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#1
Posted to rec.audio.tubes
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Congestion
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 |
#2
Posted to rec.audio.tubes
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Congestion
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 |
#3
Posted to rec.audio.tubes
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Congestion
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. |
#4
Posted to rec.audio.tubes
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Congestion
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 |
#5
Posted to rec.audio.tubes
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Congestion
"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 |
#6
Posted to rec.audio.tubes
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Congestion
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 |
#7
Posted to rec.audio.tubes
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Congestion
"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. |