1. Paramour: Top Level Link.
             10% Distortion Tables vs Frequency. Output impedance vs Frequency.

2. Paramour: Stock Output Transformer, Stock  Choke, AVVT 2A3 M tubes,
             Right Amp, 10% distortion pictures, No distortion curves.
             This link opens a new window so you can compare it to other pages.

3. Paramour: Stock Output Transformer, EXO-04 Choke, AVVT 2A3 M tubes,
             Right Amp, 10% distortion pictures, distortion curves.

4. Paramour: Stock Output Transformer, Stock  Choke, Sino 2A3 tubes,
             Left Amp,  10% distortion pictures, distortion curves and pictures.

5. Paramour: Stock Output Transformer, Stock  Choke, AVVT 2A3 tubes,
             Left Amp,  10% distortion pictures, distortion curves.

6. Paramour: EXO-45-VS Output Transformer, Stock  Choke, AVVT 2A3 tubes,
             Left Amp,  10% distortion pictures, distortion curves,
             50 Hz 100 Hz distortion curve comparison.

7. Paramour: EXO-45-VS Output Transformer, EXO-04 Choke, AVVT 2A3 tubes
             Right Amp, 10% distortion pictures, distortion curves.

First I needed to decide where to put the EXO-04 because 5 new holes need to be drilled in the Paramour chassis to mount the inductor.

After I removed the tubes and the old inductor, I inspected the wiring in the chassis for shorts and then applied 115V AC power to the Paramour with the Paramour sitting on it's feet like normal. With an AC voltmeter across the EXO-04 leads I rotated and moved the EXO-04 so that I could find the minimum induced voltage on the EXO-04 leads. I saw a maximum of 0.475V and a minimum of 0.032V. The minimum occurred with the inductor's gap facing away from the power transformer and with the iron of the inductor centered with the power transformer.

The test to find the best location would have been better if I wired up the old inductor a foot or two from the Paramour and put the tubes in. I did not do it that way for several reasons.

1. It is a good way to get shocked.
2. It is a good way to burn a forearm on a hot tube.
3. It is a good way to bump an expensive tube with a heavy piece of iron and break the tube and possibly get shocked again.
4. There should be enough magnetizing current in the line transformer that the best location for the choke won't change that much with out the load from the tubes.

To determine which lead of the inductor has the least capacitance to the frame of the inductor,  I drove the EXO-04 with a 10.5V pp 1 kHz sinewave from an audio generator and measured the voltage from chassis to audio generator ground.

With the Red inductor lead driven with 10.5 V pp.  I measured 4 V pp. on the frame.
With the Black inductor lead driven with 10.5V pp. I measured 1 V pp. on the frame.

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Pictures with the Stock Plate Choke Replaced with an EXO-04
Pictures taken at 10% distortion into 8.45 ohms (Right Amplifier).
An old HP 334 was used to measure the distortion.
First edition 14-Apr-01, Last update 21-Apr-01

Paramour with EXO-04 Plate Choke at 1 kHz, 2V/ div, 100 usec/ div, 10% distortion into 8.45 ohms. The bottom of the waveform is clean.

Paramour with EXO-04 Plate Choke at 100 Hz, 2V/ div, 1 msec/ div, 10% distortion. (6.1 V rms = 4.4 W)

Left is Paramour with EXO-04 Plate Choke at 50 Hz, 2V/ div, 2 msec/ div, 10% distortion. (5.7 V rms = 3.8 W: 2.9 dB more power than stock.) (Composite picture.)
Right is Stock Paramour at 50 Hz, 2V/ div 2 msec/ div, 10% distortion. (4.1 V rms = 2.0 W)

The 50 Hz waveform above looks similar to the 100 Hz waveform with the stock plate choke.

Paramour with EXO-04 Plate Choke at 20 Hz, 2V/ div, 5 msec/ div, 10% distortion. (2.05 V rms = 0.50 W: 2.0 dB more power than stock.) (Composite picture.)

Notes for Chart 1:
1. I took these distortion measurements with a Heathkit Sinewave generator that was sending 1.0 % distortion at 100 Hz and 1.5 % distortion at 50 Hz to the Paramour before the Paramour added any distortion of its own.
2. I could manually null the HP334A I was using better than the autonull would work. (Old test equipment is so much fun ;-).)

Chart 1: Paramour with EXO-04 Plate Choke: Distortion vs Output Power into 8.45 ohms on 8 ohm tap with AVVT 2A3 M output tube.