SAATI Filters: Can They Replace Toilet Paper for Headphone Modifiers?
I sent the SAATI filter book and a few headphones to him so that he could play around with the various filter materials to select a few that we might put together a group buy for headphone modding fans so they wouldn't have to keep resorting to toilet paper and other odd materials. I figure why not use the real stuff. Here's his analysis.
For better or worse, Tyll tasked me with answering perhaps one of the most important questions of this age. Can SAATI Acoustex filters be used in place of toilet paper, a staple product used for front damping in headphone mods? Seeing as the last few months have been insanely busy for me, it took me quite some time to investigate. But…yes, I do think SAATI has a toilet paper replacement on its hands!
I used five different headphones for this experiment, all of differing types and with unique sonic traits. These headphones were the AKG 553, Philips Fidelio L1, Sennheiser HD565, Thinksound On1, and the E-MU Walnut.
If you are not familiar with headphone modding, one easy way to tone down hot treble is to place toilet paper over the driver. This is usually as simple as cutting it to fit directly over the driver and placing pads back on or, most commonly and most useful for rapid testing, cut into a disc to be slipped right under the pads without any disassembly. Yes, the type of toilet paper and number of plies matters, and all I had on hand was some generic, septic-safe, "soft," 1-ply toilet paper. (Testing various brands and types of toilet paper along with SAATI filters would drive me mad, so let's not go there.)
As I touched on above, I cut the toilet paper and SAATI filters into discs and slipped them under the pads from the front side. Easily repeatable, quick, and effective. I then proceeded to measure each headphone in a stock configuration, with the pre-selected variety of SAATI filters, and with the toilet paper disk. I used a sort of in-ear microphone for my measurement tests, and while I won't go into details about that or how my results usually look, the relative differences should still be consistent and valuable.
I used the following SAATI filters in my experiments (B = black, the color of the filters):
|Filter||Specific Airflow Resistance (in MKS rayls)||Pore Size|
I gathered the measurements for all the headphones listed and figured the easiest and most holistic way to view the data would be to get an average view of how the SAATI filters changed the sound of the headphones. This was as simple as averaging the decibel changes among the headphones and all front damping filter configurations.
I've presented this data in nice graphs, albeit these are best viewed as high resolution images. No filter is always a flat 0dB reference. All data points are matched at 1KHz.
The findings turned out to be quite simple, actually. In general, as airflow resistance went up with each filter, the treble response went down. You will see some data points that look very rough or spikes that are even higher than the stock baseline. This is almost always due to the filters and slight measurement variances shifting peaks around ever so slightly. Keep that in mind, as it's better to take a broad look at the results when analyzing the data.
Graph 1 shows filters 003 through 010 had little effect on the sound. Results could very well be attributed to measurement variation.
Graph 2 shows filters 025 through 090 appear to be attenuating the 5-10KHz area by 1-2dB at most but, again, some of this is bound to be standard measurement variance.
Filters 115-260 are where things take an interesting turn. Filters 115 and 160 are very similar and affect the general treble area by about 2-2.5dB or so. The 260 filter knocks some spots down as low as 4-4.5dB. Any other changes to the frequency response below 2KHz or so are still under 1dB.
I found my cheap, 1-ply toilet paper performed most similarly to the 115 or 160 filters on average. My guess is that 2-ply toilet paper will perform similarly to the 260 filter.
Overall, it's pretty clear that the SAATI filters tone down the treble much like toilet paper. Don't get too hung up on differences below that. Any changes in the bass or mids could be filters causing a headphone to act a bit odd in other areas, enough to throw off the average results a bit, or could be something as simple as unit-to-unit variation in the lower registers. Remember, this is a rough average, so you want to take more of a broad look at it all.
Speaking of the filters causing headphones to act a bit odd, I wanted to point out a quick example that emphasizes the fact that sometimes toilet paper or similar front damping materials might not be the best solution. (Side note, in these cases, look into open-cell foams.)
Here you can see just a few select filters and the relative differences they cause on only the E-MU Walnut.
The E-MU Walnut already exhibits a bit of a relative peak around 3KHz (ordinary measurements not shown), and these sort of front damping filters boost that spot in ways that could be unpleasant. The overall level of the bump might still be manageable, but when you're lowering the response right after that, it could stick out in a bad way. This just goes to show that while SAATI filters and toilet paper can be used to attenuate treble on average, neither are necessarily the best solution in every case.
Can SAATI Acoustex filters be used as a front-damping, toilet paper replacement for headphones? I would say so! The materials are certainly nicer looking and less likely to tear or fall apart compared to toilet paper. If we enthusiasts can obtain some, whether that be through a group buy or some other method, I think the 115, 160, and 260 filters should give modders plenty to play with.
Editor's Note: Well, there you have it. SAATI filters B115, B160, and B260 should give enthusiasts a nice range of control for front damping, and will be far more reliable in the long run than toilet paper.
I will be happy to coordinate the purchase of materials from SAATI through my contact there. But I won't have time to organise the group buys themselves. I love to see a long-time modding enthusiast at Head-Fi.org, superbestaudiofriends.org, and/or head-case.org start some group buy threads for these three materials.
All three materials are sold by the yard and are 43" wide. Costs are: B160 $46.31/yard; B260 $46.61/yard. I don't have the price quote for the B115 material yet, but it should come in around $35/yd.
Folks willing to organise group buys should start a thread on their respective forums and then email me a link at firstname.lastname@example.org. Please try to finish taking orders by the end of the year and I'll place the final order from SAATI after I return from CES about January 10. My suggestion would be that each participant would order one of each material, about 21.5" wide (half the width of the source material) by maybe a foot long. Cost for all three pieces should be in the $20 neighborhood. But that's just a suggestion, the folks doing the organizing should make the call based on demand.
Let me know!