distortion due to Miller non linearity - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

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 8th April 2005, 05:55 PM   #1
diyAudio Member
Join Date: Apr 2005
Location: Sydney
Default distortion due to Miller non linearity

I wonder has anyone done any research or are familiar with this concept. I recently designed and built a low THD headphone amplifier but the only way I could get THD to 0.001% across the audio band was to engage in time consuming analysis of data sheets and mass testing of devices for lowest and most linear junction capacitance. I eventually settled on Motorola bc549 / 559 for IS, VAS and current sources. The motorola devices achieved far better subjective and measured results than the other branded equivalents. The amplifier is basically a D. Self generic class A design with a few variations. I discovered that the IS current mirror was largely to blame for the Miller contributions mainly due to the low voltage across CB. I've ended up using Motorola MPSA18s in the current mirror because they offer the lowest Miller and also have the advantage of high beta. Not surprisingly they also achieved the best subjective result.

BTW, the output stage is complementary CFP using Toshiba 2SC5171 / 2SA1930 at 100mA qiescent. These really are fantastic devices.
Actually, I'm not really sure how low the THD is now because It's at or below the limits of my 24 bit analyser. By comparison my Musical Fidelity A32cr preamp looks very ordinary but in fairness the distortion is mainly 2nd order. Out of curiosity I compared the headphone amp (as a preamp) with the MF into the hi-fi. My CD source is a Marantz SA-11s1 which also plays SACD. After a week of listening I was finding myself more and more tending to listening to the home brew design due to slightly less grain and more hf detail. The difference was even more apparent on SACD.

The results are encouraging. I wasn't expecting to build something that outperformed a reasonable commercial product.

  Reply With Quote


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
Air-spring non-linearity, causes? thadman Multi-Way 18 14th April 2016 12:14 AM
DAC linearity test CD lcsaszar Digital Source 52 22nd May 2012 11:27 PM
Linearity maxpou Solid State 42 8th February 2008 10:44 PM
relation between ampere, voltage and distortion or linearity oliverniekamp Pass Labs 4 17th June 2002 08:38 PM

New To Site? Need Help?

All times are GMT. The time now is 07:17 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2