What does "Timber Accuracy" mean?

[M Gregg]

Originally Posted by cbdb

How do you know whats neutral? ,Your using your ears so all your doing is getting a sound you like. And thats probably with some distortion ("clean amps are boring")

Well if I say that I went to listen to a brass band and then go home and hear what sounds like a brass band that to me is HIFI..

I'll give an example,

I went to a HIFI convention and it had just opened no one else in the room closed my eyes and listened to an orchestra..and when I open them was shocked to realise the room was not the church hall I had been listening to..that to me is HIFI..and its hard to find these days..I guess that most people including me would not want this experience every day but it creates a lasting memory..the sound of people breathing and their fingers sticking to the violins...

Sorry its getting off topic..so I'll shut up..LOL

Regards
M. Gregg

[MelB]

To me timbre accuracy was explained best in a 1972 article by Russell O. Hamm and I quote:
The basic cause of the difference in tube and transistor sound is the weighting of harmonic distortion components in the amplifier's overload region. Transistor amplifiers exhibit a strong component of third harmonic distortion when driven into overload. This harmonic produces a "covered" sound, giving the recording a restricted quality. Alternatively a tube amplifier when overloaded generates a whole spectrum of harmonics. Particularly strong are the second, third, fourth, and fifth overtones which give a full-bodied "brassy" quality to the sound. The further any amplifier is driven into saturation, the greater the amplitude of the higher harmonics like the seventh, eighth, ninth, etc. These add edge to the sound which the ear translates to loudness information. Overloading an operational amplifier produces such steeply rising edge harmonics that they become objectionable within a 5-dB range. Transistors extend this overload range to about 10-dB and tubes widen it 20-dB or more. Using this basic analysis, the psychoacoustic characteristics stated in the beginning of this paper can be related to the electrical harmonic properties of each type of amplifier.

Now you might kid yourself into thinking that your amp is not overloading however you must listen to things at their real levels to make them seem real as well...........

[rongon]

When musicians talk about timbre, we're talking about how to color the sound of a note to express something, or to make a musical line more interesting. On a guitar (what I play), whether you strike the string with a pick, a fingernail or the flesh of your finger makes a large difference in timbre. Whether you strike the string hard or soft changes the timbre (more odd harmonics, a sharper attack and a quicker decay when you strike it hard). How you press the string to the fingerboard, how you hold your hands on the instrument, how you breathe (???) even changes how you physically make tones from the strings. All these effect the timbre of the sounds you make.

Wikipedia claims that timbre is akin to tone color or tone quality. OK.

I would imagine that a good hifi system would accurately reproduce these performance nuances, without changing them. They would bring them to you as the microphones were able to capture them.

So, as usual, the system with the lowest distortion should do the best job of recreating the sound of the performance.

The rest is "I like" this kind of sound or "I don't like" that kind of sound.

--

I guess I have heard some awful amplifiers that seemed to muddy things up so much that you'd find yourself asking, "Is that a cello, or a bassoon?" But it's been a long time since I can remember something like that. I think that would have been something like a Crown DC-150 driving some kind of Tech Hifi brand-of-the-month speaker. You know, back when you heard an NAD 3020A driving a small pair of B&W's and thought, "Wow, that sounds as good as just about anything else around."

This reminds me of the discussion over "microdynamics." I tried to define it, and failed miserably. I now think that it has something to do with dynamics compression. You hear soft sounds a little louder than they were recorded, so the small "details" are brought forward for you. Of course then the macrodynamics suffer because they are now quieter in comparison. Oh well...

One last thing... The room treatment is probably the last frontier. How can you reproduce the sound of the Village Vanguard and then jump to reproducing the sound of Symphony Hall when your room keeps impressing its sound on everything that's playing? For instance, I put a layer of heavy, inert mass-loaded vinyl under the carpeting in my living room. The sound from the stereo improved noticeably. I had removed a large, stray resonance from the floorboards. So much more could be done, I'm sure.

--

[techbiker]

Originally Posted by MelB

Now you might kid yourself into thinking that your amp is not overloading however you must listen to things at their real levels to make them seem real as well...........

I guarantee you that my Comtech 400 does not overload when driving small pro speakers and a smallish passive sub. The sound that I hear when I turn up the volume does not change in any way (even when louder than a standard rock concert). I don't like to listen to music when it's this loud because I don't want to damage my hearing. Mind you that this amplifier is conservatively rated to around 225 watts per channel (RMS) at 8 ohms.

I also have a pip-lite card that monitors the amplifier and tells me if it gets near clipping or thermal overload. It never has. The fan hasn't even turned on yet lol.

The best plan is to purchase an overpowered amplifier that will not get near clipping when your speakers are driven to the max. Then you won't have to worry about overload characteristics.

[rongon]

What about the distortion of the small speakers and the subwoofer? Small speakers, especially, distort quite a bit when driven to rock concert levels. They certainly compress dynamics.

Actually, a rock concert is a good example. How many speakers does it take to create a rock concert in a small club? Just the guitar player probably has more speaker cone area than your entire system. Then there's the bass guitar, and the huge drums people play on these days. Finally, all that is miked up and going through an elaborate PA system, usually tri-amped, etc.

It's a bit much to expect all that to be reproduced by a pair of monitor speakers at true-to-the-original levels (110dB peaks, let's say).

Or maybe not. You might have that figured out. In which case, do tell! How do you do it?

--

[454Casull]

The tree grows straight.

[MelB]

Originally Posted by rongon

It's a bit much to expect all that to be reproduced by a pair of monitor speakers at true-to-the-original levels (110dB peaks, let's say).

Or maybe not. You might have that figured out. In which case, do tell! How do you do it?

--

That's why is use JBL E140's as drivers....

[techbiker]

Originally Posted by rongon

What about the distortion of the small speakers and the subwoofer? Small speakers, especially, distort quite a bit when driven to rock concert levels. They certainly compress dynamics.

Actually, a rock concert is a good example. How many speakers does it take to create a rock concert in a small club? Just the guitar player probably has more speaker cone area than your entire system. Then there's the bass guitar, and the huge drums people play on these days. Finally, all that is miked up and going through an elaborate PA system, usually tri-amped, etc.

It's a bit much to expect all that to be reproduced by a pair of monitor speakers at true-to-the-original levels (110dB peaks, let's say).

Or maybe not. You might have that figured out. In which case, do tell! How do you do it?

--

Well, I'm housing an 8" celestion pro audio woofer in each of my two JBL HLS810 cabinets. 94 db efficiency rated for 100 watts RMS

Celestion TF0818 8" Professional Speaker 150W 294-2060

Combined with a Pyle Pro horn and PDS442 compression driver in each for highs. 105 db efficiency rated for 500 watts (this is overly optimistic)

I'm using a Paradigm SB-90 subwoofer. Not sure of its power handling characteristics.

Needless to say, I can make my system painfully loud in my smallish room. These drivers are designed for pro audio environments (aside from the sub) and are built to play very loudly without distorting! I have not measured the sound levels, however if I were in a real concert that was this loud, I would demand my tickets back.

[kevinkr]

Guys I'm compelled to ask what this thread has to do specifically with designing/building/improving tube amplifiers? I think it needs to be moved elsewhere. Once I figure out where it belongs I am going to move it.

[devilsindetails]

Originally Posted by rongon

.One last thing... The room treatment is probably the last frontier. How can you reproduce the sound of the Village Vanguard and then jump to reproducing the sound of Symphony Hall when your room keeps impressing its sound on everything that's playing? For instance, I put a layer of heavy, inert mass-loaded vinyl under the carpeting in my living room. The sound from the stereo improved noticeably. I had removed a large, stray resonance from the floorboards. So much more could be done, I'm sure. --

+1