Line Array in the works at Stryke Audio. (2 Viewers)

[Chuck Bogie]

Cool... The 5/3/3/5 looks like it's about right - the receiver that's gonna run 'em is an old Marantz 2230, and while it'll allegedly run a four ohm load without breaking a sweat, I'd really hate to let the magic smoke out... It's also only a 30 watt receiver, but hey, it's what I've got for that room right now... The speaks may end up with a monster old Pioneer, a Denon 1803, or (gasp) hooked up to a Phase Linear 400, depending on the occasion...

These are admittedly going to be more "party" speakers than "audiophile" speakers... Bought a case of the 4" pioneer buyouts from Parts Express...

I'm probably going to cross 'em at around 5,400, at least for starts... Going to run a line of either the Onkyo textile dome buyouts ($0.48 each, 25 per speaker) or the little Apexes, with a rudimentary crossover, and suck up the fact that I'll be getting some crud in there, until I can afford to bolt on a line of the Dayton ribbons... then I'll spend some time/$$ on a crossover at around 3,150ish... probably will also end up with a different power tapering schema then, since I won't get the SPL gain from the multiple ribbons.

The enclosure is basically going to be a three-sided box with the 4" drivers on the "open" side (well, it'll have a top and a bottom too...). Due to the construction of the faceplates, mounting 'em will be "interesting." When I add the tweets, I'm just going to put 'em on a board (possibly a double-thickness of 3/4" MDF with braces) that'll bolt to the side of the main enclosure. Won't be pretty, but the MDF's getting a coat of flat black anyway... Will probably round over the edges with the router...

Haven't completely decided on sealed vs. vented yet either. May try a box size that'll work fair with both, and make two different backs. I'll need the equivalent of three 4" vents, if I've figured it correctly...

Regardless, punching 25+ holes/speaker is going to be interesting...

Okay - now if I look at the re of the Onkyos (3.5), I get a 9/6/6/9 (figuring 30 speaker line) for a total value of 6.3. That's doable. On the other hand, figuring a re of 7.5 for the 4" drivers, I get 7.03. Also doable. Now here's the rub - The 4" driver (x 16) appears to be very slightly more efficient than the tweeter (x 25-30, depending...). But with more tweeters than woofers, I'm going to see a boost in the "tweeter range," right? Sounds like either a bit of padding, or I go with something on the order of a 9/7/9 (25 tweets) for an impedence of 9.6...

Happiness is a warm soldering iron...

 

[Rick Craig]

The Linus "2" turned out very well and we are talking about a more deluxe version. Stay tuned.

 

[Brett DiMichele]

Guys,

I am curious.... Don't take it the wrong way.. We all
appreciate the knowledge and expertise you have about Line
Array design. But I started this thread specificaly for the
Line Array that John is designing, and the Line Array I will
own. And it's turned into a Linus PlugFest...

I think if we want to discuss the Linus and it's siblings
then we should start another dedicated topic for those
particular offerings. Because I started this thread dealing
with John's LA and not just LA's in "general". If you have
info to add to the design of Johns LA or have critique's
about John's array that's cool post it here. But if you want
to discuss the design philosphies of the Linus and it's
siblings lets start another topic.

Is that a reasonable request?

Thanks!

 

[Chris Tsutsui]

lol Brett, you know you're thread has been robbed when Rick Craig himself is telling you to stay tuned for the The Linus "2".

Nothing wrong with a little temptation/competition IMO.

 

[Brett DiMichele]

Chris,

Heh I have been 0wn3d!

 

[Rick Craig]

Brett,


Sorry for appearing to hijack the thread. John is a nice guy; in fact, he had me evaluate his 7" woofer last year.

 

[Brett DiMichele]

Rick,

I know you and Jim are not Hijacking the thread and I know
both you guys flat out know your stuff! But I created this
thread because I want to let people know about this LA. I
would like to see a group purchase on these in the future
when John has the design(s) completed. This is the LA that
I decided on and I would like to share it with others.

I have no quams about another thread dealing specificaly
with the Linus and it's variants or even a general LA
thread, as I am quite confident that you and Jim as well
as numerous others would have much valuable information to
contribute.

 

[Patrick Sun]

Just an FYI: The HTF does not support group purchases/promotions, but nothing should prevent folks to do it off line, but, please no soliciting for this sort of activity on the forum itself, unless you get the approval from the owners, Ron and Parker.

 

[Brett DiMichele]

Patrick,

Understood.. But may I ask a question?

How did the Tumult Group Purchases come about? I have been
here a while now and I have seen numerous raw driver goup
buys listed here (adire, Stryke etc.)

I didn't think a purchase of the drivers would be against
the rules (I don't want to do anything outside of the rules).

At any rate.. I will keep people informed and direct them
to the web site for more info. I don't work for John this
is just something I am seriously purchasing for myself and
I figure there are other DIY'rs who can also reap the benefits
of such information.

 

[Patrick Sun]

That was not a group purchase being funneled through the HTF, but rather an early-bird offering through the grapevines. If a vendor wants to make special/exclusive offers to members of the HTF, they need to clear it with the owners, and come to an understanding in terms of advertising issues.

In the past, HTF-sanctioned group purchases were looked at, and discarded due to liability concerns when things go wrong and the vendor leaves members high and dry.

 

[Brett DiMichele]

Pat,

Makes sense

 

[John E Janowitz]

Hi Guys,

I have a little progress to update here on the enclosures now. They will actually be fairly easy to build with the exception of cutting a 1/8" deep by 5/8" wide notch along the back side of the baffle, side panels, and back. The front baffles are going to be 12" wide. That is really as narrow as they can get and still fit the drivers next to each other. My intention was to use the AIT 2" radius MDF quarter rounds. The nice thing about these quarter rounds is that they have a rabbet on them so that the front and side fit right on. You can then glue and nail, glue and clamp, glue and screw, etc and everything is aligned perfectly.

The only issue is that they don't have a 2" that fits a 3/4" thick front baffle and side panels. The option nos is to go with the 2" radius with the 5/8" rabbet and notch the MDF at the corners. It actually makes the inside line up very well for braces. The braces end up just being rectangular with 45degree angles cut on all 4 corners. There will be some cutouts for airflow, but I will show these in the CAD drawings soon.



I will have some pics of the assembled cabinet tonight. Then I will be starting work over the weekend on the Xovers.

John

 

[Brett DiMichele]

John,

Looks like a nice strong corner to me!

Can't wait to see the pictures

 

[John E Janowitz]

CABINET CONSTRUCTION PT. 1

Well, I ran into a slight problem in working on these. I thought I had 4 of the MDF corners, turns out I only had 3. I will have to use a 2" radius plywood half circle for the final corner in this first one. All my documentation will show for a normal array with the 4 MDF corners though.

Here are the first construction pics of the line array. The first step was to have the CNC router cut the front baffles. If you don't have a CNC router, you can do this by hand with a router and circle jig, and a template for the tweeter cutouts. Baffles measure 12" wide x 88" tall. The first pic is the CNC machine just done with cutting out the baffles.

Baffles on CNC router

The next step is to route out some notches at the back of the midbass mounting holes. This is a good idea to do in any installation. Without doing this, airflow can be somewhat restricted, and the round cutouts if too deep can actually lead to a resonance you don't want. In the case of this line array with 12 drivers, that resonance would be multiplied by 12, so we definitely want to avoid that. Some people use a roundover bit, which does help with airflow, but not with the resonance issue. You want to take a 45 degree router bit with a wheel on it so you don't cut too deep. Put marks on the back of baffle for where your screw holes will go, and try not to cut notches at those points. Here is a pic of the bit setup, and picture of one hole all notched out.

45 degree router bit set to cut

top hole in baffle notched out

After the holes are notched out, we now need to create the notch in the back of the baffle to get it to line up correctly with the MDF quarter rounds. The notch needs to be 1/8" deep and 5/8" wide. I setup a bit on my router table to make a cut 1/8" deep and aligned the fence so it would cut 5/8" wide. You could do this with a 5/8" rabbet bit on a router by hand, a dado blade on the table saw, or multiple passes with a regular table saw blade set to 1/8" high.

notch in back of baffle for mounting to quarter rounds

My next step was to show how to attach the baffle and back pieces to the quarter rounds. Unfortunately, my digital camera did not transfer these pics correctly. I will have to post these a little bit later if they are still on the camera.

John

 

[Bill Fagal]

Hi John,

Droolin' on yer CNC router!

Oh, the the sawdust I would make with a tool like that! Been dreaming of a hexapod router, but that's another story altogether.

Could you set it up for production to do the scallop cuts behind the drivers, or will that have to remain hand-work?

Also, are those corner pieces available to DIYers?

Bill

 

[John E Janowitz]

Hi Bill,

I can't really set it up to do the cuts on back. Well, I could, but it would be hard to align the piece properly once it's already cut from the sheet. I'd also have to change the bit on the router to do that. Not really worth it, so I just do it by hand. I'm actually planning a jig I can just trace with the bit to make those cuts, but haven't made it yet.

The MDF quarter rounds are available to anyone. They come from Anderson International Trading. Here's a link to the actual page in their online catalog.
Anderson International Trading - MDF Quarter Rounds

They aren't too pricey, $15 each, so you'd have 8 of them total for a pair of cabinets, $120 total. They have so far been a very good company to order from. They are pretty good with shipping too with no extra added on charges.

If you really don't feel like spending the extra, you could always just go with flat MDF panels, making the cabinet 16x12 rectangular and using a 3/4" or 1" roundover bit on the router then. All you would have for cabinet costs then would be 2 1/2 sheets of 3/4" MDF per pair.

John

 

[John E Janowitz]

Oh, and FYI, I did a little more of an update on my forum and added thumbnail pics. I'll copy the info over here in a little bit, but for now here's the link over to it.

Line Array Project

John

 

[Brett DiMichele]

CABINET CONSTRUCTION PT. 1

Well, I ran into a slight problem in working on these. I thought I had 4 of the MDF corners, turns out I only had 3. I will have to use a 2" radius plywood half circle for the final corner in this first one. All my documentation will show for a normal array with the 4 MDF corners though.

Here are the first construction pics of the line array. The first step was to have the CNC router cut the front baffles. If you don't have a CNC router, you can do this by hand with a router and circle jig, and a template for the tweeter cutouts. Baffles measure 12" wide x 88" tall. I will have a CAD file showing proper driver placement shortly. The first pic here is the CNC machine just done with cutting out the baffles.

[url=http://www.stryke.com/line_array_project/01-cnc-router-sm.jpg]
Baffles on CNC router[/url]

The next step is to route out some notches at the back of the midbass mounting holes. This is a good idea to do in any installation. Without doing this, airflow can be somewhat restricted, and the round cutouts if too deep can actually lead to a resonance you don't want. In the case of this line array with 12 drivers, that resonance would be multiplied by 12, so we definitely want to avoid that. Some people use a roundover bit, which does help with airflow, but not with the resonance issue. You want to take a 45 degree router bit with a wheel on it so you don't cut too deep. Put marks on the back of baffle for where your screw holes will go, and try not to cut notches at those points. Here is a pic of the bit setup, and picture of one hole all notched out.

[url=http://www.stryke.com/line_array_project/02-router-bit-sm.jpg]
45 degree router bit set to cut[/url]

[url=http://www.stryke.com/line_array_project/03-back-of-baffle-sm.jpg]
top hole in baffle notched out[/url]

After the holes are notched out, we now need to create the notch in the back of the baffle to get it to line up correctly with the MDF quarter rounds. The notch needs to be 1/8" deep and 5/8" wide. I setup a bit on my router table to make a cut 1/8" deep and aligned the fence so it would cut 5/8" wide. You could do this with a 5/8" rabbet bit on a router by hand, a dado blade on the table saw, or multiple passes with a regular table saw blade set to 1/8" high.

[url=http://www.stryke.com/line_array_project/04-notch-baffle-back-sm.jpg]
notch in back of baffle for mounting to quarter rounds[/url]

My next step was to show how to attach the baffle and back pieces to the quarter rounds.

John
------------------------------------------------------------
CABINET CONSTRUCTION PT. 1 continued...

I got the other pics off the camera, so here is the continuation of part one actually.

The next step after the baffle is prepared is to make the back and sides of the enclosure. The back is the same size as the front, 88" x 12" wide. Sides are 88" x 8" side. If you are doing a sealed enclosure you don't need to worry about port cutouts at all. If you are doing the vented enclosure now is the time to make the port cutouts in the back before assembling anything. From the inside, make 2 cutouts 4" diameter all the way through. Then on the INSIDE make a 1/4" rabbet all the way around about half way through the MDF. If you are using a circle jig to make the holes, cut half way through at 4.5" diameter and then all the way through at 4" diameter. This allows a nice spot for the 4" pvc to sit in snugly and then we can round the outside with a roundover bit later.


[url=http://www.stryke.com/line_array_project/05-port-cutout-sm.jpg]
port cutout showing 4" PVC sitting in recess[/url]

Then the side pieces and back all need to be notched for fitting with the MDF Quarter rounds. The same notch, 5/8" wide by 1/8" deep goes on all vertical edges. You can see the MDF quarter round here possibly better visualize how the pieces fit together.


[url=http://www.stryke.com/line_array_project/06-quarter-round-end-view-sm.jpg]
end view of the long 2" mdf quarter round [/url]

After all your pieces are notched, it is time to attach the quarter rounds to the back and sides. To do this you can use many methods. I used pocket hole screws for this one. You have to do this from the outside though because with the notch cutout on the inside of the panels there isn't enough mdf to hold securely. I used a Kreg pocket hole jig, but you could use other ones as well. I put the holes 2" from each end and every 6" along the panels. Draw lines across on the outside of the side and back pieces at these intervals. You will use the lines again later to line up the internal bracing. If working alone, the pocket screws make things very easy. You can get a jig anywhere from $15 up to about $300. I have the Kreg Pro Pack kit that is arund $130 myself. I believe you can get the drill bit and their small jig for about $35 though.


[url=http://www.stryke.com/line_array_project/07-pocket-hole-sm.jpg]
Drilling the pocket holes[/url]

You'll want to drill the holes on both edges of your side panels and back panels, but not the front. Attach quarter rounds to both sides of the back panel, and to the front edges of your side panels first. Then attach your side panels, with the front quarter rounds already attached to the back quarter rounds. If you try to put the sides on the back before attaching the front quarter rounds, you won't be able to fit the drill in there to screw into the front quarter rounds. Hope that makes sense. We will attach the front baffle later on with a different method once all bracing is in place.


[url=http://www.stryke.com/line_array_project/08-assembled-back-sm.jpg]
Back assembled to both quarter rounds[/url]

The next step is to make the top and bottom, and to put in the bracing. I should have pics of that by tonight.

John

 

[Mark_J_H_Jr]

John,

Will you put a grille cover on the speakers?

If so, are you going to document that as well?

 

[John E Janowitz]

Hi Mark,

Guess I hadn't thought about a grill yet. I guess I can address that as part of the finishing for the enclosure when I get to that step. I don't usually make grills for too many speakers, but if you want that as an option I will go through and document that also.

John