Announcement

Collapse
No announcement yet.

SoundEasy V28 released - ANSI-CTA-2034 automatic measurements

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • soongsc
    replied
    Hi Bohdan,

    The outrigger concept, I guess which was illustrated with the wheels, actually increases the rotation loading. This loading maximum allowable I have not really tested yet. This is due to the rolling resistance, wheel mass, and the arm leverage to the wheels.

    The bearing of the turntable can take up to 150Kg in the vertical direction as provided by the supplier. So it seems we have enough design margin. But the rotation loading originally was calculated at the edge of the turntable with 30Kg. We feel it can take up to 60Kg, but do not know how much margin we have because the original estimation was done by the supplier when they recommended the motor. I do not know what kind of acceleration they based their calculation on. When we start trying to load the table to max, we will know.

    Currently the design is based on our own in-house needs, but we could custom design and ship whatever a customer wants. Or once the maximum loading is tested, the customer can decide to attach their own depending on their specific needs.

    The wheel as you mentioned can be added, and the bottom sliding rail is designed for something like that to add on, large diameter wheel about the diameter of the turntable would work best as it will have less rolling resistance. However, the weight of the wheels and the leverage not needs to be added to the weight calculation.

    As far as back of the speaker. if the speaker gets sooo deep such that the CG will extend outside the edge of the turntable, you could use an additional wheel, it adds more friction and rotating weight.

    Personally, I think tall speakers should take a cylindrical measurement approach because the diffraction edge now gets closer to the mic and kind of pollutes the data because such diffraction will reach the mic earlier than first room reflection, but such will not occur in real world application.

    The curtain rods are for adding the second axis turntable. The full design is supposed to be expandable. But an idea just popped up. Let me see if I can get some wheels to play around with the loading with outrigger wheels. If I can stand no the outrigger, wheels and the table still turns, then this can be added as an option.

    Leave a comment:


  • bohdan
    replied
    Hi George,

    The ”outrigger” concept may require some investigation.

    For a very simple reason.

    The outrigger has the potential to take significant amount of (loudspeaker + rig itself) weight off the turntable. This would almost double the available load spinning capacity of the turntable.

    The outrigger does not have to be placed at the end of the loudspeaker. It only needs to stand far enough from the turntable to prevent the loudspeaker from tipping over – so just past the long wall’s half-way point. Assuming, that the outrigger is rigid enough, this would rest almost the whole weight of the loudspeaker on the outrigger. The turntable role would be to driver the outrigger.

    Perhaps, the wheels of the outrigger may need to be replaced by just a single wheel on a swivel, and the wheel would have to be attached to the turntable by a rigid rod, or some other rigid means, so that the outrigger does not tip forward/backwards.

    Even for the horizontal polar measurements ( loudspeaker placed in a normal vertical position), you could attach to the turntable (behind the speaker), a small outrigger with a platform, to support the loudspeaker’s weight at the back. This way, no need for the “curtain rod”.

    Anyway, does this make sense to anybody?.

    Best Regards,
    Bohdan

    Leave a comment:


  • soongsc
    replied
    Originally posted by augerpro View Post
    I have some very tall speakers, 1.5m at least, where this has been an issue if I wanted to rotate the speaker too. You would still need an outrigger or your whole setup would topple over.
    True, that is why designs are made for easy customization add-on. I would recommend checking #15 post to determine what you might need.

    Leave a comment:


  • augerpro
    replied
    I have some very tall speakers, 1.5m at least, where this has been an issue if I wanted to rotate the speaker too. You would still need an outrigger or your whole setup would topple over.

    Leave a comment:


  • soongsc
    replied
    Originally posted by augerpro View Post
    like this
    I would do it like this if I had to: Extend base, add two structure members.

    Leave a comment:


  • soongsc
    replied
    I would kind of ask how tall one would want the measurement center off the ground? With the current design, we could probably do a speaker that is one meter tall from the measurement center. This is quite in line with the normal listening hight of the ear.

    Leave a comment:


  • augerpro
    replied
    like this
    Attached Files

    Leave a comment:


  • bohdan
    replied
    Originally posted by augerpro View Post
    I wonder if, for long speakers on their side, you could make an outrigger of sorts, with wheels. I was actually thinking about buying an IV holder off Amazon to do this, but those are weight limited. You could make these very strong.
    Hi,

    For a mechanically-inept people like myself, could you make a drawing?

    Best Regards,
    Bohdan

    Leave a comment:


  • augerpro
    replied
    I wonder if, for long speakers on their side, you could make an outrigger of sorts, with wheels. I was actually thinking about buying an IV holder off Amazon to do this, but those are weight limited. You could make these very strong.

    Leave a comment:


  • soongsc
    replied
    Here is the update of the single axis turntable rig. The distance between the speaker supporting arms are made smaller so as to hold smaller speaker. And the position is adjustable making it easier to center a tweeter to the rotation axis if so desired. Note that weight balance is used so the speaker can balance on the arms, and an adjustable curtain rod is used to support the weight. We hope to find a simple solution to build this into the rig to cover the full range of the height adjustment. The weight of the rig will run between 8~9 Kg. About the weight of the table itself. Additionally, we will be cleaning up the design a bit by changing the current angled brackets to a different one with cleaner outline.

    Leave a comment:


  • soongsc
    replied
    Hi Bohdan, I am trying to fine tune the design to make it possible to adjust the distance between the arms making it easier to hold the speaker upright, as well as smaller speakers. When I get that done, I can weight it.

    Leave a comment:


  • bohdan
    replied
    Hi George,

    The rig looks interesting. This is what I have been waiting for.

    It's acoustically transparent, which is exactly what is required for these measurements. And allows certain degree of adjustments left-right and up-down.
    My turntable does have the holes in the bottom plate. I guess, you can attach a larger plate to it for increasing stability of larger loudspeaker measurements.

    How heavy is the rig?.

    Anyway, this is exactly what I was looking for. I had to do a lot of gymnastics and balancing when I was doing vertical measurements on my example speakers.

    Best Regards,
    Bohdan




    Leave a comment:


  • soongsc
    replied
    Here is an example how a single turntable can be used for vertical polar measurements. This should be able to cover most home speaker sizes. If your speaker is pretty tall, it may also be possible to add a counterweight for balancing as below:

    Leave a comment:


  • soongsc
    replied
    For people whom might want to expand the table base to suite their specific needs, 6 holes on the bottom plate are provided to allow attaching a board to the bottom. The dimensions of hole location on the base plate is shown below: Anyone can add a large board by making holes with M8 or similar T bolts that align with these. When doing measurement in an anechoic chamber, I would suggest a configuration which will be shown in later posts.
    Click image for larger version

Name:	Screen Shot 553.png
Views:	187
Size:	416.3 KB
ID:	1486604

    Leave a comment:


  • soongsc
    replied
    Hi Bohdan, Once I finish the two axis rotation design, then I will calculate the cost. The long post size (about one meter long), I would propose the user purchase individually. This is due to the risk of those getting bent during shipping. Additionally, these posts would have one end threaded to accept M8 screws. The other parts I can provide in a smaller package. Below is the basic structure upon which a single axis operation stand can be configured by shifting the upper horizontal bar up, and adding two arms out to hold the speaker. As long as the cg is within the two vertical bars and not exceed the table diameter in the fwd/aft positioning, single axis operation can be used without the base expansion. Personally, I still would recommend the base expansion just to not worry about cg positioning too much.

    The H frame has a sliding range of about 25 cm laterally, and a range of about 28cm longitudinally. Here on, I will be adding arms to demo single axis operation, then adding base expansion, finally the second axis.
    Last edited by soongsc; 05-25-2022, 05:50 AM.

    Leave a comment:

Working...
X