Howdy my Head-Fi brethren.
I have been playing around with the HD25-1 for quite a while as I use them all the time for listening to music and ebooks in the day and DJing at night. The only thing then I dislike about them is that the bass is lacking a little detail so I decided to start trying some mods to squeeze a bit more out of them. These mods would work on the whole HD25 range as they all have the same basic design. I can not take all the credit as Armaegis and Jamie Chisholme were kind enough to help me with a lot of testing and ideas.
I am not saying that all or any of these mods are the best way of doing it and would love to hear anything anyone else you has tried.
Most of the mods are cheap and easy to do and if you have any questions just ask
I will start off with the easiest one..
I replaced the felt disc of damping material with some rattlematt ( a bituminous vibration damper ) stuck to the inside of the earcup. This seemed to tighten the bass a little and make them sound a little more open. I suppose it is probably a bit like giving the driver a slightly larger enclosure as the rattlemat takes up less volume and absorbs more of the energy coming from the back of the driver.
If you need help popping them open check out this thread http://www.head-fi.org/t/571128/dismantling-guide-for-the-hd25-1
Next I tried a little mass loading
On the back of the driver enclosure I have stuck some 6mm window lead strips around the central pillar This adds a bit of mass and partially blocks the bass ports behind the magnet. Mass loading is a a way of making sure more energy goes into the ear rather than going into shaking the enclosure ( it's entirely newtons fault for creating his third law ) I have also added a bit of rattlematt to the back as well.
I also pit a strip of 6mm lead round the outside of the diaphragm enclosure 6mm will fit perfectly. Then added a layer of rattlematt over that as well. In the picture I have peeled back the two layers at the end so you can see them.
If you try taking the grill off like in the picture above be super careful not to touch the voice coil wires as they are very delicate and a nightmare to repair. The grill just pops out - easiest way is to grab one of the spokes with some pliers and lift it out.
I removed the disc of foam inside the pad and put the pads them selves through the washing machine which is supposed to soften them up a little and make long periods of use more comfortable
This next one is a little silly but while I was at it I thought I would 24ct gold plate the springs inside the socket and some cardas HPSC connectors to match. One of the thins that tend to go wrong with the HD25 is that the springs build up oxidisation which causes a bad connection so I thought gold plating would fix that and give a better connection. I gold plated the tips of the HPSC connectors as I got a bit carried away bit it can't hurt.
To getting the springs out is extremely dangerous but if you must... you have to remove the little white plastic cap over the inside of the driver making sure to move the voice coil wires out of the way first
Then I made my self an SPC cable and wrapped it in para cord so it was not to microphonic - the HPSC connectors are a bit fiddly to solder but there is quite a lot of help on the DIY cable thread http://www.head-fi.org/t/71148/diy-cable-gallery.
I sent a few cables out to people to try and the results were inconclusive with some people saying that the SPC sounded better than the standard steel and some did not noticing any difference. The SPC certainly has lower resistance so is a little louder and I think it gave a little mre detail but it may be a placebo.
As they were going to be my own personal pair I made a few cosmetic changes with 23.5ct gold leaf and lacquer. The lacquer will add a little extra rigidity but mainly there to give a nice shiny finish and protect the gold. You can pick up a gilding kit quite cheaply online and it gives a lovely finish.
Edited by jfunk - 3/29/12 at 1:38pm