Reference Series - Headphone Amplifier - NJC Audio

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Reference Series - Headphone Amplifier
Reference Quality Headphone Amplifier/Preamplifier
Why use a headphone amplifier?...
The standard headphone sockets on speaker amplifiers or CD players are not a very good way of connecting reference headphones, they may allow sufficient volume levels, but this has nothing to do with “properly” driving that headphone.

A quick inspection inside these pieces of equipment, often reveals a very basic circuit for the headphone output, with many speaker amplifiers simply having a tap from the speaker line with resistors, some may go a little further & have a low cost op-amp based circuit, however these are quite often very basic in design using lower grade components. A dedicated headphone amplifier is designed for use only with headphones, as such it provides a pair of headphones with all they need in order to be properly driven, a poorly driven headphone can often sound flat or lifeless.
Reference Quality Sound...
Our reference headphone amplifier delivers a true reference quality sound that is both neutral & uncoloured, having a completely even frequency response regardless of whether the headphones are 25ohms or 600ohms, retaining all the musicality & dynamics with power that makes music so much more enjoyable.

Being neutral in this way avoids many of the usual pairing problems, the amplifier basically allows you to hear how your headphones are supposed to sound.

We have built these amplifiers for many customers from enthusiasts who just enjoy listening to music, to voice over artists & home recording studio owners, it is the result of years of design & perfection, therefore the amplifier has gained a reputation for its sound quality & attention to detail when it comes to build quality.
Three stage adjustable gain to suit any headphone...
High power is not always required, especially when using very sensitive headphones, therefore the amplifier has a three position gain switch at the rear of the amp, this allows you to fully customise the power output to perfectly match any type of headphone, any of the three gain settings can be used regardless of input level.
High power for the most demanding headphones...
The reference headphone amplifier has been designed to meet the requirements of all headphones & has been extensively tested with a majority of popular models from Sennheiser, AKG, Beyerdynamic, Fostex, HiFiMAN  etc, including the hard to drive HE-6, of which the headphone amplifier effortlessly drives with plenty of headroom in reserve so musical transients are never restricted or compressed.
Headphone amp capable of driving every headphone
Soft start feature eliminates any turn on/off transients...
The amplifier also features a unique soft start, this eliminates any turn on/off transients & helps to prolong component life, it is a feature often commented on & appreciated by owners of the amplifier.

High quality components for performance & high reliability...
Inside the main aluminium chassis you will find some of the very best components, these have all been chosen not only for their performance, but also their reliability over the more common & cheaper components often used. Vishay Dale precision resistors are used throughout along with various other high quality components from Panasonic, Alps, Wima etc. Furthermore all components are only sourced from UK & US official distributers.
A high quality preamplifier...
The amplifier can also be used as a very high quality pre-amp, the gain can also be adjusted to match the input sensitivity of any power amp, in recent tests this has proved to be an excellent feature & allows all of the qualities of the amplifier to be transferred to active studio monitors or a home Hi-Fi speaker system.

Designed to compliment our matching Reference DAC...
The amplifier is a perfect match for our Reference Series - 24bit DAC which ensures a perfect source to ensure you get the very best performance from any headphone you decide to use.
More information can be found in our downloadable PDF
Technical Specifications...
Headphone Impedance Range: 8 ohms to 600 ohms (or higher)
Recommended Input Level: 150mV to 3.0V (1.0-2.0V recommended)
Preamplifier Output Level: 500mV / 1.0V / 2.0V (adjusted via gain switch)
Preamplifier Output Impedance: 600 ohms

Frequency Response: 10Hz - 50kHz (-1dB @ 50kHz)
Total Harmonic Distortion: (32 ohms / BW=80kHz / unweighted) <0.002% (1kHz)  /  0.003% (10kHz)  /  0.003% (20kHz)
Stereo Crosstalk: -83dBu (1kHz)  /  -75dBu (10kHz)  /  -70dBu (20kHz)
Maximum Output Power: (Both channels driven) 3.7W (22 ohms)  /  3.1W (32 ohms)  /  2.2W (50 ohms)  /  195mW (600 ohms)
Input Impedance: 12K
Headphone Output Impedance: (Ref 1kHz / 600ohms) 1.3 ohms

Warranty: 3 Years from date of purchase
Dimensions/Weight: 210mm x 115mm x 70mm  
/  1.4Kg (inc transformer)
Items Supplied: Reference headphone amplifier, external mains transformer, instruction booklet, test results & receipt

* Test equipment professionally calibrated to meet national standards

Frequently Asked Questions...
Question: Can I connect the headphone amplifier to my active studio monitors?
Yes you can, many of our customers use the "Pre-Out" on the headphone amplifier to connect to various active speakers, it is a feature that we often receive positive comments on.

Question: Does your headphone amplifier have enough power for the HiFiMAN headphones, particularly the HE-6 SE?
We have a wide range of headphones here in the workshop, including the original HiFiMAN HE-6 which shares the same sensitivity ratings as the new SE version, so I can say with certainty the amplifier has more than enough power to drive the HE-6, as a result they do sound excellent. It is also worth mentioning that the amplifier has the power output where needed (around 50ohms), you have to be wary when comparing specs as some manufacturers like to quote very low impedances, sometimes as low as 8 ohms! where an otherwise fairly low powered amplifier can then appear to be more powerful, when in actual fact at 50 ohms (which covers a lot of planar headphones) the power output can often be significantly less, sometimes down to a hundred milliwatts or less, this is why we quote various impedances in our specifications.

Question: I use the Sennheiser HD800 but also own some Shure in-ear phones, is it safe to use the latter with your amp or is it too powerful?
We do have a some owners that have mentioned using in ear type phones, while an amplifier is not technically required for these it is suprising how many have reported back to let us know how much of an improvement they have found, since the amplifier has variable gain you can adjust the power to suit any headphone, including the most sensitive in ears where the low gain setting will work perfectly & we find that medium gain is ideal for the HD800.
Pricing & Ordering Details...
Price: £495 + delivery
Delivery: £16.55 (Tracked/Insured)*
Build time: 10-12 days

Payment is by 10% deposit
Final payment upon completion.
Payments handled securely by "PayPal"
*Delivery is to UK Mainland only

To place an order please contact us at ""
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Quality British Engineered Audio Equipment
NJC Audio is a registered trademark #3525643
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