Foam Core Board Speaker Enclosures?

If i was looking to build a set of reference speakers for producing on im presuming foamcore isn't the material to be using?

Im thinking ideally i need similar response characteristics to what the produced music will be played on. So any ideas how id go scaling down a set of four ss15 subs? I have a set of four 6inch car audio drivers id be wanting to use Vdo Dayton drivers from a split system.
 
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If i was looking to build a set of reference speakers for producing on im presuming foamcore isn't the material to be using?

Im thinking ideally i need similar response characteristics to what the produced music will be played on. So any ideas how id go scaling down a set of four ss15 subs? I have a set of four 6inch car audio drivers id be wanting to use Vdo Dayton drivers from a split system.

Are you still looking to build a fullrange studio monitor or were you looking for a subwoofer?

There is a whole forum on subwoofer design if that is what you are after, we are strictly fullrange here. I don't think foam core would be good for subs as there would be significant spl difference between inside and outside of cabinet with amount of air that subs move using long stroke. You really want a stiff, dead sounding cab, like MDF... :(

And as much as I love DIY, I listened to a pair of biamplified active crossover studio reference monitors yesterday with 5 inch drivers and 1 inch silk dome tweeters in a BR ported cabinet with waveguidefor tweeter, and they sounded really good. I am not sure you can do much better once you get parts to put together yourself (price - these were $200/pair, or performance). In building complex horn cabinets, that is where the diy'er has an advantage and can make something better than commercially available stuff at a reasonable price.
 
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Im not looking to build a sub. More a full range speaker better coax or whatever but it needs to have a similar sound to the horns i play on. Its gonna make it hard coz i done have any specs on any of the drivers i have here.
I've got some Sony 7inch woofers , sharp 6inch , jvc 5inch inch, kenwood 6inch,VDO 6inch and three set of 6x9 car speakers. None of which i have specs on.
Id have to sit and listen to them all decide which i like the sound of then measure them out. Its something ive never done tho... So not sure how reliable that would be.
Any suggestions?
 
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Measuring them requires equipment software and know how. I'm sure it can be done but not the most cost effective solution considering how many excellent FR drivers are available for a reasonable price. Many of the Tang Bands, Mark Audio, Fostex, etc. are used and would be recommended by the folks in this forum. If you are serious about a good reference monitor, I would not mess with unknown drivers. If you are building for fun and want to see what an old driver without specs can do then use them. I think Planet10 would probably be able to give you a recommendation on a driver that works for what you need. Personally, I have been eyeing the MA CHR 70 as a good combo of price and performance. I would also look at the TB bamboo paper cone driver too. The Fostex are great if you want high efficiency but don't have much stroke for punchy bass which is what you are after I think. For best value in terms of sound quality and bang for the buck, I really like the Vifa tc9fd
- but you probably figured that out already. If you can go up in price I think the MA Alpair 7's are promising. I hope this helps.
 
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Klampy,
When you say it has to sound similar to the horns you play on, are you referring to the compression loaded driver horns used for rock band type stage speaker boxes? If that is the sound you are after, I have to say that foam core can be used to make a horn just like those in the speakers you are talking about (curves and all on a tractrix) and mount it to a compression driver. Is that what you are talking about?
Xrk971
 
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Lol. :D :D :D




It's the same junky stuff from the dollar store, just black. But it is easy to work with! I actually decided not to use the sheet of 'good' foamcore because it will be much harder to bend.

Also, a bit of PVA in the scores once the hot glue is set is making the curves much more solid.




I don't have a face on it. I need a tube of liquid nails.

Why not PVA the top face on, liquid nails may not have nice clear color like white glue and may mess with your 'nice curves' :). Or use the Gorilla glue that Cochleus recommends - sounds perfect as it is a gap filler, dries clear, and sets in about 15 minutes which is enough time to work.
 
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I finally got to see/listen to your creation on video (had to use my regular computer as the android tablet was unable to see the video - probably a lack of flash support). Your foam core quad driver single mouth horn box ROCKS! :nod::bigeyes::cheers: (although the range of your phone's microphone is not doing it justice) Very cool. More of us should upload vids or mp3's of our speakers cranking out the tunes. I have been meaning to do the same with a mp3 recorder (it has some decent XY condensor mics that should give sense of bass/highs and stereo separation). Very nice job and it looks very clean and professional actually. :cool:
 
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...why I am asking is that I would like to see the proof that the spiral inside is actually doing something
that whole box is quite big itself for small fullrange driver, maybe it would sound the same in the box of the same size
if someone could measure fr response of the spiral horn, and compare it to the fr response of closed box of thesame size, that would make me believe (and even embark on making it, but not before)
 
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I have not gone thrue 60 pages of this thread...are there and frequency response measurements in this thread?

(I mean no desrespect, I just want to see facts)

That would be great if someone performs a measurement of their Cornucopya after they build it. I don't have the equipment to do so, and most others are still in construction stages - except for Cal. (Cal - do you have means to do a measurement?) :D

Bring on your microphones and tone generators! It would be great if we can confirm Don Hills' model - which shows some serious dips and peaks. But to my untrained ears, my 20 inch spiral horns sound great with the TC9FD drivers mounted about 7 feet apart on the short wall at 4 ft height. The room dimensions are about 18 ft x 30 ft x 8 ft tall. I think any simulation needs to account for the room walls and ceiling/floors as the reflected sounds from the edges of the spiral are critical to the character of this cabinet.
 
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...why I am asking is that I would like to see the proof that the spiral inside is actually doing something
that whole box is quite big itself for small fullrange driver, maybe it would sound the same in the box of the same size
if someone could measure fr response of the spiral horn, and compare it to the fr response of closed box of thesame size, that would make me believe (and even embark on making it, but not before)

Adason,

The spiral definitely has a PROFOUND effect on the sound. My initial pre-conceived notion was that it would not work because the box is so small, flat, and open - it is all channels and open air to the outside with no real containment except for front and back. Furthermore, after I made the box out of foamcore, well, it resembled a pizza box literally in feel (weight) and dimensions, further prejudicing me to thinking it would not work. However, like I said, I was blown away by the sound quality when I turned it on for the first time. I have Cal to back me up at this point, but I believe several others are close to finishing theirs.

When I place my ears next to the output horns on the edges, I can definitely hear the low and mid bass coming through. There is also some passive output from the front panel as a radiator. The edge outputs when reflected off the ceiling, floor, walls, integrate with the direct radiation from the drivers combine to reach your ears in a way that is different from any other cabinet I have ever heard.

I think you are right for asking for facts to back things up, but an SPL vs freq measurement will not give you the sense of the ambiance that the Cornucopyas provide when you listen to them in person. I don't think the Cornu's are known for faithfully reproducing music without coloration - they don't claim to be monitors by any stretch - and if you read the detailed 6 Moons review, it confirms this. What they do have is an almost ethereal presence and spacious sound stage with a very wide sweet spot.

If you have a few days time, some cheap foam core boards, a razor, and hot glue... give it a try. :)

In response to your proposal of comparing with sealed box of similar size: I may just do this - a 20 x 20 x 2.38 in Cornucopya is the same as a 5 in wide x 16 in tall x 12 in deep box which is simple enough to make. I can tell you right away that without at least a BR port, the regular box is already handicapped. I don't have measurement tools but can record with a high quality mic to mp3.
 
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I was thinking the same thing, and in fact, have a BLH box that I built that is about same dimensions as dummy box (5 x 15 x 10) but of course, it has channels and horn internally even if I were to seal it. However, if Adason is satisfied with simply covering output ports on Cornucopya, I can easily do that and record some sounds. I expect it will sound terrible...
 
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Adason,
But isn't your question really aimed at how much of a difference in sound comes from the spiral horn rather than whether or not a sealed box enclosure of same size sounds better or worse? The internal channels will have some effect but that has to be re-radiated back out the driver. Granted, there is some sound come from vibrations on the flat front baffle. The covering up the horn mouths is much easier than building a foam box which really would not have further use.
Regards,
Xrk971