Transient Intermodulation Distortion

[oldphaser]

Here is a list of documents I have gathered on the subject or Transient Intermodulation Distortion over the last couple of years:

NOTE: I also have all of the AES papers. However, I cannot share them.

Audio Engineering Society Papers

(NOTE: Most AES/JAES papers are not free. In some cases there are some links to free pdf’s)

Circuit Design Modifications For Minimizing Transient Intermodulation Distortion in Audio Amplifiers by Matti Otala JAES Vol 20 Number 5 June 1972 pgs 396-399

Transient Intermodulation Distortion in Commercial Audio Amplifiers by M. Otala, R. Ensomaa JAES (Project Notes/Engineering Briefs) Vol. 22 Number 4 pp. 244-246 May 1974

A method for Measuring Transient Intermodulation Distortion by Eero Leinon, Matti Otala, John Curl AES preprint no 1185 presented at 55th convention, November 1976 and JAES Volume 25 Issue 4 pp. 170-177; April 1977 NOTE: This link takes you a pdf

Method for Measuring Transient Intermodulation Distortion (TIM) by Eero Leinonen, Matti Otala, John Curl Paper 1185 October 1976 & JAES Vol. 25 Number 4 April 1977 pgs 170-177

A method for Measuring Transient Intermodulation Distortion by Eero Leinon, Matti Otala, John Curl AES preprint no 1185 presented at 55th convention, November 1976 and JAES Volume 25 Issue 4 pp. 170-177; April 1977 NOTE: This link takes you to a pdf

http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.394.9799&rep=rep1&type=pdf

Slewing induced distortion and its effect on audio amplifier performance - with correlated measurement /listening results, Jung, W. G. Stephens, M. L. and Todd, C. C., " AES Preprint 1252, AES Convention May 1977

Suppression of Slew-Rate and Transient Intermodulation Distortions in Audio Power Amplifiers by W. M. Leach JAES Vol. 25 No. 7/8 pp. 466-473 July/Aug 1977

Erratum: A Method for Measuring Transient Intermodulation Distortion JAES Vol. 25 Number 7/8 July/Aug 1977 pg 492

Correlation of Audio Distortion Specifications by Leinonen, E.; Otala, M J. Audio Eng. Soc., Vol. 26, Nos. 1/2, Jan./Feb, 1978

Letters To The Editor: Comments on "Suppression of Slew-Rate and Transient Intermodulation Distortions in Audio Power Amplifiers" by Peter Garde pgs 451, 452 Author’s Reply by William Marshall Leach pg 453, 454 JAES Vol. 26 Number 6 June 1978

Letters To The Editor: Comments on "A Method for Measuring Transient Intermodulation Distortion (TIM)" by Robert R. Cordell JAES Vol. 27 Number 4 April 1979 pg 295, Author’s Reply by Matti Otala, Eero Leinonen, and John Curl pg 296

Letters To The Editor: Comments on "Correlation of Audio Distortion Measurements" by Robert R. Cordell JAES Vol. 27 Number 4 April 1979 pg 297, Author’s Reply: Eero Leinonen and Matti Otala pg 298

IEEE Papers

Transient Distortion in Transistorized Audio Power Amplifiers by M. Otala IEEE Trans. on Audio and Electroacoustics, Vol. AU -18, Sept. 1970

The Theory of Transient Intermodulation Distortion by Matti Ottala, Eero Leinonen IEEE TRANSACTIONS ON ACOUSTICS, SPEECH, AND SIGNAL PROCESSING, VOL. ASSP-25, NO. 1, FEBRUARY 1977

Audibility of Transient Intermodulation Distortion by M. Petri-Larmi ; M. Otala ; E. Leinonen ; J. Lammasniemi ICASSP '78. IEEE International Conference on Acoustics, Speech, and Signal Processing April 10-12,1978

Magazine Articles

Transient IM Distortion by William Marshall Leach Audio Feb 1975 pg 34-36 pgs missing

An Overview of SID and TIM by Walter G. Jung, Mark L. Stephens, Craig C. Todd Audio June 1979 pgs 59, 60, 62, 64, 68, 70, 72

Another View Of TIM Part 1 by Robert R. Cordell Audio Feb 1980 pgs 38, 40, 42, 44, 46, 48, 49
http://www.cordellaudio.com/papers/another_view_of_tim.pdf

Another View Of TIM Part 1 by Robert R. Cordell Audio March 1980 pgs 39, 40, 42
http://www.cordellaudio.com/papers/another_view_of_tim_II.pdf

Sound Views: A talk with Dr. TIM (Matti Otala) by Robert Long High Fidelity Apr 1983 pg12

All About TIM Distortion by Len Feldman Radio Electronics June 1979 pgs 47-49

AMPLIFIERS: T.I.M. by John Curl Sound Advice Vol. 1 No. 4 pg 32 (see jpg in follow-up response by me)

Slewing Induced Distortion in Audio Amplifiers by Walt Jung TAA 1/1977 pgs 4-9, 20

Slewing Induced Distortion in Audio Amplifiers Part IIa; Phase 1: Total Harmonic Distortion Tests for SID by Walt Jung TAA 2/1977 pgs 22-24, 26, 28, 30, 31, 34, 36

Slewing Induced Distortion in Audio Amplifiers Part IIb: Phase 2: Two-Tone IM Tests for SID by Walt Jung TAA 2/1977 pgs 37-39

Slewing Induced Distortion: Part 3: Phase III Transient Intermodulation Tests for SID by Walt Jung, Mark L. Stephens, Craig Todd TAA 3/1977 pgs 21-26, 28, 57

Slewing Induced Distortion in Audio Amplifiers Part IV listening tests at last by Walter G. Jung TAA 4/1977 pgs 22-24, 26-28

Non-Linear Distortion in Audio Amplifiers by Matti Otala Wireless World Jan 1977 pgs 41-43


Harmon Kardon Citation XX White Paper

Soundcraftsmen A5002 Owner’s Manual see pages 18 and 19

Books

Electronic Measurements by U. A. Bakshi, A.V. Bakshi, K.A. Bakshi 1st edition 2008 ISBN: 9788184313918

https://books.google.com/books?id=-2tAxfbNBLYC&pg=SA4-PA29&lpg=SA4-PA29&dq=How+to+measure+Transient+Intermodulation+Distortion&source=bl&ots=rWjFNItLRR&sig=x3A22W9iiJxDQJ8aw_9Fh8bMdkg&hl=en&sa=X&ved=2ahUKEwip5JuJ3LveAhVEXawKHQiTCi44HhDoATAEegQIBBAB#v=onepage&q=How to measure Transient Intermodulation Distortion&f=false



NAB Engineering Handbook 110 & 11th editions section 8 & 10 state:

TIM distortion, is found only in amplifiers that utilize negative feedback. When this feedback is excessive, a fast-rising transient signal applied to the input of the amplifier can produce an internal overshoot that saturates the circuits in the amplifier.

The most popular procedure used to measure TIM distortion is called the sine-square wave method. The test signal employed uses a square wave to induce non-linearity in the test device by saturating the amplifier’s internal current, caused by its alternate rises and falls. Mixed with this square wave is a low-level, high-frequency sine wave, which is unrelated harmonically. In one definition, the frequency of the square wave is 3.18 kHz and that of the sine wave 15 kHz, where the peak-to-peak amplitude ratio of the former to the later is four to one [7]. Similar to the other IMD spectrum analyzer evaluation methods, the components present at the output can be combined to express a TIM distortion figure as a single percentage.

Other TIM measurement methods include a saw-tooth wave method that takes the amplifier slew ratio into account and a noise-square wave method, where the sine wave of the sine-square wave method is replaced by a narrow-band noise spectrum [8]

When filtering is used in IMD measurement, it is important to verify that in-band distortion components are not inadvertently removed. Also, sharp cut-off analog filter designs may produce overshoot components that could affect measurement results.

Ed

 

[laatsch55]

Thanks #Ed!!

 

[oldphaser]

I updated my original post with some new links.

 

[oldphaser]

AMPLIFIERS: T.I.M. by John Curl, Sound Advice magazine Vol. 1 No. 4 pg 32

Here are some photos of some T.I.M. measurements:
Electro Research, Audio Research D-100, Phase Linear 400 and Threshold

 

[BlazeES]

Thanks for posting all this. Not just a good cross-sectional of T.I.M. reference material, but WOW - these Audio magazine PDFs are a hoot to flip through.
There's T.I.M. mentioned in the product ads, Q&A section in addition to the actual article. And seeing J&R and Phase Linear 400 Series 2 ads is a mind blowing, blast-from-the past.

And to think that hitting 16, 17kHz on cassette decks was the height of achievement back then.

 

[laatsch55]

Ed, I see John Curl published A LOT!!

 

[oldphaser]

Ed, I see John Curl published A LOT!!

Lee,


I wasn't initially going to publish John's T.I.M. measurement results back when I first obtained a copy of this magazine because the results don't look so good in comparison to some of the other amplifiers. However, "it is what it is" as my son (with the BSEE) likes to say.

John was knee deep in S.I.D., T.I.M., I.M., T.H.D. and slew rate in the 70's. Hence, that is why I visited him last May and hope to again this year with even more questions.

By the way, not everybody bought into all of the T.I.M. stuff completely. However, when one is on the leading edge and discovering things for the first time, there will be others quick to find the faults. Bob Cordell had his opinions as is referenced in my initial post. Even though John and Bob had their differences, they are friends on Facebook. Likewise, Mark A. Davis (who worked for DBX and Dolby) had a debate with Matti Ottala at a Boston Audio Society meeting decades ago. There may even be an audio tape of that debate.