Pearls

[Val Lewton]

If you mean cascoding, the gain with a faily low resistance drain load will be nearly identical with a cascode or a non cascode circuit. I believe this confusion over cascodes and gain can be traced to a certain high volume poster who often makes technical errors in his post. I will save him the embaresment of mentioning his name. You probably should add a 500 ohm gatedamping resistor to the jfet for better RF immunity and sonics.

Val

[oliverniekamp]

Ah sorry, cascoding of course. Maybe a gate resistor could be worth a try, i didnt implement it because its not in the original aleph or ono circuits.

[hsort]

Hi oliverniekamp,
i had the same idea with 3 Stages.the new one i put in between the 2 original ones.but i got a penalty with distortion.i measured about 1 % with gain about 70 dB. so i will switch to a design like Borbely's one with one gates of the paralled fet's grounded and with ccs in the sources

[Saurav]

I forgot one thing, the circuit can oscillate or recieve radio signals, a 10pf styroflex in the pearl input and a 20 ohm resistor ín the output solve the problems.

Hi,

I've been trying to figure out RFI issues with my Pearl (and squealing noises that could be RFI or oscillations), so this is of interest to me. I assume you mean the cap goes in parallel from the input RCA to ground, and the resistor goes in series between the output pad and the output RCA? I got a lot of thr RFI out by shielding the power umbilical, but there's still a slight bit of noise left.

Thanks,
Saurav

[oliverniekamp]

saurav,yes you got the right positions, the oscillations can start at the input thats what the caps are for, the value could depend from the value of the input resistor, it rejects radio signals too. Im not shure about the reason for the oscilation from the input, i heard a loud hum, about 100 hz and it stoped when i solderded the capacitor in tne input.
There can be an oscillation on the output too, i guess it could be an oscillation between the output capacitor and the input cap from the connected preamp. I checked the values by trying, there are four pearls running in four hifi systems with different preamps and MC cartridges and there are no radio or other noises apearng.

[Saurav]

Thanks. I'll try that out.

Edit: That seems to have worked. Woohoo! Thanks a lot!