9846 plans wanted

[arawak1969]

Searching for a legible set of assembly drawings for the 9846's.
All help is greatly appreciated.
:)

[moldyoldy]

With varying published dimensions for the A, B, and biamped, that's kind of a crapshoot. As a factory-built monitor, plans may have never been released. All I know of is this;
http://www.lansingheritage.org/images/altec/plans/1974-enc-design/page22.jpg

[arawak1969]

I have an old set from my Dad and I guess I will have to get them reproduced.

He had ordered the kit for the biamp model back in the early 70's and all that remains is the plans and the biamps.

[moldyoldy]

arawak1969,
That's some very encouraging news.:bouncy: I've also looked long and hard for these plans. The 9846 was a well-respected design, and still has several devotees, some like me who have all the components just waiting to be installed. If you could scan them you could upload them to this thread on enclosures;

http://audioheritage.org/vbulletin/showthread.php?t=3166

If that isn't possible, I'd gladly pay the postage, do the scanning and upload and return them to you immediately. PM me if you desire.

After lots of page-flipping comparison, it appears that the 1233 plans from AN11 in the library are very close, and could be adapted with the correct dimensions and omitting the ports. Still be better to have the real McCoy, though.

[Art J.]

Hi gang, I will help out if I can but things have been incredibly
busy here and projects are on hold. Besides just the box, the
9846 has that bump out in the front to make the driver offset
exactly a half wave at the 500hz crossover point. More later
if time allows. Art :)

http://webpages.charter.net/artj/9846216.JPG (http://webpages.charter.net/artj/9846216.JPG)

[arawak1969]

Hi gang, I will help out if I can but things have been incredibly
busy here and projects are on hold. Besides just the box, the
9846 has that bump out in the front to make the driver offset
exactly a half wave at the 500hz crossover point. More later
if time allows. Art :)

http://webpages.charter.net/artj/9846216.JPG (http://webpages.charter.net/artj/9846216.JPG)
Two quick questions:
1. What are the differences between the 802-8A and the 802-8g drivers?
2. Why do you have your 9846's on a platform?

Thanks.:)

[arawak1969]

Do I need the attenuator if I am biamping?
Can I substitute a newer driver (802-8g) for the original and how will it affect the sound? :D

[Art J.]

1. What are the differences between the 802-8A and the 802-8g drivers?
Others would have to help you there. I have no issues with the 8a's

2. Why do you have your 9846's on a platform?
That's the way I got them.
They were sent to a cabinet maker for the stands and finish to match the
auditorium stage they were displayed on. I prefer them up anyway.

Do I need the attenuator if I am biamping?
Its up to you. I still prefer using it for near-field listening.

:barf:

[moldyoldy]

Two quick questions:
1. What are the differences between the 802-8A and the 802-8g drivers?

Here lately, about $150 each!;)

The only signifigant difference is the phase plug, 8as had a metal annular ring, 8gs had a plastic radial called Tangerine. While the Tangerines are considered superior, this doesn't mean there's anything wrong with the others. The original stock diaphragms differed naturally, due to the time produced, but are fully interchangeable with any other 1" Altec 'fram with the following exception; 8as that still have original rear covers and screw-terminals on the 'fram are "old-style", so to install the later (and current) new diaphragms with spade terminals, you'll need to either adapt or update to new-style rear covers/wiring (about $20 at GPA).

Other than original diaphragms, the 808 series fits the same description, As with annular plgs, Bs with Tangerines. Same motor assy.

[arawak1969]

I am currently running a pair of Altec Santiago's with Altec 771 biamps.
What do I need to do to convert my 808 drivers to 802's and can I then run them at the 500hz crossover like the 9846's?
Can I add a material such as Dynamat to dampen the 811 horns and reduce the ringing?
I added a graphic eq over the last week and have been very happy with the improvement around the attenuator frequency of 1Khz. I bumped the LF output up 6db on the biamps and the system is starting to sound a lot better.

I will be scanning the plans over the next couple of weeks and will let you know once they become available.
Cheers

[moldyoldy]

With 808s vs 802s, the diaphragm you use is the difference, 802s use aluminum, 808s originally used Symbioteks, which were replaced by Pascalite. Although the old Symbioteks gave up some response for power handling, the new Pascalites are a big improvement, so the difference now is largely subjective and small.

Either 808s or 802s can be run at 500Hz, but only on a horn that will handle it, and not the 811, which is an 800Hz horn. Yes, you can add external damping to the horn if you feel it's needed. If it's only an issue when you thump them or read user forums, just stop thumping them and ignore the forums.....;)

+6dB's a lot of LF boost, especially for a 771 biamp. In stock configuration, they should play pretty darn flat without EQ. It's possible you may need some caps replaced in the 771s, or maybe relocating the speakers to suit the room modes better, which I'd try first. It's generally considered better practice to attenuate the objectionably louder bandwidth to acheive tonal balance than to boost the other, for less distortion and greater wideband SPL. This is one reason why most Altec EQs were cut-only.

[Art J.]

Searching for a legible set of assembly drawings for the 9846's......................................
I will be scanning the plans over the next couple of weeks and will let you know once they become available.
Cheers

Thanks for doing that. Get the best scan you can and I can touch them up in
"Photo Shop" if needed.
Ive done that before for Model 19 plans.

Before
http://home.earthlink.net/~jmarkwart/id13.html (http://home.earthlink.net/~jmarkwart/id13.html)

After
http://home.earthlink.net/~jmarkwart/id14.html (http://home.earthlink.net/~jmarkwart/id14.html)

[arawak1969]

With 808s vs 802s, the diaphragm you use is the difference, 802s use aluminum, 808s originally used Symbioteks, which were replaced by Pascalite. Although the old Symbioteks gave up some response for power handling, the new Pascalites are a big improvement, so the difference now is largely subjective and small.

Either 808s or 802s can be run at 500Hz, but only on a horn that will handle it, and not the 811, which is an 800Hz horn. Yes, you can add external damping to the horn if you feel it's needed. If it's only an issue when you thump them or read user forums, just stop thumping them and ignore the forums.....;)

+6dB's a lot of LF boost, especially for a 771 biamp. In stock configuration, they should play pretty darn flat without EQ. It's possible you may need some caps replaced in the 771s, or maybe relocating the speakers to suit the room modes better, which I'd try first. It's generally considered better practice to attenuate the objectionably louder bandwidth to acheive tonal balance than to boost the other, for less distortion and greater wideband SPL. This is one reason why most Altec EQs were cut-only.
What are the influences that placement will have on the sound? Room is 16'x 30' and speakers are placed in the corners on one 16' side:dont-know .

[moldyoldy]

What are the influences that placement will have on the sound? Room is 16'x 30' and speakers are placed in the corners on one 16' side:dont-know .

Whoooeee! Guess I left myself wide open for that one......

In short, A WHOLE BUNCH.

Room acoustics is a subject you can spend several years to get a degree in, and what I could tell you wouldn't get you past the first week.

The most noticeable effect is usually in the deep bass. Corner placement generally increases bass, but not always. For high frequencies, minimizing sources of early reflections is important, and where you sit and listen will effect things too. You can study, buy test equipment, perform computer analyses, and go broke on room treatments. Or you can simply experiment, observing each change long enough to know if it's better, worse, or just the same. Take notes. One almost certainty with your horns is you'll need to have them near the same height off the floor as your ears (in your listening spot), and both toe'd in enough to aim right at you. They spread the midrange pretty well, but the highs are focused, sort of like a flashlight beam. When experimenting, set your tone controls on the amp flat, no boost or cut, it'll be easier to notice changes. An audio test CD or LP would be a worthwhile investment to get started. Parts Express has some.

If you wanna study, here's a start (there ain't no end);;)

http://en.wikipedia.org/wiki/Room_acoustics

(add/edit; If you end up building the 9846s, you'll need 511 horns)

[arawak1969]

Whoooeee! Guess I left myself wide open for that one......

In short, A WHOLE BUNCH.

Room acoustics is a subject you can spend several years to get a degree in, and what I could tell you wouldn't get you past the first week.

The most noticeable effect is usually in the deep bass. Corner placement generally increases bass, but not always. For high frequencies, minimizing sources of early reflections is important, and where you sit and listen will effect things too. You can study, buy test equipment, perform computer analyses, and go broke on room treatments. Or you can simply experiment, observing each change long enough to know if it's better, worse, or just the same. Take notes. One almost certainty with your horns is you'll need to have them near the same height off the floor as your ears (in your listening spot), and both toe'd in enough to aim right at you. They spread the midrange pretty well, but the highs are focused, sort of like a flashlight beam. When experimenting, set your tone controls on the amp flat, no boost or cut, it'll be easier to notice changes. An audio test CD or LP would be a worthwhile investment to get started. Parts Express has some.

If you wanna study, here's a start (there ain't no end);;)

http://en.wikipedia.org/wiki/Room_acoustics

(add/edit; If you end up building the 9846s, you'll need 511 horns)

Well I am doing the 9846 boxes and am looking for the 511's on ebay.
I am also keeping and eye out for a set of 411 woofers and 802-8g drivers. The attenuator is the one thing I have not seen and wonder if I will really need.
I am planning on scanning the plans that I have here next Wednesday and picking up the wood. I will be using marine grade ply as listed on the plans and staining to match my furniture. I will probably do some pedestals at the same time to get them to the same height as my listening chair.
Anyone have the correct attenutaors out there?

[Art J.]

The attenuator is the one thing I have not seen and wonder if I will really need.

You could do fine without it. It takes the shout out of the 511 in near field listening
and also gives you a bit of extended hi range by attenuating the lower range of the horn.
You could also build your own by this diagram.

http://webpages.charter.net/artj/Altec3090430923.jpg (http://webpages.charter.net/artj/Altec3090430923.jpg)

[moldyoldy]

Since 411s aren't quite as efficient as most other Altec 15"s, I consider the attenuator network essential to blend the medium eff woofer with the high eff horn. (Apparently, Altec engineers did too). Additionally, it provides the correct shelving to allow the 802/511 to compensate for its' normally falling HF response.

The attenuator networks don't hit eBay too often, but fortuneately are easy enough to build, and our good buddy Art J has kindly provided the necessary info.

The 30923 is for biamp models, the 30904 is for use with an N501-8A crossover.

[moldyoldy]

Great minds must think alike Art!;)

[Art J.]

We have collided at the same time before. Always good to see you.......

How about going all out for a pair of 9848's

http://www.lansingheritage.org/html/altec/specs/pro-speakers/9848.htm (http://www.lansingheritage.org/html/altec/specs/pro-speakers/9848.htm)

[moldyoldy]

We have collided at the same time before. Always good to see you.......

How about going all out for a pair of 9848's

http://www.lansingheritage.org/html/altec/specs/pro-speakers/9848.htm (http://www.lansingheritage.org/html/altec/specs/pro-speakers/9848.htm)
Definitely a worthy aspiration, Art, but I suspect by the time I came up with a quad of 16 ohm 411s I wouldn't have much time left to enjoy them!

[arawak1969]

:blah:
Since 411s aren't quite as efficient as most other Altec 15"s, I consider the attenuator network essential to blend the medium eff woofer with the high eff horn. (Apparently, Altec engineers did too). Additionally, it provides the correct shelving to allow the 802/511 to compensate for its' normally falling HF response.

The attenuator networks don't hit eBay too often, but fortuneately are easy enough to build, and our good buddy Art J has kindly provided the necessary info.

The 30923 is for biamp models, the 30904 is for use with an N501-8A crossover.
Alrighty then.
Did I mess up by running the HF from the Santiago's direct to the HF side of the biamp?

[moldyoldy]

:blah:
Alrighty then.
Did I mess up by running the HF from the Santiago's direct to the HF side of the biamp?

Not really, but by doing so you lose the attenuation and shelving the network provides. This could explain why you felt the need for the +6dB bass boost though. I think the attenuation might be needed less in an 800Hz app like the Santiago than in 500Hz systems, simply because the HF driver carries less of the bandwidth load. I do think you might prefer the performance if you connected the HF drivers to the network as shown, and hook the woofers directly to the biamp out. Otherwise, you've already got a pair of att networks for your upcoming 9846s.

Now I'm curious about your setup. Straight Santiagos (878A or B) came with an N801-8A network and the 30904 att/eq. The factory biamp version had a 770 biamp and the 30923 network, but were tagged as 2878A or B. In either version, the "A"s used 413s and the "B"s used 411s.

[arawak1969]

Not really, but by doing so you lose the attenuation and shelving the network provides. This could explain why you felt the need for the +6dB bass boost though. I think the attenuation might be needed less in an 800Hz app like the Santiago than in 500Hz systems, simply because the HF driver carries less of the bandwidth load. I do think you might prefer the performance if you connected the HF drivers to the network as shown, and hook the woofers directly to the biamp out. Otherwise, you've already got a pair of att networks for your upcoming 9846s.

Now I'm curious about your setup. Straight Santiagos (878A or B) came with an N801-8A network and the 30904 att/eq. The factory biamp version had a 770 biamp and the 30923 network, but were tagged as 2878A or B. In either version, the "A"s used 413s and the "B"s used 411s.
I have the 878B model with the 411 woofer and 811 horn. I do not remember which driver is on the horn.

[moldyoldy]

An 878B would have an 806-8A driver, which is slightly smaller than 802s or 808s, and less suitable for 500Hz XOs.

[arawak1969]

An 878B would have an 806-8A driver, which is slightly smaller than 802s or 808s, and less suitable for 500Hz XOs.
Well I will just have to wait and get the 802/808 driver, 511 horn and another set of 411's. I think I will just build the boxes while I search ebay for the items.
I don't want to rip the 878's apart since they are all original and they sound pretty good as-is.

Do you think Kinkos would be okay to scan the plans?

[moldyoldy]

Yeah, Kinkos can scan full-size blueprint pages. Check pricing first, B&W or greyscale should be much cheaper than color for a large doc, and is all that's needed.

[arawak1969]

Yeah, Kinkos can scan full-size blueprint pages. Check pricing first, B&W or greyscale should be much cheaper than color for a large doc, and is all that's needed.

Happy turkey day.Hope y'all got 'stuffed'.
Well Professor, have you had a chance to really look at the drawings?

I have been hunting the parts and should have something in the works by next w/e for the 411's.
Is there a quality differnce in the components for the Attenuators that I should consider and if so which supplier should I call?

[X_X]

Back when those Altec studio monitors where designed- there were no T/S parameters. Thus, the only mystical mathmatical formula the builders could utilize was the Golden Ratio (http://en.wikipedia.org/wiki/Golden_ratio).

The Golden Ratio states that for any two values (in this case the depth and width of the cabinets) summed with respect to the larger measurement= the ratio of the two measurements (dividing the larger by the smaller)= roughly 1.6

Take an Altec 9844 cabinet for example. The rough measurements are 16X24X31.

(24+16)/24=24/16=(~)1.6

Doing the math reveals that the Golden Ratio holds (fairly) true, such is the case for many of the older Altec monitors. For their day, the engineers knew what they were doing as that formula held a lot of unexplanable "rights" and seemed to work in favor of most things.

However- T/S changed all of that hocus pocus and backed it up with real logic. What may have been a winning formula for building bridges and buildings did NOT always work optimally for speakers.

Most of the Altec LF drivers have their T/S parameters displayed on the Altec site. Here is a link to that: http://alteclansingunofficial.nlenet.net/Thiele-Small.html (http://alteclansingunofficial.nlenet.net/Thiele-Small.html)

Since these values more accurately respresent the ideal in speaker enclosure design- I would choose them over factory Altec specs.

The displacement value the horns impose is difficult to determine; I wouldn't even put them in the same cabinet. I would also go active on the crossovers. A lot has changed since these monitors were originally built and why not take advantage of those things? There is no question- the drivers are very good even by today's standards but I would build to help maximize that potential.

Nate.

[moldyoldy]

Arawak;

I put on my best lonely hermit act, and got invited to two turkey dinners, and even scored leftovers from both. Spent most of the weekend sleeping it off.

I'm working the drawings over in Photoshop, trying to make them as nice as I can before uploading. Actually, about all that's needed is filling in the bits and pieces that must have been too faded on the original to scan, mainly in the text. Shouldn't take too long though.

Nate,

Thiele's primary work (A.N. Thiele, "Loudspeakers in vented boxes", (reprint) proc. IREE (Australia), Vol.22) was released in Aug.,1961, long before the 9846 and several other monitor models were designed, and R.H. Small's "Vented box loudspeaker systems Part II: Large signal analysis", AES Journal, Vol. 21, No. 6 was released August, 1973, the first year of production. The use by Altec engineers of T-S vented box strategy in the design of the 9846 is highly unlikely even if available though, as the 9846 is a SEALED BOX.

The T-S parameters in the list you refer to for Altec drivers that were made before the existence of such parameters were DERIVED from the old basic measured data, which suggests to me they really did have all the data they needed. Just because pre-T-S engineers didn't have today's CAD ability or box-design freeware doesn't mean they lacked ANY of the essentials for proper system design, nor does it mean that modern design technique is automatically superior.

The displacement of the horn is no issue, as it's listed with several others in the 1968 (pre-T-S) enclosure guide. I can't imagine why they'd include that data way back then.....:blink:

As to mounting the horn inside the enclosure as designed, I'll make note that you wouldn't do it, and proceed accordingly.

None of this really means squat to me though, because my decision to build this system came from many hours of listening to a pair, not because they're today's "must-have" on some forum. One of the best-sounding, poorly-designed systems I ever heard. Also, I HAVE run the numbers, and the 9846 turns out to be the optimal system for the 411, when you consider the greater distortion inherent with a vented (4 cu ft larger) enclosure against the little usable gain in sensitivity. Guess they just got lucky. One thing they DID have back then, was the ability to measure the performance of all those poorly-engineered systems. No matter how the design was arrived at, the fact remains that it's a very good one, and exceeds the vast majority of 2-ways available today;

[moldyoldy]

...snip...Is there a quality differnce in the components for the Attenuators that I should consider and if so which supplier should I call?

For the 30904 Att/EQ networks, here's a list of equivalents from parts express, and only lacks terminal strips and wire (qty for 2 assys). Since PE didn't have the 5 ohm 15W resistors, I subbed for 2 parallel 10 ohm 10W. If you're building the 30923s for biamping, omit the first 2 line items. These pts are near-equivalents, so you're free to upgrade to the guilt/doubt/price breakpoint if you're so inclined.;)

Part Number Description Qty. Price Ext. Price

004-10 DAYTON DNR-10 10 OHM 10W NON-INDUCTIVE .. 4 ea $3.92
027-434 DAYTON DMPC-18 18uF-250V POLYPROPYLENE ..2 ea $9.30
004-4 DAYTON DNR-4.0 4 OHM 10W NON-INDUCTIVE .. 4 ea $3.92
027-427 DAYTON DMPC-6.2 6.2uF-250V POLYPROPYLEN ..2 ea $4.30
004-6.5 DAYTON DNR-6.5 6.5 OHM 10W NON-INDUCTIV ..2 ea $2.50
262-079 END PLATE FOR R1197 HEAT SINK BOX .. 2 ea $3.70

Subtotal: $26.22

[X_X]

The use by Altec engineers of T-S vented box strategy in the design of the 9846 is highly unlikely even if available though, as the 9846 is a SEALED BOX.

Lots of attitude on this site- not unlike a pair of JBL speakers ;)

Moldyoldy,

I was not making the arguement that T/S did not exist prior to the 9846's construction- just that Altec engineers seemed to completely side step the utilization of them. They used no T/S parameters in building the 9844- a VENTED BOX. I provided a link to the Altec T/S parameters, so what are you driving at?

Building with T/S, Golden Ratio, or what have you need not be mutually exclusive providing certain variables are constrained. Such can be stated for this notion of "old" engineering and it's opposite(?) "new" engineering. Such humor. Again, the two are not "one or the other". Great things came from "old" engineering and great things come from new engineering. I was merely suggesting the utilization of what we have available today vs what they had available then.


Just because pre-T-S engineers didn't have today's CAD ability or box-design freeware doesn't mean they lacked ANY of the essentials for proper system design, nor does it mean that modern design technique is automatically superior.

Ok.
I guess it depends on what you think qualifies as a 'proper system design'.

...some things are superior today, imo:

Materials, testing, tools, hardware, software, and a more demanding market are just a few of the things that come to mind. Yet I do agree with what you are saying for the most part.



The displacement of the horn is no issue, as it's listed with several others in the 1968 (pre-T-S) enclosure guide.

I didn't know that. Thank you.


I can't imagine why they'd include that data way back then.....:blink:

As to mounting the horn inside the enclosure as designed, I'll make note that you wouldn't do it, and proceed accordingly.

You were clearly being rude, here. I forgot to mention the other place you can stick the horn, but you have stated you prefer to mount them. So...mount them.


One of the best-sounding, poorly-designed systems I ever heard. Guess they just got lucky.

Yes, perhaps they did get lucky with the 9846! I know they weren't so lucky with other speakers...



One thing they DID have back then, was the ability to measure the performance of all those poorly-engineered systems.


You consider the cabinets to be well made by any standard? Heath took many Altec drivers and delivered a vastly superior sounding end product, imo.



No matter how the design was arrived at, the fact remains that it's a very good one, and exceeds the vast majority of 2-ways available today;

No one debated that. Here are a few quotes from my previous post:


There is no question- the drivers are very good even by today's standards. For their day, the engineers knew what they were doing.


For the record- it was not my intention to throw down the gauntlet. I made suggestions and shared my opinion. I thought that's what a public forum is all about..no?

[Hoerninger]

Back when those Altec studio monitors where designed- there were no T/S parameters. Thus, the only mystical mathmatical formula the builders could utilize was the Golden Ratio (http://en.wikipedia.org/wiki/Golden_ratio).

That's not true. Electroacoustical problems can be calculated for long. Reinventing the wheel does not mean that there wasn't any before. In the attached image you see part of the calculation of a bass reflex enclosure done 1952. Don't bother the articel is in german. It's an example and I never went through it..

Thiele Small Parameter are a set of parameters which can far more easily be measured than electroacoustic parameters and are easy to handle.

When you are using SPICE for modelling a speaker, this can be combined with any deviding network, you are using the "old" parameters, But you have to translate them first into electrical parts.

Today we can easily use a computer. In former days engineers could handle a set of equations with about 20 variables. But a skilled engineer needed two days for it. Today it can be done in a second (after the data input ).
____________
Peter

[X_X]

That's not true. Electroacoustical problems can be calculated for long. Reinventing the wheel does not mean that there wasn't any before. In the attached image you see part of the calculation of a bass reflex enclosure done 1952. Don't bother the articel is in german. It's an example and I never went through it..

Thiele Small Parameter are a set of parameters which can far more easily be measured than electroacoustic parameters and are easy to handle.

When you are using SPICE for modelling a speaker, this can be combined with any deviding network, you are using the "old" parameters, But you have to translate them first into electrical parts.

Today we can easily use a computer. In former days engineers could handle a set of equations with about 20 variables. But a skilled engineer needed two days for it. Today it can be done in a second (after the data input ).
____________
Peter



Peter,

Thanks for the information- very interesting! I wish I could read it, though. :(

Was there a standard method for acquiring all of those electroacoustic parameters, or was it unique among different companies? If there were no standards for extracting those values- it would still be a "rough" science, though. Yet, even the way labs measure certain aspects of a driver are greatly varied today. I guess not much has changed when you really think about it...

Nice way of putting it. Thanks!

Nate.

[Ian Mackenzie]

Something that may be of interest is an old publication about all the Altec monitors and it was Red cover..by Davis and Bradman?

Anyway all the actual theory of the tunings is in there.The book is an excellent read, I think Mr Widget and perhaps some other member s have a copy.

Another point of interest is that after T/L arrived a number of the Altec monitors were re tuned according the T/L and Benson's later work. I actually met a guy in Melbourne who was partner in a store called Sound City, Vasey Stocks who was involved in some of the re tuning apparently (late 70's)

A final point, one of our members, Cyclotronguy (Kent) has wealth of knowledge on getting the best out of some of these old Altec systems. I heard his own diy Altecs (4560 modified) while in the USA and I was mighty impessed. You may wish to pm Kent.

I agree that Altec really had the big two ways by the ball's back then.

Its really nice to see some of the Altec systems on the forums!:)

Ian

[moldyoldy]

For the record- it was not my intention to throw down the gauntlet...

Nor mine.

Originally Posted by X_X;13588 "I made suggestions and shared my opinion. I thought that's what a public forum is all about..no?"

It certainly is, and there are many threads here where those suggestions and opinions would be very appropriate. This thread has been about one particular system (9846) and the gathering of construction-related details for it. At least one other participant and myself have expressed our intent to build them. There was never a question of 'should we build them', that decision was made long ago and on hold pending the details.

I largely agree with your assertions, but I got ruffled when I felt you lumped the system under discussion and all old Altec monitors into one outdated group that has generally been left in the dust. If you know of any specific issues inherent to the 9846, by all means let's disscuss them. If not, at least you'll know why I sizzled.

Peace.

[X_X]

Nor mine.

Originally Posted by X_X;13588 "I made suggestions and shared my opinion. I thought that's what a public forum is all about..no?"

I largely agree with your assertions, but I got ruffled when I felt you lumped the system under discussion and all old Altec monitors into one outdated group that has generally been left in the dust. If you know of any specific issues inherent to the 9846, by all means let's disscuss them. If not, at least you'll know why I sizzled.

Peace.

Moldy,

Understood. There is a pair of Altec 2way monitors at my house right now and my guests are often treated to a big surprise when they hear the old grey geese fire up! I really have few gripes about "most" of the Altec 2way monitors. I own a pair myself and they are very impressive- by any standard. I often get focused on sqeezing that last bit of juice a system can bear, but you are right about the quality of the product. It's definately there. They are damn good. I've not heard a pair of 9846's, but perhaps they are even more pleasing than my own. Maybe I should have prefaced my first post by saying all this? I do have a soft spot for old Altec- that's why I ended up in this thread! ;)

I do find the factory networks are hard to duplicate- even with the same value components. Something in the inductors?? I could not get a decent on-axis response since rebuilding the old ones. I used the exact same values but the sound changed for the worse in some ways.:o: Frustrated, I scratched the old topology and rebuilt them again using a standard 2nd order Butterworth at a point of 1200Hz. This was not too far off from what was in them, but I made a change. I used air core inductors. I thought perhaps this was to blame for my poor sound.(?) Well, the sound was good but the ability for the sound to be focused into one area for critical listening was lost. I was told this was called "beaming"? Are you familiar with these things happening? Well, This prompted me to go active and it was a real treat in doing so. I am still amazed at how good those old horns can sound without any passive attenuation. :D





Ian,

I would be most interested in finding out more about the works you mentioned. That does sound like an informative read. I feel some of the early Altecs have an undeserved reputation based on inadequte tunings. The drivers can really deliver when properly tuned! I also find some of the Altecs are limited in power ONLY because of enclosure/tuning colorations. Like I said- the drivers are up to the task when given the chance to sing.


I won't paint on this thread anymore. I look forward to seeing your 9846 projects!! Best of luck. :)

Peace to you, too.

Nathan.

[arawak1969]

[quote=moldyoldy;135868]For the 30904 Att/EQ networks,
Thank you kind sir.
I have a set of 411's heading my way shortly and horns/drivers we spoke of to follow soon after. If I get anxious I my pull the ones I have here but do not anticpate having to. I will get a local electronics store here to try to help me with the Att's.
Glad to hear the hermit act still works. If you are ever around N Ga you are always welcome. One of my Biamps has started to hum a bit so I will have to swap it out with my spare and run it in for them to look over.
Are you going to biamp your's?

[arawak1969]

I just saw this in the archive and it does not show the 30923 as part of the kit.
http://www.lansingheritage.org/images/altec/specs/pro-systems/9846-8b/page04.jpg:blink:


Since 411s aren't quite as efficient as most other Altec 15"s, I consider the attenuator network essential to blend the medium eff woofer with the high eff horn. (Apparently, Altec engineers did too). Additionally, it provides the correct shelving to allow the 802/511 to compensate for its' normally falling HF response.

The attenuator networks don't hit eBay too often, but fortuneately are easy enough to build, and our good buddy Art J has kindly provided the necessary info.

The 30923 is for biamp models, the 30904 is for use with an N501-8A crossover.

[Art J.]

I just saw this in the archive and it does not show the 30923 as part of the kit

Hello Arawak, we have found errors and omissions in the Altec literature before.
The best source has been the driver reference guide where it shows the 30923.

http://www.lansingheritage.org/images/altec/reference/1975-drivers/page11.jpg (http://www.lansingheritage.org/images/altec/reference/1975-drivers/page11.jpg)

Another example of an error is the 9846-8a that shows the 30923 but actually uses
the 30904 as shown in the guide.

http://www.lansingheritage.org/images/altec/specs/pro-systems/9846-8a/page03.jpg (http://www.lansingheritage.org/images/altec/specs/pro-systems/9846-8a/page03.jpg)

Did you mail the plans to Moldy? Keep me posted on the progress. Art

:)

[moldyoldy]

Art, sure seems like we're in a parallel universe sometimes, same thing to say at the same time again. I just brought the data you linked, instead (below).:p

As many errors in the catalogs that we've uncovered, I've still not found any in the '75 Product reference. I always wanted to get it all into a spreadsheet to allow search and regroup, but I type with one finger, and haven't been that bored yet. I've tried to OCR it 3 different ways with little success.

Funny, the -8A catalog lists the network though...as far as I know, it follows the 411 anytime it's used with a HE compression horn in any application, but wasn't needed with anything besides a 411 because it was the only mid-efficiency 15" in the lineup at the time.

Just noticed in the reference, the early model lists a different cab part number. Might explain some of the varied dimensions in the lit.

Yeah, I've got the plans, and started some Photoshop cleanup, but got sidetracked and haven't finished. Still have far too many projects going at once, but I kinda like it that way. If you wanna play with it too, I'll send a copy of the original. The main page must have been really faded, and I haven't been able to easily pull it out from ghosts. Maybe you've got some other tricks I don't know.

Since I've got the parts for passive, and two other active projects have all my XOs and Amps tied up (active 4-ways gobble the gear pretty quick), I'll run what I brung for now. I've never owned any of the Altec biamps, but I've heard several say a good cap job is a requisite, and if you've got new hum, I wouldn't wait too long.

[arawak1969]

The woofers came in today and I will have to send them out to Bill for repair.
$ 60 apiece plus shipping. Not bad.
The horns are due in hopefully before Xmas.
The wife is heading out of town for twoo weeks on business so I have had to shut down all extra activities till she returns.
I was calling around yesterday for the marine grade plywood and I was told by Lowes and Home Depot that they do not carry it anymore but carry regular finished ply.
I had thought about just using MDF and it may just come down to that.
Later

[kilohertz]

Just wondering if anyone found or scanned the plans and posted them somewhere. Let us know how the project turned out. Cheers Paul