Build this OPA37 Ultra-Low Noise RIAA Phono Stereo Preamplifier.

[@TTVEaGMXde]

Instead of the no longer available transistors in the operating voltage denoiser, I would use TOSHIBA TTC004B (NPN) and TTA004B (PNP) with hFE 200 type. As electrolytic capacitors in the voltage denoiser I would use 6x 25V1000µF low ESR. In 1984, the OP37 was the first "high-end" OP-Amp. Today, however, it has already been overtaken by the LM4562 (Dual). Instead of the 30nF you could have just drawn in 2x 15nF capacitors. All my Opinion😉

[@buildaudioamps]

Thank you for your comment.

[@TTVEaGMXde]

Addendum: the 0.03µF capacitor normally has 0.033µF😉

[@TTVEaGMXde]

@@jim9930 As an input Op Amp, I would probably prefer the OPA1611, as it has a low "bass" noise increase and little difference between voltage noise (MCH/MM) and current noise (MCL). That is why it seems ideal for an MCM (1.5mV) amplifier. I developed a low drop fixed voltage regulator with only 3 transistors myself. RECOM now offers the very inexpensive REC10K-4824SAW/H2 10W 24V DC/DC Converter. All my Opinion😉

[@ScottGrammer]

Nice. I think I'd use a slightly bigger box and power it from four 9V batteries. That's how my current preamp is powered. I bypass the batteries with 100uF electrolytic and 1uF film caps, and voila, no power supply noise. I built mine with an NOS Signetics NE5532, and it gets about six months of use out of a set of four alkaline batteries. I replace them when they get down to 5V apiece. I wonder what the improvement would be in moving from the NE5532 to this opamp?

[@buildaudioamps]

Thank you for your comment. Smart! However, when converting your project using the OPA37, be sure to check the datasheet first for the correct pinouts of the chip. OPA37 is a single-packaged Opamp, while the popular NE5532 is dual-packaged.

[@jedi-mic]

I was going to ask the same question about running on 9 volt batteries have you tried running it off AC to DC transformer? What about lithium battery?

[@buildaudioamps]

@@jedi-mic Sorry, If I may answer, I'd prefer lithium-ion cells because it will last longer.

[@joancarlescanadas5123]

Hello, I liked your video. I understand that the values ​​of the circuit components are those shown in figure 7, but what values ​​do RL and CL have, those at the input of the preamp? Thanks.

[@buildaudioamps]

Those are the recommended load impedance and capacitance from the MM cartridge manufacturer. The AT-VM95C/H that I use, Audio Technica recommends Rl at 47K and Rc from 100 pF to 200 pF. Those values will depend on what MM cartridge you are using.

[@joancarlescanadas5123]

@@buildaudioamps Thanks, I use a ATVM95E (Audiotechnica) capsule. I suppose that the CL value, between 100pf and 200pf may be appropriate!

[@buildaudioamps]

@@joancarlescanadas5123 That is correct. Thanks.

[@joancarlescanadas5123]

@@buildaudioamps Thank you!👍👍👍👍

[@InTimeTraveller]

I would suggest using at least a two layer board and a solid copper ground plane. You're not gonna achieve low noise operation otherwise. Your design currently from a layout perspective is extremely sensitive to EMI noise. And perhaps also SMD components so that you can minimise the feedback loop as much as possible (in order to have even less total surface area susceptible to external magnetic fields).

[@buildaudioamps]

Thank you, and your suggestion is exactly the best method to create a better PCB layout. However, for a single home-built prototype, it's just impractical. I understand that the prototype has its limits, but the bottom line is that I must share with you and others my music listening experience with it. Listening to various old recordings of vinyl LPs, continues to amuse me with the sound quality it reproduces. It's a simple design that required little effort to build.

[@InTimeTraveller]

@@buildaudioamps it's really not impractical, even if you want to etch the board yourself (which I don't know why you would but fine), you can get a two layer board and use the top side for signal and the bottom side for ground. You can also order it from companies like PCBWay, JLCPCB, etc. A solid ground plane is a must if you're doing any kind of sensitive analog project.

[@buildaudioamps]

@@InTimeTraveller Thank you.

[@jedi-mic]

What is the total noise floor? you showed the noise floor of the opamp only what is the actual noise floor with the circuitry?

[@buildaudioamps]

The entire prototype is being tested by the audio analyzer, so that's the overall raw test result for THD, THD+N and SNR in stereo.

[@y_x2]

Are you using low-noise resistors also?

[@buildaudioamps]

All resistors are 1% metal film, purchased from a reputable authorized parts online dealer close to home in Texas. Thanks.

[@poormanselectronicsbench2021]

@ 4:23 How is that anything close to an RIAA equalization curve? You should be at a zero point at 1K, +20db @ 20 Hz, and -20db @ 20K. The amp performance itself looks good, but that RIAA not so much. I know you are using a linear versus logarithmic frequency scale, but still, that plot shows dropping 30db just from 20 to about 300Hz, and instead of a further roll off over 17K, it starts to pass a higher level over that point.

[@buildaudioamps]

The project was built according to the schematic diagram on Figure 7 of the Burr-Brown's OPA37 application note SBOS135C. The given RIAA network component values were left unchanged from their original design. I apologize, but the audio analyzer's frequency response test produced that result. Subjectively, the music listening test is satisfactory or excellent while using several MM cartridges on different vinyl LPs. Thank you.

[@yeoldestuff]

It looks like this because the scale is incorrect, the X axis should use the logarithmic scale. Minor deviations could be caused by loose component tolerances

[@buildaudioamps]

@@yeoldestuff There is no lin/log option when you run an FR test on the UUT. QuantAsylum's QA400 will output a sweep AF range and displays the result endlessly. All resistors in the prototype are using 1% metal film and affordable 10% film capacitors. Brown-Burr calculated the RIAA network values for us to build, as is. Thanks.

[@Photonicpainter]

I looked your graph of harmonics,actually I will reccomend to use it with battery power supply.If you will see you have on graph relatively strong 2-3 harmoniscs from 50 hz /around -75-80db).Use it with battery power supply and they will be gone.IMHO.

[@buildaudioamps]

Thanks.