Or, float the input and output sockets on the paradise, so signal gnd has no chassis bond. And run the chassis back to mains 0v via a DDRC.
If there's continuity between gyrodeck chassis and tonearm you don't need another gnd just that 3rd wire in the arm.
If there's continuity between gyrodeck chassis and tonearm you don't need another gnd just that 3rd wire in the arm.
I tried to search without success through all the threads. Is it possible to decrease the gain of this preamplifier? I use a cartridge with 0,5mV nominal and the output is still undistorted, but the value is quite high. I cannot use the whole range of the volume control of the next stage. Thanks in advance!
Thanks! I use the first schematic, I built the preamplifier in 2013, without the Calvin buffer
With this schematic you can not change the gain easily.
RIAA network is the load and determines gain.
RIAA network is the load and determines gain.
So let's say I want to reduce the gain by 3 times, I would then need to reduce the network impedance by 3, keeping the RxC product the same:
73.5kΩ will become 24.5kΩ; 9.1kΩ + 33.3nF will become 3.0kΩ + 11.1nF and 220Ω + 11nF will become 73Ω + 3.7nF
Is this approach correct or I am completely wrong?
73.5kΩ will become 24.5kΩ; 9.1kΩ + 33.3nF will become 3.0kΩ + 11.1nF and 220Ω + 11nF will become 73Ω + 3.7nF
Is this approach correct or I am completely wrong?
Yes, scale all values by a factor of three (this will be about 10 dB), but this means increasing the capacitances accordingly.
Yes, you are absolutely right, to preserve the time constants I need to increase the capacitors, not decrease them (my bad)
So
So
- branch 2: to keep 9.1k⋅33.3n=3.03k⋅C ⇒ C=100nF
- branch 3: 220⋅11n=73.3⋅C ⇒ C=33nF
I should try these values