Final Stand Construction

Yesterday, the final stands were constructed, obviously marking a major step in the overall project. The one column stand was chosen as the final design due its rigidity. Many of the same steps were taken to build this stand as were to build the prototype of the one column design. However, extra precautions were taken in order to produce a cleaner final product.

When gluing the PVC to the flanges, a less messy and careful approach was taken in order to get as little spill over of primer onto the outer the surface of the flange. Another precaution that was taken was once the wood plates were sanded we were careful not to set them down anywhere that had things that could chip the surface, such as little pebbles. The last thing we did more carefully was lining up the bottom wood plate with the top wood plate. During the prototype construction, we only realized after we had glued the flanges to the PVC that they needed to be lined up so that the cut-outs matched up on either end of the PVC pipe. This time we ran a line from the top flange to the bottom one, so when we glued them on to the pipe, they would be oriented the same way. Once glued on, the center of the wood plates was found in order to make sure the flange was drilled into the correct position.

As stated earlier, the same methods of construction used in the prototype build were used for the final build. This time around we were much more efficient in our building as we completed the final stand construction in two hours compared to four hours for the prototype pair.

Parts List Assembled

Preparation for tomorrow's build was completed today. Logistics for transportation were ironed out and confirmed among group members. A parts list was compiled so that we will be prepared when we purchase any materials that we don't have left over from our prototype build. In addition, we have the proper measurements of the stands from our CAD designs so that we are able to be as efficient as possible in their construction. More details will come in posts tomorrow and Saturday detailing the results of the build and any problems that we encountered.

Planning for this weekend's drafting of the final report was also accomplished, so that we will be able to juggle the coop process and the responsibilities for this class in an effective manner.

Isolation Materials in Fusion 360

As mentioned previously, during our last lab, I spent some time modeling the different materials we will be testing out as our isolation system. These materials will be tested by themselves as well as stacked in layers. The foam, felt, and cork will be laid across the upper plate, covering it completely. The sponge and rubber feet will be placed in the four corners of the upper plate supporting the speaker like legs. Below are pictures of the modeled isolation materials in Fusion 360.

Cork

Felt

Foam

Rubber Feet

Sponge

Below, a possible arrangement of the isolation materials (1/8" cork placed in-between two sheets of 1/4" foam), is pictured.

Week 6 Lab Activities

With the prototype and preliminary testing phase of our project complete, we spent the duration of today's lab period planning for final push of the term: the construction of the final stands/isolation system and the rounds of subjective and objective testing to demonstrate their effects on the sound quality of the speakers that they support.

The tasks that were completed include:

Planning the Final Stand Build: After our testing on each of the two prototype stands, our vibrational analysis of the stand points to the single column, 3" PVC structure stand as the more rigid of the two prototypes (see previous posts outlining testing procedures and results). Thus, this structural system will be used for the final stand build. We chose a date for this final build (Saturday afternoon, May 7th), and inventoried the materials that we had left over from our first build to determine a list of materials that we still need to buy in preparation for this activity.

Research on Damping Quality of Various Materials: In preparation for the creation of the isolation system that will sit on the top plate of the stand, research was continued on the qualities of an ideal isolative unit. This led to an investigation into the loss factor, dynamic modulus, and other material and mechanical properties that accompany the various materials that we have purchased as potential components of the final designs. Other sources contained math models and other equations that may be helpful in numerically predicting the performance of these materials as damping agents.

Fusion 360: Blake spent much of his time in the lab modeling the different sheets of materials that may be integrated into the isolation system. We will be able to utilize these to model our isolation systems before we physically construct them.

Similarity App: Gabe continued his research into the features of the Similarity PC app that he has downloaded and that we plan to use to analyze the quality of the music produced by the speakers on top of the stand. We are hopeful that this will provide an objective source of data to support any subjective conclusions that we are able to make.

Sound Recording Analysis Software

Several different programs were downloaded and tested to see whether or not they would yield insight in the difference between the original audio files and the recordings. Audiodiff Maker, Similarity, and others were used. All but the first two were quickly proved useless. Audiodiff Maker made an audio file which was the difference between the two programs, but could not align the start of the song in the files, so that the files could not be accurately analyzed. This left Similarity, which claims to compensate for different start times for the tracks. Similarity, upon first test, yielded questionable results. However, this is our best option, so more tests will be run.

Data Analysis

Over the course of the weekend, we have been hard at work analyzing the raw data gathered in the preliminary testing of last week. Essentially we were out to determine which of the stand structures was the most rigid and stable. To do so, we used the Seismometer 6th iOS application, which recorded vibrations at the bottom of the base. The thought process behind the experiment was that the more rigid stand would effectively transport the vibrational motion from the stand to the base. The least rigid would get lower vibration readings, indicating that the stand absorbs energy, decreasing the quality of sound reproduced. Once the more rigid stand is determined (providing the optimal structural base) an effective isolation system comprised of a combination of foam, rubber, cork , or felt would dissipate the vibrations exuded by the speaker at their origin (the point of contact between the speaker and stand), producing the highest quality sound overall.

The Seismometer app produced its data graphically on the app, but allowed for it to be exported in an Excel file numerically. The file was formatted as seen below:

Where the vibrations have been deconstructed into their x,y, and z axis components. Each of these numbers represent the degree of deviation from the base reading (no vibration). These deviations for each of the axes over a 25 second period of a song were summed to determine the gross amount of deviations. The stand that yielded the highest gross deviations was also the stand that was most effective at transmitting the vibrations from the top plate of the stand to the bottom, a result of a rigidly constructed stand structure.

Our results are as follows:

Stand 1:

Stand 2:

Clearly, our results point to stand 1 being the most rigid stand, and therefore the best choice for the structure of the final stand. We as a group will choose a mutually acceptable date to construct the final stand, which will allow us to move on to the construction and testing of the isolation components, which will be able to be tested subjectively (in a room setting with a group of volunteer listeners) and numerically using both the Seismometer app once again as well as sound analysis applications which have already been downloaded. More information to come about logistics for the final stand build, the thought process behind the isolation system, and the applications that will be used for the final testing.