What makes a system sound 'fast?'

Good point Ian. The only live music that's really 'fast' is music played in the open air (like a brass band). Music in a concert hall is always 'slowed down' by reflections arriving at the listener. Luckily, these are generally some dBs down on the direct sound of the instruments.

I had a meeting with Shelley Katz, a classical pianist who's been working on a way to get an electronic piano to sound like a Steinway grand - I mean really sound like it. We did some very interesting experiments and I think he may be onto something. Layered Sound for more information, if you're interested.

I've got more experimenting to do but I'm having fun. It casts some light on the whole floor/stands vibration issue as well.

 

I'd agree about the qualities you describe, but would add that this is not what a lot of listeners who post here think of as fast bass.

Most of the setups I have heard that claim ultra fast bass are actually acheiving this by omission.

The Tact setup I used had, of course, zero overhang unless the subwoofer itself was adding distortion at high levels. Overly dry and anaemic were some of the descriptions along with uninvolving and lack of timing! So I guess the main thing is to get bass that you personally like and don't worry about opinions.

 

As with most things in life I have semi-formed crackpot theory ready for just this occasion:

Lets get one thing out of the way first – IMHO pace has little to do with 'tightness', or the ability to stop the speaker cone. Any decent amp should do this, and many amps that sound incredibly tight and powerful have little in the way of groove or pace which goes a long way to prove my point.

Right, onto the crackpot theory: I reckon it is down to time smear. If you go right back to basics and listen to a seriously competent drummer playing live he can make the same beat sound like it is racing forward or dragging backwards by very minutely changing the relationship between the hi-hat (top frequencies), snare (mid frequencies) and kick drum (bass frequencies). I'm talking tiny, tiny discrepancies in time here – this is the same beat, it would look exactly the same on a musical score, but it can drag or push dependant on the playing technique used by the drummer.

This is incredibly easy to prove on a computer based music sequencer like Cubase or Logic – step write a drum pattern so every beat is in its 'perfect' position, then try delaying or pushing either the hi-hat, snare or kick by a really minute amount – the whole feel of the groove changes.

My theory is that certain poorly designed audio equipment looses or even worse slurs this minute temporal relationship between the high and low frequencies. I don't know how it does this or why, but I am convinced this is what we are hearing and are attempting to describe.

Tony.

 

Tony,

I've no doubt that time smear is responsible, but you must know how drastic the time smear introduced by your listening room is surely?

I can't see any amps being that bad to be honest, and even Sony have seen fit to add a group delay facility to the new digital amps to give some smear in the lower frequencies. People seem to find it more palatable.

 

Yeah it is an odd effect. I used to get that from my old Cambridge A500 amp, the sound actually seemed to get slower, the busier it got. That alone was enough to make me get rid...

 

WM,

That makes even less sense than Isaac's contribution.

FWIW 'damping factor' is a big smoky smokescreen. It's calculated as the ratio of the amplifier output impedance to a nominal 8 Ohm speaker impedance. But the electrical damping is formed by the whole loop impedance including the speaker's internal impedance. The amp makes bugger all difference unless it's truly incompetent or valve. Naim amps have a poor measured damping factor.

Paul

 

But they are bandwidth limited aren't they Paul?

 

The room is a constant in any home dem however imperfect it may be, differences between components are obviously still audible. If I'm right and this 'lack of pace' thing is an artefact of time smear the room must play a less important role than you suspect as products that are poor from a timing perspective tend to be poor in any environment.

If what I think of as time smear is an effect of something measurable and concrete like say poor phase coherence I guess two wrongs may in some situations actually make a right from a system synergy perspective!

I've heard a poor interconnect cable kill the groove stone dead, let alone an amp!

Tony.

 

The room is only a contant with the same kit surely? If you change to something that has a different energy balance the modes will be driven in a different way I would guess.

A 30hz tone in a 16ft room is going to be smeared across some 30ms, surely that is worse than any amplifier's group delay?

Phase coherence generates superb three dimensional imaging and I find Naim product lacking in this regard. But it cleary times well according to the FE boys.

So maybe something else is at work? Or maybe it's all done by the power of suggestion?

 

What has that to do with damping factor?

One thing about Naims is that the damping factor tends to be constant across their bandwidth.

Paul

 

Nothing really Paul, I was just referring back to my belief that bandwidth limited systems TEND to time better for some people.

 

Interesting comment that - because the one thing that will cause frequency dependent phase distortion (and the associated smearing of transients)...is of course bandpass filtering. So "timing" is actually nothing to do with accuracy ? :JPS:

(Saying a 30Hz tone is smeared across 30ms is an interesting way of putting it - but yes, that's the approx. duration of a full cycle. Technically you need to listen for at least HALF a cycle - i.e. 16.7 ms - to actually identify its frequency, and this also goes back to RdS's comment way back that low bass is actually never 'fast'. I do actually agree with your contention that an all too common solution to this pursuit of 'fast' bass is to just throw away what's real that you don't like)

 

The human hearing system is extremely good at distinguishing direct and reflected sounds. If it weren't, we would never be able to follow a conversation in a crowded room.

I have heard a Naim/Dynaudio system do spectacular 3D imaging. It wasn't very nice to listen to though.

 

Chris, it wouldn't work very well if we all spoke in monotone below 50hz

 

Then it's just as well that we don't

I'm not convinced about this argument that a full range speaker (down to 20Hz) will sound slow. My system goes down to 20 Hz and it doesn't sound in the least bit slow. On the other hand, when I had the ATC SCM12s on demo, they sounded slow with or without the sub. My Mission 773es went lower than the ATCs but they didn't sound slow. In fact, the 773e is capable of considerable groove. As are my Castles

 

Chris,

I'd agree with you fully, I'm sure I would not notice anything slow about your system.

But the FE boys would no doubt consider a pair of Castle floorstanders, Arcam CD player and a sub just had to lack PRAT or whatever. I am just pointring out that there are differing interpretations of the word fast, as everything else in this hobby

 

I don't think that type of solid state output device(s) used really makes a difference at all, whether in terms of how "fast" an amp sounds or in any other aspect of its sound.

I'm not saying they all sound the same but there are no typical sonic characteristics of MOSFETS vs. JFETs or any other solid state output device.

When was the last time you heard anyone say "It really sounds like a MOSFET amp" ?

Michael.

 

Actually Michael, I 've heard it said quite a lot and usually the smug git is right!

 

Me too. I'll take slightly flabby, uneven bass over no bass any day

 

I really need to hold a bake-off. Those flat-earth weenie boys are in for a shock :torkmada:

:lol: