Ever think of building a Cornu Spiral horn? Now you can!

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Endia, 4" car speakers might be just the thing. Good idea!

Whilst searching for the Fountek drivers I'm playing a little Audience A3 fullrange. Fs is 70 Hz. Not bad. Maybe sounds more balanced than the Vifa.
The cool think is to start the driver out playing outside the box and then lower it into place. The gain in bass is very audible. Goes from tinny to full.


I have wondered about Pioneer a878 3.5 inch coax's in the cornu.
4 ohm, 60 hz, with zing from a tweeter.
 
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The Audience A3 needed a little cutting for the frame, but not much. I'm holding the drivers in the gaffers tape. I put clear packing tape on the face of the foam core, and stick the gaffer tape to that. Seems to seal well and doesn't lift the paper.
 
Well, a belated congratulations Switters! :cheers:
:)
Have you had a chance to put stuffing in? I think the frs8m can work well in this too.

Thanks. No belated but earlier :p I've yet to finish the baffle, maybe veneering it. It always take weeks or months to me to finish something in my free time.

Yes, now there is some stuffing in the chamber behind the driver and in the first segment of the horn. I've also repassed with glue the ends of the horns, PVA glue isn't the best to fix the back on the spirals. Next time I'll use a glue that is more dense.
 
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So far, maybe the A3. But I have only one and they were $170 a piece retail - crazy! I got mine as a sample. The Vifa is a close second. With some work getting the low end under control, it could be very nice.

I'm not very experienced with back horns, so don't know if they work like front loaded horns. If they do, then it seems to me that a cutoff of 100Hz is about right for the 80" mouth size of the 20" Cornu.
 
I've had a chance to do some listening. The thrill is gone, the shine has worn off and I no longer have the ****s and giggles with these babies so let's get serious. Here are some of my thoughts. You already know what xrk, me and everyone else knows about the good side of these things now I want to talk about the not-so-good.

I want to start by saying, I can only describe the boxes you guys saw me build and the Fostex/planet10 drivers so it would be nice to hear your stories as well.

1. I don't like the sound of these in the nearfield. I like to be at least 10 feet away and...

2. After the glitter of the bass wears off, I find I prefer these over damped to allow the mids and highs to come through and then to position myself where the room nodes increase the bass to my tastes. This limits the listening position.

#1 is natural. That happens with most larger speakers but I am surprised with such a small driver. Perhaps this is actually credit due to the cabinet.

#2 may be a result of the driver used. I thought Fostex drivers would be ideal for this box. I mean Tab A and Slot A perfect. Maybe they need to be in a larger horn so I can enjoy the bass more

Interested in your thoughts.

EDIT August 26, 2013:

I had a chance to listen to these in the great outdoors and I am going to retract the "glitters wearing off" stuff. These are a great speaker and they gave others the same experience I was having so disregard that **** I said about them being not so good.
 
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I've had a chance to do some listening. The thrill is gone, the shine has worn off and I no longer have the ****s and giggles with these babies so let's get serious. Here are some of my thoughts. You already know what xrk, me and everyone else knows about the good side of these things now I want to talk about the not-so-good.

I want to start by saying, I can only describe the boxes you guys saw me build and the Fostex/planet10 drivers so it would be nice to hear your stories as well.

1. I don't like the sound of these in the nearfield. I like to be at least 10 feet away and...

2. After the glitter of the bass wears off, I find I prefer these over damped to allow the mids and highs to come through and then to position myself where the room nodes increase the bass to my tastes. This limits the listening position.

#1 is natural. That happens with most larger speakers but I am surprised with such a small driver. Perhaps this is actually credit due to the cabinet.

#2 may be a result of the driver used. I thought Fostex drivers would be ideal for this box. I mean Tab A and Slot A perfect. Maybe they need to be in a larger horn so I can enjoy the bass more

Interested in your thoughts.

Cornucopya Fans and Cal:

For me, the thrill is still there and I am still surprised by how good my old CD's sound as I put new ones through. It is a real treat to listen to them still. Also, I listen to my micro 14 inchers all day long upstairs as background music. They are very rich sounding for 2 inch drivers running on less than a watt. So, for me, I am still a happy camper. :D

I agree with number 1 and like to be at least 8 ft away and it still sounds great at 18 ft away, I think it allows the bass from the edges to blend with the room and integrate with the main output from the driver. Like you, I feel that the sound is like as if it is coming from a very large speaker that you would not want to be close to.

I am using a different driver and a smaller cabinet, so I think that may be the reason I don't have too much bass and the mids and highs from the Vifa, in my opinion, are outstanding. The vocals come through unlike anything I have heard before with perfect imaging and clarity yet the soundstage is very wide. Furthermore, the off axis response is excellent and I feel that there is a very wide sweet spot as long as you are back at least 8 ft. Bob is also using the Vifa in a slightly larger cabinet of 24 in and that still seems to work.

I think that with the Cornu, one wants to be careful not to use a driver with too much bass to start with, and not to make it too big. The increased size lowers the tuning frequency and increases the bass gain since it grows the horn mouth and hence, expansion ratio. The expansion ratio of these Cornu's range from 24 to 30 depending on the size. Think about that, most rectangular BLH designs, you are doing good when you can get 10 expansion from throat to mouth. I think that may mean that the bass is going to be up to 3x more than traditional BLH designs.

So I think one thing tomtry is to get a driver with a hot HF end and not too much bass, and not to make it bigger than 28 in (possibly smaller might be better).

Have a safe and happy holidays you all. Stay warm.

Xrk971
 
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Since many of you are out having a good time or maybe in bed, and my honey and I have an early flight out in the morning... I'll tell you what happened.

I stayed well away from the speakers. I put on the Jimmy Buffett album Banana Wind.

I turned it up till the drivers actually moved a little, maybe 5 or 10 watts. I turned my back and told myself "Cal you're listening to a 125mm driver."

'nuff said. Smile has returned to my face.

See you guys in a week. Merry Christmas to all. Check in when I can.
 
Switters,
So how does it sound to you now that you have stuffing? What's your impression? Good, great, amazing, or maybe ok only? We love feedback of your listening experience and type of music you have listened to on it. And would you recommend the FR88 to anyone else?
Thanks
Xrk971

Well, now I have to find all the right and proper english words I'm missing to describe perceptions and sensations. This is, for me, a more difficult job than build this loudspeakers :p
Disclaimer: this is about the 50x50 cm (20x20 in) box, I placed them against the wall but I have yet to position and hang it to the wall. Also, I don't have a high-end reference setup to compare to, so this are just my first impressions.

Low frequencies are really there. Even at very very low volume.
On the other hand it seems to me that LF are not so controlled as with a closed box (but then, in a closed box, a 3" driver would produce a lot less LF), I think this is because 1) the little delay between direct and back emission, 2) the open and big volume of the box doesn't load and "hold" the driver cone like a closed box. But I'm not an expert and this are only my guessing.
The fact that LF aren't tight controlled adds "warm" and perspective to some tracks (voice+double bass) and I like it a lot.
I've listened Massive Attack (Angel, Inertia creeps), Pink Floyd (Time, Shine on...), Dead Can Dance (Bylar, Yulunga), Ella and Louis, Nirvana, Nada Trio, and also some DJ's electronic dance.
Without stuffing they were too booming, also because, I suspect, the glue didn't sealed perfectly the box, after stuffing and some more glue there is a lot less booming. This was evident in particular with two tracks, Bylar (Dead Can Dance) and Brother Wolf Sister Moon (The Cult), that sounded really "strange" before the treatment. Now they sound a lot better, but in Bylar the mid-highs of the femal voice are a little "back" losing a bit of presence. The male voice instead gained in presence.

In conclusion, maybe they are not the most balanced loudspeaker but I (and also other people) like how they sound, I will try other drivers on this box and will build the big version (70x70 cm).
So... I'm very happy... thanks for the idea xrk971 ;)

PS: I can't recommend the FR88 because I never listen to it :) Regarding the FE85, I wish to try other drivers to make a comparison.
 
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Switters,
Thank you for the listening impressions. Your English was perfect. Sorry, I thought you were using the FR88, but it sounds like the FE85 works for you. I totally agree that the presence of the bass is there even at very low volumes. This is what makes them great for background music as you often don't want the volume loud but the sound is still full. It sounds like you tried it on quite a bit of rock music and it worked for you.
I am glad you like them. :)