[west]

Congestion can be a subjective term in audio ... if we allow it to be. I
noticed that many types of equipment (amp or preamp, commercial or diy) will
produce a pleasant rendition with simple, chamber type music. OTO complex
passages can collapse the soundstage causing unacceptable distortion. I'm
not saying louder passages, but more complex passages. The amplifier's power
capability and speakers' efficiency have been eliminated in my frustrating
search for the culprit. The opposite type quality is delineation.When
complex passages are playing with delineation and air around each
instrument, it has to bring a smile to your face. Generally speaking, from
limited experience, what in your opinion causes this terrible congestion and
how can we try to prevent it in our designs? Can it be as simple as needing
a beefier power supply? All comments most welcomed. Thanks.

west

[Eeyore]

west wrote:

Congestion can be a subjective term in audio ...

Can be ?

It's very obviously a subjective term. Can you expalin what you mean by it ?

Graham

[Patrick Turner]

west wrote:

Congestion can be a subjective term in audio ... if we allow it to be. I
noticed that many types of equipment (amp or preamp, commercial or diy) will
produce a pleasant rendition with simple, chamber type music. OTO complex
passages can collapse the soundstage causing unacceptable distortion. I'm
not saying louder passages, but more complex passages. The amplifier's power
capability and speakers' efficiency have been eliminated in my frustrating
search for the culprit. The opposite type quality is delineation.When
complex passages are playing with delineation and air around each
instrument, it has to bring a smile to your face. Generally speaking, from
limited experience, what in your opinion causes this terrible congestion and
how can we try to prevent it in our designs? Can it be as simple as needing
a beefier power supply? All comments most welcomed. Thanks.

west

Usually, congestion is the manifestation of high intermodulation
distortions.

And usually, if the THD measurement just below clipping is less than
0.1%,
there isn't much IMD, so no conjestion, and you don't have to force a
teaspoon of lousy tasting cough medicine into the RCA inputs of the
equipment.

It only takes one crook preamp tube to make things sound bad.

As one ages ones ears change their abilities southward.

But if things are bad as you say, and you are noticing distortions,
then to an expert they may be quite appalling. something could simply
be faulty somewhere and in need of a tech.
I have heard guys say "I think I have a little hum..."
and when I go around to see them, I can here the hum before I get
out of the car and go in the house to listen.

Patrick Turner.

[Ian Bell]

west wrote:

Congestion can be a subjective term in audio ... if we allow it to be. I
noticed that many types of equipment (amp or preamp, commercial or diy)
will produce a pleasant rendition with simple, chamber type music. OTO
complex passages can collapse the soundstage causing unacceptable
distortion. I'm not saying louder passages, but more complex passages. The
amplifier's power capability and speakers' efficiency have been eliminated
in my frustrating search for the culprit. The opposite type quality is
delineation.When complex passages are playing with delineation and air
around each instrument, it has to bring a smile to your face. Generally
speaking, from limited experience, what in your opinion causes this
terrible congestion and how can we try to prevent it in our designs? Can
it be as simple as needing a beefier power supply? All comments most
welcomed. Thanks.

west

Most likely culprit is room acoustics.

Ian

[Iain Churches]

"Patrick Turner" wrote in message
...


west wrote:

Congestion can be a subjective term in audio ... if we allow it to be. I
noticed that many types of equipment (amp or preamp, commercial or diy)
will
produce a pleasant rendition with simple, chamber type music. OTO complex
passages can collapse the soundstage causing unacceptable distortion. I'm
not saying louder passages, but more complex passages. The amplifier's
power
capability and speakers' efficiency have been eliminated in my
frustrating
search for the culprit. The opposite type quality is delineation.When
complex passages are playing with delineation and air around each
instrument, it has to bring a smile to your face. Generally speaking,
from
limited experience, what in your opinion causes this terrible congestion
and
how can we try to prevent it in our designs? Can it be as simple as
needing
a beefier power supply? All comments most welcomed. Thanks.

west

Usually, congestion is the manifestation of high intermodulation
distortions.

Yes. That´s my experience too, but also the amplifier has to have
enough power to handle the dynamic of the music being reproduced.
Inability to do this might make the amplifier sound constricted. One
cannot expect a pair of EL84s to sound like a pair of KT88s at a
realistic listening level.

Certain amps sound better with certain speakers in certain rooms.
So any one, or any combination of these three, may be to blame.


And usually, if the THD measurement just below clipping is less than
0.1%,
there isn't much IMD, so no conjestion, and you don't have to force a
teaspoon of lousy tasting cough medicine into the RCA inputs of the
equipment.

It seems to me the THD fig is not so important as the
spectral content of the distortion which goes to make up the THD,
which may explain why to many people two amps which appear to
have a similar specification may sound different to some people.

Even at 0.1% a tube amp with mainly 2H may sound very
good indeed, while an amplifier of similar performance with a
greater content at 3H may prove to be disappointing. (Now
we are back to the pentode vs triode discussion)

2H being at exactly at one octave above the fundamental is not
terribly intrusive on music or vocals although it does sound odd
on spoken word.

3H on the other hand is almost a 5th from the fundamental -
interestingly jangly, especially when the amplifier is trying to
produce a moment in the music based on a diminished or augmented
chord in which the 5th is not found.


But if things are bad as you say, and you are noticing distortions,
then to an expert they may be quite appalling.

Hmm. This is a bit of an enigma. Does one trust the hearing
of a younger person with greater sensitivity and bandwidth or the
hearing of an older, more experienced listener? I find I often notice
things that younger people do not, because I know what to
listen for:-) In a straight audiogram test, they would probably
leave me standing.

Can it be as simple as needing
a beefier power supply?

Interesting point. I have built copies of classic amps
from the 60s (when iron was cheap and large electrolytics
*very* expensive) and greatly stiffened the psu with
capacitance of an order of magnitude greater than in the
original. The psu "sag" was measurably better on pulse
testing, when driving the amp hard, but neither I or
any of the other people listening were able to hear
any improvement at normal level.


All comments most welcomed. Thanks.

Just my 2 cents, West:-)
Regards
Iain

[Peter Wieck]

Note the interpolations:

On Apr 19, 10:35 pm, "west" wrote:
Congestion can be a subjective term in audio ... if we allow it to be. I
noticed that many types of equipment (amp or preamp, commercial or diy) will
produce a pleasant rendition with simple, chamber type music. OTO complex
passages can collapse the soundstage causing unacceptable distortion.

Certainly. Such music is typically not terribly dynamic and typically
has a very low peak-to-average. There is but so loud one might go with
a stringed instrument greater than its average volume. Exceptions
exist, certainly, but most chamber music utilizes few instruments at
moderate volumes. No surprise there at all.

"Complex passages"... May I take that to be "louder" passages, or do
you simply mean where more instruments are playing and/or the same
number of instruments are playing more notes? Bach's two-harpsichord
concerto certainly gets complex at times, but not terribly loud. A
system capable of producing the 'quiet' parts should do just fine on
the complex parts all other things being equal. And you have to be
very, very, careful when you exclude "louder" when defining "complex".
If you were to measure the output levels, it would be a fair bet that
the complex passages are also putting out more energy. Please let us
know if you have actually measured these voltages.

I'm not saying louder passages, but more complex passages.
The amplifier's power capability and speakers' efficiency have
been eliminated in my frustrating search for the culprit.

Are you sure? Just some thoughts:
a) A 3dB increase in volume takes 2X the power. A 10dB increase in
volume (as you perceive it 2X as loud) takes 10X the power. So an
amplifier ticking along at 0.3 watts needs all of 3 watts to make 2X
the volume. Next step is 10 watts. And that is for a peak-to-average
of 20dB.
b) Horn-type tweeters, and conventional driver full-range single-
driver systems are notoriously directional and have a very limited
'sweet-spot'. Furthermore, this same sweet-spot is highly affected by
room dynamics. One might "lay out" the system following all the
"Rules" and get not much more than mud simply because something else
is going on in the room that does not follow those rules. Standing
waves come to mind as very common, frequency-dependent phenomenon not
commonly understood or recognized.
The
opposite type quality is delineation.When
complex passages are playing with delineation and air around each
instrument, it has to bring a smile to your face. Generally speaking, from
limited experience, what in your opinion causes this terrible congestion and
how can we try to prevent it in our designs? Can it be as simple as needing
a beefier power supply? All comments most welcomed. Thanks.

Too much else going on to give a simplistic answer. What won't happen
is a solution through wishful thinking and without understanding the
entire system from the carpet (if any) on the floor to the quality of
the recording. But as a start, go through the process of elimination.
Start with the really simple stuff, like listening to those same
troublesome passages through headphones. Typically a standard dynamic
headphone will take vanishingly little power and allow even the most
anemic amp to do just fine. A very good pair of headphones will be
brutally revealing as well to any sources of noise or distortion. So,
if the troublesome passages clear right up through headphones, you
either have a room acoustics problem or a headroom problem, or a sweet-
spot problem or some combination of all three. Or, worst of all a
crappy-speaker problem. And by that I mean simply not suited to those
electronics. Not necessarily intrinsically crappy... that would be
another discussion.

If it does not clean up, then you have an electronics problem or a
source problem (the quality of the recording). Try another power-amp,
try another pre-amp, try running the CD player directly into the power-
amp on the presumption that either has a level-control. If you are
running from vinyl, you may have a tracking and/or cartridge problem
or a loading problem between the cartridge and the pre-amp. It has
been my experience that perhaps 60% of all vinyl users run their
tracking force between 50% and 75% low, on the highly mistaken
assumption that less force preserves the records better. And also, you
may be experiencing acoustic feedback if you are sourcing from vinyl.
This is a VERY simple test. Let the stylus sit on the record not
moving. Turn the volume about 3/4 up. If you get feedback, then you
need to isolate the platter better from the speakers. And that would
absolutely muddy any highly complex passages with your speakers and
otherwise electronics being faultless. Note that feedback will not be
an issue through headphones, hence the statement above "source
problem".

And, of course, one really silly but awfully common mistake that
results in considerable mud: Are your speakers in phase?

west

A good question, but as usual, you leave out a lot of useful
information. What equipment are you using? What is the source? What is
the room? What is the music? How is it all placed?

Peter Wieck
Wyncote, PA

[Arny Krueger]

"west" wrote in message
news:rFVVh.7683$xP.3845@trnddc04...

Congestion can be a subjective term in audio ... if we allow it to be. I
noticed that many types of equipment (amp or preamp, commercial or diy)
will
produce a pleasant rendition with simple, chamber type music. OTO complex
passages can collapse the soundstage causing unacceptable distortion. I'm
not saying louder passages, but more complex passages. The amplifier's
power
capability and speakers' efficiency have been eliminated in my frustrating
search for the culprit. The opposite type quality is delineation.When
complex passages are playing with delineation and air around each
instrument, it has to bring a smile to your face. Generally speaking, from
limited experience, what in your opinion causes this terrible congestion
and
how can we try to prevent it in our designs? Can it be as simple as
needing
a beefier power supply? All comments most welcomed. Thanks.

I hear that a lot with SETs. I don't hear it a lot with tubed and SS amps
with enough power and intelligent use of feedback, particularly when hooked
to good, robust speakers.