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Author Topic: STAX SR-009 Frequency Response  (Read 14620 times)

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ultrabike

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Re: STAX SR-009 Frequency Response
« Reply #20 on: November 09, 2013, 08:22:25 AM »

N3rdling came through and provided his SR-009, modded SRM-727 and SRM-T1!

Awesomeness Milos!!!  :money: :money: :money:

This time around, cans were measured as I usually do closed cup designs that require seal. I believe Arnaud discussed the need for this with electrostats here.  Marv pointed out that the electrostats might have certain resonance issues. Seems the free air resonance of the diaphragm might be 100 Hz from Arnaud's discussion, which may explain the roll off I was getting at that frequency when measuring with sound absorbing, but leaky foam coupling around the pads (not exactly free air tho).

I listened to a few songs with these cans with the SRM-727 and did not hear a 100 or 80 Hz bass roll off. I liked quite a bit what I heard from them. Detail and cleanness is the greatest asset of these cans IMO.

So here are some measurements with the SRM-727:

Frequency Response



Distortion right



Distortion left



CSD right



CSD left



Notes: I'm not certain the notch around 5 and 6 kHz is a headphone or coupling related. It does not show on all closed headphone measurements however. It seems to show up in IF measurements of possibly another 009 set too, though perhaps not as deep.
« Last Edit: November 09, 2013, 08:40:53 AM by ultrabike »
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ultrabike

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Re: STAX SR-009 Frequency Response
« Reply #21 on: November 09, 2013, 08:27:24 AM »

Measurements with SRM-T1:

Frequency Response:



Distortion Right



Distortion Left



CSD Right



CSD Left

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ultrabike

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Re: STAX SR-009 Frequency Response
« Reply #22 on: November 09, 2013, 08:37:46 AM »

Comparison of channels using modded 727 and T1:

Right channel (727 red, T1 yellow)



Left channel (727 green, T1 blue)

« Last Edit: November 09, 2013, 08:43:39 AM by ultrabike »
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Marvey

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Re: STAX SR-009 Frequency Response
« Reply #23 on: November 09, 2013, 10:28:34 AM »

Ultrabike's latest measurements pretty much gels with how I hear the SR009 with a good seal: Middle-midrange emphasis with a slight downward slope toward the extremes (both treble and bass) with sub-bass rolloff.

Distortion is amazingly low - as we have all suspected.
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shipsupt

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Re: STAX SR-009 Frequency Response
« Reply #24 on: November 09, 2013, 12:03:09 PM »

Marv,
Were your original measurements in this thread done with the T2?
Chris
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Yeah, well, you know, that's just, like, your opinion, man.

jerg

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Re: STAX SR-009 Frequency Response
« Reply #25 on: November 09, 2013, 07:18:33 PM »

Ultrabike's latest measurements pretty much gels with how I hear the SR009 with a good seal: Middle-midrange emphasis with a slight downward slope toward the extremes (both treble and bass) with sub-bass rolloff.

Distortion is amazingly low - as we have all suspected.

Hm, but how does it retain a lot of airiness despite the upper treble roll-off? I recall you mentioned something about extended linear upper treble (10-20kHz) behaviour as almost a prerequisite for airiness.
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ultrabike

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Re: STAX SR-009 Frequency Response
« Reply #26 on: November 09, 2013, 08:35:48 PM »

I agree with Marv. While I felt these retained both airiness and bass response, I also felt they were somewhat deemphasized relative to the mids, which may be characteristic of many electrostats.

IMO, these don't have the airiness and soundstage of an HD800, or the bass response of some of the planars. There might be some mids coloration there. However, they are pretty high fi across the whole spectrum.
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shipsupt

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Re: STAX SR-009 Frequency Response
« Reply #27 on: November 09, 2013, 08:39:54 PM »

IMO, these don't have the airiness and soundstage of an HD800,

I agree, they are never as open or airy as the HD800, but at times I am very impressed with the imaging they can pull of.  The fact that they can pull off the stat disappearing act is different than airiness.

I think of air starting a little further up than 10k, like somewhere well past 12k.
« Last Edit: November 09, 2013, 08:48:28 PM by shipsupt »
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Marvey

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Re: STAX SR-009 Frequency Response
« Reply #28 on: November 09, 2013, 08:53:30 PM »

My original measurements were done with the SRM323, and obviously I did not get as good a seal. (Hence greater rolloff and bass mid-bass bump). My measurement rig and methodology were still a work in progress back then.

As far as the airiness factor, I suspect (haven't gone thru all the data), that UB's treble measurements tend to be a few db lower than mine. Even then, "air", i.e. > 12kHz measurements tend to be untrustworthy and very subject to placement factors. I tend to use my ears for > 12kHz than the measurements... after all, I don't hear the LCD3 as being an especially airy headphone despite a lot of measured energy in the last half octave.
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ultrabike

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Re: STAX SR-009 Frequency Response
« Reply #29 on: November 09, 2013, 09:39:44 PM »

Also, these measurements were done with 44.1 kHz sampling rate. If Milos and I meet again, or if I get a chance, I will measure again using 96 kHz.

As implied by Marv, coupling materials make a difference in the response probably depending on many factors like density, composition, thickness, and so forth.
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