***Working Man's DIY Dedicated Home Theater*** - Page 19 - AVS Forum
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post #541 of 647 Old 08-01-2013, 03:21 AM - Thread Starter
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Thanks JD!


I have made huge progress on the baffle wall install but I'm holding out on pics until its finished......

However here's one pic to prove work is being done! wink.gif

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post #542 of 647 Old 08-01-2013, 04:25 AM
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Nice work, Nick. That baffle wall appears to be a 1-2 cases of beer project!!!

One question on your speakers....for the upper horn you have a slight flare-out to accommodate the molded insert piece....does this have anything to do with the functionality or performance of the speakers (to maintain a precise internal cubic volume, for example)?
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post #543 of 647 Old 08-01-2013, 04:37 AM - Thread Starter
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Hey Tim!

No, the crossover was designed with a 14.5" baffle in mind so thats what i built out the speakers to..... However the baffle wouldnt accommodate the 3/4" roundover i wanted to use on the sides of the waveguide without getting into it... Soooo, i came up with this idea if a dual roundover profile and liked the way it looked. Kinda makes the waveguide stand out more IMO.

I spoke with the designer and he said it wouldnt functionally change anything from a performance standpoint.

Yeah, im up to about 3/4 case now..... One six pack of craft beer at a time anyways..... ;-D
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post #544 of 647 Old 08-08-2013, 03:35 PM - Thread Starter
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OK so I've been super busy on this project. I had some issues with the speaker crossover which now have been resolved.

The provided crossover schematic was incorrect with respect to the polarity of the compression driver polarity. After the install was complete I thought the new SEOS speakers sounded good but just not "right".......

Measurments revealed that the polarity of the tweeter was incorrectly specified on the crossover. I recently got all that straightened out and they now sound right!!!!

Most notable improvement is in the vocals clarity and presence. The midrange of these things is incredible it really does grab you with the power and clarity. I have been able to approach reference without listener fatigue increasing the listening volume of my mains by about 10db without any introduced distortion..... I was listening at -14 as I am very sensitive to distortion, but I have found -5db to be my preferred listening volume with this current setup and thats plenty loud, trust me! biggrin.gif

All this makes perfect sense since I increased the sensitivity of the mains by about 10db and the amplification is the same....

To get all the way to reference I need either more power or more capable mains or maybe both IDK.... Doubling my power should net another 3db assuming I am clipping the amp, but thats still a db or two from reference.......

Anyways heres some pictures of the speaker installation, it was a fun and rewarding adventure!!!
















Woop Woop!!!!
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post #545 of 647 Old 08-08-2013, 03:54 PM
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Looks terrific, Nick! Did you measure the room yet?

Tim
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post #546 of 647 Old 08-08-2013, 04:25 PM
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How about, "did you get good outdoor measurements with your baffle wall?" Or is there a good way to get meaningful measurement data down to the crossover in the room? I want to know how your baffle wall is working!
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post #547 of 647 Old 08-09-2013, 04:37 AM - Thread Starter
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Quote:
Originally Posted by HopefulFred View Post

How about, "did you get good outdoor measurements with your baffle wall?" Or is there a good way to get meaningful measurement data down to the crossover in the room? I want to know how your baffle wall is working!

Quote:
Originally Posted by Mr.Tim View Post

Looks terrific, Nick! Did you measure the room yet?

Tim

I have been working solely on the crossover issue with the speakers.... I havent addressed the room at all yet.

There are some issues that stood out as needing treatment but the measurements I have done were very primitive and mostly nearfield when working on the speakers themselves so I don't really have a good answer for you guys yet.

I do have some high gain early arriving reflections which will need to be tracked down with the ETC function. I'm going with the heavy absorption up front approach to try to achieve the RFZ. As far as bass the room is very well behaved.

I have a terrible suckout at 80Hz at the MLP and always have.... The room is 14' wide so most of the seating is at the half wave of the primary width mode which is 80hz..... The only way I know of to treat this is moving all my subs to the midpoints of each opposing wall. This won't be hard to do in the future but its not gonna happen in the short term. Anyone got other ideas to deal with the width mode?

HopefulFred, I really don't know how to determine if the baffle wall is "working" really.... I do have some free field measurements which don't have any baffle at all which were done outside but they are plagued with quite a bit of ground bounce.... I could overlay my in-room measurement with that but IDK how representative that really is....??? Any ideas on how to quantify the performance of the baffle wall?

I will do some more measuring this weekend as I have to re-run Audyssey since the crossover correction. I'll post something in the way of FR this weekend.
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post #548 of 647 Old 08-09-2013, 04:57 AM - Thread Starter
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Here are a couple measurments

Here you can see the corrected crossover response in Blue and the Red is with the polarity of the CD wrong, without measurements I would never have known:

900x900px-LL-aa8506ad_seosphase1.jpeg

This is the center channel mic'd at 2m run full range without any Audyssey, crossover, or EQ.......
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post #549 of 647 Old 08-09-2013, 05:45 AM
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So both of those plots are from measuring outdoors with the speaker on its back, right? No gating, no smoothing? How about windowing?

My understanding is nebulous and rudimentary in terms of the machanics of getting good measurements, but I believe that the key to meaningful measurements at low frequency is in a slow sweep with no gating. Since gating would be required to filter reflections, the measurement needs to be anechoic (free field - outdoors). I don't know how windowing would play into this. And nearfield would miss the point. Does that sound right to you?
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post #550 of 647 Old 08-09-2013, 06:05 AM - Thread Starter
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That was taken after the speaker was installed in the baffle wall. It was actually a quick sweep, the smallest REW will do. Its smoothed 1/6oct and no gating. All I was looking at in this instance was the crossover region of 1.2K which is fairly well represented.

For an absolute 1/2 space measurement of the speaker FR, AFAIK, I would need to measure ground plane below the baffle step frequency and free field above the baffle step frequency and then splice the two together at the baffle step frequency or wherever the speaker loses control of directivity.....

I think my first order of business before I can assess the effectiveness of the baffle wall is to locate and possibly treat the early reflections. This may reveal that the front wall behind the screen wall is the source of the bounce which would indicate that the baffle wall was not containing the energy. Either way the early reflections will interfere with the region that I'm concerned with analyzing so to take a close look at that midbass region, I must get rid of them if I can.......
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post #551 of 647 Old 08-09-2013, 06:44 AM
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I would figure that outdoors would still provide a significant advantage, since the ground is the only surface. Of course all that would get you is a baseline from which to compare in-room measurements.

I'm not immediately confident that you can get adequate absorption in room to generate sufficient resolution for meaningful measurements down to the baffle step. But I'm not experienced here, obviously. And there is a reasonable and strong argument to be made that the FR at the LP is the only response of concern.
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post #552 of 647 Old 08-09-2013, 08:04 AM - Thread Starter
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Heres a pic of the layout:

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post #553 of 647 Old 08-09-2013, 09:02 AM
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I'm not certain of all my calcs, but I think if you can attenuate all the side, ceiling, and floor reflections sufficiently, you're left with a rear wall reflection delayed almost 16msec. Gating at 16msec gives you no room for error and a resolution of 62hz.

That's based on measuring at they LP - direct distance of 10ft and reflected distance of 28ft. From memory the speed of sound is 1130fps. If any of that's wrong, say and we can try again. This is again, as you know, presupposing you can attenuate the other reflections. You could probably get better resolution with a longer gate time by measuring closer, but I'm not sure that's appropriate. (I can't say why it wouldn't be, but I don't know)
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post #554 of 647 Old 08-13-2013, 05:43 PM - Thread Starter
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Integration Update:

I have fully integrated the new SEOS speakers with Audyssey, EQ, Gain structure, Distance Tweaking, and crossover.

Currently I'm running all the mains and surround speakers at a crossover of 70Hz to the subwoofers. I have found favorable integration with most of the subs pushed to the center of the room up front and the IB sub still in back corner(of course).

Still this setup is actually very smooth even without external EQ. Actually I didn't even use external EQ on the main Subs, only on the IB sub in the rear to squash some major peaks.

My results are very good IMO measurement wise and audibly. Very high impact and easily double the dynamics of the last setup of mains.

Graphs?

Here is the average response(Center Channel) across the three main seats 1/6 octave smoothed:



Here is the response(Center Channel) of three main seats overlaid 1/6Oct smoothed:



Here is the average response across the three main seats of the bass response, unsmoothed:

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post #555 of 647 Old 08-23-2013, 04:56 AM - Thread Starter
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OK, Onto the next order(s) of business.

The baffle wall has been working very nice. I measure its performance by the amelioration of the SBIR issues I had. Now my Center channel has a favorable ETC, and I haven't even finished my room treatments yet!!! eek.gif

Here's a shot of the ETC. It has a very early reflection which is either off the headrest next to microphone or between screen and speaker baffle(Illustrated with black arrow). The delay indicates a 6" longer pathlength than the primary sound so those are the only possibilities. Furthermore other than covering the speaker baffle with absorption(which I might do) IDK what can be done about it.






For those not familiar with ETC a brief summary. I'm looking at the immediate 20ms after the primary sound(the x-axis). Sound after this time arrival is late enough to be of less concern when addressing SBIR. We want all the sound in this 20ms window to be attenuated at least 20db. So I highlighted the area of concern in yellow. What we want is no major peaks to jump up out of the yellow.




Before the SEOS and baffle wall I had several reflections up 5-10db out of the(yellow) 20ms window. Therefore I attribute the better SBIR control to both the controlled directivity speakers and the baffle wall doing its job preventing unwanted front wall reflections.

Now the astute will notice I didn't mention the L and R. I havent mentioned them b/c my side wall treatments are not complete or currently adequate. Therefore I have not even evaluated them with ETC yet as they are close enough to the side walls that I'm sure they need further treatment.

This treatment brings me to my next project. Room treatments, Lots of them. Many to be covered with thin reflective coverings so as to only operate in the midbass but several to be true broadband absorbers on the side walls and ceiling.

Oh and also a couple more panels to be added to the baffle wall, especially under the center channel.

Happy Friday People, Do work in your Theaters!!!
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post #556 of 647 Old 08-23-2013, 05:02 AM
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Your demonstrating why it's good to have a baffle wall.

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"Too much is almost enough. Anything in life worth doing is worth overdoing. Moderation is for cowards."
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post #557 of 647 Old 08-23-2013, 05:29 AM
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It's still too soon to make any final judgements, but have you been monitoring decay times during this process? And have you thought about integrating a scattering or diffusing surface to your panels? The pros sure seem to prefer BAD panels (and I forget Quest's name for their hybrid panels - q-sorber?)

Congratulations on your success so far! Get back to work!
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post #558 of 647 Old 08-23-2013, 05:50 AM - Thread Starter
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Hey HF,

Oh, we aint done yet! biggrin.gif

I still have all my panels behind the LP unfaced, which i plan to change. All those behind the LP i will face with plastic or kraft paper to help restore decay balance. Unless ETC shows they need to absorb broadband.

I have been monitoring the decay and i dont want to add much more broadband to the room. Most will need to be faced to keep room life.

I have contemplated diffusers especially behind the LP but honestly they are just too costly. Furthermore my room is very small at 14x21 and the diffuser locations would be 4-6ft from the listeners ears which has impact on the diffusers effectiveness.

I looked at building DIY QRDs and if i went with serious diffusion thats prob what id do. More practically ill probably just add some polys around the room in the end. I know they are not proper diffusers but are better than blank flat walls!
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post #559 of 647 Old 08-23-2013, 06:10 AM
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Ever since I realized how simple it could be, I haven't been able to shake the idea of doing what Mr.Tim did. http://www.avsforum.com/t/1426519/mr-tims-15x27-theater/270#post_23207692

Especially for the panels nearest the SEOS, the only absorption of interest should be below 500-600hz, right?
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post #560 of 647 Old 08-23-2013, 06:54 AM
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Thanks for the plain englisg summary of ETC and recommended time delays. I haven't measured that yet (too busy watching mov... er testing the system).

I will give that a shot this weekend. Like you, I don't have the treatment on the walls yet as the hvac supply hasn't gotten my 2" fiberglass in yet. Curious to see how the rear diffuser works out.

Tim
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post #561 of 647 Old 08-23-2013, 08:03 AM - Thread Starter
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Quote:
Originally Posted by HopefulFred View Post

Ever since I realized how simple it could be, I haven't been able to shake the idea of doing what Mr.Tim did. http://www.avsforum.com/t/1426519/mr-tims-15x27-theater/270#post_23207692

Especially for the panels nearest the SEOS, the only absorption of interest should be below 500-600hz, right?

Very good Sir! I did think about the closest panel to the SEOSs only needing midbass absorption. My plan is two sets of 3 2'x4' panels on each side wall. However the other 5 panels on each side wall will need to be broadband due to the large toe in I use with the waveguides.....

Here is a model showing the expected panel placements



Here is a shot illustrating the expected dispersion of the horn HF energy. While the first panel or two doesn't see any HF energy the rest surely will.



I'm thinking I'll definitely face the first panel.....
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post #562 of 647 Old 08-23-2013, 10:24 AM
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Quote:
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I'm thinking I'll definitely face the first panel.....

Or, you could put 6" strips of facing, as Quest does. That way it's not an all-or-nothing proposition and you can vary the placement of the strips to exactly what you need.
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post #563 of 647 Old 08-23-2013, 10:39 AM
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It would be interesting to see the reflected signal strength (via ETC) for an open broadband absorber compared to a variety of other facings. You may find that the gain is still -20dB even with some reflective cover in place.
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post #564 of 647 Old 08-26-2013, 11:33 AM
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Quote:
Originally Posted by HopefulFred View Post

SNIP... The pros sure seem to prefer BAD panels (and I forget Quest's name for their hybrid panels - q-sorber?) SNIP...
Quote:
Originally Posted by NicksHitachi View Post

SNIP.....

I have contemplated diffusers especially behind the LP but honestly they are just too costly. Furthermore my room is very small at 14x21 and the diffuser locations would be 4-6ft from the listeners ears which has impact on the diffusers effectiveness.

I looked at building DIY QRDs and if i went with serious diffusion thats prob what id do. More practically ill probably just add some polys around the room in the end. I know they are not proper diffusers but are better than blank flat walls!

An alternative to the slat type of hybrid amplitude diffuser would be the "BAD" panels as HF mentioned. again the proximity to the diffuser is far more forgiving than the temporal type diffusion from the QRD's and better suited for our smaller rooms particularly on the side walls.

They could be DIY'd extremely cheap once you got past the tedium of drilling, although several panels could be drilled at once.

And since they are made from 1/8" HDF or masonite, the panels could also be used as the surface of your polys for additional diffusion.

Several threads on Gearslutz discuss in greater detail.. here are links to a couple of posts for a calculator and an actual pattern for the binary sequence.

Spreadsheet

http://www.gearslutz.com/board/6911715-post69.html

Pattern and inverse pattern

http://www.gearslutz.com/board/9251944-post105.html

The cost of the quest products are tough on the digestive system, particularly the perfsorber. However there are significant differences between the design/construction of the perfsorber compared to just the binary grid used to face the BAD panel absorbers.

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post #565 of 647 Old 08-27-2013, 02:50 AM
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Quote:
Originally Posted by KNKKNK View Post

The cost of the quest products are tough on the digestive system, particularly the perfsorber. However there are significant differences between the design/construction of the perfsorber compared to just the binary grid used to face the BAD panel absorbers.

Truer words may never have been uttered. Even for my humble little room the cost of Quest was well over $3k.

Regarding your comment above, what do you see as the main differences aside from thickness of the panel, difference in hole pattern and the use of 1/8" hardboard on the facing of the BAD panel?? Beyond these differences they seem very similar as both utilize membranes over rigid fiberglass for additional absorption / reflection of different frequencies.

It would be interesting to know if anyone has reverse-engineered the Quest Perf-sorber in the same way the RPG panel has been deconstructed...
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post #566 of 647 Old 08-27-2013, 04:28 AM - Thread Starter
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Quote:
Originally Posted by KNKKNK View Post

Quote:
Originally Posted by HopefulFred View Post

SNIP... The pros sure seem to prefer BAD panels (and I forget Quest's name for their hybrid panels - q-sorber?) SNIP...
Quote:
Originally Posted by NicksHitachi View Post

SNIP.....

I have contemplated diffusers especially behind the LP but honestly they are just too costly. Furthermore my room is very small at 14x21 and the diffuser locations would be 4-6ft from the listeners ears which has impact on the diffusers effectiveness.

I looked at building DIY QRDs and if i went with serious diffusion thats prob what id do. More practically ill probably just add some polys around the room in the end. I know they are not proper diffusers but are better than blank flat walls!

An alternative to the slat type of hybrid amplitude diffuser would be the "BAD" panels as HF mentioned. again the proximity to the diffuser is far more forgiving than the temporal type diffusion from the QRD's and better suited for our smaller rooms particularly on the side walls.

They could be DIY'd extremely cheap once you got past the tedium of drilling, although several panels could be drilled at once.

And since they are made from 1/8" HDF or masonite, the panels could also be used as the surface of your polys for additional diffusion.

Several threads on Gearslutz discuss in greater detail.. here are links to a couple of posts for a calculator and an actual pattern for the binary sequence.

Spreadsheet

http://www.gearslutz.com/board/6911715-post69.html

Pattern and inverse pattern

http://www.gearslutz.com/board/9251944-post105.html

The cost of the quest products are tough on the digestive system, particularly the perfsorber. However there are significant differences between the design/construction of the perfsorber compared to just the binary grid used to face the BAD panel absorbers.

Brad

Thanks for those links! How is the best way to go about getting the pattern onto a template panel? Take the image to a print shop and get a 2x4 printout?

This looks promising if getting the template panel is not too much hassle.
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post #567 of 647 Old 08-27-2013, 08:49 AM
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Quote:
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Thanks for those links! How is the best way to go about getting the pattern onto a template panel? Take the image to a print shop and get a 2x4 printout?

This looks promising if getting the template panel is not too much hassle.

Some of the kinkos (at least in this area) have large format printers ie.. 24" x 36". You could take the PDF Files and have them scale and print to 24" x 24" for around 5$ a sheet. You would probably want to produce both the standard and inverse patterns. alternating them will help reduce any potential effects of lobing.

Then take the print and overlay a sheet of 1/8" HDF or masonite. I would probably just take a center punch and go around the overlay and quickly punch the hole centers locations.

I think once you had the centerlines marked on your top sheet you could stack and clamp several sheets together for drilling. also something like an Irwin Speedbor may work better than a conventional drill. Afterwards you could use any of these sheets as a template for additional grids.


RPG is also rumored to sell just the grating for ~ $50, that could be used as your first template, but my understanding is that they only sell through acoustical designers etc. so I'd probably just go the route described above.

This post shows a ceiling of binary gratings purchased from RPG over regular insulation http://www.avsforum.com/t/1351987/theater-build-mikes-money-pit/30#post_21123803



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post #568 of 647 Old 08-27-2013, 10:10 AM
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I've used the large format printers at Kinko's and was not impressed with their ability to maintain geometry. I was working with a weird original, so maybe the problem was elsewhere in the chain, but I'd lay it out by hand. Maybe that's just me doing things the hard way.
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post #569 of 647 Old 08-27-2013, 10:55 AM
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Quote:
Originally Posted by HopefulFred View Post

I've used the large format printers at Kinko's and was not impressed with their ability to maintain geometry. I was working with a weird original, so maybe the problem was elsewhere in the chain, but I'd lay it out by hand. Maybe that's just me doing things the hard way.

interesting, I wonder if you could get them to print one out as a test, and you could double check it. Just let them know up front you have some doubts about their accuracy and see if they're willing to let you check it before you buy it.

Dude, are you made of leprechauns? Cause that was awesome!

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post #570 of 647 Old 08-31-2013, 07:52 AM
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Originally Posted by TMcG View Post

Sweet progress Nick! I've been quietly lurking (and learning) over in the SEOS threads and following along with your build questions. I really, really like the fact you have a curved back speaker similar to B&W's Nautilus line (and Revel, Paradigm, etc.). Did you come up with this cut plan or was that something I missed? Either way your woodworking is really great.

To be honest, I have never seen an instance where someone had baffle panels - only full baffle walls. Procella has a great pdf guide to building baffle walls on their website located here: http://www.procella.citymax.com/f/Procella_System_Design_&_Installation_v2.5_Web.pdf Baffle wall construction starts on page 19. Generally speaking the more mass on the front of the wall the better, so they recommend one layer of 3/4" MDF glued and screwed, plus two layers of 5/8" drywall with Green Glue dampening between the layers. Then on top of the drywall two layers of 1" Linacoustic (or similar) separated by a layer of 3 mil poly. The "cubbies" for the speakers should be constructed from either one or two layers of 3/4" MDF (with Green Glue if you go the second layer) and be as near-net shape to the speaker as possible. Fill any voids with insulation. To make the boxes removable at a later date, make the box deep enough so the front edges are flush with the double layer of 5/8" drywall and then cover the leading edge with the Linacoustic.

As to speaker height, Procella recommends the "acoustic center" to be at 5/8 up the height of the viewable screen (i.e. just slightly above center). Given the similar design between SEOS and Procella I would imagine your speakers would have a similar "acoustic center".

For the 2pi calculations....I have NFI but am anxious to learn what you find out!!! biggrin.gif

By the way, do you mind sharing your parts/material list along with the total cost per completed speaker? I know the SEOS things are like $35, but it is the compression driver and woofer selection that can really drive the cost skyward. Thanks and keep up the great work.


Oh....and I am very glad to see you still have the beers handy during production!!!

http://www.procella.citymax.com/f/Procella_System_Design_&_Installation_v2.5_Web.pdf

Thanks for great link^

Does a baffle panel work as well as a baffle wall ? Anyone have thoughts on the differences ?

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"Too much is almost enough. Anything in life worth doing is worth overdoing. Moderation is for cowards."
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