Preamplifier Manual 13 March 2012 - Music First Audio

Classic PreamplifierOwner’s manual

IntroductionCongratulations and thank you for purchasing the Music First Audio Passive Magnetic Preamplifier.This original device controls up to six sources and attenuates level. It sits betweenstereo source devices such as CD players, turntables etc. and power amplifiers. A rotary switchon the front panel selects inputs and the level is controlled by another rotary switch.Level is controlled by a custom designed and made transformer via the front panel mountedELMA 24 position switch. This method offers many advantages over other attenuation solutions.Conventional passive volume attenuation relies on resistive networks selected via multi wayrotary switches. Introducing transformers into the equation also introduces considerable physicaland therefore audible improvements:Transformer isolates components, breaking ground loop problems and reducing noiseTransformer matches impedance between components.Transformer affords superior transfer of musical energyA +6db switch means the unit is passive with gain, so amplifiers can be driven to theirmaximum efficiency by components that otherwise might require active boosting.The effects of the unit are obvious from the first listen, the sound flows from source to destinationwithout any colouration allowing music to be heard as it was intended without any interferencefrom active components.In order to get the most out of your Passive Magnetic Pre-amplifier please take time to read theConnection, Grounding switch and Operation sections of this manual. Failure to do so may resultin damage to connected equipment.

ConnectionThe rear panel houses all input and output connections. Inputs are situated to the right andoutputs to the left. The inputs should be connected to the outputs of source devices (CD player,cassette player etc) at line level. The phono/ RCA inputs are for connection to unbalancedequipment, while the XLR inputs are for connection to balanced equipment.As a general “rule of thumb” if the output of a piece of source equipment is on XLRs then it isbalanced and if it is on phonos/ RCAs, then it is unbalanced. This is not always the case butshould give a good starting point.The outputs of the unit are located on the left hand side of the back panel. The XLR output isbalanced and the phono/ RCA output is unbalanced. Because the transformers convert balancedand unbalanced signals, these outputs are always the same, regardless of which input type isused.Only ever connect one output (balanced OR unbalanced) at a time, use of both outputs atonce is NOT recommended and may cause damage to any equipment connected to thePassive Magnetic Pre-amplifierPlease note - Connection of faulty equipment to the unit will cause malfunction, ensure alldevices connected are in good working order.

ConnectionSourcesPassive pre amplifierPhonostagePlease note:Turntables should be RIAA equalised and stepped up to line level before thePassive Magnetic Pre-amplifier. If in doubt please contact mfaudio via e-mail:info@mfaudio.co.uk

The grounding switchOnce equipment has been connected as described, it is necessary to select grounding optionswith the rear-mounted switch. This three position switch controls whether the output ground isfloating (unconnected) or connected to the internal ground reference (and to input ground). In thecentre position the output ground is floated. In the RCA position, the RCA outputs are groundedand in the XLR position, the XLR outputs are grounded.The setting of this switch is entirely dependent on the rest of your system. A simple procedure willdeduce how it should be set.1. Ensure your amplifier is turned off and connect it’s input to the output of the Passive preamplifier2. Connect all your source equipment as described above and switch it on (do not play anymusic at this point).3. Set the grounding switch to the centre (Lift) position and the Passive pre amplifier levelcontrol to (minimum)4. Turn on your amplifier and turn up the volume control (if there is one) a little.5. Gradually increase the level control on the Passive Magnetic Pre-amplifier. You shouldhear nothing (a little “hiss” from source devices is normal). If you hear a loud “buzzing” or“humming” sound, turn down all level controls and switch your amplifier off.6. Set the grounding switch to RCA or XLR (depending on the type of output you are using)7. Repeat steps 4 and 5. The buzzing should now have stopped.You might find that the switch requires a different setting for each piece of source equipment. It isworth trying the above procedure for each separate source.Please note: The input grounds are connected to the internal reference via resisters (this is todrain static voltage on source equipment ground which prevents “clicks” and “pops” whenswitching sources). Input F is hard grounded (no resister); this input is best suited to sources thatare particularly noisy (e.g. digital television receivers etc).

Operation1. Before use ensure the level control is set to (minimum level)2. Switch on the source devices (CD player, tuner, turntable etc.)3. Switch on the amplifier and set the amplifier volume control (if there is one) to themaximum necessary listening level.4. Select the source device.5. Set the Passive pre-amplifier level control to the desired listening levelPlease note:If the source is to be changed always return the level control to (minimum level) beforechanging the source to avoid damage to loudspeakers and amplifiersAlways turn amplifier levels down and power off before powering down sources, again toavoid damage.The +6dB switchA great feature of the Passive Magnetic Pre-amplifier is the +6dB switch, which allows the unit toactually amplify signals. When in use 6 decibels of gain are present. This means sources thatmight normally require active boosting can be accommodated in a passive solution.

Burn inYour new pre-amplifier should sound extremely good out of the box, but to obtain the very bestresults we recommend a period of "burn in", sometimes also called "break in" or "running in".This process will happen by itself with use of the pre-amplifier over the first two or three weeks.Try to play some of your quieter recordings more often during the burn-in process, so that youcan use the pre-amplifier volume control at higher levels (which helps the burn-in process).If possible, we recommend the following procedure for very best results:1. Connect a source which will play a constant signal (for example; a CD player on repeat,or a tuner)2. Connect to your power amplifier(s) and listen to confirm that the source is playing.3. Switch off your power amplifier(s) and unplug them from the mains power supply*.4. Then turn the volume control of the preamplifier all the way up to maximum (0dB)5. Leave this set up running for as long as possible. We recommend 100 hours for bestresults, but customers have reported continued improvement over 300 hours and beyondThe principal is that the sound signal is passing through the pre-amplifier with the volumecontrol on full, so it passes through the entire transformer winding system. The pre-amplifiermust be connected to the power amplifier (to provide a "load"), but the power amplifier doesnot need to be switched on.If you have another pre-amplifier, you can daisy chain them together for the burn in period sothat you can let the signal pass through your Music First Audio pre-amplifier at full volume anduse your existing pre-amplifier to control the actual sound volume during the running-in period.The signal path should be:Source > Music First Audio Pre-amplifier > second pre-amplifier> power amplifier,This ensures the Music First Audio Pre-amplifier will pass the signal at the highest level, whichis best.*We recommend disconnecting the mains power to the power amplifier to serve as a reminderthat the pre-amplifier is turned up to maximum. This way you avoid forgetting that the system isset up for burn in and accidentally switching on your power amplifiers, which would result in avery loud sound and possible damage to your loudspeakers!Warning: turning a power amplifier on while the pre-amplifier level control is set atmaximum could result in damage to connected equipment!!For any further advice, please contact us at info@mfaudio.co.uk

MaintenanceThe unit should be cleaned with a soft dry cloth. NEVER use abrasive cloths or cleaning solution.For stubborn stains, slightly dampen the cloth with water.Contacts and connecters can be cleaned with proprietary switch cleaners (Servisol etc.) althoughthe use of switch lubricants is not recommended.SpecificationInputsOutputsControls4 x Stereo unbalanced2 x Stereo balanced1 x Stereo unbalanced1 x Stereo balancedLevel (24 position rotary switch)Source (6 position rotary switch)+6db (2 position toggle switch)Grounding (3 position toggle switch)Z Out0dB volume setting+6dB volume setting-20dB volume settingSource Impedance + 600R(1k Source = 1600R)Source Impedance x 4 + 900 R(1k Source = 4900R)Source Impedance / 100 + 33 R(1k Source = 43R)

TroubleshootingSymptomNo SoundProblemNo source playing/ selectedSolutionEnsure the source is playingEnsure the correct source isselectedPassive Pre amplifier level toolow/ offTurn up the level control on thePassive Pre-amplifierAmplifier not on/ level too lowLoud “buzzing or “humming” sound Ground selector incorrectly setEnsure the amplifier is on andany volume control is upCheck that the groundingswitch is correctly set (see“The grounding switch”)For any further advice, please contact us at info@mfaudio.co.ukWARNINGIn no event shall the manufacturer be liable for any damage, direct, indirect orconsequential of any type or any expenses or losses resulting from the use of this product.Contains no user serviceable parts, refer servicing to qualified personnel only.Do not expose the unit to moisture, excessive heat or cold.The contents of this manual are correct at the time of going to press. The manufacturerreserves the right to change the specification and features without prior notice.

Customise and upgrade your preamplifierWe’re confident that your preamplifier will give you many years of listening pleasure.Of course, it is possible that your needs may change for one reason or another.All Music First Audio products are made by hand here at our Hastings, UK workshop.This means we are able to offer an extensive customisation and modification service.We’re happy to offer these options as modifications and upgrades to existing units.Upgrade to MKII transformersWe can install our MKII transformers in your Classic Preamplifier. The MKII transformers offerextended level handling together and low frequency response.Install silver transformersOur 99.99% silver winding wire offers different sonic characteristics, useful if your system or yourtastes change.Add Home Theatre Bypass/ Pass throughWe can add HT pass-through to any input of your preamplifier. This feature allows a dedicatedtwo channel system to work seamlessly with a home theatre.Add remote level controlOur MKII and Reference models offer infra red remote control of level using a stepper motorsecured to the rear of the level control. There are no additional components in the signal path soaudio performance is not affected in any way.We can add this facility to your Classic Preamplifier.Change the input/ output configuration of your preamplifierBalanced and unbalanced inputs and outputs make it easy to connect your preamplifier to a widerange of sources and amplifiers. But, if your requirements change, we can reconfigure the rearpanel connections of your preamplifierInstall a Tape Output or full Tape Monitor facilityWe can add a transformer isolated source direct output to your preamplifier for recording. We canconvert any of the inputs to act as a dedicated Tape Monitor input.Add Custom Brass Damping Panels for added weight and massBeautiful Brass Plates can be fitted to the top of your preamplifier and engraved with your name.These panels, together with rubber gaskets and a steel panel underneath the lid add weight andmass to the top of the preamplifier and this damping prevents vibrations reaching the transformers.This is just a selection of the available options. We’re also happy to work with you on completelycustom solutions so please don’t hesitate to contact us for further information: info@mfaudio.co.uk