Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Dynamic load line analysis using music and speaker load
Dynamic load line analysis using music and speaker load
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 7th March 2008, 08:47 PM   #1
Michael Koster is offline Michael Koster  United States
diyAudio Member
Michael Koster's Avatar
Join Date: Jan 2008
Location: Sunnyvale, CA
Default Dynamic load line analysis using music and speaker load

Another test I performed on the Complementary Current Mirror amplifier (Tube/MOSFET push-pull) was looking at the dynamic load lines for both the triode and MOSFET. They should be identical and they are.

But in the course of looking at the dynamic load lines I obtained some interesting plots.

Top left shows what I'm measuring. I set up my scope in x-y mode to plot anode voltage on one axis and anode current on the other, and took a picture of a purely resistive textbook RDH4 load line. I then superimposed the anode characteristic curve over the trace to show approximately where the load line belongs on the anode chart.

The rest of this row and the next show the load "line" when driving various sine wave frequencies into a JBL4312 loudspeaker. It becomes elliptical due to the reactance of the speaker and crossover. The impedance (angle) and phase (ellipse ratio) moves all over the place as frequency changes (as expected). 60 Hz seems to be a resonant peak in this box and indeed at lower damping factors it booms around this frequency.

The effect with music on the bottom row is as expected, but different kinds of music result in different shapes, etc. of load curves, from loopy to jagged to bushy. I think the bushy one had a lot of crunchy guitar and the loopy one was a smooth vocal + piano and a lot of bass.

It changes one's idea of the "load line" to look at it this way.

Anyway, I did prove that the current mirror does the "right thing" on the other side of the OPT and made some interesting observations.


Attached Files
File Type: pdf dynloadlines.pdf (98.1 KB, 54 views)
  Reply to this post


Dynamic load line analysis using music and speaker loadHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Help with this dynamic test load imix500 Parts 29 20th February 2009 11:51 PM
load line UL v.s. triode mashaffer Tubes / Valves 7 23rd January 2008 12:58 AM
How 2 build a Dynamic Load tester? Zero Cool Solid State 2 20th September 2004 05:00 PM
Load line for CF mashaffer Tubes / Valves 4 2nd July 2004 05:13 AM

New To Site? Need Help?

All times are GMT. The time now is 02:20 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio