DO IT YOURSELF
TUBE PREAMPLIFIERS
CAUTION! HIGH VOLTAGE!
Observe safety precautions when working with high voltage!
"Golden Middle" reserves the right to make changes in products
not affecting the basic technical characteristics.
Hi-Fi PREAMPLIFIER FOR HEAD-PHONES Loftin White EL86 Polam in triode
with transformer output stage and variable output voltage from 2,5 up to 20 V.This preamlifier can be used in any audio system.
TECHNICAL SPECIFICATIONS :
Input signal level = 250 mV
Input impedance : 50 KOhm
Output signal level with different load resistance :
I...2,5 V (minimum load resistance 16 Ohm)
II...5 V (minimum load resistance 100 Ohm)
III ...10 V (minimum load resistance 300 Ohm)
IV...20 V (minimum load resistance 600 Ohm)
THD on each loads : not more 0,25%
S / H not less -80 db
Maximum ouput voltage 40 V (3 KOhm)
Frequency response @ 1 V outputs with different load resistance : 15 - 45000 Hz
High stability power supply
Curcuit diagram
DIY :
Tubes : EL86 Polam õ 2 pcs; ECC88 õ 1 pcs ;
Curcuit diagram ;
Output transformers potted into black boxes õ 2 pcs ;
Power transformer potted into black box õ 1 pcs
Choke (not potted) õ 1 pcs ;
Mounting board 3PM20-11 õ 2 pcs (1 pcs predrilled for mounting tube sockets) ;
Complete set of all necessary parts for assembling according curcuit diagram
(capacitors , ceramic tube sockets, all resistors) ;
Volume control ;
Input sockets RCA and output sockets Jack 1/4 (6,3 mm) ;
Power cord.
All parts are spread out on separate packages with instructions of appropriate numbering
on the circuit.
All tubes are are tested up for usage in this preamplifier.
All transformers have multi-colored outputs.
Color of each output is signed and specified on the circuit (it is impossible to confuse).
Hi-Fi PREAMPLIFIER FOR HEAD-PHONES Loftin White 6S19P
with transformer output stage and variable output voltage from 2,5 up to 20 V.
This preamlifier can be used in any audio system.
TECHNICAL SPECIFICATIONS :
Input signal level = 250 mV
Input impedance : 50 KOhm
Output signal level with different load resistance :
I...2,5 V (minimum load resistance 16 Ohm)
II...5 V (minimum load resistance 100 Ohm)
III ...10 V (minimum load resistance 300 Ohm)
IV...20 V (minimum load resistance 600 Ohm)
THD on each loads : not more 0,12%
S / H not less -80 db
Maximum ouput voltage 40 V (3 KOhm)
Frequency response @ 1 V outputs with different load resistance : 15 - 45000 Hz
High stability power supply
Curcuit diagram
DIY :
Tubes : 6S19P õ 2 pcs; ECC88 õ 1 pcs ;
Curcuit diagram ;
Output transformers potted into black boxes õ 2 pcs ;
Power transformer potted into black box õ 1 pcs
Choke (not potted) õ 1 pcs ;
Mounting board 3PM20-11 õ 2 pcs (1 pcs predrilled for mounting tube sockets) ;
Complete set of all necessary details for assembling according curcuit diagram
(capacitors , ceramic tube sockets, all resistors) ;
Volume control ;
Input sockets RCA and output sockets Jack 1/4 (6,3 mm) ;
Power cord.
All parts are spread out on separate packages with instructions of appropriate numbering
on the circuit.
All tubes are are tested up for usage in this preamplifier.
All transformers have multi-colored outputs.
Color of each output is signed and specified on the circuit (it is impossible to confuse).
