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Old 25th April 2011, 04:41 PM   #1
lineup is offline lineup  Sweden
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Default Listen to 6DJ8 Triode through Power Chip IC. Easy project.

The idea can be seen in diagram.
This is only a basic simplyfied schematic. I post in more details later.
Should be noted that these circuits are so far only in my SPICE.
But should work good and give fine performance.

Power chip OPA541 can fead 50 Watt into 8 Ohm.
Max rails are for the chip +/-35 = 70 Volt.
Here I run 6DJ8 and OPA541 at 66 Volt.
Even if OPA541 can amplify voltage, in this case it is used as buffer.
Voltage follower at unity gain.
What come in comes out to speakers.
Distortion is low and can not be perceived as effecting sound.

This means that 6DJ8 totally dominate the distortion, the effects on sound signal.

There are 2 alternative circuits.
One where Triode plateload is resistor, 100kOhm.
One where Triode plateload is a CCS constant current source.

Big difference where CCS gives near hifi performance
and resistor load gives more Triode Tube sound.

Enjoy
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Old 25th April 2011, 06:11 PM   #2
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Here is Alternative 1.
With resistor 100k as the plateload.

I think this can give Triode Sound as there is a bit distortion.
The output is at least 40 Watt and maybe upto something 50 WAtt.
At 1 Watt THD, mostly 2nd harmonic, 0.054%
At 40 Watt 0.446%
The voltage gain is x15.

See figure 1 for a compare THD with Alternative 2. CCS-loaded.
Figure 2 shows the complete circuit of Alt. 1.
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File Type: png Triode-Sound_resistor.png (35.2 KB, 203 views)
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Old 25th April 2011, 06:22 PM   #3
lineup is offline lineup  Sweden
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Here is Alternative 2.
With 2 transistors forming a CCS constant current source.
Distortion is low. Near to Hifi!

See figure 1 in previous post for THD figures.

This circuit below, or the one in post above, should be easy to build.
There are few parts and straight foward connections.
Need one transformer 2x24VAC ~200VA to give like 66 Volt DC.
Also some smaller transformer 9 to 12VAC for the heater feeding.

Enjoy
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Old 28th April 2011, 02:41 PM   #4
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Any thoughts?
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