Friday, 30 September 2011

Playing music on your PC Part 1

This is my take on the whole FLAC vs mp3 controversy.

How do you check if a file is truly lossless?

From what I understand, one of the ways mp3 files are compressed from FLAC or WAV files is by cutting out the top frequencies in the spectrum. This can be seen on a Spectro* chart below. The top image is a FLAC version of the file. The peaks reach the top of the spectrum. The lower image is the same file converted to 320kbps mp3. The peaks in the second image look "chopped off". 

Track used was The Killers - Change Your Mind

Spectro is a useful tool for checking whether the file is a true lossless file or if it's a lossy file converted to lossless. The encoder used is displayed on the bottom left corner. You can get Spectro here.  It's free.

Anyway let's get back to the topic. According to the diagrams, lossless files have their high frequencies chopped off. In usual recordings the instrument that produces that high of a frequency is the cymbal. Unless you are very sensitive to high frequencies or have very good headphones and equipment that reproduce high frequencies very well, the difference between high bitrate lossy and lossless files are really tiny.

Downloading music from file sharing sites

Some of us are guilty of downloading music files through less than legal channels on the internet. Sometimes we notice a very significant between those and files obtained through legal channels. If both files have comparable bitrates, then there's a high chance that somewhere along the converting process the fellow accidentally introduced some noise into the file. I don't know how this happens but I have experienced this before. 

Blind Testing

Why? Because sighted listening is heavily biased. 

Test it out yourself
  1. Download Foobar2000. It's a great music player that uses a lot less power than iTunes. 
  2. Download the Foobar2000 ABX plugin here.
  3. Convert some lossless files (FLAC/WAV) to high bitrate lossy (MP3/AAC/OGG)
  4. Run the test.
Video tutorial (not mine)

If you can get a good result without guessing, give yourself a pat on the back.

Is a high bitrate mp3 really that important?

There's a phrase that is commonly said in audio forums; you need to have everything in 320kbps or FLAC if possible. If you have a very good headphone rig and you are the kind of person who does critical listening, then this is true. If you are that person, I don't know why you're reading my articles.

Anyways, with a very good system, the differences between a lossy and lossless sample is more apparent. But they skipped a huge step. Just having a lossless file does not ensure a high quality sounding track.  The mastering or recording of the track is more important than the bitrate of the file. Unfortunately, whether the mastering is good or bad, it's out of your hands. Mastering is entirely up to the engineers behind the album.

Some blow so much money into audiophile recordings only to find out that they're just fooling themselves. If you like listening to mainstream songs like Backstreet Boys,  Pitbull, etc, don't force yourself into buying audiophile tracks.

Building a system

This is how you should build your headphone rig, imo. Invest as much as you can into headphones. Use as much as you have left into an amplifier if you have power hungry and inefficient headphones (you can use stereo receivers instead), if not, get a decent DAC if you are still using your PC's onboard audio. Lastly spend some money on CDs or just download them off the internet and save the rest for a rainy day.

If you are on a tight budget, say.. $50, spend all of it on headphones. There are a couple of cheaper sub-100 headphones that are easy to drive and sound decent. Amplifiers come second. 

I find it hard to distinguish 400kbps AAC or 320kbps mp3 from FLAC but that doesn't stop me from loading lossless tracks on to my portable media player (Sansa Clip+). Sometimes it doesn't matter if the difference you hear between two things are real or imagined. If you think FLAC sounds better in a sighted listening test but you can't differentiate mp3 and FLAC in the Foobar2000 ABX test, then by all means do whatever makes you happy.

Thursday, 29 September 2011

Sennheiser HD438 Modifications (work in progress)

The Sennheiser HD 4X8 series are very similar in design. The internals of the HD418, 428, 438 and 448 are roughly 90% similar. The only differences are the drivers, the detachable cable (HD438). Wiring and everything should be the same on all the HD4X8 models.

All you need for the following mods are commonly found household materials. Disclaimer: Don't blame me if you screw something up while modding your 'phones. Also, your mileage may vary with these mods. Everyone has got different tastes but the good thing is that none of these mods are irreversible.

Quality vs Quantity

Bass quantity and bass quality are two different things. An increase in bass quantity will make your headphones sound a little boomy in the bass department. Bass quality depends on the headphones. Some headphones can reproduce bass that extends deep down in the frequency (20-50hz) without any problem. Some struggle to reproduce bass that low.

Examples: Denon D2000 vs Grado SR80, Ultrasone HFI-580 vs Sennheiser HD448

Most of the modifications that I will be sharing involves tweaking the bass on the Sennheiser HD438 by using different materials to mask the holes behind the drivers. This will affect the whole sound signature and the tone of the headphone. However, you cannot change the frequency response curve of the headphones without changing the drivers or adding filters.

You can experiment and come up with suitable configurations or "settings" that suit you best. 

Must-try mods will be marked with a 

HD438 internals

This is more or less what the HD438 will look like when you remove the ear pads. The yellow circles indicate where the screws are. You have to remove the screws to access the back of the driver chamber. 

The tricky part is that the screws are under the grey foam so you have to locate it with your finger, fit a screwdriver on that spot and start unscrewing. The grey foam will come off along with the screw. You will need a small philips screwdriver for this.

Removing the ear pads

Pinch at the yellow circle and pull it across the face of the driver in the direction of the red arrow. It takes quite a bit of force. Be firm. Don't go Kong on your headphones, you don't wanna have to end up paying 15 bucks for replacement pads.

1. Tape mod

If you feel the thin fabric on your ear pads vibrating against your ear and you want to remove that sensation, add some double sided tape as shown on the first image. Be careful not to cover too much of the grills.

2. Inverse ear pads mod 

As illustrated in the following picture.

Just reverse the ear pad and stick it together to the cup with double sided tape. This makes the HD438 supra-aural. I prefer using this mod when the weather is really warm. You can experiment with other ear pads from other headphones. Different ear pad shape and material results in a pretty large difference in sound.

3. No earpads 

Without the earpads and with the cups not touching the ear as illustrated above, you get the clearest sound. If you like the HD4X8s this way, I suggest getting some cheap ear pads that resemble quarter modded Grado comfies and stick them onto the cups. This setting is perfect for piano (imo) but doesn't really work well with club music and rock songs.

Edit: second thoughts --> I don't like them like this.

4. Dampen the inner cup surfaces

There isn't much space between the inner surface of the cups and the driver when you put everything back together. If you put too much blutack or plasticine on the surface, you might not be able to fit the driver back in properly.

If you like opening up your Senns to mess around with the internals and do some further tweaking, the bluetac might make it really difficult to pry the cup from the driver. I used a coin for this.

The blutack dampens the resonances in the cups to make the sound less muddy.

5. Dubstep mod 
Step 1: Remove the tape covering the 3 holes.
Step 2: Apply a thin layer of blutack on the inner surface of the cup to dampen resonances.
Step 3: Put everything back together. 

The back of the driver enclosure. The black tape is covering 3 holes. The black tape used here is semi-permeable and allows air through it. Uncover all three holes for maximum bass quantity.

This is the surface of the cup. 

Cover this area with a layer of blue tack. Make sure it is not too thick but don't spread it out too thin either. 

What I did was remove the small circuit board first so that I could apply some blue tack underneath it. This makes the thin wires less prone to breakage.

6. Bring out the highs 

with an equaliser.

Tune up the equaliser to +5db at 10kHz and the change should be gradual starting from 2kHz, so step the equaliser down by 1db as you go along. You should end up with a gradual slope as indicated on the right hand side of the image. If you want to be a little more adventurous, equalise the mids a little. What I did was +1db at 220Hz, +1 db at 311Hz, +2db at 440Hz and +2 db at 77Hz.
The increase in highs gives the impression of a clearer sound signature, at the cost of sibilance. Vocalists such as M. Shadows of Avenged Sevenfold sound a little sibilant after equalising but it's not too bad. I think this is a must-do for the HD438. Even if you're against equalising, try it out. You don't need a sophisticated equaliser program, the Foobar eq will do.

7. Neutralised HD438 (sorta) 

Things you need: 
1. Gauze or bandage (doesn't need to be new/clean).
2. Some blutack, putty or plasticine. 
3. Philips screwdriver and maybe a small coin to open up the cups.



As you can see from the image aboves, I applied some blutack around the 3 holes and then stuck some gauze on the blutack to act as the filter. Without any material/filter covering the holes, the bass will be overwhelming. I actually used the gauze I "tore off" my SR60. I suppose speaker cloth could work just as well. Extra porous bandages are good substitutes if you don't have any thin gauze.

I'm currently using this with the ear pads on and with the equaliser settings I posted above. After modding and applying the EQ, the same warm sound signature is retained but since the bass is leaner, highs are a little more prominent giving the impression of clarity. I think it sounds a lot cleaner. 

Currently listening to The Killers, Radiohead and other random songs on my Sansa Clip+ and E7. Love this set-up. 

By the way, the ear pads used is a huge determining factor of the overall sound signature. Some pads make these headphones sound very shrill and thin, some give the headphones warmth or a more full bodied sound.

Experiment with the holes. Use different materials. Instead of blue tack, use cloth, etc. Some configurations are really bad but the only way to find the type of sound that suits you best by trial and error.

My Current EQ settings for HD438

It's the one on the right. As you can see, the Equaliser settings are pretty huge. It goes up as far as +5db on some frequencies. I did this to make the headphones more detailed at low volume. The Equaliser I'm using is actually the ElectriQ Fosihfopit (free). It works great on Foobar.

Sennheiser HD438

Short story

My father bought me the HD438. My first headphone. I was going to get the HD418 which is about $100 here, but he insisted that we get something higher up the line so I settled with the HD438, which is about $130. A couple of months later I bought the SR60i. He was pretty down about it... When I hear others say how crappy the cheaper Sennheisers are, I get a little mad inside, lol. These headphones are very special to me. $130 is quite a lot to spend on a hobby, especially since I don't have a job and my dad only earns enough for us. I mean srsly, if you offered me the HD600 to trade for my HD438 I wouldn't. Or maybe I would. I'd sell them and use the money to get a new pair of HD438s, and then spend the rest on pizzas. Hue.

Moving on to the review...

The Bad

This headphone is always overlooked and under-recommended.

The word that has been going around in audiophile circles since forever is that anything that is flashy is Skullcandy and anything Skullcandy is bad. The Sennheiser HD438 have got chrome spokes that really make you stand out in the crowd. In my opinion, they look pretty sleek and certainly not as bad as Skullcandies which are just so gaudy. I have a classmate that thinks my HD438s look too plastic.
The build quality of the Sennheiser HD438 is decent but they cannot be thrown around. They are not collapsible so storing them in your bag might be a little difficult. 

The Ugly
Not for use in hot tropical climates, unless you are always in a controlled environment. The velour pads can make your ears really warm. Not for anal guys who love their headphones FR to be flat either. 
The Good
They are circumaural closed headphones. Most closed headphones do not leak as much sound out as open headphones, even if you turn the volume up. You can use most circumaural closed headphones in quiet public places, such as libraries, public transport, etc. Of course there are exceptions like some Denon headphones. 
Very little sound leakage also translates into good isolation from the outside world. However, there is an important difference between circumaural headphones and active noise cancelling headphones. Circumaural headphones do not use any special technology to block outside noise, they just cover your ears like ear muffs. Active noise cancelling headphones require batteries. The mechanism in the headphone will produce some sort of wave that cancels out noise coming from the outside world. I'm not really sure how this works but you can read up on it on wikipedia. The HD438s are circumaurals that do not block outside noise.


The Sennheiser HD438 is very comfortable. This can be attributed to it's lack of clamp force and velour pads. Those wearing glasses will have no problem living with the HD438. They're also perfect for watching movies. Those who love to headbang claim that the lack of clamping force is a problem, and they're right. It really depends on what you use them for.   

The HD438 has the trademark Sennheiser sound signature. Sennheiser headphones have a very dark character as opposed to some headphones which sound bright like Grado or Shure. The problem with bright headphones is that they're fatiguing (imo).
The packaging on the HD438 says that the headphone has enhanced bass. They do have good bass extension which is to say that they reach really low into the sub bass region (good for dubstep) but they lack the bass slam or impact (bad for dubstep, good for rock) compared to other headphones like Sony XB5/700.
In stock condition, these headphones are decent. They do not really do anything exceptionally well, like how the Grados excel at guitar and drums. A little EQing will bring out the best in these but for $80, they sound pretty good. I'm a big fan of equalisers btw.
There are tweaks that you can do to the Sennheiser HD438. More on this in the next article. I will put up some images of the Sennheiser HD438 but they are not in stock condition, I've made a pretty huge cosmetic "upgrade".



About me

Hello. I'm JB. I have always been into music but I'm fairly new to headphones. My first headphone was the Sennheiser HD438, followed by the Grado SR60i. In the last four months, I have spent a lot more on this hobby than on any other. This is also due to the fact that headphones, amplifiers and other audio tweaks are way more expensive here than in the US.

I'm currently pursuing a diploma in Aeronautical Engineering. Most of the reviews and tweaks on this blog will be purely subjective in nature as I do not have the means to test out the headphones with proper equipment. However I will post some links to external sources that may contain a lot of techy-mumbo-jumbo where I see fit.

Is this just another audio blog?

Why yes, yes it is. Like many other audio blogs on the internet, mine is no different. I'm here to pen down my thoughts on things related to audio, namely music, headphones, headphone tweaks and amplifiers. Maybe some other things, I don't know yet. I currently own a really modest rig that I'm content with.

I'm not an audiophile but I do appreciate good music. 

Favourite music?

Most of what I listen to is mainstream music. I'm not a huge fan of metal, country and classical music. I'm more of an alternative rock, indie, electronic, dubstep and acoustic guitar type of person. My favourite bands are The Killers and Arctic Monkeys. 

pe-arctic-monkeys-humbug.jpg (480×480)

There's just something about The Killers' music that really calms me.