Want more bass from your HD 800? – Easy mod - Page 2

SteveM324 said:-
My Moon Audio Blue Dragon is a nice improvement over the stock cable. The Blue Dragon adds more bass and adds a little warmth and body while retaining tight bass. Highs seem less bright as well and transparency which was already very good gets better..

I totally agree with this.

This mod actually makes the HD800 more normal headphone. All other headphones I know have more or less closed coupling to the ear, no matter it's a closed or open headphone. The HD800 have ventilated kind of coupling the transducer with the ear just due to the steel mesh. Sticking some foam to it causes the coupling to be more headphone-like, the transducer's diaphragm again works more like a piston and less like a speaker. Congrats on the idea!

Um I never said they were, I simply said I was considering them. Cheers for telling me something I already knew though (as indicated by the word "past").

So many places I could go with this, first of all price (maybe I cant afford an HD800 at this point in time???). Second of all the rip off that is the HD800 locally (about $2400 and we are unable to buy it from the stores best country).

I added it merely as a disclaimer for the reasons for my asking (to avoid being ridiculed myself) but it looks like I was anyway. I love head-fi.

^You need to relax.

Cleaning sponge...

Hi Jazz and all:

This week I tumbled through this thread and got excited about the mod that Jazz came up with. I was actually a bit dubious about IpodJ's mod as it seemed quite difficult to control / repeat (depending on the clothes you use and such) and I could not quite understand what physical meaning it had. Plus, it indeed felt a tiny bit offbeat when applied to a headphone that is truly the result of years of R&D...

Then, reading Jazz's thread, he made a very good point about the frame at the back of the headphone which is not acoustically transparent like the rest of the grill. This got to affect the sonics and there was no other way around for Sennheiser (apart from placing it toward the back of your head and making it as narrow as possible):



A couple days after reading this thread, I was wondering where I was going to find some felt. On that evening came in the mail a small gift from our newspaper company, a ... sponge ... What caught me is that it's a special sponge made of melamine foam. Melamine foam, amongs other things is what is flown into space as part of launch vehicles. It's used for its good sound absorption properties while being extremely lightweight:



I could not have dreamed a better sound absorber to try to mod my HD800! It also came in just about the right size, makes you wonder sometimes ! God's gift ? . It turns out it's also extremely easy to slice through so soon I had the perfect shape to cover the frame:





Although the sponge came as 20mm thick, I sliced it in half because I did not want it to touch my ears when wearing the headphones and I knew that this thickness was sufficient to get sound absorption only toward 3-4kHz up. I work on acoustics daily and am thus lucky to have access to simulation software to predict noise and also performance of given layers of porous materials. I created this graph which shows what percentage of the sound incident on the foam gets absorbed and compared the melamine foam to glass wool of the same 10mm thickness. The melamine foam adds the right amount of absorption (about 50% of the sound waves hitting the frame are absorbed from 2kHz up):



I then placed that sponge in behind the screen cover:



Placed the cover back in, it seems to fit just fine:



Et voila! I think that Jazz's comment was spot on: you get spurious sound reflections of the frame and it clearly affects imaging. With this mod, the soundstage has moved several rows in front of me and become so much more natural. Before, I always felt the soundstage to be very wide and deep but frankly not quite up to notch with speakers. Also, I felt my Edition 9 offered more credible sense of depth before this mod. It's no longer the case.

Second major point, the absorbing material has tilted the frequency response of the phones a bit and the tiny bit. The upper mids / highs emphasis has been taken down a notch to the point where even my not so stellar recordings come through just fine. At the same time, the bass does feel more forward but that's just due to the taming of the highs.

So, I will conclude like this: many thanks to Jazz for your thoughtful comments, you have helped me transform a wonderful headphone into an even better performer, this was free and so effective! I imagine it would not be difficult for Sennheiser to come up with a replacement screen that has in-built absorbing pad, Sennheiser, are you reading this ?

A couple more things: I haven't checked in the stores but I assume one can find such sponge anywhere? Actually, I was surprised as melamine was really expensive stuff in the past and only used in aerospace applications, wherever weight is of major concern. Given the high tech nature of the HD800, the melamine foam fits right in IMO!

Happy listenings,
arnaud.

Part 2

I feel I may have gone a bit too far with the re-voicing of the phone...

I just tapered off the edge of the foam on the earpad side (slicing to half the thickness starting from the upper base of the trapezoid shape). The thinner you make it, the higher the frequency from which it starts to be really effective:

It seems like this is about the right balance (5 to 10mm thick). I got some sparkle back and it sounds mighty good!

arnaud

Humm, we're getting borderline geeky here but I could not resist showing off what marvels this piece of software can do in a couple of clicks (litteraly 10 minutes to make this from scratch) . I quickly drew the actual shape of the foam pad to predict it's actual absorption performance (previous results were for flat stock material):



I then meshed the top and bottom surfaces so I could generate a thickness map:



The following grab is the projected thickness onto the lower plane. Blue means minimal thickness (5t here) and red is the max thickness between the two faces (10t here):



The software then computed a composite absorption material with various melamine foam varying from 5t to 10t in .5t step according to the color map. It came up with the corresponding percent coverage and resulting absorption performance of the actual trim piece, shown in red here:


Well, the result was kind of predictable but for those who want to precisely know where this mod will affect things, you have some form of explanation. Now if only I had a dummy head to measure these headphones...

Arnaud

Congrats IPodPJ for pioneering this mod in the first place.

Congrats Jazz for further refinement and articulation.

Congrats arnaud you further refined again and have also given is some substance and cred.

Well done team HD800 modders, I’m going to try this mod again, (the original IPodPJ was a little heavy handed for my tastes) - with arnaud’s up to date version and report back.

Hi Jazz, from experience, the velvet pad really only targets the highs. I have generated a new absorption plot comparing a typical car seat cover (assuming 2mm thick velvet which is generous based on the pics you posted) to the melamine foam:



As you can see, for a given covered area, you get much more absorption from the melamine foam, which is partly due to thickness used. I think you are using at least double the surface area from mine with your black velvet (so the pink curve values should be doubled to compare apples with apples). But even then, the velvet still probably provides only half the amount of sound absorption of the melamine pad. On the other hand, the velvet pad really targets the highs (6kHz and up) and does not eat so much into the mid-/highs like the foam. Probably worth to compare the two mods.

Actually, this is strictly a problem with non-porous material. The pads you are adding to partially prevent acoustic cancellation on the back plate are definitely affecting the effective acoustic volume. The nice thing about melamine is that it really is just air (99% of the volume is air to be precise). So if anything, you get an effective larger acoustic volume as far as Thiel & Small parameters are concerned. I don't think it is relevant to the design of open back headphones though (I could be wrong).

Well, to tell the truth, I was pretty happy with the phones to start with. I just wanted to take the mid/highs down a notch as poor quality recordings were not always enjoyable. The mod did this and much improved the soundstage. I am afraid that covering the steel mesh will have negative impact on imaging (I believe one reason why the HD800 soundstage is so spacious is that the engineers have tried to minimize reflections).

cheers,
arnaud

Quick update...

Jazz was kind enough to send me some sample velvet as I wanted to try his mod. I also could find melamine foam sponge in nearby supermarket so I sent him off some foam too. I tried the velvet mod over the week end. I ended using dual layers of size about 10cm x 3cm covering roughly 40% of the earcup, basically the rear side.

I think I am using more velvet than Jazz but still the effect is "subtle" comparatively to the melamine foam. To be honest, the velvet does not alter enough the balance in my taste so I switched back to melamine foam. The melamine foam mod basically makes the tonal balance of the HD800 much closer to HD650 while yours is much more subtle. I can see people liking either of the mods better. In my case, I tend to listen at lower to mid volume so maybe I tend to prefer a warm presentation. The nice thing is that the amount of detail retrieval is still amazing with the HD800 after the melamine mod, I am sold on this now!

Thank you again Jazz for sending the velvet, I hope you will receive the melamine soon and post your findings. And who knows, maybe you will come up with a better arrangement of the foam! One more thing you may appreciate: the velvet tends to leave lost of pieces because of peeling in the cut zone. The foam behaves very well in that regard so more convenient to use. Finally, as you may know, you can make the foam as thin as you need to reduce its impact...

cheers,
Arnaud.


arnaud.

It's cool to see people taking full ownership of their headphones.

Good work guys. I'm glad to see you're trying to improve on the original mod. I will have to try some more materials when I get a chance. But for these ears I think the cotton T-shirt works best, as it allows most of the sound to pass through it as it does normally, with a little bit of absorption. It still maintains all the detail as before but brings the image into focus and allows more bass detail to be heard.

Each HD800 varies in tonal balance. When at the last meet, I tried Uncle Erik's HD800 on a vinyl rig with my cable and compared them to my HD800 with the mod. His pair had a little more bass than mine did. So you won't be able to find one mod that will work for everyone, since all pairs of HD800 measure differently.

Here's the link to the original thread. People really sidetracked it, but check out the first post if you haven't already.
http://www.head-fi.org/forums/f4/hd8...thread-446585/