I've been trying to decide what to do with my next project in terms of a Grill (or Grille for those across the pond). Edge diffraction effects appear to be extensively discussed:
http://www.diyaudio.com/forums/multi-way/222037-whats-sharp-edges-speaker-boxes-these-days-4.html
http://www.diyaudio.com/forums/multi-way/232834-speaker-cabinets-edge-diffraction.html
etc.
But what about the Grill? Seems like most conventional Grills would have a much larger impact than the baffle edge? Any simulations or studies on this that folks are aware of?
One of the few threads on this subject has few posts:
http://www.diyaudio.com/forums/multi-way/180015-flush-mount-grilles.html
Speaker Dave's Flush mount Snell ABX looks awesome but really opens a can of worms for DIY'rs with respect to mounting the drivers on the baffle for enough Xmax on the woofer and room for the tweeters dome (if that's your tweeter choice).
I have played around with "The Edge", BDS (Baffle Diffraction Simulator) and the bevel settings in Boxsim. I built my last project with a hefty roundover : (photo below)
but for a 2 way I want to build if I want a Grill do I just give up on the Baffle edge rounding??
http://www.diyaudio.com/forums/multi-way/222037-whats-sharp-edges-speaker-boxes-these-days-4.html
http://www.diyaudio.com/forums/multi-way/232834-speaker-cabinets-edge-diffraction.html
etc.
But what about the Grill? Seems like most conventional Grills would have a much larger impact than the baffle edge? Any simulations or studies on this that folks are aware of?
One of the few threads on this subject has few posts:
http://www.diyaudio.com/forums/multi-way/180015-flush-mount-grilles.html
Speaker Dave's Flush mount Snell ABX looks awesome but really opens a can of worms for DIY'rs with respect to mounting the drivers on the baffle for enough Xmax on the woofer and room for the tweeters dome (if that's your tweeter choice).
I have played around with "The Edge", BDS (Baffle Diffraction Simulator) and the bevel settings in Boxsim. I built my last project with a hefty roundover : (photo below)
but for a 2 way I want to build if I want a Grill do I just give up on the Baffle edge rounding??
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The first test is probably to get someone to remove the grille while you are listening to music with eyes closed. If you hear a significant difference then obviously you don't want to use a grille.
If you have youngsters and small kids around you might need to use a grille even if it didn't sound right !
I've always found ( at least 'felt' !) that the sound is better without a grille. All you can do by researching it is which grille is least intrusive ! If you have plenty of spare time it's a good idea to check it out. If not, just check out if 'your' grille causes a problem and decided to use it or not.
I do remember reading some articles on this a very long time ago. The conclusion was that it did alter the sound. Will be hard to find those but a Google might bring up something.
Very nice looking OB. How does it sound ? How is the low end without any bass assistance ? What are those drivers ?
If you want protection I'd use a slip on cover like a sock made of very thin material. You can just slide it off when listening to music seriously ( as apart from listing to music while doing other work around the house !).
Cheers.
If you have youngsters and small kids around you might need to use a grille even if it didn't sound right !
I've always found ( at least 'felt' !) that the sound is better without a grille. All you can do by researching it is which grille is least intrusive ! If you have plenty of spare time it's a good idea to check it out. If not, just check out if 'your' grille causes a problem and decided to use it or not.
I do remember reading some articles on this a very long time ago. The conclusion was that it did alter the sound. Will be hard to find those but a Google might bring up something.
Very nice looking OB. How does it sound ? How is the low end without any bass assistance ? What are those drivers ?
If you want protection I'd use a slip on cover like a sock made of very thin material. You can just slide it off when listening to music seriously ( as apart from listing to music while doing other work around the house !).
Cheers.
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If you don't mind the look of it, a few strategically-placed nubs holding wrapped grill cloth off the driver wouldn't get in the way much, or even a frame of stiff round wire.
Depends on the kind of grille. If you use cloth on a wooden frame (is this still called a grille in English? Not sure about it) it will surely affect the frequency response, and renders any roundings irrelevant. Of course you can minimize the effect.
A steel sheet grille won't do much.
A steel sheet grille won't do much.
Here are some measurements:
Grill frame diffraction effects on frequency response
and the suggestion that felt around the tweeter reduces the effect
Grill frame diffraction effects on frequency response
and the suggestion that felt around the tweeter reduces the effect
The grill material is not an issue, but the frame can be a big issue. The frame can cause serious problems in the critical 1kHz - 5 kHz range. Best to not use a grille unless you can do it so that there is no increase in the baffles smoothness as a result.
Absolutely what I was concerned about - I should have articulated my question better. Your response confirms my fears. I guess this was just a sanity check to justify not using a grill (or just using it as a dust cover when not using the speakers). 🙂
Thanks
Thanks for the link to the measured responses. Helps me gauge how much to weigh these concerns compared to other tradeoffs. Looks to me like the felt did not really solve the problem - only move it up in frequency, but hard to be conclusive with that set of data. - would have been better to see the "felt on frame" comparison to an "unfelted" yet grilled speaker of the same design.
Thanks!
Ok - try not to laugh so hard - but when I explain the history of this speaker project you'll understand why the listening test would not be very fruitful for me...
Below is a picture of 2/3rds of those speakers in their form before my son picked up my dusty 1980 copy of Weems' "How to Design, Build and Test Complete Speaker Systems" and said 'dad - build me a set of speakers like the ones you built in college'
Note to horrid Piezo tweeter, driver placement, polar electrolytic caps, 22AWG inductor, baffle edge...😱 With modern simulation tools I saw that the supposed smooth Butterworth crossover had a >5 dB dip due to my not accounting for the woofer Le. And forget about any attention to phase. Was anything right? Well - I had replaced the woofers in 2007 with Dayton RS225S models due to the rotted foam on the originals. And I did recall that the Mid was originally the most expensive part of the system at $60 (1980 $s that is) as still sounded good to my ears. (It says made in Belgium on the back, is Ferrofluidically cooled, is sealed, has an fs of 380Hz based on notes I scribbled in Weems's book and has no name)
So - after building my son a budget 2 way set (that's another story) I bought some SEAS 19TFF1 tweeters, some Birch plywood, some nice crossover components to make a 2nd O LR, and converted the old beast to the picture above. You might consider it a ba$tardized poor man's combo of the Sunflower redux:
https://sites.google.com/site/undefinition/diy-sunflowers
(I took the sloped, ported bass box and flipped it 180 degrees to provide voice coil alignment)
combined with a baffle edge treatment borrowed from this masterpiece:
http://www.diyaudio.com/forums/multi-way/226914-my-refspeaker.html
that "taught" me how to bend plywood.
(So - sorry - it is not an OB design - the curves are to help the tweet and mid diffraction and because I didn't want to use birch on the other sides - built the things in 2 weekends)
Net - in the middle of the project I tested 1 of the new crossovers in the old box. Only then in a side by side listening test could I detect the >5db dip - which btw I confirmed with a home made panasonic microphone and Tombstone" software outside in my back yard. Until then I was blissfully happy with my old speakers for 3+ decades.
So - clearly I am in no position to judge any subtlety in this speaker system via the test you suggest above - though I do love the way this new version sounds, most of my fuss over details like the edge rounding are because I know it can be measured and thus figure I might as well try to address it even if I am not sure I will be able to hear it.
(I did say don't laugh too hard right? 😱)
So....Not so fat, arguably dumb and yet blissfully happy.....
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It seems to me the best way to eliminate grill frame effects is to eliminate the frame. I'd look for perforated metal that is strong enough to hold up while supported only on a few points:
and mount it on posts. Post-shaped magnets that would seem to offer some creative possibilities are available at several science hobby sites. Optionally cover with grill cloth of your choice.
The trick is of course finishing the edges in a visually acceptable way without heading too far along the road that leads back to frame-land. I'm thinking some time spent with snips, sandpaper and flat black paint (no cloth, thanks) would work for me.
Or go retro-modern and use a sheet of reticulated foam instead of cloth.
and mount it on posts. Post-shaped magnets that would seem to offer some creative possibilities are available at several science hobby sites. Optionally cover with grill cloth of your choice.
The trick is of course finishing the edges in a visually acceptable way without heading too far along the road that leads back to frame-land. I'm thinking some time spent with snips, sandpaper and flat black paint (no cloth, thanks) would work for me.
Or go retro-modern and use a sheet of reticulated foam instead of cloth.
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That's a cool mesh - what is the length scale of the openings and where did you get it? I guess there might be 2 fundamental reasons why one would want a grill (or 3 if the spouse is involved): Dust, kids poking things, aesthetics. My kids are grown up so until they have kids of their own my only consideration is #1
Thanks
david, good idea.
Nvr, sorry to say that's just a random picture Google found for me. I believe that type is called hexagonal perforated metal, and I picked it because that arrangement allows it to be mostly air.
Nvr, sorry to say that's just a random picture Google found for me. I believe that type is called hexagonal perforated metal, and I picked it because that arrangement allows it to be mostly air.
By arching the mesh, you can fold the side edges into slots in the cabinet, avoiding some of the cosmetic, safety and acoustic compromises. I have never seen grille frames simulated, but this might be able to do the job AcouSTO - Acoustics Simulation TOol - Homepage
Even with no kids around, vacuum cleaner handles are a hazard to speakers
Even with no kids around, vacuum cleaner handles are a hazard to speakers
Good idea - Arching mesh might look good and not impact the sound too much for those that want the physical protection. Thanks for the software link - reading the description it does indeed sound like it could do the job but looks like it takes someone familiar with Linux to run it I think - so that kinda rules me out.🙁
Maybe some of the more software inclined folks on the forum will find it useful! Thanks!
Yes. Grill is a noun to mean a cooking surface, or as a verb; to grill your food.
Grille is the correct spelling for the thingy what protects your speakers. 🙂
Damn - I always assumed that was Queen's English thing - I never could spell, Thanks for setting me straight
The lines are blurred from country to country I'm sure. I decided to look it up and found one site where grill is acceptable as a speaker covering so who knows...
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