perceptible audio distortion

[Eeyore]

For discrete circuits - where are the better amps? In Douglas Self's
books? Randy Slone's?

You won't find them easily but I did once produce a mosfet amp with 1 kHz THD of 0.0008% using an analyser whose residual was
0.0007%. Yes, that's below -100dB SINAD for both figures.. Remove the noise and god knows what it would have been. 0.0003% ?

At 350W into 8 ohms btw.

Plus it didn't suffer crossover issues.

Graham

 

[Eeyore]

We will call that your opinion. Tube amps are known for their low
damping factor since their loop gain is generally not as high as solid
state designs.

It's simple circuit analysis. A la Norton and Thevenin.

Yes, it freaked me when it was pointed out to me too.

Graham

 

[Eeyore]

Ironically, I get more bass from my tube amps than from a low-Z solid state
amp.

Yes, because of the lower damping where the output Z IS significiant. In the 50s
this was well known.

Graham

 

[Eeyore]

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!

Highly typical and audio pros have developed better ways still of dealing with
that problem over the years of varying levels of complexity. The simplest
involes 1 smallish value R and 1 tiny C and is generally the most popular.

Graham

 

[Phil Allison]

"Tim Wescott"

Phil Allison wrote:
"Glenn Gundlach"
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,

** Nope - not a trace.

possibly the LM358 and its relatives,

** Only if misused with cap coupling.

See page 8 of http://www.national.com/ds/LM/LM124.pdf

and some other then-jelly-bean amplifiers from the early '80s.

** 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

 

[Phil Allison]

<[email protected]>



** Piss off - you know nothing FUCKWIT TROLL




...... Phil

 

[[email protected]]

<[email protected]>

**  Piss off  -   you  know nothing  FUCKWIT  TROLL

.....  Phil

Have a nice day.

 

[Eeyore]

Yes.

With the likes of TL 07x op-amp amd mnny similar dopiloat audio op-amps types R1 is
not required and R2 can be lower. Look at some typical audio schematics.

Graham

 

[Don Klipstein]

"Don Klipstein"

** You have it wrong yet again.

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

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.

** 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.

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 ([email protected])

 

[Don Klipstein]

In <59a9c811-43d8-401c-804e-386dd9d12372@u36g2000pro.googlegroups.com>,

In <1453596a-a2d0-4a3f-86b8-d55c72e3b...@c65g2000hsa.googlegroups.com>,










  That only affects frequency response (to the extent loudspeaker
impedance varies with frequency) and resonant character (to the extent
tghe loudspeaker has resonances with impedance peaks/dips).

  Suppose amplifier A has a damping factor of 20, amplifier B has a
damping factor of 500, and you try each with a loudspeaker having a peak
impedance 5 times nominal and a dip impedance 75% of nominal.

  Amp A compared to Amp B accentuates frequency response at the
impedance peak by about .323 dB and de-accentuates frequency response at
the impedance dip by about .17 dB.  In the likely event that the impedance
peak in this case is resonant in character, Q of the resonance is
increased by about 3.79%.

  I would think that if one amp had THD .2% in higher order harmonics
and did so at frequencies as low as 500 Hz and the other had THD .02%,
then the harmonic distortion and intermodulation distortion would outweigh
effects of damping factor.

 - Don Klipstein ([email protected])

The ear is more sensitive to changes in amplitude for wideband signal
sources than say sine waves. You can demonstrate this with a pink
noise generator.

There have been double blind tests regarding if people can tell the
difference between amplifiers. [Double blind in the sense that the
person switching the amps is behind a curtain so that no visual clues
are given.] The tests were "same" or "different". Midband amplitudes
were made equal. The results were that some people can tell the
difference between amplifiers on a basis that exceeds statistical law
of chances.

You are describing how a frequency response irregularity is more audible
if at least 1/3 octave wide than if 1/12 octave wide, and how a frequency
response irregularity is more audible with broadband signal than with a
swept sinewave. This has nothing to do with "harmonic distortion" that
results from nonlinearities.

- Don Klipstein ([email protected])

 

[[email protected]]

In <59a9c811-43d8-401c-804e-386dd9d12...@u36g2000pro.googlegroups.com>,

The ear is more sensitive to changes in amplitude for wideband signal
sources than say sine waves. You can demonstrate this with a pink
noise generator.

There have been double blind tests regarding if people can tell the
difference between amplifiers. [Double blind in the sense that the
person switching the amps is behind a curtain so that no visual clues
are given.] The tests were "same" or "different". Midband amplitudes
were made equal. The results were that some people can tell the
difference between amplifiers on a basis that exceeds statistical law
of chances.

  You are describing how a frequency response irregularity is more audible
if at least 1/3 octave wide than if 1/12 octave wide, and how a frequency
response irregularity is more audible with broadband signal than with a
swept sinewave.  This has nothing to do with "harmonic distortion" that
results from nonlinearities.

 - Don Klipstein ([email protected])

No, but it does have to do with the damping factor effecting the
sound.

 

[JosephKK]

The largest contributor to measurable distortion in a playback system
is probably still the loudspeakers, which from memory can still run
consistently above 2% for a single harmonic.

RL

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

 

[Eeyore]

With the likes of TL 07x op-amp amd mnny similar dopiloat audio op-amps

Many similar bipolar.

Temp too hot for me @ 27C - I've just turned the a/c on. Bliss.

 

[Eeyore]

No, but it does have to do with the damping factor effecting the
sound.

How ?

Graham

 

[Eeyore]

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

Assuming everything else is up to scratch.

I believe ribbon (plus leaf) and electrostatic speakers provide the lowest
THD at typical listening levels.

Graham

 

[Phil Allison]

"Eeysore"

Many similar bipolar.

** Try again, wanker.

The TL07x series are " Bi-Fet " op-amps - having input junction FETs
fabricated on the same chip with BJT transistors to form a complete
operational amplifier.




...... Phil

 

[Fred Bartoli]

Tim Wescott a écrit :

I love reading the really serious-sounding "dip your stuff in LN2"
sites. For a while at least there was a site that sold specially
preselected, matched vacuum tubes that had been dipped.

I mean, it's just intuitively obvious that taking a tube that's been
stored for 40 years and dipping it in LN2 is going to make it sound
better, right?

Sure. Dipping a VT into LN2 is likely to make it *sound* (better?) for a
millisecond or two.

 

[Eeyore]

"Eeysore"

** Try again, wanker.

The TL07x series are " Bi-Fet " op-amps - having input junction FETs
fabricated on the same chip with BJT transistors to form a complete
operational amplifier.

I meant 'similar' only in the sense of op-amps specifically designed and
regularly used for for audio.

I would have though everyone knew the TL0xxs had jfet inputs.

My apologies for the confusion.

Graham

 

[[email protected]]

You won't find them easily but I did once produce a mosfet amp with 1 kHz THD of 0.0008% using an analyser whose residual was
0.0007%. Yes, that's below -100dB SINAD for both figures.. Remove the noise and god knows what it would have been. 0.0003% ?

At 350W into 8 ohms btw.

Plus it didn't suffer crossover issues.

Graham

With Lateral MOSFETS, right?

Michael

 

[[email protected]]

On Jul 26, 10:30 am, [email protected] wrote:


http://users.ece.gatech.edu/~mleach/lowtim/

G²

Thanks!

Michael