Introduction: Grado SR-325 Mod Using the Sennheiser HD-570 Headband
Basically I'm using my Grado SR-325 and modifying it to fit another headphone band, the Sennheiser HD-570.
Well the Grado headband was wearing out and never has fit well on my head. It is also so flimsy. I really dislike the fact that the cans rotate and the cord gets all tangled up. Also I would constantly have to readjust the fit every time I put the headphones on. I added some silicone tubing to help fix that problem which you will see pictures of later.
Recently the sound on the left side would cut out intermittently. Probably due to the spinning of the earpiece over time. I have to repair the wire anyway so I started thinking about modifying these headphones. I prefer a headphone that has only one wire attached to one can so I really wanted to rewire it that way. I have had the Sennheiser HD-570 for years and have never liked the sound but have always found it extremely comfortable so why not merge them together and have the best of both worlds.
I've also changed the original ear pads that were falling apart using the Sennheiser H-19545 Foam Earpads that are for HD 414 Headphones. I like the yellow color. Currently B&H are selling them at the cheapest price I've found. Much cheaper than buying replacement Grado pads. I won't be showing how to do that as there are plenty of resources out there for that. It's extremely easy anyway. You just cut a smaller hole than the earpiece and put them on backwards.
I really didn't plan this to be an Instructable. I really only took some pictures so I would remember how some of the pieces looked before I made major changes. After I was about half way did I think this might be a good Instructable.
Hopefully it will turn out good - The Instructable I mean. I already know how the headphone mod turned out :)
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This project came together quite nicely and only took a couple of evenings to get most of it done. Be sure you are prepared to ruin a perfectly nice pair of headphones before you attempt this. I amnot responsible for you ruining an expensive pair of headphones. Attempt at your own risk.
---Ok lets get started ---
Tools you'll need are :
Very small flat head screw driver
Phillips head screw driver
Soldering iron and solder
Gloves - a must when holding hot parts
Hot glue gun
Heat gun or hair dryer to soften glue
Drill and a bit
X-ACTO knife or razor blade
Metal file and/or a dremel tool
220 grit sandpaper
Band aids... Oh wait, that was for me. Lets hope you won't need them.
Gently pry the ear pads off the Sennheiser HD 570. There should be some screws to remove using a Phillips head driver. Now try and remove the plastic casing on the backside. Slide a small flat head in there to pry it off. I didn't take pictures of this process or the teardown of the Grado unfortunately.
You should see a small angled plug attached to the driver. Unplug it and remove the ear piece from where it swivels. You could just snip the wire with some cutters if you wish. The left side will have the stereo plug. Leave intact. Remember which is the left channel and which is the right channel. Also at this time you should mark which wire is positive and which is negative.
Now both earpieces should be removed from the HD-570. Lets move on to the Grado.
My first little mod came in the form of a piece of silicone tubing. I got tired of the earpiece drooping down and not keeping the cans at ear level which meant I had to readjust the fit every time I put these headphones on. I just cut it to size and popped off the plastic end cap and slipped them on the little antenna looking things. That sure made wearing these headphones much better. Any local hobby store will have it. But we are getting rid of them along with the head band for a much better design in my opinion.
It's easy to separate the cans from the head band. Just remove the plastic end cap on the antenna thing and slide them off. If you can't get it off just use a pair of pliers or you can slice it off with a box cutter or X-ACTO blade. Careful! Remember to cut away from yourself.
Next just spread the plastic bracket that is around the metal can and slide them off. You should cut the wire from the headphones just to get it out of the way. You should have also removed the ear pad.
Now to separate the driver from the can surround which is one of the hardest parts of this project.
Time to use that heat gun. We have to heat the earpiece to soften the glue that is holding the plastic parts which also contain the driver (speaker). You will need some gloves so you don't burn yourself. Make sure you heat the aluminum and just hot enough to soften the glue to ease the plastic ring, screen, and the main head phone driver. While you have your gloves on just push on the screen to slide the whole thing out. The screen is of high quality and thickness and can take the pressure of your thumb. Just use more heat if it cools down to quickly. Even heat is best so don't stay too long on one area.
I went ahead and removed the SR 325 buttons on the screen. That was very hard to get all that glue off the screen. I put it in the fireplace and let it burn off but don't let it get red hot. Now just let it cool down and use a wire brush to clean it off. Now the screen is bare metal and I like the look of it.
Try and get rid of the excess glue around all the plastic areas. Using a fingernail and X-acto blade help here. To remove the glue from the aluminum can just heat it again and then wipe off with a paper towel. Don't sand it off. I did use a screw driver to lightly scrape around the corners while the aluminum was hot. Remember how it all came out so you can assemble it back. These pictures should help but yours might be a little different.
Ok, now we need to measure the width of the shaft so it can fit on the aluminum can. I put marks on the picture that you need to measure between since this is the area where the Grado aluminum cans will rest on.
Choose a drill bit that is the same width or slightly larger. I used a 3/16 bit which was just slightly larger than my measurement. Yours may be different. I used a drill press so that made it much easier for me. If you use a hand drill it may be best to start with a smaller bit that is just slightly bigger than the original hole. Use the next size bit and so on till you get to your final bit. This is a nice piece of aluminum so you don't want to mess up.
Now mark the width of the shaft from the Sennheiser. We need to remove the aluminum between the marks so the shaft can slide in.
Use a file or a dremel tool which I used. You must clean it up with some sand paper. 220 grit works well. A file will take some time. Maybe you could use a hacksaw then file it smooth. We don't want any burrs to cut into the plastic shaft that will fit in there.
Once you are done be sure and fit the Sennheiser shafts in place to make sure it fits. Don't worry if the both shafts don't match up to fit in the can at the same time. That will be covered in the next step. We just want to be sure the shafts will be able to fit easily and not bind. If it does you may need to file it down more or enlarge the hole just a bit. It is imperative that all surfaces are smooth.
Go ahead and insert the screen in the position you want it in then hot glue on top and slide the plastic ring on top of it. Don't go crazy with the hot glue. Only use it sparingly.
Now see if the shaft fits. It doesn't? If yours is too wide like mine you'll need to melt one side to bring it in to fit. It didn't take much. Only needed about an 1/8 of an inch or so. The plastic is thick and holding a soldering iron under it took too long so I used a lighter. Yes you can clearly see where I heated it up but it doesn't show too bad. Try and even out the heat you apply so you don't catch it on fire. Do not had the flame near the wires.
Now the stereo plug needs to fit in the original slot that the Grado wires came out of on the left aluminum can. Actually it doesn't matter which one you use right or left because they are identical. Just know that the one you use will become the left side. I used the dremel to remove some of the plastic and then finished it up with the Xacto blade. Don't remove too much. You want it to fit snug and not loose.
Almost done now. We need to make larger slots on the plastic driver casing. I just used a dremel to widen. Don't make it deeper than it already is. Only widen the sides that will align with the Sennheiser shafts. On the left side you must also enlarge for the stereo plug to fit.
Time to solder. This was extremely difficult for me. The wire is very thin and has a coating. You have to remove a lot of nylon that is twisted around the wire. Just use some 220 grit or finer sandpaper to shine the wire up. Do it very lightly because the wire is fragile.
Be sure and test to make sure the connections are actually working before you add hot glue to help stabilize it. Now when I actually finished everything and hot glued it all up and thought I was done. I plugged it in to some music and... well... It sounded funny. It was out of phase. One of the drivers was wired incorrectly. Whoops!
So I had to find out which side is miss-wired. Try and find a mono sound source or tone generator. Listen carefully. The louder speaker is the correctly wired one. The weaker sounding one is the one we need to switch the wires on. Better to figure this out now than to have to take it apart and rewire it like I had to.
The finished product.
I hope you enjoyed seeing part of the process. I really like how it turned out. My white paint job on the letters isn't so good. I'll need to redo that in the future. When I started listening to it again it really felt too tight so I heated up the plastic where it is adjustable and stretched it out a bit on both sides to make it even. Now it fits just right.
Some may question why I would remove the Grado wiring to something much thinner. Well I'm not much of an audiophile and can't hear any difference except now the left side no longer cuts out and I can easily replace the cord now.
My ears can't tell the difference but the new modification fits my head better and I no longer have to constantly adjust it to fit properly. I am very happy with this project and I hope it inspires you to take a look at the possibilities.