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Old 27th March 2013, 06:59 AM   #2321
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I was to curious to find out. Generated a test tone with Rightmark Audio Analyser - applied an inverse RIAA-curve in Audacity - played that sample back through the Edirol and recorded the signal back again. Then analysed it using Rightmark. I believe this is what you wanted, RJM?

Click the image to open in full size.

20Hz to 20kHz +-0.5dB
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Old 27th March 2013, 09:29 AM   #2322
JBdV is offline JBdV  Netherlands
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Nice!
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Old 27th March 2013, 11:01 AM   #2323
rjm is offline rjm  Japan
Richard Murdey
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Quote:
Originally Posted by vulejov View Post
OK, same simulation..
I think your problem is you don't have fine enough sampling.

Try trans 100m 90m and 1u and see what that gives you. This moves the sampling window out to 90 ms from start up (to reach steady state, just in case) and samples 10 ms at 0.0001 ms steps, for 100 000 data points and 10 complete waveforms. Overkill, probably. Increase the step size until you see artifact peaks show up. That gives you your working limit.
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Old 27th March 2013, 11:05 AM   #2324
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Quote:
Originally Posted by Wirehead.be View Post
20Hz to 20kHz +-0.5dB
Ok, you win this round! I see you even managed to correctly reproduce the little tip up at 20 kHz from the 4th time constant...

To achieve such stellar results, did you measure/match the RIAA caps, or were they the standard kit ones?
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Old 27th March 2013, 11:07 AM   #2325
vulejov is offline vulejov  Serbia
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OK, but what about equation for RIAA?
What are values R1, R2, C1 and C2, how to add C2 to R2?
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Old 27th March 2013, 11:33 AM   #2326
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Quote:
Originally Posted by rjm View Post
Ok, you win this round! I see you even managed to correctly reproduce the little tip up at 20 kHz from the 4th time constant...

To achieve such stellar results, did you measure/match the RIAA caps, or were they the standard kit ones?
Oh, not about winning - I just love it that DIY-projects can give you great results at a fraction of expensive equipment.

The RIAA caps were not matched, I do not have a capacitance meter. They are Wima FKP2 caps (all of them). All of them 1nF, C2 made of 3 in parallel. The resistors are metal film, matched. Output cap is Wima MKP-X2 - 2,2uF. For the rest, I kept the PCB as small as possible and kept to your construction guide (star ground,...)
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Old 28th March 2013, 12:03 PM   #2327
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"What are values R1, R2, C1 and C2, how to add C2 to R2?"

The Phonoclone RIAA network is expressed as 750k || 110k + 3 nF || 1 nF for
R1 || R2 +C2 || C1. Careful, I may not have been consistent in the parts labeling in the sims.

C2 and R2 add as R2 + 1/(2 pi f C2)i. i is standard notation for an imaginary number, indicating that the reactive term is 90 degrees out of phase from the resistive term.

Suggest you do some reading. "The Art of Electronics" by Horowitz and Hill is my go-to reference.
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Last edited by rjm; 28th March 2013 at 12:06 PM.
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Old 28th March 2013, 06:50 PM   #2328
vulejov is offline vulejov  Serbia
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Quote:
Originally Posted by rjm View Post
Perhaps you are thinking of the conventional RIAA network where the resistor and capacitor are connected as (R1||C1)+(R2||C2) and R1~10xR2. (see the input inverse-RIAA I'm using in the sims below for an example) In the VSPS/Phonoclone it is R1||C1||(R2+C2). The ratio of the resistance values are different.
Quote:
Originally Posted by rjm View Post
The Phonoclone RIAA network is expressed as 750k || 110k + 3 nF || 1 nF for
R1 || R2 +C2 || C1. Careful, I may not have been consistent in the parts labeling in the sims.
I'm afraid I can not keep track..
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Old 30th March 2013, 09:40 AM   #2329
vulejov is offline vulejov  Serbia
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Quote:
Originally Posted by rjm View Post
Suggest you do some reading. "The Art of Electronics" by Horowitz and Hill is my go-to reference.
There is practically just one paragraph and nothing else about the RIAA..
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Old 30th March 2013, 11:18 PM   #2330
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Did some further measurements in Rightmark - full results are here.

As seen earlier - frequency response is dead-on like the simulation on rjm's page (seen here):
Click the image to open in full size.

Noise level is nice and quiet too:
Click the image to open in full size.
Note that is not an X-Reg version like rjm ships them, this should be even better for his. I'm using an LM317/LM337 combo, using the additional ripple caps on the adjust pin (10uF). 4400uF on each rail before the regulator. 1uF tantal to decouple (like the original National specs say). Each rail has a led indicator to make sure the minimum current draw is reached.
I think this could still be improved by a CRC-style filter feeding the regs (note the small "bump" at 50Hz). Still, dynamic range is at +83.0dB A-weighted, which is already more than what vinyl as a physical media might give you
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