
Home  Forums  Rules  Articles  The diyAudio Store  Gallery  Blogs  Register  Donations  FAQ  Calendar  Search  Today's Posts  Mark Forums Read  Search 
Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum 

Please consider donating to help us continue to serve you.
Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving 

Thread Tools  Search this Thread 
25th March 2009, 09:41 PM  #1 
diyAudio Member
Join Date: Jan 2009

Dumb Question Brain is numb today!
I know I will get a bunch of posts calling me a flake but I need help.
Using a triode curve for a SINGLE section of a dual Triode. I am trying to plot some load lines for the two sections in Parallel. Voltage stays the same, current doubles, but what do I plot for the Load ? Twice the OPT or Half or Same (assuming I double the plate current on the graph)??? 
26th March 2009, 02:26 AM  #2 
diyAudio Member

Plot it with a single plate characteristic using half the current and twice the load resistance.

26th March 2009, 02:41 AM  #3 
diyAudio Member
Join Date: Jan 2007
Location: Cypress Texas

Twice the plate load,,, in parallel,,,, wouldn't it be half the plate load?
Or did I miss something? Nick 
26th March 2009, 02:54 AM  #4 
diyAudio Member
Join Date: Nov 2007

doesn't twice the load resistance = half the plate load?

26th March 2009, 03:01 AM  #5 
diyAudio Member
Join Date: Jan 2007
Location: Cypress Texas

If so I've learned something, which would be a good thing LOL.
Nick 
26th March 2009, 03:19 AM  #6 
diyAudio Member
Join Date: Nov 2007

Well, I've always thought of a large load as a small resistance. I mean its like gear ratios, high gears are lower numerically. Are we talking about a large number or a heavy load for the amplifier stage?

26th March 2009, 04:02 AM  #7 
diyAudio Member
Join Date: Oct 2004
Location: Maui, Hawai'i, USA

It seems that there's some confusion as to what you mean in postulating your paralleled pair of tubes. If you are looking at a set of plate curves, and have settled on an operating point of x volts and y milliamps, and have figgered the gm, rp and µ for this condition, with the two devices in the envelope operating in parallel (assuming they are identical):
rp will halve gm will double µ, and thus circuit gain will thus remain the same optimum load, though (which is a function of rp) will halve current drive into the load (if it is a difficult one like an 845, this is a real improvement) will double. Did I explain that okay? Poinz AudioTropic 
26th March 2009, 12:44 PM  #8 
diyAudio Member
Join Date: Jan 2009

I think I understand,
Using a single plate curve, Plot with twice the load resistance and then I can double the currents for what will actually flow at any given grid voltage? Example,(made up numbers) if Idle current is 30mA @ Plate Volt 200V with 30 Grid Plot it out on the curve using an 8K load. Gives Imax of 50ma and Imin of 10ma So in parallel into the ACTUAL Impedance of 4K I have Imax 100mA Io 60mA and Imin 20mA...correct Voltages stay the same so Pout is 2x the single with twice the load Distortion should be the same? 
27th March 2009, 03:57 AM  #9 
diyAudio Member
Join Date: Jan 2007
Location: Cypress Texas

Ok ,, I could be wrong but, let go back to simple ohms law. How do you double the load resistance and double the current draw. These 2 are inverse of each other,,,, aren't they???
Nick 
28th March 2009, 05:25 PM  #10  
diyAudio Member
Join Date: Nov 2007

Quote:


Thread Tools  Search this Thread 


Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Dumb question, but...  johnm  Tubes / Valves  3  13th June 2008 10:14 PM 
music, trance, and brain chemistry question  faustian bargin  Music  15  7th July 2006 06:07 PM 
Brain GT 3886 PS question  lgreen  Chip Amps  10  5th April 2005 08:06 PM 
maybe this is too dumb a question...  dannyspencer  Solid State  6  18th April 2004 04:57 PM 
New To Site?  Need Help? 