I have aquestion regarding the 100pF cap (C1). When I tried to replace the original Panasonic film cap with a styroflex all I got is a loud hum. Any ideas why such a cap doesn't seem to work in that position?
Isn't C1 supposed to be 10,000uf not 100pf?
Edit: Sorry you are talking about C1 on the MC pre right?
Jeff
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Hi, Does anybody have Pearl PCB's they would like to sell. I need 4 but 2 will do for now?
Regards to you all
Regards to you all
Hmmm, those Lundahl LL9206 trannies are nice and small !
Looks to me that they are propely shielded, so I can connect the metal shield to the ground 😕 I want to build them together with my pearl in a metal case. Will this be sufficient against the horrible hum
Looks to me that they are propely shielded, so I can connect the metal shield to the ground 😕 I want to build them together with my pearl in a metal case. Will this be sufficient against the horrible hum

I honestly hope this will be the last time I'm closing my Pearl
fugly !

A few things here for the archive.
1. I changed the 2sk170's for (SMD) BF862.
It gives a little bit more gain and clearer sound.
2. I also use the 9V battery option instead of that noisy zenerdiode.
I installed a Reed relais that is fed by the powersupply and that switches the battery off if the Pearl is shut down. This way the battery will last longer, it's only in use when the Pearl is powered. The sound is purer than using the zener.
1. I changed the 2sk170's for (SMD) BF862.
It gives a little bit more gain and clearer sound.
2. I also use the 9V battery option instead of that noisy zenerdiode.
I installed a Reed relais that is fed by the powersupply and that switches the battery off if the Pearl is shut down. This way the battery will last longer, it's only in use when the Pearl is powered. The sound is purer than using the zener.
Attachments
i always wanted to try the battery option - never got around to it.
nice hacking! The Pearl is a classic.
nice hacking! The Pearl is a classic.
A few things here for the archive.
1. I changed the 2sk170's for (SMD) BF862.
It gives a little bit more gain and clearer sound.
Did you match those?
....
1. I changed the 2sk170's for (SMD) BF862.
It gives a little bit more gain and clearer sound.
....

I matched them only to have equal gain for both channels, not to have the same gain as the 2sk170 did. It worked fine.
quote Andrew T. :
The BL is a 6 to 12mA device the 862 is 10 to 25mA device.
Look at the BL 12mA example of transconductance. You will see they show 30 to 40mS from 5mA to 10mA Id.
Choosing a very high BL, or a low V grade, will give a similar range of Yfs, if you run them at similar high Id.
quote Andrew T. :
The BL is a 6 to 12mA device the 862 is 10 to 25mA device.
Look at the BL 12mA example of transconductance. You will see they show 30 to 40mS from 5mA to 10mA Id.
Choosing a very high BL, or a low V grade, will give a similar range of Yfs, if you run them at similar high Id.
Hello,Also there are 2 points on the board called Star1 and Star.
These 2 points need to be connected with a piece of wire.
This connects Audio Star Ground with ground plane.
Sorry for my late reaction, but I got the complete kit just en few days ago and I'm building it now. What I don't get is why wasn't "Star" connected to "Star1" right away on the PCB? There is room for it?
Or is it an option to connect "Star1" to GND and leave "Star" connected to 0V?
Hello,
Sorry for my late reaction, but I got the complete kit just en few days ago and I'm building it now. What I don't get is why wasn't "Star" connected to "Star1" right away on the PCB? There is room for it?
Or is it an option to connect "Star1" to GND and leave "Star" connected to 0V?
What kit?
Russellc
I got the complete kit a few days ago. That kit contains 2 mainboards, 2 MC pre boards and 2 PSU boards. This threat is about the MC pre boards, so that is also what my question is about. Once again, Why wasn't "Star" not connected to "Star1" when there is room on the PCB to do so?
Is it better to connect "Star1" to GND and leave "Star" connected to 0V (so not shorting 0V to GND via this connection)?
Is it better to connect "Star1" to GND and leave "Star" connected to 0V (so not shorting 0V to GND via this connection)?
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