Dynamic load line analysis using music and speaker load - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

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

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
Reply
 
Thread Tools Search this Thread
Old 7th March 2008, 09:47 PM   #1
diyAudio Member
 
Michael Koster's Avatar
 
Join Date: Jan 2008
Location: Eureka, 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.

Cheers,

Michael
Attached Files
File Type: pdf dynloadlines.pdf (98.1 KB, 36 views)
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Help with this dynamic test load imix500 Parts 29 21st February 2009 12:51 AM
load line UL v.s. triode mashaffer Tubes / Valves 7 23rd January 2008 01:58 AM
How 2 build a Dynamic Load tester? Zero Cool Solid State 2 20th September 2004 06:00 PM
Load line for CF mashaffer Tubes / Valves 4 2nd July 2004 06:13 AM


New To Site? Need Help?

All times are GMT. The time now is 12:51 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2