Need 396A/6N3P/2C51/407A spice model

[mach1]

phn,

the 1k 'gridstopper' is not a gridstopper at all as it is on the output cathode. Ultrasonic ringing on the output can be a problem with transformer coupled linestages that can be addressed by loading, but is not usually an issue with regular RC coupling. The gridstoppers shown on the Broskie circuit should tame any tendency towards RF misbehaviour.

I fail to see how the 100k 'pulldown resistor' could promote a more constant current draw, as all DC is effectively blocked from flowing through it by the 5uF output capacitor. The Broskie circuit, however, has been carefully designed to achieve this outcome under dynamic conditions by balancing the ratio of the resistors used to bias V1 with those for V2. If you check you will find that the sum of the resistance for V2 = approx 0.9 that for V1 (as far as the power supply is concerned V1 and V2 are in antiphase, and the 0.9 ratio adjusts for the cathode follower gain of 0.9)

If you use a 1M output resistor the input impedance of your power amp will be the primary determinant of the impedance the preamp sees, and (unless the power amp input impedance is quite low) you will therefore be able to use a smaller coupling cap.

Having said all this, If I were in your place I would probably go for the aikido which is a later and probably more effective design.

Arnold, the diode in the circuit fulfils a protective role only and has nothing to do with the performance of the linestage. Unfortunately, the link to the circuit no longer exists, so everthing I have stated here is from memory.


pm

[arnoldc]

thanks mach1 and robert

phn, goodluck on your project. I was hoping to see more 407A projects here as they're really cheap!

[phn]

Robert, I use B2 Spice Lite. I found it more intuitive (read simple) to use than the others I tried. But these models will probably do anyway. These are problems I think I can solve, as well as allow me to, hopefully, learn something. I assume most models around are not designed for B2 Spice anyway. Thanks for the models.

pm, I just fell in love with the 407A. I'm not really a fan of preamps. I prefer passive/transformer pre/line stages, meaning basically a volume pot. But they have their problems. I might go Aikido later. I'm still scouting.

Grid stopper? I'm learning, I'm learning.

arnoldc, Thanks. It would have been nice with a 407A tread here like the one on the 12B4.

[arnoldc]

arnoldc, Thanks. It would have been nice with a 407A tread here like the one on the 12B4.

let's make this one

I'll post my simple 407A (and cousins) schema once I get my non-work related USB drive connected on my notebook.

[bogdan_borko]

I have a pair of russian 6N3P tubes and I`d like to use them in the line stage...
Anyone knows are these tubes used in audio and where. I tried a simple (RC) stage and they sounded cold and chrisp...

any schematics?
cheers!

[Toropkin]

PSpice models for Russian tubes are here:

http://www.next-power.net/next-tube/ru/libs.php3

(file PSlib.zip)

[Toropkin]

"I have a pair of russian 6N3P tubes and I`d like to use them in the line stage...
Anyone knows are these tubes used in audio and where. I tried a simple (RC) stage and they sounded cold and chrisp...
any schematics?"

It is very good tube for DAC output, MM phono preamps, etc:

http://astral-for.narod.ru/index/tubes/riaa_fr.gif

http://www.metaleater.narod.ru/45.zip

http://64.233.183.104/search?q=cache...=clnk&cd=1</a>

http://www.tubecad.com/email_2001/e0829/page20.html

[arnoldc]

I haven't tried the 6N3P yet, but since you have it in prototype already, try 160V anode voltage and 9mA. 2V - 4V bias to suit your taste.

How are you operating it right now?

My friend just finished his 407A pre and told me his 26 pre beats it in openness, but the 407A pre beats the 26 pre in bass (tighter) and highs (cleaner). He's running his at 11mA.

[arnoldc]

phn, mach1,

my friend emailed me his 407A circuit which he finished last night.

he comments that,

1. "this is very likeable"
2. "when the led current was around 7ma it was a bit edgy but now at around 11mA its smooth"
3. "B+ around 165 i think if i use 5V4 around 175"
4. "1.9V" (when I asked for the bias voltage)
5. "but like this better than the (snipped) specially on vocals"
6. "(snipped, censored) bass!!" when I asked him what is the strongest character.
7. but he goes on to say, "deep musical but for me its great for vocals"

I asked him, compared to your 26?

1. "the 26 more airy. but the 407 is not lean ha."
2. "mids can fill up the whole room. mid highs are snappy. without being hard"
3. "overall i would say its better than my 26 by a hair. maybe if i try the 01A or the UX-112"

[mach1]

Thanks Arnold,

I think a new 407A thread might be needed shortly !

pm