Zestawy Dunlavy

28 Lipca 2009

Interesują mnie szczegóły konstrukcyjne zestawów głośnikowych Dunlavy.

**Kazik II** · 28 Lipca 2009

Pod tym linkiem jest trochę informacji na temat założeń konstrukcyjnych , w jakimś numerze AUDIO był wywiad z Dunlavym. Dystrybutorem był Pan Jasik z Nieporętu.

**Kazik II** · 28 Lipca 2009

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28 Lipca 2009

Zapomniałem, że kiedyś zapisałem na komputerze jego stronę internetową - niestety już nie istniejącą

Dunlavy Audio - Design Philosophy

About John Dunlavy -

Mr. Dunlavy is a physicist and electrical engineer with internationally recognized credentials and accomplishments. He has spent more than 25 years in the field of high end audio design and manufacture. He has authored books on antenna theory and technical papers to the IEEE, AES, IREE, and holds a significant number of patents in the fields of antennas, loudspeakers, audio and cables. He also enjoys playing acoustic string bass.

Dunlavy's design philosophy -

John Dunlavy believes that a speaker should both sound and measure accurately, and that it's output should mirror the input. To determine a speakers measured accuracy requires a battery of comprehensive tests, many of which audiophiles are unfamiliar with. It also requires a fully equipped laboratory with an anechoic chamber. An anechoic chamber is a reflectionless room, extremely heavily damped, used for measurement purposes only. It allows the room to be ignored leaving only the speakers performance behind. Exotic tests like step response, impulse response, waterfall spectral decay plots, square wave response and phase linearity are measured along with the more common tests like frequency response, impedance, distortion and sensitivity.

All of these tests would be meaningless if the results didn't produce a subjectively accurate and natural sound as well. To that end, John Dunlavy has spent decades correlating these advanced measurements with the sonic outcome. Countless live versus recorded tests have been conducted to determine which tests, specifications and design parameters matter most to the end of reproducing music accurately.

All of the research pointed to this. To accomplish both measured and subjective listening accuracy, Dunlavy speakers must use a time aligned vertical symmetrical array of carefully matched drivers with a calibrated phase coherent crossover in a well damped sealed box. Lets explain this in more detail.

Time alignment means that the vertical plane of the voice coil of the tweeter is in mechanical alignment with the midrange and woofer voice coils. This usually means setting the tweeter back in the cabinet an inch or so because woofers are deeper than tweeters. It also means lining the edge of the grille and baffle area with felt to absorb unwanted reflections off them, as reflections are time errors as well. Without time alignment, the leading edges of transients are blurred as the highs will get to your ear before the bass and midrange will.

A vertical symmetrical array means that in a two-way speaker there is a centrally located tweeter with a matching midrange both above and below the tweeter. In a three-way, a matching woofer is added above and below the midranges, and so on. This doubles the power handling capability and halves the distortion compared to using only one midrange/woofer, as two drivers work half as hard. It also gives a very wide and even radiation pattern for better imaging and soundstaging.

Driver matching. First, all of the drivers are individually tested to make sure they are within the specification of plus or minus 3dB over the range they are intended to cover. Independent tests show that very few speakers on the market actually achieve plus or minus 3dB of error regardless of what they may advertise. Then the drivers are pair matched so that they are all very close to being the same, and consecutive serial numbers are assigned. This makes sure that the left and right speakers sound and measure as close to each other as possible. This provides proper tonal balance and soundstaging.

Without a phase coherent crossover, time alignment becomes less meaningful. All crossovers except one kind "slow down" some frequencies compared to others, negating the advantages of time alignment. Dunlavy uses minimum phase single order (6dB per octave) crossovers to keep different frequencies in "electrical time" with each other. The crossover is then tweaked with different capacitor values to the actual drivers in that particular speaker. This means that the crossover in a Dunlavy SC-1av going down the assembly line is very likely different from the next Dunlavy SC-1av being produced! By doing this custom calibration, Dunlavy is able to halve the error of the already excellent frequency response measurement of plus or minus 3dB and achieve a remarkable specification of plus of minus 1.5dB. Ultimately this means that all Dunlavy speakers sound virtually identical and have exceedingly low coloration or personality.

A well damped sealed box means that there is a proper box size and shape for each individual midrange or woofer with an optimum amount of acoustic sound absorbing material installed. There is no port or hole in the cabinet. This sealed box design means the cabinet has to be larger for the same bass response cutoff than one with a port would have. Unlike a ported design, it's superior damping allows the drivers to start and stop better with the music signal instead of continuing to ring and resonate after the signal has been shut off. Ports also introduce time delay because the sound from the back side of the cone comes out of the port and hits your ear later in time than the sound from the front side of the cone. This is heard as a loss of bass definition or even boominess.

All of the above explains why very few other speaker manufactures even try to make an accurate speaker. The aren't equipped to do so in terms of laboratory test equipment and don't have an anechoic chamber. This is why you will rarely see the measurements discussed above published by other speaker companies. Also most speaker designers are not formally trained engineers. They are hobbyists who have a "sound" they like and want to be in the speaker business. We call this sound "designer coloration". It may sound good to some people short term, but in the long run it fatigues because it is not accurate or natural.

vereker · 29 Lipca 2009

Kazik II, 29 Lip 2009, 00:22

> w jakimś numerze AUDIO był wywiad z Dunlavym.

Końcówka l. 90-tych.

29 Lipca 2009

Ma ktoś te AUDIO z wywiadem z Dunlavym?

29 Lipca 2009

http://www.stereophile.com/floorloudspeakers/162/index.html

http://www.stereophile.com/budgetcomponents/1294dunlavy/index.html

http://www.stereophile.com/floorloudspeakers/166/index.html

29 Lipca 2009

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29 Lipca 2009

Step response - The most important measurement that John Dunlavy felt one could make because it simultaneously encompasses excellent frequency and phase response when properly interpreted. In other words excellent frequency and phase response are implicit in a good step response measurement. On a graph, a step response with accurate properties would have one rapid straight up positive rise in amplitude, with the amplitude diminishing in time at a slow smooth rate. The graph would show this diminishing amplitude by looking like the downward tilt of a mild ski slope. I have never seen a speaker outperform a Dunlavy in this crucial test.

29 Lipca 2009

Impulse response - This correlates with the time alignment and phase coherency of the speaker and shows the lack of or the presence of stored energy and ringing. On a graph, a proper looking impulse response starts at zero and swings up with one rapid positive amplitude spike, coming straight back down with only a small swing below zero before coming back above zero to stay with no subsequent movement or ringing. It's literally a spike up and down again. You will see many speakers whose impulse response starts by going negative, then swings back and forth over zero more than once, and then continue to wiggle on the graph. This indicates poor phase response, time alignment and high frequency ringing. Ringing is common to metal dome tweeters.

29 Lipca 2009

Waterfall plot - This is a measurement of the time it takes the speakers output to decay from a given loud sound pressure level to a much quieter level across the whole audio range. Both the cabinet, drivers and crossovers energy storage and release is shown in this measurement. Bass frequencies take longer to decay than higher frequencies. The faster and smoother the release, the less coloration the speaker is causing. Look for a lot of white space between the top input signal line and the hash below it. The more of the graph floor you can see, particularly in the treble, the better. Dunlavy's measure exceptionally well because of the inherent linearity of their

29 Lipca 2009

Square wave response - You wouldn't want to listen to a square wave as it's a very annoying sound. But it is a useful test. For a speaker to pass a square wave and keep the square wave looking square, it has to exhibit both flat frequency response and be phase and time coherent. Very few speakers at any price can make a square wave look even vaguely recognizable. All Dunlavy's pass the test with ease.

29 Lipca 2009

Frequency response - A perfect speaker would cover the audio range of 20hz-20khz with out exaggerating or suppressing any frequency or tone over another. This is called flat response. On a graph, flat response would be a straight line between 20hz (deep bass) and 20khz (extreme treble). The amplitude or volume of error from flat response is measured in plus or minus decibels. Many popular "high end" speakers exhibit plus or minus 5dB or more of error, often designed in on purpose as "designer coloration". All Dunlavy's measure within plus or minus 1.5dB of flat response over the range that model was designed to cover. Larger Dunlavy models maintain flat response deeper into the bass range than smaller models.

29 Lipca 2009

Impedance vs frequency - A resistor would measure the same impedance at any frequency. All speakers have an impedance that varies with frequency. Unusually low or high values or sharp changes or large swings in impedance can cause your amplifier problems driving your speakers. Your amplifier may run out of current if the impedance is to low or wild in its swing. Also, an amp with high output impedance, particularly a single ended tube amp, may have its frequency response modified to create very noticeable errors to your system. Dunlavy's impedance curves are unusually flat and very easy for any reasonably well designed amplifier, even small tube amps, to drive.

29 Lipca 2009

Sensitivity - The amount of sound pressure level your speaker generates by feeding 2.83 volts of signal (1 watt into 8 ohms) measured at 1 meter away. Dunlavy's measure between 90 and 91dB sensitive which is well above the average of 88 or 89dB. This is important because for each 3dB loss of sensitivity, the amplifier power has to be doubled to the speaker to keep the volume level the same. This means Dunlavy's don't need a large expensive amplifier to play at realistic listening levels.

Distortion - The presence of signals in the output of a speaker not present in the input. Since distortion in even the best speakers is many times higher than the measurements consumers are used to seeing for even medicore amplifers, it is understandable why speaker manufacturers may be reluctant to publish distortion specifications that may be misinterpreted. Dunlavy speakers produce a very respectable 1% THD or less at 90db sound pressure level over the frequency range that model was intended to cover. Harmonic distortion in poorly designed speakers can reach 5% or even 10%.

-Total harmonic distortion (THD) can result from only one input tone. Ie., a 100hz input signal yields 100hz on the output as well as 200hz (even 2nd harmonic distortion) and 300hz (odd 3rd harmonic distortion) on the output. Even several percent 2nd harmonic distortion can actually be pleasant to listen to and is common to many single ended tube amplifier designs. When it gets excessive it can make bass boomy or even shift the pitch up an octave. Odd order THD can add brightness and brittleness to the sound even in small quantities.

-Intermodulation distortion (IM) is a sum and difference mechanism which results when two or more tones are mixed together. Ie., 100hz mixed with 1000hz on the input produces output of 900hz and 1100hz in addition to the input tones. The 900hz and 1100hz tones are then free to intermodulate with themselves and other tones creating even more distortion. IM is harsh and unpleasant to listen to even in relatively small quantities because it is not harmonically related to the input signal.

patefonik · 30 Lipca 2009

Dodać można, że te średniotonowce, albo w monitorach niskośredniotonowce to vifa p13 wh-00-08 ( nie pamiętam czy to się pisało z myślnikami )Bardzo fajne tanie głośniczki o ciepłej barwie chociaż niezaszybkie. Generalnie sam pan D. bardzo lubił te głośniki i kiedyś nawet był gdzieś w necie cały jego artykuł pochwalny na temet tego przetwornika. Podobne monitorki popełnił kiedyś zbliżone konstrikcje na tych przetwornikach ( zbliżone jeśli chodzi o przetworniki )

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