that's good, I believe it's like fishing. Give a man an amp and he plays till it broken, teach em to build an amp.............
I just got an 8-pack of 5964's. I see circuits with plate resistors between 36 ohms (what?!?) and 20 k.
I'm trying to (intelligently?) work through Kuehnel's analysis of the Fender Bassman 5F6-A and 'scale' it to the 5964, but I'm embarrassed enough to check in here first before I waste some more paper.
All I did was pick Vp=250 for and Ip = 4 mA for 5964 (62k ohms Rp) instead of 325 V and 3.25 mA (100k ohms Rp) for 12AY7. Something went ugly...probably my assumptions...
I'm trying to (intelligently?) work through Kuehnel's analysis of the Fender Bassman 5F6-A and 'scale' it to the 5964, but I'm embarrassed enough to check in here first before I waste some more paper.
All I did was pick Vp=250 for and Ip = 4 mA for 5964 (62k ohms Rp) instead of 325 V and 3.25 mA (100k ohms Rp) for 12AY7. Something went ugly...probably my assumptions...
Not replace in an actual Bassman, which isn’t possible for nearly every imaginable reason, but utilize 5964 in a low-power circuit inspired by the 5F6-A preamp stage.
I haven’t decided what the next couple stages will use but the output stage may be a small power pentode or dual tube like a 6BM8. Far too different from the inspiring circuit so some analysis is intended at each step and overall.
I haven’t decided what the next couple stages will use but the output stage may be a small power pentode or dual tube like a 6BM8. Far too different from the inspiring circuit so some analysis is intended at each step and overall.
Relevance to cannibal build theme/topic is that it may (TBD) use an old VTVM chassis with a broken meter and 6x 7-pin sockets (or replace two with 9-pin). Or not use that chassis for this project.
Basically trying to make the effort to ‘design’ a similar but different circuit with study and application of the analysis methods in Kuehnel’s book.
All I did so far was select a reduced plate voltage appropriate for 5964 and a plate current/load line for proportional plate dissipation to that of the 12AY7 5F6-A LTP. Both tubes have 1.5 W plates so the 1 W level seemed like a reasonable similarity to the 12AY7 usage. I’m walking through each step of circuit analysis with reflection on Kuehnel’s results. I’m trying to figure out what whether 250 V & 4 mA are really wrong choices for the 5964 or 6J6, or my next step of determining rp is misapplied. The 5964 datasheet says 250 V max. but many applications are at 100-150 V. I may have just thrown my first dart at the 5964 curves and made a humiliatingly poor first choice. It’s probably viable for some purpose but I was puzzled how I could end up with such a high value of rp. I can certainly make a different choice but think I screwed up step 2 which I have said nearly nothing about yet. I cleared the kitchen table of all my books & papers to accommodate weekend guests. I need to revisit and share the second plotted (grid?) line intersecting the 250 V 4 mA load line. That may be where my choices went wrong.
Basically trying to make the effort to ‘design’ a similar but different circuit with study and application of the analysis methods in Kuehnel’s book.
All I did so far was select a reduced plate voltage appropriate for 5964 and a plate current/load line for proportional plate dissipation to that of the 12AY7 5F6-A LTP. Both tubes have 1.5 W plates so the 1 W level seemed like a reasonable similarity to the 12AY7 usage. I’m walking through each step of circuit analysis with reflection on Kuehnel’s results. I’m trying to figure out what whether 250 V & 4 mA are really wrong choices for the 5964 or 6J6, or my next step of determining rp is misapplied. The 5964 datasheet says 250 V max. but many applications are at 100-150 V. I may have just thrown my first dart at the 5964 curves and made a humiliatingly poor first choice. It’s probably viable for some purpose but I was puzzled how I could end up with such a high value of rp. I can certainly make a different choice but think I screwed up step 2 which I have said nearly nothing about yet. I cleared the kitchen table of all my books & papers to accommodate weekend guests. I need to revisit and share the second plotted (grid?) line intersecting the 250 V 4 mA load line. That may be where my choices went wrong.
The 5964 is basically a 6J6 with a treated cathode such that it can withstand long periods of zero current operation, which will cause cathode poisoning (sickness.....whatever) on a common tube. The 6J6 has been used as an LTP in a few audio amps.
The 5963 is a similarly modified 12AU7, and the 5965 is a modified 12AY7.
The 5963 is a similarly modified 12AU7, and the 5965 is a modified 12AY7.
Well, small world!
Someone gave me some old (‘62-‘65) HP AC-4 Nixie counter modules...I got 3rd round scrap pickins’...someone had already gleaned the Nixies and the dual triodes. I was happy to get open chasses with 4x 9-pin sockets.
I just looked those up and at least one version used 5963’s. Higher freq. one used 6211.
I had not heard of 5963 and now have their little brothers.
Someone gave me some old (‘62-‘65) HP AC-4 Nixie counter modules...I got 3rd round scrap pickins’...someone had already gleaned the Nixies and the dual triodes. I was happy to get open chasses with 4x 9-pin sockets.
I just looked those up and at least one version used 5963’s. Higher freq. one used 6211.
I had not heard of 5963 and now have their little brothers.
I should delete my question on the basis of discovering a profoundly stupid error, but George’s mapping of dual-triode ‘digital’ tubes to their conventional cousins is useful.
If one gets a wrong resistance from a (v1-v2) /(i1-i2) graph that’s a nice straight line, well, it’s the wrong line (wrong slope) or the wrong place for it. Duh.
Reminds me of a 9th grade 1972 science class where I was supposed to plot my data and explain why it deviated from a straight line. I didn’t have graph paper (hey, I was poor!), so i drew an x-y axis and straight line through the origin (0,0), then put x,y grid lines through my data points. Perfect!
The teacher got flustered & said ‘you can’t do that! That...that...that’s a left-handed graph!’ Took her a moment to make sense of what I did and how to keep me from doing it again.
Believe it or not, I have survived working on tube gear off & on since the late 70’s, but I have never messed with tube curves. First time I get shocked, it’s from �� mishandling a datasheet.
If one gets a wrong resistance from a (v1-v2) /(i1-i2) graph that’s a nice straight line, well, it’s the wrong line (wrong slope) or the wrong place for it. Duh.
Reminds me of a 9th grade 1972 science class where I was supposed to plot my data and explain why it deviated from a straight line. I didn’t have graph paper (hey, I was poor!), so i drew an x-y axis and straight line through the origin (0,0), then put x,y grid lines through my data points. Perfect!
The teacher got flustered & said ‘you can’t do that! That...that...that’s a left-handed graph!’ Took her a moment to make sense of what I did and how to keep me from doing it again.
Believe it or not, I have survived working on tube gear off & on since the late 70’s, but I have never messed with tube curves. First time I get shocked, it’s from �� mishandling a datasheet.
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