I don't see a reason to have differential amplifier after the cathodyne.
Amplifier with common cathode resistor was used In Williamson (Rk = 390 ohms).
The Williamson Amplifier
Amplifier with common cathode resistor was used In Williamson (Rk = 390 ohms).
The Williamson Amplifier
Better balanced condition as understand differential amp works more self adjusting due to those 'pseudo constant current tail resistor'. Noise supression is not a concern for my application. For this reason my initial question was - differential amp or regular gain stages with independent adjustment function ? and which are the differences in between ? First I noted from the answers the perfect balance it is not so much a concern. Second it was provided a simple way how to implement a differential solution. So now I understand a little bit I can try by myself and let you know my subjective conclusion. Thanks. Catalin
PS. my amp run pretty well with those 220 ohm in the cathodesame. It is just a opprtunity to learn something new and to see if I can improve some.
PS. my amp run pretty well with those 220 ohm in the cathodesame. It is just a opprtunity to learn something new and to see if I can improve some.
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Well, it is possible to achieve perfect balance with all the ciruits we have discussed.
Therefore one of the ciruits can not provide better balance than the other.
As I said before, the perfect balance of the phase inverter/driver stages does not mean anything if the output stage is not in perfect balance too.
And is it ? If not, as the case usually is, an AC-balance adjustment must be placed somewhere in the circuit.
There was a description at the Williamson link I gave, how to adjust the whole
amplifier to the balance. Have you noticed that ?
For learning and experiment purposes there is a great tool, LT Spice.
You can simulate all kind of tube circuits quickly and without soldering anything.
Therefore one of the ciruits can not provide better balance than the other.
As I said before, the perfect balance of the phase inverter/driver stages does not mean anything if the output stage is not in perfect balance too.
And is it ? If not, as the case usually is, an AC-balance adjustment must be placed somewhere in the circuit.
There was a description at the Williamson link I gave, how to adjust the whole
amplifier to the balance. Have you noticed that ?
For learning and experiment purposes there is a great tool, LT Spice.
You can simulate all kind of tube circuits quickly and without soldering anything.
Hello. found some similar into mcintosh ma 230 power stage. AC balance pot over the driver stage plate load. but big common resistor in cathode for differential mode.
I can elevate the cathodes till 100v from the ground.that is max acceptable cathode to heater voltage for el84. biased related to cathodyne 80-85v and direct coupling. That.s enough ecart and input voltage will not overpass swinging capability of el84 even I will supply at 460v. Then 1k pot between driver plates to adjust the AC balance. That means 10 percent. I.m not sure what kind of pot to use there to be safe.
What do you think.it worth? Thanks
I can elevate the cathodes till 100v from the ground.that is max acceptable cathode to heater voltage for el84. biased related to cathodyne 80-85v and direct coupling. That.s enough ecart and input voltage will not overpass swinging capability of el84 even I will supply at 460v. Then 1k pot between driver plates to adjust the AC balance. That means 10 percent. I.m not sure what kind of pot to use there to be safe.
What do you think.it worth? Thanks
That is not a driver stage. It is a DC coupled Long-Tailed pair phase inverter.
See attachment.
See also these:
The Valve Wizard
http://www.angelfire.com/electronic/funwithtubes/Amp-DB_Heart.html
Your circuit has essentially different topology, i.e. cathodyne phase splitter followed by a common cathode dual amplifier/driver.
Attachments
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Hello.
Can I add a little bit NFB (say 6-10db) in the end of driver stage, please? The amp did not work so well in bass with all loudspeakers I have even with UL connection so I can consider to raise the damping factor a bit. Please let me know if I can inject some NFB in point 4 in driver stage ? Thanks.
Can I add a little bit NFB (say 6-10db) in the end of driver stage, please? The amp did not work so well in bass with all loudspeakers I have even with UL connection so I can consider to raise the damping factor a bit. Please let me know if I can inject some NFB in point 4 in driver stage ? Thanks.
An externally hosted image should be here but it was not working when we last tested it.
It is not clear to me if I can apply nfb into common cathode resistor of differential driver stage or should I apply diferential nfb into separate cathode resistors?that means no diferential driver amp anymore...My first option is to place nfb into differential cathode common resistor but I.m mot sure if this stage can manage nfb...can you help me please?
Thanks
Thanks
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