[randomprecision]

Hi all.

I apologize in advance if this has been covered extensively (and it probably has been). I did try searching for it but the results were spotty.

I've seen a lot of discussion about the blu tak mod making a dramatic difference on closed cans. But I haven't seen much discussion about using it on open cans.

So I was curious. I have a pair of Sennheiser HD 497s. Now these sounded decent right out of the box (They're ugly and somewhat uncomfortable but they sounded OK). So I got myself a few packs of poster adhesive and went to work on them.

I noticed initially that even though they're quite open, if I placed a finger on the enclosures or the headband, I could easily feel vibrations.

When I took them apart, I was gratified to find these are very easy to work with. The cables completely detach so you don't have to worry about ripping them out. I put the putty (I'll just call it putty because it isn't actually brand name Blu Tak) on just about everything inside that could vibrate and cause the enclosures to muddy up the sound.

I did hear a difference at first but not as much as I expected. I messed around with it and experimented and did a lot of listening. I kept working with them until I could only barely feel any vibrations at all even on the loudest portions of music (not as easy as it sounds). I left the parts of the enclosures that have holes alone because even though those parts do vibrate as well, they serve to keep things ventilated and it's very difficult and time consuming to work putty around all these holes (look up a picture of the HD 497 to see how many holes there are on the earcups).

When I finally got it right, I was astonished! It seriously cleaned up the sound! I was amazed how much the enclosures and the headband (I put some putty in little recesses in the headband where you can't see it too) were screwing with the sound. Even with them being open cans, the mod makes a world of difference.

My conclusion is that anything that vibrates will benefit from damping. If the drivers are attached to thin plastic that vibrates, this will affect the sound. Even if the cans are open. I wouldn't say they sound as good as much more expensive cans but I bet they're at least 80% there.

Anyone else try this mod with open cans and experience positive (or negative) results?

 

[4saken]

You could have used "audiophile approved" Dynamat (works like heavy blue tak), though I'd imagine covering the entire cup and the driver would make it very heavy (and hence uncomfortable)

EDIT: Oh, and something along the lines of this is achieved in markl's D5000 mod, however it is all internal since the Denon's are closed cans.

 

[randomprecision]

Well, I found that the poster tak works well enough. Although Dynamat may very well be more effective. I did find that all the excessive vibration is very hard to get rid of and the bass is still just a tiny bit muddy in spite of it all. This could simply be a driver issue but I think there is still enough vibration to case some distortion so I will probably continue to experiment.

 

[b0dhi]

On top of the putty on the inside of the enclosure, place a layer of damping felt about 3mm thick. That will clear up the muddiness in the bass significantly. On the downside, though, the bass volume will be reduced.

 

[dcpoor]

can you take some pics of your blu tak mod?

 

[randomprecision]

I wish I'd thought of the felt thing before I put them back together.

On the pics, I will probably take some pics next time I take them apart. Unfortunately, when I put them back together this time, I had to painstakingly cut out little squares of paper towel to fit because I put putty on the outside of the driver housing where the pleather sits. Otherwise, the pleather on the cushions would adhere to it and would tear it. So the screw holes are covered now. I'll have to wait until I have more timeso I can reassemble them properly.

They're sounding great, if a little fatiguing. A certain amount of honkiness. Not sure what's causing that.

 

[darkswordsman17]

I'll be honest, I don't think the majority of the sound change in the blu-tak mod comes from the tak (in fact, I tested a lot versus much less and didn't notice much if any noticeable difference on even closed cans). The major change comes from putting something that actually dampens the back of the driver (I just use cotton since it's cheap and easy to work with and does the job well).

It's kinda funny, as I was just thinking the same thing, that there's no reason the blu tak mod can't work on every headphone, there's no reason it couldn't work on open ones as well. I don't have any, so I couldn't test out my theory. I wonder if some headphones that people find lacking in bass can't be adjusted to bring out a little more quantity with little expense to quality (K701 and DT880 in particular I was thinking about).

I've also discovered something else, although I don't know if its just this model or might carryover to others. On my A900Ti, if I dampen directly behind the driver, it brings out certain parts of the sound (guitars in particular REALLY come out). If you dampen the outer edges (not directly behind the driver itself but the outer ring that blocks the sound from bouncing back to your ear), it impacts the bass and vocals more (dampen a lot and vocals are more pronounced, dampen less and bass is). Not sure if it would be the same on open ones or not. Certainly either extreme (heavy dampening or none at all) tends to completely ruin the sound, so you want to find a nice middle ground. In my own personal experience, the dampening done stock on many closed headphones seems to be pointless or actually harm the sound more than help.

Lastly, and I just thought of it, is I wonder what would happen if they made a closed headphone that didn't have the outer ring (so the sound could bounce off and get to your ears)? I don't really want to punch through the material that is there normally to find out. Taking that idea a step further and actually face the driver away from your ear, so that you only get the diffused sound (kinda like Mirage employs in some of their speakers). I think that'd sound interesting. Probably not good for music, but might be good for movies. Or maybe to make a surround headphone, have two drivers back to back (with each one ported to a different side so they don't influence each other that way).

Oh, and one last thing, as its a popular part of the Denon mods, is that also firming up the earpads impacts the bass. Again, I think you'll want to aim for a balance, as if you really stuff them it does three things: pushes the driver farther from the ear, increases the enclosure area, and also seals it better. Combine the 3 and, at least in my experience you get quantity over quality (so boomy, kinda slowish, not well articulated bass). If you don't do any at all, you might end up with a brighter more in your face sound (which hurts my ears).

Ah, and one other final thing is the material between your ear and the driver. I think you definitely want some material there, but you want it to be fairly thin and I'd say cloth is probably better than foam. The nice thing about all of these is that it allows you to tweak the sound to something that might suit you better. Generally it won't completely change the character of the drivers, but it likely can alter it enough to better suit your tastes. In many cases, I think a good solid amp will accomplish much the same thing (as long as the sound of the amp is the same as what the mods would adjust in it).

Wow, sorry to get so wordy.

 

[DemonicLemming]

Quote:

Originally Posted by 4saken /img/forum/go_quote.gif You could have used "audiophile approved" Dynamat (works like heavy blue tak), though I'd imagine covering the entire cup and the driver would make it very heavy (and hence uncomfortable) EDIT: Oh, and something along the lines of this is achieved in markl's D5000 mod, however it is all internal since the Denon's are closed cans.

Dynamat is absolute garbage. There are other companies - elemental Designs, Brown Bread, B-Quiet, etc, that make damping solution materials that are much, much, much better and less expensive.

Dynamat is viewed in the car audio world like Bose is looked at in the musical world.

 

[randomprecision]

Hey. Thanks for the responses guys!

And yeah. Like I said. I don't see why the blu tak can't help on most headphones. Open or closed. Like I said, if the earcups vibrate, that has to translate into sound. And I kind of doubt the earcups themselves are actually designed to function as part of the mechanical system.

My theory is that you can only benefit from isolating the drivers as much as possible. My ideal, I think, would be earcups that don't vibrate (or resonate?) at all.

I could be wrong but I think there's a couple of different kinds of damping that serve different functions. I don't think foam or poly can prevent the earcups from vibrating. That physical connection the drivers have to the plastic will radiate out through the cheap plastic many headphones are made of. I noticed (before I started with the putty) that even if I placed a finger on the headband at the very top of my head, I could feel the vibrations. I'm thinking if the vibrations from one earcup can travel all the way to the other one, that can't be good for the sound.

I think anything that tames this can only clean up the sound a bit more. The HD497s have a very basic, cheap, plastic headband. Right now, I'm looking for ways to keep it from resonating. Basically, I want to get as close as I can to physically decoupling the earcups from one another (while still keeping my headband and not doing anything permanent, of course).

The foam and other such methods, I believe, are more to prevent reflections and keep sound from bouncing around inside the earcups. So a perfect balance is probably a combination of these techniques.

But you have to be careful with the polyfill/felt/foam (in my experience anyway). It doesn't always seem to have the desired effect. Sometimes it does something to the sound that I can only describe as "wrong". At least it's easily reversible, though.

And again, as these are open cans, I don't want to block the airflow. Sennheiser seems to have made quite a few models on the basic bones of these cans. Some are open and some closed but I believe they all use essentially the same drivers. I had a pair of the closed ones and they didn't sound anywhere near as good as these 497s. I did not, however, try the blu tak mod on them (I hadn't discovered Head-Fi when I had them).

Most of the putty I was able to put inside the 497s is on the back of the driver and the thin plastic part it's attached to. I worked around the holes on the back of the driver itself. And actually, yes. The amount of putty used did seem to make a difference.

But the biggest difference, I admit, comes from covering as much plastic as you possibly can with the putty. That's where I found the real difference. Just putting dots of putty here and there makes a minor difference. But smooshing the putty into every nook and cranny and covering as much of that resonant thin plastic as humanly possible makes a BIG difference. It just tightens everything up and really brings out fine detail.

This, I think (probably) is where Grados excel. The whole design of the Grado cans (even though most are made of plastic) seems to be intended to resist vibration. Admittedly, I have not (yet) tried a set of Grados but I think the basic shape of the earcups is revelatory.

Lastly, I did remove the cloth that was on them when I bought them. I also removed the drivers and drilled out the holes in front of the drivers to a larger diameter (Unfortunately, on one side, I messed up a little and drilled a few holes too large and took a chunk out of the plastic but it doesn't seem to affect the sound). I'm thinking of trying it with the cloth put back on. Fortunately, I have a couple extras of those rings that the cloth is attached to from another very similar pair of Sennheisers.

Anyway. It really is amazing. I think everyone who likes to tinker could benefit from buying cheap pairs of headphones and tinkering around with them. It's amazing how good they can sound if you can mitigate some of their basic design flaws. The drivers in these will obviously never be as good as the drivers in some of the more expensive cans but they were pretty good to start with. And they have good sensitivity so I can play them directly out of my sound card with no problems at all.

On the issue of weight. I don't know. I don't mind heavier cans, really. As long as I know that weight is doing something useful. What bothers me more is the clamping pressure inherent to this design that dits directly on your ears. Ouch! I'm looking at getting a set of Grado SR80s in a couple of months. If they're as good as they're said to be, I may not buy any more headphones for a while.

 

[randomprecision]

Quote:

Originally Posted by DemonicLemming /img/forum/go_quote.gif Dynamat is absolute garbage. There are other companies - elemental Designs, Brown Bread, B-Quiet, etc, that make damping solution materials that are much, much, much better and less expensive. Dynamat is viewed in the car audio world like Bose is looked at in the musical world.

What are the differences? I'm genuinely curious. Not being argumentative. I know Dynamat is very expensive for what it is. I just don't know what's better about the other ones (other than cost). It would be nice to know so I know what characteristics to look for. There are quite a few applications for this stuff other than audio.

 

[DemonicLemming]

Quote:

Originally Posted by randomprecision /img/forum/go_quote.gif What are the differences? I'm genuinely curious. Not being argumentative. I know Dynamat is very expensive for what it is. I just don't know what's better about the other ones (other than cost). It would be nice to know so I know what characteristics to look for. There are quite a few applications for this stuff other than audio.

Adhesive quality, backing quality, thickness, actual damping ability, price, how long it'll actually stay where you put it (which is important cars due to heat retention in the summer), how easy or hard it is to get, smell, etc.

Dynamat Extreme is, granted, decent, but the original stuff is junk, and all iterations of Dynamat are ungodly overpriced.

I know B-Quiet is good stuff, and the eDead stuff from elemental Designs is also supposed to be good. MMat is another that was ranked highly when I was in car audio, as was Brown Bread. You've also got sheet and liquid versions of damping material - not sure how well the liquid would work for headphone applications, but it was great for filling voids that were inaccessible if you wanted to use the standard sheet stuff. Stopping vibration without stopping resonance (varied reasons for that in car audio), people would normally buy non-expanding foam (sort of like Great Stuff, the kind that comes in a can). A lot of trunk lids got filled with that non-expanding foam, as acting only as something to stop vibrations, it worked well. It simply didn't have the density required to really cut resonance, backwaves, etc.

 

[OutdoorXplorer]

i can't remember where i saw a website that show how to apply bluetak to the grado driver. mind show me there ...?

 

[randomprecision]

Quote:

Originally Posted by OutdoorXplorer /img/forum/go_quote.gif i can't remember where i saw a website that show how to apply bluetak to the grado driver. mind show me there ...?

I have no idea what the site is but really. It shouldn't be difficult to do. You would only have to play around with it and experiment to achieve the desired results. It's not like you can't remove it if you don't like it. Just exercise common sense. Be careful around the areas where the wires attach and don't get any on the membrane of the driver. Of course, I'd be more hesitant to do anything to the more expensive Grados simply because the slightest mistake (no matter how unlikely) could screw something up. That would be a very expensive mistake!

 

[TMM]

Quote:

Originally Posted by DemonicLemming /img/forum/go_quote.gif Dynamat is absolute garbage. There are other companies - elemental Designs, Brown Bread, B-Quiet, etc, that make damping solution materials that are much, much, much better and less expensive. Dynamat is viewed in the car audio world like Bose is looked at in the musical world.

I find your comment hilarious given that it is a mass loading product. All it has to do is be heavy, and be convenient to install (i.e. stick to a surface well) of which it does both brilliantly. It's only purpose is to increase the mass and thus reduce the resonant frequency of the surface it is applied to ... it's not rocket science. If you glued rocks to the inside of a car door it would work just as well, but would be a pain in the arse to do.

Also Dynamat isn't viewed like Bose in the Car Audio community, because i haven't heard of anyone who doesn't like it. Unless theres some super elite car audio group that hates it that i don't know about? It's not overpriced on ebay btw

And resonances aren't always bad. I applied some blutack to the metal on the back of my A900 drivers and didn't like the result - the treble became distant, dull and boring.

 

[tfarney]

Quote:

Dynamat is viewed in the car audio world like Bose is looked at in the musical world.

Good to see you make that distinction between car audio and music.

Tim