SoundEasy V28 released - ANSI-CTA-2034 automatic measurements

[soongsc]

Each table top will have 6 M8 T nuts to allow securing your own stand on the table. As shown here is an idea to slide the extrusion along the rail nuts secured loosely to the T nuts so that the rail can slide for fwd&aft adjustment. Longer extrusion rail nuts are preferred for a smoother slide.

[bohdan]

Hi George,

The idea of having embedded T-nuts for secure attachment of a loudspeaker supporting structure seems quite good.

Otherwise, one would solely rely on balancing the loudspeaker on the turntable. This is particularly helpful in “vertical polar measurements”, where the loudspeaker needs to be placed on it’s right side, with the microphone facing the tweeter (typically). In this situation, the loudspeaker can be easily unbalanced.

Give that the ceiling-to-floor distance is typically 2.5 meters, performing DIY in-room SPL measurements would optimize FFT windowing when the loudspeaker is placed 1.25m from the floor. This would call for the supporting structure + turntable height to be around 120cm.

Will you be providing such structure with the turntable as an option to purchase?.
If yes, do you have the costing?.

Best Regards,
Bohdan

[soongsc]

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.

[soongsc]

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.

[soongsc]

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:

[bohdan]

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

[soongsc]

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.

[soongsc]

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.

[augerpro]

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.

[bohdan]

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

[augerpro]

like this

[soongsc]

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.

[soongsc]

like this

I would do it like this if I had to: Extend base, add two structure members.

[augerpro]

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.

[soongsc]

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.