Build an Inverse RIAA Network to Test Phono Inputs With a Signal Generator

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Only $5 for 10 PCBs and every new member get $5 bonus. + Express 24 hour / 48 hour service on www.pcbway.com/ ➠ ➠ ➠ How do you test the phono input of an amp with a normal a signal generator? I recently had just such a need and ran into some difficulties, so I decided to build an Inverse RIAA Network. This simple passive circuit adapts both the signal amplitude and equalisation curve to satisfy the phono preamp input requirements. It works both for Moving Magnet (MM) and Moving Coil (MC) levels, and the PCB makes it really simple to implement.
Two really important sources of information used in the making of this video:
➠➠ sound-au.com/p80-Inverse-RIAA...
➠➠ www.ovationhifidelity.com/wp-...
If you wish to order your own PCBs from PCBWay, the link is below:
➠➠ www.pcbway.com/project/sharep...
I hope you enjoy the video.
Other Creators mentioned in this video:
@xraytonyb ➠➠ • Assembling an Inverse ...
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Опубликовано:

23 апр 2024

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Комментарии : 37

@xraytonyb 3 месяца назад

Thank you for the kind words, Manuel! I'm a big fan of your channel. I really like your implementation of the Inverse RIAA circuit. Really clean design. All the Best!!!

@electronicsoldandnew 3 месяца назад

Thanks Tony 👍

@radio-ged4626 3 месяца назад

Yes, I saw XRayTonyB's video on this. He really does do a deep dive into theory at times. I like his descriptions of different types of amplifier circuits. As a repair oriented guy I like to see theory of opps, it helps understanding how something works in order to understand why it isn't working anymore or even how you can improve on it.

@electronicsoldandnew 3 месяца назад

👍

@manuelp6785 3 месяца назад

One other way to do it is with a test record. You will have a few frequencies that are fed directly by the turntable. This is my method, but I admit it is a bit messy having a turntable on the bench. We can also have this pre-RIAA signal generated by a PC and fed via a DAC. However this still needs a little circuit for attenuation and impedance matching. Your option is still valid and thanks for sharing.

@electronicsoldandnew 3 месяца назад

👍 those test records (or tapes and cds) can be quite expensive 😊 My needs are really simple, so I’d like to keep it simple too.

@fotoralf 3 месяца назад

Thanks for the video, Manuel. Another use for this circuit would be using the phono input of an amp as an additional line input.

@electronicsoldandnew 3 месяца назад

Yes, that would also work. I don’t really like that too much as noise will definitely be introduced.

@BJcanal270 3 месяца назад

Thanks for sharing your knowledge

@electronicsoldandnew 3 месяца назад

Pleasure

@retro_tech 3 месяца назад

Really nice! This looks to be super handy. I might build it in the future. Would you connect the ground via the metal case then? It's really easy to get ground-related issues when connecting up a signal generator to a phono input causing all sorts of distortion.

@electronicsoldandnew 3 месяца назад

I would make the case ground, connected to the signal ground at one point only.

@mackfisher4487 3 месяца назад

Nice project for the audio file, XRayManel

@electronicsoldandnew 3 месяца назад

😊 XrayMacTipton? It’s an honour 😊

@HyyskanPolttaja 3 месяца назад

Just cover the inside of your 3D-printed box with copper-tape. The kind used to repel snails and stuff. That'll give you a shielded box. :)

@electronicsoldandnew 3 месяца назад

👍

@EJP286CRSKW 3 месяца назад

All that work, but let me tell you the easy way. Feed 1mV at 1kHz into the phono input. Set your dB reading meter to 0dB. Change the frequency to 20kHz. You should read -19.91dB. Change to 20Hz. You should read +19.91dB. Check that it isn't clipping at this frqequency: if it is, lower the level and start again. If these three points measure as above, the rest of the RIAA EQ curve has to be perfect, by definition. Typically you will read a little under at both extremes. EJP

@electronicsoldandnew 3 месяца назад

👍

@wolfgangrichter6088 3 месяца назад

Manuel, why didn't you add a DIN receptable which is used by your favorite German radios ? As a cruel punishment for not doing so, you have to find a tube radio with moving coil input now.

@electronicsoldandnew 3 месяца назад

😊 none of the radios I restore use riaa equalised phono inputs.

@jean-pierredesoza2340 3 месяца назад

Using my script, here is how it solves it with 3 résistances of the général E12 series : Using three of E12 series of resistance values in parallel to make 883.30Ω within 0.5 % precision, combine 1800Ω with 2200Ω and with 8200Ω giving 883.35Ω, with 0.0% tolerance combine 1200Ω with 5600Ω and with 8200Ω giving 881.95Ω, with 0.2% tolerance combine 1500Ω with 3900Ω and with 4700Ω giving 880.40Ω, with 0.3% tolerance combine 2200Ω with 2700Ω and with 3300Ω giving 886.57Ω, with 0.4% tolerance combine 1200Ω with 6800Ω and with 6800Ω giving 886.96Ω, with 0.4% tolerance

@electronicsoldandnew 3 месяца назад

👍

@Wildknaap 3 месяца назад

Why not use trimmer pots instead of resistors in series? Yes, it means you’ve to calibrate just before measuring. 😊

@electronicsoldandnew 3 месяца назад

I prefer the solution of setting it up once and it’s done.

@markswann5981 20 дней назад

Hi Manuel, thanks for sharing this project. I have just ordered some PCB's, would it be possible to get a copy of the files for the 3D printed box?

@electronicsoldandnew 20 дней назад

Sure. Email me and I’ll send you the files.

@daveturner5305 3 месяца назад

I would really like to have seen a Bode plot for this for completeness. Cheers.

@electronicsoldandnew 3 месяца назад

👍

@TheEmbeddedHobbyist 3 месяца назад

In electronics new, i would just write a bit of code to drive the osc output level to a value dependant on the frequency selected. Job done. Now i just got to build a mixer to get my RF programable osc to produce audio. 🙂

@electronicsoldandnew 3 месяца назад

👍