|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
173.185.144.131
In Reply to: RE: Sample Sine Wave posted by deafbykhorns on February 23, 2019 at 16:51:37
1/2 of a 6sn7
Edits: 02/24/19Follow Ups:
According to my simulation, your 845 is starting to pull grid current at about 3 volts output (about 1 watt) using your operating points. Your 6SN7 driver is not going to do its job alone. Your sine wave isn't clipping but it sure is producing harmonics (on paper). It would be interesting to see what the real harmonics would be using your OPT. Depending on your music source, your probably not picking up on the harmonics but they are definitely there according to your scope. What is your plate and cathode resistor values.
You should look into a UMC204HD and the free ARTA Software. You get a scope, THD, FFT along with many other features. Its easy to implement and setup, I set it up in an hour. It's not too bad and reads very close to my HP Distortion analyzer.
Edits: 02/24/19
What would happen if I used both halves of the 6sn7 in srpp?
I'm not an expert in SRPP but I don't think so. It may help the output impedance and distortion but it wont provide grid current.
An IT transformer or a mosfet (grid drive) would be better suited for this or run the voltage up a little higher.
With your current driver and voltage, not sure you will get more than a couple watts on a low voltage 845. Those transmitting tubes start pulling grid current early.
You can do better using a 300B and its easier to drive. I would use some DHT's to drive it as well.
Actually, I can live with a couple of good watts with my Altec's. I am playing one channel in mono right now, and I do believe it would play more than loud enough for my tastes with a stereo pair. Sooooooo, before I spend any more effort on this project I am going to breadboard the other channel and see how it compares to my SET 2A3. That is the amp it has to beat to stay in my permanent setup. I already determined a while back that I like the SET 2A3 better than the 300B model 91 clone it replaced.
Edits: 02/25/19
If your are referring to the WE 91 you probably didn't like it because of the pentode drivers.
That sounds like a good candidate for another breadboard project one of these days. Would you happen to have a schematic of a good one you would be willing to share?
You don't really need much of a schematic, simply run any DHT at its op point and couple it with a cap.
Here's one I did back in the day, i got about 6-8 watts depending on transformer
nt
.
Have Fun and Enjoy the Music
"Still Working the Problem"
I got the following values with the amp turned on, no signal.
plate volts pin 2 to pin 3 103.7 vdc
grid volts pin 1 to pin 3 1.31 vdc
bias volts pin 3 to pin 1 minus pin 1 to grnd 1.31 vdc
how much plate current?
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
It's got a 1.5vdc nmh battery from the cathode to ground. How do you figure the plate current with that arrangement?
Measure the voltage across the plate resistor.
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: