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 24th December 2010, 06:35 PM #5501 diyAudio Member   Join Date: Apr 2003 Location: Southern Tier NY It will be Merry Christmas with the Simplistic Playing. Merry Christmas to all. __________________ Living Life Doing the Waltz in 4/4 meter.
nhinstruments
diyAudio Member

Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Quote:
 Originally Posted by massimo Generally speaking, the smaller (your system can support), the better. Salas is absolutely right. Check the input impedance of the following component and calculate the right value for 10 - 15 Hz. As we are dealing with a less than perfect source, even if you cut a bit of low frequencies, is not that bad. Think about all the problem related to the warp of records and/or plinth resonance.
I am preparing a salas riaa for a friend that uses seriously undamped speakers and in my first approach we noticed that the bass cones move wildly when there is not music playing (when the needle is on the cueing part of the disc).

My initial build has 6,8uF on the output and I guess even 4,7u is too much.

Following massimo´s idea I should xcalculate a -3dB rolloff at 10-15Hz.

Pelase inform if my calculations are right:
using the following formulae: C = 159155 / (R x F)
"The 'magic number' 159155 is derived from 1000000 / (2 * pi)"

Amp input impedance = 20k ohm
Rolloff freq = 10Hz
Cout should be 0.8uF

diyAudio Chief Moderator

Join Date: Oct 2002
Location: Athens-Greece
That's what it'll do.
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 25th December 2010, 04:27 PM #5504 diyAudio Member   Join Date: Dec 2002 Location: Milan, Italy Riaa stage with subsonic filter.... embedded! Cute. Only DIY can taylor a component to the system needs. P.S. you should calculate Salas o/p imp//following amp i/p imp in your formula
nhinstruments
diyAudio Member

Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Quote:
 Originally Posted by massimo P.S. you should calculate Salas o/p imp//following amp i/p imp in your formula

 25th December 2010, 05:14 PM #5506 diyAudio Chief Moderator     Join Date: Oct 2002 Location: Athens-Greece Output impedance is only around 30 Ohm, will not change something much.
nhinstruments
diyAudio Member

Join Date: Sep 2006
Location: Wallis
Blog Entries: 1
Quote:
 Originally Posted by Salas Output impedance is only around 30 Ohm, will not change something much.
Just for learning purposes.... can you post the correct formulae ?

 25th December 2010, 05:52 PM #5508 diyAudio Chief Moderator     Join Date: Oct 2002 Location: Athens-Greece There is nothing more than the known first order CR high pass filter formula. Its if there is significant output impedance it forms a time constant with the capacitor that makes it appear bigger. In this case there is a buffer and the effect is negligible. Calc.
diyAudio Member

Join Date: Apr 2003
Location: Southern Tier NY
Merry Christmas!!!!!

I like this time of year as I get a little down time from work and can focus. Starting to complete a few of the project lists I have for the simplistic.
Attached are photo's of the new power supply and V1.2R for my simplistic. After a brief break to play with some of my kids gifts, I am going to breadboard it and fire it up.
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__________________
Living Life Doing the Waltz in 4/4 meter.

 25th December 2010, 06:51 PM #5510 diyAudio Chief Moderator     Join Date: Oct 2002 Location: Athens-Greece Merry Xmas 2U2. Let us know how it went later.

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