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Although the prototype was designed for 8 ohms, the amplifier can also work with a 4-ohm load. This will test the ThermalTrak's ability to control bias and prevent thermal runaway. Thanks.

The versions with a 'DG' suffix are still current (OnSemi, etc) and available (DigiKey, etc), eg NJL1302DG and NJL3281DG

@kiltrash1 mfg discontinued

FYI, you can still buy them at Mouser. Thanks.

FYI, if you go to Onsemi's website, these are listed as "active" devices: NJL3281D/NJL1302D -Pd 200W, and NJL0281/NJL0302D -Pd 180W version. Thanks.

@@buildaudioamps Nice that they started mfg it again. Thanks

Thank you too for watching.

Thank you! Cheers!

Please refer to the schematic diagram. Test results showed otherwise. Thanks.

Totalmente de acuerdo; es un circuito elevador de tensión que, usa señal de conmutación y produce ruido ; se deben usar una power supply convencional con transformador separador, estabilitzador y filtros bobinados o bancos de baterias de 1,5V en serie, hasta obtener los 32V de trabajo. Piensenlo!

for maximalist LT3042, preregulation LM317

@@joancarlescanadas5123 My reference power amplifier is an Icepower 1000ASP, shop.icepoweraudio.com/wp-content/uploads/2023/02/ICEpower1000ASP_Datasheet_1_7.pdf. It does not have a transformer, but is an audiophile professional high quality power amplifier. Thanks.

Thanks

Thank you!

Thanks. BOM is always available free by email request at support@buildaudioamps.com

Ok, thanks.

I'm using an adjustable DC-DC high voltage boost module. You can adjust the input voltage from 8-32VDC to an output of ±45-390VDC. Maximum output current is 200 mA and idles at 15 mA. Thank you.

support@buildaudioamps.com

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.

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

@@joancarlescanadas5123 That is correct. Thanks.

@@buildaudioamps Thank you!👍👍👍👍

Thanks.

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.

@@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.

@@InTimeTraveller Thank you.

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

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.

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.

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

@@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.

Thank you for your comment.

Addendum: the 0.03µF capacitor normally has 0.033µF😉

@@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😉

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.

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?

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

Sorry about that; I don't sell boards. Check this out on the website buildaudioamps.com/make-pcbs/

Thanks.

Thank you for your comment. BAA has built and tested 7 RIAA MM cartridge phono preamps, which will be published on this channel as part of a presentation video series on MM cartridge phono preamps. So far, 5 preamps have already been posted and 2 more to go. The RIAA preamp project prototypes are built with active components, namely, vacuum tubes, opamps and discrete transistors. The listening test of all 7 preamps is subjective in nature; using different vinyl record albums, input and output sources, each one has different musical/tone character. Because of this, the task of determining which one is best is both challenging and intriguing. The bottom line is that the presentation video about this series is not a review but as an educational resource for DIYers to build their own phono preamp.

Thanks. Please go to buildaudioamps.com/project-59/ for details.

Thank you. Sometimes your wish may come true. But I'll "try" to be as full time DIYer as I can be and enjoy building audio electronics projects and share to you. It is always said "If I can do it, you can too."

Thanks! The PCB layout in PDF is available free by request at support@buildaudioamps.com.

The same reason some people thing that vinyl is better then CD when it come to sound quality. It isn't.

Thanks. The next RIAA-equalized MM phono preamps following this project are two Opamp-based preamps and then another classic 16-transistor-based preamp to conclude the series.

@@davidlong1786 Thanks.

Good OpAmps are ridiculously expensive. A discrete Preamp with the same Quality is way cheaper to build. And more fun, too.

@@albinklein7680 Not true. Every plain vanilla 5532 outperforms such a transistor grave. And if I first have to measure the right transistors out of 100, it's not any cheaper.

Good catch! Sorry for the error in the schematic, but the part placement guide is correct if you have requested the plans. Thanks.

@@buildaudioamps Looking at the schematic, it looks like the bases of the input transistors will be sitting at around +0.6VDC, so therefore shouldn't C1 face the other way as well? Or do the bases sit at zero, the emitters at about -0.6V, and the output as well?

@@ScottGrammer Those are Nichicon Mfr # UES1H100MPM Bi-Polar/Non-Polar Electrolytic Capacitors Type: Bi-Polarized for Audio Equipment. Thanks!

Sorry I don't sell circuit boards; you have to make it yourself. If you need the PCB layout, send an email request to support@buildaudioamps.com. Thanks!

Correct. The project's enclosure is made of plastic, so the copper tape is connected to the preamp's ground by soldering a piece of hookup wire to it, which helps in reducing noise issues.

Thank you. FYI, I have finished another PCB prototype of a discrete RIAA-equalized phono preamp using 16 transistors for a 2-channel system. I will eventually publish it here soon on this channel, after two more RIAA-equalized opamp phono preamps are posted to complete the series!

Yes, in close proximity to the power output transistors.

Thanks

Thanks

What does “faster” mean in this context? Normally that would imply flatter response at high frequencies but, I doubt that you’ve made the measurements to support that claim. If you’re saying it sounds “faster” (whatever that means) can you then show the results of your double blind test setup with the results? Unsubstantiated opinions are no substitute for measurements or blind testing.

@@Obsfucation In the data sheet of good capacitors, the edge steepness is given in V/µS. WIMA MKP 10 is still rather "slow" with less than 1000V/µS (depending on the voltage resistance and size), WIMA FKP2 (33nF max) has 1000V/µS, WIMA FKP1 up to 29000V/µS. FKP1 as "affordable" goes up to 0.22µF (11000V/µS).

@@TTVEaGMXde Here's a topic about capacitors in audio applications: www.ti.com/lit/an/slyt796a/slyt796a.pdf?ts=1726532721186&ref_url=https%253A%252F%252Fduckduckgo.com%252F#:~:text=In%20many%20audio%20applications%20such,still%20available%20in%20small%20packages.

Capacitors do not have a property which can be described as "fast". Film capacitors do have limits on allowed dV/dT in V/µs, however in audio preamps, with only low voltages, this is absolutely never an issue, also not for the WIMA MKS capacitors. So the MKS series is an excellent choice for this application. However, the described circuit is useless without a partslist. Furthermore, the frequency response is far from the desired RIAA curve. So save yourself the trouble of building this thing...

It depends on the design. But wait for the next project, which will use 8 transistors per channel. Thanks.

@@buildaudioamps ok thank you sir

Circuit 29-16 in the RCA Tube Manual RC-30, pp. 702-703