perceptible audio distortion

Actually it is a Bass Harmonica or "Bass Harp". See the links below for example.

and for a short sample of the sound, play the second song on this page.

Regards, Stephen D. Barnes

This varies widely with the type of distortion.

For "harminic distortion", this varies widely with which harmonics are formed and what frequency range is involved.

For a "1-size-fits-all" figure, a gentle nonlinearity that causes a sinewave to take on mostly second harmonic becomes audible around 1% THD as far as I have heard. A very sharp clipping becomes audible at much lower THD - maybe .2% on most voice and music signals.

Sinewaves with distortion generating mainly second harmonic will have audibility threshold of distortion vary widely with frequency. I have seen sources saying awfully high figures over 10% for very low audio frequencies.

Some frequencies of sine waves with sharp clipping may have distortion audible at under .1%.

If all distortion harmonics are ultrasonic, then "harmonic" distortion is inaudible except for any audible shift in the strength of the fundamental.

- Don Klipstein ( snipped-for-privacy@misty.com)

I have heard *very audible* crossover distortion with LM324. At least with National Semiconductor ones that Rat Shack sold in the early 1990's.

- Don Klipstein ( snipped-for-privacy@misty.com)

I have sometimes had TLO74 act up, probably more with capacitive loads such as shielded cables. Often a 150 or 330 ohm resistor between an op-amp output (with unity or otherwise low wired gain) and the conductor of a shielded cable works wonders!

I have had TLO84 behave better when TLO74 did not, though TLO74 was said to be less noisy, at least in the 1980's.

TLO7* and TLO8* have evolved over the decades. YMMV!!!

- Don Klipstein ( snipped-for-privacy@misty.com)

** The LM324 is no audio grade op-amp.

It was designed for single supply, low current applications - ie battery operation.

The output stage is a real odd ball - requiring direct coupling of the load ( no caps ) if x-over distortion is to be avoided.

See page 8 of

Even then, its overall poor performance counts it out, except maybe for guitar stomp boxes.

.... Phil

I was already aware of the LM324 having a high tendency to only behave well without crossover distortion in single-supply circuits. I wonder why you did not cite this along with ua709 before I mentioned it from actual experience working with it.

- Don Klipstein ( snipped-for-privacy@misty.com)

"Don Klipstein"

** You have it wrong yet again.

The x-over distortion issue is with cap coupling, not single supply.

** The OP said "some old opamps" - which the uA709 certainly is, having been around since 1965 and one of the first ever made. OTOH - the LM324 is relatively modern, having appeared in 1974 plus, as I said, not used in hi-fi audio.

FYI - the popular audio grade op-amp appeared as follows.

uA741 = 1968 LM101 = 1968 LM301A = 1969 uA748 = 1969 RC4558 = 1974 LF355 = 1975 TL081 = 1975 TL071 = 1976 NE5534 = 1977

Most are way older than folk imagine.

...... Phil

I always found BGW's easy to repair, mind you it was back in the eighties and were mainly 750's. ;)

les...

I didn't know such a thing even existed, but I knew it wasn't a sax.

...Jim Thompson

--
| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
  I\'ve finally figured out why Liberals have no sense of humor:
     All that mental constipation would make me cranky, too.

Motorola's were worse. So bad, in fact, that I put them on GenRad's "Do Not Purchase" list.

...Jim Thompson

--
| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

        Liberals are so cute.  Stupid as bricks, but cute.

TL084's were my "jelly-bean" OpAmp when I did discrete designs.

There is a trivial solution to driving capacitive loads. I believe I've addressed that issue on my website: SED section.

...Jim Thompson

--
| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

        Liberals are so cute.  Stupid as bricks, but cute.

First time I ever saw one I was front of house engineer at a major festival and a creole band was using one!

Regards, Stephen D, Barnes

This?

Michael

I know it's more than that, if for no other reason than I never used that one.

My memory is dim, but I know that it's at least the 741, possibly the LM358 and its relatives, and some other then-jelly-bean amplifiers from the early '80s.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

Yes.

...Jim Thompson

--
| James E.Thompson, P.E.                           |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |
             
  I\'ve finally figured out why Liberals have no sense of humor:
     All that mental constipation would make me cranky, too.

Back when I used to final test dispatch consoles for Motorola, I could perceive about .8% distortion at 1000 Hz. This was communications equipment and generally performed pretty well but if you over drove the mike or line inputs, the compressor would introduce the distortion. I never tried multi-tone distortion. I assume that the threshold would have been lower.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what\'s the reason?
For if it prosper, none dare call it treason."

"Follow The Money"  ;-P

** Nope - not a trace.

** Only if misused with cap coupling.

See page 8 of

** All the popular audio op-amps date from the 1970s.

uA741 = 1968 LM101 = 1968 LM301A = 1969 uA748 = 1969 RC4558 = 1974 LF355 = 1975 TL081 = 1975 TL071 = 1976 NE5534 = 1977

..... Phil

The issue is handling the current zero crossing - crossover distortion. I must not have elaborated enough to put coupling caps not preceded by resistors to ground into the discussion as examples of where the LM324 runs into crossover distortion.

Just a little older than I imagined - I thought the 741 came into use in the very early 1970's and TLO7* and TLO8* came into use in the very late

1970's.

Interesting history!

- Don Klipstein ( snipped-for-privacy@misty.com)

Aye. For more than 20 years i have told people that the speakers matter the most.