Pitfalls of Vacuum Tube Amplifiers

Woo Audio WA3

The vacuum tube amplifier is something that all true audiophiles yearn to own at some point, if they don't already.  There is something unique and special about the warm, rich sound produced from a vacuum tube amplifier as apposed to a solid state amp.  Even I have been eyeing vacuum tube amp's for the last few years like the Schiit Audio Valhalla and the Woo Audio WA3.  I am positive that a pair of Sennheiser HD 650's, the Valhalla vacuum tube amplifier and some sort of quality DAC (most likely the Schiit Audio Bifrost) would sound truly spectacular.  However, someone who is unacquainted with vacuum tube amplifiers should be aware of a few pitfalls associated with vacuum tube amps.

There is no doubt that if you are looking for the purest analog sound possible, the vacuum tube amplifier is the way to go.  Todays solid state amplifiers lack the rich and luscious sound that the vacuum tube amplifier provides.  However, the biggest pitfall of the vacuum tube amplifier is well... the vacuum tubes.  Vacuum tubes are an extremely antiquated technology making them relatively expensive to replace and yes, you will be replacing them.  There is also the issue of quality.  Not all vacuum tubes are created equal.  The crappy ones will often muddy the sound as well as affect the sound signature of your expensive amp in a variety of negative ways.  The better vacuum tubes obviously sound better, but they tend to be much more expensive than their low end counterparts.  There is also different types of vacuum tubes that you can select.  Each different tube produces a slightly different sound signature when paired with your amplifier, so selecting the proper tubes can sometimes be a chore.  You must also understand that almost one hundred percent of the vacuum tube manufacturing process is done by hand.  This results in vacuum tubes that are ever so slightly different from each other. Most of the differences are almost imperceptible to the regular listener, but the discerning audiophile can often pick up on the differences.

Schiit Audio Valhalla

Vacuum tubes will need to be replaced from time to time as well.  Smaller tubes tend to last anywhere from five to eight years depending on use.  Typically, the bigger the vacuum tube, the less time you can expect it to work (although this rule does not always necessarily hold true). Many big tubes will only last from one to three years.  It all depends on how hard you push your amp, for how long you use your amp and the quality of the tubes.  Because of all these factors, it is hard to definitively figure out how long your vacuum tubes will last. One last rule in vacuum tube life is that they will often burn out faster when using harder to drive headphones (because obviously the tubes are being worked harder by high impedance cans).  For example you can expect a Woo Audio WA3's power tube (the largest vacuum tube on the unit) to burn out quicker if you are driving a pair of 300Ohm Sennheiser HD 800's as apposed to the 150Ohm Sennheiser HD 700's.  Tube life is very hard to determine due to a host of effecting factors, but the main point I am trying to make is that if you have a vacuum tube headphone amplifier, you will be replacing the vacuum tubes at some point.  Replacing the tubes obviously costs money and thats why vacuum tubes can become a bit expensive to maintain over the years.  Some smaller tubes can cost around $10 to $15 dollars while the bigger tube can cost upwards of $30 to $40 dollars each.  With a vacuum tube amplifier that has say four tubes, it is probable that you will be investing an additional $60 to $100 dollars into the amplifier over a period of 3 to 5 years.  Some really expensive amplifiers have several tubes and obviously with more the more tubes you have, the more costly it becomes to replace them.

Schiit Audio Valhalla Tubes

Another, somewhat minor pitfall with vacuum tube amplifiers is vacuum tube burn in and what I like to call "vacuum tube roll-off".  When you first insert brand new vacuum tubes into your headphone amplifier, they need a chance to burn in, similar to a brand new pair headphones.  Your tube amplifier wont reach it's full sound quality potential until new tubes have been used for a few hours.  Vacuum tube roll-off occurs a few years later  when your tubes are no longer new.  As they begin to get old (nearing burning out) the sound quality tends to decrease.  It continues to decrease until eventually the tubes burn out and are need of replacing.  The primary indicator of an old and worn out vacuum tube is when the sound quality begins to decrease.  Many people replace the vacuum tubes during this point because they know that they are nearing the end of their life.  This is a common practice, as using the tubes until they burnout can, in relatively rare cases, damage the headphone amplifier. A few other vacuum tube amplifier related pitfalls are that when the amplifier is first switched on it needs a good minute or so to warm up the vacuum tubes before you begin listening and that vacuum tube amplifiers tend to produce much more heat and in some cases require more power than their solid state amplifier counterparts.

The pitfalls listed and explained above are the major possible downsides to the vacuum tube amplifier.  This post is in no way intended to dissuade people from purchasing a vacuum tube amplifier.  In fact, in my personal opinion, the benefits of the vacuum tube amplifier far outweigh the detriments as a good vacuum tube amplifier paired with quality headphones sound's truly spectacular in comparison to even some of the best solid state amplifiers.  It's really an experience that is difficult to describe, except that a good vacuum tube amplifier often makes a standard solid state amplifier sound cold and lifeless in comparison.  Tube amplifiers tend to produce a much more rich, lively and often times detailed sound signature, although keep in mind that this is not always true as there are quite a few good and expensive solid state amplifiers out there as well.  I feel like it is important for anyone on a tight budget looking at tube amplifiers to understand that you are going to have to spend more money on it in the future, and that vacuum tubes do have limited life spans.  I would highly recommend a quality tube amplifier to anyone who is serious about high end headphone audio and for someone who actually has a headphone that can benefit from it (sorry, but your ATH-M50's will most likely not benefit from a tube amp).  If you have a moderately or even extremely hard to drive audiophile class headphone, are serious about the best headphone audio has to offer and are willing to pay a pretty penny on an amplifier and some more money on the tubes in the future, then a tube amplifier is for you.

Below I have linked several companies that make quality tube amplifiers.  Some of them even sell the individual vacuum tubes as well!

CLICK HERE for Schiit Audio
CLICK HERE for Woo Audio
CLICK HERE for Eddie Current Audio
CLICK HERE for ECP Audio
CLICK HERE for Cary Audio
CLICK HERE for Icon Audio

Sennheiser HD 400 Line Build Issues Response

From left to right, HD 429, HD 439, HD 449

Now that I have had a chance to listen to the Sennheiser HD 429, purchase a pair of Sennheiser HD 439's and also borrow my friends Sennheiser HD 449's, I have actually become quite impressed with the Sennheiser HD 400 line as a whole.  What I intend to do is challenge a few of the negative reviews that this line of headphones receives from many online reviewers.  The Sennheiser HD 400 line receives mostly glowing reviews, but the negative reviews typically consist of negative speculation about what might happen to the headphone over time, not how they perform as of current.  Every headphone (especially in this price bracket) has a few weaknesses.  I get that.  But in my personal opinion, build quality is not one of them.

In almost every single negative review, reviewers constantly cited the "cheap, plastic" feel of the headphones as the reason why they "knocked a star off" or "couldn't recommend them".  Many of these negative reviewers speculate that these headphones are just going to fall apart in a few years.  But heres the thing: I never once read a review that said that they HAD fallen apart.  I have come to the conclusion that the reason for the Sennheiser HD 400 line's "cheap, plastic" build is simply because Sennheiser wanted to create lightweight and comfortable over ear headphone line.  Just because something is built from lightweight plastic, doesn't mean they are built poorly.  Aside from the headphone's size adjusting mechanism, I was actually quite impressed with the build of my Sennheiser HD 439's when I got them.  In fact, the headphones are capable of being stretched and contorted into shapes that would make the screws pop and the plastic crack on a pair of Beats by Dre headphones (of course, if they screws haven't popped already from regular use).  The hinges also don't creak when the headphones are stretched to put on your head.

A demonstration of the Sennheiser HD 449's impressive
headband flexibility.  These headphones continue to work
perfectly fine after this test, no plastic stress marks and no
build issues to report.

Sennheiser is a tried and true headphone company that manufacturers proven quality audio products.  The HD 400 line was specifically designed to be a line of lightweight portable over ear headphones (hence the lightweight plastic).  The only build issue's that I know to be one hundred percent true, is that the hinges to wear out over time and they become a little bit loose.  Aside from that issue (which is common in many headphones that are heavily used) the Sennheiser HD 429, 439 and 449 will provide lasting quality for many years of audio enjoyment.

Sennheiser HD 439 Review

Sennheiser HD 439

I recently purchased a pair of Sennheiser HD 439 over ear headphones at my local BestBuy.  I had several reasons for doing so.  Firstly, the headphones were on sale for $80 dollars ($20 dollars off the regular price of $100 dollars) plus I had a $50 dollar BestBuy gift card.  Secondly, I was in need of lightweight, reasonably priced, well built and decent sounding over ear headphone that were able to be sufficiently powered by my portable devices.  All of my other headphones (with the exception of the Sony MDR-XB700's which are far from being portable and quite honestly look ridiculous) are professional studio monitor headphones that have long, coiled cables and that are designed to be powered by professional audio equipment and amplifiers.  My Sennheiser HD 280 Pro's and Sony MDR-7506's are far from being portable and with both of them having a 64Ohm impedance, they don't play well with portable devices and their puny power outputs.  Enter the Sennheiser HD 439's, which after some research on my part, seemed to be the solution to all my problems.  I initially considered purchasing the Logitech UE 6000's, but after much deliberation I decided that they were simply too costly and I have never been a huge fan of active noise canceling headphones because they require batteries.  I settled for the trusted quality of Sennheiser and I am glad I chose to go the Sennheiser route.  Sennheiser has been in the business of designing and manufacturing quality audio products since its start in 1945 and I am pleased to report that I am more than happy with my new Sennheiser HD 439's.  Before I truly review these cans though, let me overview what was included in the box and some features that the headphones possess.

Sennheiser HD 439 headphones and packaging

While Sennheiser headphones have a reputation for looking and sounding great, their packaging tends to be a bit lackluster. In my opinion, packaging really only has to complete one task: get the product inside to your door or to the store shelf safely while protecting the product from damage. The packaging for the HD 439's passed this with flying colors, its just that the box is one of those annoying sealed plastic containers that takes you ten minutes to open and requires the use of scissors.  The packaging lacked the fancy presentation that many Sony headphone products give, but I am willing to give up a fancy box for a well made product.  I was pleasantly surprised to discover that the Sennheiser HD 439's have a detachable cable.  For whatever reason even after all the reviews I read and looking at the product page on the Sennheiser website, I never read anything that mentioned a detachable cable.  Two cables were also included in the box, one 1.4 meter cable for use with portable devices and a much longer 3 meter cable extending the range in which someone could use the headphones.  A 6.3mm  adapter plug was also included, which I thought was a nice touch despite the fact that most people wont be using these headphones with an amp that has a 6.3mm headphone port, or with an amp at all for that matter.  My only gripe is that no headphone bag or carrying case is included with these headphones, which I found to be slightly irritating, just because these are going to be my travel cans.  Once the box is opened, the headphones are snugly incased in a molded plastic piece.  Behind this plastic piece is a printed cardboard piece with technical specifications and a picture of the headphones on it.  The HD 439's have a frequency response of 17Hz to 22,500Hz, 32Ohm impedance, 40mm Neodymium drivers and a max SPL (sound pressure level) of 112 dB.

Sennheiser HD 439 headband

The first thing I noticed about the HD 439's when I removed them from the packaging was how incredibly light they are.  I was already expecting this because I had borrowed a friends Sennheiser HD 449's in the past, and the HD 449's are almost identical in weight to the HD 439's and are constructed in a similar fashion from identical plastic.  Due to the lightweight nature of the headphones, many people assume that they aren't built very well.  Yes, the HD 439's are made entirely from plastic and yes they are very light.  However, this is to be expected in a $100 dollar pair of headphones and is pretty typical across the board for all over ear headphones in this price range.

Sennheiser HD 439 ear cups and velour ear pads

Only will time will tell how well the HD 439's hold up durability wise, but my before mentioned friends HD 449's have held up fine for quite some time, so I am not too terribly concerned.  Additionally, with the cable being detachable and the pads being replaceable, if anything does wear out it can be easily replaced.  Two annoyances I have with the build is that the sliding function for adjusting the headband size is a little clumsy, it feels a little loose and doesn't give a solid click when adjusting.  The other annoyance is that the cable tends to produce some cable noise.  This issue could be remedied with a slightly thicker gauge wire with more insulation.  Besides that, I am pleased with the built.  They feel solid and the joints don't creak or anything when the headphones are stretched.  They have velour pads that are extremely comfortable.  The headphones have just enough clamping force to keep them on your head but not too much to cause discomfort.  This coupled with the velour pads and the extremely light weight result in an headphone that can be worn for hours without discomfort.  My ears never get sweaty or fatigued when wearing the 439's for extended listening sessions.  The velour pads breathe very well.  The headband pad is also velour and is the proper thickness to supply sufficient levels of comfort.  While the light weight feel of these headphones may make them feel cheap, I believe that Sennheiser purposely intended to design these headphones out of lightweight plastic to make them more comfortable, easier to carry and more portable.  Sennheiser is known for making durable, long lasting quality headphones.  I doubt that the HD 439's are going to fall apart on me any time soon, but like I said earlier, time will tell.  One thing I should mention is that the cable lacks a play/ pause, volume controller and mic button.  I actually prefer this as many of the cables with the iDevice compatible buttons on them tend to go bad quicker as the connection into the button housing breaks under the stress of use.   From an aesthetics standpoint, I find the HD 439's very appealing.  I personally love Sennheiser's styling with many of their $100+ dollar headphones.  They look sleek, refined, modern and not over the top (Beats by Dre anyone?).  They are not overly flashy and look simple and reserved.  The pictures honestly don't do them justice, they look much better in person. My favorite aesthetic feature is the thin chrome like piece that encircles the black grille and the Sennheiser symbol.  The only thing I wish that they did was perhaps paint the Sennheiser logo on the top of the headband silver or white.

Now for the most important factor of all: sound quality.  This is another area where these headphones pleasantly surprised me.  After being spoiled by my professional class headphones that I often listen to from an amp, I wasn't expecting much in the way of sound quality coming from the Sennheiser HD 439's when paired with my laptop or iPhone.  What I discovered is that these headphones perform better than I had ever expected.  Even after a mere five hours of burn-in, they were sounding great.  Sennheiser advertises "extended bass response" on the front of the box.  This is often misinterpreted by consumers as "extended bass boost".  What it actually means is that the bass can achieve much lower frequencies without significant roll off or reduction in volume.  It however is not a "bass head" headset. The bass is relatively equivalent to the mid range, and is tight and controlled.  They perform well enough with bass heavy genres like dubstep and electronic for my tastes, but I am not overly bass crazy.  My only gripe with the bass is that while it is tight and controlled it lacks the punch that my Sony MDR-7506 and Sennheiser HD 280 Pro's have.  While listening to Rush's "Clockwork Angels" album I noticed that Neil Pearts powerful bass drum kicks don't have as much punch and power as they do on my other headphones.  The mid range is very nice but is only ever so slightly recessed.  The cans represent vocals very well as well as electronic and rock music.  Something I really I like about the high range on the 439's is the fact that it isn't aren't overly dominant or piercing.  They lack much of the annoying sibilance that my Sony MDR-7506's have that makes listening to rock music with lots of symbol usage almost unbearable.  They are a relatively warm sounding headphone, and keep in mind that these are consumer grade headphones that are not designed to be overly analytical and in this case, its an attribute that I actually like.  The only other issue I have in regards to sound quality with the Sennheiser HD 439's is that they tend to distort at high volumes.  This was pretty much the only area where I was a little disappointed with the HD 439's.  My Sennheiser HD 280's Pro's and Sony MDR-7506's can go roughly 40% louder than the HD 439's without distorting.  However, I cannot get the HD 439's to distort on any song when playing them on max from my iPhone, and can only get them to distort on certain songs when playing them on max from my laptop.  In this sense, it's not really an issue because I never play them on max from my laptop because it's just too loud.  Overall if I was to rate the sound quality of the Sennheiser HD 439's I would give them an 8.5/10.  When you consider the price and their intended use, they are actually quite good.  I only took points off for lack of bass punchiness and the fact that they distort at higher volumes.

Two cables included in the box

All and all, the Sennheiser HD 439's are good all rounders.  They are far from being as analytical and revealing as my studio monitor class headphones, but thats not the point.  They are capable of being played at relatively loud volumes on portable devices, and they have a relatively warm sound signature that I really like.  The detachable cable and the fact that the ear pads are replaceable makes me feel confident that if anything ever wears out or breaks, I can just purchase the part and not an entire new pair of headphones.  I personally like the level of bass presence and depth but I don't care for the lack of punchiness.  These are not "bass head" headphones, but for the average listener who wants a relatively inexpensive, great looking, great sounding extremely light weight and comfortable over ear headphone I highly recommend the Sennheiser HD 439's.  They work very well for all different genres of music making them good all round headphones for all types of listeners.