Dayton WT3 manuale d’uso

Online Use r’s Guide Revised: May 1 1, 2008 WT3 is produced b y: Dayton Audio 725 Pleasant Valle y Drive Springboro, Ohio 45066 US A http://www.da y tonaudio.com Copyright © 200 7-2008 by John L. Murphy , Andersonvill e, TN USA All Rights Res erved. No part of this publication may be reproduced without prior exp ress w ritten permission.[...]

Minimum Requir ements for the PC The minimum requireme nts to run WT3 are: • A PC with a processor runni ng at no less than 500 MHz wi th 64 MB RAM • One available USB port • A display with resolution of at least 800 x 600 pixels WT3 runs under Microso ft Windows 98, Me, 200 0, XP and VISTA operating s ystems.[...]

Quick St art for the WT3 Woofer Tes ter *** VERY IMPOR TANT SAFETY N OTE *** NEVER conne ct the test leads of the WT3 to a speake r that is connect ed to any other equi pment or to an equipment ground! Seve re damage could occur to the WT3 unit or to the other equip ment. Only connec t the WT3 to an unconnecte d loud speaker. Naturally, you will wa[...]

6) Select “I mpedance Calibration ” under the “Impeda nce Analyzer” menu. The software will sweep the resist or and plot the results. The uncalibrat ed impedance is displayed and the calibrat ion is complete. You should als o calibrate the test leads at this t ime by selecting the appropriate command unde r the "Impedance Anal yzer&[...]

9) Measure the driver's V(as). Once you have measured t he driver's free air param eters the "Measure V(as)" button becom es enabled. Select one of the three meth ods to measure the V(as). Then pr ess the “Measure V(as)” button to start the measurement procedure. The thr ee V(as) measurement methods are: Test Box Method Adde[...]

Window s Vista - Additional Se tup Require ments PLEASE N OTE: STEP 2 IS CRI TICAL FOR WIND OWS VIS TA USER S! 1. Go to the Windo ws Control Panel and open the “Sound” control panel. A t the "Pla ybac k" tab mak e sure that "USB Audio Co dec" is selected as the default sou nd system for playback. (the icon shoul d appear wit[...]

3. Click OK to close the "Sound" control panel. Note that this setup mu st be performed once for each USB port with which the WT3 unit will be used. Also, when starting WT3, always click on the Speaker icon in the task b ar and make sure the W indows Volume Control is s et at maximum .[...]

Introducing W T3 No other loudspeaker par ameter measurement s ystem is as fast or as eas y to use as Dayton Audio’s WT3. WT3 emp loys powerful new DSP measurement t echniques to provide highl y accurate parameters in seconds. W hile previous generation woofer testers t ook around 6 minu tes to measure 30 impedance points, the new W T3 measures o[...]

The WT3 T oolbar The WT3 Toolbar provid es easy access for man y frequently used commands. M emory show and hide operations are especiall y convenient with the toolbar. Note that empt y memories are gra yed out until data is saved to them. Once the y contain data the y become enabled to switch between show and hide modes.[...]

Using the W T3 Memories The WT3 software features 20 user memories for saving your detailed measurements alon g with much other user entered inform ation about the driver. Ea ch memory consists of the impedanc e and phase plots, the test setup i nformation (test box v olume, added mass etc.) along with the t hree pages of parameters, ,specificatio [...]

View Menu: Clear Me mory These commands erase the contents of t he specified memor y. • From the keyboard, use Ctrl+Alt+1, C trl+Alt+2 etc. through Ct rl+Alt+0 to clear the contents of memories 1 t hrough 10 • Use Ctrl+Alt+Shif t+1, 2 etc. through Ctrl+Alt+S hift+0 to clear the contents of memories 10 through 20 For example, to erase the respon[...]

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Frequentl y Asked Q uestions a bout WT3 Q: Why do I h ave to wait 90 seconds for the WT 3 hardware to w arm up? A: The initial 90 second waiting period dela y is required in order for the hardware power suppli es to ramp up and stabilize. To perform pr ecision measurements down to 1 Hz very wide low frequen cy bandwidth is required. Q: My WT3 was w[...]

Removing WT3 from your Comp uter You can easily remove W T3 from your computer’s hard d rive if needed. • Go to the control panel and doub le click on the “Add/Remove Programs” icon • When the Add/Remove dialo g appears, locate WT3 i n the list • Select WT3 and then clic k on the Add/Remove button • When you are asked “Ar e you sure[...]

File Menu The commands under the File menu are as follows: ew (Ctrl+) Clears all current data to creat e a new empt y WT3 project file. Each project file holds up to 20 measurements in individual m emories. The memories can be displ ayed or hidden by clicking the corresponding memor y buttons on the toolbar. Open… (Ctrl+O) Opens a WT3 proje[...]

Import Impedance Data… Opens a file dialog to select a .tx t (or .zma) file containi ng data to be imported to the W orkbench. Within t he .txt file each data point must be on a single line in the fo rmat: “Frequency Impedance Phase” with the frequency, impedance and phase data separated b y a tab or spaces. When the file is opened the data i[...]

Recent Files... A list of recentl y used files is displayed for eas y access. Exit (Ctrl+Q) Exits the application. The ke yboard shortcut is ver y convenient.[...]

Edit Menu The commands under the Edit menu are as follows: Undo (Ctrl+Z) Undo is not impl emented Cut (Ctrl+X) Cut is impl emented for various text fields. Tex t is cut and placed on the clipbo ard for pasting to another location if desired Copy (Ctrl+C) Copy is implemented for various text fields. Cop ied text is placed on the clipboard for pastin[...]

Preferences This command opens the Preferences Dialog (sho wn below) where you can chan ge various printing, measurement and displa y settings Plots can be switched between fine and bold lines separately for displa y a nd printi ng. You can select metric units separatel y for Volumes and other unit s. Auto Ranging is normall y on but can be switche[...]

View Me nu The commands under the View menu are as follows: Toolbar Select the Toolbar command t o alternately hide or show t he toolbar. Status Bar Select the Status Bar com mand to alternatel y hide or show the status bar at t he bottom of the main page. The Status Bar disp lays information for menu it ems and buttons. The Status Bar also shows w[...]

From the keyboard, use Alt+1, Alt+2 et c. through Alt+0 to save to memories 1 throu gh 10. Use Alt+Shif t+1, 2 etc. through 0 to save to memories 10 th rough 20. For example, to save the cur rent response to Memor y 5 you would press and hold the Alt ke y and then press the 5 ke y. Note: The m ost rec ently measured impedance plot is said to resid [...]

Impedance Analyzer Menu The Impedance Anal y zer Menu contains command s for running measurements and for performing calibration of the test lea d resistance and master cali bration as follows: Measure Free Air Parameters This command causes W T3 to run an impedance s weep and then extract the driver's free air parameters. You can also use thi[...]

Impedance Sweep Use this command to per form a simple impedance sweep without the extracti on of any parameters. Driver parameters will be cleared to pr event any confusion. Impedance Calibration. .. When first installed, W T3 is calibrated to within about 2 % for the impedance range under 100 Ohm s. This is adequate for measu ring driver parameter[...]

Test Leads Calibration ... When the software is first i nstalled the default test lead impedance is 0.3 Ohms which is t ypical of the units. Use this comm and to refine the test lead calibration for your WT3 unit. Shown below i s the test leads calibration dialog. Ju st short the test leads and cli ck OK. The software wil l measure the test lead re[...]

Help Menu The commands under the Help menu are as follows : Help Topi cs The complete WT3 User’s Guide can b e found under the Help menu > Hel p Topics. User Information Enter your personal inform ation in this windo w. This is the information that will di splay at the Splash Screen and in the title bl ock of your printed reports. About WT3 Di[...]

Using WT3 to Mea sure a Woofer's P arameters The basic steps to measure a driv er's parameters are as follows. Before starting, be sur e the unit has been calibrated. • Start by connecting the W T3 hardware unit to a USB port on your PC. • Next, launch the WT3 software. • Make sure that the woofer is no t connected to any other equi[...]

Using WT3 to Mea sure a Tweeter 's Parameters A typical sealed back mo ving coil tweeter operates as a ver y small closed box s y stem and therefore can be characterized b y it's closed box resonance a nd Q, F(sc) and Q(tc). You can use WT3 to measure both of these parameters for tweet ers as well as woofers and midr anges. The frequenc y[...]

Here is a typical result wh en measuring a tweeter: We can read the tweeter's resonanc e frequenc y, F(s) (or, more strictly F(sc)), di rectly from the impedance plot or note the value at the M easured P arameters F(s) field. Just as with a closed box, the system's Q(tc) is read from the Q(ts) field. Similarl y for the electrical and mech[...]

Using WT3 to Mea sure a Resistor Before starting, make sur e the WT3 unit has been calibrated and has stabilized for at least 90 se conds. Measure the value of a resis tor as follows: • Launch the WT3 software and make su re the volume is set at m aximum. • Make sure that the resist or is not connected to any other equipm ent and then connect t[...]

at 0 degrees except for a slight rise at the high frequ ency limit. Here the measured value of 9.998 Ohms is seen to closel y match the resistor's specified value of 10 Ohms +/- 0.1%. At full playback volume the "noise" on the measu rement is usually onl y one or two pixels as seen above. Higher noise levels can indicate that the tes[...]

Using WT3 to Mea sure an Induc tor Before starting, make sur e the WT3 unit has been calibrated and has stabilized for at least 90 se conds. Measure the value of an i nductor as follows: • Launch the WT3 software and make su re the volume is set at m aximum. • Make sure that the inductor is no t connected to any other equipment and th en connec[...]

phase response (red) is se en to be near zero degrees at low frequ encies and increases to 90 de grees at high frequencies as expe cted for the simple (R-L) test circuit. The measured value of 0.9893 m H is in good agreement with the indu ctor's nominal 1.0 mH rating. At 0.242 2 Ohms the ind uctor's DC resistance is nicely low a s require[...]

Using WT3 to E valuate a Closed Box Lo udspeaker A closed box t ype of loudspeaker system is characterized b y a resonance frequency F(sc), an electri cal Q value Q(ec), a mechan ical Q value Q(mc) and a t otal Q value Q(tc). Just as you can use WT3 t o measure a driver's parameters you can also use WT3 to measure the corr esponding paramete r[...]

Here is a typical result wh en measuring a single ful l range driver in a closed box type enclosure: By inspecting the impedance plot we c an determine that this is a closed box type of loudspeaker system from the presence of th e single impedance peak in th e low frequency ran ge. From the impedance plot alone we can identify the closed b ox reson[...]

Using WT3 to E valuate a Vented Box Lo udspeaker A vented box t ype of loudspeaker system can be characteriz ed by it's equivalent closed box Q(tc) and the vented enclosure's Helm holtz tuning frequenc y F(b) . You can us e WT3 to measure both of thes e parameters for an y vented box loudspeaker system. The frequenc y response of a vented[...]

Here is a typical result wh en measuring a single ful l range driver in a vented box type enclosure:[...]

In order to read the vent tuni ng frequency, F(b), more precisel y we can adjust the frequenc y display limits to zoom in on the frequency range containing the two imped ance peaks as shown below: At this screen we can determine that F (b), the tuning frequenc y of the vented box , is approximatel y 40 Hz by locating the imped ance minimum between [...]

Using WT3 to E valuate a Complete Speak er System You can use WT3 to measu re the impedance of com plete multi-way loudspeaker s ystems. Based on this impedance curve we can tell a numb er of things about the s ystem, such as whether the woofer u ses a closed or vented enclosure. W hile a single peak in the low frequ ency range suggests a closed bo[...]

Here is a typical result wh en measuring a complet e 2-way speaker s ystem: We can see that this s ystem employs a vented woofer s ystem with the vented enclosure tuned to abo ut 40 Hz. Even with a mini mum impedance of just o ver 6 Ohms this would often be consider ed to be a nominal 8 Ohm louds peaker system.[...]

Using WT3 to Dia gnose Loudspeak er Fault Conditions When carefully applied WT3 can be used to spot common p roblems with a speaker system. For example, the screen belo w shows two impedance measurements of th e same two-wa y speaker s y stem. The green (lower) plot shows t he normal impedance response of this s ystem. The purple (uppe r) plot show[...]

In the screen below you see the same system as above but th is time with a shorted tweeter. The green (upper) plot again shows the normal impedance respons e of this system. The yellow (lowe r) plot shows the system with a shorted tweeter. The s ystem with the shorted tweeter appears to have a suspicious ly low impedance above 4 kHz or so but when [...]

Now let's examine sim ilar fault conditions for the woofer. Th e screen below shows the same 2-w ay system as above with the green plot representing the normal s ystem and the oran ge plot showing the system in a fault mode w ith an open circuit woofe r. The system is seen to be unlo aded (high impedance) over most of t he woofer's freque[...]

Finally, here is a screen s hot showing the same s ystem with the woofer in a short circuit fault condition (lower blue trace). As we see in these examples of ten a system fault is most easil y detected by comparing the suspect s ystem to a known good s ystem.[...]

Using WT3 to De sign a Zobel Netw ork Zobel networks are used to control the impedance of a loudspeaker drive r in the upper frequenc y range where voice coil inductance normall y causes the impedance to ris e with increasing frequenc y. Zobel networks are used to help crossov ers do a better job of keepin g the highs from passing to the woof er. A[...]

we can get it in the upper frequency range. Let's start with around 1 uF for the capacitor and s ee what we get for a new impeda nce response. The screen below shows the new impedanc e response in purpl e with the original (uncom pensated) response in blu e. Notice that the impedance has onl y been reduced above 5 kHz. This is bec ause our cap[...]

Below is the impedance wit h the capacitor increased to 2 uF (blue tr ace). The ori ginal (uncompensated) impedance is s hown in green. The 2 uF capa citor has flattened out th e impedance so that it rises onl y slightly above 8 Ohms. Since it is eas y to do let's continue to in crease the capacitor value and see if we can get a furthe r impro[...]

The screen below shows the effect of inc reasing the capacitor to 3 uF (blue trace). The inc rease from 2 to 3 uF gave even further i mprovement as the impedance above resonan ce is now quite flat. J ust to see what happens, let's increase the cap acitor further to 5 uF.[...]

Below we see the effect of incre asing the capacitor to 5 uF in t he lowest (blue) trace. It seems we have gone too far with the incr ease to 5 uF. The impedance in the 2 to 3 kHz range has been redu ced to the DC resistance value and is now rising above the previous m easurement with the 3 uF capacitor. This rise may be due to an interaction with [...]