half_Tube line driver

have been messing around with one half of 6sn7  as line driver...
very rich second harmonics! thinking of 8ch of it

any comments :

edit : final version  C1 1uf : R2 166r to 470r : R3 8K : 600ohm on output TRX secondary
or just copy second half of NYD 6sn7 design...

What load did you use when measuring the harmonics?

The 100K anode resistor is rather high. I suspect this plus the 2K2 cathode resistor means the tube is running at quite a low current. This means its output drive capability will be low and its output impedance relatively high both of which will result in higher levels of distortion.

Cheers

Ian

ruffrecords said:

What load did you use when measuring the harmonics?

The 100K anode resistor is rather high. I suspect this plus the 2K2 cathode resistor means the tube is running at quite a low current. This means its output drive capability will be low and its output impedance relatively high both of which will result in higher levels of distortion.

Cheers

Ian

Click to expand...

i was using my lynx 10K in 600r out.
yes, higher the input level is higher the distortion,  but very rich on 2nd harmonics.
i tried 47K and lower/higher cathode resistor, but then i am loosing the 2nd harmonics...
3rd harmonic is jumping in quickly.
its kind a sweet spot at the moment for 2nd harmonics, unless i push it really hard. 

(i was thinking this as 8 ch mixers ch input, when i mix 8 channels of stems/groups, none of the audio stems/groups would be that high to push the input to distort too much,
but under 1% THD, mainly 2nd harmonics.... )

frequency response is near flat, except there was a bump at 10hz when i measured with 1uf C1 cap.
then changed C1 to 0.22uf, but didnt measure it yet..


edit: when used the second half of tube, then things are more controllable (similar to NYD's design!)
but i like the idea of only one half for simplicity!

Hey Ian,
i made some changes re your comments! thanks for the input!

although 2k2 is still sounding good with 100K but
8k anode - 470r cathode resistor is bangon  8)
even when driven hard, distortion is still rich 2nd harmonics!

i got about 8db gain... i think i will be fine with it... i can ride the group faders from DAW anyway!

did some audio tests, sounding pretty damn good to me...
i can upload some drum and bass if anyone interested!

cheers

Interested with and without

Have you tried with a 600 ohm load on the secondary of the output transformer?

Cheers

Ian

ruffrecords said:

Have you tried with a 600 ohm load on the secondary of the output transformer?

Cheers

Ian

Click to expand...

ahhhh, just did that... it increased the THD a lot... from 1% to 8% 
edit : its reducing output level, so i have to drive it harder = more THD
attached the graph from RMA

i think i got it...
at 0db input, THD is only increasing 0.2 % with readjusted cathode resistor...
cathode resistor now 248 ohm (measured from pot)

edit :  hahah just checked NYD's design he used 250 ohm there with 10K anode... i dont have 10K or
another 2K in my watted resistor collection... i suppose, i will be fine with 10k  - 250r

here some audio files as is
(without 600ohm load)

https://spaces.hightail.com/receive/xPwP6
bpm is 100

You got it. With triodes, distortion increases with level but also with load.

Cheers

Ian

ruffrecords said:

You got it. With triodes, distortion increases with level but also with load.

Cheers

Ian

Click to expand...

thanks Ian