New K340's on the way!

[philodox]

"building me give me"

Goddammit! I hate not having an Edit function.

[TheSloth]

I received my modded K340's back from Larry a few weeks ago. I have to say that I preferred the sound before - to my ears, despite an increase in isolation, I felt the entire response tipped up to the treble, with a slight discontinuity between the two drivers (an example of which would be hearing the same HF harmonics sticking out as distinct from the fundamental when they ought to have blended in). The sound was clean, but as far as I am concerned on the brighter side of neutral. I decided to undo some the reversible mods one by one - first I removed the sealant tape that was covering the back of the driver housing, opening up the enclosure somewhat - huge increase in bass, too much in fact. Larry had used cotton wool to damp the enclosure, but for some reason had installed it in a semicircle covering only half of the back of the driver. I removed that, and found a better overall balance. However there is a relatively significant resonance around 250hz in this current configuration (no damping, open backs), making the bass muddy and bloated (noticeably more so than a 650 if that gives a reference point). I'd be quite curious to see what effect the original cotton ring has on the sound.

[philodox]

Damn, sorry to hear about your problems with the Headphile mods.

I've always liked the no cotton, taped back on my pairs. Maybe aerius can provide some more suggestions as he has spent quite a while tweaking his.

What type of cable did you go with again?

[aerius]

Told ya not to get the rescreen.

Ok, seriously, you are now in for a world of fun, because doing the fine tuning is a pain in the ass. You will need blue-tak, fibre stuffing stuff, electrical tape, and lots of free time.

First step, seal the back and play with the stuffing. Get one of those polyester stuffing sheets they use for making quilts and cut rings out of it. Or use good old cotton balls. Experiment with using more or less until you come to the best balance of sound, it's unlikely that you'll find something perfect so just try to get as close as you can.

Then figure out what you don't like about the sound. If there's too little bass, poke a couple small holes in the tape and see if that helps. If you have resonances, then it's time to blue-tack away. I put a dime-sized patch on the housing behind each of the passive radiators, then put some on both sides of the plate that holds the passive diaphragms. Listen and check, you may need to adjust the stuffing amount after blue-tacking.

See how that works, and if you still can't get a good balance let me know.

[TheSloth]

Told ya not to get the rescreen.

Well considering the design of the rest of the headphone, I do think it might have been taken into account with the design. There are equations to determine the size of holes in a screen versus frequency response, and I'm sure AKG gave them at least a passing glance.

Anyway, not the end of the world. I got BlackMax cabling. I didn't like the fully sealed back - too compressed and top heavy. I like your idea of partially closing it up, with some small holes in the tape. Might give a good balance of sound. I also think that the rear of the housing is a bit resonant, so a nice covering of blutack might help there. Once I've sorted out the back, I'll experiment with damping.

[philodox]

Bah, I doubt this is the rescreen's fault. Be carefull with that bluetak... it can do some bad things to the sound as well.

Other than that, I think aerius gave you some very good advice there. I knew he would.

[aerius]

The key to doing the tuning is to change only one thing at a time so you know which changes are doing what. It's a pretty obvious thing but many people (including myself at times) tend to forget that and/or lose patience and start changing more than one thing at once. Sometimes you get lucky, usually you don't, and in either case you have no idea which change made the improvement. Good luck, and I hope you find a tuning you're happy with.

[TheSloth]

Well just to experiment with the screen, I've just bought another K340. I'm very curious to see how these two will compare when the second one arrives. I like K340's!

[philodox]

Awesome, can't wait to hear your results.

[TheSloth]

Awesome, can't wait to hear your results.

Well I got my second pair of K340's and did some listening, and some swapping of pads and screens. To cut out all the stages, I do actually prefer the original screen - it just seems slightly more balanced throughout the spectrum, though there is a slight reduction at the very top end. It gives slightly better continuity between the two drivers to my ears. I can see why people would want more high end, but it sounds a little artificial that way to me.

I never bothered to keep the original pads from my first K340, which I now realise was a little silly because the pads change the sound more than any other tweak. The velour pads are nice, but the inner dimension is just a few mm smaller than the original, possibly constricting the sound a bit. Also, because of the lack of reflectiveness of the velour, it has different acoustic properties. The velour seems to enhance the mid-bass, very slightly reduce the midrange and therefore highlight the treble a bit. The pads on the second pair were however too compressed to compare more than that, so I might get hold of a newer pair of the original pads for comparison.

For now, I am running them with the original screens, cotton behind the drivers and open back. Strangely close to stock, huh...?! I would however like to get hold of the original cotton piece from behind the drivers, or at least a piece of flat circular cotton that is equivalent just to know exactly how these did sound stock.

[philodox]

The velour pads are nice, but the inner dimension is just a few mm smaller than the original, possibly constricting the sound a bit.

Strange, that is definately not how I hear it.

I think part of the confusion here comes with the two very different sounding stock K340's and the combination of mods used. As you have noticed, every little change tweaks the sound a little bit. I guess I am just happy with the total of the differences, where it didn't work out for you. I am glad you are getting closer to the sound you want though.

[TheSloth]

Latest update - I'm back to the Headphile screens, a ring of cotton behind the driver, and some thinned out cotton wool to sort of close up the hole at the back. Best balanced I've found so far.

[TheSloth]

And now the left electret has started squealing at certain frequencies... AAAAAAAAAAAAAAAAAAARGH. DAMN YOU AKG for having none left.

[Iron_Dreamer]

And now the left electret has started squealing at certain frequencies... AAAAAAAAAAAAAAAAAAARGH. DAMN YOU AKG for having none left.

Ouch, I don't envy you K340 obsessed freaks

[philodox]

And now the left electret has started squealing at certain frequencies... AAAAAAAAAAAAAAAAAAARGH. DAMN YOU AKG for having none left.

Probably just some cotton stuck to part of the electret.

At least you have extras, the rest of us dont!

[TheSloth]

I'll investigate later, but I actually don't have spares - I just sold the other/damaged on to PsychoZX. If I'm going to have a second K340, I'd rather it was a fully functional stock one for comparison/change, rather than the slightly mutant one that I ended up with.

[PsychoZX]

I'll investigate later, but I actually don't have spares - I just sold the other/damaged on to PsychoZX. If I'm going to have a second K340, I'd rather it was a fully functional stock one for comparison/change, rather than the slightly mutant one that I ended up with.

it won't be slightly mutant after I get done with it.

[philodox]

I'll investigate later, but I actually don't have spares - I just sold the other/damaged on to PsychoZX. If I'm going to have a second K340, I'd rather it was a fully functional stock one for comparison/change, rather than the slightly mutant one that I ended up with.

But I thought you had the electrets replaced by AKG and they let you keep the old ones? From what I understood there was actually nothing wrong with the old pair? Or was it the bass drivers you had replaced?

As I said though, open them up and make sure there is no cotton or anything stuck to that left electret or between the electret and the dynamic driver. I would also doubt check that the wiring isn't shorting or broken somewhere on the left channel.

[TheSloth]

They replaced all the drivers, but the electrets were the dead ones. They just used to replace all the drivers for matching reasons.

[Tachikoma]

I'm going to recable a pair of K340s to 4 pin XLR soon, using OCC copper , so which cable layout do you guys think I should use? Flat/twisted/leave the strands hanging in the air? I _was_ thinking flat, stax cable like flat, but from what I've read the flat cable configuration would have high capacitance, which contradicts stax's "low capacitance" claim.

I'm not sure which version of the K340 I got though, the treble's definitely there while the bass isn't, but I'm currently driving them out of a cmoy

[grawk]

128 wire 28ga silver braid

[Tachikoma]

128 wire 28ga silver braid

awesome. something that isn't entirely impossible to build with my bare hands would be better though

[Dusty Chalk]

I'm going to recable a pair of K340s to 4 pin XLR soon, using OCC copper , so which cable layout do you guys think I should use? Flat/twisted/leave the strands hanging in the air?

As far away from each other as possible, with spacers.

No, seriously, how about shielded?

[TheSloth]

As far away from each other as possible, with spacers.

No, seriously, how about shielded?

Why would you shield a headphone/speaker cable?

[Dusty Chalk]

Because he's going balanced?

And yes, admittedly, it's more correct to say "faux-shielded", meaning it's shielded for only part of the length.