Pondering about baffle shapes, also about the manufacturability. Here's the "25 degree facet for all" approach I like:
Revelator 15M baffle simulation with traced manufacturer FR for the SMOOTH top speaker:
Comparison with Zwicker's curve:
Revelator 15M baffle simulation with traced manufacturer FR for the SMOOTH top speaker:
Comparison with Zwicker's curve:
Hi Peter,
For a smoother BS, I looked for a way to do the design of the first picture with 1/4 round angle, but as deep as your picture, but alas never found an handy way to do this.
Because of the baffle cabinet, what do you think of something between 2 & 3 pictures but with a larger base in order to match at the base, the width of the baffle cabinet like the What Puppy ?
I don't know if that difractions are harmless or not if the monitor is staying less widther than the bass cabinet top ?
Doesn't seem to makea J. Gherrard asleep in his last designs (Suesskind Ausio).
For a smoother BS, I looked for a way to do the design of the first picture with 1/4 round angle, but as deep as your picture, but alas never found an handy way to do this.
Because of the baffle cabinet, what do you think of something between 2 & 3 pictures but with a larger base in order to match at the base, the width of the baffle cabinet like the What Puppy ?
I don't know if that difractions are harmless or not if the monitor is staying less widther than the bass cabinet top ?
Doesn't seem to makea J. Gherrard asleep in his last designs (Suesskind Ausio).
Hi, I have several design constrains to consider also due to my manufacturing capabilities.
I'm more the system designer and integrator guy, not so the hobby carpenter and have no workshop room at home.
I will order all birch plywood panels by drawing readily cut, mitered and with 2.5D CNC milled cutouts, and glue the enclosures together literally on the kitchen table with adhesive tape and tension belt method. Some features like chamfers I will apply with a simple hand router in the garden as well as final sanding and waxing after assembly. I might use the circle saw of a neighbor for an evening to make the flat facets on the front baffles, and generally I'm limited to cuboid enclosure shape. Further, I want to keep the top speakers comparably tiny to get them properly stored when not used. And during the design process I've limited the baffle thickness to 21mm that cutouts for the small drivers get not so deep and the drivers can "breath" well into the enclosure with proper chamfering then.
For the facets, I've chosen the 25° angle due to the investigations of Hobby Hifi magazine, that many years ago tested several baffle facet/chamfer angles between 10°- 60° degree or so, and the result was that 25°-30° degree facet angle gives best compromised result. As within this angle range there is not much difference, take 25° to keep the baffle getting not too thick. Since then, Hobby Hifi puts 25° facets everywhere over their speakers because it seems to work well for this overseeable measurement: https://www.lautsprechershop.de/hifi/journal_hobby_hifi.htm
I do not fear so much some reflections caused by the upper edge of the woofer enclosure, but fear more some compromises in directivity behaviour when the baffle width is too much different between both stacked enclosures. I want to keep the baffle width for the SMOOTH top speaker so that baffle diffraction linearizes driver respose somewhat, that by chance matches also Zwicker's curve, and to keep the target passband of the mid within halfspace radiation above the baffle step in general. I miss the goal by ~100Hz; Assumed xover is ~300Hz LR2, but midrange leaves halfspace radiation below 400Hz. But loss in baffle gain is <1,5dB at 300Hz, so this compromise is okay for me. Maybe I give the baffle another 5mm widht:
For the SMOOTH and CLEAR design I'm pretty sure this will be the design I will implement.
The CLEAR speaker and it's cardioid vents behaves different and shall be filtered ~250Hz LR4 as it can maitain directivity down so low.
For the DRY approach I might take intentionally a bit sleeker baffle, must do some more simulations to decide...
I'm more the system designer and integrator guy, not so the hobby carpenter and have no workshop room at home.
I will order all birch plywood panels by drawing readily cut, mitered and with 2.5D CNC milled cutouts, and glue the enclosures together literally on the kitchen table with adhesive tape and tension belt method. Some features like chamfers I will apply with a simple hand router in the garden as well as final sanding and waxing after assembly. I might use the circle saw of a neighbor for an evening to make the flat facets on the front baffles, and generally I'm limited to cuboid enclosure shape. Further, I want to keep the top speakers comparably tiny to get them properly stored when not used. And during the design process I've limited the baffle thickness to 21mm that cutouts for the small drivers get not so deep and the drivers can "breath" well into the enclosure with proper chamfering then.
For the facets, I've chosen the 25° angle due to the investigations of Hobby Hifi magazine, that many years ago tested several baffle facet/chamfer angles between 10°- 60° degree or so, and the result was that 25°-30° degree facet angle gives best compromised result. As within this angle range there is not much difference, take 25° to keep the baffle getting not too thick. Since then, Hobby Hifi puts 25° facets everywhere over their speakers because it seems to work well for this overseeable measurement: https://www.lautsprechershop.de/hifi/journal_hobby_hifi.htm
I do not fear so much some reflections caused by the upper edge of the woofer enclosure, but fear more some compromises in directivity behaviour when the baffle width is too much different between both stacked enclosures. I want to keep the baffle width for the SMOOTH top speaker so that baffle diffraction linearizes driver respose somewhat, that by chance matches also Zwicker's curve, and to keep the target passband of the mid within halfspace radiation above the baffle step in general. I miss the goal by ~100Hz; Assumed xover is ~300Hz LR2, but midrange leaves halfspace radiation below 400Hz. But loss in baffle gain is <1,5dB at 300Hz, so this compromise is okay for me. Maybe I give the baffle another 5mm widht:
For the SMOOTH and CLEAR design I'm pretty sure this will be the design I will implement.
The CLEAR speaker and it's cardioid vents behaves different and shall be filtered ~250Hz LR4 as it can maitain directivity down so low.
For the DRY approach I might take intentionally a bit sleeker baffle, must do some more simulations to decide...
How deep is the recess at thetop of the cabinet, please ? (it gives the deepness of the baffle to saw the recess)
All baffle chamfers and facets = 25°
Front panels are 21mm thick.
But the answer is 42 😉:
SMOOTH baffle sim looks okay to me now also for the tweeter (blue line):
For the DRY baffle i did a little tradeoff, have chosen the "long" version then:
Front panels are 21mm thick.
But the answer is 42 😉:
SMOOTH baffle sim looks okay to me now also for the tweeter (blue line):
For the DRY baffle i did a little tradeoff, have chosen the "long" version then:
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Student version of a 15 year old commercial SW on a Windows XP virtual machine to keep it running for hobby purpose...
Okay I think this is enough effort spend for now with the baffles:
From left to right the width decreases by 2 cm per baffle and height increases by 3 cm. Baffle overall surface footprint is closest same for all three.
Mids are all on same height. Nice round numbers for all key values. All chamfers and facets 25 degrees. Common manufacturing approach. And: 42...
The CLEAR top speaker has increased size now by 1 cm in each width and height direction, i spend this deviation from the ASR Directiva r2 for better appearance that the baffle looks not so tight and crowded and as contribution to the platform concept:
Will work out the back enclosures for the DRY and SMOOTH top speakers as next step. And an additional baffle for the ULTRACLEAR Bliesma dome variant in advance.
Best regards
Peter
From left to right the width decreases by 2 cm per baffle and height increases by 3 cm. Baffle overall surface footprint is closest same for all three.
Mids are all on same height. Nice round numbers for all key values. All chamfers and facets 25 degrees. Common manufacturing approach. And: 42...
The CLEAR top speaker has increased size now by 1 cm in each width and height direction, i spend this deviation from the ASR Directiva r2 for better appearance that the baffle looks not so tight and crowded and as contribution to the platform concept:
Will work out the back enclosures for the DRY and SMOOTH top speakers as next step. And an additional baffle for the ULTRACLEAR Bliesma dome variant in advance.
Best regards
Peter
Looks good.
How much is the dB efficienty loss with such cardioid cabinet,, please ?
Fb is the same as a sealed according the size of the internal volume, but will have a 18 dB slope in the lows and a cardioid radiation figure, rigth ?
looking forward to see how you will tune that cardioid felt brakes behinds the lateral slots.
Good project ! 🙂
How much is the dB efficienty loss with such cardioid cabinet,, please ?
Fb is the same as a sealed according the size of the internal volume, but will have a 18 dB slope in the lows and a cardioid radiation figure, rigth ?
looking forward to see how you will tune that cardioid felt brakes behinds the lateral slots.
Good project ! 🙂
Have to search in the bunch of threads at ASR for a reference, but the outcome was that with proper damping (yep have to figure this out then) there is no SPL loss on axis, even a little gain of a dB or so with such a design. There is loss then to the side outward angles that appears as directivity increase hopefully as desired. Sims for the ASR enclosure showed CD nearly down to 200Hz with quite linear SPL but the little SB must give some duty when used so low. Plan to xover at ~250Hz LR4. SMOOTH around 300 Hz LR2, DRY about 350Hz LR4. Measurements will show.
My CLEAR enclosue design is slighty larger than the Directiva r2 as main deviation, especially on the top behind the tweeter. Thinking about reducing it internally somehow...
My CLEAR enclosue design is slighty larger than the Directiva r2 as main deviation, especially on the top behind the tweeter. Thinking about reducing it internally somehow...
Maybe have a look at mabat's simulation of resistive midrange here (+ following posts):
https://www.diyaudio.com/community/...-design-the-easy-way-ath4.338806/post-7246438
https://www.diyaudio.com/community/...-design-the-easy-way-ath4.338806/post-7246438
With chamfer on the lower edge of the top speaker baffles:
Or without?
Without looks cleaner, or?
Or without?
Without looks cleaner, or?
Yes, that's why I came to the idea with the chamfer.
Looks like this, compare with before. Hard to decide:
Looks like this, compare with before. Hard to decide:
Sorry could not resist ...
(just a slight cut-away that might also reduce early reflections)
Edit: could also just be a darker stain, for visual appearence.
(just a slight cut-away that might also reduce early reflections)
Edit: could also just be a darker stain, for visual appearence.
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Hi, yes that would be nice but not within my manufacturing capabilities...
New baffle for ULTRACLEAR top speaker:
New baffle for ULTRACLEAR top speaker: