NEW Hifi Class A headphone amplifier Kit base on A1 amp with protection circuit

Description

Product Detail:
100% in good condition
Assembled board:  we will soder and tested it well.
PCB Size: 160mm*110mmX1.6mm
Works Voltage:  recommend AC15V-0-AC15V
HV-1 Highlights:
1. The power triodes are connected in parallel to improve the driving force and control force, and the sound field is wider; it effectively solves the problem that the original A1 circuit promotes the weak intermediate frequency and poor control force of the AKG and Senhai series headphones, and the effect is very obvious!
2. 300MV earphone special protection circuit,
3. Omron power relays have larger contacts and copper sheets than small signal relays, and the signal loss is lower.
4. Separate power supply for the op amp in the AMP to improve the separation degree
5. Optimized ground processing, higher signal-to-noise ratio
HV-1 Hearing Summary
Three-stage balance, neutral and mellow, suitable for various types of headphones, "All-match King" headphone amplifier
Basic parameters:
• effective Vp-p 23.47
Frequency response, 20 HZ-20 KHZ (+ 0.01, 0.09),
signal-to-noise ratio:-90 DB or below,
the dynamic response, more than 91 DB
• total harmonic distortion (THD) : < 0.007%
• intermodulation distortion: < 0.007%
• stereo separating degree: > 88 DB (1 KHZ)
• suitable 32-600ohm load.
Main materials:
Original ST33078N dual op amp, STDB139-140 power transistor
Japan ALPS 27 type Potentiometer.
1/4W 1% precision metal film resistor
Omron G2R - 2 12V Relay 700MV Protection circuit,7 seconds delay connect function.
Package include:   HV1 Headphone amplifier kit  ( board )  X 1    (inlcude the ALPS Potentiometer)
The suitable power transformer link :
https://www.ebay.com/itm/325306923969
Note:
Please allow minor deviation due to manual measurement.
Due to the difference between different monitors, the picture may not reflect the actual color of the item.
Shipping:
Shipping Estimated Delivery Time
1.Economy(without tracking): 11-35 working days
2.SpeedPAK(with tracking): 8-12 working days
3.EMS(with tracking): 7-10 working days, need to pay extra shipping cost
4.DHL(with tracking): less than 7 working days, need to pay extra shipping cost
For faraway region or countries, the transit time may be longer than Overall Transit Time Frame.
Notes, the delivery time may vary due to public holidays, natural disasters, customs issue and other unexpected impact, etc.
Customs Declaration:
Import duties, taxes and charges are not included in the item price or shipping charges. These charges are the buyer’s responsibility.
Please check with your country’s customs office to determine what these additional costs will be prior to biddingying.
Payment:
We accept
PayPal ONLY
currently. Payment must be made within 3 business days.
Return & Refund:
Returns are accepted within 30 days.
Please read the item description and check the pictures carefully before bidding. Return or refund is available only if item DOA or there's error in item description
causing the item not fitting your need. In such cases, seller pays for all related shipping cost if any.
Returns are also acceptable if buyer purchased this by mistake and item still in good condition for reselling. Buyer is responsible for all related shipping cost.
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