This page is: "3. Paramour: Stock Output Transformer, EXO-04 Choke, AVVT 2A3 M tubes, Right Amp, 10% distortion pictures, distortion curves."
This involves working with high voltages, attempt
these changes at your own risk.
Many people refer to magnetics as "iron" no
matter what the magnetics are made of.
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.
Pictures of the Speaker Output Waveform from the Paramour
Stock Output Transformer
EXO-04 Plate Choke
AVVT 2A3 M tubes.
Pictures are taken at 10% distortion into 8.45 ohms
at the 8 ohm speaker output (Right Amplifier).
An old HP 334A was used to measure the distortion.
Added 04/13/01 Updated 04/13/01
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.Next I had to decide which lead of the EXO-04 went to B+ and which lead goes to the tube. The EXO-04 is electrostatically shielded by the end bells so I don't have to worry about "inductor to driver tube" capacitive coupling. I only have to worry about capacitive loading on the power tube. This means I want to attach the lead of the inductor with the least capacitance to the inductor frame to the plate of the output tube.
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.This means the Black lead has the least capacitance to the frame. The Black lead gets attached to the plate of the 2A3 and the Red lead goes to B+.
With the Black inductor lead driven with 10.5V pp. I measured 1 V pp. on the frame.
Paramour with EXO-04 Plate Choke at 10 kHz, 2V/ div, 10 usec/ div, 10% distortion into 8.45 ohms. The bottom of the waveform is clean.
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.
