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Original OPA-5A KT88  tube integrated Amplifier Headphone output With Bluetooth

Original OPA-5A KT88 tube integrated Amplifier Headphone output With Bluetooth

Original OPA-5A
Price: $728.99 USD

On-time Delivery and One-Year Warranty.

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Product characteristics:

  • The machine adopts high quality PCB welding to maintain stability and stability.
  • Two EI type output transformers with high quality broadband and high quality Z11 core are used.
  • Design of ring type power transformer specially designed for this machine
  • In the former stage, two 12AU7 vacuum tubes were used, and two KT88 vacuum tubes were used for class a single ended power amplification. The quadrupole KT88 circuit adopts the working mode of the quadrupole, which fully reflects the unique vigorous and vigorous personality of KT88.
  • Input has BALANCE/RCA/ Bluetooth selection.
  • Headphone output can choose four core balanced output and 6.5 head output.
  • Function of external speaker
  • Boot up silent delay function (about 30 seconds)
  • The volume potentiometer uses the Japanese ALPS (ALPS) 27 potentiometer.
  • Easy installation of plug type vacuum shield

The output mode of headphones is variable voltage output.
Output impedance: speaker 6 ohm headset 64 ohm
The output impedance of the earphone is balanced: 64 Omega 6.5 output 32 ohm.
Electronic tube KT88 is used for poplar and 12AU7 for dawning.

Functional description
Input part
Balance and RCA / Bluetooth mode are selected. Balance input is converted into unbalanced signal by high quality op amp, and is adjusted by volume potentiometer and input to amplifier circuit.

Output part
It has external speaker function and headphone output function. The headphone can choose four-core balance output and 6.5-head single-end output. The four-core balance output is isolated and amplified by the output transformer. The balance signal of positive and negative waveforms is driven by special technology.

Circuit description:

  • The first stage uses a double triode 12AU7 preamplifier and a cathode resistor connected in parallel with a capacitor of 100 mu. The aim is to obtain a better low frequency response and a faithful sound base.
  • The second stage is also driven by a double triode 12AU7 with a cathode output mode, in order to have a better low resistance to drive KT88.
  • The third stage KT88 adopts self biased bias transistor mode and AC ignition power supply mode.
  • Power transformer and output transformer are specially designed and customized for the machine, using high-quality wide-band sound and high-quality Japanese Z11 core.

Technical parameters:

  • Rated output power: external speaker output: 8W + 8W (4-8 ohm load).
  • Balanced headphone output: + 500, 500, 500, 500, 000 (32 Ohm).
  • Single ended headphone output: 1000MW + 1000MW (32 ohm load)
  • Whole machine frequency response: 20Hz to 50kHz (-1.5dB)
  • Harmonic distortion: 0.5% (1kHz)
  • Signal to noise ratio: 89dB
  • Input sensitivity: 230mV
  • Input impedance: 100K
  • Left and right output balance: <0.5dB
  • Use vacuum tube: 12AU7 X2, KT88x2
  • Working conditions: temperature: 0 ~ 40 ~ humidity: 20% ~ 80%
  • Storage conditions: temperature: -20 ~ 70 C humidity: 20% ~ 90%

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2. Please note that we are open Monday to Sunday between 8:00 Am to 24:00 PM Beijing Time.


1. We only accept Paypal,Escrow,Credit card.
2. Please pay within 7 days of order.


1. We send out items within 48 hours and give you the tracking numbers.
2. Delivery by DHL, UPS, FedEx, EMS in 3-7 business day.Free shipping only by China Post Air Mail ,usually you will receive in 15-55 business day, or sometimes even longer.
3. All items come from no smoke store and special care.
4. Shipping way will depend on your order quantity,sample order will be sent by China post.

Return & Refund:

1. In case you received a wrong item, Items must be returned in its original and unused condition & must also be in its original box and packing.
2. We do not allow refunds or exchanges because of change of mind. Please read all description provided as a guide before you bid. While every step has been taken to ensure that we ship out correct item, there will be occasion when you receive items that are different from the description. In such case, we ask that you contact us immediately so we may remedy the situation. Your satisfaction is important to us and we value your business.

Note: During holiday ,pls allow us to response you early next week ,kindly not leaving negtive/neutral feedback or make dispute/claim out of our working hours, thank you for your cooperation.