[Packdemon]

If anyone wants to tighten up the bass / dynamics a bit on their HP 150 or 100, here's a method that I call an "external mod", that can be done without any alterations to the headphone itself. Just get 1-2 of these external resistors to stack in front of your headphones, which adds 75 ohms of impedance. Lyova & I have done extensive testing on these, and it seems to tighten up the loose / 'flabby' bass and the dynamics a bit.

https://www.amazon.com/dp/B00A2QJL0C
http://www.ebay.com/itm/272165203681

Also an external "inline volume limiter" can be used for the same effect. The difference is more subtle rather than 'day & night', and is good for either normal or modded headphone, but I would still recommend the modded version from Tru-Fi speakers (link in my signature). Especially the newest revision for his HP-150 mod - it's a sure shot winner and I liked it even about 30% better than his HP-100 mod

DecentLevi

My perception of audio is not quite as great as yours, so I can't say I heard a 30% improvement in dynamics like you did. But, I've always been using impedance (resistor) cables with cheaper headphones that have lower resistance to make up for any channel imbalances (by decreasing the proportion of the difference in impedance to the overall impedance between the two drivers). I'm glad you were there to try that for me though since I, unfortunately, forgot to measure (while I was at the meet) the modified HP150 with and without the resistor cables to see if it made an improvement in the total harmonic distortion ratings (this distortion can be affected by the dynamics of the headphones). So I'm not sure if there is a scientific basis for all this (since I have no personal measurements) other than what I already know about audio (THD, dynamics, electrical impedance, etc.) in general and what Levi told me he heard.

The only reason I prefer resistance cables (/impedance adapters) though over analogue volume limiters, is that analogue volume limiters all tend to have a slight channel imbalance at lower volume levels.

Best Regards,
Lyova Margaryan of Tru-Fi Speakers

 

[7keys]

Another interesting thing about this headphone are the holes around the driver. All the reviews say it is a closed can with one tiny hole....the bass port. actually there are four compartments around the driver, each compartment has five holes. I've found that covering these holes is another opportunity for modding this headphone.
 

 

[Mr Trev]

  Another interesting thing about this headphone are the holes around the driver. All the reviews say it is a closed can with one tiny hole....the bass port. actually there are four compartments around the driver, each compartment has five holes. I've found that covering these holes is another opportunity for modding this headphone.
 

Noticed that while I was stripping mine down. I think (speculation, of course) that's what give these phones a larger than usual SS. Back wave of the driver reflecting forward or something like that

 

[Packdemon]

  Another interesting thing about this headphone are the holes around the driver. All the reviews say it is a closed can with one tiny hole....the bass port. actually there are four compartments around the driver, each compartment has five holes. I've found that covering these holes is another opportunity for modding this headphone.
 

 
Those holes are necessary for drivers to breath. It doesn't affect the sealing of the headphones too much since it is really just the air circulating between the seal from the earpads and the inside of the driver. Most dynamic drivers in closed headphones have them actually (filtered with mesh or felt though). That being said though, there are actually more holes in this headphones from which sound leaks than just the single bass port on each side (or the not so well isolated stock earpads). Air actually leaks inside (and out) from the lip where the earpads are placed, the larger open hole from the hinge port, and the smaller open hole from the hinge port that has the right channel wire/cable running through it.
 
Beyerdynamic "closed" driver:

 
Lip:

 
Bass port (that you mentioned):

 
Large hole hinge port:

 
Smaller hole hinge port:

 
 
Now after saying all that, I still think that your idea of sealing those holes on the driver's plastic diaphragm is not a bad idea at all if you can somehow manage to balance the sound afterwards. I'd actually not only like to see that done to it, but also have entire inner diaphragm plastic portion (not the driver in the middle itself though) covered in dampening material like your blue tac or some dynamat to help reduce even more of the negative phase reflections from the earcup. That could help to potentially make a dynamic driver sound closer (closer not quite there though) to a planar magnetic driver. Basically, it would solve (or lessen rather) the problem presented in this video in regards to the part about dynamic drivers:
 
 
Best Regards,
Lyova Margaryan of Tru-Fi Speakers

 

[7keys]

I'll be using some of this on the holes, I'll start cutting a piece that will fit the whole area in each compartment.

 

[DecentLevi]

I would recommend covering just 1-2 holes on each bank of holes, for a more balanced result rather than closing off an entire section.
 
-or- adding more holes

 

[7keys]

  I would recommend covering just 1-2 holes on each bank of holes, for a more balanced result rather than closing off an entire section.
 
-or- adding more holes

I thought I'd close all the holes first, if I closed only one it might be too subtle a change for me to notice. I'd like to get a good idea of what this will do first and then I could decide on how many holes I prefer.

 

[anticute]

  I thought I'd close all the holes first, if I closed only one it might be too subtle a change for me to notice. I'd like to get a good idea of what this will do first and then I could decide on how many holes I prefer.

Very interesting, keep us posted on the results!

 

[DecentLevi]

Hey, the same earpads that were tested to pair the best with the HP 100 / 150 mod are on a cheap Massdrop:
https://www.massdrop.com/buy/19011
choose the DT770 premium memory foam option (leather, not velour)
 

This is the right one, although they don't show a photo for this one

 

[DON Navyn]

I currently own ibasso dx80 listening with audio technica 50x and creative aurvana live between both Headphones I prefer CAL but I want to upgrade headphone and my choice is soundmagic hp150
is the Sound quality is good without any amp.
how does the Soundstage of hp150 will compete with CAL in term of both width and depth

 

[7keys]

  Hey, the same earpads that were tested to pair the best with the HP 100 / 150 mod are on a cheap Massdrop:
https://www.massdrop.com/buy/19011
choose the DT770 premium memory foam option (leather, not velour)
 

This is the right one, although they don't show a photo for this one

Could you point me to the thread or site where they tested pads for the HP150.

 

[DecentLevi]

  Could you point me to the thread or site where they tested pads for the HP150.

Just click the link at the bottom of my post where it says "HP 100 mod", which says a bit about these earpads of the SoundMagics. I think Lyova (@Packdemon ) has tried multiple earpads though, so probably he can compare them better than I could. I've only compared the original pleather earpads to those Dekoni earpads as pictured, and the difference was an obvious improvement in bass definition and soundstage, IIRC.
 
So how were the results of your experiment with the holes in the plastic?

 

[7keys]

 

  Could you point me to the thread or site where they tested pads for the HP150.

Just click the link at the bottom of my post where it says "HP 100 mod", which says a bit about these earpads of the SoundMagics. I think Lyova (@Packdemon ) has tried multiple earpads though, so probably he can compare them better than I could. I've only compared the original pleather earpads to those Dekoni earpads as pictured, and the difference was an obvious improvement in bass definition and soundstage, IIRC.
 
So how were the results of your experiment with the holes in the plastic?

What about comfort, I found that after an hour or so the SoundMagic pads pinch my ears.
 
I haven't had time for more modding of the HP150. I hope I can get around to it this week.

 

[DecentLevi]

The Dekoni pads have immaculate comfort and can get a great seal, and seem to 'disappear' after a while. They are also thicker than stock pads, so your ears aren't likely to touch the drivers, and I haven't noticed any pinching effect.
 
You can also adjust the bass refinement according to the method of applying these earpads: either in the lip or around the lip of the headphone

 

[7keys]

I made a pattern and cut out eight pieces of foam that would fit nicely into each compartment around the driver of the HP150. It seems to have an interesting effect on the sound. To my ears the HP150 could be a bit piercing at times, this is gone. The treble is subdued; it’s there but doesn’t stand out. It now seems to have a mid-bass hump, the sound is thick. It has a dark chocolaty tone with a rich gooey center; an audio malomar………… is what I’m describing. When I first put it on I thought it sounded like a M50X with a little more mid bass hump, less treble and a better soundstage. Not really what I’m after but it’s fun to listen to. I get the impression that if you knew what you were doing, I don’t, you could tune the sound into whatever you wanted.

I wish I had the equipment to measure these after each mod.
Next I think I’ll try to open up two holes in each compartment while leaving the foam in place.