Autoformer volume control problem
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Use a DC blocking cap.
The only two things that can cause you issues with the bass are unbalanced current or an extremely high source impedance (10K+)
dave
The only two things that can cause you issues with the bass are unbalanced current or an extremely high source impedance (10K+)
dave
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what sized capacitor?
I thought the autoformer was on the secondary of the lundahl transformer.
dave
I thought the autoformer was on the secondary of the lundahl transformer.
dave
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do the attenuation steps work as they should?
there isn't really a way to destroy them. can you measure the output DC resistance at every position of the 12 position switch?
dave
there isn't really a way to destroy them. can you measure the output DC resistance at every position of the 12 position switch?
dave
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1 pos. 0R3
2 pos. 0R8
3 pos. 1R1
4 pos. 1R5
5 pos. 2R1
6 pos. 3R1
7 pos. 4R7
8 pos. 7R2
9 pos.11R2
10 pos. 16R7
11 pos. 25R4
12 pos. 38R7
13 pos. 57R8
1 pos. 0R3
2 pos. 0R9
3 pos. 1R1
4 pos. 1R5
5 pos. 2R2
6 pos. 3R1
7 pos. 4R7
8 pos. 7R2
9 pos.11R2
10 pos. 16R7
11 pos. 25R7
12 pos. 38R9
13 pos. 58R1
2 pos. 0R8
3 pos. 1R1
4 pos. 1R5
5 pos. 2R1
6 pos. 3R1
7 pos. 4R7
8 pos. 7R2
9 pos.11R2
10 pos. 16R7
11 pos. 25R4
12 pos. 38R7
13 pos. 57R8
1 pos. 0R3
2 pos. 0R9
3 pos. 1R1
4 pos. 1R5
5 pos. 2R2
6 pos. 3R1
7 pos. 4R7
8 pos. 7R2
9 pos.11R2
10 pos. 16R7
11 pos. 25R7
12 pos. 38R9
13 pos. 58R1
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that is all correct. measure to see if there is and resistance from the coil to the core.
Does this behavior happen in both channels?
does it happen with every source?
dave
Does this behavior happen in both channels?
does it happen with every source?
dave
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I have no idea what the incompatibility could be since placing it at the output of a tube stage with a step down should completely isolate it from the source at the grid of the tube. Maybe ask on a twisted pear discussion site and point me there to discuss further.
dave
dave
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With the power off please measure the resistance to ground at the input of the autoformer at a few switch settings and report back (measure at the autoformer side of the 4uf coupling cap)
dave
dave
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The input should remain the same at all level settings and be about 58 ohms. The output should have the measured values like you say and like the table you provided earlier.
If you have the input and output reversed that would explain your issues.
dave
If you have the input and output reversed that would explain your issues.
dave
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you can restack them 1X1 on the laminations but you should have plenty of inductance now.
What is the output Z of the legato?
dave
What is the output Z of the legato?
dave
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Then changing the inductance will not appreciably change the bass.
You could try a butt gap ~20-25hy and see if that helps. (inductance will become more linear)
dave
You could try a butt gap ~20-25hy and see if that helps. (inductance will become more linear)
dave
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