Altec MLTL with Model 19 drivers

[ejfud]

Lance, have you ever seen this guide rail system?

http://www.eurekazone.com/

I used it for a long time before the German tool showed up and it works real slick. I still use their table to do most of my cutting on.

 

[diamondsouled]

What are you planning on using for damping material? In cabinets that size a person would go broke if they bought black hole.

I used to like the 4' x 8' paper backed sheet fiberglass stuff they sold that was around an inch thick.

Cheers

Lar

 

[westend]

Lance, have you ever seen this guide rail system?

http://www.eurekazone.com/

I used it for a long time before the German tool showed up and it works real slick. I still use their table to do most of my cutting on.

That is pretty neat stuff. They seemed to have given the whole system a lot of thought.
At some point I may just break down and get the Festool system. I don't need a lot of push to overcome the balance to buy another tool. :yes:

What are you planning on using for damping material? In cabinets that size a person would go broke if they bought black hole.

I used to like the 4' x 8' paper backed sheet fiberglass stuff they sold that was around an inch thick.

Cheers

Lar

Ah, dampening material. I haven't quite narrowed that down, somewhere between lambs wool and R-13, at this point. :scratch2:
I know there have been a few guys that used fiberglass sheets, OC 703 maybe? Found this stuff while browsing around Tempmat.

Got all the panels cut and it is one big stack of goods. If the speaker thing doesn't work out, I bet these would make a Lance size shipping container and that would be headed South. I hate Winter:sigh:.

 

[diamondsouled]

"I hate Winter"

Isn't it spring yet :scratch2:

Been snowing here off and on for the last few days. We were in a full melt last week but an arctic high moved in and we're back into winter weather again, enough already!!!!

That stuff looks interesting. On cabinets that size I generally do the back and two sides. Finding a balance between over and under stuffing can be fun.

There's a handy dandy bit of info here on port tuning:

http://www.lansingheritage.org/html/altec/plans/1974-enc-manual.htm

Even has the graph paper you'll need. :thmbsp:

Cheers

Lar

 

[westend]

Thanks for the link, Lar. I had read that series on enclosure building from Altec Lansing awhile back. It is all good stuff.

The designer of this enclosure and I are still collaborating on the details of the build and he is like one of those professors I had in college that are learned to the point of being "The Source".
In this case, he has particular requirements as to the stuffing and bracing of the line (since this is a transmission line). He has me calculating dimensions from special constants and using Golden Mean ratios. A lot of this is beyond my scope but when he stated that he started using Altec drivers and transmission line design some 42 years ago after a visit to the Altec factory, I just do what he says. I'm considering his tutelage a rare stroke of luck, finding a guy this knowledgeable that is willing to spare his time to design and consult throughout the build. It's like trying to modify your Mustang and having Carroll Shelby along for help.

 

[audiozaz]

Thanks for the link, Lar. I had read that series on enclosure building from Altec Lansing awhile back. It is all good stuff.

The designer of this enclosure and I are still collaborating on the details of the build and he is like one of those professors I had in college that are learned to the point of being "The Source".
In this case, he has particular requirements as to the stuffing and bracing of the line (since this is a transmission line). He has me calculating dimensions from special constants and using Golden Mean ratios. A lot of this is beyond my scope but when he stated that he started using Altec drivers and transmission line design some 42 years ago after a visit to the Altec factory, I just do what he says. I'm considering his tutelage a rare stroke of luck, finding a guy this knowledgeable that is willing to spare his time to design and consult throughout the build. It's like trying to modify your Mustang and having Carroll Shelby along for help.

If we're talking about the same GM, which I think we are, he is a damn fine individual, who helped me out on a number of occasion with various stuff.

Coming along nicely, keep it up!

az

 

[diamondsouled]

Nothing like having a hands on tutor/mentor. :thmbsp:

I purchased an original copy of that Altec Speaker Design book back in 1974. I used their Valencia design; to fit it into one sheet of Red Oak ply I had to leave out the front overhang. Still they turned out nice even though my 'carpenter' friend helped out. When I noticed that one of the cuts he had made was 3/32"s out he said: "not to worry, it will all come together with the glue and screws, it didn't. Ever since then I've done all my own cutting .

Funny thing about tuning the Valencias. They have ducted ports and I started out with the full length but had to cut them down more than half before the cabinet tuned. I was fooling around one day and pulled the ducts out altogether and gave a listen. To my ears the cabinets sounded even better, go figure.

Cheers

Lar

 

[shawnra]

Thanks for the link, Lar. I had read that series on enclosure building from Altec Lansing awhile back. It is all good stuff.

The designer of this enclosure and I are still collaborating on the details of the build and he is like one of those professors I had in college that are learned to the point of being "The Source".
In this case, he has particular requirements as to the stuffing and bracing of the line (since this is a transmission line). He has me calculating dimensions from special constants and using Golden Mean ratios. A lot of this is beyond my scope but when he stated that he started using Altec drivers and transmission line design some 42 years ago after a visit to the Altec factory, I just do what he says. I'm considering his tutelage a rare stroke of luck, finding a guy this knowledgeable that is willing to spare his time to design and consult throughout the build. It's like trying to modify your Mustang and having Carroll Shelby along for help.

the golden means ratio is very important to adhere to. factors to 1.618 and has the least amount of resonance. Honestly I usually just use it to calculate the enclosure that will affect midrange because that seems where it is most critical and makes the most sense. In this case the main enclosure produces a lot of midrange so I can see why your guru wants to use it. For purely bass enclosures I've found it to be less effective then just designing what you can and using intelligent bracing techniques. Is he going to adhere to this principle all the way down the Transmission Line? Or maybe just going to apply it to the back chamber of the Altec as it enters the line?

 

[westend]

Here's the deal on the cabinet tuning and how it relates to the Golden ratio: not at all, really.
The cabinet is an MLTL so the alignment involves quarter-wave theory, Martin King's software modeling, and the wealth of experience of the designer. The positioning of anything in the interior (like braces) affects the dissipation of sound waves produced by the back wave of the woofer so special considerations are taken to not interfere with this pipe effect. The Golden ratio comes into play for positioning the braces on the panels, their size, and the placement of the "window pane" braces that will run the vertical length of the cabinet. I have already been admonished not to use cleats in the corners as this will also lead to some sort of auditory calamity.

My brain interprets some of this as "voodoo" and some of it I understand. The easiest position for me is to just do as I'm told. I have a lot of faith in the designer.

 

[Doc Zinger]

Will be looking for the in progress pics to see the bracing layout, maybe this thread will sprout some new speakers like the F 5 amp one did.

Had a good grin when someone from Minnesota says they hate winters, about like someone out here in Seattle saying they hate rain, although sometimes I do, most likely the same as you and winters. My Dad grew up in SW Minn during the '20-'30s when they had some real serious winters left the state because of it and ended up in Wyoming, go figure that one out!

 

[westend]

Doc, this is not exactly a sprout from the F5 but I had anticipated using the Altec driver combination before I built my first F5. I will have one F5 on the 416 and one on the 802 and the Heil AMT. I am hoping that will work out. The AMT might take a back seat for a bit until I can implement it correctly.

As for the hatin' on the winter, this one has been longer and worse than any recent ones, we're at #5 in the rankings, now and a couple more inches will get us to #4. I know other places in the US have greater totals but the problem here is that when it snows in November, the White Plague stays until March. This year we are experiencing five months of winter, I don't think penguins or polar bears have it that bad. I still have 3' drifts at the end of the driveway.

 

[shawnra]

I don't even remotely understand how you would begin to formulate for brace placement to adhere to the golden ratio rule. Will be very interesting to watch this unfold, maybe kinda like getting a peek into Pandora's box. Your planning on tri-amping the finished unit? I was wondering how the heil's efficiency would match the Altec's, tri-amping would fit the bill.

What you say about bracing affecting frequency response is a fact that I have noticed in the past and often feel is overlooked in a design. There are several DIY small business on the net that will build you a spare no expense cabinet and they always use judicious bracing. So much so that I can't imagine it not screwing the sound up and creating a bunch of problems on their own while trying to solve cabinet resonances. Sounds like a pretty thoughtful and intelligent approach your taking.

 

[specialidiot]

Had a good grin when someone from Minnesota says they hate winters,

As for the hatin' on the winter, this one has been longer and worse than any recent ones, we're at #5 in the rankings, now and a couple more inches will get us to #4.

In the Twin Cities area we have a 50/50 chance of a white Christmas, so that gives you an idea of when we start our snow cover season. It's not rare to be able to sneak in our last round of golf over Thanksgiving weekend.

It's also very common to be able to play golf on Master's week, which is in less than two weeks.

Our snow cover began in mid November, and there is no way we'll be snow free by the time the Master's gets going on April 4.

But we have faith it will happen. Although the mercury didn't reach 32f yesterday, the sun is warm and there is hope!

BTW, nice build you have going Lance.

 

[Russellc]

Lance, are you going to show dimensions so this project can re replicated?
I do have 416 8C and 802 8G here, and it is getting warmer out. Little chilly today, and maybe an inch of snow this coming saturday, but what the heck, we just had a day that hit 81 degrees and several in the 70's.

Point is, this summer is wood tool buy'in time and the gargage needs a project! These may be a little large.....on the other hand, I do have A-7s which are not very small.

Woofers need to be reconed again, a cat pulled off one of the little domes and shredded it. Driver works fine, really a shame as they were the original cones.

Maybe I can effect a repair, we'll see. If it doesnt look right, I'll just send them both in for recone, it drives me crazy when drivers dont match.

Good luck with the build!

Russellc

 

[Doc Zinger]

You MN guys are right I don't know what I'm talking about when it comes to sustained snow on the ground winter. Even in Wyoming you get chinook winds that can result in 70+ degree temps and snow melt. A visit there a few years ago had temps go from -36 below to 68-69 above in 36 hrs. Here in Seattle it doesn't get bone chilling cold just wet, damp, cool/cold temps never above 50 for 5 months.

Maybe these conditions cause us to want to build something to take our minds else where. Now that I got my car built, I think I'll get back into stereo gear, just need to figure out what to build.

 

[westend]

In the Twin Cities area we have a 50/50 chance of a white Christmas, so that gives you an idea of when we start our snow cover season. It's not rare to be able to sneak in our last round of golf over Thanksgiving weekend.

It's also very common to be able to play golf on Master's week, which is in less than two weeks.

Our snow cover began in mid November, and there is no way we'll be snow free by the time the Master's gets going on April 4.

But we have faith it will happen. Although the mercury didn't reach 32f yesterday, the sun is warm and there is hope!

BTW, nice build you have going Lance.

Thanks Jeff. I about half agree with that golfing schedule, the half that says a round in early April. Now if you had said," It's not uncommon for a few hard-core maniacs to try golfing at Thanksgiving".....wait, :scratch2:.....that's about all of the golfers I know.


Shawn, standby for Pandora's box to be built, I have been studying laminar flow and turbulence for a little while, today. I'm not too worried about the Heil matching efficiencies. Those things can run out on their own or be attenuated, they tend to be very unobtrusive. Triamping would, of course, be ideal and I have many amps.

Lance, are you going to show dimensions so this project can re replicated?
I do have 416 8C and 802 8G here, and it is getting warmer out. Little chilly today, and maybe an inch of snow this coming saturday, but what the heck, we just had a day that hit 81 degrees and several in the 70's.

Point is, this summer is wood tool buy'in time and the gargage needs a project! These may be a little large.....on the other hand, I do have A-7s which are not very small.

Woofers need to be reconed again, a cat pulled off one of the little domes and shredded it. Driver works fine, really a shame as they were the original cones.

Maybe I can effect a repair, we'll see. If it doesnt look righjt, I'll just send them both in for recone, it drives me crazy when drivers dont match.

Good luck with the build!

Russellc

No problem with the dimensions, we might as well wait for the "as-built" bonafides before I list them, though. My mentor has informed that since no other audio maniac has attempted this, they shall now and forever more be dubbed the "Westend's". I feel like I'm in the ranks of A. Bose, H. Ford or maybe just T. Crapper.

I wouldn't think a dust cap replacement would be that hard, RussellC. Maybe Bill at GPA could sell you a couple. I'm going to confess, now, that one of my 416's has a small repaired tear. It doesn't seem to make any difference, sound wise, and is barely noticeable.

Finally, I can say that all of the plywood panels are now cut. I ran most of them through the table saw to get everything as true as possible. That takes care of just about five sheets of BB plywood, if anyone is counting. At 65lbs./sheet that makes the weight per speaker around 160 lbs. without driver and additional bracing, glue or finish. I have an appliance dolly.

 

[westend]

Swept up a little and thought I'd put this up here about routing. I will be cutting over 40' of dado in the inside of the cabinet to join braces to the panels and each other.

I am using a Bosch 1617EVS 2 1/4 HP router with the plunge base and a 1/2" shank straight bit that is 23/32". The bit is available at MLCS woodowrking.

Again, out came the clamping straight edge and I set up a scrap piece to experiment. This plunge base has an adjustable depth rod and a stepped turret that is stepped in 1/8" increments. I loosened the rod , set the turret for it's highest step, and plunged the router motor down until the bit was at the top of the work surface (this was all with the router unplugged, of course). I then tightened the rod, released the plunge and turned the turret one stop to lower the bit into the work surface 1/8".

You can see from the attached pictures that I have the scrap work piece clamped and some additional scrap around the work piece to maintain the base across an even surface and the work secured. A few quick measurements and a test fit showed that I hit it within a blond hair of being right on. The width of the cut is just loose enough so that I won't have a lot of aggravation sliding panels into place and will have enough space for glue push-out.

The boxed set of bits is on sale right now at MLCS, for $19.95.

 

[ejfud]

Looking good Lance!

 

[shawnra]

WoW your going to set all your braces into dados! Holy crap Lance your a more adventurous guy then I.

Oh BTW everyone, good morning and a cup O'Joe for all.

 

[Altec]

I have already been admonished not to use cleats in the corners as this will also lead to some sort of auditory calamity.

My brain interprets some of this as "voodoo" and some of it I understand.

Hmm, that's a bit over stated, but coming from a hotrodding/racing background where folks live and die for tiny fractions of improvement in performance, I take the view that while adhering to some theoretical improvement may not be audible or even worth the effort, but if enough of them are adhered to they may sum to something worthwhile.

In the scheme of things, these boil down to potentially reducing the amount of damping required which in turn equates to increased electro-mechanical-acoustical efficiency, ergo potentially less power required, lower distortion.

This doesn't mean much when cabs are small for the BW since you only need it to be rigid/massive, but as panels get large enough to require bracing/damping, one needs to think in terms of high pressure air duct construction for max performance same as a horn or large air handling system.

GM