Paradise Builders

[hesener]

Originally Posted by analog_sa

After running some tests it appears both polarities of the regulator contain some noise around 7-8MHz. Put together a quick 317/337 replacement and it appears all of this is now gone. It's getting late and i hope i am not wrong about this, but so far it looks that at least in my build it was the regulators oscillating.

The offset issue certainly remains.

Interesting..... in the R1 betabuild, we had 4 boards where the regulators (CCS part) was oscillating , and stubbornly so. But these were built around LM317/337 CCS, cascaded with bipolars, and when Frans changed that to the discrete design for R3 that was all gone.....

[Bksabath]

So how s Sheffield then

[Marra]

Hesener is there any chance of posting a picture of your input loading and grounding arrangement?Thanks Marra.

[Bksabath]

Sorry to But in Buss of stars on mine

[Marra]

Thanks Bk

[Bksabath]

You welcome
Actually I forgot to put smiley on previous post as picture is upside down

And maybe is worth looking at how the output cables to the Pre-amplifier are arranged
As the Pre amplifier is earthed trough the mains I may be worth cutting the screen at the preamplifier ends and that is why I just sqibled Out on those

By buss of star I mean
Star one all wire to the same point enclosure, board 1, board 2,maybe the ground cable from the arm, this then out to a single cable to the PSU or star 2 as follows: Cable to star 1, ground from pre reg 1,ground from pre reg 2, eart of enclosure and this out to the main plug.

Please note that there are no other earth connection to the cartridge as 4 independent wires are used and that same turntables, Like my RPM4 used to be before surgery, have the screens of the Phono cables connected to earth at the turntable end and this can cause a loop and maybe noise pick up (I say maybe as ground loops issues are a real pain in the bottom.)

[hesener]

Hi marra and all,

here the updated assembly guide , check out the last two pages on case layout and grounding. we hope it helps....

[Waly]

Originally Posted by PMA

You did not get the point.

Calm down, I guess I did. So, what you posted is a MM amp, not the MC amp you claimed here. Or similar, with a 20dB LT1028 opamp in front. Set aside this flies in your own face (by using a bipolar opamp in front, with the inherent bias current flying in the MC), any comparison with the Paradise falls flat.

BTW, there is much more than "can keep DC output voltage at the value close to Vos voltage of the servo opamp as long as voltage output of the DC servo opamp does not go to saturation" in a servo. I'll let you find out what's happening when the forward and reverse servo loop gains are comparable. BTW, you admit that "For the DC servo is an integrator, it may happen that the whole system's output DC would fluctuate, as it depends on behavior of the circuit that is inside the DC servo loop". At least that, it's a good starting point .

[FdW]

Originally Posted by hesener

Hi marra and all,

here the updated assembly guide , check out the last two pages on case layout and grounding. we hope it helps....

Looks good Alfred

[Take5]

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