DIY akustièna ureditev sobe

[benma]

[raptor]

Znanec je dal skoraj 3 tisocake za zvocno izolacijo (ene) stene, ki si jo deli s sosedom in pravi, da je slusne razlike nekje 10-20%...ce ni soba v sobi je nekako brez veze.

[Solist]

[gerchy]

[joztom]

Takole proizvajalec navaja postavitev na podobni konfiguraciji, le z manjšim (8½) wooferjem, visokotonec in rez sta enaka. S 116dB peak SPL soseda ob pretiravanju zlahka zavrneš.

Evaluation
In common with other EV products, the Sentry 100As come with a cogent, yet exhaustive 'no nonsense' information sheet, illustrated with graphs, diagrams and tables, plus a very readable survey of ideas involved in the design, and some guidance on achieving best results:

1) Use the Sentries in a ¼- or ½-space environment. This means mounting the speakers either flush with the wall, or in a corner, and also near to the floor or ceiling, if convenient.

2) Mount the Sentries so the distance between them is slightly greater than the distance between your listening position and the imaginary line between your listening position and the imaginary line between the speakers. For instance, if the distance between speakers, measured from the centre of each is 8 feet, then you should sit about 7 feet away, angling the speakers accordingly. The result, an equilateral triangle, means the on-axis sound reaches the ears at an overall 60 degree angle, which is generally agreed to be optimum for stereo.

Initial listening confirmed the exceptionally smooth, (if slightly 'hot') bass sound that EV are renowned for. The bass also goes deep, the mean bass SPL being only 3½ dB down at 50Hz (in ½-space), or 3dB down at 40Hz if you take a different average SPL. Cone bottoming (a flop or crack sound) when driving hard below 100Hz is a natural tradeoff with small drivers in vented enclosures, and the Sentries are well above average in this region, as proved by their ability to handle very low notes on DX7 synth, without any distress at high levels.

The dynamic characteristics of the Sentry 100As were equally interesting. It's perhaps not generally realised that many speaker parameters alter radically and unpredictably as the voice coil approaches its maximum excursion and temperature. These effects were manifest in the Sentry 100As to a more stylised degree than is usual, the variation in this instance being potentially very useful.

At low levels, the overall effect is smooth, even soft, and yet not unlike a Tannoy sound, whereas at higher levels, a harder sound, classically attributed to JBL monitors develops. So, in effect, you get three monitoring sounds in one package (the most natural, neutral sound occurring at about 10dB below full power) which is helpful for the purpose of making approximate crosschecks along the lines of "I wonder how this would sound on Tannoys?"

These dynamic effects revolve largely around slight changes in the low midrange (ie. understatement at higher levels), also a slight harshness arising in the low treble when driven hard. However, we found the latter effect could be largely circumvented by turning down the top-end control slightly. Despite this setback, the tweeter is one of the best rock 'n' roll dome designs yet, with perhaps only the Scanspeak (which coincidentally appeared in December HSR's Kord speaker review), the Dynaudio, and a handful of others as potential rivals. There was no evidence of thermal compression (viz. top end balance shift at high SPLs) and regardless of the 2kHz crossover point, neither was there any evidence of the 'honk' or 'rasp' which commonly signifies a tweeter being driven below its favourite band of frequencies.

Stereo imaging was stable, though at high SPLs, it was best to move backwards to, say, 10 or 12 feet, with 6 to 7 feet being optimum at lower levels in an average room. In fact, positioning for optimum stereo was critical, but once you find the right place, the sound stage 'clicks' into focus and becomes very spacial.

Anechoic sensitivity is average for a Thiele design of this size, at 91dB SPL @ 1w @ 1m, but power handling for musically significant periods (over 10 milliseconds) is sensibly quoted at 300 watts (more on this in a moment), so peak SPLs of 116dB at 1 metre are available. However, this relates to anechoic space, and in the ½-space of a real control room, you can add 6dB, giving 116dB SPL short-term at 6 feet.

Power Ratings
Speaker power ratings are a highly confusing area, and the topic deserves further exploration in our 'Control Room' series. For the moment, we'll stick to the observation that EV rate their drivers according to precisely defined, if rather obscure tests. The upshot of all this is that the data sheet tells us '30 watts long-term average PHC' (power handling capacity), and '300 watts short-term (10ms) PHC', both ratings being for 40Hz and above (which incidentally confirms the near impossibility of bottoming the cone at all but the lowest frequencies). Neither figure relates directly to ratings given by other manufacturers - they all differ! However, for practical purposes, the long term (30 watt) rating means the speaker will withstand clipping and overdrive at this power level.

Rated according to the methods of other manufacturers, the PHC would be quoted at between 50 and 150 watts, but what really matters is the short-term PHC, for this broadly indicates the optimum amplifier power, in this instance 300 watts, so, the amp can't readily run out of steam, and go into harmful clipping, before the speaker itself is pushed to its limits, and begins to distort and compress. Put simply, you will get best results from the Sentry 100As by using an amp rated at around 300 watts.

The nominal impedance of the Sentries is a rather unusual (if honest) 6 ohms, which means that on an amplifier rated into 8 ohms, you'll achieve about 30% more power ie. a 300 watts into 8 ohm amp will give around 400 watts into 6 ohms. All this is nothing to worry about, providing your amplifier can drive down to 4½ ohms. This is the minimum impedance, occurring at 45Hz and 150Hz.

Thiele enclosures generally involve a very sharp rolloff at the bottom end, and akin to active crossovers, the curve, or Thiele alignment is characterised by the same terminology: It's a B4, rolling off at -24dB/octave below 40Hz. Set any higher, this sort of response can sound unnatural, but as it stands, the bass sound passes unchallenged; EV are one of a handful of manufacturers who consistently achieve vital qualities in the bass that other people's speakers consistently lack.

Conclusion
To conclude, the Sentry 100As excel in their directional properties versus frequency, and the top and bottom-end performance at high levels. In other respects, individual parameters may be unspectacular, but they're certainly balanced, thus the sum of the ingredients is altogether of a higher order.

These are the speakers to use when you're prepared to sacrifice a little frequency response flatness in return for a slight, but audible increase in the maximum SPL. Rack-mounted, they're also ready in an instant to go out on the road - just slip on the protective grilles. To some users, the changes in the sound at various levels could prove a nuisance, but listen for yourself before buying - we think you'll find the dynamic effects valuable.

Last but not least the 25 watt tweeter is one of the few (nearly!) blowout-proof units around, so if you're having problems in this area, consider the Sentries, but do be sure to treat them to a suitably powerful amplifier.

[Solist]

[benma]

[Solist]

[ambasador]

Dipol zvoèniki vnašajo bistveno manj energije na basu. Nadalje glasnost linijskega izvora zvoka z razdaljo upada 2x manj kot toèkovni izvor. Linijski 3dB z vsako podvojitvijo razdalje, toèkovni s 6dB - tako za slišat iste decibele na kavèu rabi panel polovico manj glasnosti na izvoru (za 2m razdalje od zvoènika). Za veèje razdalje pa še manj.

Prikladna izbira v blokih je torej izbira zvoènika tipa Magneplanar. Omogoèa najmanj 6dB višjo glasnost poslušanja preden se sosedje zbudijo. Poleg tega bistveno bolj izkljuèi akustiko prostora iz zvoènega dogajanja in bistveno manj draži resonance na basu. 'Strelja' base samo naprej-nazaj, niè pa gor-dol in levo-desno. Tako je strop (in tla) zavarovan pred moènimi direktnimi tresljaji in tudi dodatnimi odboji, ki jih je biistveno manj.
Masa membrane je izredno mala - v primerjavi klasièni woofer trese tudi svoj 'box' in èe to postaviš na konice, še dodatno vnašaš vibracije v strukturo hiše. Klasiène zvoènike je v takem bolje postaviti na primerno mehke gumice.

Èe obožuješ zvoènike ki jih trenutno imaš, ti to ne pomaga prav niè. Morda bo pa kateremu od drugih, ki to berejo, prišla prav ta informacija.

Ker je optimalna razdalja dipola od zida izza njih ca 1,3m, bi v tvojem primeru prestavil desno knjižno omaro simetrièno na levo stran okna; kavè pa nasproti okna. Tako bi pridobil akustièno simetrijo okoli okna, ga izloèil kot motilni element in pa pridobil dovolj odstoja od prednjega zida (okna) za Magneplanarje. Taki zvoèniki brez problema stojijo blizu boènega zidu, tako da ti nebi zastirali svetlobe.
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Carpe Diem

[benma]

[ck]

Solist

Zdajle ko bodo trgovine z gradbenim materialom odprli, pojdi po 2 paketa trde kamene volne, nabavi še nekaj zimskega vrtnarskega filca in širok rjav selotejp Tessa. Cena skupaj cca 70€

Naredi quick & ditry variante absorberjev in si jih postavi v sobo po kotih, za zvoèniki,.... Vzelo ti bo 1-1,5 ure.

Pa vsedi se preden daš muzko, da ne boš dol padu od razlike v zvoku.

No ja malce karikiram ampak v glavnem ugotavljam, da se tule vse preveè govori in premalo dela.
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LP

[Tma]

[Solist]

Ambasador hvala za nasvet. Magneplanarje poznam, nisem pa vedel da imajo tudi cenejše modele. Zaenkrat bom še uporabljal EV, si bom pa definitivno zapomnil za v prihodnje.

Ck, kamena volna odpade. Vem da je absorbcija odlièna ampak zaradi vlaknaste strukture ni najboljša stvar za imet v stanovanju. Eden izmed pogojev da je sploh dovoljena uporaba, je da se morajo vlakna v doloèenem èasu razgradit v pljuèih.

Boljše da se malo veè govori, kot pa dela z prazno glavo.

Trenutno berem èlanke o uporabi poliuretanske pene. Absorpcija zvoka je v tem primeru odvisna od debeline same pene, velikosti, strukture in števila por. Struktura ki boljše absorbira nizke frekvence ima probleme z višjimi in obratno. Dodatno se da poveèat absorpcijo nizkih frekvenc s tem da se ustvari zraèni žep, z odmikom absorberja od stene.

Kadar konèam z branjem o poliuretanski peni se bom posvetil melaminski peni, tako da bo ta stvar trajala še nekaj èasa

Vem da "kompliciram", ampak raje nardim stvar enkrat tako kot se spodobi, da imam potem za nekaj èasa mir v glavi.

[ck]

Beri, beri. Še veliko je tega kar moraš obvezno prebrati.

Kar se pa kamene volne tièe, pa verjetno z njo nisi mislil igrati fuzbala, ali paè.
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LP

[berni]

Èe noèeš kamene volne, ki se jo zelo lepo da "zapreti", da ne spušèa majhnih delcev, pa poglej pod Basotect material.
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Lp
Bernard
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Live and let live.