[Miori]

Sorry for my replay... I own and listened many K340 as Is one of my favorite vintage cans. In the past pads were more than now a part of the headphone tuning. So I think that in vintage original pads are better than alternatives, expecially when still available. Hi

 

[Mellowship]

Sorry for my replay... I own and listened many K340 as Is one of my favorite vintage cans. In the past pads were more than now a part of the headphone tuning. So I think that in vintage original pads are better than alternatives, expecially when still available. Hi

Thank you for your opinion.
The original pads seem to have sounded very good, but mine's and, as I believe, most everybody else's, are very old, hence dry, flat, flaky, uncomfortable.
Where can we find original pads?

 

[Miori]

It Is Easy and cheap to find because are the same as k240 and others still on sale.

 

[Mellowship]

It Is Easy and cheap to find because are the same as k240 and others still on sale.

Thank you!

 

[Mellowship]

I am really astonished with the K340. They are so good...
Sure they lack impact in the low end, but I've been realising they have a really good bass extension. This is to say that they rarely punch and rumble but the information is definitely there. I can actually listen to low end details clearly, including tonality and timbre of very low frequency information. Lack of impact but plenty of extension and quality of information? It's an easy tradeoff.
Also, I am not able to perceive the reported lack of articulation between the drivers. They seem to perfectly interact with each other.
As for the treble, it is formidable. Very natural, with no hiss or sibilance. Also very extended. Reminiscent of good old el34 tube treble presentation, with some sweetness added. Very musical.
These really do things differently, with a sense of effortlessness. I wasn't really expecting this kind of sound from a 40 y.o. design.
I borrowed a pair of HD600 to compare, and as the soundstage of the Senns is somewhat more wide and in front of you, and the bass is more present, and they are a bit more comfortable (ok, much more...) and much lighter, I'd pick the k340 without hesitation.

 

[Krassi]

being "astonished" is a good word for them.
The guy that builds me a tube amp for them bought a pair himself
I seem to have the "bass heavy" version.

When i get them back ill go and start with modding them. Pads, elastic rings and removable cable first and then i hope i can find someone that can do those dampening and re cable mods.
I am really curious how they will sound with good amplification.

 

[Mellowship]

First tweaks on the k340







Defean pads and 3rd party k5nn series headband.

The pads are much more comfortable than the old ones, isolate more hence the bass gets better. They don't seem to make any harm to the rest of the sound qualities. And now I can use the k340 with glasses.

The headband fits perfectly around the plastic mounts. It has its own elastic. Because of this I doubled the number of elastic bands to balance the tension between both systems. Now it fits like a glove on my small bald head.

I kept all original parts for retrofitting.

Next: adapting two small 3.5 stereo jack plugs on each side to use a balanced cable, using Hifiman connection standards. I'll also do this with the little changes possible to the original design, taking advantage of the fixing plate and screws on the left side and the equal place to screw a plate on the right side. I'll just unsolder the original cable from the internal wires and use them to solder to the jacks, cover them in rectractible, screw them to the cups using the existing system and let the end of the plugs floating outside the cups.

Edit: in the case you noticed, I've put the cups wrongly, but already fixed it.

 

[Mellowship]

There you go, updated for the XXI century.

 

[sorinv]

@Mellowship , can you please point to the plugs you used for this mod? I'm interested in trying this on a pair of K250 phones.

Thanks!

 

[Mellowship]

Hi

@Mellowship , can you please point to the plugs you used for this mod? I'm interested in trying this on a pair of K250 phones.

Thanks!

Hi @sorinv

All materials are rather cheap and ordered from AliExpress. See the links below:

- 4 pin XLR
- 3.5 panel sockets
- OFC copper braided cable
- 3.5 stereo jacks
- cable splitter

The advantage of using these sockets is that they have a rather strong tension, a kind of double-click when you insert the jack. Also, they fit very well below the bridge each cup has to secure the original cables. You can see them mounted on the images below.



I used a dab of epoxy glue to secure them in place. I then finished the tips of the panel plugs with a small piece of retractile, to ease the identification of each side.

As for the wiring scheme, I used the Hifiman system: each side uses stereo plugs but only the conductors for that specific side are used.
Example: the left jack has only the L+ on the tip and the L- (ground) on the ground connection. The panel plug is wired the same way. This way, it only works when connected correctly. If you switch sides, there will be no continuity.

The XLR plug is of good quality. Good solder points and contacts. Metal casing. The design resembles the Neutrik. I also got a female, to make an adaptor to unbalanced 3.5 jack.

The old cable was pretty battered. It had some oxidation and some wires coming out of the sleeves. It had to be changed. As for the sound differences, using still single-ended connections, the sound got better. More presence, better separation, the sound got better balanced between right and left. I believe the old cable was not up to the spec anymore... And I do believe using the headband metal to conduct signal is not a good choice. It might have been some 40 years ago, but AKG needs to stop it...

 

[Blze001]

I have a question regarding wiring: is there a positive/negative, or does it not matter? With dynamics that aren't marked I just do a test with my phone, since they'll only produce sound if you have the right posts connected. But I just tried that on my K340s and I got sound both ways.

 

[Mellowship]

I am not familiar with the crossover circuitry in the K340, but just to be sure, I respected the original polarities when I rewired mine.

 

[Blze001]

I am not familiar with the crossover circuitry in the K340, but just to be sure, I respected the original polarities when I rewired mine.

Yeah, I was struggling with finding out which one was positive since both were the same color. I eventually found a small yellow mark next to one of the wires and assumed that was the positive indicator. So far so good, they sound much better with a better cable and the signal not going through the headband.

 

[Mellowship]

Yeah, I was struggling with finding out which one was positive since both were the same color. I eventually found a small yellow mark next to one of the wires and assumed that was the positive indicator. So far so good, they sound much better with a better cable and the signal not going through the headband.

I just used a multimeter and marked every cable before removing the original one.
And yes, that (what I think is) aluminium headband is not proper for hifi in the xxi century. I measured some residual resistance with a cheap ohmmeter, which is not a good sign considering its only 30cm of conductor...

 

[Krassi]

I got me a lot of different pads for my four k340s and one is really striking

https://de.aliexpress.com/item/33040658281.html?spm=a2g0s.9042311.0.0.1aa54c4dpMX5rX
Its not so thick as most other leather pads and i found it to be more bass intense than other pads i tried.

For me the best pads i have tried and ill order more..
its really crazy what velour or other pads do to their sound.

for me still the most pleasant sounding headphones i have..