CABLE CONNECTIONS

plugs into Headphone OUT and Mic IN for the Calibration Loop.

Alternatively, you can place the Phantom

Power Supply into the chain by using Two of

these cables.

MIC In jack. The other end, also terminated with a

3.5 mm Stereo TRS plug goes into the Phantom

Power Supply's Line OUT jack. Beneath my Mac's

Mic IN jack with the white cable, you see an optical

cable plugged into my Mac's H

eadphone Out jack.

The other end connects to my Dacmini's Optical IN.

The headphone undergoing measurement is

connected to my Dacmini's headphone jack.







I encourage everyone to consider building and using a measurement kit. I find it indispensable for L-R Channel balancing and tuning. It's also interesting, easy to use, fast (6 seconds per measurement), and fun.





MAKING INCREMENTAL MEASUREMENTS



I mounted the mic in an Etymotic triflange ear tip using hot glue. Next, I applied a ring of hot glue around the mic sitting on its perch at the IEM insertion hole. When making these measurements over two consecutive weekends, I made sure to use the same methodology. I placed the mic in my ear at the same angle and depth on both measurement days. I did not remove the mic until all measurements were completed, each day. I SPL-matched the sweep level for each measurement. Various pads X mod(s) result in wide variability in sensitivity. Matching the sweep levels may not be necessary but I did so to control this variable.



I placed the headphones on my head based on my usual, most comfortable position whenever I use headphones. Considering the number of measurements and variables assessed, I made only 1 measurement for each. The baffles were secured to the cups with masking tape to avoid stripping the cup threads from multiple modding cycles done one at a time. I squeezed the baffle to the cup while taping and insured that all gaps and crevices were tightly sealed. Consider the data FWIW or a "snapshot" of each mod.



The small, sharp up/down "tics" in the SPL FR graphs and the very thin ridges in most of the waterfall plots are the result of "cable noise" from electromagnetic interference according to the REW Moderator.



The FR graphs don't tell us anything about the speed or decay of each mod. I included Waterfall Plots to show the speed and decay on the 'z' axis, back to front.



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/



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 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 an offset value in the offset window - I typically use -155, 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.



***Select 'Room Equalization Wizard (REW) Set-up Guide' (below) for a Google Doc that explains more about how to setup and use REW. I included some useful links and screen shots for clarity.***





You Can Learn How to Use REW Before You Begin Making Your Own Measurements







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. The individual data files are listed on the left side of the measurement window. Delete each file you want to remove by clicking the 'red X' to the right of one. This removes the file(s) from the list but does not permanently delete the file(s) stored in 'Downloads.'



Next, click 'All SPL', located at the top tool bar of the measurement window, to display your chosen graphs as an overlay. You can change the resolution by clicking the '-' or '+' tabs at the top left of the SPL graph; i.e. 5 db or 10 dB SPL intervals. You can save this specific group of graphs by clicking 'Save All' at the top left of the window and type in a Group Name. When you're done comparing this set of measurements, close this file, after naming and saving it, by clicking the 'Remove All' tab. 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 from any of the .mdat files I uploaded to Google Docs.





Incremental Mods and Measurements, REW .mdat files, ARTA Setup Guuide, and Videos stored in Google Docs:



1. Room Equalization Wizard (REW) Set-up Guide



. Main data set 1 .mdat data files for Incremental Mods and Measurements



. Main data set 2 .mdat data files for Incremental Mods and Measurements



4. DBV #1 and #2 .mdat files:

https://docs.google.com/open?id=0B5ZWXtWdNv9UYTBUZHRFTXZZSzQ



5. Stock T50RP, T40RP mk2, T20RP mk2 measurements with Etymotic Foam and Triflange mounted microphones .mdat files:

https://docs.google.com/open?id=0B5ZWXtWdNv9URmRSLW5mN0Vzblk



6. DBV #2 with Taped on FA-003 Pads, T50RP Pads, and Inner Tube Modded FA-003 Pads .mdat files:

https://docs.google.com/open?id=0B5ZWXtWdNv9UWlcyeXVFbU1XblE



7. Disassembling Fostex T50RP/T40RP mkII/T20RP mkII For Repairs and Driver Modification - If this video does not open, try Right Clicking on the File Name and 'Open With Google Drive Viewer.' Also available via dropbox



8. "Radical Russian Roulette" Driver Modification [size=small] Video - If this video does not open, try Right Clicking on the File Name and 'Open With Google Drive Viewer.' [size=small] Also available via dropbox



9. ARTA Setup Guide for Beginners uploaded to Google Drive January 2015





T50RP Incremental Mods and Measurements



Audio Measurement Chain



Calibrated MacBook Pro Soundcard > REW Generated Sweep > Glass Toslink > Dacmini with 1 Ohm Output Impedance Mod > Headphones > Calibrated Panasonic WM-61A Microphone > Calibrated Phantom Power Supply > MacBook Pro > REW Analysis





General Interpretive Guidelines for REW Measurement Graphs



1. Frequency Response Graph (FR): Zero dB horizontal x-axis is the baseline. The frequencies in Hertz (Hz) are shown at the bottom in logrithmic format. The vertical y-axis is Sound Pressure Level (SPL) in decibels (dB) which indicates how "loud" the headphones measure. Positive numbers indicate louder than baseline. Negative numbers indicate less loudness than baseline.



+/- 2 dB above or below the baseline is acceptable and you probably would not be able to hear a significant difference. An ideal FR "curve" would actually be a flat line at zero dB extending all the way across the graph from sub-bass on the far Left to high treble on the far Right.



FR graphs tell us nothing about resonances or ringing, speed of decay, impulse response, phase, or how the headphones will sound. You don't need to worry about any of these for now. Just understand that resonances, ringing, and slow decay speed are "Bad".... and, flat FR and fast decay are "Good."



2. Waterfall Graph: This is a 3D graph with 3 axes - SPL in dB on the vertical y-axis, Frequencies in Hz on the horizontal x-axis, and Decay Time on the Back to Front z-axis. Ideally, you want the x-axis to be as flat and uniform as possible across the top from left to right which indicates an even, or "flat" FR. The waterfall from the back of the z-axis extends forward and indicates the decay speed and whether or not there is ringing at particular frequencies. Generally, you're more likely to perceive a spike than a dip. A "suckout" is a wider (x-axis) range of frequencies that is more easily "heard."



3. Spectrogram: This graph shows speed of decay, ringing/resonances, dips, spikes, and suckouts. The vertical y-axis indicates speed of decay in milliseconds and the horizontal x-axis marks frequencies from sub-bass to treble (Left to Right). The Color Scale on the right side of the graph indicates SPL from 0 = Red to - 40 = Blue. Ideally, you want to see a wide, uniform beam of red with thin layers of yellow, green, and blue from far Left to far Right. Green and Blue "Flames" indicate low level ringing that may be difficult to hear. Yellow and Red Flames are more likely heard. Upward "Bulges" indicate humps. "Squeezed" areas indicate dips. "Pinched off" areas are suck-outs that are more easily heard.



Use all three graphs to better understand your headphones' performance and make more accurate predictions about how they might sound. Start by looking at the "All Stock T50RP" FR and Waterfall graphs. Notice the big hump in the middle and the slopes to either side, especially on the left side. This indicates a mid-centric headphone with weak bass and weak treble that "rolls off." What the graphs do not show, however, is the resonance and standing waves heard from Stock T50RP's and described throughout the main T50RP mod forum.







Begin Incremental Mods and Measurements





A.





Fostex T50RP - All Stock Left Side: Current production with smooth finished metal hangers and non-textured, translucent white driver dampener



1.





All Stock T50RP





2.





Stock with sealed cup vents





3.





Stock with sealed baffle port





4.





Stock with sealed cup vents and sealed baffle port







B.





Masking tape temporarily seals baffle to cup without risking stripping the cup threads. Shure 840 pads (Left) and FA-003 pads (Right-micmacmo's inner tube mod).





5.





Stock with Shure 840 pads





6.





Stock with Shure 840 pads and sealed cup vents





7.





Stock with Shure 840 pads, sealed cup vents, and sealed baffle port





8.





Stock with Shure 840 pads and sealed baffle port





C.























9.





Stock with Shure 840 pads and 3 mm bass port





Grodan rock wool: 10x 60x70 mm with extra "fluff" around the rim. Thanks, JoelPearce and micmacmo.



10.





Stock with Grodan Rock Wool and Shure 840 Pads





11.





Stock with Grodan Rock Wool and Stock Pads





12.





Stock with Grodan Rock Wool and FA-003 Pads



Note: micmacmo's Inner Tube Modded FA-003 Pads were used throughout these measurements.





E.









13.





Stock with Cotton and Shure 840 Pads





14.





Stock with Cotton and Stock Pads





15.





Stock with Cotton and FA-003 Pads





F.





50x60x70 mm Johns Manville fiberglass - uncompressed



G.





50x60x70 mm Johns Manville fiberglass compressed into cup with extra "fluff" around the rim. Note the rubber shock absorber caps showing through the fiberglass.



16.





Stock with Fiberglass and Shure 840 Pads





17.





Stock with Fiberglass and Stock Pads





18.





Stock with Fiberglass and FA-003 Pads





H.





1.5x35x35 mm Creatology Stiffened Craft Felt from Michaels' secured with strips of Transpore tape.







19.





Stock with 1.5x35x35 mm Stiffened Craft Felt over the driver and Shure 840 Pads





20.





Stock with 1.5x35x35 mm Stiffened Craft Felt over the driver and Stock Pads





21.





Stock with 1.5x35x35 mm Stiffened Craft Felt over driver and FA-003 Pads





I.





12x35x35 mm open cell foam over the driver secured with Transpore tape.



22.





Stock with Open Cell Foam over driver and Shure 840 Pads





23.





Stock with Open Cell Foam over driver and Stock Pads





24.





Stock with Open Cell Foam over driver and FA-003 Pads





J.





4x35x35 mm 100% Wool Felt from Hobby Lobby, over the driver



25.





Stock with 4x35x35 mm Hobby Lobby 100% Wool Felt over driver and Shure 840 Pads





26.





Stock with 4x35x35 mm Hobby Lobby 100% Wool Felt over driver and Stock Pads





27.





Stock with 4x35x35 mm Hobby Lobby 100% Wool Felt over driver and FA-003 Pads





K.











28.





Stock with Acoustipack Lite and Felt in Cup Floors with Shure 840 Pads





29.





Stock with Acoustipack Lite and Felt in Cup Floors with Stock Pads





30.





Stock with Acoustipack Lite and Felt in Cup Floors with FA-003 Pads





L1.











31.





Stock with Acoustipack Lite and Felt in Cup Floor, Newplast, and Shure 840 Pads





32.





Stock with Acoustipack Lite and Felt in Cup Floor, Newplast, and Stock Pads





33a.





Stock with Acoustipack Lite and Felt in Cup Floor, Newplast, and FA-003 Pads





L2. This "Naked Driver" is associated with Graphs 33b, 33c, and 33d, Only. ALL preceding and subsequent graphs are based on modifications with the stock white driver dampening paper intact.











33b.





Naked Driver, Acoustipack Lite and Felt in Cup Floor, Newplast, Shure 840 Pads





33c.





Naked Driver, Acoustipack Lite and Felt in Cup Floor, Newplast, and Stock Pads





33d.





Naked Driver, Acoustipack Lite and Felt in Cup Floor, Newplast, FA-003 Pads





M.





1.5x35x35 mm Creatology Stiffened Craft Felt has been added to the back of the driver, directly over the stock white driver dampening paper.



34.





Stock with Acoustipack Lite and Felt in Cup Floors, Newplast, Stiffened Craft Felt over the driver, and Shure 840 Pads





35.





Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, and Stock Pads





36.





Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, and FA-003 Pads





N.











37.





Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton, and Shure 840 Pads





38.





Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton, and Stock Pads





39.





Stock with Acoustipack LIte and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton, and FA-003 Pads





O.









40.





Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, and Shure 840 Pads





41.





Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, and Stock Pads





42.





Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, and FA-003 Pads





43.





Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, Baffle Port Closed, and Shure 840 Pads





44.





Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, Baffle Port Closed, and Stock Pads





45.





Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, Baffle Port Closed, and FA-003 Pads





46.





This is the same FR Graph as the one just above but with 1/24 Smoothing. This is the only FR Graph in this measurement database with any Smoothing applied.







Additional Requested Pictures and Graphs



1. BMF DBV #1: With Shure 840 pads compared with Stock and FA-003 pads

2. My LCD2





P.





















DBV 1



47.







48.







49.





Above: BMF DBV #1 with Shure 840 Pads - SPL FR Graph, Waterfall Plot, and Spectrogram

























know if removing the shock absorbers improves the sound quality but it is possible because the cotton/fiberglass lays flatter and it's more uniformly distributed than when the shock absorbers remain in place. Removing the shock absorbers is not irreversible because they can be super glued back in place.



DBV #1 with T50RP Pads











51.







52.





Above: DBV #1 with T50RP Pads - SPL FR Graph, Waterfall Plot, and Spectrogram







DBV #1 with FA-003 Pads



53.







54.







55.





Above: DBV #1 with FA-003 Pads - SPL FR Graph, Waterfall Plot, and Spectrogram





DBV 2





56.





DBV #2 Left with Shure 840 Pads Compared to All Stock T50RP Left





57.





DBV #2 Left with Shure 840 Pads Compared to All Stock T50RP Left.





58.





DBV #2 Left with Shure 840 Pads compared to All Stock T50RP Left.





59.





DBV #2 Right with Shure 840 Pads compared to All Stock T50RP Right.





60.





DBV #2 Right with Shure 840 Pads compared to All Stock T50RP.





61.





DBV #2 Right with Shure 840 compared to All Stock T50RP Right.





62.





DBV #2 Left with Stock Pads SPL FR





63.





DBV #2 Left Stock Pads Waterfall Plot





64.





DBV #2 Left Stock Pads Spectrogram





65.





DBV #2 Right with Stock Pads SPL FR





66.





DBV #2 Right with Stock Pads Waterfall Plot





67.





DBV #2 Right with Stock Pads Spectrogram





68.





DBV #2 Left with Inner Tube Modded FA-003 Pads SPL FR





69.





DBV #2 Left with Inner Tube Modded FA-003 Pads Waterfall Plot





70.





DBV #2 Left with Inner Tube Modded FA-003 Pads Spectrogram





71.





DBV #2 Right with Inner Tube Modded FA-003 Pads SPL FR





72.





DBV #2 Right with Inner Tube Modded FA-003 Pads Waterfall Plot





73.





DBV #2 Right with Inner Tube Modded FA-003 Pads Spectrogram





74.





DBV #2 Left with Taped on FA-003 Pads SPL FR





75.





DBV #2 Left with Taped on FA-003 Pads Waterfall Plot





76.





DBV #2 Left with Taped on FA-003 Pads Spectrogram





77.





DBV #2 Right with Taped on FA-003 Pads SPL FR





78.





DBV #2 Right with Taped on FA-003 Pads Waterfall





79.





DBV #2 Right with Taped on FA-003 Pads Spectrogram





*****End of Incremental Mods and Measurements*****





My LCD2 Measurements



Triflange and Foam Tip Mounted Mic Comparisons



80.





LCD2 v.1 Left: Triflange Mic compared with Foam Mic





81.





LCD2 v.1 Left: Triflange Mic compared with Foam Mic





82.





LCD2 v.1 Left: Triflange Mic compared with Foam Mic





83.





Audeze's SPL FR Graph of my LCD2 v.1







All Stock T50RP T40RP T20RP Measurements with Triflange and Foam Tip Mounted Mics



Stock T50RP - Triflange and Foam Tip Mounted Measurement Comparisons



84.





T50RP Left: with Triflange Mic compared with Foam Mic





85.





T50RP Left: Triflange Mic compared with Foam MIc





86.





T50RP Left: Triflange Mic compared with Foam Mic





87.





T50RP Right: Triflange Mic compared with Foam Mic





88.





T50RP Right: Triflange Mic compared with Foam Mic





89.





T50RP Right: Triflange Mic compared with Foam Mic







Stock T40RP compared to Stock T20RP with Foam Tip Mounted Mic



90.





T40RP Left compared to T20RP Left using Foam Mic





91.





T40RP Left compared to T20RP Left using Foam Mic





92.





T40RP Left compared to T20RP Left using Foam Mic





93.





T40RP Right compared to T20RP Right using Foam Mic





94.





T40RP Right compared to T20RP Right using Foam Mic





95.





T40RP Right compared to T20RP Right using Foam Mic







About Measurements and Tuning

























Consider and compare these measurements relative to one another. Do not directly compare these measurements with someone else's measurements. There are no "slam dunks." Tweaking, or tuning, is key. You must take anyone's mod and "make it your own." Remember that FR graphs provide only an idea of how a mod may sound relative to another mod configuration. You cannot rely on others' opinions and you cannot know how a mod configuration will sound until you build, tune, and test for yourself. A mod's perceived SQ may be better, or worse, than suggested by its FR graph. This may result from an interaction of variables including your equipment and audio chain, source and file type, your personal SQ preferences, your hearing acuity and psychoacoustic factors such as Placebo Effect, Selective Perception Bias, Expectation Bias (positive and negative), Confirmatory Bias, the ephemeral nature of auditory memory, and Cognitive Dissonance. Consider the graphs, select the various components you want to try, and build your mod. Here is where the real work begins --> tweaking, tuning, and testing one component change at a time to improve and "dial in" the sound you want. You can tweak: cotton thickness, fiberglass thickness if used, bass port size vs stock, modified baffle port size vs stock, Grodan Rock Wool thickness if used, pads used, Dynamat or FatMat vs without, additional acoustic foam in the cup and/or on the ear side of the driver, cotton vs fiberglass vs felt of different types and layers over the ear side of the drivers, omitting any of these components, and adding anything else you're interested in trying. You can literally tune for bass, midrange, or treble emphasis or go for neutral which is what I try to achieve. Be aware that changing one component will likely effect others in your design. Based on my experiments, "the total (SQ) is greater than the sum of its parts." Note: All DIY measurements were made with the same methodology and measurement chain using a Triflange Mic unless stated otherwise below each graph. 50.51.52.Above: DBV #1 with T50RP Pads - SPL FR Graph, Waterfall Plot, and Spectrogram53.54.55.Above: DBV #1 with FA-003 Pads - SPL FR Graph, Waterfall Plot, and Spectrogram56.DBV #2 Left with Shure 840 Pads Compared to All Stock T50RP Left57.DBV #2 Left with Shure 840 Pads Compared to All Stock T50RP Left.58.DBV #2 Left with Shure 840 Pads compared to All Stock T50RP Left.59.DBV #2 Right with Shure 840 Pads compared to All Stock T50RP Right.60.DBV #2 Right with Shure 840 Pads compared to All Stock T50RP.61.DBV #2 Right with Shure 840 compared to All Stock T50RP Right.62.DBV #2 Left with Stock Pads SPL FR63.DBV #2 Left Stock Pads Waterfall Plot64.DBV #2 Left Stock Pads Spectrogram65.DBV #2 Right with Stock Pads SPL FR66.DBV #2 Right with Stock Pads Waterfall Plot67.DBV #2 Right with Stock Pads Spectrogram68.DBV #2 Left with Inner Tube Modded FA-003 Pads SPL FR69.DBV #2 Left with Inner Tube Modded FA-003 Pads Waterfall Plot70.DBV #2 Left with Inner Tube Modded FA-003 Pads Spectrogram71.DBV #2 Right with Inner Tube Modded FA-003 Pads SPL FR72.DBV #2 Right with Inner Tube Modded FA-003 Pads Waterfall Plot73.DBV #2 Right with Inner Tube Modded FA-003 Pads Spectrogram74.DBV #2 Left with Taped on FA-003 Pads SPL FR75.DBV #2 Left with Taped on FA-003 Pads Waterfall Plot76.DBV #2 Left with Taped on FA-003 Pads Spectrogram77.DBV #2 Right with Taped on FA-003 Pads SPL FR78.DBV #2 Right with Taped on FA-003 Pads Waterfall79.DBV #2 Right with Taped on FA-003 Pads SpectrogramTriflange and Foam Tip Mounted Mic Comparisons80.LCD2 v.1 Left: Triflange Mic compared with Foam Mic81.LCD2 v.1 Left: Triflange Mic compared with Foam Mic82.LCD2 v.1 Left: Triflange Mic compared with Foam Mic83.Audeze's SPL FR Graph of my LCD2 v.184.T50RP Left: with Triflange Mic compared with Foam Mic85.T50RP Left: Triflange Mic compared with Foam MIc86.T50RP Left: Triflange Mic compared with Foam Mic87.T50RP Right: Triflange Mic compared with Foam Mic88.T50RP Right: Triflange Mic compared with Foam Mic89.T50RP Right: Triflange Mic compared with Foam Mic90.T40RP Left compared to T20RP Left using Foam Mic91.T40RP Left compared to T20RP Left using Foam Mic92.T40RP Left compared to T20RP Left using Foam Mic93.T40RP Right compared to T20RP Right using Foam Mic94.T40RP Right compared to T20RP Right using Foam Mic95.T40RP Right compared to T20RP Right using Foam Mic I used a Dremel cutting tool to remove all 4 shock absorber posts inside each cup. This makes it easier to place the cotton and fiberglass overlay. I don'tif removing the shock absorbers improves the sound quality but it is possible because the cotton/fiberglass lays flatter and it's more uniformly distributed than when the shock absorbers remain in place. Removing the shock absorbers is notirreversible because they can be super glued back in place. Note, also, that I typed in the wrong dimensions for the bass ports in the Notes section of these graphs. Instead of 2x2 mm bass ports for these DBV measurements, the actual bass ports are 3mm wide and ~1 mm high - and placed over the center of the lowest of the 4 cup vents. 4. Shure 840 pads 3. Dynamat (or FatMat) with self-adhesive felt overlay around the ear side of the drivers 2. Baffle ports are sealed with GE Silicone II 1. 3x1 mm bass ports over the black cup vent felt on the inside of the cups Note: I inadvertently failed to list four important mod components in the Notes Section of my DBV graphs, above: The "DBV" designation in the Notes section of these graphs is simply my way of keeping track of various mods I'm working on. This mod configuration is a variation of BMF V8.1 described with pictures in "The Fostex T50RP Mods Summary Links" WIKI started by Ardilla. This mod is fast and neutral with excellent bass extension, texture, and definition. Mids are properly placed, clear, and lush, particularly for vocals and acoustic music. Treble extension, detail, and shimmer are very good without fatigue. Imaging is precise, channel balance is perfect, and soundstage is wide for a closed 'phone. DBV#1 Left Cup: 20x60x70 mm (measured Uncompressed) Rite Aid Natural Absorbent Cotton with 10x60x70 mm (measured Compressed) Fiberglass overlaying Acoustipack Lite and Paxmate "Ladder Rungs." Baffle: Newplast Flush Mass Loaded baffle compartments, stiffened felt over stock white driver dampener and Transpore overlay. Note: Acid-free double sided tape applied to the driver grid perimeter works better than Transpore for securing the stiffened felt.47.48.49.Above: BMF DBV #1 with Shure 840 Pads - SPL FR Graph, Waterfall Plot, and Spectrogram Q. DBV #1 and #2 Left Cup: 3x15 mm Paxmate "Ladder Rungs" over Acoustipack Lite in floor wells. 1.5x35x35 mm Creatology Stiffened Craft Felt over stock white driver dampener, Transpore overlay, and Newplast Flush Mass Loaded Baffle Compartments. Double Sided tape works best for securing stiff felt to the driver back for the permanent mod. For DBV #2, cut 10x60x70 mm fiberglass, similarly notched for the shock absorbers, and place over 20x60x70 mm cotton. You may need more/less of each for your mod, determined by tuning40.Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, and Shure 840 Pads41.Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, and Stock Pads42.Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, and FA-003 Pads43.Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, Baffle Port Closed, and Shure 840 Pads44.Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, Baffle Port Closed, and Stock Pads45.Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton over Fiberglass, Baffle Port Closed, and FA-003 Pads46.This is the same FR Graph as the one just above but with 1/24 Smoothing. This is the only FR Graph in this measurement database with any Smoothing applied.P. 25x60x70 mm cotton has been notched to fit around the shock absorbers and jack, placed over Acoustipack Lite in cup. Cutting off the shock absorbers is not required. Removing the rubber shock absorber caps gives you a bit more room to work but this is also optional. If you remove them, save them in case you want to go back to stock.37.Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton, and Shure 840 Pads38.Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton, and Stock Pads39.Stock with Acoustipack LIte and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, Cotton, and FA-003 PadsO. "Naked" Driver has had its stock white 'paper' removed, Acoustipack Lite and Felt in Cup Floors, and Newplast Flush Mass Loaded in the baffles. I do not recommend removing the stock white driver dampening "paper" from the back of the drivers. In my experience, this offers no benefits over keeping the stock white dampener intact.33b.Naked Driver, Acoustipack Lite and Felt in Cup Floor, Newplast, Shure 840 Pads33c.Naked Driver, Acoustipack Lite and Felt in Cup Floor, Newplast, and Stock Pads33d.Naked Driver, Acoustipack Lite and Felt in Cup Floor, Newplast, FA-003 PadsM.1.5x35x35 mm Creatology Stiffened Craft Felt has been added to the back of the driver, directly over the stock white driver dampening paper.34.Stock with Acoustipack Lite and Felt in Cup Floors, Newplast, Stiffened Craft Felt over the driver, and Shure 840 Pads35.Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, and Stock Pads36.Stock with Acoustipack Lite and Felt in the Cup Floors, Newplast, Stiffened Craft Felt over the driver, and FA-003 PadsN. 31.Stock with Acoustipack Lite and Felt in Cup Floor, Newplast, and Shure 840 Pads32.Stock with Acoustipack Lite and Felt in Cup Floor, Newplast, and Stock Pads33a.Stock with Acoustipack Lite and Felt in Cup Floor, Newplast, and FA-003 PadsL2. This "Naked Driver" is associated with Graphs 33b, 33c, and 33d, Only. ALL preceding and subsequent graphs are based on modifications with the stock white driver dampening paper intact. 20 grams of Newplast is less than 1 oz. 10 grams per side. Acoustipack Lite and self-adhesive felt in the cup. Newplast "Flush Mass Loaded" in the baffle compartments. A digital scale is not required. I used one to demonstrate just how little Newplast or plasticine is needed Acoustipack Lite and Self-Adhesive Felt in the cup floor. The Acoustipack is in the left and right "floor wells" and the self-adhesive felt is at the top and bottom of the center area, above and below the headband hanger compartment.28.Stock with Acoustipack Lite and Felt in Cup Floors with Shure 840 Pads29.Stock with Acoustipack Lite and Felt in Cup Floors with Stock Pads30.Stock with Acoustipack Lite and Felt in Cup Floors with FA-003 PadsL1. A better method uses 1.5x37x45 mm Creatology Stiffened Craft Felt secured by double sided tape strips cut to fit the outer edges of the driver grid. Thanks nick n.19.Stock with 1.5x35x35 mm Stiffened Craft Felt over the driver and Shure 840 Pads20.Stock with 1.5x35x35 mm Stiffened Craft Felt over the driver and Stock Pads21.Stock with 1.5x35x35 mm Stiffened Craft Felt over driver and FA-003 PadsI.12x35x35 mm open cell foam over the driver secured with Transpore tape.22.Stock with Open Cell Foam over driver and Shure 840 Pads23.Stock with Open Cell Foam over driver and Stock Pads24.Stock with Open Cell Foam over driver and FA-003 PadsJ.4x35x35 mm 100% Wool Felt from Hobby Lobby, over the driver25.Stock with 4x35x35 mm Hobby Lobby 100% Wool Felt over driver and Shure 840 Pads26.Stock with 4x35x35 mm Hobby Lobby 100% Wool Felt over driver and Stock Pads27.Stock with 4x35x35 mm Hobby Lobby 100% Wool Felt over driver and FA-003 PadsK. "Unobtanium" Rite Aid Natural Absorbent Cotton - approximately 15 cm wide and 4 cm thick out of the box and easily separated to the desired thickness. Other types of cotton may work but will likely require altering the amount and thickness used.13.Stock with Cotton and Shure 840 Pads14.Stock with Cotton and Stock Pads15.Stock with Cotton and FA-003 PadsF.50x60x70 mm Johns Manville fiberglass - uncompressedG.50x60x70 mm Johns Manville fiberglass compressed into cup with extra "fluff" around the rim. Note the rubber shock absorber caps showing through the fiberglass.16.Stock with Fiberglass and Shure 840 Pads17.Stock with Fiberglass and Stock Pads18.Stock with Fiberglass and FA-003 PadsH.1.5x35x35 mm Creatology Stiffened Craft Felt from Michaels' secured with strips of Transpore tape. D.9.Stock with Shure 840 pads and 3 mm bass portGrodan rock wool: 10x 60x70 mm with extra "fluff" around the rim. Thanks, JoelPearce and micmacmo.10.Stock with Grodan Rock Wool and Shure 840 Pads11.Stock with Grodan Rock Wool and Stock Pads12.Stock with Grodan Rock Wool and FA-003 PadsNote: micmacmo's Inner Tube Modded FA-003 Pads were used throughout these measurements.E. When you have determined the size of the bass port needed for your mod configuration, you can make a permanent one by duplicating and placing it over the cup vents on the inside. Cut a piece of masking tape to cover all the stock black cup felt overlaying the cup vents. Place the tape over the vent felt on the inside of the cup. Use shirt pins pushed through from the outside to mark the limits of the bass port width on the inside. Use the "pin markers" to trace a rectangular opening on the masking tape. Remove the tape but leave the pins in place. Cut out the rectangle from the masking tape, re-apply the tape onto the vent felt on the inside by using the pins as your guide, and remove the pins. Glue all the way around the masking tape so it will remain in place and not "leak" around the edges. The size of your bass ports from left to right may need to be different to balance the FR. In some cases, you may have, for example, a 3x1 mm bass port on one side and no bass port on the other side. Temporary Bass Port using electrical tape or masking tape on the outside of the cup vents. Once the mod is completed, the bass port is moved to the inside of the cup unless you prefer the flexibility of re-tuning, on the fly. Masking tape makes the job easier because you first apply a piece that covers all 4 cup vents and then use an X-acto knife to cut the precise size bass port you want. This masking tape bass port is 3x1 mm. To prevent the tape from separating at the corners (Not Shown in the photo, above), use an X-acto knife to remove the excess tape from where it overlaps onto the back of the cups and down the side walls flush with the cup vents. Once removed, smooth out and compress the tape flat onto the four cup vent slots. Use an X-acto knife to cut an opening over the center of one of the vent slots to make your modified bass port. Enlarge by 1 mm increments. If it's too wide, bass bloat will return. In this case, decrease the width of the bass port in 1 mm increments by placing a small piece of masking tape over part of the bass port already opened. A.Fostex T50RP - All Stock Left Side: Current production with smooth finished metal hangers and non-textured, translucent white driver dampener1.All Stock T50RP2.Stock with sealed cup vents3.Stock with sealed baffle port4.Stock with sealed cup vents and sealed baffle portB.Masking tape temporarily seals baffle to cup without risking stripping the cup threads. Shure 840 pads (Left) and FA-003 pads (Right-micmacmo's inner tube mod).5.Stock with Shure 840 pads6.Stock with Shure 840 pads and sealed cup vents7.Stock with Shure 840 pads, sealed cup vents, and sealed baffle port8.Stock with Shure 840 pads and sealed baffle portC. [size=small][/size] [size=x-small][/size] [size=small] [/size] [/size] [size=small].[/size] I uploaded the REW raw data .mdat files to Google Docs for all incremental measurements I made and listed in the links, below. 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 the desired set of .mdat files, and the data files will load into REW. Be patient. We're almost there...

Magnification is necessary to make sure there are no shorts when making the mic and TRS connections. A single stray strand of wire can short at the mic and at the TRS.Blue 3.5mm male Stereo TRS to 3.5mm male StereoWhite 3.5mm Stereo TRS cable plugs into my Mac'sThese two photos show the rest of the connections:White cable from Mac Line IN to Phantom Power Supply Line OUT.Mic mounted on Etymotic triflange IEM ear tip terminated with a Female RCA plug connects to either of two Male RCA plugs.Dual Male RCA Y-Splitter to 3.5 mm Stereo TRS plug goes in the Phantom Power Supply's Line IN.Place the mic in your ear and be sure you position it the same way each time you measure = Same depth, Same angle, Same ear.Place the headphones on your head and make sure you use your normal position and with same clamping force each time.Use an earplug in your non-measuring ear to protect your hearing.Turn down the volume, Select 'Measure' and then Select 'Check Levels.' Increase volume until you reach 'Check Level' = -20 dBSelect 'Cancel'Select 'Measure' and Select 'Start Measuring'See Link to Tutorials with Screen Shots (Just Below) for details about configuring, calibrating, and setting-up and using REW. There are more photos of making your microphone near the bottom of this very long post.