AbsoluteAudioFan
Conectat la: 12 Mai 2003
Mesaje: 1203
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 Trimis: Mar Dec 23, 2003 2:26 pm Titlul subiectului: Sunet la volume ridicate |
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Initial am dorit sa pun aceste extrase de pe un alt forum (audioasylum) la Ce spun altii... Avand insa in vedere posibilele dezvoltari pe care acest subiect le poate avea, am considerat corect sa creez un topic nou.
Cineva si'a pus o intrebare banala, insa lipsa de detalii a fost evidenta...
| rob132 a scris: | | I have an amp that puts out 250 watts into 4ohms and speakers that are 91db with a 4 ohm load. At high volumes, the sound becomes harsh and congested. I am trying to find out is this possibly due to power problems or room problems. Any help is appreciated. |
... lucru care a condus la o serie de interpretari, amintindu'se:
1. limitarile boxelor (una dintre cele mai pertinente pareri):
| morricab a scris: | | I saw a report (trying to remember where) that showed for most speakers dynamic compression sets in much earlier than one would expect. For example it is understood that when an amp doubles in power the loudness goes up by 3db...in theory. The measurements I saw in this report showed that for an average sensitivity (87db) two way speaker this was not the case. Up to about 95db the increase with a doubling of power was only a little over 2db and above 95db was only about 1.5 db!! This was compared to a Klipschorn which maintained a 3db increase to over 120db. The other problem is that with a multidriver system (anything from two-way on up) the dynamic compression of each driver will be different unless the designer has taken this carefully into consideration (most likely not). So at high power perhaps the tweeter compresses less and therefore gets louder relative to the woofer or midrange which is already heavily compressing the sound. Then the sound would get very shrill as the tweeter takes over the sound signature. The other possibility is that the tweeter has relatively low power handling for a linear response and is distorting all to hell at high levels (remember most distortion measurements are made usually putting only one watt into the speaker). If your speakers sound lifeless at lowlevels this is because the dynamic response of the woofer and tweeter are different at this low level also. Perhaps the woofer can't get moving well at low levels and the whole sound collapses as a result (very typical I would say for most normal dynamic speakers). Most conventionally designed speakers I have heard sound as they were intended only in a very narrow volume range (from the mid 80db range to about the mid 90db range). Above this they compress and distort and below this they lack the ability to respond to low-level signals. |
Afirmatia acestui tip se potriveste ca o manusa pt. boxele mele, mai putin pt. cele de la micro-sistem  . In cazul acestora (de compresie) sunetul este de exceptie la volume mici si f. mici (prefer micro-sistemul in cadrul asa numitului night listening). Sunetul este OK, si se pastreaza constant, totusi pierzand treptat putin din bas relativ la medii, pana pe la -10dB si peste!!! (volum digital pe micro-sistem...).
Revenind la cele mari, de podea, la volume reduse (sub -48dB - volum amp) basul este subtirel (cele doua drivere asteapata mai mult curent), la volume medii inaltele preiau treptat controlul, la volume medii spre mari (peste -25dB) sunetul se schimba substantial (devine cu atat mai agresiv cu cat sunetul este mai aglomerat, indiferent de genu' muzical), iar la volume f. mari (peste -10dB), pe langa rezonantele cabinetului (e cam greu sa le prinzi de podea, iar boxele nu au tratament interior absolut deloc) apar si distorsiunile de clipping ale ampului. Asta daca excludem camera, care se manifesta naspa de la volume medii (peste -32dB)...
2. relatia amp-boxe:
| Todd Krieger a scris: | Another part deals with an amplifier's ability or inability to handle dynamic swings in a linear fashion, while driving a complex speaker load. Speakers as mentioned are not linear devices, but an amplifier than can handle the varying loads of the speaker will make the amp-speaker combination behave more linear than with an amp with less capability. For I have heard speakers that sound like they compress dynamics with one amp, but not so much with another.
Yet another part deals with non-linearities in amplifiers due to the limited power available from the AC mains. I think this is often why lower-powered amps through efficient speakers sound more-dynamic than higher-powered amps through less efficient speakers, or even though the same efficient speakers. One of the best systems I've heard was a 1.5 watt single-ended amp driving 100dB efficient speakers- I've never heard such effortless dynamics from a system whose amps were rated at over 20 watts a side. |
3. camera si/sau amplasamentul boxelor in aceasta:
| PhilNYC a scris: | | ...the room or the placement? Even if you've had other amps/speakers sound good in this room doesn't mean that every quality amp/speaker combo will sound good in the same space. And you might be surprised at how much even an inch in speaker placement can make on the quality of sound. Can you give any detail about your room, your speaker placement, etc? |
Ca o paranteza, zic eu, interesanta, pot sa amintesc faptu' ca acum sistemul meu s'a mutat din sufragerie in dormitor, unde volumul real/liber este putin peste juma'te fata de cel din sufragerie - insuficient! Ce credeti: sistemu' suna mai tare in spatiu extins decat intr'unul restrans!
4. raspunsul... urechii la sunete puternice (fara citat  )!
5. (almost) all in one:
| bdiament a scris: | The problem could stem from any number of sources, including your source(s).
If your speakers are relatively close to any walls, it could be reflections that are smearing the signal in time.
If your components are not isolated from vibrations, you could just be amplifying vibration induced distortions.
Either of these will become more pronounced (i.e. easier to hear) at high volume levels.
In an effort to remedy the situation, I suggest a couple of things to try before pondering further monetary expenditure (which may not provide a remedy anyway):
1. If possible, get the speakers away from any reflective surfaces. There is plenty of info out there regarding correct speaker placement. Also, you might want to consider sitting a bit closer to the speakers if you are currently listening from far away.
2. Is your AC power clean? Consider a power conditioner (e.g. Monster makes some relatively inexpensive ones).
3. Are your cables all jumbled up? If so, separate interconnects, speaker cables and AC lines.
4. Isolate your components from seismically induced vibrations. This will be most easily audible when you isolate your source component(s) but the benefits extend to everything including your speakers, electronics, etc.. Check out the link below for a very economical way to experiment with isolation and see if this is where the remedy lies. At the very least, you're going to be very pleasantly surprised by the across the board performance improvments from your current gear. |
btw, informatiile vin mai traziu  :
| rob132 a scris: | | I should have mentioned the equiptment, based on some of the comments. The amp and pre are Jeff Rowland and the speakers are Meadpwlark Blue Heron ll's. I know both are capable of better sound than I am getting and I don't believe the volume I am looking for should be a problem. It falls apart at about 75db. Right now, I feel that I have to change my strategy as I have been throwing money at the problem, without getting results. I have had a number of amp, speaker combinations in the room that played loudly without this problem. My room is 14 X 18X 8. |
Sublinierea (bold) imi apartine...
Lasand la o parte faptu' ca ceva'i rotten in his system, restul asertiunilor sunt OK, si deci demne de citit (imho).
Deseori, cand fac comparatii (si'mi mai scapa si o nota ), tin sub observatie si aceste aspecte (unii revieweri le numesc comportament la micro-macro dynamics in varite conditii).
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Pt. cei ce nu mai revin decat la anu' - CRACIUN FERICIT si LA MULTI ANI! |
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greierasul
Conectat la: 21 Dec 2003
Mesaje: 2493
Locatie: Bucuresti
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| Trimis: Dum Dec 28, 2003 3:15 am Titlul subiectului: |
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Pai nu ar trebui sa te mire toate aceste bottom-lines. Eu am ajuns la concluzia ca nu poti face boxele mai bune deoarece atunci cand trebuie sa creezi un obiect aproape de perfectiune de fapt intrii in detalii care te abat de la tinta.
Practic muncesti degeaba.Intrii in lumea microdetaliilor, ti se deschide un nou microunivers de probleme de rezolvat care de multe ori pot sa strice toata munca de pana atunci. Seamana daca vrei cu teoria fractalilor.
O boxa inseamna Mecanica Fluidelor...ceea ce crede-ma inseamna matematica cu enorm de multe variabile complexe. Idealul de boxa este reprezentata ,dupa mine, de un OPTIM.
Plus factorul uman care este cel mai variabil...azi iti place un tip de sunet, maine te schimbi, depinde de starea sufleteasca.
Un sistem audio Hi-Fi nu se alege pentru o gama larga de conditii de utilizare, ci doar pentru una anume.Orice sistem are randamentul maxim doar intr-un punct. Cum te departezi de conditiile necesare satisfacerii acestui punct maxim al calitatii auditiei apar problemele, calitatea scade.
Poate pare un pic tampita ideea mea de final dar am inceput sa cred ca rolul autosugetiei cum ca se aude super este primordial  ))) si chiar sanatos(ramai cu ceva bani in buzunar)
E oarecum asemanator cu femeile. Poti spune clar diferenta dintre cele urate si frumoase dar nu poti alege dintre frumoase: ASTA este CEA mai frumoasa. |
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