It sounds like your bias is either too high or too low. Probably too low but you need to check it and make sure you have enough heat sink. You may also want to check the Pass Labs forum as I am sure there is a few over there that have had the exact same problem as you.
I have one and loved it, it should not distort with a normal CD player's input. Unfortunatley it is loaned out to a friend.
I have one and loved it, it should not distort with a normal CD player's input. Unfortunatley it is loaned out to a friend.
Bride of Zen distortion
I had a similar problem when I built this design. I overcame it by raising the voltage at C102+ above the design level of 8V. Do this very carefully and go no further than needed to loose the distortion. Small advancements of P102 acheive this.
Regards
PS let us know how you get on
I had a similar problem when I built this design. I overcame it by raising the voltage at C102+ above the design level of 8V. Do this very carefully and go no further than needed to loose the distortion. Small advancements of P102 acheive this.
Regards
PS let us know how you get on
do you use all parts as shown in the original schematic above.............or have you something changed?
the psu voltage should be near by 60 volt
.......and the drain volts (drain to ground) are 20v..........to 30v , this gives you a drain current from 40ma to 30ma with a 1k drain res.
have a look at the zener diode at the input ,the side with the ring should be connected to the 100 ohm res.
yes,you can put the volume pot at the input..........or on the output. i have tried that out and both worked fine (with my cdplayer).
greetings
the psu voltage should be near by 60 volt
.......and the drain volts (drain to ground) are 20v..........to 30v , this gives you a drain current from 40ma to 30ma with a 1k drain res.
have a look at the zener diode at the input ,the side with the ring should be connected to the 100 ohm res.
yes,you can put the volume pot at the input..........or on the output. i have tried that out and both worked fine (with my cdplayer).
greetings
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have a look at the zener diode at the input ,the side with the ring should be connected to the 100 ohm res.
/QUOTE]
.........to the 100 ohm gate res (at the line with the 1uf input cap).
i use a little bit bigger source res that lowers the gain of the boz because my tube power amp doesn't need so much input volts.
/QUOTE]
.........to the 100 ohm gate res (at the line with the 1uf input cap).
i use a little bit bigger source res that lowers the gain of the boz because my tube power amp doesn't need so much input volts.
This thread should since long been moved to passlabs by the moderators, please.
Anyway, the BOZ clips badly when fed with the standard 2Vrms from a CDP. The input will only take just above 1Vrms.
Easy fix!
1 Do not go HIGHER on the bias voltage go LOWER! Run the BOZ on ca 7V bias as this adjusts current to ca 30mA(originally 40mA). Drain-voltage should then be 30V and you will get symmetric clipping at just above 2Vrms.
2 Another solution could be to lower gain as mentioned in a post above. The cicuit has a current feedback of 33dB and the relationship between source- and dran-resistor sets gain. A 150ohm source resistor will give you the 30mA and 30V with the original bias-voltage. Clipping at close to 3Vrms.
3 If you want to keep the circuit as is, B+ must be 80V. You will then get symmetric clipping at just below 3Vrms.
Anyway, the BOZ clips badly when fed with the standard 2Vrms from a CDP. The input will only take just above 1Vrms.
Easy fix!
1 Do not go HIGHER on the bias voltage go LOWER! Run the BOZ on ca 7V bias as this adjusts current to ca 30mA(originally 40mA). Drain-voltage should then be 30V and you will get symmetric clipping at just above 2Vrms.
2 Another solution could be to lower gain as mentioned in a post above. The cicuit has a current feedback of 33dB and the relationship between source- and dran-resistor sets gain. A 150ohm source resistor will give you the 30mA and 30V with the original bias-voltage. Clipping at close to 3Vrms.
3 If you want to keep the circuit as is, B+ must be 80V. You will then get symmetric clipping at just below 3Vrms.
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