RIAA Response question

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Hello. I have a question. I have built a phono preamp based on Solidphono of TNT. In principle values ​​of resistors and capacitors in the RIAA network without having measured, ie their usual variations, I found a good preamp.
But I gained a multimeter that is capable of measuring resistors to range from 0.1 ohms and 30 pF capacitors.
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From this, I used the calculator Kabusa RIAA, and from the resistor R1
I figured the other component values.
I have taken the values ​​of resistors up to 99.5% and 99.9% of the calculated and capacitors to 99.40% and 100% of the calculated value (values ​​using serial and parallel).
Metal film resistors and capacitors are polypropylene.
The RIAA network is passive and is used as one SSM2019 first amplifier stage and last stage as OP275.
Result, the sound has changed. It is more natural, prone to the warmth; voices seem more natural and clear; agudor present clear, with details not heard before, not strenuous; the soundstage has improved adding depth. The dynamic is good but not changed by adjusting the RIAA network.
If I compare with P06 Elliott is warmer than this but without losing detail.
QUESTION: It got better subjectively the ear, but the real answer will RIAA ?. I have no way to measure nu calculate with software. That's why I ask someone on the forum, if you have a software where you enter values ​​of capacitors and resistors and see the graph of response, few dB away or approaches RIAA.

An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.


Where is the little hand I put a resistor of 2k2
 
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Thank you for your contribution Rayma, but tended to buy an inverter RIAA. Accurately build me not be possible.
Calvin, I could not correctly interpret the file you have sent me.
Is a software where data is entered and delivers what response is obtained RIAA ?. Like I appreciate, but do not open it or use it.
I just wanted to know that deviation of the curve has the preamp I've built. It sounds great, but that does not mean that the curve quire is correct. I read somewhere that should be close to + - 0.2 dB.
Regards.
 
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You can open Calvin's file if you download and install the free LTspice simulator. Then you can directly read off the actual RIAA for your components.

It takes some effort to get going but will pay for itself.

As to RIAA correction: the frequency response of your cartridge will be much more variable than any RIAA correction, so the cartridge you have has much more influence. If you are happy with your values, than that's fine. It may not follow exactly the RIAA but it may be flat in combination with your cartridge...

Jan
 
Ok. I will build a RIAA investor and will install the software they told me, and see that this has left me preamplifier. They say it is based on Lehmann Black Cube. As for what they tell me there are so many variables to the response of a phono preamp, I can not believe so. If it really is as random the resulting sound, never spend money buying eg one Lehaman (USD 1000- 1500) since the sound depends on many other factors.
 
Hello. I used the simulator to suggest me Calvin.
I have entered the values of resistors and capacitors I calculated KAB and I have achieved almost 100% of that value using series and parallel.
They think of the RIAA response has been achieved?
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Then I will look for the difference with the actual curve.
I still do the RIAA investor who suggested me Rayma and see results.
Regards.
 
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IMO, with inexpensive equipment you can build a more accurate inverse RIAA circit than you can directly measure RIAA response. Because of the large dynamic range and frequency span, the direct measurement is harder to do accurately than most realize. With the inverse filter you can also look at square wave response, which makes errors stand out like a sore thumb.
 
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Joined 2011
you have small errors in inverse circuit and in DUT accumulated no?

Sure, all experiments have various error sources, that's part of science. But, you can estimate the errors from each source, add them,
and estimate the worst case error. Ideally that should be significantly less than your desired spec. (For large numbers of circuits
you would use a more statistical method, but your particular parts may not be close to the average.) I hand select all
my RIAA parts to 0.1% or better, and then make matched pairs of each for good tracking between channels.
 
IMO, with inexpensive equipment you can build a more accurate inverse RIAA circuit than you can directly measure
RIAA response. With the inverse filter you can also look at square wave response, which makes errors stand out like a sore thumb.

I've also found that this method works well. Just select your inverse RIAA parts carefully for a close tolerance.
 
I am currently implementing a RIAA deemphasis EQ preset in rePhase, but the data I have is not reliable enough.
Could you please export this curve as a 3-column file (frequency, magnitude, phase) with a high frequency range (say 1Hz-100kHz) and high resolution?

I did a minimum phase RIAA (5440 coefficients @96K) for my article in the next Linear Audio, ~.00001dB and .00002 degree even at 20Hz without using any windowing.
 
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Hi,

here´s the inverting Riaa schematic I use.
It has the Neumann EQ included and features three switches per channel to switch between MM(-40dB) and MC(-60dB) and between four source impedance values (0R, 50R, 550R and 600R).
I used serial and parallel connected parts to reduce tolerances.
Resistors are Metal film 0207-size and Caps are Mica, 1%, all sourced from Reichelt.de.
The PCB is housed in a small HF-aluminum casing.
Just feed the input connectors with a signal from a signal generator, or CD-Player and connect the output to Your phono-stage input.
Besides control listening, You can check amplitude- and square wave response.

jauu
Calvin

btw. the asc I attached earlier has the anti-Riaa implemented.
Just use that one for Your own sims to see deviations from the ideal linear response.
 

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