For wide baffles these kind of huge roundovers really help! 10-12" drivers. For 8" or smaller you should be fine with 30mm - but when it's doable to increase in the tweeter area ... you could do less (50-60mm) when you prefer a cleaner optic.
Midrange in tubes - be careful! A tube has strong resonances - they are resonators! Think about instruments ... lot's of tubes are used there. So you need proper dampening in the tube and maybe en expo flare at the end to make that work well.
What euphoric midrange driver will yo use?
I will have to use the crossover designed by Jim, if it would indeed be so impactful then maybe indeed I should go with standard roundovers... I have asked Curt by their own contact form, we shall see what he says if he can be contacted at all...
I don't really worry about the mid tubes since they're going to be veeery beefy. They themselves used ones with 8mm wall thickness - I can't get any like that so it's likely I will have to use 10.7mm wall thickness ones instead - that's a lot of solid mass, they shouldn't resonate. And inside them there will be deadening material - either acoustilux or something else. And about the speaker being commercial... it's fully DIY, I don't think they get any serious money from it. It rather seems to be a thing made by them on their top-of-the-line designs where the mids are in open tunnels. Flat face is definitely made because the speakers are supposed to be manufactured not with advanced CNC machines but rather normal tools - table saws, manual routers etc, no way to create complex roundovers on them that way.
Sadly I don't have enough budget to just throw around and try 😉 I would definitely love them to work better with these variable roundovers - the way they look is amazing and I would love such a beautiful design. I am however worried they would sound worse, that's why I sadly can't try. Almost half of the entire speaker budget are going to be these boxes - I can't afford to screw it up there.
These drivers are 2x8" woofers, 5" mid, tweeter, 5" mid again. 30mm for woofers is I think the most I can reliably do, maybe I could go for 35 or 40mm instead, I will have to see. Other than that, I definitely prefer the 30->90mm taper that I modeled, it looks amazing! The only question is if it wouldn't actually hurt the sound instead of improving it...
I asked the designers if the flaring would be recommended, I will have to see 😀 I could make a 18mm radius roundover at the ends of the tunnels to disperse the sound better. Other than that, the walls of these tubes will be extremely thick with good dampening inside.
The design uses a new solution from SB Acoustics - the ceramic SB15CAC30-8, it's a 5" driver with supposedly amazing clarity and detail. I hope for monumental sound paired with these double 8" Dayton RS225 should move some air and create something lifelike. I currently use Monitor Audio RS6, these should be a big step up 😀
Here is the problem with midrange tubes, the lengths required are in the passband of the midrange driver. For example a tube 11 1/4" long will resonate at 1,000Hz. It will resonate at every multiple of that frequency and at 1/4, 1/2, etc. Tubes and enclosures in general can be problematic in the midrange. Adding a flair turns the tube into a back wave horn which has just as many issues and may amplify the rear wave. It's best to model it first. Heavy damping can turn the tube into an aperiodic enclosure, which is what I think you are making. The system designers may have compensated for the resonances somehow with damping and crossover tricks.
Which midrange or HPM xxx model might be helpful.
More then one that used the 100mm (4") cone midranges.
A few different paper versions at least. Also there is the PG (Polymer Graphite) cone version in fx HPM 900, with a more damped cone, smootish response generally, and higher breakup frequency.
There was HPM 30 -> HPM 1100.
Those have the PG -Polymer Graphite cones.
Sure the material have some good characteristics,.
Just be careful with the drivers, repair is not possible and the cones are fairly fragile. The cone material was put out of production long ago due to cost mainly.
You will find it in other speakers/drivers then only the HPM range though. Pioneer/Pioneer exclusive/TAD have used it in some models.
The rear output will be highly directional at all frequencies within the passband of resonance....in other words.......the listener will never hear it. What the listener WON'T hear is the rear wave and enclosure resonances coming back through the cone toward the listener.......which is the whole intent and purpose of the design.
Curt is an awesome guy and long time DIY community supporter...he will absolutely respond to your email inquiry
Disregard the tube resonance nonsense.....some of these fellas will beat a dead horse beyond the maggots. The resonances if any will rear firing, highly directional and so low in amplitude to make them completely inconsequential.
Your baffle design from a visual perspective looks great! I don't think anyone can fully predict what the tonal changes will be as the directivity of the wave fronts is going to be different....the audibility of those changes will be heavily dependent on placement and the acoustic space these are in.
Hi, there must be no resonance in the tube, iow it must be dampened, otherwise it would not be any different from resonance inside enclosure, although at different frequency since other end is open so octave lower and definitely in pass band. So feels a marketing/differentation trick. Perhaps it makes nice high pass slope or something, reduces power below MTM action or something, which makes the tubes worthwhile. Resonate it will so it's likely damped, similarly would the bormal closed enclosure dampen, so this backwave reflection thing is not the strong case for it. At least it looks like so, ai haven't even read about the design principles 🙂
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It's a sorta of quarter wave load where the damping recessed near the output (one to few inchses) of the the tube and in a middle of the tube reduce and damps the wave without being obstructive like a variovent. There is certainly a trade off to find with the length of the tube of better a cone, the internal damping towards the damping, so it is loading like the quarter wave principle ? Don't know if aperiodic, certainly faster so not the same Q ?
You certainly can measure it at the low end flatened impedance and own taste at listening
You certainly can measure it at the low end flatened impedance and own taste at listening
One of my top 3 is old 5,25 inch Audax HM130Z0.
From ca 200 hz to ca 3K in a 20 liter rectangular box
From ca 200 hz to ca 3K in a 20 liter rectangular box
too bad the HM100Z0 is not produced anymore !
If I had enough monney to loose, I frankenstein the HM 130Z0 : take the voice coil and aerogel cone, put it in a better motor/chassis : Peereless NE, Illuminator/Revelator, BMS, Satori. And try to select high Qms spider and foam inverted surround ! 😎
I wonder if so with less efficienty the bad impedance and not ideal spl curve could be enhanced....
There is something with those aerogel cones in the midrange...
If I had enough monney to loose, I frankenstein the HM 130Z0 : take the voice coil and aerogel cone, put it in a better motor/chassis : Peereless NE, Illuminator/Revelator, BMS, Satori. And try to select high Qms spider and foam inverted surround ! 😎
I wonder if so with less efficienty the bad impedance and not ideal spl curve could be enhanced....
There is something with those aerogel cones in the midrange...
I got lucky with the woofers as that old retro store refoamed both HPM 900 woofers with no damage. The cone material is brittle both mid and tweet use a folded paper surround, still like new, and have the metal mesh covers.
I call for a class action against Kurt Muller and Vifa/Scan Speak for having given up foam suround genuine gasket for the Vifa P13 refurbishing ! 😡🥷
Baby Kurt if you read me : please provide the parts for maintenance in a global warming world : foam and rubber are ligth, plain drivers are not to ship and produce !
And as the Revelator are rotten and one of the eyes of your speakers can not blink anymore I call for a new name for the Revelator : Albator or perhaps Odin driver !
Baby Kurt if you read me : please provide the parts for maintenance in a global warming world : foam and rubber are ligth, plain drivers are not to ship and produce !
And as the Revelator are rotten and one of the eyes of your speakers can not blink anymore I call for a new name for the Revelator : Albator or perhaps Odin driver !
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Imma wrap these tubes in bitumen mats inside and out 😉
Curt said I should go for it so I shall definitely try!
You most certainly will hear it. Whether it's a closed or open pipe there is resonance and there are harmonics. In an open ended tube the sound doesn't squirt out of the back like a fire hose, it radiates out of both ends just like it does for a flute. In the first harmonic, the open tube contains exactly half of a standing wave. A closed tube resonates at the same fundamental frequency as an open tube twice its length, with a wavelength equal to four times its length. The higher frequencies can be damped, the lower frequencies not so much, doesn't matter if the pipe is closed or open.