Gyrator parts:
R11 right 973R left 1K01
R7 right 984R left 993R
R8 right 475K left 475K
R9 right 9,86Meg left 9,93Meg
R6 right 498,2R left 499R
Trimmer both 5K
C3 100nF
M2 & M3 both LND159
U3 both IXTP08N100D2
J1 both 2SK3557-7-TB-E
D1& D2 both Zener 15V 1/2W
R11 right 973R left 1K01
R7 right 984R left 993R
R8 right 475K left 475K
R9 right 9,86Meg left 9,93Meg
R6 right 498,2R left 499R
Trimmer both 5K
C3 100nF
M2 & M3 both LND159
U3 both IXTP08N100D2
J1 both 2SK3557-7-TB-E
D1& D2 both Zener 15V 1/2W
Why 2SK3557?
It's 35mS FET.
BF862 has 45mA, BSH111 has 380mS, so output impedance would much lower.
BTW 2SK3557 hasn't input protection, so D1,D2 mandatory.
It's 35mS FET.
BF862 has 45mA, BSH111 has 380mS, so output impedance would much lower.
BTW 2SK3557 hasn't input protection, so D1,D2 mandatory.
BF862 EOL, I followed Ale's advice to use 2SK3557. Ok I'll install D1 & D2.
Why this big difference in level between channels not reflected at measurements?
Why this big difference in level between channels not reflected at measurements?
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Soldering the zeners I discovered the 100nF cap one leg desoldered, now both channels sound with the same level and I'm the man most happy of the world🤗
In your preamp, yes.
The emerging operating point will be little different, and R.C. regulator must be set again.
The emerging operating point will be little different, and R.C. regulator must be set again.
Bela could I use 15K-300R OPT in place of Ale's hybrid mu-follower to listen my Sennheiser HD600 300R?
Do you have at least 150-160H primary inductance with 30..40mA current tolerance?
I highly doubt it.
If yes, you have about 200R output impedance.... and only few mW output power on 300R.
I highly doubt it.
If yes, you have about 200R output impedance.... and only few mW output power on 300R.
Secondary
Off Load Voltage 23,1V
Winding resistance 0,64 ohms
Primary
Winding resistance 55,03 ohms
Off Load Voltage 23,1V
Winding resistance 0,64 ohms
Primary
Winding resistance 55,03 ohms
If I remember correctly, you use R.C. V9 regulators.
Rod recommended 3V voltage overhead for this.
If you use 8R as filament bias resistor, the recommended minimum raw voltage for R.C. regulator:
(1.25A*8R)+7.5V+3V= 20.5V
If the values in PSU (PT secondary voltage - 23.1V? -, PT DCR - 1.195R? - , chokes DCR) are correct, the secondary RMS current is 2.29A .. below the 2.4A .... but probably will overheat.
Rule of the thumb: use at least twice power (current) capacity transformer for large/r/ current as calculated.
See schematic in #35 post.
Rod recommended 3V voltage overhead for this.
If you use 8R as filament bias resistor, the recommended minimum raw voltage for R.C. regulator:
(1.25A*8R)+7.5V+3V= 20.5V
If the values in PSU (PT secondary voltage - 23.1V? -, PT DCR - 1.195R? - , chokes DCR) are correct, the secondary RMS current is 2.29A .. below the 2.4A .... but probably will overheat.
Rule of the thumb: use at least twice power (current) capacity transformer for large/r/ current as calculated.
See schematic in #35 post.