Sparta AS-30B Technical Manual Download

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Summary of Contents for AS-30B

Page 1: ...SPARTA AS 3OB AUDIO CONSOLE TECHNICAL MANUAL...

Page 2: ...nominal into 10K ohms FREQ RESPONSE All outputs less than 2db down 20 Hz to 20 kHz NOISE DISTORTION CROSSTALK Below 65 db at 0 vu out with 55 db low level input Below 75 db at 0 vu out with 10 dbm hi...

Page 3: ...have any general comments as to how we might be of greater service your suggestions will be greatly appreciated AS 3OB Customer SERIAL NO 2 f DATE r PWR SUP SERIAL NO p CAL BY No 0F PREAMPS OUTPUT DI...

Page 4: ...ended for single ended high impedance loads the minus input terminals of the consoles are connected to the shield and the console now appears as a single ended high impedance 10K load The Audition and...

Page 5: ...r 8739 solid Either may be used although it is generally more satisfactory to use solid wire in a permanent installation where flexibility is not required since solid wire is easier to handle and less...

Page 6: ...pending of course on the sound level and microphone used In a normal situation then the preamplifier output is at essentially the same level as the high level input signals resulting in approximately...

Page 7: ...put cables Mixing takes place by feeding the output of each mixer potentiometer through a high value series resistor 10K or 27K to a common mixing bus which in turn leads to a mixing amplifier The mix...

Page 8: ...ubstantially the same level as originally fed to the mixer pots with the mixer pots at their usual operating positions about one o clock Since a current mixer operates from a relatively high source im...

Page 9: ...er must be isolated from the line with a pad typically 4 db to prevent interaction with line reactances Finally the line amplifier output impedance must properly match the line transformer primary so...

Page 10: ...e line transformer output ahead of the line pad which allows an added 4 db of attenuation in the meter pad for increased isolation A balanced H pad is not required since the meter need not be balanced...

Page 11: ...GENERAL stage of the program line amplifier Since there are no active or non linear components to follow the monitor provides constant assurance of both level and quality whereas the VU meter alone o...

Page 12: ...t overload characteristics With normal microphone input levels the output level to the mixer will be approx 0 dbm The maximum output level of the 1018 before clipping is in excess of 14 dbm which assu...

Page 13: ...n p h a s e w i t h t h e s i g n a l i n p u t t o t h e b a s e o f Q l This consitutes negative feed back since the feed back attempts to cancel the input signal The open loop gain without feed bac...

Page 14: ...f Q3 is set by the collector voltage of Q2 and since the collector current of Q2 is also the emitter current of Q2 any change in the collect or voltage of Q2 also appears as an inverted change at the...

Page 15: ...or towards ground If the operating point is beyond the limit given but still capable of moving further in either direction the amplifier will still be operative it simply will not have as much dynami...

Page 16: ...ugh high value resistors of 10K ohms or more Each input current then follows the path of least resistance into the mixer amplifier independent of the condition of the other mixing channels thereby pro...

Page 17: ...3 then forms a negative feedback path which assures that Ql s operating point remains within a reasonable range Normal operation of Ql will be obtained at any collector voltage between approximately 5...

Page 18: ...tor R7 which is ten times larger than R8 so it must cause ten times the voltage change The voltage gain of Q2 then must simply be the ratio of R7 to R8 or ten In normal application Q2 is loaded by the...

Page 19: ...Q2 can only rise to the point where the combined feedback currents from R3 and R6 approach cancellation of the input current with hthe current through R6 being dominant Very low distortion results ty...

Page 20: ...to the input signal at the base of Q3 thereby setting the ac gain When power is first applied C13 must be charged to one half of the supply voltage through Q6 and to protect Q6 the charging rate must...

Page 21: ...e to the rising reactance of C13 This change will appear as an error signal when compared with the input and allows the reserve open loop gain of the amplifier to correct the error thereby permitting...

Page 22: ...for the 60 ohm primary of the line output transformer The transformer produces 10 db of voltage gain which is followed by a 3 db loss in a resistive isolation pad The rms signal voltage at the emitter...

Page 23: ...spect since subsequent gain is the highest Hum 120 Hz would of course lead one to the power supply Distortion will be practically non existent if normal dc and ac gain is obtained The line amplifier f...

Page 24: ...ended warranty of 50 of the replacement cost being allowed should failure occur during the second year Electron tubes and silicon rectifiers bear only the warranty of the manufacturer thereof in effec...

Page 25: ...z o u UJ D_ to Cu UJ vt Cu U I Z o x CL Q cxr O O U CO o o o o u 03 N O CO j z o i u 2 3 CO o o H O 3 O n ru u o c_ a z z H 2 Z o O z D o CN r cs O co CO r N C V to o K d a z o z o COOOM IN V u 0 CLC...

Page 26: ...z o o 0 N CO 3 AAAtVW1 1 A o o UJ uu U Q O c e o Z K a us O O H O es H O o o j o D e o wl c o 1 0 4jt o VI 0 J o 4 o 3 u c E o o c w 0 O 6 o to vn rO I r Or M a o oo fx CN cc U UJ o o u 1 o hx fx o io...

Page 27: ...D a c...

Page 28: ...7 0 co Z 0 Ui i V r V v tO Z UI u 4 0 1 M QQ CL M QQ V v o CO CL CL CL r 00 ULI o CL K O K V VI O T O l W i 0 2 o E S w N r o u 6 a oc a o u K f v U f C r r t C 5 t i fj 1 X G 0 c r T t o 0 o C 52 C 1...

Page 29: ...V JQ E U CN CN V if E D X c o U o ft 4 E a Cd O u u z O or h U LU X to o tx KJ 3 CL b D O n o CM CN o __ O 00 Z u 5 3 5 r O O Ui z o z o o Ics Cr D CL z n z o...

Page 30: ...g o o i o s o c CD Si CO CM 2 H O cd hHI hHI cu 0 CO O CO j i m CO S W s S O M I I H 3 S 2 K c w H 6 o o CM CD 1 3 o H W O CO O tD o 2 i I o Q 2 CQ Nd O r H w E i I Q w HH a w S i l o O o od CM M CO...

Page 31: ......

Page 32: ...21e w 3 1 MONITOR 1 U e Tf 1rcfc ot C 3S i r i 4 EUCTfto ic crm Q iflnow SACRAMENTO CALIFORNIA yS828 AS 30B AUDIO CONSOLE rw 5 C j V V7 SOU S IOS c SOU S IOS c...

Page 33: ...FI does occur in even the best of installations oecause of its virtually unpredictable nature It does not necessarily require a strong field for RFI to result and it is not uncommon for an audio syste...

Page 34: ...simply because there is no way to force a component such as a semiconductor to recognize the difference between a change of voltage or current at audio frequencies and a similar or greater change at...

Page 35: ...the silence of a blocked amplifier stage If the offender is a VHF FM carrier however it will most often be entering the audio system via a conductor or cable that is resonant or tuned at or near the f...

Page 36: ...and that any wire or metal structure will be resonant at many different frequencies The most prevalent example of course is the twisted pair shielded audio cable feeding a console which may act as a...

Page 37: ...re is no hard and fast rule however and it is wise to try various combinations When the interference is in the VHF range it will often be found that shortening or_ lengthening a cable will eliminate R...

Page 38: ...relationship if the audio line impedance is higher the capacitor should be proportionally smaller and visa versa In severe circumstances RF chokes may be inserted in selies with the audio lines and wi...

Page 39: ...on resulting from point contact of two dissimilar metals The significant factor is that a junction of any two dissimilar metals or metal compounds is potential detector Now we cannot prevent such junc...

Page 40: ...nent along with normal program A sufficiently high level of RF however could completely block a transistor causing complete loss of any audible symptom so it becomes quite necessary to allow for varyi...

Page 41: ...o equipment designs include equivalent suppression at the most likely points of RF1 detection We can conclude that RF1 is always a possibility in an audio system and can appear unexpectedly when a cha...

Page 42: ...ary and your Colordots made of heavy acetate will last for years Since Colordots are transparent a code or reference can be incorporated underneath which will be clearly seen for the life of the conso...

Page 43: ...159 258 397 3 159 278 421 4 178 278 421 5 178 298 437 6 219 338 457 7 238 338 457 CRIMPED LEAD VERSION ONLY MARKING CODE TABLE 4 CAPACITANCE MFDS WORKING VOLTAGE COLOR CAP 1ST SIGNIFICANT NUMBER RING...

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