sound the way monitors do ?

What is your room height ? Is it the standard 10ft or higher or lower ?
Is the full space available for listening only ?
At what distance you will be for a serious listening session ?


The 416-8c is a Ferrite (not Alnico) driver, and these do not suffer from magnetism losses.

Front loaded/Rear loaded means the horns.
And Front mounted/Rear mounted means the drivers.

A front-loaded horn is visible from the front, as is the case with the 816, 817, A5/7, 815, 211 etc.
A rear mounted horn is enclosed inside the enclosure. Altec has no enclosures here.

A front/rear-mounted driver means as you have already put it ...
"Mounting the speaker from the front of the baffle by putting the magnets through the cutout versus mounting the speaker from inside if the baffle."

Post back the details, and your box will be designed.

Thanks for taking the time Aditya. Good luck with your build. Here goes,

Focal, Harbeth C7es3, Magnepan LRS (for a couple of months) Spendor LS3/5a and then Lyrita Horne grande 15 inch to presently altec 416 8c (temporary box from another speaker project) with altec 288c.

Listen to jazz more and a bit of an assortment ranging from pop to Indian classical.
Listen to acoustic instruments mostly. Not much electronic.
70 to 90 db I think (not too sure decibel wise)
Maybe crank up the volume slightly more sometimes.
Prefer a bit of meat on the bones. Prefer Fat and thick tone to airy and crisp.
Ceiling height is about 9.5 ft
It's a living room situation and I sit approx 16ft away from the speakers with the back wall being another 6 ft away. Part of this room then opens into an open kitchen.
Hope these details help. Look forward to hearing from you. Thanks

 

[Sushant Sharma]

Difficult waiting on kindness of strangers. I filled out a questionnaire.

Else I threaten to share my experiments with you all soon. Thanks all.

 

[adityapm]

Difficult waiting on kindness of strangers. I filled out a questionnaire.

Else I threaten to share my experiments with you all soon. Thanks all

I am laughing here reading your reply.

I have not spent even an hour without thinking about your project.
I am processing all the data and trying to decide on a course of action.
I have to an extent the picture already in my head, am only waiting for this to be justified.
Most chances are it will be ready tonight.

Now for a change, do you have your Moon in Aries in your Astro chart ?
Or is Aries your ascendant ?
Or is Mars sitting in your 1st house or the 6th house or the 10th house ?

Laughing.......

I will be back soon...bye

 

[Sushant Sharma]

I am laughing here reading your reply.

I have not spent even an hour without thinking about your project.
I am processing all the data and trying to decide on a course of action.
I have to an extent the picture already in my head, am only waiting for this to be justified.
Most chances are it will be ready tonight.

Now for a change, do you have your Moon in Aries in your Astro chart ?
Or is Aries your ascendant ?
Or is Mars sitting in your 1st house or the 6th house or the 10th house ?

Laughing.......

I will be back soon...bye

Haha..you are reading me like an open baffle.

I'd share these details too about my moon and Aries but I am afraid you will have feng shui decide whether the ports go on the west side or south side of the speaker cabinet.

On a serious note, I very eagerly await your reply. Many thanks.

 

[adityapm]

Haha..you are reading me like an open baffle.

I'd share these details too about my moon and Aries but I am afraid you will have feng shui decide whether the ports go on the west side or south side of the speaker cabinet.

On a serious note, I very eagerly await your reply. Many thanks.

Before starting, let me tell you this on a serious note, that whether it is feng-shui or any other thing, one can not have a port (means an opening) on a speaker box or house or any other structure for that matter on the west/south side, but only on the east/north side. Never do that.

Now to topic....

First the drivers:

416-8c 2 nos.- Ferrite drivers, same coil/cone as in a 416-8b. Parameters are available So no worries here.

416-8a 2 nos.- Alnico drivers, same coil/cone as in a 416-8b. Parameters are not available, but I have measured values with me.
Fear of weakened magnets resulting in shifted Qts and output efficiency exists. You have mentioned that they came from Heathkit 101 boxes.So the chances are they were not abused.. Meaning less magnetism loss. A 416-8a/b driver if driven at 1+ Amp current for 2/3 hours it will lose nearly 15/20% of its strength in one go.
Do a battery-click-test (2 pencil batteries-3 volts) of all 4 drivers to roughly assess the strength from the.sound.

RCA 4584 drivers 2 nos.- These are for PA application with phenolic diaphragms. The low end is good at around 200Hz, but the top end tops out at 8000. They will need a tweeter for the top end. These are mostly for firing from behind the cinema screens. They can be used for 3 way designs ofcourse

288 drivers 2 nos.- These are one of the most coveted hf drivers in the industry. No issues here. You have mentioned some problems regarding its diaphragms, but they can be procured from the US via ebay. But the manufacturer/supplier GPA (Great Plains Audio Okhlahoma) no more exists. Its owner Bill Hannuck who was catering to the needs of the Altec community since the closure of Altec in 1998, has sold off the complete outfit along with the total component/spare stocks, and it has been bought by some Troy Electronics in Mexico. No spares and services are available anymore. There is also no information about the future activities and address etc. So your source will be only from individual sales on ebay etc. Parameters will not be an issue unless they are very bad. It seems you are already using one. You can switch the drivers and compare the results.

Now the listening space:

The floor foot-print is good. The ceiling height is a bit less at 9.5 ft. to utilize the full floor. There will be the fear of ceiling reflections muddying the sound. The floor can be covered at least near the boxes' front. For this type of room, the box height can not be more than 5 ft.

So, 210/211 is ruled out. their height will reach 8 ft+.

815 - Yes it will work, its height is at 44 inches, and the horn perched at the top will add 15 inches around, but it will also be angled down to focus at 15 ft away. So no problem here. The foot print is at around 3 ft by 3 ft.(actually 33"x34". The horn loads from 75 to 600 aprox., and it is almost bass area. Floor coupling will further lower it down. The sound is very pleasant, very suitable for your choice of music. The parallel sides will of course ring.... but it is at around 100 Hz., and it is good news. If needed, the bottom can be added with a reflex chamber of around 12 inches height to simulate a 210 / A5/7 type of effect to reach around 45 Hz response. Consructing the cab also will be not complicated. Cross over will be simle 2nd order or 12 dboctave

816 - Not recommended for hifi, also single speaker only design.
817 - Not recommended for hifi purpose.
A5/7 - Both are same, except that the A5 uses the professional series 515B/515G series woofers and 288 HF drivers with 511 (or the cellular) horns, whereas the A7 uses 416-8b and 802D HF drivers and both 511 (500Hz) and 811 horns (800Hz). They are called as A7-500 and A7-800 resectively.
This model can be used but it is a single-driver design, very mid-ish, lacks bass, and rings at 244 Hz due to the sawn-off horn with 14 inch depth. The physical size is good at 30 x 24 x 42 and plus the horn height 15 inches more. Looks nice. This one is the most-recognised models of Altec.I have built and used one pair for 6 years, but finally gave it away to a friend. Got tired of the projected sound. Craved for the velvety/caressing soft but loud renderings.
A9 concept - This will be a 30 cu ft (5ft tall x 2 ft deep x 3 ft wide) sealed or reflex type. The horn will sit atop angled down. This will give the smoothest sound, and the simplest to build.The actual dimensions can be modified to make a 4 ft high one.

You think about all this. About crossover matter, do not worry. Let me know what you decide. Your listening level is very low. It should be at around 96 db, meaning you can talk to someone while listening but will not miss the nuances.

Bye for now.........

 

[srinisundar]

Before starting, let me tell you this on a serious note, that whether it is feng-shui or any other thing, one can not have a port (means an opening) on a speaker box or house or any other structure for that matter on the west/south side, but only on the east/north side. Never do that.

Now to topic....

First the drivers:

416-8c 2 nos.- Ferrite drivers, same coil/cone as in a 416-8b. Parameters are available So no worries here.

416-8a 2 nos.- Alnico drivers, same coil/cone as in a 416-8b. Parameters are not available, but I have measured values with me.
Fear of weakened magnets resulting in shifted Qts and output efficiency exists. You have mentioned that they came from Heathkit 101 boxes.So the chances are they were not abused.. Meaning less magnetism loss. A 416-8a/b driver if driven at 1+ Amp current for 2/3 hours it will lose nearly 15/20% of its strength in one go.
Do a battery-click-test (2 pencil batteries-3 volts) of all 4 drivers to roughly assess the strength from the.sound.

RCA 4584 drivers 2 nos.- These are for PA application with phenolic diaphragms. The low end is good at around 200Hz, but the top end tops out at 8000. They will need a tweeter for the top end. These are mostly for firing from behind the cinema screens. They can be used for 3 way designs ofcourse

288 drivers 2 nos.- These are one of the most coveted hf drivers in the industry. No issues here. You have mentioned some problems regarding its diaphragms, but they can be procured from the US via ebay. But the manufacturer/supplier GPA (Great Plains Audio Okhlahoma) no more exists. Its owner Bill Hannuck who was catering to the needs of the Altec community since the closure of Altec in 1998, has sold off the complete outfit along with the total component/spare stocks, and it has been bought by some Troy Electronics in Mexico. No spares and services are available anymore. There is also no information about the future activities and address etc. So your source will be only from individual sales on ebay etc. Parameters will not be an issue unless they are very bad. It seems you are already using one. You can switch the drivers and compare the results.

Now the listening space:

The floor foot-print is good. The ceiling height is a bit less at 9.5 ft. to utilize the full floor. There will be the fear of ceiling reflections muddying the sound. The floor can be covered at least near the boxes' front. For this type of room, the box height can not be more than 5 ft.

So, 210/211 is ruled out. their height will reach 8 ft+.

815 - Yes it will work, its height is at 44 inches, and the horn perched at the top will add 15 inches around, but it will also be angled down to focus at 15 ft away. So no problem here. The foot print is at around 3 ft by 3 ft.(actually 33"x34". The horn loads from 75 to 600 aprox., and it is almost bass area. Floor coupling will further lower it down. The sound is very pleasant, very suitable for your choice of music. The parallel sides will of course ring.... but it is at around 100 Hz., and it is good news. If needed, the bottom can be added with a reflex chamber of around 12 inches height to simulate a 210 / A5/7 type of effect to reach around 45 Hz response. Consructing the cab also will be not complicated. Cross over will be simle 2nd order or 12 dboctave

816 - Not recommended for hifi, also single speaker only design.
817 - Not recommended for hifi purpose.
A5/7 - Both are same, except that the A5 uses the professional series 515B/515G series woofers and 288 HF drivers with 511 (or the cellular) horns, whereas the A7 uses 416-8b and 802D HF drivers and both 511 (500Hz) and 811 horns (800Hz). They are called as A7-500 and A7-800 resectively.
This model can be used but it is a single-driver design, very mid-ish, lacks bass, and rings at 244 Hz due to the sawn-off horn with 14 inch depth. The physical size is good at 30 x 24 x 42 and plus the horn height 15 inches more. Looks nice. This one is the most-recognised models of Altec.I have built and used one pair for 6 years, but finally gave it away to a friend. Got tired of the projected sound. Craved for the velvety/caressing soft but loud renderings.
A9 concept - This will be a 30 cu ft (5ft tall x 2 ft deep x 3 ft wide) sealed or reflex type. The horn will sit atop angled down. This will give the smoothest sound, and the simplest to build.The actual dimensions can be modified to make a 4 ft high one.

You think about all this. About crossover matter, do not worry. Let me know what you decide. Your listening level is very low. It should be at around 96 db, meaning you can talk to someone while listening but will not miss the nuances.

Bye for now.........

I will go later deep into study.. Just browsed a small correction. He has RCA MI95854 drivers not the RCA 4584 as u have mentioned.

The RCA MI9584 and variants were the post war permanent magnet mid/hf drivers of RCA's cinema sound systems. The RCA drivers are arguably some of the best permanant magnet midrange drivers ever produced .They are designed to work from 300-8000hz. and use a phenolic diaphragm. For hifi use a tweeter is mandatory. ( just copied from @Rajiv post but my opinion is also same since i am also using those )

 

[adityapm]

I will go later deep into study.. Just browsed a small correction. He has RCA MI95854 drivers not the RCA 4584 as u have mentioned.

The RCA MI9584 and variants were the post war permanent magnet mid/hf drivers of RCA's cinema sound systems. The RCA drivers are arguably some of the best permanant magnet midrange drivers ever produced .They are designed to work from 300-8000hz. and use a phenolic diaphragm. For hifi use a tweeter is mandatory. ( just copied from @Rajiv post but my opinion is also same since i am also using those )

Yes, just a typo. These phenolic drivers are in the circuit only for the nostalgia sake.

The same also for old alnico drivers. I prefer the ferrites. They are a bit harsh when driven hard, but never lack punch or bite. After all they are rocks. But alnicos are metal. They are very permeable, and the hysteresis curve changes as the current varies. This is the reason why the measured parameters when used do not give the desired results. Parameter measurements are normaly done with very little signal strength, as little as 1 milliwatt. But real use happens always at higher currents.and at that level the parameters have changed. Thats what happens.The trick here is to use a higher current for the TSP measurements, and then it will work when they are plugged in. But driven hard they will not give that bite that one expects. They will somehow prevent clipping, and sound roundish. It is like triodes and pentodes. When driven hard triodes will still keep it smooth but wiill lose the bite, whereas pentodes will show their true nature, a pure current source, and will go on driving hard with bite and punch. Ferrite drivers' TSPs always work alright.
After all we have graduated from alnicos to ferrites, from phenolic to metallic. Once the production techniques were at hand, all became metal diaphragms and higher bandwidths arrived.

Thanks

 

[Sushant Sharma]

Before starting, let me tell you this on a serious note, that whether it is feng-shui or any other thing, one can not have a port (means an opening) on a speaker box or house or any other structure for that matter on the west/south side, but only on the east/north side. Never do that.

Now to topic....

First the drivers:

416-8c 2 nos.- Ferrite drivers, same coil/cone as in a 416-8b. Parameters are available So no worries here.

416-8a 2 nos.- Alnico drivers, same coil/cone as in a 416-8b. Parameters are not available, but I have measured values with me.
Fear of weakened magnets resulting in shifted Qts and output efficiency exists. You have mentioned that they came from Heathkit 101 boxes.So the chances are they were not abused.. Meaning less magnetism loss. A 416-8a/b driver if driven at 1+ Amp current for 2/3 hours it will lose nearly 15/20% of its strength in one go.
Do a battery-click-test (2 pencil batteries-3 volts) of all 4 drivers to roughly assess the strength from the.sound.

RCA 4584 drivers 2 nos.- These are for PA application with phenolic diaphragms. The low end is good at around 200Hz, but the top end tops out at 8000. They will need a tweeter for the top end. These are mostly for firing from behind the cinema screens. They can be used for 3 way designs ofcourse

288 drivers 2 nos.- These are one of the most coveted hf drivers in the industry. No issues here. You have mentioned some problems regarding its diaphragms, but they can be procured from the US via ebay. But the manufacturer/supplier GPA (Great Plains Audio Okhlahoma) no more exists. Its owner Bill Hannuck who was catering to the needs of the Altec community since the closure of Altec in 1998, has sold off the complete outfit along with the total component/spare stocks, and it has been bought by some Troy Electronics in Mexico. No spares and services are available anymore. There is also no information about the future activities and address etc. So your source will be only from individual sales on ebay etc. Parameters will not be an issue unless they are very bad. It seems you are already using one. You can switch the drivers and compare the results.

Now the listening space:

The floor foot-print is good. The ceiling height is a bit less at 9.5 ft. to utilize the full floor. There will be the fear of ceiling reflections muddying the sound. The floor can be covered at least near the boxes' front. For this type of room, the box height can not be more than 5 ft.

So, 210/211 is ruled out. their height will reach 8 ft+.

815 - Yes it will work, its height is at 44 inches, and the horn perched at the top will add 15 inches around, but it will also be angled down to focus at 15 ft away. So no problem here. The foot print is at around 3 ft by 3 ft.(actually 33"x34". The horn loads from 75 to 600 aprox., and it is almost bass area. Floor coupling will further lower it down. The sound is very pleasant, very suitable for your choice of music. The parallel sides will of course ring.... but it is at around 100 Hz., and it is good news. If needed, the bottom can be added with a reflex chamber of around 12 inches height to simulate a 210 / A5/7 type of effect to reach around 45 Hz response. Consructing the cab also will be not complicated. Cross over will be simle 2nd order or 12 dboctave

816 - Not recommended for hifi, also single speaker only design.
817 - Not recommended for hifi purpose.
A5/7 - Both are same, except that the A5 uses the professional series 515B/515G series woofers and 288 HF drivers with 511 (or the cellular) horns, whereas the A7 uses 416-8b and 802D HF drivers and both 511 (500Hz) and 811 horns (800Hz). They are called as A7-500 and A7-800 resectively.
This model can be used but it is a single-driver design, very mid-ish, lacks bass, and rings at 244 Hz due to the sawn-off horn with 14 inch depth. The physical size is good at 30 x 24 x 42 and plus the horn height 15 inches more. Looks nice. This one is the most-recognised models of Altec.I have built and used one pair for 6 years, but finally gave it away to a friend. Got tired of the projected sound. Craved for the velvety/caressing soft but loud renderings.
A9 concept - This will be a 30 cu ft (5ft tall x 2 ft deep x 3 ft wide) sealed or reflex type. The horn will sit atop angled down. This will give the smoothest sound, and the simplest to build.The actual dimensions can be modified to make a 4 ft high one.

You think about all this. About crossover matter, do not worry. Let me know what you decide. Your listening level is very low. It should be at around 96 db, meaning you can talk to someone while listening but will not miss the nuances.

Bye for now.........

Thanks for such a detailed write up Aditya. Wealth of info there. Let me wrap my head around it slowly.

With regards to RCA MI 9584, Victor of Japan branded equivalent is what I have. It's bloody fantastic. Never a harsh note and its like honey. Very easy on the ears. But as pointed out it must be used with a tweeter up top as it goes upto 8000hz (movie soundtracks at the time only went that high up). Most small jazz trio music, vocal focused music and the like, sounds great 2 way. The phenolic diaphragms used are very rounded and just beautiful sounding. I would like to retain them for that.

My 288c have an aftermarket titanium diaphragm which is very detailed can sound a tad sharp and fatiguing at higher volumes only. I must change it to an aluminium diaphragm soon. But my observation within this brief period of using them is that the 288c even with the titanium diaphragm are very exciting and have a large sound. Very enjoyable. The scale of them and the large sound the 288s throw is very nice.

GPA wrote and said 288 diaphragms will be available on their website in January but it hasn't happened. They have the smaller format diaphragms listed on their website.
Now coming to the cabinet. It is narrowed down to an 815 and a concept A9 in my use case.
I am leaning more towards the A9 but would like to reduce the height to 4ft like you have mentioned can be done. But so will other allied measurements i am guessing.
I have a 2ft x1 ft concrete beam hanging down from the ceiling just about 3 to 4 ft away from where my speakers are placed. You think suspect qts and out of spec issues with my drivers will be better overlooked by a sealed A9 cabinet? Plus it helps that they are easier to build.
Another question that comes to my mind is should I worry about internal bracing or partitions etc or just build a bigger box as per the A9 concept spec?