'Fast' and 'slow' speakers - should 'fast' = painful to listen to?

[GregD]

At the recent UK hi-fi show at Whittlebury Hall, Northamptonshire I was in one of the rooms listening to a new and unusual-looking loudspeaker design. It had what looked like a single Jordan metal cone drive unit and a folded U-shaped transmission line. It looked like the cabinet was made of bamboo.

The exhibitor put on some music from the famous Jazz at the Pawnshop CD, but after about a minute of what I thought was too loud and harsh I got up to leave.

The exhibitor asked what I thought. I said the sound was very energetic but quite wearing on my ears. I said I was used to my Harbeth speakers which are always easy to listen too and never fatiguing. His response was that his speakers are very 'fast', whereas Harbeths are 'slow' and don't react to the signal fast enough. Effectively he was saying my discomfort on hearing his speakers was my fault for using the wrong speakers and that his speakers were more accurate and faster.

What is he on about? 'Fast' speakers and 'slow' speakers? Can Alan explain whether this is a true phenomenon or more hi-fi folklore.

Whatever the answer is, I'm sure Jazz at the Pawnshop is not 'supposed' to sound painful regardless of the speakers used.

[hifi_dave]

Fast and slow has nothing to do with being harsh or loud. All Harbeth speakers are what I would call normal, they don't slow the music as some designs do but allow it to proceed at the correct pace.

Some call this 'PRAT' which stands for pace, rhythm and timing. It's not something you can measure, as I understand it but when you hear speakers or any other item in the system which slows the pace, you can certainly hear it.

This ability to produce the music naturally doesn't appear to have anything to do with transient response, dynamics or high frequency response. I have no idea what makes for a pacey, engaging sound but Harbeth do it well.

[Gan CK]

Errm i beg to differ slightly here. While i do agree that Harbeths do the PRAT thing pretty well, they are however, not the last word as far as speed is concerned, esp for headbangers.

From my experience, i do feel to a large extent that 'fast' sounding spks are generally very fatiguing. Examples here include full range spks from Feastrex, Coral & probably lowther, Naim spks generally, Royd spks from the 80s, Mission spks, 1st gerantion Linn Kans & Proacs generally. All these are so called fast speakers that seem to artificially heighten the speed & pace of music making for a very lively, enegetic & turbo charged presentation. And its these characteristics that make the sound wearing to listen to in the long run. In addition, most of these 'fast' spks are usually also quite lean with tipped up highs & that further contributes to fatigue. If you want to see wallpaper peeling off by itself, try listening to Eagles' Hell freezes over or Metallica on a pair of Linn Kans driven by Olive Naim amps at high levels. Blazing speed yes but watch out for bleeding ears too.

Many audiophiles tend to equate speed to accuracy. The faster it is, the more accurate is the spk, fatigue notwithstanding. That's a wrong concept actually. Also, different people have different definition of fast. To a guy who has Active Naim SBLs or Linn Kans, Harbeth will definitely be too slow for him. So which is correct? I'd say this has alot to do with choice of music.

If one listens primarily to rock, heavy metal & hard hitting techno music, then perhaps Harbeth is not the best choice. In fact, it would be a waste to use Harbeth to listen to such music. But if one listens to jazz at the pawnshop, vocals, classical or any type of acoustic music, where accuracy of tone, timbre, musicality & an emotionally involving presentation is key, then Harbeth is totally unbeatable!

Ted Jordan drivers have always used metal cones spun from aluminium which is not ideal IMHO for acoustic music such as Jazz at the pawnshop. Metal cone drivers if not properly damped will have a sort of metallic coloration & or a pronounced peak in the presence range that makes for a tiring listen.

{Moderator's comment: aluminium cones can *never* be properly damped. They can be tamed to some degree but at one frequency or another they will ring as metal always does. That character of metal is used (tuned) by cymbal and bell maker's to great effect.}

[hifi_dave]

If you consider the Linn Kan against the original LS3/5A - both used the same drivers and cabinet but the presentation was entirely different. The LS3/5A is a warm, mellow sound but the Kan is bright, hard and thin, which might give the impression of 'speed' but it's no faster than the LS3/5A. The Kan gets it's 'speed' because the response rises from around 1Khz and keeps on going until the tweeter stops responding.

IMO, it's easy to give the illusion of 'speed' if you have a tilted up response and leave out most of the troublesome bass but this isn't reality or natural. A natural, well balanced but pacey presentation is what we want.

[Gan CK]

Yes perhaps you are right Dave.

A tilted up response will generally give the impression of speed. That's why i mentioned that most of the so called 'fast' spks have exaggerated highs & are also lean in character. And yes a natural, rich, well balanced & music driven pace is what we want & that's what Harbeths are exactly.

I was just playing an old J J Cale & Lee Oskar LP & by no means are my SHL-5s slow.

[A.S.]

I too have never understood what the terms 'fast' and 'slow' mean when ascribed to certain loudspeakers. Nor do I firmly understand what 'rhythm and pace' alludes to. I'm sure that in the minds of some critical listeners they hear something and whatever they hear they ascribe to these adjectives expecting us to comprehend. But it's a secret language that means nothing to me.

Talking in code like this is like visiting the doctor with a UJ infection and using euphemisms to describe parts of your anatomy. He/she can probably guesstimate what you're referring to even if you use the most inventive nouns. But why not use precision (latin or mechanical) words which are completely unambiguous to any professional anywhere on earth and get straight to the point. A standardised lexicon is surely essential to knowledge?

[KT88]

Once upon a time, I paid quite a bit of attention to the audiophile language, but Harbeth speakers have cured me of that. I just finished listening to Vivaldi on my Monitor 30s, run by a 30 year old NAD 3020's pre-amp section and a DIY 15 watt class A power amp. It was bliss, moving me to tears at times.

A typical audiophile would laugh at this set up. I'd love to blindfold that audiophile, have him listen to this system and then watch for the shocked reaction upon removal of the blindfold.

Musical communication transcends the audiophile lexicon.

[coredump]

well, once my friend listen to my setup w Harbeth SHL5, they would attest that the music playback is musical and refine. if one's give a damn to 'soundstage' at nearfield listening, they would vehemently claim the soundstage is spot-on. In other word's, they enjoy the music from the simple setup especially the 'thick mid-range' (if i described it correctly)

for that fast sounding speaker, must be using the paper surrounding (Harbeth SHL is using rubber for better damping?) and high efficiency. usually i would find these speaker forward, thin, analytical.

whenever somebody ask me to make a amateur comments on the setup, usually i would give 'average rating'.. To each his own..

Frankly speaking, some high-end / expensive / sophisticated speaker doesn't appeal to most ppl like Harbeth speaker. some speaker shout at you. some are forward sounding. some have super-scale. Personally, any of the speaker that has shout, forward, super-scale signature, i would move on to others. when i reach home, i'll be relieved to have a simple setup with SHL5

[hifi_dave]

'Fast' or 'slow' is the only way I can describe the presentation of certain products, be they speakers, amps, CD players or turntables. Most play at the correct pace/speed but some products (no names, no pack drill) appear to slow the music down slightly as if the CD player or turntable is running slightly slow. This has nothing to do with a 'bright' or 'dull' sound.

I believe it was Martin Colloms, many years ago, who first came up with the term 'pace, rhythm and timing' to describe this effect when reviewing Hi-Fi products. Since then, he has written many articles explaining and quantifying 'pace, rhythm and timing'.

Harbeth speakers are completely neutral or natural when it comes to pace or speed. They are neither dull nor bright and do not slow the sound but give it to you as it was recorded.

[Labarum]

Slow and fast? I really don't know what that can mean. A turnable can run slow - so the tempo will fall, and so will the pitch. But how can an amplifier be slow? Or a speaker?

I can see that if a speaker does not begin to sound immediately it is excited, and continues to sound after the electrical excitation has ceased it might be classed as "slow". Some organ pipes speak faster than others. But is this the effect meant here? Such slowness would render a speaker so poor as to be unusable.

So also an amplifier given a square wave - does the output rise vertically - 0 to 20v (say) in zero seconds. No, it cannot do that, but takes a finite (if extremely small) time - there can be slow and fast here.

But are these the measurable effects that give rise to the description "slow". I don't think so; and I just don't understand.

[hifi_dave]

I'm no engineer, so I won't attempt to explain it. All I can say is that over many years, I have heard and stocked various items of Hi-Fi equipment which does sound 'slow'. I'd love to give examples but I had better not in this Forum.

For a much better explanation than I can provide, Martin Colloms has often referred to 'pace, rhythm and timing or tempo' in his writings and reviews in several journals. Other technical reviewers have used the phrase over the years. It is well known and accepted.

{Moderator's comment: just because one or many journalists use the term surely does not give the expression credibility does it? Why not explain *in your words based on a lifetime experience* what the devil "slow/fast" means such that the rest of us can grasp the idea and go seeki it out?}

[Kumar Kane]

Slow and fast? I really don't know what that can mean. A turnable can run slow - so the tempo will fall, and so will the pitch. But how can an amplifier be slow? Or a speaker?

Quite right, neither do I ! Would a slow speaker be lagging behind the music produced by the amplifier as time accumulates?! And where would the fast one go to ahead of what the amplifier puts out???? I suspect that fast may well be bright and slow the opposite. But that has been refuted a couple of posts prior.

[Labarum]

For a much better explanation than I can provide, Martin Colloms has often referred to 'pace, rhythm and timing or tempo'

Well here is the start of it:

Pace, Rhythm, & Dynamics
By Martin Colloms Nov 24, 1992

http://www.stereophile.com/reference/23/

I have read it a few times over the years, and still scratch my head.

[A.S.]

It's been suggested that 'fast' may be related to a rising frequency response. But as shown here it may also be associated with a boost in the middle or presence band which could/would/may pull the soundstage forward as shown in the fifth image here*. That could certainly be misattributed to being 'fast'.

*Sorry, I didn't realise that these pictures were not numbered. I'll attend to that.

[jair44]

What does 'fast' mean?

Speed in a loudspeaker is related directly to damping factor applied not only to the cone but the cabinet itself (and maybe even the crossover).

Usually lighter and smaller cones seem to react to changes in rhythm faster or more accurately due to lower mass (and lower damping but that's another issue). A heavier damped cone will respond more slowly to changes in signal than a lesser damped one. Most guitar amps stick to lightweight paper cones for this reason. So why bother with damping? Well if you don't bother then you run the risk of all kinds of distortion and frequency anomalies appearing.

Cabinet resonances can also make a speaker sound slow, not only slow as such, but ill-timed as well. Ill-timed can sound blurred, and blurred can sound slow. This effect becomes critical at low frequencies because they are comparatively slow in the first place.

How many car speakers have you heard that had poor 'timing'? Not many I bet, and the same goes for ghetto blasters and such. Furthermore I can't recall any headphones sounding slow in the same way as the comparatively ponderous loudspeaker can. In these cases the cone material is light and the cabinet resonances negligible. Of course they can't portray lifelike scale and dynamics, but as of 2011 audio reproduction is still a question of significant compromises.

Cabinet resonances also explain why boxless speakers will always sound more responsive to the signal, but once again this comes at a cost. Cabinet resonances become more obvious in relation to the amount of bass the speaker is asked to reproduce. The Harbeth thin-wall cabinet is still the best way of dealing with this, despite some controversy over the use of MDF.

So if you want more speed from a Harbeth loudspeaker then you will have to persuade Alan to use a more 'appropriate' cone material. Right now he (Harbeth) prefers Radial. In the meantime you can experiment with the speaker/stand interface to ensure that the baffle remains as vibration free as it can. You can also experiment with placement to see if that helps, but with the thin-walled cabinet it shouldn't be so critical.

Perhaps it's best to accept that compromises are inevitable and that Harbeth is still the best compromise.

[Pluto]

I too have never understood what the terms 'fast' and 'slow' mean when ascribed to certain loudspeakers

Add me to that list - I have no idea what the terms mean.

If I deliberately wanted to create a "fast" version of some music, likewise a "slow" version conforming Colloms' use of the terms, what would I have to change to get from "fast" to "slow"?

What would happen were we to, say, delay everything below 500Hz by 1mS? This would create a small but possibly perceptible lag in the bass compared to the top end. I wonder if it would sound "slow".

Alan - is this a feasible explanation in a speaker designer's world?

[jplaurel]

Once upon a time, I paid quite a bit of attention to the audiophile language, but Harbeth speakers have cured me of that. I just finished listening to Vivaldi on my Monitor 30s, run by a 30 year old NAD 3020's pre-amp section and a DIY 15 watt class A power amp. It was bliss, moving me to tears at times.

A typical audiophile would laugh at this set up. I'd love to blindfold that audiophile, have him listen to this system and then watch for the shocked reaction upon removal of the blindfold.

Musical communication transcends the audiophile lexicon.

You wouldn't get any laughs from me. A few weeks ago, I purchased a very nice 30 year-old NAD 3140 integrated from the local used shop and, after a quick test run on my bench monitors, hooked it up to my Compact 7ES-3s. I think people would be very surprised how lovely such a simple combination can sound. We even hooked up an old AR turntable and the whole thing made for a very enjoyable listening session. The little NAD is only rated at 40WPC, but it seems a lot more gusty than that.

These old integrated amps are a lot of fun. And I love having TONE CONTROLS and a decent phono stage built right in!

[GregD]

After reading all the other members comments about my original posting here, it occurred to me that what the exhibitor could really have been referring to, may have been that his metal-coned speakers were peaked-up at certain frequencies around which the fastest transients occur.

Listening to the speaker could then draw one's attention to these 'fast' transients over other parts of the music that build more slowly, creating the impression of a fast, pacy sound. That I also found the speaker to be fatigueing is perhaps evidence of this peaking.

[Labarum]

Usually lighter and smaller cones seem to react to changes in rhythm faster or more accurately due to lower mass (and lower damping but that's another issue). A heavier damped cone will respond more slowly to changes in signal than a lesser damped one . . . Cabinet resonances can also make a speaker sound slow, not only slow as such, but ill-timed as well. Ill-timed can sound blurred, and blurred can sound slow. This effect becomes critical at low frequencies because they are comparatively slow in the first place.

The words above illustrate well the problems I have with mixing the vocabulary of the musician with that of the audio engineer.

"Lighter cones react . . . faster"

"A heavier damped cone will respond more slowly to changes in signal than a lesser damped one"

That seems clear enough to me - it is the language of engineering.

But "Usually lighter and smaller cones seem to react to changes in rhythm faster or more accurately" leaves me very uncomfortable.

The rhythm of the music is its pulse or tempo measured by it's metronome mark given in beats per minute. (The Wiki is American.)

http://en.wikipedia.org/wiki/Tempo

I fail to see how the musical tempo and the audio frequency can react in the ways suggested by PRaT when they are at least two orders of magnitude apart - rhythm in beats per minute and frequency in hundreds or thousands of cycles per second.

The most incompetent audio system is well able to follow the fiercest rubato - that's when the musician capriciously departs from the mechanical pulse of the music for artistic effect.

http://en.wikipedia.org/wiki/Tempo_rubato

I could go on, but will leave it there. Engineers should stick to their own vocabulary.

[Labarum]

What would happen were we to, say, delay everything below 500Hz by 1mS? This would create a small but possibly perceptible lag in the bass compared to the top end. I wonder if it would sound "slow".

Doesn't this happen naturally with many acoustical instruments? Those that play lower speak more slowly - they are generally less articulate. A tuba and a bassoon cannot be played as fast at a piccolo or a violin; but composers know this, and so write bass lines that move quite slowly in comparison to the higher parts. Percussive bass beats the problem to a degree - tympani, plucked bass strings, the low left hand in the piano; and the pedal organ illustrates the issue supremely - the pedal line of an organ piece will often be no more that bar after bar of supporting chords with no "tune" at all. A 16ft or 32ft organ pipe does not begin to make it contribution in a hurry.

If a loudspeaker is less articulate at lower frequencies that should not (within limits) be a problem, for the music down there is by nature - slow.

I was once in a cathedral organ loft turning pages for a very talented organist. At the end of the piece he said "That was difficult. I had to advance the time on the solo stop." To explain: The cathedral organ had pipes both sides of the choir(stalls) and a "Nave Organ" on top of a "four poster bed" at the back of the church. This had many powerful pipes (stops) which could be used to put a rocket up the backs of the congregation when they wouldn't get a move in in the hymns. On this occasion the organist wanted to use a particular rank of pipes (stop) in the nave organ to play the solo tune with a supporting accompaniment from the pipes in the choir(stalls). He played the tune with his right hand on one manual (keyboard) and the accompaniment on another manual with his left hand, and on the pedals with his feet. Now the solo stop was many metres away at the back of the church, so for the music was to sound right in the choir(stalls) he had to advance the timing in his right hand by some tiny amount to give the sound waves time to arrive from the back of the church. Incredible skill.

I have sung in concerts in York Minster with the organ behind the choir and a big orchestra in front. Getting everything to hang together with such a large distance between the violins and the organ must have been very difficult for the conductor, the leader of the orchestra and the organist.

But I don't anything like these issues in the "timing" of PRaT. I remain bemused.