About the resistor values, it's part of a CRC filter designed to attenuate the high frequency noise generated by the LM7x12 voltage regulators. The larger it is the better it works as a filter, but the impedance of the power supply at low frequencies increases proportionally.
I think 10 ohms is a maximum value for the amount of resistance you want to put there, you might want to try less or none at all (jumper).
I think 10 ohms is a maximum value for the amount of resistance you want to put there, you might want to try less or none at all (jumper).
I thought about that, but I tried that idea long ago on a different RIAA preamp, and the result was quite awful. Perhaps the inductance (high Q tank circuit) interacts with the high feedback op amp IC adversely?
You are welcome to argue that LM7812 is sufficient, given surface noise of the record, parasitic noise coupling, op amp PSRR etc. etc. Indeed from a databook perspective the 3 terminal regulators don't seem bad at all**. I prefer the X-reg though, in direct listening comparison I found it far superior to LM7812 or LM317.
**The LM78xx series is quoted for 72 dB ripple rejection at 120 Hz and 50 microV noise for 10-100k bandwidth. I've just shown that the X-reg has a ripple rejection of 120 dB at 100 Hz. The noise floor is about the same, 50 microV (calculated), but the difference is that above 2 kHz the LM7812 drops below 60 dB ripple rejection. The X-reg (LTSpice simulation) still gives 120 dB ripple rejection at 10 kHz, and 107 dB at 100 kHz, where the LM7812 is down to 40 dB. Without compromising output impedance like a CRC filter would. So the difference here is easily demonstrated at least.
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A time limited post for the regular readers of this thread. The files will only be hosted for a few days.
Two wav. files. One is a VSPS 300. Another is something else, no hints.
File A
File B
Can you hear a difference? If so, which do you prefer and why.
No prizes, but you are allowed a degree of smug satisfaction if you guess right.
Two wav. files. One is a VSPS 300. Another is something else, no hints.
File A
File B
Can you hear a difference? If so, which do you prefer and why.
No prizes, but you are allowed a degree of smug satisfaction if you guess right.
ok i'll take a shot
file a is more open and better bass definition but more surface noise. nice and smooth i like
file b is a bit congested but less surface noise and week bass.
i would like to hear both files the same part of the song to make a better judgement.
but i'm listening on a crappy computer with old Altec Lansing 4.1
file a is more open and better bass definition but more surface noise. nice and smooth i like
file b is a bit congested but less surface noise and week bass.
i would like to hear both files the same part of the song to make a better judgement.
but i'm listening on a crappy computer with old Altec Lansing 4.1
Hi Richard,
Metallica isn't really my cup of tea. Gave it a listen with a BT headset connected to my notebook. I think ...if File A is the VSPS 300, File B might be the stereo VSPS or maybe the same song from CD.. They are different but can't say wich one I prefer. File A is clearly a record, File B lacks record noise, File A is more open and broader stereo, File B narrower but more forcefull.
Regards,
Ronald.
Metallica isn't really my cup of tea. Gave it a listen with a BT headset connected to my notebook. I think ...if File A is the VSPS 300, File B might be the stereo VSPS or maybe the same song from CD.
. They are different but can't say wich one I prefer. File A is clearly a record, File B lacks record noise, File A is more open and broader stereo, File B narrower but more forcefull.Regards,
Ronald.
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There was a glitch in the first file. That's no good, let me do it again.
Same order as before, but now both are the same section of music:
Test A
Test B
That should make it do-able at least. Sorry! (I wasn't out to make it any harder than it needs to be.)
I deleted the original uploads. Click the link, click to download. The .wav file ends up in your browsers default download directory. You can play it as many times as you like, wherever you like.
Same order as before, but now both are the same section of music:
Test A
Test B
That should make it do-able at least. Sorry! (I wasn't out to make it any harder than it needs to be.)
I deleted the original uploads. Click the link, click to download. The .wav file ends up in your browsers default download directory. You can play it as many times as you like, wherever you like.