CHANGSTAR: Audiophile Headphone Reviews and Early 90s Style BBS
Lobby => Headphone Measurements => Topic started by: Marvey on February 10, 2015, 03:20:37 AM
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This is for the mod which consists of the removal of the foam behind the cap. Headphone was placed on the measurement rig. Foam was removed without moving the headphone on the measurement rig. (well maybe I nudged it a micrometer). R driver.
TOP: foam removed
BOTTOM: stock
(http://www.changstar.com/index.php?action=dlattach;topic=2127.0;attach=8716;image)
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CSDs
(http://www.changstar.com/index.php?action=dlattach;topic=2127.0;attach=8718;image)
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Conclusion: Mod does jack shit in terms of measurements and probably does jack shit in terms of perceived sound (given how close the three measurements, FR, HD, CSD are). Although admittedly I have not tried listening tests yet.
Overlay of the two (foam removed and stock below):
(http://www.changstar.com/index.php?action=dlattach;topic=2127.0;attach=8720;image)
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CSD looks a tiny bit better with the foam around 1K / 2 MS
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Any changes I noticed here indeed could be tossed up as measurement variation and not actual changes: http://www.changstar.com/index.php/topic,1902.msg58222.html#msg58222
I suppose I could also take a lot of measurements to verify, but I suppose it would end up showing basically no difference in the end.
So the question remains...why is that foam there then anyway?
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Try taking out the tape behind the driver instead of the foam. Just leave the foam in there. My Q701 lost midbass bloat and the bass got more balanced with better proportion between mid and sub bass with the bass port mod.
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Tried same thing.
So yellow is stock, blue is w/o back foam (only), and red is w/o front foam ring (only). Differences I get are in the order of 1 to 1.5 dB.
(http://www.changstar.com/index.php?action=dlattach;topic=2127.0;attach=8744;image)
With out the back foam 2 kHz decreases by about 1 dB or so. I think Marv's measurements show that smallish change there as well if you look closely.
With out the front foam ring 700 Hz decreases by about 1 dB or so.
I think I found this to be somewhat repeatable, but who knows, could be measurement variance. I didn't perfectly align things and > 15 kHz might be compromised since I re positioned cans.
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So the question remains...why is that foam there then anyway?
Any idea if the foam has impact on exterior sound isolation? It would have to be minimal, but that is about the only other justification I can think of ... unless someone said "shit, everyone puts foam in there, right? we probably should too..."
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If you want a really functional x7xx modification, then try this one:
Use 2-4 felt rings depending on your preference (4 used in the picture):
(http://headaudio.weebly.com/uploads/1/2/6/3/12635125/3032821_orig.jpg)
Comparison of stock K712 Pro (blue) with 2-4 felt rings used:
(http://headaudio.weebly.com/uploads/1/2/6/3/12635125/6023874_orig.png)
Other measurements and info: http://headaudio.weebly.com/clanky/modifikujeme-akg-k712-pro
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Like! :)p5
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What if one or two of them was a disc? Would it muffle too much?
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Other measurements and info: http://headaudio.weebly.com/clanky/modifikujeme-akg-k712-pro
Alas, my czech is rusty. Does all that writing between the pretty pictures include your impressions on the sound with the mods? The csd's seem to improve as well, and I would appreciate hearing what your thoughts are after listening.
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What if one or two of them was a disc? Would it muffle too much?
Yes, it would... And there would be no additional positive effect at all. I tried perforated or non-perforated discs as wel as different types of foam etc. This just works, the rest does not. :-)
Alas, my czech is rusty. Does all that writing between the pretty pictures include your impressions on the sound with the mods? The csd's seem to improve as well, and I would appreciate hearing what your thoughts are after listening.
Oh, sorry... I thought you would use Google Translator or something if any additional info (other than the graphs or images) would be needed. But of course, you can always ask about anything regarding our website's content, I will gladly comment in english.
Yes, I am basically explaining my subjective impressions of the stock headphone as well as modded one... mentioning that there is not really much else you could do with your headphones (including my opinion on the bass port mod)... and some additional stuff that is not really related to the modification.
In short, the modification is not really going to change the overall character of the headphone... It's just going to make upper mids and treble more attenuated which will:
1) Decrease shoutiness, plasticness and any signs of overly bright tonality
2) Make soundstage more natural and compact (no artificially wide soundstage)
3) Forgot to add - it will sound more bassy subjectively
The most neutral config is with 2 rings while the most timbrally correct one is with 4 rings (my favourite). But it's still the same headphones, you are not going to mistake it with Sennheiser or Beyer of Hifiman or whatever. It's still K712 Pro, just tamed.
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Yes, it would... And there would be no additional positive effect at all. I tried perforated or non-perforated discs as wel as different types of foam etc. This just works, the rest does not. :-)
Interesting. In most of my trials (by ear) with the materials I have, I usually don't like using rings and prefer either discs or even a cross of something in front while leaving the edge more open.
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That's a nice result!
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Interesting. In most of my trials (by ear) with the materials I have, I usually don't like using rings and prefer either discs or even a cross of something in front while leaving the edge more open.
My guess is that you don't really need to attenuate the signal that is going directly to your ears... You just need to get rid of some acoustically-induced problems of AKG K712 Pro construction (most probably applies to other x7xx headphones as well but I cannot be totally sure, of course).
There is really nothing in between your ears and driver, as you can see on my images - and yet frequency response as well as CSD measurements are visibly better.
To be honest, I was also shocked to find out how effective this modification is... I even re-done and re-measured the headphone once again to convince myself about it o_O
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Neat !
That's what measurement rigs are for... improving things while seeing (and hearing) what you are doing. :)p7
Could be used on other Kxxx as well I reckon.
That nasty 2k peak is lowered pretty well !
Don't have any AKG's any more (didn't like them) but if I did would surely copy it.
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I should have some K701 with me soon... The owner already tried my modification and told me he hears a warmer sound signature - so that's a good sign I guess. He will send them my way so I could do some measurements and maybe other tweaks if possible.
Just to comment on my graphs from the subjective perspective: K712 Pro with 4 rings is definitely on the darker side of neutral... My HE-500s with old velour pads (FR: http://headaudio.weebly.com/uploads/1/2/6/3/12635125/3113508_orig.png) are brighter in comparison. This is not true for stock K712 Pro (it's brighter than my HE500s).
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Would be nice to see the effect on the K7XX too.
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I wonder if this would work on k812 at all. The peaks are in different places, but the concept seems similar enough. However, the driver and housing look completely different on k812, but I have not handled it yet. Anyone know?
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I wonder if this would work on k812 at all. The peaks are in different places, but the concept seems similar enough. However, the driver and housing look completely different on k812, but I have not handled it yet. Anyone know?
http://i.imgur.com/O1nWaSa.jpg?1
Can't speak on velour pads or foam rings but I'm enjoying the K812s much more with some of this in the cups.
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Tor4,
Thanks for the felt tip pointers. I have a single layer of craft felt cut to exact donut dimensions of the stock foam. I kind of like it. I'm still preferring the K701 pads though.
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Is the felt stiff or not? More soft or rough in texture? And is A4 or whatever a specific type of felt or the size?
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Tor4,
Thanks for the felt tip pointers. I have a single layer of craft felt cut to exact donut dimensions of the stock foam. I kind of like it. I'm still preferring the K701 pads though.
A single layer of ring-shaped felt is going to do almost nothing from my tests... Also,more than 4 layers are nearly impossible to fit underneath the pads and would theoretically made the sound too dark to stand. That's why 2-4 is what I recommend.
Is the felt stiff or not? More soft or rough in texture? And is A4 or whatever a specific type of felt or the size?
Stiffer, 2-3mm thick felt... Buy two A4 size to be safe but maybe one would be enough as well. At first,fitting more than two rings will be difficult but the felt is going to adjust (compress) after a while so it won't not be as problematic anymore (though still not completely easy)'
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well, i am using the K701 pads which sound very different from the memory foam, and i assume the sonic impact of the felt is going be different. the stock pads are a little too warm and bloated in the bass for my tastes. the single layer with the K701 pads adds some warmth and smooths out the trebles to my ears, but not tipping it too far in the direction of the memory foam pads.
i'm going to play around with different felts/materials, but so far am liking it as is.
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And is A4 or whatever a specific type of felt or the size?
I believe he is referring to the European paper size. "A4" is the designation for the euro size closest to our "Letter" size (8.5 x 11).
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well, i am using the K701 pads which sound very different from the memory foam, and i assume the sonic impact of the felt is going be different. the stock pads are a little too warm and bloated in the bass for my tastes. the single layer with the K701 pads adds some warmth and smooths out the trebles to my ears, but not tipping it too far in the direction of the memory foam pads.
i'm going to play around with different felts/materials, but so far am liking it as is.
What I meant was that it's going to make some change but not as crucial as with 2-4 rings... But of course, my experience is so far only linked with K712 Pro and only with K712 pads.
As I am most probably going to have K701 with me for a few days, I could try to use these K701 pads for K712 Pro... Thanks for the idea!
I believe he is referring to the European paper size. "A4" is the designation for the euro size equivalent of our "Letter" size (8.5 x 11).
Oh, yes, I forgot A4 is not a worlwide term... Thank you for correction.
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It's the closest size, but not equivalent (http://www.happyfolding.com/files/Printer_Paper_A4_vs_letter_vs_legal.png).
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It's the closest size, but not equivalent (http://www.happyfolding.com/files/Printer_Paper_A4_vs_letter_vs_legal.png).
Touche. Fixed it. Stupid, beautiful symmetry of page sizes with sqrt2 ratio.
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The whole world should adopt the A-sized papers:
(http://www.prepressure.com/images/DIN-A0-A1-A2-A3-A4-A5-A6-A7-A8-paper-size.jpg)
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Also the metric system while we are at it...
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The whole world should adopt the A-sized papers:
(http://www.prepressure.com/images/DIN-A0-A1-A2-A3-A4-A5-A6-A7-A8-paper-size.jpg)
That is a thing of beauty.
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Tor4,
I understand what you're saying and I'm not disagreeing with your findings with the memory pads. I haven't even bothered to try the foam with the memory pads yet.
The K701 pads make the K7xx sound closer to the K701 sound signature.
Please report back with any other mods and measurements.