Thanks Ben Mah - your explanation is very helpful and instructive!
I also built a Nutube Korg B-1 and I was thinking about swapping the BA 2018 out for that with the Pearl 2. It sounds great and has higher gain which works with the F6 I built. Given that it's power requirements are positive only - I will probably supply it's power from the original wall wart and not the Pearl 2 boards.
Thanks again!
I also built a Nutube Korg B-1 and I was thinking about swapping the BA 2018 out for that with the Pearl 2. It sounds great and has higher gain which works with the F6 I built. Given that it's power requirements are positive only - I will probably supply it's power from the original wall wart and not the Pearl 2 boards.
Thanks again!
Google translation:
Hi Wagner
Please post only in English, it's one of the Forum Rules
diyAudio Rules
George
You can simply reverse the cartridge polarity. If turntable is your only source, the easiest way is to reverse the loudspeaker polarity.
If the Pearl 2 is your only phono amp, then swapping the polarities on the phono cartridge will allow you to leave the speaker leads in their normal position. That way you can change between a phono source and a CD source without having to change anything else.
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Also my 834p has an inverting stage at output (cathode follower) but my DAC has the inverting option, so in my situation it's easier to invert speakers polarities. If you have detachable headshell on your turntable, you can use one cartridge with reverse polarities for the Pearl and another with normal phase for another non-inverting phono preamp
Yet another way (if you don't mind diving back into your Pearl with a soldering iron, or if you haven't built it yet) is to swap the signal and earth leads on the rca inputs. Solder the signal lead to the rca earth lug and the earth lead to the rca centre pin. It would be the same as swapping the polarity on the cartridge.
Hello vcec thank you . but i don't think that will work. 1st the signal will go to the mass so in the chassis .2em the masses being common there will no longer be any stereo . I don't want to reverse the cell or the speaker. I want to modify the pearl circuit to have the right phase.thank you for having an answer from an electronics technician
Cartridge normally is not connected to gnd: there's no continuity between the chassis (you have separate GND cable on turntable for this purpose) and the cartridge until the phono preamp. So, inverting polarities at inputs of preamp would be the same thing as inverting the cartridge leads.
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Pearl 2 new build completed
I've recently completed a new build of the Pearl 2, details here:
mpbarney - Pass pearl 2 Phono Preamp
I've recently completed a new build of the Pearl 2, details here:
mpbarney - Pass pearl 2 Phono Preamp
Attachments
Yes, this preamp reverses polarity. The easiest way to correct this is to reverse the phono cartridge leads. Reversing your speaker leads accomplishes the same thing, but if you use any other sources (tuner, tape, DAC), those will now be out of phase.
Mike
Mike
That’s what I did. Works fine fine for me. I really didn’t have other options as I used the dual chassis approach and have no other DC point to connect. When I built a BA-3 as preamp I used raw dc at the rectifier but that’s not really an option with my Pearl II.
You’ll have a lot of voltage to contend with so a higher value resistor in front of the LED will be in order (if you want a softer look). I also prefer a 3mm blue colored LED’s rather than the clear blue for a more diffuse look. I’m learning from my mistakes…in the Pearl II (one of my first projects) I used two 5mm clear blue LED’s without enough resistance and they’re like headlights. I plan to revisit some day with a transistor based dimmer and swapping out the LED’s. Can’t seem to get back to it with so many other projects.
New LED are so incredibly efficient that they need microamperes, not milliamperes to light them at a level suitable for our uses, particularly if you are looking at them straight-on.
I’d start with 1K/volt of supply for the LED resistor, (24Kohm to begin) and that might be too much. Don’t hesitate to add more series resistance to get it to a level you like, it’s just a lightbulb.
I’d start with 1K/volt of supply for the LED resistor, (24Kohm to begin) and that might be too much. Don’t hesitate to add more series resistance to get it to a level you like, it’s just a lightbulb.