[richard51]

I just bought a K701... After my mods there is no absolute defect whatsoever and the 701 beat my 2 stax by a good margin , and reduce the HE 400 to dust... Only the akg k 340 survive with the best natural mids to die for that exist probably on less than 1000 dollars headphones market... But the k 701 trail it, not too much distant behind it, and are better than the 340 with soundstage with a very great margin, imaging are equals, but the confort of the k701 is, even after the added little weight of my mods, abyssally better than the 340 ( more heavy,too short cable, ears contracted in the enclosure).

My mods are mechanical isolation, EMI isolation, on all components, central electrical panel and headphones included... I know I sound crazy,but I am very proud of myself for being able to create natural 3-d sound with 1000 dollars for my audio gear, all in all, including headphone,dac,speakers, amplifier...I know for sure now that almost all review are of limited audio value if you do not implement these mods including room treatment for the speakers...Upgrading frenzy is for me a past disease... There is a better headphone than the AKG 701 or 340, but trust me his cost is not one thousand dollars... My rant is only an information to the newcomer for the immunization against the upgrading disease...For almost all the others it is too late...If you are very rich you dont need to read my post for sure, it is a post for poor audiophile...I cannot imagine guy with 25 thousand dollars systems who will not consider me with pity.... But I am no more envious a bit and I listen music without afterthoughts now

 

[notengewirr]

Due to the bass mod ( port hole ), the K701 clearly suffers from bass precision below 30Hz !
The driver starts loosing control under the 30Hz range.
A modded 701 sounds more bass heavy for sure , but the low end becomes more imprecise. Sounds below about 30Hz are played unclean and starts fluttering.
What you hear is only suggesting a clean tone.
Test it with high quality sinus tones ! Do not use youtube or bad mp3 encoded demos.

 

[eimis]

Due to the bass mod ( port hole ), the K701 clearly suffers from bass precision below 30Hz !
The driver starts loosing control under the 30Hz range.
A modded 701 sounds more bass heavy for sure , but the low end becomes more imprecise. Sounds below about 30Hz are played unclean and starts fluttering.
What you hear is only suggesting a clean tone.
Test it with high quality sinus tones ! Do not use youtube or bad mp3 encoded demos.

Interesting. Looking at the graphs before and after the mod doesn't suggest that, does it?
https://www.innerfidelity.com/images/AKGQ701DIYModifiedMarcoGVBassMod.pdf
https://www.innerfidelity.com/images/AKGQuincyJonesQ701.pdf

 

[notengewirr]

My 701 is a 2006 model with serial below 9500.
i did the mod years ago. First i started with some modding in the ear-cup area...different foam/fabric in front of the driver.
The same i practiced with the Beyer-T1, 770, HD 600 with similar results.
For example the AKG 712 uses more "compact-structure" foam for the ear-cushions. The result is a clearly better low end with a very clean sounding 30-20Hz range. Even at higher volume the tones has the right tune. With the modded 701 a lot moving air is audible. Tones below 25Hz are more and more buzzing and fluttering air.
i believe the 712 driver is the same construction like my 701 driver , nothing special, same specs , same design.
It looks absolutely similar.Only the foam of the ear cushions changes the tune of this hp drastic.
The only stupid thing about my 701 is that I lost the original port hole covers. so i can not compare them exactly

 

[notengewirr]

in the 2. link MarcoGv Mod you can clearly see the distortion in the lower band raises disproportionately !

 

[eimis]

in the 2. link MarcoGv Mod you can clearly see the distortion in the lower band raises disproportionately !

Ah yes it does, looked at the wrong graph

 

[notengewirr]

even the impedance / phase curve bumps a bit in the bass range

 

[MrPhilicorda]

I've been curious of the bass mod for a long time and finally today I took the plunge. I did some measurements too, see below.

I have the K702 but they have taken the back seat since I got the Sennheiser HD 600. The Senn's really blew my mind when I got them. Recently I felt drawn to the AKG's again so I took them out for testing and now I see them differently. I can appreciate the detailed top end and tight bass, and the HD 600's can't compete with the amazing soundstage. Only drawback with the K702 is the lack of punch in the low end IMO, or perhaps it's the sparkling treble that keeps you from turning up the volume so they end up feeling cold. Either way, the bass mod felt like the logical step to take.

Looking at the measurements below it's really amazing how the mod seemingly only affects the curve below roughly 100 Hz. I wasn't too impressed when I actually listened to them though. Where as the bass in itself sounds lovely the whole signature now felt more V-shaped. I don't know if it is a psychological effect but the treble somehow now felt dirtier and harsher. I think it might be because the higher bass levels to some extent masks the midrange and thus puts more focus on the treble region. All in all it wasn't a bad sound but I think it messed with the basic character of the phones so I reversed the mod after my initial listening tests. I think the K702 is all about detail and clarity and this mod compromises that aspect in my opinion. I think 50% of the effect would be enough.

In the graph below the blue line is stock K702 and the red is with the bass mod:

 

[Dr. Q]

I'm not sure this is widely known, but it looks like this is the change between the k701 and the q701. My Qs did not have anything there.

This significant information for me. I've been using my Austrian K701s for about a year. After picking up a pair of Austrian Q701 and using them for the past week, then going back to my K7s, I much prefer the un-enhanced K701s. Like a good camera lens....I want clarity first and foremost. So, I'm going to experiment and cover the bass ports on the Q7s with different materials and see what the result will be. Does anyone know if the K7 and Q7 drivers are identical?

 

[Dr. Q]

This is a very important piece of information!
All k7-owners should be informed about this.

I just took the center caps out of my Q7s to have a look at the bass port. It's covered with exactly the same material as the K7s. So, what's giving the Q7s the bass boost (over the K7s)?

 

[MrPhilicorda]

Regarding the difference between K701/Q701, according to AKG themselves the only difference is cosmetic, as can be read in this Facebook post:

https://www.facebook.com/pg/AKG/photos/?tab=album&album_id=425309636620

To answer your questions on the what's unique about the new Quincy Signature Line, we'd like to let you know that Quincy Jones himself worked with us to design a headphone that made aesthetic changes to reflect more of his personal touch

Why do people believe there is a difference? Has anyone done measurements or done some blind testing between the two? I seem to recall Headphone.com had measured both the K701/2 and q701 and it showed a slight elevation of bass in the latter, but that could well be measurement errors or sample variance.

 

[Dr. Q]

To be clear, I don't believe there is a difference. I know there is.... because I can hear it. I called AKG who put me in touch with their tech department to answer my questions. The tech checked the parts and specs of the K7 and Q7, and informed me that the speakers in fact are different. He also mentioned that the pads on the Q7 are more dense to retain more low end.
That's what AKG told me directly.

 

[sephi007]

This is a very interesting thread, thank you all for sharing your experience! I remember a few years ago when I tried the K701 I was not a fan of the low range, but the high and mid were very nice, so I never owned a pair. This makes me want to get a pair and mod it to see if I would like it better. Hmmmmm debating

 

[MrPhilicorda]

Ok, that is more in line with what my initial impression was. I have a vague recollection that there was an official statement back in the day that the bass was slightly elevated (by 3 dB or so) but I'm not sure where I read that. Anyway, maybe that Facebook comment was made by some sales person who just didn't have their facts straight.

To be clear, I don't believe there is a difference. I know there is.... because I can hear it. I called AKG who put me in touch with their tech department to answer my questions. The tech checked the parts and specs of the K7 and Q7, and informed me that the speakers in fact are different. He also mentioned that the pads on the Q7 are more dense to retain more low end.
That's what AKG told me directly.

 

[MrPhilicorda]

Ok, more measurements showing one simple additional mod that in my mind improves the bass mod to the point that they actually become *seriously* good.

I'm doing mixing work in a studio and so far the Sennheiser HD600 have been my holy grail because they have such a natural representation through the whole frequency range. Only thing I'm missing with them is some extension in both ends. In other words, some more oomph and some more sparkle. This is why I sometimes go back to my old K702 because they have the sparkle, but on the other hand they are lacking in the oomph department.

A few posts back I wrote about my thoughts of the bass mod and included some measurements. As stated I reversed the bass mod because I thought it messed with my perception of the treble content. This is probably is a psychoacoustic effect because the response becomes more V-shaped and the mid-range gets the backseat in some ways, thus giving the impression that treble is pushed to the forefront.

Anyway, to the point! I had some Beyerdynamic foam discs (that sit behind the velour pads of DT880/DT990) lying around. I removed the K702 earpads and placed the discs on top of the stock foam ring. They have exactly the same diameter so it's quite easy to get the discs centered properly. Then I just popped the earpads back. After my initial listening tests I felt an improvement. What the foam discs do is gently taming the treble peaks by a couple of dB's from around 1500 Hz all the way to 20 kHz. In my mind it's subtle enough to not affect the general K7xx signature with the detailed and spacious top end but just enough to take the edge of those peaks that sometimes would be a bit sibilant with only the bass mod.

Now I've given the 'phones a few hours of listening time and I REALLY dig the sound so far. Let's see how the impressions hold up but right now I'm really excited. They feel so balanced and immersive. They have the treble extension and detail, the oomph in the low end, the present mid range and that wonderful soundstage.

See below for the measurements. For some reason the low end of the modded cans look slightly different to my previous measurement a few posts back. Could be because I used a different soundcard this time or because of differing headphone placement on the rig.

Stock K702 vs. K702 with Beyerdynamic foam discs:

Stock K702 vs. K702 with Beyerdynamic foam discs + bass mod: