I'll have to look at your build. Like 6l6, I couldn't get my power supply box within 3 feet of the Pearl 2 chassis.
Russellc
Pass DIY Addict
Joined 2000
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Pass DIY Addict
Joined 2000
Paid Member
Here's the top side Ground regimen on the topside of the PASSDIY boards -- note that within the yellow circle is a somewhat high impedance connection between the copper "pour" and the preamplifier's grounded components.
If you flip the board over, the power supply components are all connected to a ground plane and this is again connected with a high impedance trace to the signal side of the board and grounding regimen.
If you flip the board over, the power supply components are all connected to a ground plane and this is again connected with a high impedance trace to the signal side of the board and grounding regimen.
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Can these be used, found in my parts bin
Attachments
First test run of of my Pearl 2:
- I've used 2 pcs. matched k369 as inputs and k117 for the LTP in second stage.
- Not completely hum dead quite at "full throttle", but nearly (whatever that means), i.e. power transformer and PCB in same casing get surprisingly well along. I need to do a little work at rectifier bridge probably. Either "Quasimodo" approach or just head under arm capacitors across diodes approach.
- I run slightly less current (around 7 mA) in the FET at the output. I think it got a bit hot at 10mA, and output offset adjustment became sensitive to temperature.
- Omitting of C7 is a must. That took some time (Note to self: Read entire build thread next time).
- I'm embarrassed using boards from an Ebay "PCB copycat pusher" . At least, they are not from Wayne's gerber files I can tell, because then there would be no error in the layout
(but it it could be fixed). I was tempted because they were inside EU. Long story short: I will use the original stuff and close my eyes for ridiculous customs handling fee next time.
- From fist impression sound is very good. I'm surprised about the firmness of bass. I've had to cheat in the RIAA compensation with design like Le'Pacific to get enough bass, but the Pearl2 is very good in that respect without "cheating". Maybe due to cojones of the MOSFET at the output. At least I think it sounds great.
Have any with a successful standard Pearl 2 build measured the noise level with a 47k cartridge load resistor, what can I expect? Thanks
- I've used 2 pcs. matched k369 as inputs and k117 for the LTP in second stage.
- Not completely hum dead quite at "full throttle", but nearly (whatever that means), i.e. power transformer and PCB in same casing get surprisingly well along. I need to do a little work at rectifier bridge probably. Either "Quasimodo" approach or just head under arm capacitors across diodes approach.
- I run slightly less current (around 7 mA) in the FET at the output. I think it got a bit hot at 10mA, and output offset adjustment became sensitive to temperature.
- Omitting of C7 is a must. That took some time (Note to self: Read entire build thread next time).
- I'm embarrassed using boards from an Ebay "PCB copycat pusher" . At least, they are not from Wayne's gerber files I can tell, because then there would be no error in the layout
(but it it could be fixed). I was tempted because they were inside EU. Long story short: I will use the original stuff and close my eyes for ridiculous customs handling fee next time.- From fist impression sound is very good. I'm surprised about the firmness of bass. I've had to cheat in the RIAA compensation with design like Le'Pacific to get enough bass, but the Pearl2 is very good in that respect without "cheating". Maybe due to cojones of the MOSFET at the output. At least I think it sounds great.
Have any with a successful standard Pearl 2 build measured the noise level with a 47k cartridge load resistor, what can I expect? Thanks
Attachments
Hi, I am debugging my Pearl 2 boards. I am powering the preamp +-39V from a pair of lithium batteries.
The music come thru but there is a lot of noise. It is unusable as is. Using my oscilloscope's FFT function, I have measured 60Hz noise on the output. My turntable is a Rega Planar 2.
Using a Parasound Zphono phono preamp, I have no problems listening to the Rega turntable.
What magic is happening in the Parasound that is not happening in the Pearl 2?
Since, I am using batteries to power the Pearl 2, any ideas on how to get rid of the 60Hz noise? I am using RCA right and left from the turn table, so the chassis grounds should be connected.....I think.
It could be my scope that is adding the noise, it is a cheap Rigol o-scope.
Any ideas would be much appreciated!
The music come thru but there is a lot of noise. It is unusable as is. Using my oscilloscope's FFT function, I have measured 60Hz noise on the output. My turntable is a Rega Planar 2.
Using a Parasound Zphono phono preamp, I have no problems listening to the Rega turntable.
What magic is happening in the Parasound that is not happening in the Pearl 2?
Since, I am using batteries to power the Pearl 2, any ideas on how to get rid of the 60Hz noise? I am using RCA right and left from the turn table, so the chassis grounds should be connected.....I think.
It could be my scope that is adding the noise, it is a cheap Rigol o-scope.
Any ideas would be much appreciated!
Hello,
I want to change my Pearl 2 from its current MC setup to something useful for an Ortofon 2M Black because a buddy is going to use it for a while. Other than changing the loading resistance and capacitance as needed, I am planning on putting a 1kOhm resistor at R14 to lower the gain to 55 dB.
Are there any other recommendations I should consider to optimize it for the 2M Black?
Thanks,
Alan
I want to change my Pearl 2 from its current MC setup to something useful for an Ortofon 2M Black because a buddy is going to use it for a while. Other than changing the loading resistance and capacitance as needed, I am planning on putting a 1kOhm resistor at R14 to lower the gain to 55 dB.
Are there any other recommendations I should consider to optimize it for the 2M Black?
Thanks,
Alan