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I would like to share these specs for those interested.
The internal volume is around 16 cubic feet tuned to 28Hz, the -3db is @ 30Hz. I guess it is considered an Extended Bass shelf alignment.
You may notice the port is removable should I want to change the tuning.
The access hatch for installing the speaker is similarly recessed in, but is not visibly in the picture.
Six 5'x5'x 3/4" Void free Baltic Birch sheets were used.
The below WinISD simulations are based on 1 watt and around 3 ohm series resistance to generally accommodate the low damping factors of the amp(s) I intend to use them with.
I tried to decide to finish them nicely or go for the classic Altec grey finish.
To simplify construction, I went with the Grey paint on Birch-ply boxes, then some time down the road I may make some nicer panels to slip on to the front portion of the boxes.
Veneering is also still an option.
What you may not see in the picture is additional triangular bracing on the inside of the boxes. It is probably lightly braced by some peoples standards but it has been fine at the volume levels I listen to it at so far.
The back walls are lightly fleeced.
They do fit through regular doors and are surprisingly easy to slide around on the floor with the three nylon feet I attached.
As I mentioned in another thread, these use less floor area then the 5 cu foot Altec cabinets.
They are at a 50/40 degree angle as I find this more versatile then a 45 degree angle cabinet.
I am very satisfied with this project. I did not want to have a sub-woofer so this design works very well for me.
They sound effortless, very snappy and dynamic. They reproduce bass textures in a way that I had never experienced.
I suppose that is the advantage of having bass reproduced by a 15" paper cone that moves very little.
Follow Ups:
I'm happy to see your followup from a few days back, particularly the box tuning update. I am much closer to the point where I would love to have a pair of these (and make proper use of them), so I wanted to see if I could get some plans or internal dimensions. Back last December it was too far off to consider, but now it makes sense to do some planning.
thanks,
Skip
Let's start with the plywood layout to get familiarized with the pieces.
You will need six 5' x 5' x 3/4" Baltic Birch ply or equivalent.
Keep all your scrap as it is used for bracing and one set of the removable ports. (Not drawn.)
You will notice there are 8 triangles there, 4 of them will be ventilated for webbing/bracing, the other 4 remain solid and are used for the tops and bottoms.
I will add individual pictures detailing each piece.
It's pretty straight forward, you just have to keep in mind that the speakers are "mirror" images of each other, so it's best to mark everything with a one "1" for the left and a zero "0" for the right.
So which side is the right? Which ever you like, hence the binary number scheme. Isn't this fun!
Remember this is a 50/40 degree speaker, so you can switch em around to have a different angle. It is a very accommodating and versatile design.
These can be assembled with 18 gauge finishing nails (pneumatic gun) and some "titebond II" or equivalent.
Nails were around ~1 1/4" long if I recall correctly. The length isn't critical, they just need to hold it well while the glue dries.
My pair went together nicely so I didn't need any screws, that being said, it wouldn't hurt to have a few screws handy.
If you do need screws to help assemble, make sure you pre-drill any screw holes and glue in a wood plug. (Or 2-part epoxy wood filler)
You're also as a minimum need a bit of paint and some wood-filler for the nail holes. Regular wood fill is fine for these small holes.
I believe I got some Behr paint from the hardware store and coloured it "Antique Tin" as it seemed appropriate for vintage Altec.
It is a fairly flat paint, like a satin finish.
I wouldn't get anything too glossy if you are going to brush or roll it on.
Audio Illuminati
Here is the drawing for the braces.
Before we dive into this, these drawings are accurate to within 1/16".
Care should be taken when cutting pieces out. If you do cut a piece somewhat inaccurately, you may have to compensate for it.
Check all parts for a nice accurate fit BEFORE assembly.
This may seem obvious, but this is just a reminder as this cabinet goes together tight and with the beveled cuts on the corners it doesn't leave any room for error.
Mark out the webbing using the drawing below, you need 4 of them. You can cut them all the same as two of them can be flipped over to brace the other side.
Everything on the web is 1 1/4" wide, except for the curved parts.
The curves you can draw by hand, or use various sized round objects that are handy.
If you cut out the first one, you can use it to trace out the next three to save some time.
After it is cut out, use a router to round-over the edges of the inside cells only. (Don't router the outside edge.)
This isn't shown in the drawing below, but is visible in one of the earlier pictures.
I think I used a 3/16" or 1/4" radius router bit for this step.
This webbing fits into dados in the side walls.
Since plywood is not EXACTLY 3/4" inch, these dimensions need you to LEAVE 1/2" of material below the dado as opposed to removing 1/4"
This leaves the discrepancy on the inside of the cabinet, so that these dimensions will work regardless if your plywood is a little over or under 3/4".
Example, if your plywood is a little under 3/4", the dado will be a little less then 1/4" deep. Leave a 1/2" of material.
These outside dimensions are also used to cut out the solid top and bottom triangles.
Audio Illuminati
No problem.Here is a pair of sidewalls. They are 8" wide by 56 5/8" High.
The second picture has the measurements for the middle dados.
They are measured from the very top-downwards. These will be the same height on all walls.
The top and bottom are also dadoed.Reminder that the second pair is a mirror image of these ones.
Basically they will look the same as these, but the 20 and 25 degree cuts will be switched around.
Audio Illuminati
Edits: 08/04/15
This is the front wall.You will notice the backside of the speaker hole has a bit of a rebate around it. (Picture 3)
It is around ~1/4" deep. The diameter of this rebate is slightly larger then your duplex speaker. I don't recall what it was at the moment, so I just drew at 16".I recommend using a circle cutting jig with a router for the speaker hole.
If you are doing the back rebate, cut this first.
Have the main panel clamped down to the table AND also put a few screws through the part that you will be cutting out. This will hold the scrap still that the jig is attached to, assuring the cut finishes off nicely.Of course if you could use a jig saw if you have a steady hand and/or are going to put a grill cloth on it.
I suppose the back rebate for the speaker is somewhat optional if you don't have access to a router and circle jig.I did not round over the front of the speaker holes, I was concerned there would not be enough material left to keep the screws from poking through.
I did round over the port opening on the front of the panel. (The green opening below, that is 12" high x 13 1/2" wide)
This is for cosmetic purposes only, the round edge is a little more forgiving when matching up with different removable ports. It will hide minor variations in size.The orange port backer board does not need any round overs, it will be covered up.
The rest of it is pretty straight forward.
The orange backer board for the port is centered with the opening at the front. There will be about 1/8" space top and bottom from the floor and middle brace.
Audio Illuminati
Edits: 08/04/15
Here are the back walls.
Do as nice job cutting out the speaker access hatch, you will need the piece cut out to use as the door.
So these are all the main components. If you have any questions or need more measurements, just ask.
It is the triangle braces that define the shape. If they are slightly too large, it won't let the seams close completely. The triangle braces need to be the exact size or ever so slightly smaller for a tight assembly.
As you are putting it together, when the opportunity arises, you can add a second bead of glue on the inside to help assure any small air gaps are sealed.
Cut the left over scraps into uniform strips of around ~4" or whatever you can get. These will then have a 45 degree cut on each end to use for bracing support. Refer to the earlier pictures to see the bracing strips installed.
I don't have the measurements for them, just measure to fit as you go, the lengths not overly critical.
Infamous sockpuppet
And done! Once again, Thank you so much! Building these will represent a comfortable stretch on my woodworking skills. My room is coming along. Once it's done and set up with less exalted speakers that are ready to go. I'll jump on these.
Skip
No problem Skip.
That speaker hatch is 17 3/4" from the top, to center of the opening, same as the speaker side.
I forgot to label that dimension.
The edges around the hatch and the hatch also can be rounded over if you like for cosmetic purposes.
Cheers.
Infamous sockpuppet
So far, very very nice! I appreciate the effort.
Skip
Absolutely, actually I was thinking about that the other day.
I promise you this time I will put something up here.
Audio Illuminati
GargOyle ... super job (from one sawdust eater to another).
Everyone likes the skeleton bracing. I concur. You can't make a woofer or sub box stiff enough. Notice I didn't say "heavy". They are two different things. Bass is controlled by stiffness, not mass Unless a big bunch of it. I read years ago that 4" of concrete for a cabinet is considered non-resonant. My concrete floor in shop vibrates like crazy when the compressor ignites. Guess it would have to be 10" thick.
Pic of early Poly Natalia from a few years ago. Keep us posted as you tweak.
Zene
Thanks.
Hey that's a pretty sweet cabinet there yourself!
"Bass is controlled by stiffness, not mass Unless a big bunch of it."
I agree.
Lotsa questions! Background is that I have 605Bs in open baffles with bass support from 18" woofers in open backed boxes. I also have 3 604Cx that have new GPA cones an diaphragms, which I understand makes them almost the same as 604Es.
Your boxes for corners look fabulous and I have a room/application coming up.
1) Crossovers? I'm using modified Markwarts on my OBs.
2) Are you planning (and can you) make the design available? I am very happy to pay should you (reasonably) want to get some reimbursement.
3) Do you get a good phantom image fill at that spacing? The room I have is about 13' 10" wide and I might want to build a more appropriate box (big closed box) for a center. it would give up bass, but might work well.
Enough for now. Great project, and thanks.
Skip
Hi Skip Pack,
"1) Crossovers? I'm using modified Markwarts on my OBs."
I am using the N1500A crossovers. If I understand Jeff Markwart correctly these may be difficult to improve upon, although I "think" I can add his mid-frequency potentiometer to my circuits.
"2) Are you planning (and can you) make the design available?"
I have no problems making the plans available for others to use.
"I am very happy to pay should you (reasonably) want to get some reimbursement."
To be fair I based a lot of my decisions on valuable information that was put on the web by other contributors, so I don't think I would charge for these particular plans. Although what you proposed would be my dream job. :P
If you wanted something customized to your specifications, I could do that and would accept a donation of any amount that you see fit.
"3) Do you get a good phantom image fill at that spacing? The room I have is about 13' 10" wide and I might want to build a more appropriate box (big closed box) for a center. it would give up bass, but might work well."
Imaging is spectacular so far. I have a big desk and shelves that separate them, yet they still present a very good center image with 2 Channels, IMO, of course.
I will note that they are different sounding then any of the "small" box speakers I have owned. I will try and describe the difference.
-The small boxes, even when placed in corners are very interactive with the room, even at my near field listening position. Similar but not as extreme as open baffles.
-These "Garg0yles" were designed to be close to a "soffit" mount which focuses all of the energy in a forward direction, also known as "2pi".(This gives a decent boost in lower frequencies.)
In fact the first version was literally a 3 sided triangle, however these did not have enough volume, so the baffle was extended out a bit.
This has the effect of minimizing the room interaction especially at my near-field listening position. It was a little different at first, almost as though something was missing, it gives you a sort of isolation from the room similar to headphones. What was missing was reverberations that I was accustomed to hearing with small speakers bouncing sound around the room in all directions, also known as "4pi" space. I quickly grew to like this effect.
Cheers.
Holy crap! Now that's a speaker! Amazing stuff. Approx, how far apart are the two duplex's.
Cheers
FM
Thanks, the room is 11 feet apart where they are located.
nt
I decided to give the boxes a tune-up, to around ~37Hz.
It's got a bit of a ski jump before it rolls off, sounds alright though.
Technically I lose a little bit of bottom end with these ports, in actuality sounds like more bass as the energy is pushed up a little higher.
Sounds nice.
Still haven't mounted the binding posts.
Also I might tackle some new crossovers in the fall. I don't really want to modify the stock ones, so will most likely clone what is there. (N-1500A)
Audio Illuminati
30 hz.
It's an over-damped alignment, which will blend well with the room-corner gain, and will sound more like a sealed box.
I don't think it's a good idea to have a peak like that along with corner gain.
Warmest
Tim Bailey
Skeptical Measurer & Audio Scrounger
Hi Tim.You would have to give me an example as I am visualizing a QB3 alignment being a small box of a couple of square feet.
I might be able to figure out a port that is somewhere in between QB3 and EBS.I rocked the 604's in some ~5 cubic foot Flamenco cabinets for a while.
The smaller box for me doesn't utilize the 15" speaker to it's potential.
One seems to have to work pretty hard to coax low end bass from these mid rangish woofers. Especially to compete with the horn section.
Even though the Xover has an L-Pad, it doesn't really balance the low and the highs like one wants.
It just removes atmosphere and other good traits of the horn and puts emphasis on the lack of bass in the smaller cabinets.Granted there may be a better tuning for a particular room, one day I will get around to actually measuring the in room response with the different ports.
I have done some bass sweeps by ear, as mentioned it sounds OK. I notice the slight reduction at around 60Hz - 70Hz in sweeps with these current ports, but nothing major.
There doesn't seem to be any audible peak above 0db in practice, measurements may tell me otherwise.FWIW some of the original Altec cabinets have that little kick at the end, although I'm not sure what the intention was,(probably not corner loading)aside from trying to maximize output with the somewhat bass shy 15" drivers.
As usual compromises must be made, however the big box does have a lot of good traits by being so large, things like group delay, cone excursion, baffle step, port noise etc are kept to a minimum, thereby approaching the traits of a sealed box when a sealed box isn't practical.
Plus who doesn't like really big speakers.
Infamous sockpuppet
Edits: 08/05/15
Sometimes the driver and Vb combination is unsuitable. But that would be a sign that an RB probably isn't appropriate either.You do have access to box design software? Does it allow you to factor in an active high-pass filter? Try that idea too. This can eliminate cone bounce below fb and still give very deep bass.
With a QB3 the fb lies below 0db and the roll off is slower than usual, not as slow as an EBS. IME they don't boom.
One other thing? Get a copy of Bullock on Boxes, and read it.
Warmest
Tim Bailey
Skeptical Measurer & Audio Scrounger
Edits: 08/06/15
I have WinISD, I think it has the ability to enter a high pass filter.
Will look into getting that book. Lol still have to read the cookbook I have now.
Cheers.
Infamous sockpuppet
I tried to look up the specs for the N 1500-A, but only found real specs on some enthusiast desinged ones. I'm sure 1500hz is the xover frequency, but what slope? I saw the newer designs were second and third order.
There has been lots of talk around here lately of active crossovers. If I had to give only one reason to use one, it would be the 1500hz crossover point is in precisely the worst spot for human hearing. A steeper crossover slope might help with the slight misalignment of drivers. They are not like the time-aligned concentric Tannoys.
Usually I wouldn't give a rat's butt about one quarter of a millisecond, except for it happens to be at 1500hz.
-----------------------------------------------------------------
Big speakers and little amps blew my mind!
Hi.
The N 1500-A has a second order high pass for the horn and a first order for the woofer.
It is a series connected crossover.
As far as simple crossovers go, the N 1500-A is decent (apparently). I could maybe add the mid frequency EQ as devised by J Markwart.
Another consideration is to build a set of Mastering Labs Xovers.
AFAIK these somewhat correct the alignment, if I am understanding them correctly.
Of course I could consider something active, although then I would have to build some woofer amps etc.
I am really enjoying the simplicity of my little monoblocs.
Here is the N-1500A schematic, as well as the Mastering Labs.
Audio Illuminati
The ML is more complicated than the one I liked. For the ML I would use air cores for the inductors. The link is one that caught my attention. It moves the xover point to 1240hz.
I hear you about the one amp thing, but allow me to blather for 30 seconds.
You already have a bass amp. Your 2a3. You optimized it for good bass. I bet you still have that RH84 laying around. I bet it sounded fine 1500hz and up.
You can get an analog active xover for $500, or for the same price a PPXLO, both from Marchand. That's your only extra cost. Bet you even have an extra set of interconnects.
----------------------------------------------------------
Big speakers and little amps blew my mind!
What the heck, I will entertain that suggestion and look into some analog active or PPXLO options.
Audio Illuminati
That's the spirit.
Good to have you back.
---------------------------------------------
Big speakers and little amps blew my mind!
Thanks, cheers.
Audio Illuminati
That is an Altec 604, right?
The braces are Art!
At the request of the Moderators,
This space has been deleted
nt
nt
nt
nt
Lol, I guess I could spin one around and open the back up.
The crossovers are just sitting on the floor, as you probably noticed from the wire coming out of the port.
I will make external boxes for these as well some time.
Yes they are 604E.
They also could use some binding posts. If I don't figure out some sturdy DIY ones I may just pass the wire through a small hole and glue.
Cheers.
Lately I've been taken with the design of Speakons. They would look good on these. You could put one on each side panel so it would always be easy to hook up regardless of the 50 or 40 degree orientation in the corner. Just use the one on the convenient side.
Skip
That is a pretty good idea.
I will look into it.
Infamous sockpuppet
nt
nt
nt
nt
Sorry for the multiple posts, I will have to figure out how to place them in one post next time.It's hard to described how excited I am with these. :P
Cheers.
Edits: 12/09/14
Garogole, I do not blame you for being proud of the test results your bass horns have displayed. The results are exemplary, but I wonder why you haven't described how they sound to you when playing music, especially music with a strong, percussive, rhythmic bass component.
The coherency of the bass is amazing.
My other speakers have flooded the floor with thick muddy bass. These are very nimble and vapor like, like a fog the frolics around you then strikes you in the chest with a cafeteria tray without warning.
That's what I was describing earlier as snappy, they can reproduce bass with a hard attack, or should I say accurate attack.
I feel I am experiencing more of the bass fundamental notes as opposed to hearing higher harmonics.
Steel drums and timpanis sound amazing! Specifically the attack.
I like having no crossover in the bass range. They have strong integrated bass that does not bother with the human voice. Incidentally I have not noticed any apparent flaws at the crossover point, (1500Hz) so they do a pretty good job.
Of course all the usual Duplex goodness applies, I was focusing on the low frequency production here.
The last post was a reply to Don Reid's question.
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