Mpp

[Joachim Gerhard]

If you like you can come to the L`Art du Son room and we have a chat. Would be nice to see you.

[gk7]

Cool, CU

For anyone who might attend the Klangbilder show too, it´s room 334 (third floor).

[Algar_emi]

Hi. I have a full set of measurements on the Paradise. Readings:
Gain: 61.4dB at 1Khz
Vout max: 30Vpk-pk
THD at 1Khz (Ref 1Vrms): 0.06%
Noise measured with HP3581A
Noise at 1Khz (input in 50 ohms, 10Hz BW): -99dBV (-92dBV in 30Hz)

Noise floor, see included picture, in red my Clio system noise floor, the white is the Paradise, input terminated in 50 ohms, no shield or enclosure, but using the pre-reg and RC-filter supply. First supply 120Hz peak at -74dBV. It will be probably lower with a separate supply enclosure, put away.

1Khz FFT spectrum. The supply noise is higher there because the preamp is connected to the CLIO system. I always have this kind of error in measurement of phono preamp. It will be lower with an actual cartridge.

RIAA Curve, see table included
Well close to text book perfect, with 0.2dB almost at all frequency. Since my signal generator is not perfectly frequency stable, neither perfectly flat in amplitude, these are pretty good results.

The Paradise has excellent measured specs. Now time to start building the enclosures...

[Algar_emi]

Here both schematics preamp and regulator with a lots of reference voltages readings. May be useful while troubleshooting your preamp.

[Salas]

There is discrepancy from 1.5KHz upwards between channels. What is better to mod for that? Some impedance ratios, or the 11n caps?

[Joachim Gerhard]

I would tune the caps. To get a handle on the output impedance of the mirror is harder.

[Joachim Gerhard]

Algar, i see mostly PSU harmonics. That should go down a lot when the circuit is in the cabinet plus correct shielding. Otherwise it looks good.

[Salas]

Originally Posted by Joachim Gerhard

I would tune the caps. To get a handle on the output impedance of the mirror is harder.

Open loop blues...but hands on, we like hands on.

[FdW]

Originally Posted by Algar_emi

Here both schematics preamp and regulator with a lots of reference voltages readings. May be useful while troubleshooting your preamp.

To PSU looks perfect to me. The preamp also (but that’s not mine to judge ) Most of the mains related peaks will be gone if the measurement equipment is disconnected, when the RAW PSU has its own box, and when the preamp has its own box. (as Joachim noted)

[MiiB]

Algar...

you have to get rid of the hum....!! all the harmonics you see at you FFT is from the 60 Hz hum you have..

And when you measure the Paradise you need to terminate the input with a lower resistor. the 50 ohm termination has more noise than the stage in itself.

But I agree, these are a clear hint of the technical qualities of the phono-stage...Not too bad..!