Help about the 6SN7/5692 linestage

[BernardB]

Hello,

I am thinking to built the 6SN7/5692 dual mono linestage to use it with an dual mono kt88PP.
1 - Could you help me to choose between the two design from FDeGrove : what are the difference, advantage/disadvantage one versus the other

[commstech]

Build them and let us know what u think.

[kmtang]

Personally, I like the 2nd one with coupling capacitor in between the 6sn7. I have built a similar one which sounds pretty good.

Anyway, it is very easy to try both of them.

Johnny

[hacknet]

i prefer the direct coupled one. its always better to do without those pesky capacitors..!

[amperex]

I also prefer bottom schematic- direct coupled. Ultrawide bandwidth & no coupling cap to color sonics.

[rdf]

Can someone explain the note regarding stepped attenuators? Why would the type of pot determine the biasing scheme?

[BernardB]

Thanks

Sure with some small components more i can try the both, so i think i'll do it

[EC8010]

Originally posted by rdf
Can someone explain the note regarding stepped attenuators? Why would the type of pot determine the biasing scheme?

I expect that what the writer means is that switched attenuators tend to use switches with carefully machined studs and a wiper with quite high contact pressure, so their contact is more reliable than the wiper scraping over the delicate track of a potentiometer. Thus, it is sufficiently unlikely that the contact will be broken that the switch can be safely used as the grid leak resistor, whereas pots are notorious for failing wiper contacts. (Remember that if the grid-leak resistor fails, the triode becomes a diode and current is only limited by the anode load resistor.)

[porkchop61]

I built one very similar to this design, and was told that placing a diode between the screen and cathode of the 2nd half of the 6SN7 was adviseable for the tube to survive turn-on (Sy suggested this).
Glenn