My phono preamp for MC cartridges, His Master’s Noise, was published as a feature article on diyAudio.com. Check it out there! I discuss overall system design, noise calculations, design for low noise, and present a circuit with excellent linearity, high overload margins, good conformance to RIAA equalization, high power supply immunity, and high stability.
Soon to come, a moving magnet preamp using the same balanced-in-unbalanced-out approach as His Master’s Noise.
I would love to get a better idea of your “soon to come moving magnet balanced to unbalanced phono preamp”. What a beautiful acronym: STCMMBUTPP.
The difference in noise level for an mm preamp with shorting plugs vs. anything else plugged in is always an interesting sight. So yes, please give me a balanced connection from the cartridge to the preamp input. I use both MC and MM cartridges and your HMN won’t do both obviously.
How soon?
Hans, I’ve built and discarded three versions so far- they all worked, but two required parts that most people can’t get (e.g., 2SJ74) and one required some tricky adjustment. I *think* I have the right answer now… but you can count on balanced inputs.
Whiling away the days between the HMN and your MM design I have played with my own creation using a CineMag CMMI-2C and a triode strapped 6J9P. It does a few things right, but I don’t have the experience to avoid all pitfalls involved in radical departures from the norm. There must be better parts choices, if not lower costs, just around the corner.
Stuart, thank you for your response. I wouldn’t mind building with a couple 2SJ74 transistors. I have a few that are known to be real rather than fake. Using them in a balanced MM phono stage seems like a good idea compared to a tricky adjustment.
I’m just about to fire up my build of your HMN MC phono stage using the boards that jackinnj made available.
Best of luck! I saw a lovely build recently from a fellow who did one for himself and one for his company. Made me rather envious!
Do you have any pictures of those two HMN builds? I assume they were done using the pcb’s.
I am still struggling with getting heat sinks properly mounted to the parts that need them. There isn’t much room for them in a few places. Any visuals of successful attempts would be much appreciated.
Hans, everything is packed away at the moment (we’re in the process of moving), but I’ll try to post some pictures after we’re arrived and unpacked. One clue: only one of the transistors in each CCS might need a heatsink, the one with most of the voltage across it. And the heatsinks needn’t be very big.
Dear SY,
I have one question about the His Master’s Noise phono Preamp power supply.How to calculate the the high voltage output,base on normal serial regulator,the Vout=Vref*(1+R1/R2),The R1 is +260v output 220K and R2 is 8K2,The output should be 192V,not +260V,So please help me to understand it.You comments will be great appreciate it.
Best Wich
xiaojun
Xiaojun- Because the hfe of the error amp transistor can vary as can the reference voltage, the regulator may need trimming to hit the desired output (these were the values I ended up with in my build). You can trim the output voltage on test for your particular build by paralleling another resistor with the 8k2 if your output is too low, or across the 220k if your output is too high.
Dear SY,thank you so much for you input.
Hello Stuart
About one year ago i built your “His Masters Noise RIAA Preamp and i am happy with it, thank you! Now since i am pensioner i would like to build something complete different (also RIAA). I have some Parts for long, but they suggest to use a Western 437A for the outputstage. This Tubes are so crazy expensive, i can and will not buy this. But i have WE 436A (Tetrode). I know you are specialist in connecting Tubes to Triode. Do you think i can use this connected to Triode with a good Result?
Thank you so much for your Help,
Kind Regards Walter
Guten Tag, Walter! Just for clarity, are you proposing to use the 436 in the second gain stage or for the cathode follower?
Hi Dear Stuart, I got a board from a Diy member I can not remember, I forgot completely and right now I will finish the project, but I noted that in the board is place for IR830 that is a different animal to the original one that come with a deplection mode Mosfet.
Could you send me some information if is available in your knowledge about this boards ?
I am Diyaudio Member my nick is dady.
I living in Spain
Best Regards
Ola Esteban! I would guess the board was from jackinnj from diyAudio. I think the CCS MOSFETs were still depletion mode but the IRF830 might have been used for the regulator pass element. Jack still participates at diyAudio and might have more information.
The two updates I would make: reduce the current for the first stage (D3a) to 10mA and the second stage (ECC88) to 5mA. Not critical, but the unit will run cooler and performance will be just as good.
Stuart, I loved your article and I built your phono preamp, and am starting to trim the RIAA. You say to set the buildout resistor R7 so that the 50Hz response is 20dB above the 1kHz response. Why is that? I thought the 50Hz response should be about 16.95dB above the 1kHz response. Even the 20Hz response is only 19.3 dB above.
Also, I assume that you meant to adjust C2 for the 20kHz response. C4 is the 2.2uF output cap.
Thanks for a great design.
Mike
That’s a typo- the 1kHz gain should be about 20dB lower than the 20Hz gain (19.3dB to be more exact, as you said). Thanks for catching that!
Appreciate the kind words- I still use this preamp all these years later and have had little urge to change for MC.
Thanks for the clarification. That definitely makes things easier. Can’t wait to start using it.
Mike
Let me know how you like it once it’s up and running!
Sy,
I am pulling my hair out. I can’t get my hmnpp is work. I am bringing up the voltage with a variac. Everything looks good and then slowly dc appears at the output. MVolts at first and then it goes runaway, full out b+ 305 volts. Dangerous b+ on the gnd – I’ve been zapped. What is it a bad? MOSFET? I’ve changed them once.
You likely have a wiring error- the output is capacitively coupled, so there should be essentially zero offset.
StuaT,
I consider myself a beginner and have now for more than 40 years. I finally got my/your hmnpa up and running.
It’s really wonderful and i learned a lot. I bought the sowter 1480 which is a newer version of the 8055 i think. My cartridge is a spu at 2 ohms and the secondary resistance of the 1480 is 100 ohms . What would be the best value of the 6.8k resistor in this case?
One note i want to tell you about. Early on in the project I bought a set of pcbs from a fellow diyaudio guy, frank wilker. He had sold them as working and needing a case etc. Well his heater supply was terribly wrong, he had installed the diodes on the negative supply backwards. So I didn’t pick this up and had only tested it on the positive side. And so when I had it all ready to go the things worked initially but with in a minute the whole chassis went to 270+ volts, and threw a lightning bolt,- man that was the scariest and stupidest thing I have done in all of my lectronics life. I took some time off and beside still wanting to knock someones teeth out I am back building again.
I send you some pics it looks good too!
The loading resistor on the secondary is something that you’ll have to determine experimentally. If it sounds good as-is, then don’t sweat it too much.
Congrats on the build! It’s not an easy project and most people don’t get across the finish line.
Sy,
C12, C16 – 0.1uF, whats best type of capacitor to use here, ceramic, MKP etc?.
Cant find much info on this outside of datasheet.
Thanks
I’d use metallized polypropylene, cheap, easy to get, excellent mechanical and thermal characteristics, high performance. Use an industrial brand (e.g., Vishay, Panasonic, Wima…). Polystyrene is thermally sensitive, Teflon is mechanically poor, polycarbonate would be fine if it were available. Polyester (e.g., Mylar) will also work fine, though there may be some minuscule measured difference if you live in a high humidity area. If you want to be a contrarian and have the money and space, NP0 ceramic will also perform well.
Thanks, perfect I have some 0.1 WIMA MKP which I can use.
In keeping with what I have, I assume 10uF electro Nichicon KZ at ADJ pin and 120uF electro silmic 2 at output of regulator are acceptable.
Even less critical. I would use at least 105°C rated electrolytics for long term reliability.
Thanks, please – no need to post this comment and clutter up your board – if you could reply via quick email to the address that would be great.
If not, thank you for the help and I assume my question is below irrelevant and shall proceed accordingly.
Q: Trying to use what I have on hand – The 0.1/63V I have are actually FKP, (and not MKP) should be no problem?.
Thanks again.
JP
You are correct- no problem. FKP handle higher currents, which isn’t needed here but causes no harm.