Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: ClippIn4tae on October 03, 2017, 07:11:44 pm
-
Can these 6973 tubes be widely used in other circuits easily?
I see that the screen voltage needs to be lower than a 6v6.
I was wondering about using some in a fender style circuit.
Any one know about this?
Will there need to be any mods other than the obvious pinout?
Thanks guys
-
Your best source of information is the datasheet
https://frank.pocnet.net/sheets/049/6/6973.pdf (https://frank.pocnet.net/sheets/049/6/6973.pdf)
I would not exceed the recommended maximum screen ratings for the class of operation you are going to run the tubes in
-
Your best source of information is the datasheet
https://frank.pocnet.net/sheets/049/6/6973.pdf (https://frank.pocnet.net/sheets/049/6/6973.pdf)
I would not exceed the recommended maximum screen ratings for the class of operation you are going to run the tubes in
According to that datasheet, the max voltage for both screen and plate are 410v which is higher than the same limits for a 6V6!
Of course, decades of testing in dozens of designs reveals that 6V6s can be run above their ratings by large amounts and survive, at least long enough to be "acceptable" for major amp companies and their customers. But with the 6973s, it likely is a good idea to stick within those ratings, so they might still be "weaker" than 6V6s in practice.
-
So with being said would it be feasable to run them in a ab763 style circuit with the same values of resistors? My plate voltage on the 6v6s were 315 at highest. And 300 <on screens....i think i have a set up that will allow it quite well
I just would love to try them in that deluxe cirucit.
Would ir be safer fixed or cathode bias from your looking at the tube data sheets?
Truth be told i need to learn how to read the data sheets. I dont knie how you came up with the numbers you did .i must learn.thanks any and all info is very welcome.
-
Replied to your PM
-
Thanks
-
FWIW, here's an example of how to put together a tube regulated screen supply (this one delivers 300V).
If your plate voltage was 400, you'd need to have different resistor values in the voltage divider that sets the grid voltage in the triode
-
Here's another (slightly simpler) example of a tetrode (KT61, but you could use a 6V6) as a screen supply regulator. You would adjust the voltage divider values at the tetrode's grid (pin 5 in this instance) to set the regulator's output voltage
-
Truth be told i need to learn how to read the data sheets. I dont knie how you came up with the numbers you did .i must learn.thanks any and all info is very welcome.
So I actually screwed up reading the datasheet! Tubeswell was right to make sure you're looking at the numbers for the class of operation you're using.
Class A vs. AB vs. B is a fuzzy distinction (in push pull amps), but you should be familiar with single ended vs. push-pull circuits. Push-Pull AF Power Amplifier -- Class AB1 is where we're looking. There's a sub-heading "Maximum Ratings" and "Grid No 2 (screen-grid) voltage" is listed as 330v.
There is a later section under a similar heading but it has the following information: "Grid No 2 of each tube connected to tap on plate winding of output transformer" which is not typical for guitar amps. That's where I incorrectly looked when I found 410v.
Basically, go through the datasheet slowly to find the characteristics which match your amp, and don't skip information (like I did). If there's something you're not familiar with, just stop and ask somebody, and you'll get comfortable with it pretty quick.
-
Yeah basically look at this picture. This is from the previously mentioned link and the data that Tubeswell quoted. It should give you an idea of what you're looking for.
~Phil
-
Thanks so much gentlemen!