NVA INT250 User manual

NVA INTEGRATED AMPLIFIER – INT250, INT400, INT 400SA - USER INSTRUCTIONS
Thank you for purchasing this NVA Integrated Amplifier. The functions and operations of all
NVA amplifiers are deliberately simple. However, it is essential that you read through
these user instructions prior to installing the amplifier into your system. Failure to do so
may result in accidental damage to the amplifier circuit.
Always remember, NVA is different! No attempt is made to add output compensation
networks, such as an inductor or parallel capacitor network or even fusing. Therefore, the
amplifier is not unconditionally stable, and requires the use of our own 'LS Series' low
capacitance speaker cable, which is supplied with your amplifier. Use of non-NVA speaker
cables will invalidate the NVA warranty.
The reward for following these instructions... is a beautifully pure, open and musical
presentation. Welcome to the NVA sound!
Paul Tiernan (Director)
Page 1 – Placement & reasonable use
Page 2 – Putting the system together, cable management
Page 3 – Dismantling the system, cleaning
Page 4 – Diagrams, notes
Page 5 – Optimise your NVA system
Page 6 – Contact NVA

Placement & Reasonable Use
At all times during use, you must ensure adequate ventilation space around the top and
sides of the amplifier (minimum 3 inches) for air to circulate. The amplifier must sit on it's
own feet (removing or replacing the feet will void our warranty). Do not place the amplifier
on top of anything that generates any level of heat.
NVA amplifiers are designed for domestic use at normal domestic listening levels. They are
not PA or 'party' amplifiers. Playing the amplifier at very high volumes into difficult loads for
extended periods of time will cause the amplifier to overheat, and may cause catastrophic
failure of the amplifier, beyond economic repair.
The only 'running in' required is to leave the amplifier powered on at all times. The
capacitors will be fully formed after the amplifier has been left on for 72 hours. You can still
play music as often as you want during the run-in period – at first, the amplifier may sound
'tight',
NVA amplifiers do not contain an automatic thermal cut out device. We advise monitoring
amplifier temperature if you are uncertain in any way about the volume levels that you wish
to listen at. Put most simply, if the amplifier is uncomfortable to touch, it is too hot and
should be switched off, immediately.
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Putting The System Together For The First Time
1. Lower the volume control(s) to minimum on the amplifier (do not connect any
cables, yet)
2. Power on the amplifier from the switch on the rear panel
3. Connect sources to the amplifier inputs
4. Connect speaker cables to your speakers FIRST
5. Connect speaker cables to the amplifier starting with black
6. Check the selector switch is in the right position for your intended source, play
some music and gradually turn up the volume
It is very important not to short the loudspeaker plugs, as permanent damage can
result.
Cable Management
•Never twist or tie cables together – let them run independently
•Keep signal cables away from power cables
•Allow space between cables (proximity creates unwanted capacitance)
•Ensure all connections are secure and not stressed / stretched
Keeping The Amplifier Powered On
For best performance, we recommend that you leave the amplifier powered on at all times,
unless you are going to be away for an extended period. Electricity consumption is very
low at idle. If you decide you need to power down, switch off the music source, make sure
the volume is set to minimum then power the amplifier off from the switch on the rear
panel. It is not necessary to disconnect any cables.
Powering Back On After Turning Off
Switch off music source (failure to do this may damage your equipment), lower the volume
control(s) to minimum on the amplifier, then power the amplifier on from the switch on the
rear panel. You may notice a small 'bump' type noise through the speakers when you
power back on. This is normal and will not damage your speakers.
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Adding / Removing Inputs
Powering down of the amplifier is NOT required but NEVER unplug inputs while the
amplifier is playing music
1. Switch off music source (failure to do this may damage your equipment)
2. Lower the volume control(s) to minimum
3. Add / remove source input cables, as desired
4. Check the selector switch is in the right position for your intended source, play
some music and gradually turn up the volume
Dismantling The System
1. Switch off music source (failure to do this may damage your equipment)
2. Lower the volume control(s) to minimum on the amplifier
3. Remove the speaker cables from the amplifier FIRST starting with the red
4. Disconnect sources from the amplifier inputs
5. Power off the amplifier from the switch on the rear panel and wait for 5 minutes until
the transformers have completely discharged (the LED will remain on while this
happens).
Cleaning
Dust with a lint-free cloth. To remove fingermarks, apply a spray of Windowlene to a fine-
grade microfibre glass cloth and then wipe the acrylic surfaces. Never use alcohol based
cleaning products.
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1. Input selection knob – with pointer to indicate position.
2. Volume control knob – with pointer to indicate position.
3. Power-on LED (red).
1. Power-on switch.
2. Captive mains lead – required for compliance with Class II regulations. Do not
remove / replace / modify.
3. Speaker outlet sockets red (live) – one per channel.
4. Speaker outlet sockets black (ground) – one per channel.
5. Tape Rec output – can be used to connect a headphone amplifier or tape recorder.
6. Line level inputs (6 of).
Notes
All of the line inputs are the same sensitivity. If you wish to use a turntable, you will need a
separate phono-stage, such as our P1 or P2, which you will then connect to any one of the
six line inputs.
The Tape Rec output can be factory configured as a Pre Out facility (for connecting to a
separate power amplifier, or for connection to the low-level inputs of an active subwoofer).
Only the NVA speaker cables supplied with your amplifier should be used. Use of
other speaker cables will invalidate your warranty.
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How To Optimise Your NVA System
DO:
Allow adequate ventilation all around the amplifier(s).
Use tables and other furniture that allow for plenty of space between components and
easy access when setting up.
If the phono stage head unit and power supply have to be side by side due to space
constraints, make sure the phono stage output sockets are on the opposite side to the
power supply case(s).
Keep hi-fi signal cables away from power cables.
Allow space between cables (close proximity can cause unwanted capacitance).
For best sound the amplifier should be left powered up. Electricity consumption is very low.
It is for this reason that the power switch is located on the back panel, where it may not be
easy to reach.
Try a Balanced Mains Unit. UK mains quality can be very poor. There's a strong possibility
that you won't hear your system at it's full potential until you try our BMU.
DONT:
Don't use tightly spaced metal racks. If you need a dedicated rack, buy one that is deep
enough to allow easy access from the rear and with plenty of spacing between the
shelves.
Don't sit head units (Phono 2 / 3, AP10H) on top of their power supplies. Use the umbilical
leads provided to keep as much distance between them as possible without stretching the
leads or stressing the connections.
Never twist or tie cables together - let them run independently.
Don't forget to check out the extensive archive of NVA advice, discussion and user reviews
at our Hi-Fi Subjectivist Forum www.hifisubjectivist.org
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Contact:
NVA Hi-Fi
Unit 2
The Old Goods Yard
Commercial Road West
Coxhoe
Durham
DH6 4HJ
United Kingdom
www.nvahifi.co.uk
[email protected]
www.hifisubjectivist.org
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