Sennheiser HD690S

Final mod, what started with the 690 finished with the 690S.



- larger magnet with 80% stronger magnetic field.

- 3D printed removable-ish spider. This is far, far more important than I thought going through multiple support frames, learning along the way. Also took the most time.


- paper screen from early HD600 as show by Tyll:


- revised damping

- the most important part, also the most unassuming, driver back foam
This took the second longest time, tried 20+ different materials, settled on three, one is the overall victorious

The middle one was chosen after extensive testing. The left one is stock 650, darkest of the bunch, closest to the stock sound. The right one is a 30ppi 4mm foam, most neutral, can work better in isolated cases, least coloration.
The front and grill back foam is of critical importance as well, annoyingly so.

The HD690S has changed my portable setup, increased sensitivity means I can use low gain on WM1A with headroom to spare, nice synergy. Even out of my phone the 690S can easily exceed expectations. Feels like doubling horsepower on a car, very responsive and nimble.

Sound wise it's like a hybrid between HEK and MySphere on my setup, for my tastes etc. etc.
For desktop new pads are needed for best result, for portable used shallower pads work better with the sony.

HD690S semi closed, wood reverb:

Makes even the K1K look normal, 0.5Kg. This ditches the foam damping, adjustable vents, somewhere around 13mm² I found the ideal split in two locations.

I know why I liked the Eikon and why many want ZMF, the wood cups undoubtedly add something. Much lower leakage, can use in bed at lower volumes and not disturb my better half, win-win.
Fully closed it kills the detail, the large cups keep the soundstage to 98% the level of using stock grills but with more hefth.

There's still a lot of fine tuning to do on the modeling side, 3D printing is an interesting journey and I'm still a noob. Sound wise, tuning is final, no more messing with it. I've learned so much about why the 650 sounds the way it does, the driver is exceedingly capable. Tuning was done by ear, started with black box testing, swapping large bits to see how the sound changes, going incrementaly smaller, getting multiple data points. Must have had over 100 prototypes, each was an evolution.
The WM1A was the most used, followed by the Crack with the stock cable. Only the few final generations were used on Stellaris for selection, where different cables were used. Destroyed three headphones in the process while messing with the magnets.

Really happy with the end result, HD580,HD600,HD650,HD650M,HD690 are obsolete for me now.
The king is dead, long live the king.

 

Can you provide measurements with stock HD650 in comparison please?

 

Working on it, curious myself though I'm not one for measuring things, once I have them I'll post.

 

Cue loaner tour requests *cough cough*

On a more serious note looks like the open 690s isnt much heavier than the stock 650/6xx?

 

The same weight basically, 50g extra, not a big deal. I am enjoying the wood cups but the weight is felt in my neck after a full day.

I am looking for another 650 to mod and use as a loaner, KISS or ones with the spider removed are prime candidates. What is a permanent destructive mod can be repurposed for a 690S. The beauty and point of this is not being limited to unobtainable materials or materials from the original headphone. I know that anytime I want I can rebuild them from scratch provided I stock some key components. I can't imagine having a different portable setup than these with WM1A or equivalent sony.

 

Can't wait to hear it and compare with my hd600.

What were the biggest difference with just the magnet change?

 

- increased sensitivity, going from 110..120 on the DAP to 100..110
- faster/better driver control, this trickles down to various changes
- more extension especially up top
- very shouty

 

Many thanks to @Hands for providing measurements.

Not sure what they're suggesting apart from my preference for more top end while retaining smoothness.




With stock HD650 foam which I find a bit less airy.




With special Hands sauce to bring it closer to HD650




While interesting they tell nothing about the dynamics, blackness, speed and control, the highlights of this mods. It may be sacrilege to say but I want more sparkle in the HD650, fun without sacrifices.

The increased treble I prefer is due to tube selection set mildly warm which works far better than a neutral setup with un-emphasised highs IMO.

Some interesting ideas have surfaced on damping well worth pursuing at some point.

 

Can't see any of the images @m17xr2b. Imgur link?

Edit, visible now! Third set looks great IMO, especially the distortion cut.