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Old 4th July 2011, 02:52 PM   #6591
Salas is offline Salas  Greece
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Quote:
Originally Posted by Joshua_G View Post
Would 1% accuracy to the RIAA equalization components eliminate the need for tweaking values? Or is it always up to a personal taste and adjustment to the preferred tone of the entire system?
The values I give in the PDF are looking good on the simulator and the FFT measurement, also seem to bring acceptable tone judging by anecdotal feedback in the course of the thread with its many builds. With 1% you got a known standard for this preamp. I don't warn against playing with the EQ non the less if someone wants to tune there than elsewhere. EQ is EQ nobody dies if to tamper with. We have done worse.
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Old 4th July 2011, 03:04 PM   #6592
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You can adjust the tone by tweaking the riaa filter values but that way you will go away from the perfect riaa curve.

To retain the REAL instruments timbre you should look for the 318uS correlation.

For a 48dB gain you should use 15.33nF on the trebble cap.
For a 57dB gain you can lower it to 15.1nF.

The main riaa filter resistor depends on the output impedance of the first stage and must be calculated for each build depending on the measured resistors values.
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Old 4th July 2011, 03:13 PM   #6593
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Be care for 1%, I bought 47nF 500V 1% SM and received one 46nF & the other 47nF (so one of them it's not accurate), each paid 19€39

Only option 1% 15nF & 47nF VISHAY-RODERSTEIN MKP-1837 Metalized Polypropylene Film Capacitor but who knows if it's really 1%
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Old 4th July 2011, 03:16 PM   #6594
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Originally Posted by RCruz View Post
You can adjust the tone by tweaking the riaa filter values but that way you will go away from the perfect riaa curve.

To retain the REAL instruments timbre you should look for the 318uS correlation.

For a 48dB gain you should use 15.33nF on the trebble cap.
For a 57dB gain you can lower it to 15.1nF.

The main riaa filter resistor depends on the output impedance of the first stage and must be calculated for each build depending on the measured resistors values.
I will try C3 with 15.1nF to see what's happen with highs.
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Old 4th July 2011, 03:19 PM   #6595
Salas is offline Salas  Greece
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Originally Posted by merlin el mago View Post
Only option 1% 15nF & 47nF VISHAY-RODERSTEIN MKP-1837 Metalized Polypropylene Film Capacitor but who knows if it's really 1%
It is. I have checked those many times. Polysterene honor their tolerance too. Big international manufacturers in general have the means.
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Old 4th July 2011, 05:08 PM   #6596
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RS, Farnell, Digikey & Mouser don't have 1% styrenes 16nF & 47nF
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Old 6th July 2011, 08:56 PM   #6597
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Originally Posted by merlin el mago View Post
I will try C3 with 15.1nF to see what's happen with highs.
I don't like 15.1nF for C3, I will try with 15.33nF.
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Old 7th July 2011, 10:02 PM   #6598
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It also depends on the type of cap you are using for the 15n..... And remenber it interacts with the shunt´s output and vref cap choice.... Output zobel is the major factor here when it comes to tone.... Vref deals with extension and control.

For example: 13nF Silver Mica // 2.3nF Styroflex is very different from 13nF SM // 2.3n silver mica.
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Last edited by RCruz; 7th July 2011 at 10:05 PM.
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Old 8th July 2011, 09:53 AM   #6599
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Thanks for advice Ricardo.
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Old 8th July 2011, 06:20 PM   #6600
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Send a message via MSN to sq225917
https://www.rush-on-line.co.uk/cap_index.php

they usually stock what I need. Awful slow service but great availability..
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