Elekit TU-8800 Single Ended Pentode Power Amplifier/HPA Kit with Lundahl Transformers
The TU-8800 is a single-ended pentode power amplifier and headphone amplifier kit that supports many popular octal-base pentode and beam power tubes. By simply changing the power mode, 6V6, 6L6/EL34 and most of the KT series tubes can be used. The TU-8800 is the culmination of ELEKIT's best designs and circuitry from their previous amp models. You can learn more about the TU8800 in this interview with the designer, Mr Fujita or download the TU8800 brochure.
This is a version of the TU-8800 with the two stock transformers replaced with Lundahl LL 2783C transformers.
Included Upgrades from Stock
- Lundahl LL 2783C transformers
- Takman REX50G 2% Carbon Resistors (85 pieces)
- TKD 2CP601 volume potentiometer
Supports various pentode and beam tubes
Select from 3 power modes with the switch at the rear of the chassis (Low/Mid/High). The amplifier supports various commercially available pentode and beam tubes. Select Triode or Ultralinear modes again via a switch on the rear panel.
Active Automatic bias adjustment system
The amplifier features an ELEKIT original "Active automatic bias adjustment system". Depending on the selected power mode and tube type the correct level of bias current is set. The accuracy and stability of this feature has been improved from past models.
Stable NFB circuit for great audio quality
The NFB loop is separated to the output stage and voltage amplification stage for maximum amplifier stability. Especially for the output stage, cathode NFB is applied from the third winding of the OPT. This circuitry minimizes NFB and the amp achieves high stability without adjustment.
Ample space for larger coupling caps
Capacitors play an important role in sound quality. For the TU-8800, conductive polymer hybrid electrolytic capacitors and PP film capacitors are used. Although they are small in size, the PP film caps provide for very high performance. For those who wish to use other even higher quality caps, there is ample space provided on the PCB for mounting larger caps.
Power and Operation mode Switches at the top of the chassis
Using a combination of power mode (3 settings - High, Mid, Low) and operation mode (Triode, Ultralinear) many different tubes can be used:
- Low power: 6V6, 6F6, 6V6GT, 6F6GT
- Mid power: 7581, 5881, 6L6, 6L6GT, 6L6GC, 7027, 7027A, EL34, WE350B
- High power: KT66, KT77, KT88, KT90, 6550, 6550A, KT120, KT150
Selectable output levels for headphones
From low to high impedances, the headphone output level can be selected from a choice of 6 levels by simply changing the jumper location (see photo).
- Stock tubes: KT88x2, 12AT7x2
- Rated output: 12.5W+12.5W (KT88-HIGH mode, UL, THD 10%)
- Rated input : 360mV
- Residual noise: 90μV (IHF-A)
- Frequency response: 12Hz-55kHz (-3dB)
- Input impedance: 50kΩ
- Output impedance: 4-6.3Ω, 8-16Ω (Switch on the rear side)
- Input terminal: LINEx2 (LINE1, LINE2) : RCA jack
- 3.5mm stereo mini jack (common to LINE2, priority to LINE2)
- Output terminal: Headphone terminal : 6.3mm headphone jack
- Speaker output terminal: Gold-plated screw terminal (Banana plug compatible)
- Power voltage: AC115/230V 50/60Hz(3P inlet)
- Power consumption: 95W
- Dimensions: W350xH204xD324mm (incl. projections)
- Weight: Approx.12kg (excl. power cord)
Nice build and perfect fit! With robust output and reasonable replacement tube cost, it is a nice addition to our amplifier collection and in fact drives all our loudspeaker models with very good sound. Some parts replaced by "better" quality.
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