Elekit TU-8550 preamp with phono stage

Elekit TU-8550 preamp with phono stage

Overview

This is a preamplifier kit with a built-in phono equalizer amplifier (MM cartridges), configured with tubes for all the signal stages. (In these two respects it differs from TU-8500).

Circuit description

The CR type RIAA equalizer circuit, which is considered to have excellent sound quality, is used. Furthermore, all time constant capacitors are DC bias superimposed, which is considered desirable for sound quality.

In the flat amplifier, a quadruple volume pot is used interlocking the volume control and gain control. If the input sensitivity of the power amplifier is low or the level of the sound source is low, a high gain is required for the preamplifier. However, the disadvantage of a high preamp gain is residual noise at low volumes. To overcome this, the TU-8550 uses a volume-gain linkage system in which the gain is lowered when the volume is lowered and increased when the volume is raised.

Volume and balance potentiometers are from the highly regarded Alps Alpine RK271 series.

Power Supply

The B power is rectified by a fast recovery diode and a slow-start stabilised power supply with MOSFETs provides better quality than tube type rectification. The A power supply (heater power supply) is also a full DC current system using LDO regulators to thoroughly eliminate hum noise.

Overview

This is a preamplifier kit with a built-in phono equalizer amplifier (MM cartridges), configured with tubes for all the signal stages. (In these two respects it differs from TU-8500).

Tube complement:

  • 12AU7 x 2 (Electro Harmonix)
  • 12AX7 x 4 (Electro Harmonix)

Circuit description

The CR type RIAA equalizer circuit, which is considered to have excellent sound quality, is used. Furthermore, all time constant capacitors are DC bias superimposed, which is considered desirable for sound quality.

In the flat amplifier, a quadruple volume pot is used interlocking the volume control and gain control. If the input sensitivity of the power amplifier is low or the level of the sound source is low, a high gain is required for the preamplifier. However, the disadvantage of a high preamp gain is residual noise at low volumes. To overcome this, the TU-8550 uses a volume-gain linkage system in which the gain is lowered when the volume is lowered and increased when the volume is raised.

Volume and balance potentiometers are from the highly regarded Alps Alpine RK271 series.

Power Supply

The B power is rectified by a fast recovery diode and a slow-start stabilised power supply with MOSFETs provides better quality than tube type rectification. The A power supply (heater power supply) is also a full DC current system using LDO regulators to thoroughly eliminate hum noise.

Regular price $1,695.00
Regular price Sale price $1,695.00
Sale Sold out

Customer Reviews

Based on 2 reviews
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C
Cheng Su
Eletkit TU-8550

Very good design for adding a gain port together with Volume Controller port.
It is a tube sound preamp that most people like perhaps.
One weak point on design is the Regulator's Heatsink for Tubes Filament is not big enough. It is very hot when in normal operation. If we use in a Summer time that will be overheat. End up in a long run may caused solder dry joint or creak solder on the Regulator IC.
Use only 12AX7s and 12AU7s.

M
Matthew Thomas
Having a Go

The TU-8550 preamp with phono kit was not cheap in anyway. A very high quality pre amp that would be very expensive as a complete unit. Very easy to follow and doing it in a group would be an advantage. The sound and feel of the unit is outstanding. Matt