6N3 Preamp Question

[denny9167]

I found this schematic for a preamp that I want to use to drive 2 Mark IV mono amps,using an iPod for a source,so I don't need any gain but would like to have someting for both impedance matching,and switching for other sources. The schematic looks like a typical cathode follower,but I have a question,the second triode is directly coupled to the other triode,I'm not sure what I'm missing here,and would like suggestions on other mods if there needs to be,Thanks a million!!

[Alain Poitras]

Originally Posted by denny9167

I found this schematic for a preamp that I want to use to drive 2 Mark IV mono amps,using an iPod for a source,so I don't need any gain but would like to have someting for both impedance matching,and switching for other sources. The schematic looks like a typical cathode follower,but I have a question,the second triode is directly coupled to the other triode,I'm not sure what I'm missing here,and would like suggestions on other mods if there needs to be,Thanks a million!!

This is a "direct coupling", there is no need for a coupling capacitor and grid leak resistor ... There is 95V at the plate of the first tube and the grid of the second one, 99V at the cathode of the second tube, then the "bias" is -4V ...

The double triode is a chinese 6N3 or 6N3P or russian 6H3Π but a preamp like that can be made with any good double triode if you adjust the resistor to get the good bias and currents for the best operating points. R13 is a negative feedback resistor to reduce distortion.

The rectifier suppose to be a 6Z4 Shuguang but I think the pinout is wrong ... Anyway, you can use just about any full wave tube rectifier for this preamp, for example a 6CA4. You will just have to adjust the voltage dropping resistor "RO" 3K to get the 241V supply, for two channel of course because this schematic is for a monophonic preamplifier !

Alain.

[costis_n]

The first stage is grounded cathode, and it does have gain. the cathode follower is the3 second stage only. So, if you do not want gain, it is not for you. Also, people here say 6N3P is terrible for audio, although Yarland for example does use them.

[ovpopov65]

Originally Posted by costis_n

Also, people here say 6N3P is terrible for audio

This is not the case. 6N3P (ев) (made in Russia) good sounding tube. I successfully used it as a driver in a PP EL84 amplifier.

In the power supply, I would have applied the choke and parallel with the electrolytic capacitors, I would be hooked up film capacitors 2-4 uF / 400V.
PS
You do not like cats?

You just do not know how to cook them!

[costis_n]

Originally Posted by ovpopov65

This is not the case. 6N3P (ев) (made in Russia) good sounding tube. I successfully used it as a driver in a PP EL84 amplifier.

In the power supply, I would have applied the choke.

PS
You do not like cats?

You just do not know how to cook them!

I remember Wavebourne saying so, I just have them in a cheap Yarland I bought. So he said there are huge stocks and people in ex-CCCP want to get rid of them. It is not a coincidence you only find them in the cheapest amplifiers

PS your comment ruined my day, not that I like cats.

[ovpopov65]

In Russia, there are huge reserves of many things and it all sold. But that does not mean that everything is sold - it's bad.
People are greedy and crave for profit.

My comment was about the use of tubes 6N3P.

[costis_n]

of course it does not mean that everything is bad! Just the 6N3P is only good for RF. I buy this stock and it is very nice!

[ovpopov65]

Originally Posted by costis_n

Just the 6N3P is only good for RF.

[TheGimp]

I did some testing of the 6N3P a while back and found it to be quite acceptable for audio. I just don't like the non-standard heater pin out.

FireFly Single Ended Tetrode

[Alain Poitras]

Originally Posted by ovpopov65

This is not the case. 6N3P (ев) (made in Russia) good sounding tube. I successfully used it as a driver in a PP EL84 amplifier.

In the power supply, I would have applied the choke and parallel with the electrolytic capacitors, I would be hooked up film capacitors 2-4 uF / 400V.
PS
You do not like cats?

You just do not know how to cook them!

I am very interested using russian tubes in my audio projects exactly because there some very good ones, they are not very expensive and I am not rich ... Let the snobs spend their money buying all the 2A3 and 300B ...

About this forum background colors, for use with the standard HTML color code :

The light bakground is : CFCFEF
The dark background is : BBBBEB
The "quote" background is : E1E4F2

Example : Eating dog meat is better for health than hotdogs ...

Alain.