Product Description
Price is for only one PCB and the components unsoldered without TUBE
(there is no instruction, part list , need DIY electronic basic. there is risk of failure if you do not know how the tube amp work.)
we can solder for you, just pay more US$10
PCB size 340mmx125mm, thickness 2mm, FR4 quality
Not including the tube
Using PCB circuit board to build tube amp is more simple, convenient, faster, easier . easy to adjust and better anti-interference ability, as long as connected to the input and output power transformer, then you can make a high-quality tube amp yourself. Highly recommend for DIY hifier
This board reference the classical TVA-1 push-pull circuit, classical and professional.
Note on Transformer: power transformers should be used high quality iron core (such as Z11), core specifications should not less than EI114 stacked thick 60mm, total power can not less than 250W.
primary input 0V-220V-235V, the secondary high-voltage output 0-320V (for EL34) -390V (for KT88) 0.4A or more (single power supply is ok, the board designed with full bridge rectifier), 0-100V 0.15A for negative pressure regulate,
4 pcs power tube filament power supply divided into two groups, each group 0-6.3V 4A,
ECC83 (12AX7) and ECC81 (12AT7) filament 6.3V-0-6.3V 2A one group
(filament voltage 3.15V-0-3.15V 2A one group if 6N2 and 6N1 on preceding stage tube).
output transformer configured to power more than 30W, primary impedance 5K-6.6K with ultra-linear tap, secondary impedance configuration according to your actual needs.
Note: must remember to connect to dummy load before power it!
1. power without tube, measure voltage of points (such as B + voltage (KT88 is 550V, EL34 is 400V), negative voltage, pre-tube screen voltage value, the power pole tube screen voltage values, etc. and record data, presetting gate bias to (KT88 is -60V, EL34 is -40V).
turn off power after no abnormality and then plug with tube voltage and also measuring points again, flow adjustment screen.
2.Adjust the screen flow: multimeter black pen ground (circuit board screw holes), playing at DC 20V, with red pen to measuring power voltage of 1 or 8 feet, adjust the 4 adjustable potentiometer, make the voltage of 1 or 8 feet of tube(when used KT88 can be voltage of 3.75V = 80mA,adjust the potentiometer to 2.82V when with EL34 at this current is 60mA ), adjust 4 pcs tubes to all same, you can adjust again after working normal some hours or some days later
3.The original circuit uses two ECC83 and two ECC81, you can also use two 12AX7 and two 12AT7.
Note on Transformer: power transformers should be used high quality iron core (such as Z11), core specifications should not less than EI114 stacked thick 60mm, total power can not less than 250W.
primary input 0V-220V-235V, the secondary high-voltage output 0-320V (for EL34) -390V (for KT88) 0.4A or more (single power supply is ok, the board designed with full bridge rectifier), 0-100V 0.15A for negative pressure regulate,
4 pcs power tube filament power supply divided into two groups, each group 0-6.3V 4A,
ECC83 (12AX7) and ECC81 (12AT7) filament 6.3V-0-6.3V 2A one group
(filament voltage 3.15V-0-3.15V 2A one group if 6N2 and 6N1 on preceding stage tube).
output transformer configured to power more than 30W, primary impedance 5K-6.6K with ultra-linear tap, secondary impedance configuration according to your actual needs.
Note: must remember to connect to dummy load before power it!
1. power without tube, measure voltage of points (such as B + voltage (KT88 is 550V, EL34 is 400V), negative voltage, pre-tube screen voltage value, the power pole tube screen voltage values, etc. and record data, presetting gate bias to (KT88 is -60V, EL34 is -40V).
turn off power after no abnormality and then plug with tube voltage and also measuring points again, flow adjustment screen.
2.Adjust the screen flow: multimeter black pen ground (circuit board screw holes), playing at DC 20V, with red pen to measuring power voltage of 1 or 8 feet, adjust the 4 adjustable potentiometer, make the voltage of 1 or 8 feet of tube(when used KT88 can be voltage of 3.75V = 80mA,adjust the potentiometer to 2.82V when with EL34 at this current is 60mA ), adjust 4 pcs tubes to all same, you can adjust again after working normal some hours or some days later
3.The original circuit uses two ECC83 and two ECC81, you can also use two 12AX7 and two 12AT7.
NOTE: assembled for your reference only: the price is not include tube
Welcome to visiting minishow0328 HIFI Audio store!
（we can combine shipping for you if you need other items）
we have DAC,amplifier,preamplifier,headphone amplifier,tube amplifier and other hifi DIY audio parts for selling.
if you want other parts but have not listing, you can email us,we will try our best to service you.
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We can promise here:
1. We do not sell fakes or defective item! We will reply all messages within 24 hours!
2. Every package will provide tracking number for free! We will arrange shipment in order, you can purchase without worry!
Please Note: If any import tax or duty is charged by custom office in your country, it is your responsibility!
(1) Most items in stock we will ship in 1-3 days after payment cleard(excluding weekend)
Some handmade/customized DAC/preamp finished board needs 3-10 days to prepare and burn-in.
(2) All packages under 2KG, we will ship by China Post registered airmail, with track number.
(normally takes 12-40 days to most countries)
if you want express need to contact us.
(3) All packages more than 2KG, we will ship by DHL express/FedEx express/EMS express/ SPSR express.
(normally takes 5-15 days,EMS takes more days).
and if any import tax or duty is charged by custom office in your country. you can ask them for more details. if you do not like express, please also contact us.
(4) please contact us if package not received in 45 days. we will help you to check.
(1) We accept PayPal only, we will ship your items after payment cleard.
and system will send Unpaid item case after 1 week if unpaid orders.
(2) Please confirm yoru shipping address and telephone number is correct and valid.
(3) Customers from Russia, please provide Full name and Shipping address in English. postal office request it.
Please don't hesitate to contact us if any queries or comments about our items or your problem.
All assembled/finished items: 1 year warranty provided,we acccept replacement or refund as your preference, just make sure the item in original condition and pay shipping cost.
