HD650 KISS mod

TEMPLATE UPLOADED!

All art, instructions, material selections and information in this post and following posts (collectively the "SuperBAF HD650 KISS mod") are covered by the Creative Commons Attribution-Sharealike 4.0 international license. Any derivative work may be sold as long as instructions and art are distributed freely and correct attribution (mention of the name of the mod, SuperBAF, and a link to this thread) is maintained.


HD650 KISS Mod
(Keep It Simple Stupid)

MATERIALS LIST

1. Dynamat Extreme
2. Creatology Adhesive Foam
3. Foam disc (included with HD650, 3 per side after peeling them)

TOOLS NEEDED

1. Needle nose pliers
2. Scissors
3. House keys (use to prop open the grills from the side)

This is going to be my definitive HD650 mod guide. Yes, there is already a dedicated HD650 mod thread here: http://www.superbestaudiofriends.org/index.php?threads/sennheiser-hd650-love-appreciation-thread.44/

And an index to the mod variations and forks here: http://www.superbestaudiofriends.or...ve-appreciation-thread.44/page-63#post-100789

The reason I am doing this because I have gone through it all and distilled the knowledge to something SIMPLE while finally reaching all of the the goals I originally set out to achieve. I love making things simple and cutting out all unnecessary BS. This mod addresses a minor side-effect of the original set of mods with the spider and back damping foam removed: a slight increase of a few db in the mid-bass. I don’t really find this slight increase in bass necessary. In fact, I kind of wanted to reduce it to HD600 levels. In essence, I wanted an HD600, but without the HD600s minor emphasis around 2-3kHz (which seems to drive @Hands crazy), and with the HD650's more refined character.

Frequency Response Differences: Stock, older HD650 mod, KISS mod

Note that differences are exaggerated with compressed Y-axis.

• GREY = STOCK
• ORANGE = HD650 original mods with front damping removed, rear damping removed, spider removed, an damping material applied on magnet
• GREEN = KISS mod HD650

Finally, the removal of the spider secure the foam (and magnet) down might result in the magnet falling off. It turns out that depending upon temperature or related atmospheric conditions, the magnet can actually fall out of the housing. This mod works with the friction fit and makes sure the magnet stays on. I originally thought the magnet might have been glued in and that the removal of the spider wouldn’t affect anything, but it turns out I was wrong. Be sure to press the two Dynamat side-strips covering the magnet / housing down with some minor pressure for a secure fit.

Here is a picture of the KISS mod. The red Xs mark all the items that are UNNECESSARY or have a minimal affect. I would not bother with them. Out of all of the tweaks, the biggest improvement to the HD650 will be the application of dampening materials to the magnet. Only the application of the Dynamat / Creatology sandwich on the locations marked in the green Ys are necessary. I also DO NOT perform the quarter mod as I did not find it necessary running this out of the Jotunheim.


Note that I am no longer using a donut on the magnet, but instead two large strips. This is for two reasons: 1) Keeping the cuts simple; 2) Making sure the magnet stays on the frame.

The Creatology layer of the sandwich with the Dynamat Extreme is not necessary. It was done for two reasons: 1) Cosmetics; 2) Ease of marking and cutting through the Dynamat and its sticky gunk. The Creatology Foam part of the sandwich tends to help clean up the gunk on the scissors.

One of the foam discs is folded in half into a crescent shape and applied directly on top of the magnet cover the hole. I used dabs of the Dynamat gunk to secure it in place (alternatively super glue might work). Be sure to lightly press a part of the foam (about 1/2 mm of it) into the hole of the magnet. It doesn't need to be perfect, but the foam does need to be flush / very slightly inside the hole. DO NOT get any gunk into the magnet hole and have it fall onto the driver membrane. Make sure the Dynamat does not cover any part of this hole. The driver really needs to breath, otherwise you will end up with something sounding like a Grado.

Here are some additional notes for this mod.

 

Zomg, wait, did you just make an HD600++? f**k, going to get this done ASAP.

 

The back venting is effectively two layers (one layer folded on itself) of the original three layers of foam. Without any damping, mid-bass is at its highest. I thought I would get stock HD650 levels, but it turns out to be a tiny bit less than stock HD650 levels, which is perfect, and as @AMW1011 said, kind of like the HD580, which happens to be my favorite Sennheiser out of the "6X0" series. My suspicion is that pushing the foam into the hole a slight bit helps reduce the bass from stock levels, while having only two layers helps with transient response. But again, I really do feel the main difference here is damping and securing the magnet to the frame. This really seems to improve the speed, focus and microdetail.

I will try to repeat this experiment on the HD6XX, but not anytime soon. Headed overseas again. If anyone knows of any good xiao long bao places in Dubai, please let me know.

 

Very cool. I am close to it.

 

Ravi might be writing down step by step instructions. Step by step instructions are super time consuming and I might not have the time.

Nope. I'm not even sure they are really baffle ports, at least ports that actually breath through. The ports would seem occluded by the screen and then the pads. I'll double check the procedure with the HD6XX.

 

Marvey, any chance you can lay a stock 600 FR on top of this one for a comparo? I know you're bored and have nothing better to do!

 

Nope. I would need to go to EC labs, steal Craig's HD600, put new pads on them, measure them, take them back to the lab so Craig doesn't get pissed. Then I have to perform final evaluations on the Holo DAC. Then I got some other secret audio shit going. I have to finish the Batman Tumbler Lego tonight. And I need to level up my Pokemon in 3DS and finish off the final four so I can start breeding 5 / 6 IV Pokemon so my son and I can duel each other with more powerful Pokemon. I have never lost to him in any of our official duels, but he is getting better. Eventually he will outsmart me strategically or not make any errors to beat me. He already knows the type strength / weaknesses chart a lot better than I do. Then I need to buy two other preamps to compare against Freya. I need to ship my Nikon for a banding issue that was caused by their last repair job. I need to find my passport too. Then finally I would like to sit down and listen to my records for pleasure, rather than for this site. And I need to start the small Fostex driver speaker builds.

 

I don't get it, sounds like you have the time?

If figured you might already have 10 different stock 600 measurements that you could grab. No worries, I'll do it the old fashioned way!

 

Hmm. Let me check.

Take with grain of salt because HD600 pads were worn. Also taken years ago.

BLUE = HD600
GREY = HD650 KISS