Just had a quick look around and discovered this: M.F.D.S.. - solve the problem by excising the spider! Haven't checked for any comments about this in diyAudio; would be very interesting to have a listen to its characteristics ...
Edit: and also this mob, http://terraspeakers.com/about-us/our-technology/
Edit: and also this mob, http://terraspeakers.com/about-us/our-technology/
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AR did that back in the last century for some of their midrange drivers, Lowther have used the same material for their spiders as they use for their surrounds (foam) for some of their early models, on one of the early B&W woofers the spider was just to keep the dirt out, the "real spider" was hidden under the dust cap, it was a 3 legged spiral cut piece of fiberglass PC board.
You could opt to replace the spider with a wire suspension like Steen Duelund used to do: http://www.steenduelund.dk/scanspeak8554.pdf
Actually Ted Jordan had done a variety of suspension, wired in the Jordan Watts, foam in the JX125 and JX150, and a spiderless Jr6x (I think that's what it is called). Each had their pros and cons. There were some ideas about spider design floating around here, and I was hoping to consolidate some ideas to tweak the spider design at a later date. The real difficult part is trying to find a good BL and Km match over reasonable range. Also working on an amp design that will hopefully more closely integrate with driver characteristics.
Hello, I wonder if the floor reflection might have more effect than the math predicts.
If 1/4 in really matters for driver alignment, then the direct sound and reflect sound mixing together might have a bad effect.
If you or anyone else explored this?
Floor bounce has been measured and heard by many:
The Floor-Bounce Effect – Mic Placement for Equalization Synergetic Audio Concepts
The math predicts correctly, but the path length differences from floor bounce are much greater than 1/4", so show up in the low mid range rather than in the high frequencies.
A 60" tall array with a horn in the path of the middle speakers will "help" provide multiple floor and ceiling bounce issues as well as reflections from the back of the horn.
The dog in the background appears to be trying to hang himself, my reaction would not be that extreme
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I think I'd build a box before i'd waste my time on building something like that open baffle "waveguide" thingee.
This is where I have got to.
There are too many flaws in the components used in making a complete speaker, using only the design software and testing software. Nobody can really apportion with absolute accuracy what what each and every part can do, and there are so many different directions with drivers alone.
We all started with some idea of what we were going to do, but a very few find some insight, that directs them to making an outstanding component or even whole system.
We can all cite examples of this from the past. But at the moment we wait forthis insight and in the meantime keep trying our own ideas. Suck it and see.
Some low-level input
Lynn -
I'm definitely with you on the whole low-level signal issue and the concerns about spider materials etc.
My own activities with the 120Hz tractrix horn -
audio-talk :: View topic - Something stirs in the Undergrowth
..have led me to conclude, so far, that the Fane Studio 8M may not be ideal for this application - it's quite a heavy-duty driver, and it doesn't sound as good, at normal playing level , in this horn , than the B&C 8PE21 that I tried before. I wonder if Martin was really on the right track with these bass or bass/mid horns in using the Lowther PM2A or Vitavox drivers, which are designed for lower-level signals ? As you say - the horn-loading can't help but show-up these problems, given the very low excursions.
I wonder also if Romy's use of the Tannoy 'injection' channel was a way of fixing this problem ?
Makes one think that the compression driver, with its aluminium flexures, is a very attractive technical approach to the low-level signal issue .
Meanwhile, here is my take on how to drive the two horns , avoiding the passive crossover . Apologies to Lynn for the 1st-order slopes, but I'm with Bruce on this : from the limited work I've done with 1st vs. 2nd-order slopes with the AH425 / Onken or AH425 / 120Hz horn .
audio-talk :: View topic - A 2 or 3-channel SE 'Horn-amp'
Lynn -
I'm definitely with you on the whole low-level signal issue and the concerns about spider materials etc.
My own activities with the 120Hz tractrix horn -
audio-talk :: View topic - Something stirs in the Undergrowth
..have led me to conclude, so far, that the Fane Studio 8M may not be ideal for this application - it's quite a heavy-duty driver, and it doesn't sound as good, at normal playing level , in this horn , than the B&C 8PE21 that I tried before. I wonder if Martin was really on the right track with these bass or bass/mid horns in using the Lowther PM2A or Vitavox drivers, which are designed for lower-level signals ? As you say - the horn-loading can't help but show-up these problems, given the very low excursions.
I wonder also if Romy's use of the Tannoy 'injection' channel was a way of fixing this problem ?
Makes one think that the compression driver, with its aluminium flexures, is a very attractive technical approach to the low-level signal issue .
Meanwhile, here is my take on how to drive the two horns , avoiding the passive crossover . Apologies to Lynn for the 1st-order slopes, but I'm with Bruce on this : from the limited work I've done with 1st vs. 2nd-order slopes with the AH425 / Onken or AH425 / 120Hz horn .
audio-talk :: View topic - A 2 or 3-channel SE 'Horn-amp'
Low level detail is a byproduct of "fully horn loaded" - when you achieve 108 db/w/m over say 60 to 12K you have a system that more then likely will reproduce and follow low level transients that hide in lesser systems. For example my full range 85 db/w/m electrostats loose most of it but still manage to sound pleasant, pleasant but not real.
PS- this romy character, why do people listen to somebody (and repaeat the mistakes) that can't figure out round bass horns are a huge waste of time and materials? A rectangular horn can take up much less precious space (especially vertically!) and rectangular horns can be spaced much closer together to create much more humongous sound and coherency with better controlled dispersion.. Round horns frankly are a fad. "Spherical wave fronts" BUNG
PS- this romy character, why do people listen to somebody (and repaeat the mistakes) that can't figure out round bass horns are a huge waste of time and materials? A rectangular horn can take up much less precious space (especially vertically!) and rectangular horns can be spaced much closer together to create much more humongous sound and coherency with better controlled dispersion.. Round horns frankly are a fad. "Spherical wave fronts" BUNG
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If the input signal was measured for level, HD IMD and the output sound was measured similarly for a selection of musical sounds starting from an out put of the onset of audibility to some figure say a typical 85dB listening level then the onset of diaphragm initiation would become visible and could be related to the compliance of the spider and diaphragm surround. The Radian 745Neo was likely never designed with very low level outputs. Surely driver manufacturers do this to assist in the finalised design. Do Radian claim anything for low outputs ?
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Here is a pic of Romy's 250Hz cut off mid bass horn mouths, they are a straight horn and built into the area above the kitchen. His seating position is time aligned between these and the round horn system at the other end of this room. His true bass is still provided by 4 or 5 stacked 10" bass drivers in individual sealed cabinets per channel, no ports.
