In that case, just a big pack of damping material around it is a very simple fix
I think Erin also does that, because even the Klippel system seems to have issues with reflections.
When I made my own mic many years ago (top one), I was actually planning to make the mount as well as XLR plug out of one piece.
That is not so super hard to do even with basic tools (although we had acces to a lathe back in the days).
I noticed that these mounts create quite a lot of reflections as well.
But yeah these things quickly become a very fancy solution, while the alternative is so super simple and effective.
I found that by chaining the PWM setting in the Tic control panel I was able to get rid of most of the whine the stepper made from current chopping when it was holding position.
The reflections from the microphone and the stand are not specific to the Weinreich / Klippel method. If we can get anechoic data apart from some tiny echoes from the microphone / stand that would be a massive achievement. Don't get hung up on the microphone / stand echoes.
I don't think it is much of an issue. Erin did a video where he showed the best method he could find to minimize them. Basically a Tube with an inner diameter that held the mic body and the XLR in a slip fit.
Photography tube and clamping systems should work well. and if there are diameter differences heatshrink tubing or even a few layers of tape can make up the differences and allow a proper sliding fit.
I think this needs reiterating.
Get that Octave + Arduino code into a nearly working range and I’ll do a 3d mechanical concept model that’s easily modifiable, capable of disassembly, and doesn’t cost a lot.
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I'm very interested in that mechanic concept. I'm currently looking into 3D printer / CNC parts to put something together, but I'm a bit lost at the moment. First I tried to put all motors close to the speaker and route belts everywhere in order to limit the weight of the boom, but I dumbed down and still find it difficult. It's all new to me. Also, getting all I (think I) need is not easy. Amazon and the like have a lot, but shipping is quite expensive and somehow I end up with n suppliers for n items.
On the other hand, <bold statement>I think I will get any stepper+controller solution to work with Octave, Python, C++, ...</bold statement>
On the other hand, <bold statement>I think I will get any stepper+controller solution to work with Octave, Python, C++, ...</bold statement>
I’ll look into motors (drivers/shield and power supplies) for you to get 3 motors up and running (and at fairly low-cost). Give me the weekend for that info..
I’m thinking .9 degree stepper motors for fine motor control with discreet steps (ex. 400 .9 degree steps = 360). Probably Nema 14 for the vertical and Nema 17 for the inward/outward & rotational axis’s. More torque will be needed for the rotation, but not a lot more considering that you won’t be moving around more than about 16-18 pounds.
Micro-stepping is key here.
Normally I would be able to help with the design, but we recently moved.
So the house is still a total mess (can't even find my tools) and I am buried with work atm
I already have a rotating table with a large stepper with a tic controller. Works like a charm. I hope to reuse that. I even have a second tic that I ordered accidentally.
We only need to know the position with 3mm accuracy. The measurement positions themselves are not that important. Even 'steps' of 5 cm are fine as long as the result has an accuracy of 3mm. Do you understand what I'm trying to say? It's getting late...
But let's see what you come up with
We only need to know the position with 3mm accuracy. The measurement positions themselves are not that important. Even 'steps' of 5 cm are fine as long as the result has an accuracy of 3mm. Do you understand what I'm trying to say? It's getting late...
But let's see what you come up with
There was a discussion of the reflections off the mic stand over in the parallel (universe) discussion at Audio Science Review. I’m not hung up on those reflections as the biggest problem to be solved, but if they can be reduced without a lot of effort, why not? I think it makes sense to change the mic’s radial position by moving the mic relative to the vertical mic support, rather than by moving that support radially, so that the sound field separation can at least partially remove those reflections. Doing so might even be easier to implement, at least with the turntable-based rotation scheme I’m envisioning.
I think the OpenBuilds v-slot aluminum extrusions and matching wheels look like the best bang-for-the-buck. The 40 mm cross section can be bought in lengths up to 2 m, which is of interest to me because I have some very tall speakers I’d like to measure. Of course everyone can come up with their own customized solution to match their own needs. Just sharing where I’m leaning based on the discussions so far.
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I think the OpenBuilds v-slot aluminum extrusions and matching wheels look like the best bang-for-the-buck. The 40 mm cross section can be bought in lengths up to 2 m, which is of interest to me because I have some very tall speakers I’d like to measure. Of course everyone can come up with their own customized solution to match their own needs. Just sharing where I’m leaning based on the discussions so far.
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In that case, I would rather kill multiple birds with one stone.
When I was designing and working on my own build microphone, I realised that the entire concept of standard microphones is just not ideal.
With moving the microphone, I assume you mean rotating?
If so, that assumes that the mic has perfect omnidirectional behaviour.
Depending on the type, they only have that up to 10-15kHz. (Some cheap ones even a bit lower)
By moving I mean translating and rotating so that the mic is always pointing at the vertical axis of rotation of the scanner. I wouldn’t take on the complexity of trying to point the mic up or down to keep it always aimed at the same point in space—at least not until it was demonstrated that useful results require that extra degree of freedom.
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If I were still an acoustic researcher, I would look for a way to eliminate room errors while rotating the speaker rather than having a fixed speaker - it is so much easier that way. It has to be possible since the speaker and mic remain in a fixed situation. If one were to model that situation than it could be removed from the results. It is an interesting problem, but I am just not up to doing that kind of analytical development anymore. I have trouble remembering my name let alone how to model a room.
I am the same way.
Which reminds me,
From a practical point of view, how much free space does a moving mic aka Klippel system needs in general?
If there is reflections from the mic stand, they will always be there. It is my supposition that they would get filtered out no?
I am 100% in the camp that we try the spin the loudspeaker and offer up the mic at different heights vertically and see what we can accomplish.
If any proving out it required I am more than willing to do a true anechoic versus what we can cobble together. If I use my large ladder I'm anechoic to under 30 hertz. 15 feet up just under 5 metres.