As some of you might have gathered, I'm in the process of building Troels Gravesen's new The-Loudspeaker-III.
I'm currently extensively modeling the speakers in Fusion 360 (a CAD software) to try a few different designs (different colors, veneers, speaker stands) to tailor them to my taste.
On his website, Troels states the following: "Due to the NSD1095/XT1086 horn delivering the same frequency response regardless of front panel design, there is a great deal of freedom in this construction. Only key elements are the horn tilt and the displacement of the midrange driver relative to the horn and keeping the midrange front panel some 230 mm height with driver in middle. So stick to the upper front panel design! Almost anything else you can do to your liking and it will perform as intended."
I have trouble understanding what this 'great deal of freedom' is.
I get that I shouldn't mess with the horn tilt, nor the midrange driver being on top of the horn, and the midrange front panel being 2300mm.
* Can I flush mount the drivers to make it look a little cleaner?
* As the midrange has its own cabinet, can I detach it from the rest of the speakers and have it resting on top? This would allow me to build two different cabinets and increase the possibility to fine tune the speakers visually.
I'd rather ask here than keep bothering Troels with stupid questions every few days.
I'm currently extensively modeling the speakers in Fusion 360 (a CAD software) to try a few different designs (different colors, veneers, speaker stands) to tailor them to my taste.
On his website, Troels states the following: "Due to the NSD1095/XT1086 horn delivering the same frequency response regardless of front panel design, there is a great deal of freedom in this construction. Only key elements are the horn tilt and the displacement of the midrange driver relative to the horn and keeping the midrange front panel some 230 mm height with driver in middle. So stick to the upper front panel design! Almost anything else you can do to your liking and it will perform as intended."
I have trouble understanding what this 'great deal of freedom' is.
I get that I shouldn't mess with the horn tilt, nor the midrange driver being on top of the horn, and the midrange front panel being 2300mm.
* Can I flush mount the drivers to make it look a little cleaner?
* As the midrange has its own cabinet, can I detach it from the rest of the speakers and have it resting on top? This would allow me to build two different cabinets and increase the possibility to fine tune the speakers visually.
I'd rather ask here than keep bothering Troels with stupid questions every few days.
I think that "freedom" here means the response of the horn doesn't depends much on the baffle geometry, due the relative high directivity it provides.
It sounds like a good idea to mount them on a less awkward baffle. You may want to tweak the crossover to account for the distances and the change in response.
I honestly don't think I have the knowledge to get into that, nor the measurement equipment.
If I make 100% sure to keep the drivers aligned like this, compensating for any change I make, I won't need to tweak the crossover, right?
The weak point, for me, is the tweeter horn that sits in the woofer chamber.
And, oh yes, the electronic should be detatched from the "rumbling body" of the woofer chamber.
The crossover too, it shouldn't stay in the enclosure.
At this point, putting the midrange in its own chamber is an easy game...!
And, oh yes, the electronic should be detatched from the "rumbling body" of the woofer chamber.
The crossover too, it shouldn't stay in the enclosure.
At this point, putting the midrange in its own chamber is an easy game...!
I mentioned two problems, the distance and the response due to the baffle shape.
So I'm wondering what differences are you talking about? It's possible that you can deal with some changes.
What is the upper crossover frequency?
So I'm wondering what differences are you talking about? It's possible that you can deal with some changes.
What is the upper crossover frequency?
I don't mind the tilt and the midrange baffle being recessed.
I was wondering If I could flush mount the drivers and change the front baffle dimensions to make it look a little better?
I was wondering If I could flush mount the drivers and change the front baffle dimensions to make it look a little better?
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Flush mounting isn't likely to make too much difference, particularly given the frequencies involved.
Changing the baffle might also not be too critical, lots of variables so too much to guess but I think the baffle might be having an effect on the tweeter lower frequency dispersion and I wouldn't be trying to run it open.
Changing the baffle might also not be too critical, lots of variables so too much to guess but I think the baffle might be having an effect on the tweeter lower frequency dispersion and I wouldn't be trying to run it open.
I don't plan on running it open, it has a height of 220mm on Gravesen's design, I'd like to make it around 250mm while keeping a 6° tilt to make it visually more serene, less close to the edges.
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Unless I'm stupid, it's not specified any where on Gravesen website.
Perhaps my original questions understate how little I know about cabinet design.
On each and every pages of Gravesen's website, it is said that altering the front baffle dimensions will result in having to change the crossover. I do not want to forray into that territory, I want the speakers to sound as Gravesen made them.
What I don't understand is, if I can't alter the front baffle design, what exactly is this 'great deal of freedom'? Because if I can't change the front baffle design, can't change the drivers placement, can't change the horn tilt, etc, it sounds to me like I can't actually change that much.
At times like this you might want to estimate. Since it is an 8" driver, if it were me I might just cross it a little below 2kHz. A quarter of a wavelength there is around 5cm. If you want to keep changes below about that much... Keep in mind that some kinds of change might have a bigger effect.
Not sure about that. Quarter wavelength difference can lead to 6dB less summed output on axis at Xover frequency. Far off axis this issue is nonexistent of course, but I thought I’d better add this. I’d keep the difference no more than 2cm.
I agree, it has to come with common sense. Different kinds of change do very different things and to different degrees. However to begin you want to know what dimension is acoustically significant in theory.
Troels further explained what was possible with the cabinet design. Here's my take on it. It doesn't change much, i.e. no need to tweak the crossover. It looks a million time better to my eyes. Here it is with and without the optional midrange driver grill. They're now in a separate cabinet standing on top on the bottom cabinet.
Calmant,
I most likely will use your 2 piece design as the basis for building my own but think I will simplify construction by cutting all fronts, backs, tops, bottoms the same width (380mm) out of 1" baltic birch, the braces and the slot top board the same width but using 3/4" baltic birch. The sides (1" baltic birch) will extend 1"forward of the front panels and edges polished showing the veneers. In between the sides I can mount a 1/2" thick frame for the grill cloth with 1/2" clearance for the drivers. This will also save me the trouble of flush mounting the drivers. Construction should be simple with butt joints augmented with dominoes and battens. I will most likely contract out the cutting of the width of the 30 some panels (for a stereo pair) to a cabinet builder to maintain tight tolerance. Since they are all the same width the cost should be low. I mean to isolate the horn from the bass driver with a simple box, Well, thats the plan.
Cheers,
Vanko
I most likely will use your 2 piece design as the basis for building my own but think I will simplify construction by cutting all fronts, backs, tops, bottoms the same width (380mm) out of 1" baltic birch, the braces and the slot top board the same width but using 3/4" baltic birch. The sides (1" baltic birch) will extend 1"forward of the front panels and edges polished showing the veneers. In between the sides I can mount a 1/2" thick frame for the grill cloth with 1/2" clearance for the drivers. This will also save me the trouble of flush mounting the drivers. Construction should be simple with butt joints augmented with dominoes and battens. I will most likely contract out the cutting of the width of the 30 some panels (for a stereo pair) to a cabinet builder to maintain tight tolerance. Since they are all the same width the cost should be low. I mean to isolate the horn from the bass driver with a simple box, Well, thats the plan.
Cheers,
Vanko
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