A resistor adapter is simply a small adapter between an MP3 player and headphones that has a resistor on each of the sound channels. The reason for this is to increase the resistance of the headphones, forcing the MP3 player to work harder to drive them. Many players (with the Cowon D2 being the most known player with this issue due to its powerful amp) can’t perform well with low impedance headphones such as lightweight 32 ohm headphones or earphones that can go as low as 16 ohm. Beside the issue with the volume control not being sensitive enough to work well at volume levels as low as you might get in such cases, the amplifier in the player simply can’t perform as it should under such low loads.  This issue, called roll-off, mostly affects bass and the effect can be seen very easily in this RMAA graph (courtesy of elektrokrishna.com).

As you can see, the bass frequencies are seriously compromised at 16 ohm load (left side of the graph – it should be flat). At 80 ohm it’s a lot better, but only at 300 ohm is it really as flat as it should be (technically lower than that but there’s nothing showing a load between 80 and 300 int hat graph). This issue is fixed by simply adding a resistor adapter in between the player and the headphones, upping the load on the player and giving you better sound quality (a lot more bass in this case) – granted your player has a roll-off problem.

Tutorial

First off you need to gather parts. You need two identical resistors, and by that I mean IDENTICAL resistors. Two resistors that are said to be 40 ohm, might as well be 38 and 42 ohm, so I urge you to use a multimeter and measure the resistors until you find two that match. As long as they match eachother, it will be fine. Depending on your headphones and their impedance, you need to balance the added impedance versus the loss in battery life (don’t panic; higher volume level caused by the harder-to-drive headphones means a slight loss in battery life, obviously) and the fact you still need to be able to turn the volume up high enough for you to hear (so no 1 kohm resistors, people). I usually recommend about 40-50 ohm for 32 ohm headphones, as 80 ohm is a nice level – even if it doesn’t make the curve above completely flat. If you have a D2 or another player with a powerful amp, you could easily do 100 ohm for the adapter. The parts used aren’t exactly that expensive (not if you buy in bulk, anyways, one by one they might be) so why not make several to experiment?

When you have your resistors, you also need a short wire, a female 3.5mm (1/8″) headphone jack, a male 3.5mm headphone jack, some wide heatshrink, a hot glue gun and a soldering iron (the picture shows two of everything since I made two adapters while taking the pics, a custom cable job for a buyer – see the “custom cables” link at the top!). Of course this is what I used in this particular tutorial, as with all tutorials I do I can’t show you every single design you can do for a resistor adapter, I can only show you one and then you have to take the methods I use and implement them on your own adapter. In other words, you don’t need to match the parts perfectly with what I use. For example, this tutorials shows how to make an angled adapter – you might want a straight one, or one with a short extension cord- etc.

For the 3.5mm male headphone jack, I do recommend the ones I use here – they are simply old earphone plugs split open and stripped to the bare plug. These are excellent low profile plugs and far better than the DIY ones you get at “The Shack” because they are small and cheap. You can also get these from cheap audio cables sold at DealExtreme.

First off, solder the wire to the ground channel of your 3.5mm female jack. On a male 3.5 mm jack, the ground channel is the root of the plug, the right channel the middle of the plug, and the left channel the tip of the plug. You have to extrapolate this to the female jack to see what solder point is what channel. The ground channel is normally in the logical place, but on some connectors – like the ones I use here, the middle solder point of the female jack is actually the left channel and vice versa, as inside the plug there are metal springboard-like connectors that go in opposite direction of the each other, making the channels switch place inside the connector. This can be seen on picture 7 below where you can see inside the connector as the top plate is clear plastic. Bottom line: make sure that what you think is the correct solder point for a specific channel actually is just that.

Using the hot glue gun, glue a resistor to each side of the female jack.

Cut the ground channel wire to length and solder it to the ground connector on the male 3.5mm jack like the picture shows.

Hot glue the male 3.5 mm jack to the female 3.5 mm jack, pointing as shown above. Notice the insides of the female connector and how the springboard-connectors make the channels switch place. Your 3.5 mm female jack might be like this, or it might not. You have to find that out or you risk mixing up the channels.

Solder the resistor legs to the male 3.5 mm jack. Again, make sure you match the channels properly – the tip of the male plug is the left channel, which means that the tip of the solder-end of the male jack is also the left channel. Right is in the middle on both as well. Match this with the correct resistor.

Test that it works. You can use this file to check that you got the channels right (or find out which is which on the female connector if you haven’t already). The first 5 seconds of the audio file plays using both channels, the next 5 seconds is left channel only, while the last 5 seconds is right channel only.

Encase the entire thing in hot glue. This insulates against short circuits and makes the whole thing a lot more sturdy. Please don’t skip this step because it looks ugly, your adapter will self-destruct after 5 minutes of use.

To make it a bit better looking, you can use heatshrink. I found that 20 mm (diameter) heatshrink worked well for the two adapters I made here. I recommend getting heatshrink that’s narrower than what you need and then use needle-nose pliers to extend it. That way you get better shrink ratio to better cover the less-than-symmetric adapter you just made.

That’s it, you now have a resistor adapter. If you’d like, you can take a look at the video below. It’s very old, from the first resistor adapter how-to I made. Still, might be useful in some way (though I doubt it).

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The FrankenFiiO (V1-V2 link, V3-V4 link) mods were a series of mods I did to the FiiO E3 $7 headphone amp (black, white) about a year or so ago. It started with some rather ugly, bulky devices and ended with a sleek, wooden amp with it’s own analog volume control – the V4. The V4 was the one the guy in the email wanted to know about, so the schematics and tutorial shows how to wire that setup. However, the box design is more or less the only thing different between the versions, so the basic concept applies no matter what you want to do with it.

Parts needed

Obviousely you’ll need an E3. You’ll also need some wires, a stereo potentiometer designed for audio use (there are a billion different ones so pick one that fits your project), two female 3.5mm (1/8″) audio jack connectors and some wires. You also need some way of turning the thing on and off – the default way of turning an E3 on and off is to insert a headphone plug in the headphone port. A method that is even less usable when you’re going to rewire everything. You can therefor either buy a power button, or get a stereo potentiometer with a built in on/off feature. These work by having a on/off clickswitch when you turn the volume all the way down (these are very common in cheap portable radios etc so you’ve probably used one and know what I’m talking about). There are also 3.5mm jacks that will do the same as the stock FiiO jack and turn it on when a plug is inserted. Whatever floats your boat. In any case, if you’re not using the stock on/off method, you will also need a 3.5mm male hadphone jack – just cut it off some crappy headphones or acquire one in some way or another.

Wireing

The wireing is pretty simple and straight forward. First off, get rid of the casing so only the PCB (motherboard) is left. The cut-off headphone jack should be inserted into the headphone-out on the E3 PCB (you can cut off as much as you want of what sticks out, but be sure to not short circuit the 3 channels in the jack). This is necessary to have the E3 always be on so that we can wire a new power switch directly from the battery or it wouldn’t work since the E3 would think no headphone was connected and not turn on).

Each end of the E3 PCB has an audio jack. Take notice of which one’s in and out (by looking at the casing). There are basically 3 SEPARATE solder points on each jack – one on top, one in the middle and one at the bottom. On a male 3.5mm jack, the tip is the left channel, the middle is the right channel, and the base/root is the ground channel. When you insert the male plug into a female connector, that is of course flipped so the left channel (that the male tip touches) is farthest from the jack hole. The right channel is still the middle, and the ground channel is closest to the jack hole. It’s important to know where each channel is within the plug, as some female connectors are rather deceiving when it comes to this; the ones I used on my E3 mod had a transparent top plate where you could luckily see that the middle solder point actually was the left channel and vice versa as they switched places inside the connector itself. Point being: make sure you solder the left channel wire to the left channel connector, not just what you THINK is the left channel connector – and so on. The external female connectors shown in the schematics show the internal connectors, not the external, as they vary depending on what connectors you use- so pay attention.

When you have the audio connectors sorted out and know what solder point is the correct channel, the rest is pretty simple. For the input jack, you simply solder a wire each on the left, right and ground channel connectors on the stock E3 audio connector and then solder the wires to the corresponding sodler points on one of your external female audio connectors – as shown in the schematic.

The output jack is a bit more tricky, but it looks more complicated than it is. You basically wire it the same way, but on the way from the stock audio connector on the PCB to the new audio connector the wires have to “stop by” the potentiometer so you can control the output volume. A stereo potentiometer will in most cases have 6 solder points – 8 if it has a built in on/off switch like mine (and the one in the schematic). The 6 ones that are clustered together is what you need to look at first. If you hold the potentiometer with the solder points pointing towards you and the volume knob shaft pointing to your right, then you’ll have a matrix of 2×3 solder points. The bottom two solder points is the audio input for each of the left/right channels, the middle two are the audio outputs for the left/right channels and the top two are the ground pins. As shown in the schematic, you solder a wire from the left channel of the stock female connector on the PCB to the left (or right, but lets keep it clean) bottom solder point on the potentiometer, then a wire from the left middle solder point on the potentiometer and to the corresponding left channel solder point on the new external 3.5mm female audio connector. Then you do the same thing for the left channel. For the ground channel, just solder the wire from the stock connector’s ground channel to BOTH of the top solder points on the potentiometer and then to the ground pin on the external 3.5mm connector (you can do this with one wire if you wish, just removing some insulation in the middle and soldering that to the potentiometer pins. The schematic shows all of this.

The last thing to do is to add the power switch. Solder a wire on each of the battery connectors. One of the wires you connect directly to the battery (make sure you connect to the right end of the battery by looking at how it would sit in the stock battery holder), and the other one you solder to either of the two solder points on your power switch (in my case one of the two remaining pins on the potentiometer). Then you solder a wire from the other solder point on your power switch and to the other end of the battery. As for the battery, it has to be 1.5V – but if possible you should cram as much in there as possible. You can do that in several ways: by using a bigger batter, such as a AA, C or even D battery instead of the AAA, or by connecting several batteries in parallel (NOT series). For example, if you have a flat box that will fit several AAAs but no AA, you can use several AAAs by connecting the positive ends of each batteries to one another and the same with the negative ends (NOT postivie to negative as that will increase the voltage, not capacity). An AAA battery has approximately 1000mAh, an AA battery 2000mAh, a C battery 6000mAh and a D battery 12000mAh, but the actual capacities vary by brand. A crappy AAA can have 500mAh or less and a good D battery can have 20000mAh. If – for example – you used 2 lithium AA batteries with a capacity of about 3000mAh (those fancy expensive Energizer ones) that would give you 10 times the battery life of one crappy AAA battery. You get the point. Cram as much capacity in there as you can, but make sure it’s 1.5V.

That’s it. I explained this in more detail than necessary so here’s the short version: Put a cut-off 3.5mm connector into the input jack to override the built in on/off feature, rewire the audio-input to a new connector, do the same with the audio-output but wire it via a potentiometer. Rewire the battery and add a power switch.

Case

I’m not going to show you how to carve a wooden case like the one I made as it’s one of those things that require skills, not a tutorial. Either you know how to do it, or you’re too inexperienced with the tools needed to do it even if I told you. Amps fit into a variety of things from mint boxes to random plastic storage boxes or tuna cans. Use your imagination

This isn’t a problem with just VX Nano mice, but it’s a problem that is very common (it seems) with this mouse. I have two VX Nanos and both have the exact same issue. Forums online show it’s a common problem, hardware related, and that you have to send it in.

I of course have already pulled apart one of my VX Nanos (the first one to go bad) several times to try to fix it by cleaning it and so on, hence losing my warranty. That one is also from the US, so I doubt I’d be able to RMA it from Norway anyways. So what do you do when all hope is lost with this rather expensive $70 mouse? You fix it yourself, of course. Here’s a tutorial on how to do it with the VX Nano – the same technique will work on other mice but the pictures etc will not match up. Be aware this will of course void your warranty if you still have one.

This requires some soldering and a mouse with the same D2FC to use for parts. I recently got my hands on two Logitech MX80 wireless laser mice from a weekend deal at a Norwegian webshop for 1/8 the MSRP, so I decided to use my old MX518 cabled optical mouse as a donor for the D2FC micro switches. You might also be able to get the switches at radio shack or somewhere online, but the easiest would be an old mouse. The switches are very common.

You also need a soldering iron and you should also have (though I didn’t as I’d run out) some sort of de-soldering device, like a solder sucker or soldering remover wick. Lastly, you need some precision screw drivers – more precisely a small and a slightly less small Phillips head.

First, remove the 5 screws holding mouse together using the biggest Phillips head screwdriver (basically just find one that works). There are 3 located under the slider pads (save these, don’t ruin them!) and two under the batteries (see red rings in the picture)

Then remove the 4 screws holding the PCB to the casing using the smallest phillips head screwdriver.

Next, remove the three small screws holding the mouse wheel in place. Be careful lifting it off and pay good attention to how it sits together for when you need to assemble it again. The top part (left most screw in the picture) has a lose black plastic thing on it that you will need to put back together so don’t lose it and remember how it fits into the transparent plastic part. Take the whole scroll wheel part off including the lose parts and put it aside. Make sure to not lose the screws and sort them in piles so you know what screws go where.

Now you’ll need to detach the ribbon cable from the laser by unlocking the holder on the PCB (left ring in the picture). This is a small black “frame” around the ribbon cable which you pull up to release the ribbon cable so you can easily get it lose. Also remove the power cable from the PCB (right ring in the picture) by pulling it up.

After everything is removed and put somewhere safe, lift the PCB from the casing carefully. It might get stuck on parts here and there so just go slow and get it out in one piece.

Now you need to get the microswitches off, both from the VX Nano and the donor mouse. Use the de-soldering wick to get the solder off the three pins on the underside of the PCB . If you don’t know how: put some of the wick on the soldering point and heat it from the other side with the soldering iron. The solder should come off and stick to the wick. Do this until all three soldering points/pins are solder free and the switch can be removed. Do the same on both mice and slide the replacement microswitch from the donor mouse into place on the VX Nano. Make sure to press the microswitch down so it touches the PCVB and don’t just hang on the solder pins, and that you put it on the right way (with the actual button on the microswitch pointing up/forward) and solder it back on.

Now you need to re-assamble the mouse. Put the PCB back in and make sure it’s really in there. This might require a bit of force to make it click into place. Use the holes for the screws as a guide, these should physically click into the holes in the PCB for a right fit. Put the power cable back on and lock the ribbon cable back in place. Re-assemble the scroll wheel so that the gear mechanism work and you have no leftover parts (there’s the scroll wheel/plastic housing, the black piece I mentioned and a plastic arc piece that holds it in place). And screw that back in. Screw in the screw holding the PCB and then put the casing on and put those screws back in as well.

If everything went the way it should, you should now have a fully working VX Nano once again, complete with single-click action. If you thought this was complicated, it’s really not: I had to do this without de-soldering wick, meaning I basically half-soldered half-forced the microswitches out and back in, and mine survived fine. If you have de-soldering wick, this job should be easy for even soldering novices. Just make sure you de-solder the right pins.

Update: Video tutorial from when I fixed my second VX Nano:

Granted the one in the article isn’t all that expensive and have some nice features like rubber feet (might pick one up myself) but if you just want a cheap solution it’s very easy to make one yourself.

What you need is a pair of scissors, an old card of some sort (like a credit card, library card, phone card etc etc), and tape.

Use this template, either by printing it to fit on a card or by using it as a guide:

Plastic isn’t that bendable so the best thing is to cut it in half and then tape it back together.

That’s it. If you don’t want to spend $6 on a real stand, or just need something quick, this works wonders.

I wasn’t really planning on doing this mod because I’m getting an iPhone and won’t need it. However, I saw (in Google Analytics) that a lot of people had found their way to my ThumbTack review by googling for a splitter, so to help out these people I decided to do the mod.

First off, it’s important to understand a few things about how the microphone works. Unlike normal 3.5mm headphone plugs, it has 4 connectors instead of 3. That means that you CAN NOT USE A NORMAL SPLITTER. The microphone has two wires, each going to one of the two pins closest to the plastic part of the mic. Those two connectors on a normal 3.5mm jack, which all known splitters use, equals the ground pin and is one single connector instead of two. Therefore, if you plug the microphone into a normal splitter, you short circuit the microphone part.

To illustrate, imagine you have two different liquids that you need to carry from point A to point B in a single container, without mixing them. That would naturally require a container with two seperate rooms. If not, the liquids would mix. That is the same thing that happens when you use a normal splitter on the mic, it mixes because it lacks the seperate “rooms”.

It is theoretically possible to make a splitter from a plug and a female jack with 4 connector pins, but getting the 4 pin jacks is hard – especially the female one. Therefore I suggest to drop the splitter idea and instead add a headphone port directly to the microphone – which is relatively easy.

Disassembling the ThumbTack

First off you need to disassemble the ThumbTack to get to the inner connections. Do this by using a plier to force open the plastic at the root of the mic, not at the top end where the microphone is located. Be careful not to ruin anything, but it shouldn’t be too hard to force it open.

Parts needed

To do the mod you need a female 3.5mm (1/8″) jack with 3 pins (aka a normal one which you can buy anywhere). You also need three short wires and something to cover it up with. I used hot glue this time because the awesome Fimo model clay I normally use requires 30 min in an oven at 100°C and I’m not sure the microphone would handle that.

Adding the headphone jack

First off, solder the three short wires to the female headphone jack. Pay attention to which wire represents what channel. On a headphone plug, the area of the connector closest to the root of the plug is the ground channel, the middle one is the right channel, and the tip is the left channel. You need to trace this to the soldering points on the female jack, and it’s not always as straight forward as it might seem. Take my connector here; logic would dictate that since the tip of the headphone plug is the left channel, that part would stick farthest into the female jack and so the connector farthest away from the “entrance” is left. Unfortunately the plug has some metal parts going here and there inside the plug, so left and right has switched position. Meaning that the soldering point farthest away from the “entrance” is actually right. THIS DOES NOT APPLY TO ALL JACKS. I’m saying this because depending on what female jack you have, it might or might not be like this. Bottom line: check.

When you’ve attached the wires, you need to solder them to the ThumbTack plug. The correct pinout is shown in the picture below. Obviously you have to solder the right channel from the female jack to the right channel on the plug, left to left and ground to ground – don’t solder anything on the mic pin. If you confuse the mic and the ground pins and solder the ground on the mic pin, you’ll end up with a setup that works but has very low volume and that will sound very weird when you use the headphones, because the headphones won’t be connected to ground and the mic part will be half way short circuited.

All that’s left to do then is to test it (!) and then (if it works) encase it somehow. As I said before, I used hot glue because it’s fast and easy, but you might have something better.

To prove it works, here’s a video:

For the less geeky out there, 8 bit music is music that sounds like it’s coming from an old Nintento 8-bit console (NES). It might be geeky to some but I quite like the sound of it, maybe because I prefer music without any lyrics in it to begin with.

The program is called GXSCC and is really old, with the latest version dating back to 2002. It’s currently hosted only on Geocities which has been closed down, so expecting that the sites will be taken down shortly as well I uploaded the archieve here for sake of not letting it die with Geocities. Download it by right clicking here and selecting “save target as”. The app doesn’t require installation.

Please note that it will NOT convert music files, only MIDI. MIDI files are files that basically contain the notes and instruments used for a song, and the device that plays it back then does all the music “creation”. MIDI files are often used for karaoke, cell phone ring tones (known as “polyphonic ringtones”) and synthesizers etc. The way MIDI files work with not having the actual music recording (like MP3 files do) is the reason why GXSCC can make it into 8 bit, as it just switches out the instruments that are supposed to be used by similar sounding 8 bit alternatives. Simply drag a MIDI file (which can easily be found on Google as it’s not the same copyright shit as normal music is) and it plays as 8 bit. GXSCC will also allow you to save the 8 bit track as a WAV file which can then be converted to MP3 for playback on a portable player.

Below are some songs I converted using MIDI files I found on the net. Click on them to play them using the Shadowbox music player (switch songs by using the next/previous arrow in the lower right corner) or right click and select “save as” to download them.

Billy Joel – “Piano Man”

Bryan Adams – “Summer of ’69″

Culture Club – “Karma Chamaleon”

Fool’s Garden – “Lemon Tree”

Mike Oldfield – “Moonlight Shadow”

The Connells – “74-75″

The Cure – “Friday I’m in Love”

How to fix/change audio jacks

I’ve created a few videos to show how to change an audio jack on headphones/cables etc. The first video shows how to splice a cable, and is applicable if you for instance has cut your headphone cable by accident and need to get it back together. It can slo be used if you need either a shorter or longer cable and need to use the same plug and not a new one. The second video shows how to attach a whole new plug.

Before you watch you should know a little about types of wires. The best kind is the ones used for the cabl ein the videos, they have individual rubber insulation for each lead in the cable. No problem soldering these, just remove the insulation. Then you have painted wires. To get rid of the paint insulation, add some solder to the tip of your iron to make a small bubble to “boil” the tip of the wire in (hold the wire in the bubble). This should get rid of the paint and leave you with a soldered tip to work with.

You can normally see what kind of wire a cable has by its thickness and price. If the cable is very thing, it’s most likely made with painted wires. If it’s cheap, it’s normally the bad kind of paint. Koss PortaPro and most stock earbuds have this kind. Expensive ones normally have the good kind of painted wires. An example of this is the Beyerdynamic DT231, which with it’s 3 m cable is due for a shortening in most people’s cases.

How to splice an audio cable

How to put on a new audio jack

Don’t know what solder point leads to what audio channel?

First, download this file. The first 5 seconds of the audio file plays using both channels. The next 5 seconds is left channel only, while the last 5 seconds is right channel only. Solder the ground channel on the plug,
then connect it to what’s player the above file. Hold one of the loose wires to one of the sodler points and experiment until you find what wires goes where to make it fit with the 15 second clip.

You can also try to find out what goes where by finding what solder point leads to what part of the jack plug. Often, especially on male jacks (plugs), you can easily see what solder point leads where, which
saves you a lot of trouble.

Player jack failures

It’s not a given that it’s the headphone’s fault that the connection is failing, it might be the player. Normally you can get it replaced, but if the warranty is up, there is still hope. Changing the jack isn’t very likely to be doable, because there is more or less a different kind of jack for each player. Here are some things you can
try to make it work without changing the jack.

Broken Game Boy Color. It doesn’t work at all, but it has an audio jack so it’s perfect to show some of the ways you can fix such a jack. Note that no matter what kind of device you’re attempting these steps on,
disconnect the battery/power before you start (if possible).

The very first thing you can try is simply to find something pointy and try to bend the connectors that connect to the plug towards the center. Many times jacks liek this fail because after a while they get bent out and the plug from the headphones dont touch the metal connector in the player. Since the type of jack depend on the player, these pins might or might not be easy to access, so worst case scenario is that you use a needle and go in through the jack hole and try to bend them out from the inside. On other plugs, like this, you can do it from the outside of the jack. If it doesn’t help the connection, try the next step.

Sometimes, there is a loose or simply bad solder point on the jack, either due to maufacturer’s error, or due to long time use. It’s pretty easy to see if the soldering isnt perfect.

Solder it back on, and you might just have fixed the problem. Make sure not to short circuit anything by accidentally soldering two solder points together. If this doesn’t help your problem, try the last step.

An audio extention cable can be bought in any electronics store for a few bucks. Cut off the end, remove the solder, and solder it to the PCB (the plate that all the electrical stuff is soldered to). Make sure you
do it in a way that let you fit it inside the casing of the player, depending on what player it is it might or might not be easy. On small devices it can be difficult to track the three channels (left/right/ground) from their positions inside the jack and to the PCB. remember the little picture further up on the page, of the male
jack and the L/R/G’s pointed out. Left channel will be the connector furthest in, the middle is the right channel while ground is the connector nearest the opening on the jack. If you can find the right solder points on the PCB, and they are big enough to be soldered, then hopefully it works and your problem is fixed.