9846 plans wanted

[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.....

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.

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. 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.





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/image...-8b/page04.jpg

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

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

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).

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