Elekit TU-8550 Tube Pre-amplifier Kit with Phono Stage

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Elekit TU-8550 Tube Pre-amplifier Kit with Phono Stage

The TU-8550 is an all-stage vacuum tube preamplifier kit with a built-in phono equalizer amplifier, sold with valves. It's a definite step up from the popular TU-8500. 

The phono equalizer amplifier uses a CR-type RIAA equalizer circuit with a reputation for straightforward and smooth sound quality. It also utilises quadral volume to keep the noise floor down to a minimum. To explain, high gain is sometimes required for low-level sound sources or where the amp's input sensitivity is low. However, the high gain of a pre-amplifier can create the problem of noise. With this VOLUME-GAIN locking system, the gain decreases as the sound volume is reduced (approx. 1.4 times) and increases when the volume is increased (approx. seven times),  putting the residual noise problem to rest. The result is low noise and love volume levels.

Elimination of hum noise. In the power supply, fast recovery diodes are used for the HT supply. It utilises a slow start MOSFET circuit, providing a stabilised supply. All valves are supplied with an LDO-regulated (low drop-out) DC supply for the heater supply, further reducing hum.

REC-OUT built-in. Signals selected by the selector feed directly into the record-out so that you can connect to a recording device.

Two output RCA pairs for PRE-OUT. You can connect up to 2 power amps, which is great for bi-amping

Ample space for larger coupling capacitors. It can accommodate a capacitor of 20mm diameter x 57mm length


  • Line level ​​section: 2 x 12AX7, 1 x 12AU7 Single-ended input/output
  • phono equalizer amplifier section: 2 x 12AX7, 1 x 12AU7 CR type RIAA equalizer amplifier
  • PSU: DC regulated, MOSFET type slow start constant voltage power supply

Line Amp Stage Unbalanced input/output, continuously variable gain type

  • Maximum output voltage 20Vrms (1kHz) 
  • Maximum gain Approx .17dB (x7)
  • Frequency response 5Hz to 200kHz (-3dB)
  • Residual noise (IHF-A) 15μV (the sound level at max)
  • Residual noise (IHF-A) 6.5μV (the sound level at the middle)
  • S/N ratio (IHF-A) 130dB (the sound level at the centre)
  • S/N ratio (IHF-A)126dB (the sound level at the max)

Phono equalizer amplifier part

  • Maximum output voltage] 20 Vrms (1 kHz)
  • Gain (1 kHz) 29 dB
  • Residual noise 50 μV (IHF-A)
  • RIAA deviation Within ±0.5 dB (20 Hz to 20 kHz)
  • Input resistance 47 kΩ (MM)


  • Input/output terminals PHONO IN: RCA jack, for MM cartridge, 47kΩ
  • The mains voltage input CIA IEC socket can support 100Vac, 115Vac, 200Vac and 230Vac, so it can be used anywhere in the world.
  • Rated power consumption 23W
  • Main unit dimensions W 352 × H 66 × D 298 mm (including protrusions)
  • Main unit Weight is about 3.9kg (when completed)
  • LINE IN: 4 lines LINE 1, 2, 3: RCA jack
  • LINE 4: 3.5mm stereo phone jack (front)
  • PRE OUT: 2 RCA jacks (parallel Output)
  • REC OUT: RCA jack one system

PRICE (1 off)
£935.00 +vat +p&p

For those who wish to buy the component upgrade kit, you will need to add the following to your cart when purchasing your kit.


Part Position Quantity
RES-25-05W-100K: 100K 0.5W Audio Note Tantalum Resistor  R103/R203/R110/R210 4
RES-NM25-05W-1K0: 1K 0.5W Audio Note Tantalum Non-magnetic Resistor R102/R109/R202/R209 4
SUP8-0,47: 0.47uF 600Vdc Mundorf MCap Supreme Capacitor C108/C208 2
PH9001-6103J: 0.01uF 600Vdc Jupiter Copper Foil, Paper & Wax Capacitor C107/C207 2



Part Position Quantity
(REX50-290) - 470R 0.5W TAKMAN Carbon Film Resistor R133/R233/R114/R214 4
(REY50-570) - 100K 0.5W TAKMAN Metal Film Resistor  R127/R227 2
RES-25-05W-220K: 220K 0.5W Audio Note Tantalum Resistor R128/R228 2
(PRP-1/2-330) - 1K 0.5W PR9372 Metal Film Resistor R125/R225/R118/R119/R120/R121/R218/R219/R220/R221 10
(REX50-460) - 12K 0.5W TAKMAN Carbon Film Resistor R124/224 2
ZN630-0,47: 0.47uF 630Vdc Mundorf MCap ZN Capacitor C111/C211 2
S3Q470N: 0.47uF 1000Vdc Solen FEP Tin Foil / Teflon Film Capacitor C112/C212 2
CAP-100-R-330U-25V: 330uF 25Vdc Audio Note Kaisei POLAR Electrolytic Capacitor  C110/C210 2



Part Position Quantity
CAP-100-R-22U-350V: 22uF 350Vdc Audio Note Kaisei POLAR Electrolytic Capacitor C101/C109/C113/C301/C201/C209/C213/C302/C303 9


TOTAL PRICE for all upgrade parts on 09/01/23 - £454.38 +vat +p&p

See our two instructional Youtube videos below on how to construct the Elekit TU-8550

PDF datasheet

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