[takato14]

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A picture of the mod would scar everyone for life, but the camera's out.

 

 
Driver's sandwiched between two thick layers of cotton wool held in place by a string wound tightly in a sloppy manner around the whole thing. Additional cotton wool inside the cups does whatever it is it does.
 
One might intuit that this mod would worsen the sound - but one would be wrong.

Whut. You're right, that definitely doesn't seem like it would sound good. But I'll take your word for it.

 

[takato14]

Pretty sure I'm gonna regret THIS purchase.

Just grabbed a mint-in-box Bang & Olufsen U70 off the 'bay for $80 Buy-It-Now.
 

 

 
My friend is absolutely entranced with the looks of this set, so I thought "Eh, why not?". It will be a birthday present come this September. Shh, don't tell!

However, as I knew before purchasing, the stock sound is quite dreadful. So, I'm posting this here in desperation: has ANYONE managed to mod this headphone to a point of semi-decency? My friend is not an audiophile, so they don't have to be perfect, just good enough to beat the average $20 Sony.
 
On that note, he also doesn't have any sort of amplifier, and given the fact that is is an ortho (a 140 ohm ortho at that) I'm worried that he won't be able to power it. Perhaps a driver transplant might be more feasible...

 

[kalbee]

So that's where the listing disappeared to

 

[vid]

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But I'll take your word for it.

 
Don't accept a word, man, demand measurements, and if they can't provide, tell them to get with the times.
 

 
That's the HOK with both the cotton and EQ applied, the EQ which is reproduced below. Although the difference is that the CSD plot was measured before I adjusted the ~3 kHz EQ node slightly more downwards.
 

 
The cotton mod smooths out the HOK's response <1 kHz and brings the bass <100 Hz up by about 5 dB, allowing for a very simple and broad EQ to be applied to make the important vocal region flat. In addition, the cotton brings down the treble >10 kHz and with it that pesky 10 kHz peak I was unable to get rid of with any of the many mods I've tried. The treble nonetheless retains the sparkle that I think the HOK does well. The ~3 kHz node on the EQ was adjusted largely by ear rather than to get a flat graph - it leaves a slight brightness lingering around 5 kHz, but since the aim was to keep the DSP simple and since I don't mind the extra brightness too much, I didn't muck about with it too much. The only downside to the cotton mod is that it boosts the 3-5 kHz region, but since it doesn't add any peaks or dips, it's easy to deal with via EQ.
 
The result - once you mentally adjust the old CSD plot to have a few dB less energy between 1.5 and 4 kHz - is by and large a neutral if slightly bright sound with a treble that's there but not in the face. The decay is relatively fast in the graph and can be heard to be so - the K 701, for instance, is slower, for which I think the HOK has earned the guffaw it just let out.

 

[takato14]

Ever heard of an orthodynamic driver freaking out when it tries to produce bass? I thought my cabling on the U70 was going bad at first but now that I've actually messed around with it a bit it appears to be the driver.
 
In fact, both drivers were acting quite erratically a few minutes ago. The left channel was cutting in an out even when I remained still, the tonal balance of both drivers changed on several occasions, and the volume level was fluctuating like crazy. Pressing the back of the cups and the driver together seemed to stop the channel from cutting out for a while, but it returned shortly thereafter.
 
Anyone know what might be going on?

 

[kalbee]

In fact, both drivers were acting quite erratically a few minutes ago. The left channel was cutting in an out even when I remained still, the tonal balance of both drivers changed on several occasions, and the volume level was fluctuating like crazy. Pressing the back of the cups and the driver together seemed to stop the channel from cutting out for a while, but it returned shortly thereafter.

Anyone know what might be going on?

I have a pair of SFI drivers like that too.
I was suggested to bend the metal jacket it has around it, so to hold the driver sandwich more tightly (since it was kinda loose)... I couldn't do it properly. I refitted them in a shell that puts clamps the drivers tightly and my problem was solved.
So if the U70 doesn't do that, see if you can use some method to make the baffle and cup clamp on the drivers. Assuming we're seeing the same problem.

 

[MDR30]

First check the solderings. Next step is to dismantle the driver and clean the connectors (brass ring and centre pin), which is not that difficult with the PMB drivers. But be careful with alignment, the strong magnets and the delicate membrane.

I've made a couple of PMBs work fine after this treatment.

 

[takato14]

First check the solderings. Next step is to dismantle the driver and clean the connectors (brass ring and centre pin), which is not that difficult with the PMB drivers. But be careful with alignment, the strong magnets and the delicate membrane.

I've made a couple of PMBs work fine after this treatment.

One of the solder pins is under a cloth damper, is it possible to do this without destroying the damper?

I'll try futzing around with it a little more and see if I can fix it without dismantling it first.

 

[MDR30]

The cloth is glued at the rim, you can remove that with a sharp knife and some patience and later glue it back again. If the cables are not loose, you probably have to dismantle the driver. I sanded ring and pin with fine graded abrasive paper.

 

[Hutnicks]

Hey VID! Time to get an android device. Great app out by the name of Viper4android which sits between the OS and your media player and takes over the DSP processing. And.....Lo and behold has a built in convolver and 10 band eq.
 
Mobile audio just hit a new high.

 

 

[vid]

Any thoughts here about the forward progress made by the Abyss? Tyll seemed impressed with the speed vs. stats - is this sort of thing eventually to be the leader in headphone technology?

 

[Hutnicks]

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Any thoughts here about the forward progress made by the Abyss? Tyll seemed impressed with the speed vs. stats - is this sort of thing eventually to be the leader in headphone technology?

There still seems to be an air of suspicion about those phones. The price is so off putting, that were this the mid 90's I would suspect the whole motive was to provoke a buy out on technological merit by one of the big players.
 
Impressed or no, I still have not heard the phrase "light years ahead of the competition" yet. That aside, with "pancake" drivers being the rage. the technologies of orthos and "conventional" drivers are on a collision course.
 
Unless, of course someone creates a pre-charged electrostat that can be run directly for a standard headphone jack. That ever happens, all bets are off

 

[takato14]

Any thoughts here about the forward progress made by the Abyss? Tyll seemed impressed with the speed vs. stats - is this sort of thing eventually to be the leader in headphone technology?

There still seems to be an air of suspicion about those phones. The price is so off putting, that were this the mid 90's I would suspect the whole motive was to provoke a buy out on technological merit by one of the big players.

Impressed or no, I still have not heard the phrase "light years ahead of the competition" yet. That aside, with "pancake" drivers being the rage. the technologies of orthos and "conventional" drivers are on a collision course.

Unless, of course someone creates a pre-charged electrostat that can be run directly for a standard headphone jack. That ever happens, all bets are off:wink_face:

Actually, that's been a thing for a while now... it's called an electret. A permanent charge is applied to the diaphragm (which serves as the bias voltage) and all thats needed is a step-up transformer, which is often integrated into the headphones themselves. The sound may not be exactly what you'd expect since a lot of compromises have to be made for the tech to even work, but it's certainly not a "bad" sound.

Back electrets, however, can compete with full blown electrostats. They're the inverse of stats: a permanent bias voltage is applied to the stators and the audio signal is run through the diaphragm. This implementation still only requires a step-up transformer but is FAR closer to the performance of actual electrostatics.

Both types of electrets are pretty difficult to power though, you'd need a really good amp to make it portable.

 

[bootdsc]

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Anyone interested in my Realistic Pro 30's? They need some recabling and the last owner apparently smoked, but they work.
 

 
Still have them? shoot me a pm and we'll talk turky.

 

[stratocaster]

I have given my NAD RP 18 (Kapton version) a new housing. Used Black and White Ebony for this one.