[Dr. Q]

Ok....Here's a real head-scratcher for everyone. So, I got my main headphones, the Austrian K701 that I use 6+ hours a day. I also have my Austrian Q701s, which I do not prefer due to the enhanced sound profile. A few days ago I decided to pick up an extra pair of Austrian K701s. After unboxing them and trying them out against my main K701s....I've found a huge difference! These phones that I just purchased sound very close in profile to the Q701! Accentuated low end, attenuated upper register. I'm dumbfounded. We're talking about AKG here. How can two identical headphones sound so different? The serial number of my main phones is 94136. The number on my latest acquisition is 87138. My next step is to call AKG and ask if they officially changed the sound profile. If they did, I've never heard about it anywhere.

 

[Dr. Q]

I should probably start another thread since I'm getting far afield of the original Bass Mod topic. Here is what I've done/learned since my last post here: To recap, I spoke to the tech department at AKG. He informed me that AKG has been using China made "capsules" (speakers) in there Austrian branded headphone for quite a while....so just because is says Austrian doesn't mean it's Austrian. (Sheesh). I told him about the sound discrepancy I'd found in the last pair of K701 "Austrian" headphones.....which have an almost identical sound profile as my Q701s (Austrian). He suggested that I order a new pair of K701 capsules and install them in my K701s. I did that....and compared them with my Original K701s which are very neutral, with Chrystal clear upper frequency. Result: The replacement speakers do not have the original K701 sound. The highs are attenuated. Conclusion: I suspect AKG was sold to a Chinese corporation, that is not interested in producing the original Austrian sound. I'll be speaking with the tech tomorrow.

 

[MrPhilicorda]

AKG is owned by Samsung (South Korea) so you're not far off. It would be interesting to see some measurements of the discrepancies between your K701's.

 

[Dr. Q]

The problem is, there is no way to be absolutely sure you're ordering the K701s with the original sound, other than actually trying them WITH a known sound source. I actually do not use my K701s for listening to music. I use them only for listening to one thing....my Kawai MP-11 piano. With my original K701s powered with an Objective 2 amp, it sounds like I'm sitting in front of a 9' grand. With the Korea 701s it sounds like someone threw of heavy moving blanket over the entire piano. I'm speaking with AKG today.

 

[xxAMAROKxx]

The problem is, there is no way to be absolutely sure you're ordering the K701s with the original sound, other than actually trying them WITH a known sound source. I actually do not use my K701s for listening to music. I use them only for listening to one thing....my Kawai MP-11 piano. With my original K701s powered with an Objective 2 amp, it sounds like I'm sitting in front of a 9' grand. With the Korea 701s it sounds like someone threw of heavy moving blanket over the entire piano. I'm speaking with AKG today.

Check foam rings under the earpads.
As far as I know, there are two original versions. The black one with more vieled sound and the grey one with crisper signature.
I have tried both and these little things affect sound very much !
Original AKG grey foam ring: https://www.thomann.de/gb/akg_foam_net_piece_k_701.htm

 

[Dr. Q]

I've tried various configurations, ie: foam/ no foam, black vs grey earpads (yes, they sound different), foam vs no foam under exterior grill. After all the experimentation, the bottom line is, the Korean made capsules are attenuated in the upper register. The Qs are attenuated with a bass boost. I just went to Wiki and read the entire history of Harmon Kardon, and of Samsung. Very interesting. My question to Samsung would be......"Why would you fix something that's not broken"? "Where is the original, reference quality K701 sound"?

 

[johanchandy]

What tape would I use to reverse the mod(I lost the original material)? I forgot if the material allowed air to pass through it or not, wondering is I need transpore tape or some duct/masking tape. Any help would be appreciated!

 

[MrPhilicorda]

What tape would I use to reverse the mod(I lost the original material)? I forgot if the material allowed air to pass through it or not, wondering is I need transpore tape or some duct/masking tape. Any help would be appreciated!

It's an airtight tape. I think the most important thing aside from that is to find a tape that adheres strongly. Something like electrical tape would probably work but I'm afraid it would fall off after a while. Needs to be stronger. The original tape was really hard to pull off!

 

[johanchandy]

It's an airtight tape. I think the most important thing aside from that is to find a tape that adheres strongly. Something like electrical tape would probably work but I'm afraid it would fall off after a while. Needs to be stronger. The original tape was really hard to pull off!

Thank you! This was helpful!

 

[notengewirr]

I remember the Tape oder round little stick looks like a fine mesh. So i do not think its complete airtight.

 

[MrPhilicorda]

I remember the Tape oder round little stick looks like a fine mesh. So i do not think its complete airtight.

Here is a close-up. I looks like a piece of circular tape with an additional layer of fabric in the middle. My guess is the only purpose of the fabric is to cover the central part of the tape so it won't become a dust magnet.

 

[notengewirr]

If it were to be completely airtight, you could have simply taken a plastic cover. Or no hole at all.
I think it is a defined permeable membrane.
There was a kind of bass reflex cover from Dynaudio in the eighties. This construction was called Vario-Vent. Maybe the "tape-mesh" is also a kind of passive radiator ... since it seems to be only attached only to the outer ring like a driver suspension....


But one thing is certain with this modification!
With the cover removed, the headphones sound much more bass-heavy. At the same time, the bass begins to flutter below 30Hz. It becomes unclean and you can no longer hear a clean bass sinus ! My unmodified AKG K612 / 712 sound clearly cleaner in this area.

 

[johanchandy]

Here is a close-up. I looks like a piece of circular tape with an additional layer of fabric in the middle. My guess is the only purpose of the fabric is to cover the central part of the tape so it won't become a dust magnet.

I undid the mod using strong duct tape and it sounds like stock, so I believe you were right. I'm guessing the fabric in the middle is to reduce reflections? On one of the youtube videos talking about this mod, a comment mentions the possible purpose of this tape as a "mini passive radiator" to tighten up the bass and to give more detail to the bass. So even if the fabric part may have made the tape seem porous it may not have been. The headphone now sounds just as amazing with classical as I remember it being, and for an all purpose headphone I'm using the hd6xx with tubes, I'm super happy!

 

[drym]

That mode is good for k701, but bad for k702?

 

[MrPhilicorda]

They are basically the same headphone, only difference is 702 has a detachable cable an later models have an updated headband.