Fast bass? Slow bass? What's yours then?

I was recently reading the thoughts of someone whose knowledge of AV equipment and acoustics I value greatly. He raised the matter of bass speed being a function of bandwidth. My understanding of his words suggests that fast bass requires higher frequencies. While very low frequencies, left to their own devices, are inherently slow. At its most simplistic, the situation could be likened to having one's ears buffeted by a hot air balloon. Or whacked by a baseball bat. The argument seems logical enough. Pluck a double bass near the bridge and it "quickens up" compared with the soft, plummy depths of open strings plucked near the centre.

Yet the description of likely events in audio reproduction has always troubled me. More so since the arrival of the IB subwoofer. The IB produces prodigious quantities of very low frequencies with low distortion. Perhaps the rumour of slow VLF bass arises from the long history of ported boxes? The artificial augmentation of the lower registers (by port-enclosure resonance) has obvious problems of phase, delay, distortion and inertia. i.e. It only sounds slow because it is. While, repeated almost in the same breath,  a sealed box will avoid all the problems associated with the ported box.

Meanwhile, back at the ranch, the IB suffers no such delay and can bring acres of cone area to the task of bass reproduction. If, as we surmise, the IB produces much less distortion then why should it produce unwanted harmonics? Wouldn't artificial harmonics be vital to providing the upper bass content to "speed up" the bass? The IB, when fed pure VLF signals, should sound slower. As should the rotary fan subwoofer by an order of magnitude again!

Yet the IB sounds remarkably nimble. It can dance with the best of them in the infrasonics. Organ pipes start and stop abruptly. Explosions and doors banging are not only incredibly realistic but move a lot of air. Enough to produce very short and violent movements in doors, walls and ceilings. Completely silent infrasonic (film LFE) pulses can quite literally hurt one's feet by sound conduction through a boarded floor!

Not only did the silent pulse produce a very fast, transient, very low frequency pressure wave-front from the cones. It then had to transfer the power by the medium of the air pulse alone to the surface involved. Doing so quickly enough to produce sympathetic resonance to achieve the violent, physical effect. So even though the floor movement was a very "secondhand" expression of the wave-front "air blast" from the IB.. it was still a very short and sharp movement in the floorboards. How fast is your deep, silent bass?

As a long term amateur audio fan I am not remotely a physicist nor even an acoustician. Yet I hear about bass being inherently slow almost every time I read about the subject online. As if it were a physical law set in stone. It is almost like reading that nothing can exceed the speed of light. But without the massive authority of countless, very clever scientists to back up the assertion. Audio seems not to attract too may headlines from the "heavy hitters" of science. Nobody makes "dumbed down" TV documentaries on exceeding the speed of bass. Well, not yet, they don't.

Does a very low frequency have to reproduce the entire (very long) waveform before it can be perceived as a low frequency? Aren't VLF blasts the accepted way of bombs damaging buildings? Percussive pulses and following rarefactions overcoming the stability of the structure by exceeding its strength. Usually via a perpendicular vector to which it has inherently, very little stiffness. Most buildings are held together by friction and gravity. Provided they don't topple in a gale everybody gets on with their lives.

What would happen if you electronically chopped up a pure, continuous, VLF tone? It could even be done mechanically. Perhaps using a microswitch and variable speed, motor driven cam in one leg of the speaker cable to the IB.  What would one hear? Short blips of the VLF tone? Or something else entirely?  I am assuming that (for the sake of this argument) the IB's power amplifier would not become unstable when so abused.



New cable for Sennheiser HD-380 Pro headphones for home audio.

My 1980s Sennheiser HD-420SL earphones have finally given up the ghost. Pressing the cables upwards towards the headphones sometimes helped but relief was usually intermittent at best. I could have ordered a new cable. They are still available despite the intervening decades. They have little 2-pin plugs where they fit the headphones. Though one has to grasp the strain relief device firmly to get sufficient purchase for removal. Pulling on the cable itself would no doubt shorten the life of the copper conductors dramatically.

However, the '420 SLs would still have the singular disadvantage of being open-backed and therefore largely transparent to ambient noise. I had recently begun enjoying YT music videos but suffered competition from the nearby TV.

I sit at my computer tapping away at the keyboard as I update my blogs or browse as I listen to music. I was never a much of a TV watcher and hate having to listen to the drivel even when I can't see the celebs embarrassing themselves in as many unfortunate ways as possible.

The SQ on YT is not always the best but it does offer a huge selection to help one reacquaint oneself with favourite composer's and artist's repertoire. Fortunately YT continues to make improvements in both sound and picture quality. These improvements further encourage users to upload new material to the benefit of all. (Except perhaps some copyright holders who have never knowingly lifted a creative finger in their entire lives.)

The failure of my headphones coincided with my cheapo computer speaker's own cable failing where it joined the stereo mini-jack. What to do?

Go online and research closed back, circumaural headphones, of course. I had no real clue what my price point would be but it seemed that a small band of manufactures produced so called "monitoring" headphones for studio use within a fairly narrow price band.

I dutifully did my homework amongst the online reviews and forum posts and narrowed it down to my eventual purchase: The Sennheiser HD-380 Pro: Closed back, with decent noise reduction and all in a smart, modern and tidy design.

Being denied open backed headphones and having a dislike for ear buds and on-ear designs helped to avoid the much higher priced models with a clear audio conscience.

The sky really is the limit for those with sufficient ill-gotten gains to spend up to $30k on a pair of headphones and amplifier. Since I have somehow avoided running slaves "for a living" my finances, needs and ultimate choice were far more modest in all senses of the word. For $30k the filthy rich could afford to hire the original artist. Nay even a whole orchestras for a private dose of self gratification. How much is the cost per minute of musical replay over the life of a $30,000 headphone?

I also happen to think that the more you spend on audio components the more you demand of them. That way lies only misery, poverty and the torture of self-inflicted pain. Better, surely, to enjoy what you can comfortably afford and get years of real pleasure out of listening to your personal choice of music? Competition for bragging rights provides no greater pleasure in the medium itself. Only self doubt about your ultimate choice.

And so the rehearsal for its replacement begins. You have already written off your latest purchase as worthless in your own mind. How can it now give pleasure or sway the emotions as you fail to wallow in your favourite artist's renditions? How much extra do you need to pay for a guaranteed shiver down the spine on the fifth playing?

Armed with my list of competitors I compared the popular closed headphones on the dealer's 'tree.' Each has their ardent followers but I found them all too bright on the material being played. Probably an attempt by the manufacturers to grab the potential buyer's attention with exaggerated detail. I asked to listen to the HD-380 Pro which was not on open display but stored in unopened packaging nearby.

The music track changed to something I knew and the Sennheisers immediately presented themselves as worthy contenders without deliberate artifice. The bass was clear and strong with neither overemphasis nor lack of impact. Though still rather brighter than I was used to there was no sibilance at the top end. Nor anything which would set my teeth on edge. I paid and left with my next increment towards inevitable pleasure in the music to come. That the Sennheisers had been favourably discounted would have to do for my own version of bragging rights. Soon forgotten as the years pass and the supposed savings rationed out over the life of the product.

I rapidly adjusted to the brightness as my ears became "burnt in." Though in truth the ear cups do not cause overheating in practice.  (Yes, I know this particular vial of priceless snake oil is not what is meant by the term)  Perhaps 'burning in' is the really just the consequence of enjoying new headphones and its inevitable effect on the wax contents of the ears? Whatever.

What I cannot get used to is the damned cable! Coiled like any serpent of your worst nightmares, it weighs not much short of half a pound! It is ridiculously heavy! Within five minutes I detested it with all the vehemence I could muster. The cable pulled the headband down on my scalp like a lead weight!

The CIA would never get away with this at Guantanamo. There would be an outcry from every hypocritical bleeding heart around the globe if the prisoners were forced to wear HD-380s. "Cruel and unnecessary treatment" doesn't even begin to describe it. Permanently aching neck muscles are the immediate consequence of this particular "rack" of Sennheiser's range of medieval torture devices. In the longer term I could end up looking like a very lop-sided Arnie! And it's all down to the damned, coiled cable!

I am sitting here now with the cable coil trapped between my knees as temporary strain relief. Thankfully, I have a lightweight cable already in the post to replace the good ship Sennheiser's massive hawser.

The new cable will be a dirt cheap 2.5mm micro-jack to 3.5mm mini-jack adapter cable a couple of meters long. If the micro-jack plug fits into the bottomless orifice which Sennheiser have managed to bore with the help of an offshore oil rig I shall be delighted.

I shall report on the new cable's benefits and sound quality when it arrives. I hold no illusions that it will survive being badly snagged but hopefully the plug will simply pop out without damage. Nor do I have illusions that electrons either know or care which medium they travel through provided it conducts adequately and the insulation is not too microphonic.

Despite the heavy cable the new headphones sound fine when plugged into the on-board sound card of my PC to play CDs. Not quite so fine on brief acquaintance when  plugged into the NR818 AVR being fed from the Sony BDP S790. Fortunately the phones sound surprisingly good on many YT videos straight from the PC's internal sound card. Organ videos are interesting for their depth and power though I miss the physical vibrations from the IB. There is excellent dynamic range on most material.

More later:

The new cable quickly turned up in the post but, exactly as I feared, the 2.5mm microjack body would not fit. It measured exactly 10mm in diameter when I really needed a maximum of 9mm. Beggars can't be choosers!

Being solid plastic, the plug body responded readily to abrasion. I chose to use my lathe to reduce the forward part of the major diameter concentrically but finished off the rear half with files and emery sticks. Anybody without a lathe chuck could hold the plug body in the chuck of a drill. NOTE: NOT THE TIP!

I kept the majority of the cable in the supplied bag to keep it clean while I worked on carefully making the 2.5mm micro-jack plug body smaller. I was very careful to avoid damage to the plug's conductive tip.Notice how the diameter at the tip is reduced via a taper. This would not survive much in the way of physical force.

Careful examination of the headphone socket suggests two raised plug location ridges may cause trouble if the plug body is still oversized for the space available. These ridges align the original triangular plug body which has matching grooves. It might be well worth providing two flat on opposite sides to avoid the ridges interfering with the entry of the new plug. I just filed a flat on either side of the plug body after reducing it to 9mm nominal diameter.

Once brought safely down to 9mm over its entire length the plug needed to be pressed gently into the bottom of the space where the triangular part of the Sennheiser plug body normally sits.

Only when it was parallel with the socket could I push the plug gently home. I have made no real effort to smarten op the (now smaller) plug body since it is almost invisible when fitted into the headphones. Most of the body length is hidden in the 9mm deep plug socket in the headphone body.

Do NOT attempt to fit a plug larger than  9mm diameter or you may well break off the plug tip as it will certainly enter the socket askew! How could it be otherwise? You may even crack the headphone's own moulding! Do NOT use force! The plug body must press effortlessly right into the bottom of the moulded cut-out groove first. Only then can it be pushed safely forwards into the headphone micro-jack socket itself.

Any tilting of the plug will surely lead to a flood of tears! Any tightness between the new plug and the Sennheiser body will make removal of the plug and cable very difficult indeed. Patience in reducing the plug to under 9mm will be rewarded.

Do not blame me for your inadequacy if you break anything! Anybody who needs an ambulance chaser to protect themselves from their own drooling idiocy probably needs a wet nurse. Not a sympathetic jury of similar inadequates. All wishing they had won the court lottery themselves without ever lifting a finger.

Talking of which: Flicking the new cable with my finger nail produces no sound in the headphones. So microphony is certainly not an issue. How much current is the cable being asked to carry? Not enough to worry about resistance, impedance or capacitance. Nor any of the other half-understood techno-babble underpinning your desire to expend more money than strictly necessary. I paid roughly £4/ 40DKK/ $6.50 for my shiny new, adapter cable online.

So far I can detect no difference in sound quality using the "cheapo" cable. Why would it be otherwise? The headphones now feel quite lightweight and are much more comfortable. I no longer need to fiddle constantly with the ear cups trying to take some of the excess weight of the original cable off the headband. I have even been able to discard the hat which I was using to protect my scalp from the pressure of the original cable via the headband. I have worn the headphones for hours now without discomfort or the previous distress.

The degree of isolation from the closed back design is perfect for domestic use. The Sennheiser HD-380 Pros have plenty of rhythm and no obvious vices! Their non-tiring clarity means that I am hearing backing singers and instruments I never knew existed on tracks I have enjoyed for decades. The HD-380s  seem to excel with all kinds of music from electric folk to rock to classical. The fine separation of sound sources across the soundfield is remarkable. Percussion is particularly well rendered. Highly recommended as a candidate for your own perusal! Though only IMO, of course.

Update: I had excellent feedback from Sennheiser's Danish office to my email tirade about the heavy coiled cable. They even promised to consider offering a lighter cable as an option for those who would prefer it. I reiterated my emphasis on the need for a closed back headphone for those who do not enjoy total background silence while listening to music. This made the HD-380 Pro an excellent option for those with families. Or even bus and train commuters.(But NOT cyclists!) Open backed headphones are a scourge for those who are only "enjoying" the leakage from the original performance!

I won't hold my breath on the lighter cable option. Particularly since an adaptor cable is so easily arranged at very low cost. While it may offend the purists, a 2.5- 3.5mm solid adaptor and a mini-jack to mini-jack straight cable would do. Does the extra contact surface of an adaptor ruin the sound of a good headphone? Most seem to need at least one and few would go to the trouble of hard wiring their phones to the equipment. The HD-380 comes with a screw-on adaptor which adds another contact even if the larger jack plug provides greater surface area for a contact in the equipment socket.

Searching online suggests that all-metal micro and mini-plugs are available with much slimmer bodies than the cheap plastic type which I used. The only potential problem here is that the entire length of the plug needs to be slightly smaller than 9mm to fit the cut-out in the headphone earpiece casing. Not forgetting an allowance for the plug location grooves.

I looked into a TV/electronics chain store yesterday and saw a number of cables with much smaller diameter, plastic bodied plugs. Prices were no different from those I paid online. So just looking around locally may save some "waist reduction" of oversized plugs.

Click on any image for an enlargement-