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Old 14th December 2011, 09:37 AM   #3551
FdW is offline FdW  Netherlands
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Originally Posted by MiiB View Post
Now were talking power-supply,,, the total consumption at 24V is app 100 mA each rail, so in total app 5W each channel
If the circuit consumes 100mA then I need to recalculate the power supply for a current source of 150mA. Can you tell me what the maximum consumption of one mono channel will be (I guess we go for full dual mono).
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Old 14th December 2011, 09:38 AM   #3552
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Also, I would like to know if the power supply should be designed for LED's or zener's.
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Old 14th December 2011, 09:46 AM   #3553
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A string of LED's is also possible. Use a selected resistor (trimmer) for R7. The more LED's the better; I would say a minimum of five.
These LED's (in the schema) are about 2Volts each (15Volts for the string of 8). The number of LED's also depends on the forward voltage of the LED. A total of, between, 20 and 22Volts will be ideal.
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Old 14th December 2011, 09:52 AM   #3554
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That is one mono-channel... 105 mA is drawn from each voltage source...
So we need 10 green lED's, a zener is app 20uV noise and an LED can be as low as 3-4uV, question is.. does that sum up or does is stay low due to the random spectra of the noise..??

Last edited by MiiB; 14th December 2011 at 09:58 AM.
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Old 14th December 2011, 10:28 AM   #3555
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If the diode's noise is a voltage source, than it has to add, no?

RŁdiger
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Old 14th December 2011, 10:56 AM   #3556
MiiB is offline MiiB  Denmark
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I can see I remember a bit Wrong on the values for noise, Here there is a nice piece of work regarding noise in LED and Zeners, Made by Swedish DIY-Audio forum member Christer (Majstang, Krebs og surstrÝmming)
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File Type: pdf noise_measurements_1_4.pdf (72.1 KB, 53 views)
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Old 14th December 2011, 11:17 AM   #3557
Salas is offline Salas  Greece
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Originally Posted by Onvinyl View Post
If the diode's noise is a voltage source, than it has to add, no?

RŁdiger

Non linearly though, because uncorrelated. You got to sum their squares and then sqrt that number.
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Old 14th December 2011, 11:19 AM   #3558
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Originally Posted by MiiB View Post
I can see I remember a bit Wrong on the values for noise, Here there is a nice piece of work regarding noise in LED and Zeners, Made by Swedish DIY-Audio forum member Christer (Majstang, Krebs og surstrÝmming)
Given that the zener's may be a bit inconsistent, you may still like to select LED's for the reference. Using a string of 12 Yellow LED's would (Vrms added) generate about 1.3uV down to 1uV (being very optimistic) of noise (according to the list). I would say, we make place for the string of LED's and the builder can always stuff an zener diode in their place.

Last edited by FdW; 14th December 2011 at 11:23 AM.
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Old 14th December 2011, 12:35 PM   #3559
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Frans, you are very pragmatic and i like that. Yes, we should make place for some Leds.
I personally have no problem with toroids either. I agree that the transformer should be in another compartment or in a separate box. This is the only way to avoid hum in a low lever circuit like that. Your preamp looks great inside. I like the copper pipes.
MiiB, that is what i was expecting. Gain goes up and so does distortion. -96dB is of cause excellent and the distortion distribution looks great. The only think i would like to see is when you go back from 50 Ohm degeneration to 20 Ohm and adjust the RIAA again for a gain of 61dB. If we get out the same distortion then the 20 Ohm degeneration would give somewhat less noise. I think after that experiment, we fix the parameters.
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Old 14th December 2011, 01:04 PM   #3560
FdW is offline FdW  Netherlands
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Frans, you are very pragmatic ...
Thanks and yes I think so

Here a version with the filter, snubber resistors and LED's. The current has now been set to 150mA ( 105mA for the amplifier, 45mA to warm the planet).
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File Type: jpg Shunt Vreg 24V using LEDs.JPG (455.4 KB, 215 views)
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