So, I start to clad the body of the speaker with 1/2" maple veneer particleboard. This will be the outside layer of the CLD system. It's also for appearance, ultimately it will be stained and finished with waterbased polyurethane.
It's a little tricky: first I have to leave space between layers for the silicone caulking that will be the lossy layer/adhesive.
Second, the side panels have to be carefully scribed to the curved baffle.
Third, is that I want there to be no end grain of the particleboard showing, therefore all joints are mitred.
These three factors make for some very precise cutting. I put a freshly sharpened blade in the tablesaw and have at it.
It takes exactly 1 full sheet to clad these speakers. Careful cutting and re-cutting, I get the first side fitted. Lots of silicone, and moderate clamp pressure to hold it in place.
I need to wait for the silicone to set before fitting the next piece. That's what this projects all about - waiting.
It's a little tricky: first I have to leave space between layers for the silicone caulking that will be the lossy layer/adhesive.
Second, the side panels have to be carefully scribed to the curved baffle.
Third, is that I want there to be no end grain of the particleboard showing, therefore all joints are mitred.
These three factors make for some very precise cutting. I put a freshly sharpened blade in the tablesaw and have at it.
It takes exactly 1 full sheet to clad these speakers. Careful cutting and re-cutting, I get the first side fitted. Lots of silicone, and moderate clamp pressure to hold it in place.
I need to wait for the silicone to set before fitting the next piece. That's what this projects all about - waiting.
Attachments
Cloth Ears said:
Thanks Jon,
The second layer of MDF on the baffle is just glued using yellow carpenter's glue and every clamp that I own. Spreading the glue liberally to get 100% coverage. I left them clamped for several days, to be sure they were completely set.
The styrofoam that you sprayed the bed liner on (I had the same stuff in mind), was it the white one thats made of little balls? We call it polybead here. Or is it the blue polystyrene by Dow or the one that I'll use is by Owens Corning (it's pink)?
I will test beforehand though and wait a day or two (it's all about waiting).
MJL21193 said:
It was a while back, and I'm sort of remembering Dulux (local?) or Duplicolor (US). Trouble is, the cans were yellow (and neither of these brands currently is) and I can't seem to find a picture of the right one on the 'net. Whatever it was, it was a straight 'rubber' (exact chemical composition unknown) which dried flat (and matt) when sprayed on a wood surface. And, it fooled the hell out of me when I first sprayed it on the styrofoam - it held its' shape for a couple of hours and I didnt't look at it again until the next day (wherein it had eaten nearly half the 4 inches of foam). Mind you, the surface of the 'rubber' hadn't broken, so I thought my eyes were being fooled at first.
If you're using silicone to glue on the styrofoam, then maybe you could use a layer of that to protect your wedges from it.
I'm planning on using wedges of the foam used to pack computer parts in (it's a beautiful pink colour) for the same purpose in a (sadly delayed) project. No covering, and possibly no glueing required as it'll probably sit nicely in the section of panel (I'm planning on cutting them so that they are 1 centimetre too wide).
Cloth Ears said:
Friction fit on the foam. What's the project?
I've been on the fence about using this method.
Here, I will have a new pair of speakers that are actively driven, use of the silicone CLD method and the sound absorbing wedges. I will not have any basis for comparison. If it sounds great, is it due to one of the about or a combination of all three?
Likewise, if it sounds bad, what is the cause/how do I fix it?
In the end, I will go with the sound absorbing wedges because it seems to be the best solution.
More progress on the build. On the first speaker, everything is going together good. The silicone only needs about an hour until it set enough to remove the clamps.
The other side is cut and fitted. The top is next. Both are glued in place and fit very well.
Attachments
MJL21193 said:
A 2-way TL/labyrinth from some freebies that's been on hold for some time. Philips domes and Paradigm mid basses from a friend, a pair of 'kids benches' (made from a single piece of curved plywood), some scrap 12mm plywood, wire from where-ever, foam from work and either a spare CX2310 I've got lying around, or some caps and coils from a previous project that went active.
It only needs the internals trimmed to fit properly, the foam cut up and for me to decide whether I should mount the drivers properly (the aesthetic in me says yes).
architecturally different....
http://pub48.bravenet.com/photocenter/album.php?usernum=4095425731&album=48032
http://pub48.bravenet.com/photocenter/album.php?usernum=4095425731&album=48032
Different....
In John's first poast on 8-11, he said:
"I have built a few speakers, and I am not a fan of the rectangular box, plain and simple types. I prefer to make it architecturally interesting, it should look stunning and sound sublime."
While John is not interested in a line array perhaps, my LA's are very different and architecturally so, and they sound unbelievably spectacular.
Got it?
Zarathu
In John's first poast on 8-11, he said:
"I have built a few speakers, and I am not a fan of the rectangular box, plain and simple types. I prefer to make it architecturally interesting, it should look stunning and sound sublime."
While John is not interested in a line array perhaps, my LA's are very different and architecturally so, and they sound unbelievably spectacular.
Got it?
Zarathu
Hi Zarathu,
I have examined your line arrays in other threads and will admit, I have been tempted to go that route. There is something very attractive aesthetically about a vertical array of many drivers. I initially planned for my subwoofer to be a vertical stack of 4 or 5 - 12" drivers, but changed my mind and went with 2 - 18" woofers.
I must confess that I haven't heard a good line array in action, so my experience with the sound quality is limited.
The future holds the potential for many projects, and an active line array might be one of them.
I have examined your line arrays in other threads and will admit, I have been tempted to go that route. There is something very attractive aesthetically about a vertical array of many drivers. I initially planned for my subwoofer to be a vertical stack of 4 or 5 - 12" drivers, but changed my mind and went with 2 - 18" woofers.
I must confess that I haven't heard a good line array in action, so my experience with the sound quality is limited.
The future holds the potential for many projects, and an active line array might be one of them.
Andy Graddon said:
Thanks Andy. I know that I'm doing OK when I get compliments from true leaders in the field, such as yourself. Your attention here is much appreciated.
My finishing is the cheap (low cost paint) and lazy (I have to wait several weeks) way to get a respectable finish. It pales in comparison to some others efforts, such as Ant's (ShinObiwan). His just gets better and better.
More progress. Just more, boring panels added. This time the back panel, which I recessed for an aluminum plate - the mounting for the banana jacks.
I've decided to go with banana jacks as opposed to binding post for three reasons: 1. lower profile. 2. I only use banana plugs, not raw (or tinned) wire. 3. They are cheaper, I need 12 of these. Performance of these with matching plugs is excellent, no need for anything better. I use a small amount of dielectric grease on the plugs to prevent oxidization.
The picture shows the rear of the speaker, all done (but concealing an ugly secret. A secret I'll reveal in the next post).
Corners came together very tight, with no gap. It looks as though it has been veneered.
Overall I'm very satisfied with the results so far.
Attachments
John,
My personal opinion is that most line arrays don't pay attention to the details. They are built as if the builder is building a point source speaker.
1. I don't believe in planars or ribbons. Very few of them are sufficiently distortion free, and most are excessively hot. Silk domes are a mature technology and when used in groups give a very high quality almost distortionless sound.
2. Mid ranges need to be between three and four inches so that they can respond intensely and quickly in the 165 - 2400 range. Crossing in the middle of that range produces artifacts that make the speaker just not as transparent.
3. Mid ranges in the 3-4 inch range need to have x-maxes of at least 3 mm, so that sudden crescendos don't send them into distortion.
4. The mid range coloration is a very significant impact in speakers. This gangs in an array if the mid ranges don't have their own totally isolated enclosure.
5. The use of stuffing in enclosures is only useful if the length of the stuffing is long so that the back sound has to travel through it. Narrow back speakers do not use the stuffing at all effectively.
6. Some sound inevitably makes it back through the front of the speaker. Using a closed cylinder makes sure that the only returning sound is actually even ordered harmonics, which in small doses increase clarity.
7. No speaker, and especially line arrays, should be using the power robbing, un-damping, distortion producing passive crossover.
8. Speakers need enormous headroom so that they have the resources to handle transients effectively.
9. Line arrays should function as three ways, so that the woofer element is not a sub woofer, but an actual woofer component in each channel.
10. There is a minimum cost cut-off for the speakers and amplification, which runs around $1500 for the set.
Since almost all line arrays made, commercial and DIY, don't follow these essential principles, these line arrays don't produce the quality of sound necessary to show the animals real quality.
These are my opinions. Since 99% of line arrays ignore most of these points or disagree with their importance, I would expect that more than 90% of people would strongly disagree with the need to do this. But then none of these people have heard my design. Using my design allows one to use less expensive individual speakers and still produce a world class design. Using the best money-no-object-choices raises the bar almost impossibly.
Zarathu
My personal opinion is that most line arrays don't pay attention to the details. They are built as if the builder is building a point source speaker.
1. I don't believe in planars or ribbons. Very few of them are sufficiently distortion free, and most are excessively hot. Silk domes are a mature technology and when used in groups give a very high quality almost distortionless sound.
2. Mid ranges need to be between three and four inches so that they can respond intensely and quickly in the 165 - 2400 range. Crossing in the middle of that range produces artifacts that make the speaker just not as transparent.
3. Mid ranges in the 3-4 inch range need to have x-maxes of at least 3 mm, so that sudden crescendos don't send them into distortion.
4. The mid range coloration is a very significant impact in speakers. This gangs in an array if the mid ranges don't have their own totally isolated enclosure.
5. The use of stuffing in enclosures is only useful if the length of the stuffing is long so that the back sound has to travel through it. Narrow back speakers do not use the stuffing at all effectively.
6. Some sound inevitably makes it back through the front of the speaker. Using a closed cylinder makes sure that the only returning sound is actually even ordered harmonics, which in small doses increase clarity.
7. No speaker, and especially line arrays, should be using the power robbing, un-damping, distortion producing passive crossover.
8. Speakers need enormous headroom so that they have the resources to handle transients effectively.
9. Line arrays should function as three ways, so that the woofer element is not a sub woofer, but an actual woofer component in each channel.
10. There is a minimum cost cut-off for the speakers and amplification, which runs around $1500 for the set.
Since almost all line arrays made, commercial and DIY, don't follow these essential principles, these line arrays don't produce the quality of sound necessary to show the animals real quality.
These are my opinions. Since 99% of line arrays ignore most of these points or disagree with their importance, I would expect that more than 90% of people would strongly disagree with the need to do this. But then none of these people have heard my design. Using my design allows one to use less expensive individual speakers and still produce a world class design. Using the best money-no-object-choices raises the bar almost impossibly.
Zarathu
Zarathu said:
I like textile domes too, but nothing wrong with a good metal dome.
Why not cross higher and avoid the excursion problem? Say 300 to 350Hz? The woofer would have to be capable at that frequency, but that's not a problem for most woofers.
Well, stuffing in any box has it's uses: reduction of standing waves and panel damping. Thickness and density make a difference.
No argument from me on these points.
How do you compensate for the high efficiency of the line array with a single woofer? Amplifier power?
MJL21193 said:
Yesm....... for instance, my "Gumby" arrays drive easily to very loud levels with 35w tubes. The bass drivers are driven by 175wrms a side PA amp, and this is actually what limits the sound level of the speaker. I will not go above where the PA amp limiter light just start to just flicker.
Mind you, at that volume, it is VERY, VERY loud !!, but the because of the array efficiency, it doesn't have an issue.
Gumby is somewhat different from Zar's array, being that it is an open back array, and I could only really afford a single tweeter, and I do use a cross-over for the top x-o point. (differences of opinion are allowed ;-)
My mid drivers are not the cheap stuff he puts up with though, chuckle ;-)
in case you haven't seen "Gumby"
http://members.optusnet.com.au/~gradds55/ARGOS/Gumby.htm
planet10 said:
Thanks Dave. I know your feelings about the MDF used and this type of speaker is not your cup of tea, but what are your thoughts on the overall construction and driver selection/allignment?
Box for woofer is 33 litres, tuning freq. 59hz, F3 is 63, Qtc is .628.
ShinOBIWAN said:
Thanks again Ant.
Looks like I'll get the chance to use the waterbased urethane paint soon. I'm counting on good results.
Andy Graddon said:
Of course I've seen Gumby. Your site is in my IE favorites. I've used your series crossover calc more than a few times.
It would be nice to build a woofer array that comes close or equals the efficiency of the mid/tweet array, but that would be costly. I have a few ideas on this that I'd like to explore.
The hexagonal woofer enclosure on your Gumby brings forth a memory: One of my friends way back in my teenage years asked me to help him build his speakers. I had an idea to have the enclosure octagonal with the tweeter mounted in the centre of the woofer. At first he was all for it but changed his mind.
I didn't have anything to do with the plain rectangular boxes he wound up with (I had my artistic integrity to protect
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