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Dampening Modifications to Fostex TH600 Headphones

Discussion in 'Headphones (full-size)' started by sweetmeat, Dec 30, 2014.
  1. Sweetmeat
    I just finished performing the Lawton acoustic chamber dampening modifications on my TH600 and it's the best 50 dollars I ever spent. Like lots of guys, I upgraded from D2000 headphones to TH600 because of the D2000 missing midrange. However, the TH600s seemed to replace the authoritative sub-bass of the D2000s with a rather annoying mid-bass bump. Also, the TH600s had a harsh upper midrange bump that dominated the treble. I considered selling them but used TH600s are hard to get rid of, unless of course you want to practically give them away.
    Mark Lawton to the rescue. To avoid throwing good money after bad, I purchased his Level 1 mod kit and installed it myself. He was a good chap to work with, and I'm convinced he knows his stuff. However he estimated 1-2 weeks for shipping and it was 4 weeks. Also, the kit was missing a few pieces which he kindly provided after an additional delay. So after a few weeks, I was finally ready to perform the Lawton acoustic chamber dampening modification to my TH600s.
    The kit is designed to dampen the TH600s in 3 locations: earcups, and 2 concentric metal rings on the backplane. The inner ring correlates with magnet size and the outer ring correlates with diaphragm size. I applied the standard "tap" test to these locations and they all rang like a bell, so Mark selected the correct locations to dampen. Hard to believe headphones this expensive could ring so much. After the kit was installed, I retested and determined the ringing had been highly attenuated.
    The kit includes numerous precut rubber pieces with glue already applied to one side. If you are familiar with Dynamat, the Lawton rubber is much harder and thinner. Three olive rubber pieces are provided for each earcup (6 total), and 2 black rubber pieces are provided for each concentric ring (8 total). There is an extra black rubber piece I didn't use. Finally, a gray foam piece, with 2-sided tape already applied, is provided for each earcup (2 total). I suggest you ensure all the pieces are present before beginning your TH600 modification.
    I installed the kit according to the instructions Mark provided me, but he left out a few details. First, most of the rubber pieces are only approximate size, so they must be pre-fitted and trimmed to fit. However the round pieces on the concentric rings already fit perfectly. Second, for any rubber piece that does not fit flat, the provided glue is not aggressive enough to hold it in place. I added a very thin layer of superglue to the black rubber strips, and I used ample amounts of 3M 2216 epoxy adhesive on the olive rubber pieces in the earcups.
    An application note for the 2216 epoxy: This adhesive is excellent but expensive, I had some left over from  a previous project. A cheaper substitute would be a thick superglue such as Loctite 1752196. Thick adhesive is necessary because the olive rubber pieces are distorted so severely during installation, there are gaps that must be filled in order to maintain proper contact with the earcups. The 2216 epoxy requires the parts to be clamped overnight, I can provide the clamping procedure if anyone is interested.
    I tested the TH600s with the dampening kit and OEM earpads installed, using my Burson Soloist. The difference was quite apparent between undampened TH600s. The mid-bass bump has shifted downward to provide a smooth, powerful low end. The harshness in the upper midrange is vastly reduced, revealing a crisp high-end I didn't notice before. With the extreme frequencies out of the way, I can detect a new separation and clarity of midrange frequencies. Presence is comparable to my LCD3s but with more body.
    So the verdict is: The Lawton TH600 dampening modification provides the tonal balance I wanted to begin with. In my opinion it makes the TH600s world-class headphones. So if you own an unmodified pair of TH600s, you owe it to yourself to install the Lawton dampening modification. It's easy and cheap. I haven't installed the angle pads yet, I will update later if they make a big improvement. Doubt they will help as much as the dampening modification though.
  2. mrscotchguy
    Thanks for doing this write-up. There's not been much info on the TH600s and the Lawton Mods. Hopefully anyone who has/had this configuration can comment on benefits or negatives they've noticed.

    For my setup, I cannot see changing my th600 any, but I am super curious about the Lawton angled pads and if there's any change in sound.

    Please post if you do decide to test the earpad out too!
  3. Sweetmeat
    There is plenty of info out there, but it's spread out over hundreds of pages in the TH600 (and TH900) thread. It's really hard to get a meaningful discussion started in those threads concerning the Lawton mods. I think this is because most guys who own those headphones like them just fine the way they are. When someone mentions Lawton, it is sometimes interpreted as headphone bashing, and met with negative responses. But not always.
    I have learned that some feel the mods increase the treble excessively, although that has not been my experience with my Burson amp and Sabre DAC.
  4. katulu
    I'll be curious to hear your view on the Lawton angle pads. In my TH900s they KILLED the subbass. Not for me.
  5. Sweetmeat
  6. Sweetmeat
    A month ago, I converted my TH600 into the most beautiful pair of headphones in the world (IMHO). I installed a pair of Lawton chambers (Asian Camphor Burl). I was totally unprepared for the transformation of my TH600 from mere utility to a stunning work of art.
    I was already satisfied with the sound of my TH600 upgraded with the basic Lawton dampening modifications. I also purchased the Lawton angle pads. The ear holes looked smaller, so I tried test-fitting them before installation. My ears would be constantly touching the pads during play, so I decided not to install them.
    I omitted the pads but kept the dampening modifications described in the first post of this thread. During my earlier communications with Mark Lawton, he recommended the chambers. After hearing what he did with the dampening modifications, I gained a new respect for the capability of the TH600. I now believe these headphones are truly worthy of such an expenditure.
    Yes, the chambers can be very expensive. It is difficult to justify spending so much on a pair of "economy" headphones. But Mark has a range of prices as well as in-stock specials. It is possible to purchase a pair of chambers for as little as $350. I have found that even the least expensive pair of chambers will totally transform your TH600.
    I purchased the instrument-grade Asian Camphor Burls. Pictures do not do justice to the exquisite color, finish, and fit of these chambers. This wood has an unusual aromatic quality. Mark says it smells like cinnamon but I think it smells more like Ben-Gay. The scent is strong enough to be smelled on my hair an hour after I've stopped using the TH600.
    The Camphor Burls are a Type 2 on the Lawton tone wheel. I think the tone wheel is sort of confusing, because it describes "feelings" I can't relate with. More importantly, the lightest, softest woods are Type 1 and the heaviest, hardest woods are Type 5. Type 1 is most bass, Type 5 is most treble, but the difference is not that much.
    The chambers come with the Lawton dampening pad already installed. The chambers are easy to install, since the basic dampening modifications were already installed on my TH600. Strangely, they install using the same machine screws supplied with the TH600. I was impressed by the exact sizing of the chambers and precise location of screw holes. The fit was perfect.
    So how do they sound? The difference is more subtle than the difference from my last modification. Compared to the dampened metal chambers, the Lawton chambers increased midrange and treble 1-2 dB. Bass slam is about equal, although perceived bass is slightly less. I believe this is due to less sympathetic vibration from the higher mass chambers.
    At home on my high-resolution rig, the high end can be a bit much on some recordings, causing my ears to sizzle a bit. However, at work on my low-resolution rig, the increased treble hits the spot. In both places, the midrange has more dynamics and separation, improving the so-called "layering effect" that sounds so great with vocals and mellotron.
    So a word of warning, avoid combinations of Type 5 woods with highly resolving rigs. However in my experience, the additional treble is restorative if the music has gone through your computer processor. There are additional modifications such as felt rings, that you can apply to reduce the treble. To be safe I would stick with Type 1 or 2 woods.
    In spite of the treble issue, I would highly recommend installing a pair of Lawton chambers on your TH600. These chambers are so unique and sexy, it is worth buying a TH600 just to have a platform for the chambers. For a true headphone lover, they are too cool to pass up.

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