Servo Sub Manual - The Spica Speaker Enthusiast
Contents
1. SPICA SERVO SUBWOOFER OWNERS MANUAL RRR EEE EERE EER EEE EE REE ERR ER ERE EEE The Installation procedures given in this manual MUST be followed for the SERVO to perform properly FRR RR RIE EERE ERE E EE CONTENTS PAGE Introduction 2 Checking system polarity 2 Changing the SERVO s polarity 3 Passive interface setup 4 Making the connection amp Placement 7 Setting levels 9 Some fine points 10 Technical specifications 12 Warranty 12 1401 PASEO DE PERALTA SANTA FE NEW MEXICO 87581 aaa aaam INTRODUCTION Your new SPICA SERVO subwoofer is designed to extend the low frequency performance of the SPICA TC 50 speaker system Its computer optimized crossover network servo error correction circuit specially designed 8 woofer and internal 72 watt power amplifier all contribute to give a dramatic improvement in your system s clarity and definition while allowing higher sound pressure levels to be obtained And it does all of this without degrading the superior stereo imaging that the TC 58 is famous for We are confident that you will be more than pleased with this addition to your system An important consideration in the design of the SERVO was to make it flexible enough to be used with whatever receiver or power amplifier you might be using for your TC 5 s while retaining the sonic purity that your system already has To accomplish this a simple passive filter is used in the portion of the crossover network that feeds the TC2. 18 SOME FINE POINTS Before going on further with this take some time now and listen to some music through your new system Listen to a variety of material and notice how different the character of the low freguency part of the music is as you go from one recording to another Then come back and we ll go through some fine points regarding the setup If you re pleased as punch with your system and can t imagine that it could be any better then you re all done and you need not concern yourself with this section on fine tuning your system If you d like to extract the last ounce of accuracy out of it and you don t mind a little tech talk then read on There are two factors that can affect the absolute accuracy of the setup procedure you ve just completed The first factor is a combination of a the distances from the SERVO and your listening position to the various surfaces in your room and b the liveness or deadness of the floor immediately in front of the SERVO which can be tuned by fine changes in the placement of the SERVO The second factor is variations in the sensitivities of the drivers in both the TC 5 and the SERVO which can be tuned by adjustments to the SERVO level control This is what we call OPTIMIZING a procedure that is a very meaningful one for us here at SPICA It is distinguished from IDEALIZING in that it takes into consideration the immutable undesirable conditions as well
3. 3dB 88 Hz Electronic with computer derived slope 110k Ohms open 20k Ohms one input shorted Inverting for use with non inverting TC 50s Continuously variable within a 12dB range Solid state 7 watts RMS minimum 17 5 44 5 W X 14 5 36 8 H X 15 875 40 3 D 48 18 25 System type Woofer Enclosure Volume System Resonance Q Low Frequency Extension Woofer Hipass Crossover Lopass Crossover Input Impedance Polarity Level Control Power Amplifier Size in inches cm Weight in lbs kg WARRANTY To the original purchaser SPICA warranties the SERVO to be free from mechanical defects for five S years and electronic defects for one 1 year from the date of purchase when purchased from an authorized SPICA dealer Your sales receipt is your proof of purchase This warranty excludes damage caused by user abuse carelessness and modifications other than those covered in the owners manual SPICA reserves the right to make final determination of warranty coverage SPICA makes no other warranties either expressed or implied 12
4. and four values of smaller ones silver color The large parts have values of 18 839 and O56 If the value you need is within 81 of one of these just grab a pair of them and proceed on to the Capacitor Installation section Every one else gets a little lesson on the inconsistent ways in which the values of the smaller parts are marked on them Some manufacturers mark these parts in microfarads and others in picofarads 1 microfarads is 10008 picofarads Likewise 5 microfarads is S 0 picofarads So while we are discussing values in microfarads be aware of this difference in the way these parts may be marked To convert picos to micros place a couple of zeroes in front of the picofarad value and then place a decimal point six digits to the left starting at the right end of the number and there you have it INPUT IMPEDANCE kOhms PASSIVE INTERFACE CAPACITOR CHART DK f t EEA EE BGK feeee reer n nebo ee een ee ES S Pania So ree 6Bk Pees eee eee oa a Cen Cee Coen ee ee ee R EA EEEE NEE E E VEEE E tacscceueccsnesceeseused 26k Laer 6090 683 76 G68 661 854 84 40 B32 625 Gi8 CAPACITOR VALUE Microfarads Okay A calculator will come in handy now From the three larger parts select the value that is less than the value you need Subtract it from the total Then find the nearest value that is less than or equal to this remainder Do this until you ar
5. 50s This part of the setup procedure represents a minor inconvenience for you the end user Although the procedure is a somewhat technical one we have made every effort to present it as simply as possible Please read and follow the instructions carefully Some of the tools you will need are gt CASSETTE PLAYER for setting levels gt MEASURING TAPE for physical placement gt SOLDERING IRON for capacitor installation For setting the relative level of the subwoofer with greater accuracy a method is provided that requires the use of an AC VOLTMETER If you do not hava a soldering iron your SPICA dealer will be able to assist you in installing the capacitors into the passive box We mentioned above that the SERVO does not degrade the stereo imaging abilities of the TC 58 Another way of saying this is that the SERVO is a phase coherent addition to the TC 50 This is quite a distinction from all of the generic subwoofers available which by their very nature can only give generic results If by chance you are using the SERVO with satellite speakers other than the TC 50 we have no way of predicting how sucessfully the SERVO will match up with them and the setup procedures given in this manual may not be applicable to your system We would like to acknowledge the fine folks at PS AUDIO for the design of the internal 70 watt power amplifier and the servo circuit CHECKING SYSTEM POLARITY Suppose you were stan
6. position be qreater than the distance from the TC 5 s to your listening position by a certain amount If this is not done all of the other system parameters will be thrown out of whack Also where you place the SERVO s depends on whether you are using one or two of them in your system Fortunately this is a very simple procedure Al you need is a MEASURING TAPE and possibly a helper FOR SINGLE SERVO SYSTEMS As shown in FIGURE 4 the SERVO should be placed in between the TC 5 s Placing it anywhere else in your room will result in reduced accuracy because the SERVO must be placed at a fixed distance offset from each TC 5 And since one SERVO is serving this function for two TC 5 s placing it in between the TC 50s is the only way this condition can be satisfied SINGLE SERVO PLACEMENT FOR DUAL SERVO SYSTEMS As shown in FIGURE 5 the SERVOs should be placed as closely as possible to each TC 5 Having them on the outside is slightly preferable but the inside is fine For optimum performance you may want to consider using the stands which have been specifically designed for the TC 5 when used with dual SERVOs They are made by Chicago Speaker Stand These stands mount on top of the SERVO enclosure placing the TC 5 at the correct distance offset and can accomodate a range of listening heights through their tilt adjustment Ask your dealer for more information SSA Sg e DUAL SERVO PLACEMENT FIGURE 5 ALL SYS
7. Now give each a value of and each a value of 1 Add up all the values from the SOURCE device to the PREAMPLIFIER MAIN OUT If the number you get is an EVEN number or ZERO no change in the SERVO is required If it adds up to an ODD number you must follow the procedure given below to change the polarity of the SERVOs woofer Now check the polarity of the amplifier being used with the TC 50 Add its value or 1 to the previous total If this new total is EVEN or ZERO the terminal of the amplifier powering the TC 5 s should be connected to the red input of the TC S s as is normal If it is ODD you should reverse the connections to each TC 50 at its input terminals CHANGING THE SERVOs POLARITY WARNING 1 UNDER NO CONDITIONS SHOULD THE SERVOs POWER CORD BE PLUGGED INTO AN AC OUTLET WHILE THIS OPERATION 1S BEING PERFORMED The damage that results is not covered under warranty and personal injury is possible If you have determined above that the SERVO s polarity needs to be reversed you will need a SOLDERING IRON and a PHILLIPS SCREWDRIVER to change it Place the SERVO on a tabte or bench and proceed as follows 1 gt MAKE SURE the SERVO s power cord is DISCONNECTED 2 gt Remove the grill frame from the front of the enclosure by tugging firmly on it at the bottom of the enclosure 3 gt Using a PHILLIPS SCREWDRIVER remove all eight of the screws that secure the woofer onto the enclosure 4 gt Free the woofer and s
8. TEMS 1 gt Put a small piece of masking tape on the couch or chair you listen in at a point near where your head is located when you are seated 2 gt Use your measuring tape to find the distance from this point to the BOTTOM FRONT EDGE of one of the TC 5 s and write it down 3 gt Now measure the distance to the other TC 50 from the same point and move it backward or forward until the two distances are identical 4 gt Place the SERVO s in the location described above at a distance that is 4 5 inches GREATER than the TC 52s as measured from the same point to the BOTTOM FRONT EDGE of the SERVD s 5 gt Plug the patch cords from the PASSIVE INTERFACE inta the SERVO s If you are using one SERVO it makes no difference which cord is plugged into which jack If you are using two check to make sure your lefts and rights are consistent with the rest of the system but don t use the furnished shorting plug until we find out later whether you need to or not amp gt Plug the power cord of the SERVO s into an AC outlet DON T turn it on just yet SETTING LEVELS It is not uncommon these days for people even non hobbyist types to have an AC Voltmeter around the house or at least to have a friend that does If you do here s an opportunity to put it to good use On the back panel of the SERVO is a level control It is used to set the loudness of the SERVO to the proper level There is sufficient gain 12 dB in this control to
9. as the desirable ones in any circumstance The very walls in your room are one such undesirable condition in that they restrict the free expansion of the sound pressure wave and create resonances and cancellations at frequencies that are related to the distances between these surfaces This is actually a very complex subject but the long and short of it is that your listening position may be placed in a location where there is a strong buildup or cancellation of acoustical energy and this may be happening right in the frequency range where the SERVO and the TC 5 s are trying to combine their contributions to the overal sound If the distance from the SERVO to the wall behind it is identical to the distance from your listening position to the wall behind it you are most likely listening in one such problem area The solution is to make these distances unequal by relocating your listening position or the TC S s and the SERVO together After making any changes to the position remember to go through the procedures on placement again to ensure that the relative distances are correct Now lets take a look at the effects of the reflective character of the floor in your room The SERVO is specifically intended to be placed on the floor or floor coupled as we call it At low frequencies this placement effectively eliminates the floor from being one of the early reflective sources that we mentioned above At higher frequencies this becomes
10. ding in front of a mirror that turned everything reflected in it upside down All the features of the image would be there but they would be inverted This is a visual analogy of what is called POLARITY The audio industry has not established any polarity standards so some pieces of equipment invert the signal as it passes through them and others do not In order to determine the polarity of your system you must find out which pieces in your system invert the signal and which ones do not This information is often given in the owner s manual of each piece If it is not contact your dealer or the manufacturer to find this out now g FIGURE 1 SYSTEM POLARITY Power Amplifier Head Pre a Amplifier Amplifier Phono Cartridge To assist in the polarity hunt a sketch of your system in the form of a block diagram will help immensely FIGURE 1 shows such a diagram of a typical system Draw up a Similar diagram for your system including everything from the source device phono cartridge tape player etc to the speaker outputs of your receiver or power amplifier If you have a receiver the MAIN OUT jacks on the back panel are functionally the same as the Pre Amplifier in FIGURE 1 The or above each block refers to the inverting or noninverting status of each piece where signifies the inverting condition Do the same on your diagram noting the polarity of each piece above it
11. e within 82 of the value you need The nearer the better but this accuracy is sufficient If your amp s input impedance is 460K Ohas or greater get within 1 of the target value CAPACITOR INSTALLATION Its time to fire up your soldering iron You will find a length of solder in the PASSIVE INTERFACE box it s good stuff so use it If you needed more than one capacitor to get your target value hold the smaller parts length wise along the larger part and GENTLY wrap the lead of each smaller part a couple of turns around that of the larger at each end The leads of the small silver parts are a little fragile so don t tug on them too hard You will do this twice once for each channel Do yourself a favor and double check your work before you solder You should have two capacitor clusters with identical parts in each Solder the capacitors together working as swiftly as possible so as not to damage the parts Cut the leads of the smaller parts off leaving the leads of the larger part extending on either end Before installing the parts into the PASSIVE INTERFACE box take a look at FIGURE 3 which shows the correct orientation of the parts and their connection inside the box The installation procedure will be described for one capacitor and should be repeated for the other as well CAPACITOR INSTALLATION FIGURE 3 Place the box so that the insides are exposed Cut the leads of the capaci tor so that the total length fr
12. et it face down in front of its mounting hole 5 gt Make note of which color wire is connected to which terminal on the woofer From the factory the GREEN wire is connected to the woofer terminal marked with a RED DOT near it gt Unsolder both wires and resolder each of them to the terminal that was previously connected to the other color 7 gt Replace the woofer into its mounting hole lining up the screw holes in its frame with the holes in the enclosure 3 8 gt Screw each screw in part way making sure the woofer is seated evenly all around then tighten thea up in a cross wise fashion DO NOT overtighten them or the holes will strip They should be firmly snug 9 gt Replace the grill frame onto the enclosure pushing around the perimeter to engage the Velcro fasteners 10 gt VOILA PASSIVE INTERFACE SETUP To interface properly with the SERVO the signal sent to the amplifier that is driving the TC S s must be high pass filtered at the correct frequency This is accomplished by installing the proper value of capacitor into the PASSIVE INTERFACE box The value of this capacitor is determined by the input impedance of the power amp you are using If you are using a receiver to power the TC 5 s it must have Preamp Out Main Amp In jacks on the rear panel If yours does not you should contact your dealer to make the appropriate modifica tions to your unit Find out the input impedance of your amplifier unit This info
13. f blowing up the power amplifier in the SERVO Before measuring the voltages at these Test Points gt YOUR VOLTMETER MUST BE SET TO MEASURE AC VOLTS If it is set on the Resis tance mode it will insert a reference voltage into the SERVO circuit and most assuredly will cause some damage YOUR VOLTMETER MUST NOT BE CONNECTED TO AN AC OUTLET but should be operating on its internal batteries If EITHER test point is connected to an AC GROUND the SERVO will go up in smoke before your very eyes v If you have a SINGLE SERVO system turn your balance control all the way to one side or the other and start at step 4 5 gt Set the balance control on your preamp receiver to its center position amp gt Turn the SERVO s power switch on 7 gt Start the cassette running and set the level to a comfortable one using your preamp receiver s level control Do not change the setting of this control during the setup procedure 8 gt Measure the voltage at the input terminals of the TC 58 and write it down 9 gt MULTIPLY this figure times 7 18 gt Hook the voltmeter to the Test Points on the SERVO 11 gt Adjust the SERVO level control until the voltage measures the same as the figure obtained in Step 9 12 gt For DUAL SERVO systems repeat Steps 8 through 11 for the other channel 13 gt Replace the grill frame onto the enclosure pushing around the perimeter of it to engage the Velcro 14 gt Th th that s all folks
14. he cassette running and set the level to a comfortable one using your preamp receiver s level control Do not change the setting of this control during the setup procedure Disable the SERVO by turning its power switch to OFF 7 gt From your listening location listen to the loudness of the tone that comes through the TC 5 s alone 8 gt Disable the TC 5 s and turn the SERVO power switch to ON 9 gt Listen to the loudness of the tone from the SERVO alone and adjust the SERVO level control until it is the same as it was from the TC 5 s If there is any doubt set the SERVO level on the low side 1 gt Repeat steps 6 through 9 until you are satisfied that the levels from the TC 5 s and the SERVO are the same 11 gt For dual SERVO setups turn your balance control to the opposite side and start at step b again 12 gt Skip to the section on Some Fine Points EMPIRICAL METHOD This is the easiest and most accurate method Making sure not to move the SERVO from its optimum location remove the grill frame from the SERVO Abave the woofer to the left flush with the face of the enclosure are two exposed Test Points Before we proceed a word of caution is in order These Test Points are connected DIRECTLY to the power amplifier and are also part of the SERVO s comparator If they are accidentally shorted together connected to an AC ground or if any voltages are applied to these test points you stand a good chance o
15. increasingly less true so that the absorbtive character of the floor immediately in front of the SERVO effects the smoothness of the SERVO s output at higher frequencies which in turn has a subtle or not so subtle depending on your attentiveness effect on the audible result We recommend that a rug be placed under or immediately in front of the SERVO Mark the current position of the front of the SERVO on your floor with a small piece of masking tape From your collection choose some recorded material that has either very coherent depth in it or very percussive low frequency information Choose a 38 second long passage that grabs you and listen to it with the systea set up the way it is now Listen in particular to the quality of the impact of low frequency transients to the focus of the instruments that seem to come from further back in the soundstage and to the general sense of warmth of the overall sound Now experiment with moving the SERVO back a little bit from the original position listening to the same passage after every move 11 There will be a place where the three above qualities will come together dramatically If you have gone more than an inch or so away from the original position you have gone top far and you might want to choose a different selection of program material To correct for the variations in the sensitivities of the various drivers in the system you can make minute adjustments to the SERVO
16. l be listening to the tone recorded on the SERVO SETUP tape first played through the TC 5 s alone then through the SERVO s alone You therefore need some way of disabling the output to the TC 5 s when listening to the tone through the SERVO To accomplish this gt If you have a separate power amplifier for the TC 5 s all you have to do is turn that unit off gt If you have a receiver or integrated amplifier that has speaker switching all you have to do is switch the speaker selector to off or to the other output gt If you have none of these you must turn the receiver off without changing the level control on it disconnect the patch cords from the Passive Interface Box to the receiver main input then turn the unit back on Whichever is appropriate for your case it is referred to in the instruc tions that follow as disabling the TC 5 s If you are using a DUAL SERVO setup the instructions given should be repeated for each side Use your balance control to get the tone output from the side that the setup is being done for During the setup if you should find that 9 the SERVO level control is turned all the way down and is still too loud then insert a shorting plug into the unused input and start the level procedure again This will give an additional 4 dB of attenuation If you are using a SINGLE SERVO setup place your balance control in the center position Do not change it during the setup procedure 5 gt Start t
17. level control using the same criteria as given above Be sure to mark your original position before you start so that you can return to it for comparisons Some words of caution are in order here If you do make adjustments to the SERVO level control keep the following in mind gt We Americans as a culture tend to be bass freaks with our sound systems so there is going to be a tendency to want to keep cranking it up in order to achieve that indistinct sameness in bass quality that we have all grown up with You will find that continually increasing the SERVOs loudness above the proper level actually lessens the perceived bass Things start to cancel each other rather than working together DO NOT use the SERVO level control as a bass tone control Use your preamps bass control to compensate for bass deficient recordings The SERVO has a built in rumble filter We have purposely set it at the extremely low frequency of 4 Hertz If you are a playing a record that is badly warped b playing your system VERY loud c boosting the bass with your bass tone control then you should consider engaging the rumble filter on your preamp receiver if it has one Otherwise you should leave it off Avoid the use of the LOUDNESS button on your receiver Ne v w v TECHNICAL SPECIFICATIONS Sealed box 1 25 cu ft 31 Hz Total 5 3dB 25 Hz 8 diameter with 1 peak to peak excursion Passive lst Order
18. match the sensitivity of almost any amplifier you may be using to drive the TC 50s There is also enough gain here so that if the control has inadvertantly been cranked up some damage could be done to the amplifier or woofer in the SERVO Turn the control to its fully counter clockwise position We are providing two methods of setting levels one is strictly subjective the other is empirical If you have access to a voltmeter we strongly suggest you use the empirical method why guess if you don t have to Both methods require the use of a CASSETTE PLAYER the quality of the unit is not important The level setting procedure takes advantage of the following fact AT ONE FREQUENCY THE ACOUSTIC OUTPUT OF THE SERVO AND THE TC 50 ARE THE SAME We have furnished a cassette that has five minutes of this frequency recorded on each side of it If you are going to follow the SUBJECTIVE METHOD a friendly assistant would be helpful BOTH METHODS 1 gt Connect a cassette player to the appropriate inputs of your system 2 gt Turn the level control on your preamp or receiver all the way down 3 gt Set your Bass and Treble controls to their center off positions They should remain off for the entire setup procedure 4 gt Turn all of the components in your system ON except the SERVO s 5 gt Place the SERVO SETUP cassette into your player SUBJECTIVE METHOD This method requires a little bit of explanation before we jump right into it You wil
19. om end to end is just shy of the long dimension of the box Bend one end of the leads to form a small hook Hook the lead through the small hole in the CENTER POST of one of the phono jacks at the long end of the box and the other end through the center post of the phono jack directly opposite it Do not cross the leads of the two parts if they touch each other you will convert your wonderful stereo into a monaural system although it is not likely to do any damage Crimp the leads loosely onto the posts and solder them Now put the top onto the box securing it with the screws provided and you re done MAKING THE CONNECTION Place the completed PASSIVE INTERFACE behind your other components Turn all of the components in your system OFF With patchcords connect the output of your preamplifier to the jacks marked IN on the PASSIVE INTERFACE making sure aS always to keep your lefts and rights consistent if you don t know your left from your right your SPICA dealer is qualified to help you Connect the jacks marked SATELLITE OUT to the input of the power amplifier that is driving the TC 58s Connect a long set of patchcords to the jacks marked SERVO OUT and let them be for the moment PLACEMENT In phase coherent systems as in life in general TIMING IS OF THE ESSENCE In order that the timing relationships of the SERVO and the TC 50s be correct it is necessary that the distance from the SERVO to your listening
20. rmation is Normally given in the owner s manual if it is not your dealer can find it out for you Locate the impedance value on the vertical axis of the chart in FIGURE 2 on the next page Using a straight edge placed parallel to the bottom of the chart at the point located mark the point where it crosses the curved plotted line Now drop this point straight down to the bottom of the chart and mark it Find the value of the nearest major division the ones that are labelled and count the number of small tick marks between this major division and your mark If your mark is to the left of this division ADD 01 to the number at the major division for each tick mark you counted if is to the right SUBTRACT 1 for each tick mark The total you get is the capacitance in microfarads you will need to install into the PASSIVE INTERFACE box If your unit has an input impedance outside the range of the chart you will have to calculate the value or ask your dealer to do it for you The formula iss 1888 92 Input Impedance Capacitor value in microfarads aa LKX XBR l Ny Pio He CAPACITOR SELECTION Some of the values necessary are not standard values so they must be obtained by combinations of parts We have provided a selection of capacitors with the PASSIVE INTERFACE that will satisfy the required values Open up the PASSIVE INTERFACE box and take a look at the parts in it There are three sets of larger value capacitors yellow color
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