Jan 18, 2008 11:42 pm I've done some basic stuff, not any load lines, but basic concept and dev work.
Don't MAKE me go to another forum
Posted on Jan 18, 2008 09:19 pm
colonel_sanders
edit0r
Member Since: Aug 17, 2004
Anybody know any tube guru's? I'm designing a half arsed amp and need some feeback/questions answered.
Thaaanks.
C_S
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Jan 18, 2008 11:42 pm I've done some basic stuff, not any load lines, but basic concept and dev work.
Jan 19, 2008 12:32 am Why, as a matter of fact, yes. I belong to this forum: www.antiqueradios.com/forums/index.php
These guys are tube gurus. Mostly radio & TV guys, but they can answer tube circuitry questions for sure. Try the fellas that hang in the vintage audio forum.
Jan 19, 2008 08:33 am Herb you sly dog, excellent work. Will be posting shortly.
pjk, I'm wondering if its possible to switch in 3 diffierent kinds on anode resistors using shunt Jfets/Mosfets? I think the voltage is too high, but I'm often wrong. I'll post a schematic soon to show what the hell I'm talking about...
Anybody know of a basic circuit design program as well? Just needs to have the component graphics, no testing or anything.
Thanks,
C_S
Jan 19, 2008 09:44 am here's a sch program I've used for quite awhile. Though with tubes, I often draw by hand.
www.expresspcb.com/Expres...ic_software.htm
There's also duncan amps' power supply designer II:
www.duncanamps.com/software.html
There's other things on the page too, just in case you want to pick and choose.
Now, as far as the Ra switcher, I dunno =).
I'm not versed with jfet/mosfet switching, so I have to pass on help there.
I just read the wiki on jfet, are you thinking to run a jfet as a Ra controller?
Hmm, that sounds aggressive. It will change the bias point of the tube, plus the characteristics, but I guess that's what you're looking for.
I suppose a 3p2t switch is out of the question?
There's a few tube amp boards I used to frequent,
ax84.com/bbs/index.php?area=1 &
www.webervst.com/vstbbs/bbs.html
There's spice modelers too, that'll give you outputs for circuit tests. I haven't gotten it to work much, but I haven't tried much either. I think duncan amps has spice stuff.
Jan 19, 2008 09:10 pm I'll take a look at the express PCB program.
Yea, 3 seperate jfet/mosfet and relay control voltages changing Ra, Rk/Ck, grid stops, filter values, and gain stage cascading in the preamp, operating classes and combination of output tubes, and a speaker selector in the power amp.
All switching needs to be electronic, and prefereably shunt, so 3p2t is out. My main concern is that a Jfet/Mosfet won't be able to handle the voltage across Ra. My research shows it'll be up at about 170/180V, but I'm not sure if the voltage matters if its a shunt switch?
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