My first project is a 4 way speaker...

[TEK]

Have you tought about making the stands (or "feet") a bit further out from the speaker?
Kindof this: https://www.marten.se/coltrane/

Wonder if that would give a even more solid impression of the base.
But it's just an idea.

[cochinada]

Have you tought about making the stands (or "feet") a bit further out from the speaker?
Kindof this: https://www.marten.se/coltrane/

Wonder if that would give a even more solid impression of the base.
But it's just an idea.

Yes, I have but unfortunately that would not fit in the very limited footprint I have.

[cochinada]

Some progress with the stands and plaques:

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I hope that after powder coating the stands those irregularities that we can see on the cut will not show.

[TEK]

I have no experience with powder coating, but for other types of paint the rule is kindof that if you can feel it you will see it after painting.
Then normally it is a primer/filler that fixes the small irregularities.

I think I would have discussed this with the one going to do the powder coating. If that's not an option I would have found water and sandpaper and gone at it to get it closer to perfect first.

[cochinada]

Yep. I talked to the guy that made these parts and he's going to try to smooth everything as much as possible.

[cochinada]

Hello guys. Sorry for this long period without news but I'm having some personal problems and the motivation is not that great at the moment. Anyway life goes on and the project is moving forward.

Initially there were some quality issues with the 30mm boards so my carpenter decided to glue two plates of 15mm to come up with 30mm as those didn't show the defects on the surface as the thicker ones.


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[cochinada]

More pictures of the pieces being cut and piled at the end.


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[meb46]

Awesome update... you will be the envy of all on the forum this weekend... I love the sight of freshly CNC'd speakers ready for assembly... I would struggle not to pull an "all-nighter" to see them come together!

Happy weekend!!

[TEK]

Whooaa!
That's some speaker! Really nice to see those drawings bering materialized into something real.
Seems to be quite a job building those, even with cnc'ing the parts!

Sorry to hear there are other issues affecting your motivation. Hopes that gets sorted out.

[deewan]

Great looking work so far. I love it!!! Keep the pictures coming!

[Steve Manning]

Now that's the quick and easier way to make a speaker ..... very nice so far.

[JonMarsh]

That's an impressive build that's coming together- I'm certainly jealous of guys that have access to tools like this! :T Makes me feel like I'm working with just an old carpenter's saw and a beat up old B&D drill in comparison! That's quite a bit of shop space to have access to, also!

Please keep the pictures coming- and sorry about whatever personal issues you've had- hope that's sorted, now.

[cochinada]

Thank you all for your kind words. Things are getting better. Also my carpenter has told me that he's expecting to finish the boxes this week so the time has come for me to think about how am I going to measure the thing.

For your information my measuring tools are Omnimic and DATS V2 and lots of inexperience, therefore I'm counting on you to give me some tips.

I've read the white paper from Jeff Bagby some while ago "How to Achieve Accurate In-Room Quasi-Anechoic Free-Field Frequency Response Measurements Down to 10 Hz" and someone has also lend me the famous "Loud Speaker Design Cookbook" by Vance Dickason but I have not read it yet.

With a lot of hard work I can assemble the whole box and measure one driver at a time if needed. The question is how should I do it? For instance, should I place the mic at 1m from the tweeter center or at 2.5m which will be more or less the distance to the sweet spot or neither option? Intuitively for me it makes sense to leave the mic always on the same position and measure each driver at a time. I guess this is why they mention that the design listening axis is the tweeter, and the design distance is 2.5 meters. However, if I keep the mic this far I guess I will have to face the whole shebang of room reflections which is not good and there is also the issue with the low frequencies...

In a nutshell I'm lost here and would appreciate a lot to hear your advice and guidance.

Thank you in advance.

[JonMarsh]

There a few different ways you could approach this.. but what really counts is getting the data that you can use to prepare a crossover network. Near field data is interesting, for what it shows about the driver, but it won't be representative of what you need for the design. For a larger speaker system, 1 meter and leaving the mic in the same spot will present problems for representing the far field response for the complete system. For a two way book shelf, 1 meter works ok - not that much angular offset. There is also the matter of boundary loading versus cabinet size and how far away you have to be to have accurate data.

Far large systems, I prefer a 2 to 2.5 meter measurement, and when possible do it outdoors with nothing else nearby. If I HAVE to do the measurements indoors, that's when I get out all the sound baffles, heavy comforters, etc, and drape anything that can cause nearby reflections to interfere with the direct sound from the speaker.

You should measure each driver separately, but you should ALSO measure all of the drivers together, or do so in pairs, at least, because then you can compare this raw measurement to what you get in LspCAD or Soundeasy or whatever you use for crossover design, and adjust the driver delays until the simulated response in the tool for multiple drivers matches the measured response in the actual cabinet. It's easier to do that with just two drivers at a time, though with a three way it's not a big deal to do all of them at once, to get the relative acoustic offsets. For a four way, you may be pushing your luck to do all of them together.

[cochinada]

Thank you very much JonMarsh.

There a few different ways you could approach this.. but what really counts is getting the data that you can use to prepare a crossover network. Near field data is interesting, for what it shows about the driver, but it won't be representative of what you need for the design. For a larger speaker system, 1 meter and leaving the mic in the same spot will present problems for representing the far field response for the complete system. For a two way book shelf, 1 meter works ok - not that much angular offset. There is also the matter of boundary loading versus cabinet size and how far away you have to be to have accurate data.

And what if measure both the Far-Field and Near-Field of each driver by carefully placing and adjusting the mic distance over each, taking also into consideration the baffle width and corresponding diffraction and then blend all these curves together? Then I would have one curve per driver but since they have different sizes, if I place the mic at different distances in order to respect the limits of Far and Near Field which differ with the size of the drivers than I would have the additional problem of different sound levels I guess. How would I know how much I should attenuate the loudest curves, so to speak? The more I think about this the more daunting this task seems to me. 8O

Far large systems, I prefer a 2 to 2.5 meter measurement, and when possible do it outdoors with nothing else nearby. If I HAVE to do the measurements indoors, that's when I get out all the sound baffles, heavy comforters, etc, and drape anything that can cause nearby reflections to interfere with the direct sound from the speaker.

There is no way I can measure these monsters outside as I live in a flat. My room is also on the smallish side and the only thing I can move away is a little table in front of the couch.

You should measure each driver separately, but you should ALSO measure all of the drivers together, or do so in pairs, at least, because then you can compare this raw measurement to what you get in LspCAD or Soundeasy or whatever you use for crossover design, and adjust the driver delays until the simulated response in the tool for multiple drivers matches the measured response in the actual cabinet. It's easier to do that with just two drivers at a time, though with a three way it's not a big deal to do all of them at once, to get the relative acoustic offsets. For a four way, you may be pushing your luck to do all of them together.

I'm confused. I understand that the driver delays have to be measured somehow and this taken into consideration under my crossover design simulator which will be VituixCAD but I don't understand how measuring all at the same time, that is with no crossover yet will help. I will have a very strange curve with all responses added. 8O

[JonMarsh]

Thank you very much JonMarsh.



And what if measure both the Far-Field and Near-Field of each driver by carefully placing and adjusting the mic distance over each, taking also into consideration the baffle width and corresponding diffraction and then blend all these curves together? Then I would have one curve per driver but since they have different sizes, if I place the mic at different distances in order to respect the limits of Far and Near Field which differ with the size of the drivers than I would have the additional problem of different sound levels I guess. How would I know how much I should attenuate the loudest curves, so to speak? The more I think about this the more daunting this task seems to me. 8O



There is no way I can measure these monsters outside as I live in a flat. My room is also on the smallish side and the only thing I can move away is a little table in front of the couch.



I'm confused. I understand that the driver delays have to be measured somehow and this taken into consideration under my crossover design simulator which will be VituixCAD but I don't understand how measuring all at the same time, that is with no crossover yet will help. I will have a very strange curve with all responses added. 8O

Yes, you'll have a very strange response, but if you load all of the individual responses into whatever crossover tool you use (should be minimum phase measurements at that point, may require post processing by your measurement tool) then they will ONLY match the very strange response you get measuring them all IF you have the time delay offset of each driver set correctly. You can estimate them initially by voice coil offsets, but it's he actual acoustic time offset that counts.

[TEK]

There is no way I can measure these monsters outside as I live in a flat. My room is also on the smallish side and the only thing I can move away is a little table in front of the couch.

What about bringing them over to someone else? Or at your carpenders area?
Or borrow a compressor and drive out in the bush with the equipment ;-)
For a large 4-way I would imagine that it will be very difficult to get good measurements in a small room...

[Juhazi]

My humble suggestion is to (at least for the beginning) use minidsp 4x10HD and make them active (multichannel amps needed too). Not easier but reversible, can take care of different sensitivities, delays, not so afraid of low impedance etc. You can start in your room and get some sound out of it right away. Expect at least few months/years for progress as your skills get better. Even the "subwoofer" part should be run through minidsp to get best possible acoustic match to rest of the system.
.
When aprropriate acoustic slopes have been found one can consider trying to reiterate that to passive xo.

An example here (dipole but the basic procedure is the same) http://www.hifizine.com/2010/12/prot...e-minidsp-2x4/

[5th element]

http://www.mediafire.com/download/7dsikmz44lnf7br/measurement+guide.pdf

Will give you a good starting point for making usable measurements. There are other guides out there of course

[cochinada]

Thank you all for your helpful suggestions!

@5th element,

I just finished reading your wonderful guide which cleared most of my doubts and in light of which I understood how to put in practice what JonMarsh wrote at the end.
I'm just wondering why we don't have to enter the Radius of the drivers, including the tweeter for instance. Aren't we assuming this way to have an ideal radiating source point which will be less faithful than the true case of a driver?
Considering the angle, is this in the vertical plan relative to the Y=0 position? If so, then I assume that dY=180mm and distance=1m are the two sides of the right triangle and the response you measured was indeed off-axis for the tweeter and LspCAD will know this fact.

@TEK,

I'm afraid none of these options are possible as it would take some transportation logistics, probably many hours or even days for being able to measure all things in a quite environment which I don't have or doesn't depend on me.

@Juhazi,

That's very interesting but I cannot afford to spare months or even years to get this thing finished.

[BobEllis]

Nothing says your speakers aren't "finished" while active.

Many of us do just that. For me it's easier to dial in the desired transfer function electronically than dealing with the complex variable impedances of the drivers. That's a driver behind the complexity of many of Jon Marsh's crossovers. (The other main driver being perfectionism).

My Ardent inspired build is heading towards a mix of passive mid to tweeter and active woofer to mid and sub to main. I will start out fully active, though. Take advantage of your mini DSP at least single channel to dial in your desired transfer functions. That will save time in the passive phase with less trial and error.

[TEK]

That's a lovely part of the project, when your design is beeing materialized in real life, and the final touches is getting done so that you can really start to get a good impression of what they will look like :P

I must admit, when I'm in that face, and forward - I often find myself "wisiting" my build, taking a look at it and feel the wood - even if I'm not doing any building that day ops:

[cochinada]

That's a lovely part of the project, when your design is beeing materialized in real life, and the final touches is getting done so that you can really start to get a good impression of what they will look like :P

I must admit, when I'm in that face, and forward - I often find myself "wisiting" my build, taking a look at it and feel the wood - even if I'm not doing any building that day ops:

Believe it or not I haven't yet see the boxes live as my carpenter's shop is a little far from my home so I can't wait to see if they are up to my expectations which are very high indeed. For me, almost as important as how they will sound is how they will look as I put a lot of attention to details so everything could be as close to perfect as possible. So, let's wait and see if after the veneering I will be completely satisfied or not.

[deewan]

Those cabinets look so good I want to build them even if I don't have the components allowing them to play music. The cabinets can be a beautiful piece of furniture in my stereo room.

However, based on the attention and detail of this build so far I am sure once you have these things up and running they will sound as impressive as they look!!!

[---k---]

Wow, those are beautiful monsters. Looks like they are coming along great.

[5th element]

Woweee! Good job!

[TEK]

What veneer will be used, and how will the veneer be finished?

[JonMarsh]

Beautiful looking cabinets- I wonder what they will weigh when loaded with all the guts? Any pre-calculation done for that?

[cochinada]

Thank you guys. This won't have any extra veneer. That's one of the reasons I chose Baltic Birch instead of MDF as I like and want to preserve that look of multiple sandwiches on the cross sections like in the round corners for instance. The varnish will be 100% natural. I have yet to confirm whether it will be bee wax or something else. I often confuse veneer with varnish and that can cause some confusion. ops:

Concerning the cabinets, the empty boxes should weight 90.3 kg (199 lbs) from my calculations and with all the drivers, crossover components, feet and spikes and all the hardware I estimate a total of 148kg (326 lbs) each.

[cochinada]

Strange things happen. My carpenter has just told me that each assembly weights 110 kg instead of 90.3 kg. So either he used a whole lot more glue or more likely the density of this Baltic Birch is not 680 kg/m3 but about 815 kg/m3!
Anyway this means each cabinet will weight about 168kg.

[Face]

Strange things happen. My carpenter has just told me that each assembly weights 110 kg instead of 90.3 kg. So either he used a whole lot more glue or more likely the density of this Baltic Birch is not 680 kg/m3 but about 815 kg/m3!
Anyway this means each cabinet will weight about 168kg.

I hope you've been hitting the gym.

[cochinada]

Hey guys I need to sort one small problem. I have the cabinets in my home right now but the thing is that when they are assembled they are not totally motionless. In other words, there is a little movement between each box. So what I need are some suggestions in order to minimize or eliminate this movement. My carpenter suggested a few drops of silicone to act like shock absorbers and also to make them stick tighter to each other when assembled.

[JonMarsh]

with all the drivers, crossover components, feet and spikes and all the hardware I estimate a total of 148kg (326 lbs) each.

Yowsa! That's a lotta stuff! :W :B

Are you going to assemble them where they will live? Not planning on moving for a while? I did a system back in the late 90's that was probably about 210 lb net- that was too much for me! My Isiris are bordering on that, too, one reason I haven't finished moving them back to my other domicile for final assembly and tweaking.

[---k---]

That is a little disappointing based on the level of effort you put into these. BUT, probably shouldn't be that shocking. Plywood is never perfectly flat and it can warp easily depending on how it is stored and even the weather. Just a slight, not visible bow, could lead to this.

Blu Tack http://www.blutack.com/ is frequently recommended between speakers and stands to minimize vibrations. It's just poster putty, but some corners of the web think of Blu Tack as a magical tweak that will remove veils, enhance your bass and promote world peace (I exaggerate). I'm not sure if Blu Tack has magical properties beyond generic poster putty or silicone. Using this would be similar to what your carpenter is suggesting.

The other thing I could see doing would be to drill holes between the boxes on the interior and thread bolts between them to clap them together tight. If the boxes were lighter, I would say this was a must to make sure an accidental bump didn't knock them apart, but that might not be an issue here. I'd probably go this route in addition to the Blu Tack.

[Steve Manning]

I was going to suggest the same as Ryan with the bolt idea, another option that I did with my equipment rack and a set of speakers, is to float the parts on rubber ball bearings.






The rubber balls are 5/8" in diameter and the holes that they sit in are 1/2" in diameter. Works very well keeping up with wood movement and very stable, not that they would hold up to small children and their antics, but other wise I've had no problems. Got the balls from McMaster Carr.

[Jonasz]

Yep, put something soft between them, should be better than solid couplings. Should also imho be soft feet not spikes under them to isolate them from the floor.

[cochinada]

Yowsa! That's a lotta stuff! :W :B

Are you going to assemble them where they will live? Not planning on moving for a while? I did a system back in the late 90's that was probably about 210 lb net- that was too much for me! My Isiris are bordering on that, too, one reason I haven't finished moving them back to my other domicile for final assembly and tweaking.

One never knows what future reserves but in case I'll move the most important thing is to keep the cabinet modular so it can be separated for transportation. That was actually anticipated from the beginning as soon as I started to realize how much these beasts would weight. You're system from the 90's is not that far from mine net (240 lb) and yes it is still quite an obstacle. I plan to assemble the finished boxes on the final spot but for now and for measuring purposes I will place one along the major axis of my room as far from the walls and furniture as possible and because I'm not going to mount the big woofers as they will be active this will save some precious weight.

That is a little disappointing based on the level of effort you put into these. BUT, probably shouldn't be that shocking. Plywood is never perfectly flat and it can warp easily depending on how it is stored and even the weather. Just a slight, not visible bow, could lead to this.

Blu Tack http://www.blutack.com/ is frequently recommended between speakers and stands to minimize vibrations. It's just poster putty, but some corners of the web think of Blu Tack as a magical tweak that will remove veils, enhance your bass and promote world peace (I exaggerate). I'm not sure if Blu Tack has magical properties beyond generic poster putty or silicone. Using this would be similar to what your carpenter is suggesting.

The other thing I could see doing would be to drill holes between the boxes on the interior and thread bolts between them to clap them together tight. If the boxes were lighter, I would say this was a must to make sure an accidental bump didn't knock them apart, but that might not be an issue here. I'd probably go this route in addition to the Blu Tack.

Yes, for a perfectionist this world is not a walk in the park but we have to adapt I guess. Don't get me wrong when I mention some movement. Is not like I'm talking about the Tower of Pisa. The top box moves about half a millimeter the most if I push it hard. With the drivers mounted and the correspondent 42 lb extra this would be more stable for sure.

Now that you mention it I've heard about this famous blutack some years ago. You're not exaggerating that much. I remember people raving and completely crazy about it. But since I normally don't go with the flow I will probably stick with plain old silicone.

The reason I'm not considering screwing the boxes together is because of what I mentioned earlier and as you said, unless an elephant in heat decides to invest and attach my speakers I feel confident they won't tumble.

[cochinada]

Thanks guys. Something soft like rubber of silicone seems the best option so far as this would for sure maximize the friction between the boxes.

The spikes are already bought and I'm thinking the best way to mount them due to the weight of the thing...

[TEK]

Hey guys I need to sort one small problem. I have the cabinets in my home right now but the thing is that when they are assembled they are not totally motionless. In other words, there is a little movement between each box. So what I need are some suggestions in order to minimize or eliminate this movement. My carpenter suggested a few drops of silicone to act like shock absorbers and also to make them stick tighter to each other when assembled.

As these are made by a living and moving material I think that should be expected as long as they are not glued together.
You describe it as "a little movement". I think that you should follow you carpenders advice, that should fix the issue and with the weight of these I'm confident that movement will not be a problem.
As each speaker is in two parts, each part should be approx 84kg. Compare that to almost any commercial sub and you will still have a lot more weight and stability!

Be sure to let the silicon dry before assemblomg the cabinets - at least if you are planning on beeing able to separate them at a later time.

[cochinada]

As these are made by a living and moving material I think that should be expected as long as they are not glued together.
You describe it as "a little movement". I think that you should follow you carpenders advice, that should fix the issue and with the weight of these I'm confident that movement will not be a problem.
As each speaker is in two parts, each part should be approx 84kg. Compare that to almost any commercial sub and you will still have a lot more weight and stability!

Be sure to let the silicon dry before assemblomg the cabinets - at least if you are planning on beeing able to separate them at a later time.

For sure I won't forget that

Just one correction: each speaker is made of 3 boxes and not 2. The bottom one is the heaviest with 87 kg. The MTM weights only 16 Kg and the top box almost 65 kg.

[---k---]

Be sure to let the silicon dry before assemblomg the cabinets - at least if you are planning on beeing able to separate them at a later time.

That is sort of why I like the Blue Tack idea. No waiting to dry. No excess thickness. It will squeeze out to almost zero thinness where not needed and is easy to remove at some point in the future.

[cochinada]

That is sort of why I like the Blue Tack idea. No waiting to dry. No excess thickness. It will squeeze out to almost zero thinness where not needed and is easy to remove at some point in the future.

Interesting, particularly about the almost zero thinness although it says it is ideal for non-porous surfaces and I wonder if wood will work. Anyway I will see if I can find it in the local store.

[Steve Manning]

Wow ...... very nice:T

[dar47]

I second that! Maybe in another life I could have monsters like that in my house. Another thought is I wonder how long it would take to veneer them, haha

[cochinada]

I second that! Maybe in another life I could have monsters like that in my house. Another thought is I wonder how long it would take to veneer them, haha

Hey!, we live in a world where everything is possible and changes so rapidly that maybe you can. I would be happy to make you a couple of boxes but you would have to pay also for the transportation .

Veneering would not be an easy task for sure, mainly because of the top and bottom rounded all around not to mention the size of the thing and that's why I dropped this option at the very start.

Actually my carpenter made some mistakes as I designed a 30mm chamfer on these tops and he cut a much smaller radius instead. He also forgot to chamfer some edges of the matrix which are visible on the 4th picture, supporting the baffle and made some holes in the wrong places :evil: