I have finished PCB assembly. For servo op-amp, which one to use, OPA134 or LF411 or evenTL071?
Whatever meets the specs with the lowest dc offset and drift. Opa134 is good, 627 notionally measures better. Never heard a difference and I've built with many.
The effect of the servo will be drowned Ousby leakage from the big caps until they are fully formed. 50 hours of use and dc drift all but dissappears, until then output will swing 50 mV dc.
The effect of the servo will be drowned Ousby leakage from the big caps until they are fully formed. 50 hours of use and dc drift all but dissappears, until then output will swing 50 mV dc.
My Paradise phono is hum free and quiet , but sound is somehow soft and thick, not crisp enough.Input bias is adjusted. El. caps 6800 micro are rated at 16V. Not enough voltage(0.68V) to reform them in circuit?Should I have to replace them with 6.3V , and reform before soldering in circuit? Servo op-amp is OPA872.
Kamis, it usually takes about 50 hours for the caps to form, maybe a bit longer in your case. Until that time DC offset will not settle and your Paradise will sound 'veiled'.
When the caps fully form, Dc offset should disappear and everything firms ups, thins out and gets faster and more dynamic sounding.
Are you using Calvin's output boards?
Which power supply boards are you using?
What's the input voltage to your Paradise?
Which cart are you using, what cart loading have you applied?
OPA 872?
When the caps fully form, Dc offset should disappear and everything firms ups, thins out and gets faster and more dynamic sounding.
Are you using Calvin's output boards?
Which power supply boards are you using?
What's the input voltage to your Paradise?
Which cart are you using, what cart loading have you applied?
OPA 872?
I cleaned very dirty DC connectors,XLR 3 pins both plugs and sockets. Difference is huge, sound is now more open , much firmer and sharper . I solved problem! Now, I find sound is really up to Paradise reputation. DC connectors should be clean.I do not use alternate buffer. I power Paradise with Jung /Didden SR. Raw power supply is John Curl style with CM chokes on DC side. I load my Benz Micro Gold with 10K resistor,it is 5K total. Gold output voltage is 0.56 at 5cm/sec.
Paradise has zero hum and lower noise than Pass Xono.I do not measure DC offset anymore.Grounding tonearm has no influence on hum.Servo op-amp is OPA827.
I also use XLR's on my Paradise (Neutric silver plate) how did you clean the sockets ?
I have noticed some of the silver starting to oxidise.
I also have a thought about using such large connectors for 0.25mV.
I'm considering DIN plugs, or mini XLR.
or ?
I usually use Kontakt60 contact cleaner by Kontakt Chemie. Kitchen paper rounded on toothpick is the best applicator.
Thank you, it is really an outstanding , almost best possible overload margin.I noticed that records ticks and pops are handled well.If I remember correctly - overload margin should be 35dB
(0.5mV, with 65dB gain at 1kHz, and Paradise will easily swing +/-16V, when I do the math I get to 35dB)
good enough as far as I'm concerned......
If I remember correctly - overload margin should be 35dB
(0.5mV, with 65dB gain at 1kHz, and Paradise will easily swing +/-16V, when I do the math I get to 35dB)
good enough as far as I'm concerned......
I have forgotten to ask: what is a Paradise natural input capacitance?
0.5mVac with 65dB of gain and a 35dB margin for overload gives a maximum output of 50Vac with acceptable distortion. That would need ~150V supply rail, or +-75Vdc dual polarity supply.If I remember correctly - overload margin should be 35dB
(0.5mV, with 65dB gain at 1kHz, and Paradise will easily swing +/-16V, when I do the math I get to 35dB)
good enough as far as I'm concerned......
A +-16Vdc supply gives at best a maximum output of ~10vac. That is an overload margin of ~21.5dB
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