Vinyl record playback MD pre amplifier (magnetic dynamic, electronic schematic) RIAA

[@RODALCO2007]

Good circuit. Newer Amplifiers haven't got the RIAA circuit. good to build as an add on for one of those.

[@radiofun232]

Thanks.

[@82levy5]

Can you please tell abour the functionality of the potentioneters?

[@radiofun232]

P1 is responsible for the overall amplification. Reason: different MD pickup elements give out different voltages, often in the 1 millivolt up to 5 millivolt range. P2 (500K) is part of the RIAA filter. Turn it till the RIAA correction works properly (bass & treble good, nice sound while playing a vinyl record). After that, take it out, measure its Ohms resistance and replace it by a fixed value resistor of the same value. P3 (1K) sets the amplification level of the pre-amp end transistor. Turn it to a position where all works fine (no overdrive of your end-amplifier), take it out, measure its Ohms resistance and replace it with a fixed value resistor of the same value. Reason: different audio end amplifiers can have different sensitivities on their inputs. For lazy people: turn P1 and P2 and P3 till all works fine (RIAA correction and pre-amp amplification = nice sound while playing a vinyl record), that takes a minute, and leave the circuit as it is. 12 nov 2022.

[@radiofun232]

And why 2 potentiometers to set the amplification? (P1 and P3). Has to do with the noise level. P1 is set to an amplification where the noise level is minimum. Noise level can only be seen with the help of an oscilloscope. Reason: the signal level of an MD element is extremely low, can be 1 millivolt = 1/1000 of a Volt. Every first stage in an amplifier of any kind must be as low-noise as possible, because the noise of that first transistor/FET/LNB/radio tube/ etc, etc, whatever kind of electronic first stage "receiver" that gets the signal, is amplified over all the other amplifier stages. That is e.g. the reason why the first stage of critical amplifiers (say to receive signals out of the universe via radio telescopes) are cooled with (say) liquid Helium, dropping the noise of the first semiconductor(s) or tube(s) or whatever other unit(s) down as much as possible. The Boltzmann constant formula gives good info here. Severe cooling drops also down the so called schot noise (in Dutch: schrootruis, litt. translation = shrot noise), that is also pressed down in this case, by giving that first transistor exactly the right voltage via P1. Shrot/shot noise is caused by random movements of electrons when they pass a semiconductor or a radio tube. Is for a big part related to the temperature of the electronic circuit. More noise reduction (theory, only visible via an oscilloscope) can be realized by using low noise resistors in that first stage, say metal-film resistors instead of carbon-film resistors. Thanks. 12 nov 2022.

[@mechanicantiquesrestoratio8738]

l need for the crystal cartridge mono preamplifier circuit... Can you help ? Please

[@radiofun232]

What kind of crystal cartridge? Can you mention the type number or manufacturer?

[@mechanicantiquesrestoratio8738]

@@radiofun232 l would like to send you picture about the type of crystal cartridges which l work on ..but impossibble to send you photo from this page .

[@keideshramnanansingh815]

@@radiofun232 i have a High output NOS Ceramic cartridge, i need an 9v - 12v amplifier stage for my record player, Any circuits?

[@radiofun232]

@@keideshramnanansingh815 Ceramic phono cartidges need RIAA correction, that is all. Any 1 transistor amplifier can be used, though the AC voltage output of a ceramic cartridge is so high (say 500-800 mV) that no amplifier is needed. In fact it is already on "line level" (say 0,8 V AC). The "amplifier" (thus) only has to give the necessary RIAA correction and (sometimes) even has to weaken the signal and/or make it possible to amplify "a little bit" because the RIAA correction R-C filter gives some loss. Even could be done with a passive filter. I don't have a specific 1 transistor audio pre amp for a ceramic phono cartridge on my YT Channel.

[@radiofun232]

@@keideshramnanansingh815 Perhaps this gives an idea about the RIAA principles. But this magnetic dynamic phono element amplifier works on 3-5 Millivolt input, so it will give an enormous distortion when driven by a ceramic cartridge that gives 300 mV-800 mV. A voltage divider can be used, but better: perhaps you can find something on the www.kzbin.info/www/bejne/i5uwZJ6VpJt_nas

[@beatlesadeye4912]

Sir, in the 'correcting element part' what is the: P2/500k ,is it preset?,and 2N2 500k(what is symbol mean).what is the 150p. And what is 1 N. Can this circuit be given 12 v? And this circuit is for magnetic cartridge I guess. And magneto element is the cartridge. For stereophonic ,two identical circuit have to be built?

[@radiofun232]

500 K is a potentiometer of 500000 (five hundred thousand) Ohms. It is a potentiometer because only in that way you can align the sound and the RIAA properties of all kinds of magnetic cartridges to your need, correcting the frequency response 20 Hertz-18 KHz of the MD element. 150 P = 150 Picofarad. 1N=1000 pF (=Picofarad) and 2N2=2200 pF. It was made for 18 Volt, so the performance on 12 V is not guaranteed, but worth to give it a try. For 12 Volt change the collector resistor of the second transistor = BC 547 b in the circuit to 3K3 = 3300 Ohm (instead of 1K = 1000 Ohm) for more success. And yes, for stereo 2 of these pre-amps must be made. Use the "one and only earth point" approach, much more about that in my video's on YT. Shield everything well with tin plate, connect that tin plate shielding to the one-and-only earth point (minus power supply) with an insulated wire.

[@radiofun232]

This vid shows good principles about how to make that, apart from many other vids on my channel kzbin.info/www/bejne/oqalnoxuiN96npI

[@vibra64]

The 500k pot, P2, when and why will you adjust that?

[@radiofun232]

It is part of the filter, so it will influence the sound. I built the circuit long ago, I can't remember the effect.

[@yoramstein]

Nice video

[@radiofun232]

Thanks, I did my best to explain it as good as possible, apart from the pronounciation issues.

[@yoramstein]

Your way of building the circuit is original. I have never seen anybody does it that way (nails) before.Your pronouciation is typical Dutch- no problem with that.