Senn HD800 Ultimate, "Maxx" Mod
Feb 23, 2020 at 12:16 AM Post #46 of 173
That was a "colorware" special edition.
 
Feb 27, 2020 at 11:32 PM Post #47 of 173
Update:

I will be renaming the latest iteration of the mod, to get away from the rest.

New name will be HD800M, and HD800SM,
because it will be maxxed out.

It is Literally the most that can be done and squeezed out of this design, without Actually changing the headphones..

Due to invasiveness of the next & latest iteration of the 800"M" mod, possible corruption of the driver can occur if anyone tries without my methodology, as did during the initial moding of my Carbon edition:
IMG_20200227_205658.jpg
The realization that I needed a new methodology with different tools that not exist.
As if 2022 refinement made had dropped the high failure rate of over 80% to 50% during the modification process.
Therefore I have to add in cost of one driver as expense overhead.
Once complete, process is permanent and stable.

Visual measurements below:

Remember this is all done in non traditional way.
No stupid felts or foam cut outs placed inside the metal cup.
No raping of the driver front screen to voilate it's center hole to imitate Senheiser with the 800S.
No placement of rug liners to kill soundstage.

No Resonance.
No ringing.
No diffuse sound.
No small or even normal soundstage.
No dead sounds of rug liners.
No sucked out sounds.
No tame sound of SD type inserts.
No thickening of the sound like 800S & 820.
No anemic bass sound.
What is sounds like is very close to a Susvara in depth. A deeper, larger, much more neutral & non-diffused sound.

Edit**
Final tuning cleaned up trebles & lowered trebles a touch.
FR & Dist:
HD800X Final Dist.jpg

Notice no dist peaks from 1k all way up.
Had fishtank in background noise.

CSD:
March1 HD800X Final CSD.jpg

Looking from 1khz up all is less than .5ms

CSD is 30db down & extended to 200hz to see more.

The lack of slices immediately after initial sound shows how fast, clean & clear it is, compared to the density of slices in left.
 
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Feb 29, 2020 at 11:38 AM Post #48 of 173
I updated my findings on my dynamat usage:

Basically, it confirms my reasoning for damping.

It turns out that the HD800 was using a type of rubber under the driver, which required the usage of the metal ring(!) For the necessary even compression to work.
sorbothane
(in this setup) works by compression.

This confirms my idea of the necessity to dampen the driver.
In my case, I chose the dynamat route, instead of the sorbothane route.
Those are the two choices for vibration control.
 
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Feb 29, 2020 at 11:43 AM Post #49 of 173
I also mentioned the updated upgrade choice of using Dekoni ferenstrated lambskin pads, in combination with using the Specific silicone membrane that only the non-senheiser pads (mentioned earlier in thread) have.

That will optimize both wave propagation (soundstage ) while keeping bass seal (with the silicone membrane).
 
Feb 29, 2020 at 12:07 PM Post #50 of 173
I posted an update explanation about the resonator mod in first page.

With both the driver damping, and resonator mod explanation, it looks like all the Hd800 secrets are now revealed on first page.
 
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Oct 7, 2020 at 12:11 AM Post #51 of 173
Hello, I came across this thread searching for HD800 mods, I have unmodded HD800 currently. Of course, I know about and was planning on the SDR mod at least. You mention here an alternative to the SDR mod materials...

"So there was a balance to strike, and the 800S was the result. Very nice change, but not as "clean" sounding as the original.

Regardless,
This part of mod will give a very similar sonic character and signature of an HD800S.(!)
Use ONLY these specific Sennheiser "ear-tips"!"

1) Is this an alternative material to perform the SDR mod, even without your other mods? Will it fix the 6kHz etc treble peaks and overall do the same as the SDR mod?

2) The 800S has 2nd harmonic distortion in the bass compared to the 800. As far as I know, the SDR mod does not add this distortion. Are you saying these foam eartips alone add 2nd order distortion like the 800S? You said bass distortion measurements were not accurate due to noise floor, so I don't want to misinterpret the bass region of distortion graphs.
 
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Oct 13, 2020 at 11:52 PM Post #52 of 173
Hello, I came across this thread searching for HD800 mods, I have unmodded HD800 currently. Of course, I know about and was planning on the SDR mod at least. You mention here an alternative to the SDR mod materials...

"So there was a balance to strike, and the 800S was the result. Very nice change, but not as "clean" sounding as the original.

Regardless,
This part of mod will give a very similar sonic character and signature of an HD800S.(!)
Use ONLY these specific Sennheiser "ear-tips"!"

1) Is this an alternative material to perform the SDR mod, even without your other mods? Will it fix the 6kHz etc treble peaks and overall do the same as the SDR mod?

2) The 800S has 2nd harmonic distortion in the bass compared to the 800. As far as I know, the SDR mod does not add this distortion. Are you saying these foam eartips alone add 2nd order distortion like the 800S? You said bass distortion measurements were not accurate due to noise floor, so I don't want to misinterpret the bass region of distortion graphs.
Sorry late response I so busy on other projects.
Yes to all above.
All should try the foam I suggested first before any other modifications.

You only have to cut the round top as it is a bit longer than the depth of the hole.
Not even have to be exact as it compress inside a bit.
Consider it a bit more enjoyable vibrant colored version (keeping more bass & trebles), while the SDR is a more tame neutral version.
Remember that any other Sennheiser tips will not work.
Must be the specific tips I posted.

Regardless I will be progressing on the mod soon as I develop new tools to achieve a high success rate in my next mod which you see I posted above (800X mod).
Cheers
 
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Jan 23, 2021 at 5:18 PM Post #53 of 173
First off,
At The Back of driver inside area,
apply dynamat extreme in these sections:
*pic*
A0tdMzy.jpg

*pic*
swMOOPD.jpg


Once done, set aside and position rear grill mod2 over it, to get ready for closing with next mod...

Many thanks for posting this comprehensive mod and the enormous amount of time you must've spent on this.

I've just got one query regarding the step 3 above, I'm confused how to apply the dynmat shown in the above 2 photos. Do you apply dynamat in a full circle pattern or half moon.
 
Jan 23, 2021 at 10:18 PM Post #54 of 173
Many thanks for posting this comprehensive mod and the enormous amount of time you must've spent on this.

I've just got one query regarding the step 3 above, I'm confused how to apply the dynmat shown in the above 2 photos. Do you apply dynamat in a full circle pattern or half moon.
They are cut pieces to go around in a circle. Pic looks half completed in one.
 
Mar 9, 2021 at 12:59 AM Post #56 of 173
Hello I'm updating with recent initial preliminary tests using 1mm silicone ring:

HD800 Stock Imp no dust cvr.jpg
HD800 Stock silicone ring.jpg
Observation of the reduction of small consistent variations after 200u, verify that the "compression method" could be tried as a viable alternative to dynamat method, on the metal ring area.

In other words, it looks very promising to use lighter cleaner sorbothane sandwich (both under and on top) of the driver, in place of dynamat.

Next round of tests will be using actual sorbothane "ring" of 2.5mm thickness chosen at 30 durometer.
 
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May 14, 2021 at 3:53 PM Post #57 of 173
I updated initial first page post with an
initial comparison to an SDR mod, to show the difference of more upper FR above 10khz (air), and more lower spectrum:
IMG_20210514_153645__01__01__01.jpg


So this is to point out that my mod is more like an 800S, while the SDR mainly focused on the 6k ring & peaks.

For those that have good ears, you will be able to tell the difference in upper FR that comes across as "air" in the trebles.
Stock also has the "air" but any other mod than this, will "close in" the soundstage and air, as seen in this comparison.
 
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May 17, 2021 at 11:44 PM Post #58 of 173
Added more actual data of improvement over stock HD800:

Ripple at 2.5k, 47db down of stock:
hd800 47db dwn.PNG

Cleaned up with mod:
HD800 Ult 47db dwn.PNG

This is proof of the ELIMINATION of resonances from my damping methodology.
 
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Jun 20, 2021 at 3:52 PM Post #59 of 173
Hey I'm currently doing your mods, tho due to being in a far away country with no way of purchasing a dynamat Xtreme, I decided to cut a few corners hahaha, I used a damper with similar thickness with the dynamat, and for the shelf liner I couldn't find the ones exactly like yours so I find a similar with a slightly different pattern...

Tbh They sound crazy fantastic, tho I want to ask if putting the dynamat ring on top of the metal ring would make a huge difference vs just replacing the metal ring? Because I tried just covering the metal part of the ring with dynamat and they, seem to perform very well...
Polish_20210620_041129163.jpg
 
Jun 23, 2021 at 11:50 PM Post #60 of 173
Because I tried just covering the metal part of the ring with dynamat and they, seem to perform very well...
The metal has a foam layer under it, which hampers the dynamat effect of solidifying the driver to the basket frame.

IMO, Sennheiser made a mistake using foam, instead of the sobothane ring they use under the driver. I personally believe this was not as designed and a change because of cost and replacement would be easier with the foam on that metal ring, instead of sorbothane.

So if you don't want to use the dynamat as a replacement, you could try cut out a super thin sorbothane or silicone layer to put under the metal ring, and flip that metal ring upside down for more solid bond.
 
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