Just a note to builders.
Do not just blindly use trimmers for R7 and R8. Know the reasons for MAYBE wanting to use them. Ultimately you would want to use fixed resistors here. If this is not explained clearly in the BOM document, please let me know to remove any ambiguity.
Do not just blindly use trimmers for R7 and R8. Know the reasons for MAYBE wanting to use them. Ultimately you would want to use fixed resistors here. If this is not explained clearly in the BOM document, please let me know to remove any ambiguity.
2SK1530 Bias
My aleph J with toshiba 2sk1530 is working, but the bias is to high.
The voltage drop at the source resistors doesn´t go lower than 550mV.
I use 2K potentiometers for bias and offset.
I also tried a 5K potentiometer for bias, but bias is still not getting lower.
The offset is allmost zero, but the temperatur is to high and i would prefer a voltage drop of 450mV as recomended.
My F5 is working fine with 2sk1530, 2sj201, so i didn´t expect any problems.
Do you have a hint what i have to do?
My aleph J with toshiba 2sk1530 is working, but the bias is to high.
The voltage drop at the source resistors doesn´t go lower than 550mV.
I use 2K potentiometers for bias and offset.
I also tried a 5K potentiometer for bias, but bias is still not getting lower.
The offset is allmost zero, but the temperatur is to high and i would prefer a voltage drop of 450mV as recomended.
My F5 is working fine with 2sk1530, 2sj201, so i didn´t expect any problems.
Do you have a hint what i have to do?
Did you jumper the R27A position though?
Yes, good point. We are all assuming you have read the building guide by 6L6.
Yes, i guess some people successfully tried the toshibas in the aleph J, so eventually there is help here.
The point i didn´t understand was, with 2K pots i reached 550mV at the end of the range of the pots. So i thought 5K would help me, but the bias didn´t go any lower with them, their might be a limit here?
Haha, i could use some pc cooling vents on the amplifier and hope the toshibas will last.
Thanks for your help.
The point i didn´t understand was, with 2K pots i reached 550mV at the end of the range of the pots. So i thought 5K would help me, but the bias didn´t go any lower with them, their might be a limit here?
Haha, i could use some pc cooling vents on the amplifier and hope the toshibas will last.
Thanks for your help.
6L6 thats interesting, so i use a voltmeter for R27, to a least get the left and right channel at the same current gain?
Do i have to lower or to rise R27 to get lower bias, so that i just move the adjustment range of R8 in the right direction?
So i might for example use 50K or 100K for R27, if i don`t want to use pots.
Do i have to lower or to rise R27 to get lower bias, so that i just move the adjustment range of R8 in the right direction?
So i might for example use 50K or 100K for R27, if i don`t want to use pots.
Jim
This is the thing that bugs me about this circuit that I can't understand. I always thought that the bias of the output stage can only be determined by:
1. The value of R7 and the current flowing throught it via Q1
2. The current flowing through Q3
My understanding is/was that the CCS only regulates current through the output stage as the current demand changes.
This is the thing that bugs me about this circuit that I can't understand. I always thought that the bias of the output stage can only be determined by:
1. The value of R7 and the current flowing throught it via Q1
2. The current flowing through Q3
My understanding is/was that the CCS only regulates current through the output stage as the current demand changes.
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