On the audio WAV I have extracted here, there is a long section
of distorted "flapping" in the background during narration and
commenting. I haven't been able to get rid of it using more
modern programs without destroying the entire bass of the clip.
Basically, converting it to a mono radio or telephone frequency
is the only way. Does anyone know what this happens or what I
could do to remove this distortion?

Ben Markson wrote:

On the audio WAV I have extracted here, there is a long section
of distorted "flapping" in the background during narration and
commenting. I haven't been able to get rid of it using more
modern programs without destroying the entire bass of the clip.
Basically, converting it to a mono radio or telephone frequency
is the only way. Does anyone know what this happens or what I
could do to remove this distortion?

May I suggest you start at the beginning ? No-one's heard your wav
file.

What happened ?

What do you mean by a " more modern program " etc....... ?

Graham

"Ben Markson" wrote in message
news:IC_Cf.2764$J81.1911@trndny01...
On the audio WAV I have extracted here, there is a long section
of distorted "flapping" in the background during narration and
commenting. I haven't been able to get rid of it using more
modern programs without destroying the entire bass of the clip.
Basically, converting it to a mono radio or telephone frequency
is the only way. Does anyone know what this happens or what I
could do to remove this distortion?

=========================================
Could it be "motor-boating" in the audio amplifier?

Motor boating is due to very low frequency positive feedback between
output and low-level amplifier stages via the DC power supply. It
results in a sub-audio frequency oscillation which cannot be heard
from the loudspeaker but amplifier gain varies in sympathy with the
oscillation frequency.

It can be remedied by improving decoupling of the low-level stages
from the power supply.

But it may be a defect in the DC power unit which has an abnormally
high internal impedance. This allows the power amplifier stage to
develop signal-related voltages across the power supply which are fed
back to earlier amplifier stages. Or it may be fed back to the other
half of the sterio amplifier which shares the same DC power supply.

This is a case of very careful listening with a pair of ears, and an
understanding of what might be going on, being a better diagnostic
tool than a whole collection of electrical measuring instruments.

On the other hand, the distortion may be nothing to do with motor
boating. Describe the symptoms more carefully.

You could connect a 10,000 or 20,000 microfarads capacitor across the
DC power supply and see what happens.

Has the distortion always been there, or did it suddenly appear?
----
Reg.

Reg Edwards wrote:

"Ben Markson" wrote in message
news:IC_Cf.2764$J81.1911@trndny01...
On the audio WAV I have extracted here, there is a long section
of distorted "flapping" in the background during narration and
commenting. I haven't been able to get rid of it using more
modern programs without destroying the entire bass of the clip.
Basically, converting it to a mono radio or telephone frequency
is the only way. Does anyone know what this happens or what I
could do to remove this distortion?

=========================================
Could it be "motor-boating" in the audio amplifier?

You reckon he has a valve/toob amplifier ?

Graham

You reckon he has a valve/toob amplifier ?

=======================================

Motor boating can occur just as easily in transistor amplifiers.

Reg Edwards wrote:

You reckon he has a valve/toob amplifier ?

=======================================

Motor boating can occur just as easily in transistor amplifiers.

Not typically. Few transistor amplifers are designed that badly (
especially wrt a single supply rail ).

Graham

Not typically. Few transistor amplifers are designed that badly (
especially wrt a single supply rail ).

Graham
=========================================
On the other hand, few 'toob' amplifiers are designed that badly.
Like transistor amplifiers they should never get out of the
laboratory.
----
Reg.

Reg Edwards wrote:

Not typically. Few transistor amplifers are designed that badly (
especially wrt a single supply rail ).

Graham

=========================================
On the other hand, few 'toob' amplifiers are designed that badly.
Like transistor amplifiers they should never get out of the
laboratory.

How many amps are designed so that they don't behave badly with failed
components?
The only motor-boating amp I heard was a Grundig in nineteen
sixty-something.
When it was repaired (not redesigned) it worked again.

--
Eiron

I have no spirit to play with you; your dearth of judgment renders you
tedious - Ben Jonson.

In sci.electronics.design Pooh Bear wrote:


Reg Edwards wrote:

You reckon he has a valve/toob amplifier ?

=======================================

Motor boating can occur just as easily in transistor amplifiers.

Not typically. Few transistor amplifers are designed that badly (
especially wrt a single supply rail ).

I've got about 3 seperate brands of transitro radio that will motorboatr
at low battery voltage.

"Ben Markson" wrote in
message news:IC_Cf.2764$J81.1911@trndny01

On the audio WAV I have extracted here, there is a long
section of distorted "flapping" in the background during
narration and commenting. I haven't been able to get rid
of it using more modern programs without destroying the
entire bass of the clip. Basically, converting it to a
mono radio or telephone frequency is the only way. Does
anyone know what this happens or what I could do to
remove this distortion?

The flapping sound might be a subsonic tone that was use for remote
controlling some equipment.

You can get rid of some of it with a sharp cut-off high pass filter, but if
it was distorted along the way, the distortion overlays your narration and
is harder to get rid of.

You might be able to get rid of the harmonics with a bank of notch filters.

Adobe Audition has a lot of good tools for dealing with situationsl ike
this.

Ian Stirling wrote:

In sci.electronics.design Pooh Bear wrote:


Reg Edwards wrote:

You reckon he has a valve/toob amplifier ?

=======================================

Motor boating can occur just as easily in transistor amplifiers.

Not typically. Few transistor amplifers are designed that badly (
especially wrt a single supply rail ).

I've got about 3 seperate brands of transitro radio that will motorboatr
at low battery voltage.

I reckon the 'transistor radio' is hardly the pinnacle of modern design !

I imagine that's where the battery goes hi-Z.

Graham

In article ,
Reg Edwards g4fgq,regp@ZZZbtinternet,com wrote:

You reckon he has a valve/toob amplifier ?

Motor boating can occur just as easily in transistor amplifiers.

It is very popular in old 1970s gear... electrolytic caps dry out and
the bass poles and zeros start moving around. Sometimes they wind up
in bad places.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

"Ben Markson" wrote in news:IC_Cf.2764
$J81.1911@trndny01:

On the audio WAV I have extracted here, there is a long section
of distorted "flapping" in the background during narration and
commenting. I haven't been able to get rid of it using more
modern programs without destroying the entire bass of the clip.
Basically, converting it to a mono radio or telephone frequency
is the only way. Does anyone know what this happens or what I
could do to remove this distortion?

Simple noise at about 120 Hz and below can sound like that if it's loud
enough. Sounds like the buffeting you hear when driving in a car at high
speed with the windows open.

The only solution I've found is to filter it out anytime the bass isn't
covering it (i.e. during narration and commenting). Tedious but effective.

In sci.electronics.design Pooh Bear wrote:


Ian Stirling wrote:

In sci.electronics.design Pooh Bear wrote:


Reg Edwards wrote:

You reckon he has a valve/toob amplifier ?

=======================================

Motor boating can occur just as easily in transistor amplifiers.

Not typically. Few transistor amplifers are designed that badly (
especially wrt a single supply rail ).

I've got about 3 seperate brands of transitro radio that will motorboatr
at low battery voltage.

I reckon the 'transistor radio' is hardly the pinnacle of modern design !

I'm shocked.
Shocked I tell you.
A radio I bought for the price of 4 loaves of bread being not the
pinnacle of modern design, it's going back

I imagine that's where the battery goes hi-Z.

Basically, I'd imagine.

In article ,
Pooh Bear wrote:
[...]
Not typically. Few transistor amplifers are designed that badly (
especially wrt a single supply rail ).

Do you mean the number of designs is low or the number of units produced
is low? I can believe that very few crappy designs get generated but not
that they wouldn't be mass produced if they cost less.

The AM-FM radio in my 1977 Dodge Omni was mass produced and was a good
argument against the quality of transistor amplifiers, transistor radios,
plastic knobs, sheet metal screws, angle brackets, connectors, chassis
bending and cars that transistor stuff can be bolted into.



--
--
forging knowledge

Ken Smith wrote:

In article ,
Pooh Bear wrote:
[...]

Not typically. Few transistor amplifers are designed that badly (
especially wrt a single supply rail ).


Do you mean the number of designs is low or the number of units produced
is low? I can believe that very few crappy designs get generated but not
that they wouldn't be mass produced if they cost less.

The AM-FM radio in my 1977 Dodge Omni was mass produced and was a good
argument against the quality of transistor amplifiers, transistor radios,
plastic knobs, sheet metal screws, angle brackets, connectors, chassis
bending and cars that transistor stuff can be bolted into.




Yet there was, inexplicably, a Carroll Shelby Omni...

--
Les Cargill

On Sun, 29 Jan 2006 08:00:40 GMT, "Ben Markson"
wrote:

On the audio WAV I have extracted here, there is a long section
of distorted "flapping" in the background during narration and
commenting. I haven't been able to get rid of it using more
modern programs without destroying the entire bass of the clip.
Basically, converting it to a mono radio or telephone frequency
is the only way. Does anyone know what this happens or what I
could do to remove this distortion?

Let's hear it then. Else we're just guessing. Post a sample on a
web page.

Hard to tell without listening to it. One possibility is your
recording device has some sort of automatic level control, which when
hit with speech is bringing up the background noise level between
words. Once this has been recorded there's no easy way to get it out.