I see you use spectraplus. I used to use it over 10 years ago with my emu card and m-audio pro fire. Drove me insane how level dependent it is he good for quick checks.
Let me understand your graphs say 0.3V but you have 0.5V instead? So you feed it with 5mV. In that case you are in the noise region both generator and phono, you might want to see the THD+N instead to get a better idea. However since I assume 40dB is MC front end which will need an MM following section why not splitting the time constants passive/active instead to gain better headroom and accuracy?
Can you measure noise with spectra plus?! If not you can do FFT and then divide by square frequency and the correction factor for the filtering you use. Inout Noise figure is a very important measurement.
Let me understand your graphs say 0.3V but you have 0.5V instead? So you feed it with 5mV. In that case you are in the noise region both generator and phono, you might want to see the THD+N instead to get a better idea. However since I assume 40dB is MC front end which will need an MM following section why not splitting the time constants passive/active instead to gain better headroom and accuracy?
Can you measure noise with spectra plus?! If not you can do FFT and then divide by square frequency and the correction factor for the filtering you use. Inout Noise figure is a very important measurement.
This is another project that has not to do with this thread's builds and its confusing the topic. Please open its own thread and we will move the relative posts there.
No miracles can be expected from this simple circuit with few parts.
The idea of this circuit is to further develop the basic idea of (Simplistic NJFET RIAA) by making it able to work with very low power supplies without changing the essence of the idea!
The idea was simply to be battery powered.
I haven't had the board for a long time, so I can't take new measurements.
The idea of this circuit is to further develop the basic idea of (Simplistic NJFET RIAA) by making it able to work with very low power supplies without changing the essence of the idea!
The idea was simply to be battery powered.
I haven't had the board for a long time, so I can't take new measurements.
What I proposed is just a slight modification of the scheme discussed in the thread, and I don't see what more can be said about the slight modification so proposed, that it should be in a different thread.
The Simplistic NJFET RIAA concept has been deliberately preserved completely and only the load resistors have been replaced by dynamic loads (current generators).
But as you decide, anyway.
The Simplistic NJFET RIAA concept has been deliberately preserved completely and only the load resistors have been replaced by dynamic loads (current generators).
But as you decide, anyway.
Hello
is the wattage of the resistors crucial at R20 position? Just realised that the ones I have are 0.1 instead of 0.5W?
Thanks.
is the wattage of the resistors crucial at R20 position? Just realised that the ones I have are 0.1 instead of 0.5W?
Thanks.
There is no need for high power resistors anywhere in the circuit.
It's just that the board is made for metal-film 0.6W/0.25W
Without a problem, all positions can be 0.1W
It's just that the board is made for metal-film 0.6W/0.25W
Without a problem, all positions can be 0.1W
Not sure how to use the 10 W resistor - across the DC terminal and then measure voltage? Do not have these resistors - is there an alternative?
Yes, across the raw dc board's output terminal. And then measure DCV.
Just informing there is also an active test load alternative. Basic like a programmable CCS gadget or in professional format.
Practically, get simple power resistors to test, else there's the precarious scenario of utilizing the phono as a first test load.
Generally for protecting against hard failures there is always the old proven dim bulb tester (limiter) which is good to have.
Just informing there is also an active test load alternative. Basic like a programmable CCS gadget or in professional format.
Practically, get simple power resistors to test, else there's the precarious scenario of utilizing the phono as a first test load.
Generally for protecting against hard failures there is always the old proven dim bulb tester (limiter) which is good to have.
Without the PSU connected 37.4 VAC (2 transformers with 32 V secondaries), with PSU connected 50.1 VDC.
How do have to modify the PSU as voltage the exceeds 48VDC?
How do have to modify the PSU as voltage the exceeds 48VDC?
Install 27R 2W-5W RD/Link position resistors on the Raw PSU PCB. They will cut enough raw DC voltage when the outputs will be loaded with the actual phono channels.
27R RD/Link resistors add twenty seven Ohm before the 4700uF smoothing capacitors. Creating an RC HF filter and dropping few Volt upon load consumption. Depends on the transformer too. Each phono shunt regulator pulls about 100mA constant current on its standard setting.
The 1R and 27R resistor at that position are in series rather than parallel - or only the 27R is needed at this position and the 1R needs to be removed?
Today I bought Toshin UTJH audio grade expensive caps at local shop.
The leg is not magnetic.
100uf50v was too expensive (3.5usd)
So I bought 47uf50v(2usd)
Just for fun.
Before I tried 100uf16v on dac but I choose nichicon KZ.
Panasonic FC 100r is good, detailed sound.
Nichicon KZ 100r have more bass but sound overflowing and losing detail.
This time for Njfet RIAA,Toshin UTJH won.
It had detail and more colour in good way.
I want to try audio note kaisei cap if I have chance to buy.
I also have good results for adding 10R on regulator R1 5.6R.
The leg is not magnetic.
100uf50v was too expensive (3.5usd)
So I bought 47uf50v(2usd)
Just for fun.
Before I tried 100uf16v on dac but I choose nichicon KZ.
Panasonic FC 100r is good, detailed sound.
Nichicon KZ 100r have more bass but sound overflowing and losing detail.
This time for Njfet RIAA,Toshin UTJH won.
It had detail and more colour in good way.
I want to try audio note kaisei cap if I have chance to buy.
I also have good results for adding 10R on regulator R1 5.6R.
Attachments
Found a pair of 25 ohms 3 watts 1 % resistors in my stash. Any prediction possible if these are suitable / will provide enough resistance? If not I rather wait for the 27R to avoid rework.
Hi tamra
thank you for the interesting experiment.
It seems you are able to easily swap the caps - do you use sockets?
Which caps did you swap (C5 - C9?)?