purrin

But yes, I've started doing the "dummy head" type tests too. The results with open phones are similar between anechoic an dummy head tests. Closed type phones are different story. See my reply on other site.

Hahaha. 10 different ways of doing the same thing with most of them not working. Sounds like MS.

Nice result. Looks like there's some correlation. Let me know if you need any raw impulse response files of other headphones from me for comparison / tweaking Tyll's settings.

Tyll's data has 512 points sampled at 170kHz. At that frequency, the time increment per sample is 1/170k = 0.0000058. 0.0000058 x 512 samples = ~0.003 or 3ms worth of data for the impulse response. 3ms is only just enough time for a signal of 333Hz to complete it's cycle. Another factor is the nature of transforming the impulse response to a FR - there is much less resolution at lower frequencies than high frequencies. So we may as well start at 500Hz. One major purpose of CSD's is to find resonances or ringing of the driver (which hurts the ears.) Oftentimes ringing is usually seen on on FR graphs as sharp spikes. But sharp spikes in FR do not always indicate ringing. The CSDs can confirm the ringing. Examples of bad ringing are the John Grado CSDs which have these high ridges throughout the midrange and treble. Another purpose of these graphs is to see how fast the driver decays. There is some correlation between decay and perceived speed, clarity, and transparency. I just posted a Koss ESP950 measurement at Head-Fi. You can compare this CSD to those of other headphones which are known to sound like shit (Sony XB700, etc.) These plots are simply tools to confirm observations (and help in the design or modification of headphones, e.g. Fostex modders, etc.), nothing more. Finally, Arnaud and I are still trying to sort out Tyll's data - to see if it's clean or good enough to crank out meaningful measurements. So it's still too early to give you an executive summary at this time.

Arnaud, compare the first 3ms of the impulse response of my HF2 data and Tyll's. It doesn't look like there is a window function to ensure delay, but it does appear there is some high frequency filter function applied after ~1.5ms on Tyll's data. The impulse response starts to look overly smooth with rounded curves. Let me know what you think. The SR009 is finally shipping in the States, so I should be getting mine sooner rather than later.

I got in at the last minute, so I don't mind getting mine last. But on the other hand, I'm eager to get some nice waterfall plots of them. But as you said, the rest are probably coming in sooner than later.

Here are a few more on Tyll's data. Arnaud, can you confirm results? I can't help feel that I've messed up on something - I tend to code really quickly without checking the details. The 512 points would be fine at a lower sampling rate, but at 170kHz, it's just not enough, particularly in the lower midrange. My own HF2 measurements are quite a bit different (they show more ringing). You can see those on HF.

Yup. Didn't look at the sample rate, 170357kHz! Exactly on the 512 samples. Too coarse and also not enough to even get any data beyond 3ms which is only good for ~333 Hz upwards.

Thanks Tyll, Here is quick one of the LCD2r2: Hard to tell if internal cup - dummy head reflections are playing a part. It's important to note my measurement methods are very different. I'm trying to get an LCD2r1 from someone locally. I'll run the data through with different parameters (-40db scale) at a later time tonight to filter some crap like the 20+ kHz node which appears to be a measurement artifact. Also, I get the feeling the amplitude in Tyll's data is not pressure in Pa. but db. I've got to re-code to account for this and run the data through again (Yup - just confirmed it - what you now see above is good.) THIS IS STILL NOT RIGHT - MY FR SCALE IS OFF! ASSUMING A WRONG SAMPLE RATE. TIME SCALE IS OFF TOO. I'll let Arnaud run the rest until I back which will be late tonight PST. Arnaud, I think this is good. Took me a while, but this is what I get for hard-coding everything and not documenting my code. Can you confirm with your own analysis?

My concern is that the reflections from the headphone cups and dummy would be too early and have an adverse effect (causing cancellation or excitation nodes on the measurements. (The ear/brain has an amazingly funny way of being able to filter crap like this.) The room reflections in the data I gave Arnaud were 7-9 ms away - one and half meter, so those could easily be gated away - chop off everything after 5-6ms. In any case, as we saw, even if we included the reflection, the effect was so miniscule that it had no effect on the CSD plot. Ideally, the best way would be mount one cup or driver on a large baffle and take the measurement in an anecolic (or close to it) chamber. Tyll, I'd be game if you want to send me some data as well. My graphs are prettier too. Anyways I would be curious on the effect of the dummy head vs. my primitive low-tech, but apparently effective means of measurement. The more data, the better, especially if using differing measurement methods.

Yup, that's all you need - the impulse response. I don't know how funky the data might be because of the effects of the headphone cups and dummy head, but it's worth a shot (You may need another measurement method since the purpose of the CSD is different from the FR). Using Excel would be a little bit of a stretch. Arnaud uses MatLab. I did it the hard way and wrote a little custom program on the PC. Basically the CSD is just an FFT / RTA on the impulse response within a defined time-window. Traditionally, the end of the time window is held in place while the beginning of the time window is shifted over successive measurements. I wouldn't mind giving you my program (its kind of alpha right now and I change parameters directly in the code) or running a few for you just to see if it works with your impulse response data. As long your impulse data contains time, real and imaginary (vector data), you should be good to go. I think Arnaud posted some of this graphs on the SR009 thread. You can see some of mine on the HF site - do a search on "headphone CSD"

No! no! arnaud is supposed to mail his SR009s to me! Actually that's OK, the ED order is supposed to come in any day now. Maybe.

Unless the picture of a bear is smudged so much that it looks like a horse. I agree some information can be gathered, but it would be too soon to assume or even be the slightest bit alarmed that the SR009 has a peak at 5k.

This would be true if the effects of the enclosures did not differ from each other. What make me suspect that they do? The deep valleys (which are wave cancellations likely from the enclosures) are all over the place. If you guys want to see properly done shit to find resonances and ringing, check out my HD800 CSD thread on HF.

I guess what I was trying to say is that none these measurements were done correctly. It's obvious with the peaks and sharp troughs that enclosure reflections weren't being compensated for. The measurements I've taken myself with my own equipment are very consistent with Tyll's. Unfortunately I don't have my 507s anymore (nor do I have any of the other headphones from those graphs), to show how wrong and useless those graphs are.

I'm betting that 4kHz peak and the following trough is a result of internal reflections that would be otherwise be filtered by our ears/brains. You see a pattern of that (to a greater and lesser degree) respectively with the HE6 and O2, both headphones with similar earcup designs. Whereas this pattern does not exist with the HD650s and the Lambdas, which have a very dissimilar design. I like what I see relative to the Lambdas though.

I'm sure it's not ED, but rather ED waiting on news. I'll give it until October.

And this is too good to not copy. What does any of that fluff even mean? It means the HE-6 sounds like shit on the Peak.

For me, that hits the nail on the head. Andy, I'd be curious on your impressions of the rev2 compared to rev1 and what tube compliment you're running for it on the BA. Anyways I'll probably get a chance to find out since both EC and Audeze will be at the Anaheim meet coming up.

I've on occasion shelved down the treble on the lambdas 2-3db from 1.5kHz upward. I don't bother trying to fine tune FR. It's kind of fruitless because most of the peaks are resonances or stored energy in the time domain that can't be really eliminated. And you are still going to get the same non-linear distortion relative to the signal anyways. The Behringer stuff is not too bad if you bypass the output stage after the DAC chips. The AKM chips have a voltage output. I think Behringer still uses the AKM4393, which doesn't sound too shabby to my ears. You can tap into the DAC chip output pins off the ribbon cable from the main board. Then either couple with a transformer or cap and feed your amp directly (assuming your amp is easy enough to drive directly from the chips.) Keep cable lengths short.

Personally, I strongly believe the reverb effect is a function of the specific recording and FR of the LCD-2. For studio recordings with artificial reverb (some pop, arena rock, e.g. Pearl Jam - Ten, the effect is very evident. For classical recordings, I heard none, at least none that wasn't natural sounding. As for the FR playing a role, the LCD2 is midrangy relative to many other headphones which typically have bass hump and no massive drop after 1kHz. Plus, I think the LCD2 has a small hump at 1KHz before the drop-off. This relative midrangy effect may make more evident any reverb effects introduced in the studio or during mixing. For those who hear the reverb, try one thing with EQ: bump up 100Hz 3db with a low Q, shelf up treble past 1.5KHz 3db, and notch down 1Khz -3db with a high Q curve. Voila - the reverb goes away.

I bet there's just one dude working in some shack. I thinking Yamas is where the DHL truck is when you turn around, go down south, and look west. This was probably a large reason why NeedleDoctor dropped STAX. I spoke with a NeedleDoctor rep. about this (Yamas' lack of responsiveness - or even giving a shit) about a week before they decided to not carry STAX anymore.

The Super 7 will be less than the Peak/Volcano. I believe Craig said ~$1500 at the meet, though he mentioned he still needs to find a source the transformers. They are really different amps though. The Peak is all about transparency. That A/V Playback Review of Peak/Volcano describes the Shuguang BT tube more than anything else. Pop a different tube in there and the amp changes. That amp is so unrelenting in its transparency that I prefer to keep away from the cleaner tubes like the metal base Sylvania WGT/VT-231. As for the Super 7, I wouldn't call it ultra-transparent, although for the large part it could be a function of the output tubes I heard it with (the russian Tung Sols). But it is plenty of fun - everything sounded good on it (HD800, LCD1, LCD2, ATH-AD2000, HE6) except the Edition 9.

Sell it and get a proper source, otherwise what's the point of it all? The PWD can be had for significantly less than its MSRP.

Haha - the Lambdas are ... well Lambdas, and I know you like the thicker more well-bodied presentations. To be honest, I shelf down the treble from 1K with EQ most of time with the 507s. I may just sell off the rest of my dynamics and pick up an O2 just for the heck of it because I get this feeling that the 009s will come in later rather than sooner.