DecWare Corner Horns

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I haven't made a decision about building them yet - the issue is making sure I have a corner to use one in before committing to it.
The corner I have available isn't huge, there's a window near the corner, I probably have 18 inches of space.

The DecWare White Paper said something about these speakers needing to be placed in a corner and the sides were intentionally left off so they had to be used in a corner to work, but some idiot would eventually put them in the middle of a room.
Steve was probably thinking of me when he wrote it.
I built one speaker as a test when I had one corner available.
I liked it a lot, so I built a second speaker and while building a stub wall along the long wall of my shop, I decided to use the speakers. I had a couple of half sheets of 5/8 inch drywall awaiting the framework and I tacked it on one of the open sides of the second speaker, the other side was against a wall. It worked great. I then added a second 4x4foot piece to the other side and faced it out into the room. It also sounded great, maybe better than the first speaker in the corner in that the Fostex's were no longer firing at a 45 degree angle.
Whatever bass the horn lost by not being in a corner was equalized by the extra side wings now added, turning a 14 square foot mouth into a 24 square foot mouth.
If one only has a single good corner and a blank wall, one can add a side to the second speaker, or set a bookcase or file cabinet against it. The speaker doesn't know that its not a wall.
 
Do you have Partworks with your Shopbot? If so, use the Create Fluting Toolpath and in my case, the same 1/4" flat endmill bit as I cut the parts out with.
I can't find a photo or scrap piece right now of the results but would be happy to send you a Partworks file of how I do this...
Hi Tom, No need to send a Partswork file, Your instructions are easy to understand. Next time I need to cut a strange angled bevel, I'll give it a try.
After you receive your plans and if you decide to built the horns, let me know and I'll send you my Partswork files for the horizontal pieces and if you are so inclined, you can send your files for the vertical pieces.
If we can do these on the ShopBots, life will definitely be a lot less dusty.
Dennis
 
If you decide to build them, is there any chance you would build an extra pair for sale or sell the parts as a flat pack?

Hi, were you asking me ?

I'm not sure, but I suspect the plans from Decware prohibit anyone from building them for sale without a license from Decware.
 
I got the plans, had a couple rainy days, and did a quick model in Google Sketchup. Rather than rounded in the front I simplified it.

Next step is to deconstruct the model making all the pieces larger to embed 1/4" into adjacent pieces and cut 1/4" channels to accept those pieces.

After that each piece has to be exported into the CNC software for toolpathing the weird angles and cutting it all out. Since this thing is symmetrical top to bottom and side to side I will make a mockup of 1/4 section of this thing to verify fitup.
 

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Well I certainly appreciate your confidence in my abilities! :cool:

Actually, it looks a pretty challenging build and I doubt I would want to commit so much of my time to making several of them. I plan to make one. I am looking to 'fill my house with sound' and my experience to date with stereo tells me I'd be wasting my time building a pair. Mono is where I'm heading with this idea for now. This means I only need to make use of one corner in my house. And that greatly simplifies the implementation because then it no longer depends so much on finding two available corners that are both suitable and both the right distance apart and dealing with sound stage issues etc.

The main floor of my house is shared with my family. It means a dedicated stereo set up for me, with everything in the right place and enough peace and quiet to make proper use of it is - futile. We get good use out of my DIY amps and speakers but it's always based on them being located where they are out of the way and the sound is allowed to float round the main floor of the house for all to enjoy. Even our mono kitchen radio gets good use. I see a lot of potential for a mono horn set up. And I get to make one cracker of a mono tube amp since I can then spend twice as much on one channel compared with a stereo.
 
Build with Sides?

Putting sides on adds alot of support for the flare wings. I doubt any internal bracing would be required with sides. In my opinion, based on Dennis's tests above, that adding sides would not have any change on the sound.

Also I show one (getting even larger) with extended sides. Dennis is this basically what you did?
 

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Putting sides on adds alot of support for the flare wings. I doubt any internal bracing would be required with sides. In my opinion, based on Dennis's tests above, that adding sides would not have any change on the sound.
Also I show one (getting even larger) with extended sides. Dennis is this basically what you did?
Hi Tom,
This is what I did.
DecHorns with wings.jpg
After I nailed the Sheetrock to the walls, I used a couple of pieces of 3/4" mdf (recognize the spoil boards from the ShopBot?). It provided bass about equal to the corner placement. These were used for a few days while the drywall mud and paint dried.
I am not a golden Ear audiophile. I cannot hear the enormous improvement in sound stage that comes from changing speaker wire. Nor can I observe a tremendous improvement in frequency response when plugging into a hospital grade receptacle. I built speakers for sale for a number of years and modified them many times. I could hear the modifications, but often could not tell it they were better or not. I really do not know what Alison Krause actually sounds like, so when I read that doing certain changes now make her sound perfectly lifelike, I just shrug. So take my observations with a grain of salt again.

Without corner placement and without wings, the Fostex's sound sort of like Fostex's in a ill designed cabinet. Sort of screechy without base. With the wings and against a wall verses corner placement, the speakers both sound very good but a bit different from each other. With the Fostex pointing straight at you instead of usually off axis, highs and mids are more pronounced. I don't know if that is good or bad, just different.

I stole one of your drawings because it shows the innards of the horns better than anything else that I have found. It has now been added to my show and tell of how these horns are made. Thanks.

I really like the drawings of the extended wings. I may have to make a set of wing extensions just because they look so neat. Technically, they should angle slightly outward to provide a properly expanding horn. In reality, I doubt that one could hear the difference. The JBL guys once told me that most record companies cut the recording off at 50 Hz because there is little musical information below that and mostly just turntable rumble.

I did not use any bracing on the wings. The speakers were getting heavy so I avoided the bracing and dropped the wings down to 3/8 ply because I had some. I also just hot glued the wings on so I could get them off if I wanted to move the speakers down into the basement. I have had no problems at all with rattles or resonances. I am pretty sure that they are overbuilt by a factor of a lot. I also put the tops and bottoms on with gaskets and screws so I could get back in them if I needed to make changes (like trying out the 4 speaker arrangement). Trust me, they are pretty awkward to move when fully assembled.

There is a set of these being built not far from here. They should be finished next week. I am looking forward to hearing them in a household setting.

Keep us informed of your progress.

Dennis
 
A few things I need to mention about my version of this:

1. I simplified the front final flare so no "fussy rounding" would be necessary. It will add volume to the space behind the driver but I will calculate the difference and simply add volume later (and remove it if detrimental for some reason).

2. I eliminated the option of a removable front baffle as I have no intention to try internal 5 inch drivers.

3. I eliminated the reflectors at the first bend for this reason as stated in the White Paper -- "Parts P & Q are actually panels that set the proper angle for the bend in the horn flare. These angles will reflect high frequencies that are too short to make the bend and thus increase the bandwidth of the flare to 4500 Hz when four 5 inch full range drivers are used on the inside of the cabinet instead of the single 6 inch front mounted arrangement." These could easily be added later if necessary.

4. I intend to build these with enclosed sides but NOT extended out past beyond the flares. That allows the possibility of easily attaching extended wings later if not used in a corner -- "hinged" extended wings?

5. It appears I can construct my version with 13 different parts (not including mirrored parts) instead of 18 different parts as shown in the plans.

Finally, creating the 3D model really helped visualizing this. I know it would nowhere near have been as easy to model this using the plans alone. "In progress" pics found on the internet helped immensely.

Dennis, I look forward to your impressions of the new set being built. Also, please post pics if you are able.
 
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Below are pics of how I numbered the pieces in my trial-for-fitup "quarter section" of the horn using the same 3/4" plywood as I will be using for the final horns.

Next shown is the full horn base piece with the 1/4" channels for placing the pieces into.

Last two pics are 3D model (looking underneath) part 11 and then the rendering of it cut out in plywood. Machining time will take about half an hour for this piece due to the miters.

It may be awhile before I get a chance to cut these pieces and assemble this "quarter section" due to other priorities. The "quarter section" will make a cool cut-away model.
 

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Which drivers are recommended for the 4-speaker arrangement ?
There weren't any drivers recommended. The White Paper is silent as to the 4 speaker details. I would have liked to have seen even a rudimentary frequency curve for the 4 speaker system or maybe a description of the issues that Steve mentioned.
I am curious as to what a four speaker true horn system would sound like but not enough to spend the time and money to find out.
There was mention that the four speaker system produced too much bass for home use. so what would happen with a 2 speaker system?
Eventually the satisfaction of my curiosity will win out and I will build a single test speaker and install two five inch bass/mid speakers in it in front loaded horn configuration if someone else doesn't do it first.
Madisound has several 5 inch mid/bass speakers with Qts less than 0.3 and Fs in the right range. Only problem with the four speaker system is that the speakers cost in the $50 each range and all eight will cost $400 plus cabinets plus tweeters.
I am not sure that I have that much curiosity so I will just make a single test speaker with 2 drivers. I already have a bucket of tweeters.
I am $200 curious.
Will write a report when I get to it.
Dennis
 
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Tom:

ambitious project, but I'd suggest you contact Steve regarding your plans to "simplify the fussy rounding" in front flares - regardless of his often creative descriptions, there may be some very good acoustic reasons to retain them.

also, IINM the special custom modded driver that Steve recommends for this design is based on the FE166E ( now En)


Dennis:

clearly the added side panels free this design from the constraint of corner placement - did you find much of a decrease in bass extension?
 
Tom:

ambitious project, but I'd suggest you contact Steve regarding your plans to "simplify the fussy rounding" in front flares - regardless of his often creative descriptions, there may be some very good acoustic reasons to retain them.

also, IINM the special custom modded driver that Steve recommends for this design is based on the FE166E ( now En)

Dennis
clearly the added side panels free this design from the constraint of corner placement - did you find much of a decrease in bass extension?

Readng the White Paper, it appears that Steve went through all the calcs for a front loaded horn enclosure using 4- 5 inch speakers buried in the cabinet. For some undisclosed reason, he sort of abandoned this configuration and stuck a front facing Foxtex in the rear cavity of this horn and converted it to a ported bass reflex speaker with a megaphone on the port.
It worked serendipitously well, but not likely due to any special engineering of the cabinet fronts.
Most of the sounds come from the front facing Fostex and it works about as well as any other Fostex in a box. Most Fostex's are put in a box with square fronts and this one will work about as well as the others with a flat face.
I used a Fostex 166en because it superseded the 166e. I do not believe that Steve recommended it and I have never seen any recommendations for the 4-5 inch speakers in the original cabinet. In theory, they need a a frequency response past 4500, a low Qts and a Fs at least 25% about the 40 to 50 Hz cut off frequency.
Steve wrote that he only built the prototype and it sounds like he never experimented with mods at all. He may have hit a home run right out of the box or there may be more to be found.
We will see.

The temporary side panels provided enough bass that I was satisfied with the system while I completed a corner. The two configurations sound different, but it is not in the lower frequencies. Room placement and axial response probably are the reason. Remember, in back loaded horn configuration, only frequencies below 150 Hz are affected.
There is a difference, but I do not know if there is an improvement.

Dennis
 
A year has passed and other priorities kept cropping up. Among other things I did build a Mileva and a MLTL with the FE167en's.

That said, it sounds like (but I cannot find officially) that the FE166e is the preferred speaker for the Decware Corner Horn.

Has anyone else made progress here or on any related projects to this?
 
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