background image

 

 

 
 
 
 

 

 

28 

 

11. TROUBLESHOOTING 

 
 

11.1. Faults caused by external issues 

 

Buzzing and hum in the speakers 
 

 

Possible cause: multiple grounds 

 

Hum in an audio system is often caused by several system components having their own separate 
grounds. It is particularly common in systems containing tuners, VCRs or satellite receivers, as 
these components are connected to an aerial.  Because aerials and cables are always grounded, 
ground loops can form between the aerial connection and other grounded equipment. Other 
equipment that is normally grounded may include PCs with sound cards, and some CD/DVD 
players and DACs. 
Although the V 70 SE is grounded, its signal ground is a "floating" ground, which means that the V 
70 SE cannot itself create ground loops. Hum can only be caused when it is connected to other 
items of equipment. 
 

To fix the problem 

Before trying to fix the problem, find out which of your system components is responsible for 
generating the hum. 
Procedure:   

Unplug all source equipment, including any equalizer if used, from the V 70 SE, leaving only 
the loudspeakers connected.  

Reconnect the components back to the V 70 SE one at a time. As soon as the hum reappears, 
you have two grounded components connected to the V 70 SE. You must now unplug your 
components in reverse order to find out which of them is grounded. 

Usually, the hum will still appear even when the problem components are switched off. The ground 
causing the problem is always connected, since it is not broken when the power switch is operated. 
 
Now that you know which components are grounded, you can discuss the problem with your 
dealer. 
One option might be to use a signal-isolating filter on the aerials or cable networks. These devices 
do not normally have any adverse affect on the sound or picture quality of tuners or TVs. Other 
possible solutions could include using an isolating transformer or an isolating device offering 
complete galvanic isolation. Please seek the advice of a specialist. 
Power strips with built-in filters, mains filters or replacement mains cables are not appropriate 
solutions. 
  

Note 

Switching power supplies are quite common nowadays. These are often fitted with a protective 
earth terminal (PE) and an RFI filter. When using such units, the protective earth terminal 

must

 be 

connected to the wall socket. 

You must never remove this protective terminal, as doing so 

could cause high levels of radio frequency interference to enter your system, which could 
affect the operation of other digital equipment, including remote controls.

 

 

Summary of Contents for v70se

Page 1: ...V 70 SE ...

Page 2: ...insights into the interaction of amplifier and loudspeaker With tube amplifiers in particular a general reluctance to depart from the classic circuit designs has not done the technology any favors Although today s loudspeakers and source equipment provide better performance than ever before they also present greater demands on amplifiers Modern sound reproduction equipment delivers a level of perf...

Page 3: ...nection options 18 6 1 Protection 18 6 2 Soft Start 18 6 3 Ecomode 19 6 4 Front Channel 20 6 5 Pre Out regulated 20 6 5 1 Using with an active subwoofer 20 6 5 2 Using in bi amped systems 20 7 Tubes 21 7 1 Removing the grille see 3 2 21 7 2 Tube layout 21 7 3 BIAS measurement facility 22 7 4 Replacing the tubes 24 7 5 Running in the tubes 24 7 6 Tube service life 24 8 The programmable remote contr...

Page 4: ...dstage size and articulation This enables optimizing the V 70 SE in respect to the speaker which is a tremendous benefit if the speaker is difficult to drive Input Section The input section of the V 70 SE features five line level single ended Inputs with an optional internal Phono board one balanced Input and two single ended Outputs One is a standard record output the other Pre Out is a regulated...

Page 5: ... engineer to replace blown fuses with ones of the same type and rating If your amplifier requires servicing please ship or take your equipment directly to OCTAVE or to one of our authorized service centers Modifications to OCTAVE equipment Use audio grade fuses and other power cables at your own risk The use of such devices will void the warranty This also applies to the use contact fluids on the ...

Page 6: ...ble materials gases or vapors Avoid areas where there may be heavy accumulations of dust or where the unit may be subject to mechanical vibration Place your OCTAVE amplifier on a stable level surface 2 Grille Never operate the amplifier without the protective grille in place 3 Ventilation Make sure that your amplifier has an adequate flow of air around it If you intend to install your equipment in...

Page 7: ...packed separately Power cord Remote control with owner s manual 2 screwdrivers 1 x 2 mm flat bladed screwdriver for adjusting the BIAS 1 x 2 5 mm Allen key for removing the cover Owner s manual with warranty card 3 2 Removing the grille 1 For your own safety make sure that the amplifier is not connected to power outlet 2 Completely remove the 4 hexagonal screws using the Allan key supplied There a...

Page 8: ...ll as tube life considerably by protecting against stress caused by typical high inrush currents during switch on 1 Check that the Ecomode switch on the rear panel is in the Eco off position 2 Connect the V 70 SE to the mains On new units this switch is set to off at the factory Ecomode Eco off Eco on Amp off 3 Switch on the V 70 SE using the amplifier s mains power on off switch Some LEDs will il...

Page 9: ...e tubes are still cold you would adjust the wrong BIAS After an additional 5 to 10 minutes the BIAS control LEDs will change from yellow to green This indicates the correct bias and the unit is ready If you notice any irregularity in the display please refer to chapter 7 3 3 6 Connecting other components to the V 70 SE 1 Be sure to switch off the V 70 SE again 2 Connect the other components in you...

Page 10: ...nnect the amp from mains before connecting the Black Box Integrated amplifier V 70 SE Serial No Made in Germany Ecomode Eco off Eco on Amp off L R CD 2 Pre Out Front Ch Tape Rec Aux 1 Aux 2 Phono CD 1 Additional line level analogue component e g video Turntable CD player with balanced output Speakers right left to wall socket Active subwoofer Multichannel source such as DVD Additional line level a...

Page 11: ...evel input for tuner etc Pos 3 Aux 1 RCA line level input for video etc Pos 4 Aux 2 RCA line level input for video etc Pos 5 CD 2 XLR line level input for CD SACD or similar Pos 6 The electronic BIAS measurement system is activated see chap 7 3 Pos 7 Front Ch Multichannel input In this mode the V 70 SE functions as a two channel power amplifier The volume control is bypassed See chap 6 4 The recor...

Page 12: ...ched on Protection Red LED lights up when the electronic protection system has switched off the amplifier in response to an amplifier fault see chapter 6 1 Soft start Lights up during the soft start process immediately after switch on This LED extinguishes after about 1 minute when soft start has been completed see chapter 6 2 Front Ch Illuminates when multichannel bypass function is selected see ...

Page 13: ...e level input for Video etc or MM MC input with Phono option AUX 1 RCA line level input for Video etc Tape rec Record output for tape or DAT GND Ground connector for Turntable Front Channel Input for the front channel of a multichannel receiver DVD player see chapter 6 4 Pre Out Regulated preamp output for active subwoofer etc see chapter 6 5 CD 2 CD line level input XLR Pin configuration for XLR ...

Page 14: ...mplifier section see chapter 10 You should switch off the V 70 SE using the power switch before connecting and disconnecting the Black Box AC supply socket IEC socket with integrated fuse holder The fuse is located in a pullout compartment underneath the socket You can open the fuse compartment after removing the plug Fuse For 230 240V 3 15A slow blow H 5 x 20 mm For 115 240V 5A slow blow H 5 x 20...

Page 15: ...he output tubes A fault in one of the preamp tubes which overloads the affected channel Once the protection system has cut in the only way you can turn the V 70 SE back on is to turn the on off switch off and then on again Allow the unit two minutes to cool down before switching it back on If possible identify and eliminate the cause of the problem see chapter 11 Troubleshooting If it is not clear...

Page 16: ...co off The Ecomode electronic is off the amplifier is on Eco on The Ecomode electronic is activated Ecomode is signal actuated after a 9 minute silence Ecomode switches in automatically The soft start LED 6 indicates that the Ecomode was turning down the unit As soon as the Ecomode circuit detects the presence of an input signal from the CD player for example it will automatically power the V 70 S...

Page 17: ...bi amped systems Another option provided by the adjustable Pre Out is Bi amping via the V 70 SE s internal preamplifier The V 70 SE would ideally handle the mid high portion of a bi amping setup using a second power amplifier fitted with its own volume control to take care of the bass In this configuration switch on switch off noises from the Pre Out may prove to be a problem The best way to deal ...

Page 18: ...This is facilitated by the option of setting the BIAS current to two different values low and high Output tubes can be divided into two broad classes classic pentode output tubes for medium power amplifiers and modern high performance pentodes for power amplifiers up to 80W output Low BIAS output tubes include 6L6 KT 66 EL 34 KT 77 5881 6 CA 7 High BIAS output tubes include 6550 KT 88 KT 90 KT 100...

Page 19: ...tubes only makes sense if the idle current is adjusted accurately as is clearly shown in Fig 1 Technical Data V 1 V 2 V 3 V 4 Regler für Röhre V1 V2 V3 V4 rot grün gelb How to set the BIAS Turn the Input selector knob 2 clockwise to the BIAS position to activate the measurement circuit pos 6 Signal input selection is disabled The 3 LEDs above each screw in the display panel show whether the BIAS s...

Page 20: ...100 6550 KT 90 See chapter 7 2 These tube types do not have to be operated at a high BIAS setting they will work perfectly well on the low setting However certain loudspeakers may benefit from the higher BIAS current as it will increase the damping factor and provide slightly better control of the movement of the speakers LED graphs BIAS yellow green red BIAS low BIAS high Brightness of the LEDs l...

Page 21: ...e 3 2 New untested output tubes should be allowed a longer warm up period You should adjust these tubes after about 20 minutes 7 5 Running in All OCTAVE equipment is subject to a 48 hour soak test at the factory to burn in the tubes The tubes are preselected for use in each particular model New tubes can take up to three months to run in and start sounding their best Daily use is beneficial in spe...

Page 22: ... equalization guarantees absolutely natural tonality of the phono preamplifier Traditional equalization topologies lacking effective subsonic filtering and carrying out the equalization within the negative feedback loop can never achieve better than average sound quality particularly as subsonic interference will cause substandard reproduction of the lower registers Two phono boards are available ...

Page 23: ...g the musical reproduction clearer throughout the entire frequency range The amplifier remains unaffected by mains variations and interferences due to the noise filtering characteristics of the capacitors 12 1 The Black Box option Black Box Indicator LED High current plug The LED illuminates continuously when the power amplifier is on The LED goes out when the protection circuitry trips This is no...

Page 24: ...and if the V 70 SE is powered down through Ecomode on The Super Black Box is equipped with a rapid discharge circuit which discharges the unit s electrolytics The yellow LED indicates that that this procedure is taking place The discharge circuit also activates if the SBB connecting cable is accidentally removed This is to prevent the SBB maintaining its charge when it has not been properly discon...

Page 25: ...s you have two grounded components connected to the V 70 SE You must now unplug your components in reverse order to find out which of them is grounded Usually the hum will still appear even when the problem components are switched off The ground causing the problem is always connected since it is not broken when the power switch is operated Now that you know which components are grounded you can d...

Page 26: ...fridges and 12V halogen lamps can produce strong radio interference when they turn on and off Depending on the wiring in your home this can result in clicks and pops in your loudspeakers To fix the problem Modern domestic mains systems with a separate protective earth PE will normally suppress this interference If you experience this type of switching interference you either have a poor protective...

Page 27: ...he BIAS screws to the extreme right and leave them there If you have not been able to adjust the BIAS satisfactorily turn the adjuster screw back to its extreme left position Driver tube heater fault When a driver tube heater fault occurs you will normally lose an entire channel depending on which driver tube system is affected by the faulty heater This can only be established by a visual examinat...

Page 28: ... protection system to trip Should this happen switch the V 70 SE off and replace the problem tube Faulty driver tube In very rare cases a problem with one of the driver tubes can cause the V 70 SE to switch off You can use the BIAS display to troubleshoot problems in the driver stage The procedure is the same as the one described earlier although the display will behave differently after the ampli...

Page 29: ...ohms Frequency response 20 Hz 70 kHz 40 W 1 3 dB 5 Hz 70 kHz 10 W 0 2 dB THD 0 1 at 10W 4 ohms Signal to noise ratio 100 dB 40 W Output Noise less than 300µV Optimal load impedance 3 16 ohms Minimum load impedance 2 ohms Gain 38 dB NFB 10 dB Tube set 4 x 6550 C Quiescent current output tubes 28 mA BIAS Low 34 mA BIAS High Preamplifier Input sensitivity 180 mV Line Level Inputs Input Impedance 50 k...

Page 30: ...SIONS 451 mm 150 mm 415 mm approx 490 mm with Black Box connection Diagrams THD at 4V into 4 ohms from 30 Hz to 20 kHz at a variety of BIAS settings Diagramm 1 Curve 1 BIAS adjusted correctly Curve 2 BIAS 10 out Curve 3 BIAS 30 out ...

Page 31: ... shows the low frequency extension of the V 70 SE linear to 10 Hz The loss at 20 Hz is less than 0 2 dB Graph 3 Noise spectrum Audio Precision A A FFT SPECTRUM ANALYSIS V 70 SE 5 V 4 Ohm 120 10 110 100 90 80 70 60 50 40 30 20 10 0 d B r A 20 20k 50 100 200 500 1k 2k 5k 10k Hz Noise spectrum at 1 kHz 5 W into 4 ohm there is no mains interference to be seen 50 Hz 200 µV 100 Hz 70 µV The k2 k3 k4 and...

Page 32: ... checked but these will generally last for well over 10 years 4 Does the V 70 SE have to have all of its tubes fitted In principle the V 70 SE will also operate without tubes It is sometimes useful to do this when testing the operation of the switching functions such as the selector switch remote control etc Of course it is not possible to play music under these circumstances For test purposes or ...

Page 33: ...e de We reserve the right to alter and improve the specifications in pursuit of better OCTAVE logo is a registered trade mark of Andreas Hofmann Copyright by Andreas Hofmann Reproduction in whole or part is prohibited edited EN2010 ...

Reviews: