Fostex T50RP Incremental Mods and Measurements - Page 2

Quote:

Originally Posted by Dyaems 

Thanks for your time and pics BMF, although I am wondering some of the images doesn't have "graphs" on it? Just the straight line.

Hi Dyaems,

Initially I uploaded graphs as tiff files. They did not open for me, either, unless I used my iPhone 4S, for some reason I don't understand. I just converted them all to PNG files and re-uploaded all the graphs. They open for me, now. Let me know if you can open them.

Thanks,

BMF

Quote:

Originally Posted by Dyaems 

Yup, all of them are fine now. Thanks!

Great! I'm glad they work, now.

Quote:

Originally Posted by Armaegis 

Wow, practically a thesis worth of material here.  I wonder if it would be possible to present the data in some sort of online database, something akin to Headroom's graph comparison system.

This is an interesting idea but probably not worth the effort since these "snapshot" DIY measurements were made with a measuring kit that cost $50.00. There's No comparison to the professional rigs used by purrin and Tyll that cost $50,000.00.

Quote:

Originally Posted by Indread 

Thanks for the incredible dedication and awesome FR graphs.

 

I noticed the FR graphs are a lot flatter with the Shure pads, over the 003/HM5 pads, despite of many people (maybe a majority) preferring the HM5 pads. Is there something I'm missing?

 

In the very last FR graph for this mod (Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, Baffle Port Close, and FA-003 Pads), there is a peculiar giant plunge off in the treble range at one point. Was this in error, or a symptom of closing the baffle port and using the 003 pads together? This oddity isn't there with the Shures.

There is no significance to the sharp drops with this graph relative to the other graphs, IMO. This measurement plummet is consistent across my mods and my measurements of my LCD2 v.1. I believe this is due to the measurement system crossed with the shape of my pinna.

I included a graph for this config in the OP thread with 1/24th Smoothing. Take a look at all the graphs. You will see similar dips at that point on the FR graph.

I hope this helps.

I spent the past few hours formatting, copying, converting to PNG files, and uploading the waterfall plots associated with each FR graph in a side-by-side display. The waterfall plots show the speed of the decay by frequency in Hz X time in milliseconds. Compare the FR graphs with the waterfall plots for a better understanding of both measurement types.

Quote:

Originally Posted by Armaegis 

 

Times like this make me wish I knew how to program... I can see how the database/queries would work, but have no idea how to implement it. And don't sell yourself short about your measurements not being worth the effort. No one else so far has attacked it as vigorously as you have, and the key thing is that you have approached it in a methodical and consistent manner which makes it very valuable. 

 

If we could somehow build a frontend for the database, if you (or anyone else) ever built up another set of graphs it would be a "simple" matter to simply import that or create another database for use. 

 

Are you able to make overlays of the FR graphs? Such as for each modding arrangement but with the three different pads? Or with the same pads but different mods? 

Anyone can download and use REW for free but please contribute (any amount) to support the site. You can use, view, and manipulate .mdat files without having to actually make any measurements of your own. Here's the link:  http://www.hometheatershack.com/roomeq/

I uploaded the REW raw data (.mdat files) to Google Docs for all incremental measurements I made. You first download and install REW and then download and save the .mdat files from Google Docs into your computer's 'Downloads' file. Next, open REW and click on 'Open', go to your 'Download' files, double click one of the .mdat files, and the data files will load into REW.

The default graph format is SPL FR. Tabs across the top of the measurement window allow you to 'Generate' waterfall plots and spectrograms. You must first adjust the SPL FR display to 'Zero' before Generating waterfalls and spectrograms.  To do this, click the 'gear' icon at the top right of the measurement window, type in -155 in the offset window and then click 'Add to Data.' Go to the left side, vertical slider to pull the adjusted SPL FR graph down into the display window. Now, you can generate waterfalls and spectrograms along with decay and several other options, if interested. 

In the T50RP Mods Summary WIKI started by Ardilla, I have a WIKI entitled "BMF V8.1 Mods". One of the links in this group takes you to a Google Doc that explains more about how to use REW, including screen shots for clarity.

Within REW's measurement window, and after you've 'Opened' a .mdat data file, you can delete all but the particular graphs you want to overlay with one another by clicking the 'red X' you will see on the left side of the measurement window. Next, click 'All SPL', located at the top tool bar of the measurement window, to display your chosen graphs as an overlay. You can also change the resolution by clicking the '-' or '+' tabs at the top left of the SPL graph; i.e. 5 db or 10 dB. You can save this specific group of graphs by clicking 'Save All' at the top left of the window and naming it. When you're done comparing this set of measurements, close this file, after naming and saving it, by clicking the 'Remove All' tab and re-open the complete .mdat file to repeat the process for a different group of comparisons. For example, you can delete all but the 3 graphs for "Stock Left Acoustipack Lite, Newplast, and type of pad (840, Stock, and FA-003 pads) for comparing and overlaying these 3 graphs. Do the same for any other combination of incremental measurements in one or both of the two sets of .mdat files I uploaded to Google Docs.

Here are the links for my Incremental Mods and Measurements REW .mdat files stored in Google Docs:

1 of 2 .mdat data files:  https://docs.google.com/open?id=0B5ZWXtWdNv9UczQtX3lxUW1CWnM

2 of 2 .mdat data files:  https://docs.google.com/open?id=0B5ZWXtWdNv9UblZtWjlISjYxSm8

***I have not yet tested this so let me know if it does not work and I'll troubleshoot it.***

Edit: I just tested the first .mdat data set. It worked and downloaded the files already adjusted at 'Zero' display and 5 dB resolution. You Must first download and install REW.