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Old 13th Feb 2007, 10:11 am   #51
oldeurope
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Smile Re: making an audio output triode...

Quote:
Originally Posted by miller_effect View Post
The most interesting thread on the forum!
Excellent work!

Does it sound like a power triode?

The distortion doesn't seem quite in the same league as a PX4!
But it does seem to behave like a power triode.

Am I right in assuming most of the gain is in the combined output stage?
Is that why it's got both grid and anode stoppers?

So the combined output stage is an ECC82 with both systems in //?
What is the driver stage; half an ECC82?

Sorry, your circuit diag wasn't clear. Your circuit diag. shows only one triode stage in the output, but your description quotes two.

Great work.
I'd certainly give it a go, I'm interested in hybrid stuff like this.
Hi miller_effect,
I didn't test it in a living room. This comes up when the mains transformer and the mains input is mounted.
The PX4 has 4% destortion at 3,2Watts, AD1 has 5% at 4,2Watts...
These values are measured at the plate site without destortion of the driver stage and losses of the output transformer. My measurement is at the speaker terminals.
I don't like the "low micro" valves sound. This is a compromise to get a better efficiency. My oppinion is a micro between 10 to 20 gives the best sound.
The ECC82 has u=17 , the AD1 has u=4, the 300B has u=3,8 ,the EL34 triode u=11 ,the EL86 triode u=8, the EL84 triode u=19, the RL12T15 u=14,4. I like the RL12T15 and the EL84 triode very much, but they don't have enough power and it is difficult to find good RL12T15. So a "big" ECC82 is the thing I want. The triodelington application makes this possible!
There are various kinds of ECC82s out there, they all sound different if you don't have negative feedback and run them with nearly micro (u)!!! So I can select your sound.
Attached is a graph of a single system of the ECC82.(Valvo-Handbuch 1962-63)
Uieff is input voltage RMS in Volts on the left Y axis.
Ia is plate current in mA on the left Y axis.
Kges. is the "THD+N" distortion in % on the right Y axis.
No is the sound output power measured at the output resistor Ra. (X- axis)

I don't like this biasing and output load. I my amp I have both systems in parallel. The equivalent Rk for both systems is 1K2 and Ra = 20K. The output power must be multiplied by eleven.
I didn't find a graph for this application.

I will measure the gain exactly after making the schematic. I remember it is about -13 for the triodelington output stage (plate/grid), the driver stage makes -u (17).

What are stoppers?

Yes, 1/2 ECC82 for the driver stage and both systems in parallel at the triodelington.

The handmade graph at the beginning showes one single system in the triodelington (and I connected the heater wrong )

I'll draw a provisorial schematic soon .

Kind regards,
Darius
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Last edited by oldeurope; 13th Feb 2007 at 10:20 am. Reason: text
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