[dmagnan]

It might be of interest here that I have enjoyably used a (perhaps similarly) modded HD800 for several years. This mod has been offered for quite a while by a company called Stefan Audio Arts. They call it their HD800 ultra-mod, ( https://www.stefanaudioart.com/shop/stefan-audioart-hd800-ultra-mod/ ). The cost now is $379 .

From the website:

"Key original internal and external parts of the HD800/HD820 headphones inhibit, distort and close-in the sound. The HD800 Ultra-mod is a proprietary process which entails removing specific parts from the stock HD800’s internal and external assembly, treating and remounting the drivers for optimal vibration control and replacing the driver mounting configuration with a Stefan AudioArt proprietary system."

I declined one of the changes, because it makes the headphone too vulnerable to accidental damage - this was the removal of the protective mesh screen on the back of the driver. According to Stefan Audio Arts this omission reduced the improvements by 25% or so.

They also offer what they claim to be additional improvements if you get their proprietary Endorphin cable, hard wired into the headphones. Presumably, hard-wiring would improve things a little, but with the loss of ability to try out all the exotic Litz and other technology headphone cables. I also declined this.

I can testify that my HD800 was transformed by the mod, with much improved transparency and coherence, somewhat better bass, and a significant reduction in the treble peak. I don't know how these improvements compare with the mod being discussed, but from the discussion so far I think that probably the Stefan Audio Arts mod as I had it done makes less of a reduction in the treble peak, along with perhaps a greater improvement in transparency and coherence. I must mention that the mod did bring my HD800 up into the region of most of the SOTA planar magnetic phones I have tried over the years, in every respect except the bass range which though improved is still wanting a little compared to the best.

 

[SoundStageHunter]

So last weekend I finally had some time to do the mod. It was quite hard getting my hands on Dynamat Extreme here in Japan. I first want to thank @Maxx134 for this mod. It's great!

It was quite easy to do, except that the Dynamat is "extremely sticky" as warned in its packaging. That makes cutting the shapes accurately (I have mild OCD) a bit tricky. I'm only about halfway done with the mod though as I got a bit busy with work. Doing it very carefully and with a lot of breaks, totally took about 3 hours with most of that time measuring and cutting the Dynamat.

Results? I'm extremely happy! There was a significant improvement (dare I say 20%) in imaging! As such the soundstage became less congested. I can say it's not diffuse anymore. As a sucker for soundstage, this is a big win for me. It's hard to be sure, but there also might be a very slight increase in soundstage depth and height.

It's Golden Week I'm Japan so I'm going to have a very enjoyable 4 day long weekend! Can't wait to complete the mod! Thanks again Maxx!

 

[SoundStageHunter]

Hey, I'd also love tk hear more about your project as this seems like the most refined attempt at improving the 800 platform.

Has this mod ever been tested by others outside of @Maxx134 ?

I can wholeheartedly recommend it. The improvement in imaging is significant. It also feels like the edges of the soundstage expanded (as in echoes in large venues, but not the general placement of instruments and voices), probably due to the shelf liner reducing back reflections.
All this improvement without doing front dampening, silicone sheet for bass seal, and insert. Hope to be able to put those in this weekend. I'm in contact with @Maxx134 and he is kind enough to send me the insert, I only need to pay him shipping fee. Great guy!

 

[SoundStageHunter]

It might be of interest here that I have enjoyably used a (perhaps similarly) modded HD800 for several years. This mod has been offered for quite a while by a company called Stefan Audio Arts. They call it their HD800 ultra-mod, ( https://www.stefanaudioart.com/shop/stefan-audioart-hd800-ultra-mod/ ). The cost now is $379 .

From the website:

"Key original internal and external parts of the HD800/HD820 headphones inhibit, distort and close-in the sound. The HD800 Ultra-mod is a proprietary process which entails removing specific parts from the stock HD800’s internal and external assembly, treating and remounting the drivers for optimal vibration control and replacing the driver mounting configuration with a Stefan AudioArt proprietary system."

I declined one of the changes, because it makes the headphone too vulnerable to accidental damage - this was the removal of the protective mesh screen on the back of the driver. According to Stefan Audio Arts this omission reduced the improvements by 25% or so.

They also offer what they claim to be additional improvements if you get their proprietary Endorphin cable, hard wired into the headphones. Presumably, hard-wiring would improve things a little, but with the loss of ability to try out all the exotic Litz and other technology headphone cables. I also declined this.

I can testify that my HD800 was transformed by the mod, with much improved transparency and coherence, somewhat better bass, and a significant reduction in the treble peak. I don't know how these improvements compare with the mod being discussed, but from the discussion so far I think that probably the Stefan Audio Arts mod as I had it done makes less of a reduction in the treble peak, along with perhaps a greater improvement in transparency and coherence. I must mention that the mod did bring my HD800 up into the region of most of the SOTA planar magnetic phones I have tried over the years, in every respect except the bass range which though improved is still wanting a little compared to the best.

I thought about that mod too but considering the cost, I decided to go with Maxx's mod. So far I've only spent like $20. Got the Dynamat Extreme for like $18 and the shelf liner for less than $1.
Would you be willing to share with us what was done to your HD800? Maybe even post pictures of the insides?

 

[Maxx134]

It might be of interest here that I have enjoyably used a (perhaps similarly) modded HD800 for several years. This mod has been offered for quite a while by a company called Stefan Audio Arts. They call it their HD800 ultra-mod...

From the website:

"... entails removing specific parts from the stock HD800’s internal and external assembly, treating and remounting the drivers for optimal vibration control and replacing the driver mounting configuration with a Stefan AudioArt proprietary system."

They also offer... their proprietary Endorphin cable, hard wired into the headphones. Presumably, hard-wiring would improve things a little, but with the loss of ability to try out all the exotic Litz and other technology headphone cables. I also declined this.

I 100% do not recommend this method.
It augments the stock weak, and incomplete "compression damping" method, by replacing the stock screws, and add more mechanical compression of the driver onto the frame.

"Compression methods" were discussed earlier in this thread somewhere. It was not chosen because of the necessary need for excess clamp pressure, according to the density/thickness ratio of the sorbothane material, which also subject to loose whatever range of effectiveness it had, over time.

I'm not sure if the stock material is also replaced, but stock setup was an incomplete scenario because it was positioned on bottom where driver sits, and not also on top. A thin sorbothane type material, which only works with compression, and so the metal ring was to evenly apply pressure onto the material that the driver sits on.

This quoted method will place pressure point "hot spots" at the four screw hole locations, so there is no longer even pressure along driver edge, and so the driver frame itself must distribute this pressure...a flawed method.

Also, taking the rear grill off, while eliminating any effects of the rear grill, not an actual solution to the problem. It is like an amputation. They are not real solutions, so just like an amputation, it introduces new problems of non protection.

To clarify, I do not dismiss any actual improvements gained, as it does address areas of issues, and also any rear grill effects. I mearly point out how far, far less evolved and less complete of a solution, which this thread covers and addresses way better and more complete.

 

[bernie hot]

Just signed up to say thank you Maxx for your post on the mods, I have installed them on an old hd800 I was thinking of selling and it has certainly improved them from a bass perspective, stage is still super wide and for the £20 cost of materials and a few hours of effort it’s well worth it!

I deviated slightly from the instructions, I did not have any washers that would fit so I just turned the metal ring around and reinstalled. Once I locate some suitable washers I’ll remove it but so far I’m very happy with the sound.

 

[SoundStageHunter]

Just signed up to say thank you Maxx for your post on the mods, I have installed them on an old hd800 I was thinking of selling and it has certainly improved them from a bass perspective, stage is still super wide and for the £20 cost of materials and a few hours of effort it’s well worth it!

I deviated slightly from the instructions, I did not have any washers that would fit so I just turned the metal ring around and reinstalled. Once I locate some suitable washers I’ll remove it but so far I’m very happy with the sound.

Congrats! The sub bass mod part significantly increased the bass in mine. I'm not sure though if it slightly decreased the soundstage compared to when that silicone part was not sandwiched.
What was the hardest part for you? For me it was screwing in the screws through the dynamat it was too sticky!

 

[bernie hot]

Congrats! The sub bass mod part significantly increased the bass in mine. I'm not sure though if it slightly decreased the soundstage compared to when that silicone part was not sandwiched.
What was the hardest part for you? For me it was screwing in the screws through the dynamat it was too sticky!

Cutting the dynamat, then trimming to size on and off the headphone was a pain. If I were ever to do it again I’d measure the circumference of both the metal ring and the outer ring and make cardboard templates and cut the dynomat with a scalpel. I made sure the screw holes were clear of excess dynamat when I punched the holes with a small metal tube I have, just moved it in and out over and over, from both sides and pulling away any excess. As I re installed the metal ring flipped over it was fairly easy to then put the screws in.