SR-009 EQ (and mod) Thread

I'd like to open a thread for discussion of SR-009 mods and EQ. In keeping with the idea that all headphones can be improved upon, I'd like to offer up a few starting points. I know there aren't that many Stax aficionados here, but it's worth trying.

By the way, I'm running these on Yggdrasil >> KGSSHV. The Innerfidelity measurements that I reference for Stax are, I believe, from a BHSE, and Tyll has stated that the FR did not change depending on taking them from a BHSE vs. his KGSS variant.


http://i.imgur.com/6xblQHf.png (SR-009 FR; I can't post images directly.)

So here's the 009's FR. We can see immediately that low bass is a bit recessed - but not rolled off. And we can see that low mids are also slightly de-emphasized relative to upper mids. Based on the response of headphones like the HD-600, which are neutral and tonally correct (see - http://www.innerfidelity.com/images/SennheiserHD600.pdf ) or which follow the Olive curve like the Focal Spirit Professional (see - http://www.innerfidelity.com/images/FocalSpiritProfessional.pdf ), we can see how the 009's low mids from 200-800 hz are a bit recessed. Thankfully, they're also nice and smooth and should respond well to EQ.

In subjective terms, the 009s stock tend to sound slightly cold, analytical, and tiring.

I started by running +3 dB at 110 hz, 18dB/octave as a low shelf as well as +3dB, 12dB/oct at 700 hz. I found the 700 hz shelf to be slightly excessive and am now running the bass at +3, low mids at +2. It's actually pretty shocking how much this changes the tonality of the headphones. They're now much closer to the 007's (not as warm, though) and much closer to neutral. (I don't have a pair to compare.) (Here's the 007.1's FR for reference - note that low mids are flat rather than recessed, but then the upper mids are on the dark side of neutral; - http://www.innerfidelity.com/images/StaxSR007.pdf.) My hope is an ideally EQ'ed pair of 009's should retain the air and insane clarity and microdetail of the 009's but have more neutral tonality.

Here's the curve, for which I'm using the excellent Pro-Q 2 in linear phase mode:

http://i.imgur.com/yi3bdL8.png

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In terms of modding, I'm planning on experimenting with adding a bit of foam between the rear pad and the headphone to elevate the driver off of my ear. Foam is incoming.

 

@anetode - any thoughts?

 

Thanks.

I'm basically at the same settings for the bass range, just with shelving rather than bell. I'll experiment more with subtracting from 1k. (Looks like 2-3 dB, q=1.5 at 1100hz would work.)