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Old 1st December 2012, 08:52 AM   #441
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Quote:
Originally Posted by GM View Post
Anyway, I check every driver I'm dealing with:

n0 % = 9.6352e-10*Vas*Fs^3*[1/Qes]

Sens [dBa] = 112.018+[10*log10[n0]]

Sens [dBv] = 112.018+[10*log10[9.6352e-10*Vas*Fs^3*8/[Qes*Znom]

Hope I copied this right, it's from an Excel SS done by someone far more math oriented than me.
I hope so Greg or we're both stuffed, since I've got exactly the same math loaded into my Sheet of Many Things.

Last edited by Scottmoose; 1st December 2012 at 09:13 AM.
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Old 10th March 2015, 04:56 AM   #442
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Wink Avebury Resurrection...

I just finished reading an awesome thread that had an awesome project at ended abruptly. So I figured it was time for me to post my Avebury happenings, as I do realize how helpful these building threads can be...

Life has been a roller coaster ride the last couple of years between working like a mad man in the summertime to off set the sheer lack of work (and the accompanying worries) in the winter. It was really a good thing I paid of all my consumer debt, as acquiring a new career these days is a whole new challenge in and of itself, especially in a rural, snowy, and simple life culture like Ironwood, Michigan. Thankfully, years of preparation and grueling job hunting has paid off, and I will be starting a new career at the local hospital that is secure, steady, year-round, and allows many options for advancement. The best part about this journey is I got a good idea of what my daughter will be undertaking as she gets ready to seek out her career in our highly specialized, competitive global market. Got to get her through High School first.

I figure I had better post my audio adventures over the last couple of years, as I may drop out again for awhile when adjusting to my new career.

I have a lot to share, so I will try to be coherent.

I got the front mosaics to the Aveburys done a year and half ago. I still have a lot of sanding to do on them before I would consider them completed. As it stands now, I will be making a similar mosaic on the back and cutting six inch wide strips 1/4 inch thick of black and white ash for the sides. I have looked into veneer, but the stuff I have access to is pretty thin and low quality. The hardwood Ash I got was a trade for a computer build I did for a friend, so the price was right.

Currently, I am using Avebury in a FAst 4.2 system. The Avebury are the main left and right. The Cheap and Cheerful arrays are back left and right. And I have a pair of Dayton HF 12" subs in experimental 3 cubic foot cabinets
for bass. I am running the system through my on-board computer Realtek Audio card, mainly, as I can run Dolby Digital and DTS soundtracks. I have upgraded my CPU, Graphics Card and now run all software and music off a Solid State hard drive. This all made a significant improvement in the sound (and video) quality in regards to micro details, timing and dynamics, despite the inferior DACs. With the current DACs, it is a toss up. The Realtek offers up to 7.1 channels, where as my M-Audio is over all better, but stereo only. I have acquired a Twisted Pair Buffalo III kit, but I have not assembled yet. I am thinking of making that into a four channel DAC with a MiniSharc DSP board for cross-over and EQ control with a USB controller, so I can run multi-channel from my PC. There is still a lot of design work to consider before building the Buffalo.

Anyway, as it stands, Avebury has a high-pass 12dB/octave cross-over at 80 Hz and the Subs handle 80 Hz on down to 22 Hz in room. Like I say, the M-Audio DAC has a more "resolved" sound and is not as forward as the Realtek, but as the Avebury is no longer asked to do the Sub-sonic stuff, so the mid-range has a tad bit more presence. There is also a lot more headroom. I can pretty much play this set-up as loud as I want. There are only a couple of songs I have that clip the amps with intense mid-range attacks. On the most part, I have to be careful, as for most source material, it is easy to play too loud, as loud is CLEAR. I think I have always associated too loud with distortion, but this is not the case with this system.

All and all, I still prefer the "presence", scale, and encompassing sound of arrays, BUT, there is a "magic" to the layers and layers of dynamics the Alpair 12 possesses. And this will only get better with the Buffalo DAC. Really, the short coming of the Avebury, at least for the sonic bliss I am seeking, it is not an array. My goal is to have the Alpair 12 sound in an array format. May as well Dream Big.

I really like using the subs with Avebury. There is a slight integration hiccup using the subs verses running full-range. I am sure this is caused by the timing between the rear horns and the front-firing subs, BUT this is a compromise that I am personally willing to take. The Alpair is allowed to do what it does best with no IM Distortion what so ever. If you are listening to Jazz trios, then by all mains, run Avebury full-range, but when watching Star Trek, it is time to fire up the subs! I think the bass with the subs is more "relaxed", effortless and lower. Once and a while there is an ill-defined bass rift due to the above integration hiccup, but this is only noticeable with some music. For movies, the subs are the way to go, hands down.

The funny thing about the subs, is I am building them for my brother. He has a dedicated Home Cinema room in his house in Dallas, Texas. I am refining my 777 open baffle system for his mains. I will also by taking the Aveburys down to audition in his room. I am thinking he might like the Avebury in the front with the open baffles in the back for surrounds. It is going to be interesting comparing the two when they are both finished. Thankfully, it is going to be awhile before I can pull away from my new career to deliver and set-up his system in Dallas. So I will get plenty to playtime yet. And even if the whole rig ends up with him, I can fund my upcoming array build, maybe with something like a Fostex FF85w. I think having 25 FF85w's per cabinet would be the cats meow. Either way, it is a win, win.

More to come...

Allen
Attached Images
File Type: jpg HT Central.jpg (884.6 KB, 52 views)
File Type: jpg HT Left Avebury.jpg (791.0 KB, 52 views)
File Type: jpg HT Right Avebury.jpg (913.4 KB, 50 views)
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Old 10th March 2015, 05:34 AM   #443
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Quote:
Originally Posted by ArtsyAllen View Post
...upcoming array build, maybe with something like a Fostex FF85wk I think having 25 FF85wk per cabinet would be the cats meow.
It would be VERY interesting

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Old 10th March 2015, 06:19 AM   #444
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Default Array Dreams

Quote:
Originally Posted by planet10 View Post
It would be VERY interesting

dave
Thanks Dave, I have been following your projects with the FF85wk, Alpair 7 and even the Vifa NC9FD00-04, and I have realized, like You, there are "un-measurable" aspects to drivers that set them apart. I can EQ my Cheap and Cheerful arrays to the frequency response of the Avebury, but they can not come close to the layers of dynamic detail of Alpair 12. I can build a Vifa array and that probably would outperform the Cheap and Cheerfuls. BUT, first of all, that has been done already, and secondly, if I was to go through the work of building a Baltic Birch cabinet for 25 drivers, with solid wood mosaics, I may as well take the extra step with a higher performing driver. I have a feeling it is going to take some time to build these cabinets, so I can buy the drivers over a period of time.

I do have one inquiry, have You listened to any of the Celestion Array drivers: AN 3510, or AN 2775. The main reason I am considering these is they appear to be built well, especially for line array applications. I may need to have a driver blowout between these and the Fostex.

Now back on topic...
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Old 10th March 2015, 06:29 AM   #445
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Post Begining the Mosaic

Here is how I went about the mosaics.

I first cut the arcs out of the pieces to fit around the Alpair. I used a shoe lace so I could remove the Alpair without taking the Avebury cabinets off the clamping stands. Note that I cut the oak pieces to the thickness of the Alpair bezel, now making it flush. This was a very labor intensive method of rebating the driver, but I like the aesthetics...

Last edited by ArtsyAllen; 10th March 2015 at 06:35 AM.
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Old 10th March 2015, 06:53 AM   #446
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Default 3rd attempt at photos...

Clamping jig and Alpair laced for removal...
Attached Images
File Type: jpg Gluejigs.jpg (381.1 KB, 34 views)
File Type: jpg Alpair12LacedUp.jpg (635.1 KB, 33 views)
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Old 10th March 2015, 06:55 AM   #447
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Arcs cut for driver rebate and clamping...
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File Type: jpg Baffledrivercutout.jpg (241.4 KB, 17 views)
File Type: jpg Alpair12yikes.jpg (521.1 KB, 15 views)
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Old 10th March 2015, 07:12 AM   #448
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Post Gluing jig...

For the remaining tiers of the mosaic, I created this gluing jig. If you have ever glued wide pieces of wood with pipe clamps, You may have noticed that the middle of your board can "bow" in the middle, therefore not gluing flat and tight in the middle. To solve this problem, I varied the thickness of the contact boards, making the middle board the thickest and each successive board a little thinner towards the outer edges. So when the cross member boards bows, due to bearing the pressure of the clamps; the contact boards would be fully engaged to their respective pieces, ensuring a tight fit...

This is clear as mud I am sure. If any one wants more information on what I am trying to explain here, let me know, and maybe I can draw something up that would illustrate this better.
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File Type: jpg ClampJig.jpg (832.1 KB, 13 views)
File Type: jpg ClampJigInUse.jpg (560.0 KB, 7 views)
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Old 10th March 2015, 07:21 AM   #449
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Post Glue Steps 1-4

These next photo groupings show the steps in detail I took to glue each tier down. These first four are dry fitting, applying the glue, aligning the jig and installing the first clamps...
Attached Images
File Type: jpg GlueStep1.jpg (577.4 KB, 7 views)
File Type: jpg GlueStep2.jpg (473.1 KB, 5 views)
File Type: jpg GlueStep3.jpg (491.3 KB, 6 views)
File Type: jpg GlueStep4.jpg (520.0 KB, 4 views)
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Old 10th March 2015, 07:30 AM   #450
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Post Gluing steps 5-8

Step 4 above shows that the first order of clamping is making sure the pieces are staying in alignment and snug. Step 5 is the clamping for the downward pressure of gluing the mosaic tier to the cabinet. Step 6 applies more side pressure to prevent the individual pieces from separating. I then waited about 20 minutes for the glue to form that initial bond. I would then remove all the clamps and jig (step 7) and start cleaning excess glue (step 8)...
Attached Images
File Type: jpg GlueStep5.jpg (546.2 KB, 4 views)
File Type: jpg GlueStep6.jpg (556.1 KB, 4 views)
File Type: jpg GlueStep7.jpg (484.0 KB, 3 views)
File Type: jpg GlueStep8.jpg (490.8 KB, 3 views)
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