First impression...
Not the end all but WOW!
Awesome! That was how I felt when I first listened. What kind of music are you testing it out with? I can only imagine how much better yours sound given the larger full size cabinet, and the tricked out drivers.
I was right when I said you were days away from a first sound...
Does this put to rest the myth that you need to use plywood or mdf for speaker to sound fantastic?
Congrats again!
Thanks to you xrk. I've mentioned it before but it bears repeating. If it weren't for you, this wouldn't be happening. I have thought about that horn for years but always dismissed it. Now I have it. These babies may get some extra treatment over the next little while. I am thinking of framing it and running grill cloth along the edges to hide the ugly bits. That might be just the ticket. Lord knows I have so many 'test' cabinets that I owe myself a nice set.
Man these are really something. Close your eyes and you are listening to a much larger woofer. I've had that experience a number of time including the CSS EL70 in a planet10 MKIII Frugel horn, but this is almost overwhelming. I am going to have to move them away from the wall as for the first time in my life I am using a Fostex driver and the vocals are recessed. No kidding, this is ridiculous. I have only medium stuffing in and around the driver so I may want to add more depending on what happens when I move them to a new location.
Man these are really something. Close your eyes and you are listening to a much larger woofer. I've had that experience a number of time including the CSS EL70 in a planet10 MKIII Frugel horn, but this is almost overwhelming. I am going to have to move them away from the wall as for the first time in my life I am using a Fostex driver and the vocals are recessed. No kidding, this is ridiculous. I have only medium stuffing in and around the driver so I may want to add more depending on what happens when I move them to a new location.
Cal,
You are the man! I'm glad it all worked out for you Cal, and thanks for having the gumption to try it. I am glad to have been able to make this once elusive speaker, more accessible. Thanks for the kind words.
I guess these are pretty special to make it past test cabinets to getting framed and dolled up with grill cloth? Yes, that is funny to hear that a Fostex has underwhelming vocals drowned by prodigious bass. Rather than moving from walls as these are wall mount speakers, probably dense stuffing In speaker chamber, with more in channels will probably solve it. I was lucky with my Vifa's the balance between bass and mids was good to go - probably because they are smaller with Fs of 120 Hz and my channels are shorter. I wish I could hear yours.... do you have a nice digital recorder with xy mike to record sample of what it sounds like? I may do the same and we can swap listening experiences, albeit, can't be the same as room acoustics and our ears play a big role, I am just curious about the bass.
I know what you are gonna be doing with your free time in the next few days... trying all sorts of different songs to see how they sound, and finishing them off to look good enough to hang in your bedroom. I hope SWMBO will be pleased - as I have said before these babies have potential for high WAF.
Regards,
Xrk971
You are the man! I'm glad it all worked out for you Cal, and thanks for having the gumption to try it. I am glad to have been able to make this once elusive speaker, more accessible. Thanks for the kind words.
I guess these are pretty special to make it past test cabinets to getting framed and dolled up with grill cloth? Yes, that is funny to hear that a Fostex has underwhelming vocals drowned by prodigious bass. Rather than moving from walls as these are wall mount speakers, probably dense stuffing In speaker chamber, with more in channels will probably solve it. I was lucky with my Vifa's the balance between bass and mids was good to go - probably because they are smaller with Fs of 120 Hz and my channels are shorter. I wish I could hear yours.... do you have a nice digital recorder with xy mike to record sample of what it sounds like? I may do the same and we can swap listening experiences, albeit, can't be the same as room acoustics and our ears play a big role, I am just curious about the bass.
I know what you are gonna be doing with your free time in the next few days... trying all sorts of different songs to see how they sound, and finishing them off to look good enough to hang in your bedroom. I hope SWMBO will be pleased - as I have said before these babies have potential for high WAF.
Regards,
Xrk971
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Ahh...the Fibonacci Sequence...hmmm, that does appear in acoustic math. I built some waveguides that used the ratio. My philosophy is to not proceed with a prototype unless I have a mathematical model first. Good luck with your experiments.
As to my idea...for the last month or so I have been thinking of ways to add a "baffle" to the rear of an [open baffle] speaker panel to increase the bass response through time delay of the rear wave field. The deflecting "cornu" spiral with some modifications looks promising to me.
My direction is to try to stay full range or single driver. The spiral rear baffle would save space and still provide time delay. That is opposed to having wide side-wings that take up space. I would also modify the spiral to try and avoid strong standing wave patterns. I was actually encouraged when Cal said it had strong bass.
At art supply stores there is also 1/2" foam core.
Not cheap really but twice as thick which is 4x or 8x as stiff- you engineers will tell me. Might be good for the front and back panels if light weight is a factor.
There's also something called Gatorboard which has phenolic impregnated paper on each side. Very stiff! but quite expensive and a $%^%^$# to cut, so not recommended. Flexy ply for the curves and 1/4" ply front and back panels would be pretty stiff- that spiral has walls pretty close together!!
After getting the perfect design using foamcore first of course..
Not cheap really but twice as thick which is 4x or 8x as stiff- you engineers will tell me. Might be good for the front and back panels if light weight is a factor.
There's also something called Gatorboard which has phenolic impregnated paper on each side. Very stiff! but quite expensive and a $%^%^$# to cut, so not recommended. Flexy ply for the curves and 1/4" ply front and back panels would be pretty stiff- that spiral has walls pretty close together!!
After getting the perfect design using foamcore first of course..
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The completed spiral is actually very stiff and strong for how light it is because it resembles honeycomb panels where all the material is far out at the edges and the core is mostly air. I think it may be the lightest of all speakers that have this much bass. The foam core ones can literally be thrown like a pizza box and fly. The nice thing about being light is it's very easy to hang anywhere, don't need to find studs or use expansion bolts. Just a nail or screw anywhere and no fear of it hurting the kids or pets if it falls.
yeah most doors in houses in the US have thin luan ( a very soft wood) faces with corrugated cardboard stiffeners between them. Wood around the perimeter of course. In fact "doorskins" which are just the wood face are very cheap and might be perfect for the fronts and backs of the speakers.
MJL based calcs would be interesting..
MJL based calcs would be interesting..
Door skins huh? Is that something one can get at Lowes or HD? The door skins if thin and flexible might also be used for the channel walls. I have also seen what looks like Balsa at Michael's that could work. You can steam the wood to soften it before gluing, it would look very old style craftsmanship like and maybe resemble a violin body....
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I have wanted to model this but not sure how to deal with the bifurcation into two different lengths, the rest is straightforward to input into MJK's model. I suppose one can model two separate lengths and solution would be superposition of both? Is MJK still reading these forums?
It is similar to balsa, but not quite as soft, and looks OK stained and with a clear finish. Builders use it to fix damaged doors. But it would require some trickery such as steam or soaking to bend-that could be a nightmare! In fact now that I think about it, its probably 2 ply.. Would probably work for the final flare that is visible from the side. Based on the doors, bent corrugated cardboard could be stiffer than foamcore, and wouldn't require cutting to bend, just roll it up to break it down so it curves, then glue..
I've built a couple of BIB designs and they often don't work well at all if you swap in a different driver than they were designed for- even if the driver is the same diameter. That's why I think calcs for this speaker might really help things along- especially the size of the chamber behind the driver?
I've built a couple of BIB designs and they often don't work well at all if you swap in a different driver than they were designed for- even if the driver is the same diameter. That's why I think calcs for this speaker might really help things along- especially the size of the chamber behind the driver?
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As to the two lengths of the horns I suppose one could try experiments. Run each length and superimpose, and run a length that's the average of the two, with the combined sectional area, and see if there's a difference? I don't know..seems like the second sounds right intuitively.
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The foam board is stiffer than broken down cardboard for curves as only the skin on the concave side is slightly scored. It bends wonderfully and easily as Cal will tell you if you haven't tried it yet. If you seal the scored skin with white glue after it is bent in place it will be even stronger.
WIthout modeling but scaling throat to match Sd seems to work well. I think this horn is so efficient it is forgiving to strict driver matching.
I would just create a single horn with all the bifurcation widths adding up to a total width.
dave
The bifurcations make no difference... you have 4 sections of one length cascaded with 2 of another length. Because it is square and symmetrical bout the centre. You do have a slight discontinuity (The thickness of the spiral material) at the 1st birfircation
You can use a series of concentric circles intersecting with the centre line of a single spiral. The length of the spiral is your x axis, the circumference of the circle is the section (less the width of material crossed ie 2 or 4 material thicknesses).
dave
You can use a series of concentric circles intersecting with the centre line of a single spiral. The length of the spiral is your x axis, the circumference of the circle is the section (less the width of material crossed ie 2 or 4 material thicknesses).
dave