Classique – Phono Valve Preamp Amplifier With Passive RIAA Using 12AX7 / 12AU7 – DIY Kit

£300.00

Free Delivery

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Checkout the WHITE PAPER for the Classique – 12AU7 12AX7 Phono Valve Preamp Amplifier With Passive RIAA – DIY Kit.

We Love Vinyl Too…

And we hope all vinyl lovers will be excited about this new kit.

This is an all-valve DIY 12AX7 and 12AU7 phono amplifier kit that enables you to use your moving magnet record player with your integrated amplifier.

Similar concept to all designs in our Classique range, this DIY phono amplifier uses traditional design and topology which have been used and tested for many decades. It is powered by two 12AX7 valves for passive RIAA equalization and a single 12AU7 valve as the buffer stage. You will only need one phono PCB per amplifier to power both left and right channel.

We designed this DIY phono preamp kit to be in the exact same size as all other kits in the Classique range. The mounting plate, which can be ordered separately, will enable you to setup the kit as we designed it.

It is worth noted that designing a phono amplifier in general is pretty tricky due to its nature. This is mainly caused by the fact that all components have to be setup accurately to make sure that the RIAA equaliziation is done correctly. The components are of very low tolerance value where it matters. Additionally, there is also the challenge of noise (internal and external).

So, we have made it easier for everyone to setup this DIY phono preamplifier kit. It is designed to use electronic components that are readily available from your usual electronic shops. They are readily available which means it will be easy to maintain your amp.

There are only two PCB’s involved. One for the phono amplifier, and the one for the power supplies.

The power supply PCB is responsible for supplying the high voltage as well as the (DC) low voltage for the heater filaments.

We also included two transformers in this design, one for the high voltage and the other for the low voltage to decouple any noise from each other.

Remember that you will need to purchase the enclosure/mounting plate separately if you wished.

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SKU: KIT2 Category: Tags: , , , ,

Description

Specifications

  • Common cathode class-A gain stage with no feedback, passive RIAA equalization and cathode follower buffer stage
  • 2 x 12AX7 for RIAA correction and 1 x 12AU7 for buffer stage
  • Cartridge Compatibility: Moving Magnet
  • Input Impedance: 47k ohms (set by input resistor – can be changed accordingly)
  • Output Impedance: 322 ohms
  • Gain: 39 dB gain @ 1kHz
  • Distortion: <0.05% @1kHz
  • Equalization: RIAA +/- 0.5 dB, 40Hz to 30kHz (measured)
  • Regulated 12VDC heater power supply elevated to 90V
  • Current draw: 24mAmp at 300VDC
  • Classic Dale grid resistor
  • Reverse-able main Phono amp PCB. Components can be soldered on the same side as the valves OR on the opposite of the valves. This feature enables builder to mount the board with valves outside chassis OR valves being inside of the chassis
  • Locally designed and made power transformers

Documentations / Downloads

The Components

The list below is the complete list for the kit.

  • 2 x power transformers with flux bands – locally made by primarywindings.com
  • 1 x integrated power supply PCB and components (for B+ and heater filament)
  • 1 x phono amplifier PCB and components (only one piece is needed for stereo channel)
  • All screws / nuts / bolts / spacers
  • Double pole single toggle power switch
  • RCA input/output terminals
  • IEC power socket with with internal fuse slot

The Kit

Following are the variation(s) of the kit:

  • Kit C = (Phono PCB + Components) plus (Power supply PCB +Components) plus (2 transformers) plus (all connectors and power switch)

NOTE: You will have to add the following items separately:

  • 2 x 12AX7 and 1 x 12AU7 valves
  • Enclosure (checkout our enclosures here)
  • Aluminium plate compatible with all our enclosures

Don’t forget to checkout the WHITE PAPER for the Classique – 12AU7 12AX7 Phono Valve Preamp Amplifier With Passive RIAA – DIY Kit.

Audio Analysis

Graph below shows the measured frequency response tested using 2 x Electro Harmonix 12AX7 and 1 x Electro Harmonix 12AU7:

Measured frequency response of the RIAA correction.
Measured frequency response of the RIAA correction.

IMPORTANT NOTES AND DISCLAIMER

This product is sold as a kit, which means that buyer would have to assemble all parts. Printed circuit boards (PCB) are not populated so all parts will have to be soldered onto the PCBs.

It is assumed that buyers would have the knowledge of:

  • soldering
  • assembling screws/nuts/bolts
  • highly skilled and knowledge of high voltage electric circuits and parts
CALEDONIAN AUDIO will take no responsibility on any injury or death as a result of the work conducted to assemble this kit. Please make sure that you know what you are buying and handling. If you have never done any electric and electronic work before we would strongly suggest that you consult us before buying this kit.

Additional information

Weight 0.2 kg
Dimensions 20 × 20 × 5 cm
Classique Phono Options

KIT A, KIT B, KIT C

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