6V6 line preamp

[merlin el mago]

Isn't the same?

 

[Salas]

Electrostatic screen is internal thin metal tape but not shorted turn, for less capacitive coupling between primary and secondary. Opposes mains dirt noise to reach the secondary. Has a wire to channel what it collects to the mains grounded chassis.

Flux band is external loosely coupled thicker strap shorted turn to stop magnetic leakage. Works against radiated hum field. Not necessary to ground it. Some do also ground it.

 

[Salas]

You have seen flux band as a wide copper belt around Japanese EI transformers in classic good quality audio gear.

 

[merlin el mago]

Thanks!

 

[gmm4178]

Well, just to be clear. I think it's a good idea to pursue using the 6v6 as primary tube for an audio preamp.
I have no equipment that requires a preamp, like a turn table or such. But I hope offering such projects to others helps your business.

 

[merlin el mago]

Well, just to be clear. I think it's a good idea to pursue using the 6v6 as primary tube for an audio preamp.
I have no equipment that requires a preamp, like a turn table or such. But I hope offering such projects to others helps your business.

What business?

 

[gmm4178]

who ever sponsors this thread

 

[Pano]

@gmm4178 This is not the commercial section diyAudio. There is no sponsor.

 

[Lingwendil]

Well, just to be clear. I think it's a good idea to pursue using the 6v6 as primary tube for an audio preamp.
I have no equipment that requires a preamp, like a turn table or such. But I hope offering such projects to others helps your business.

this is a discussion thread for Salas' design. There is no commercial product on offer here, or promotion for one.

 

[gmm4178]

ok . my mistake . . . . .

 

[Salas]

Thanks!

Have you listened more to it by now? How is it coming across in the system?

 

[merlin el mago]

I'm sorry Salas no time to listen, I have problems with SSHV2 feeding the Valve Itch.

 

[merlin el mago]

Listened today it seems have less gain than the Valve Itch. What's the gain with the NFB used in mine schematic?

N. B. I use for NFB 55K + 500K

 

[Salas]

10.4dB (x3.31)

 

[Salas]

You could also try confirm with 1V RMS 1kHz sinewave from a function generator to the 6V6 build's input and measure its output. Possibly not exactly 3.31V RMS but should be there about.

 

[merlin el mago]

Thanks Salas.

 

[merlin el mago]

Following the good experience settings up well the SSHV2 for Valve Itch I revisited the 6V6 NFB PSU, one 220uF of the two in the BG gone so added one 820uF 550V Kemet and now the CCS set to 60mA without problems but still can't reach the 330Vout because the Vin SSHV2 is 325V so I left the B+ 300V waiting the new mains power transformer.

 

[vgeorge]

Gone where? What happened to the capacitor?

 

[merlin el mago]

Brymen "no Disc" so KO.

BTW the SQ increase a lot with the right 60mA of CCS, if the increase in SQ is the same pushing the B+ to 330-320V the perfomance of this preamp will be top notch.

 

[merlin el mago]

NoDac output 0,56Vrms x 3.31 = 1. 8536 a little bit below the 2Vrms.