TIM generator

[darkfenriz]

Hi all

I would like to know your opinions.
I want to build a simple circuit for presentation what actually TIM in classic Otala meaning is and how it really sounds like and preferably I'd do it on line level.
My choice will probably be ua741 working at high output, like 15Vp-p swing followed with a voltage divider.
What do you think? Any ideas how to sex it up so that it generates TIM anyone can hear?

best regards
Adam

P.S. How about 4558?

 

[lineup]

TIM
transcendental interstage modulation ??
or what is it?

I am interested to hear also some TIM.
Don't know if anyone have heard it ....

I wonder how to create this ... hmmm
Another question is:
how high the level - before we can begin to notice TIM

As harmonic dist is probably possible to hear/notice at levels like 1-2%
and is said humans is more sensitive to TIM,
this means we could do with
a TIM-generator circuit capable to deliver at least 1% TIM distortion

I think PMA - Pavel Macura should know about this.
He has suggested some new Intermodulated signal for Audio Amplifier Testing

Regards
lineup

 

[darkfenriz]

Transient InterModulation Distortion

 

[darkfenriz]

Anyone?

 

[EchoWars]

Maybe TIM is a figment of someone's imagination after all...?

 

[Conrad Hoffman]

No idea how to do this, and as I understand TIM, if you limit the input signal bandwidth to the audio range, you'll never see it. I'm always amazed when people do square wave tests without considering the rise and fall times of the wave. A good square wave generator will put you way out into the RF with ease. Would one connect an RF generator to their amp? I have a very nice circuit that does nothing but set a specific slew rate- anything below that is untouched, anything above is slew limited, but that's not the same thing. On a similar note, I'd like to build an amplifier with adjustable IM distortion to see what it sounds like and how much is detectable. No idea how to do that either. It would also be useful to have an amplifier with adjustable THD, but with the distribution also adjustable, since the higher harmonics are supposed to be so audible. My guess is that all these things are best done with a DSP unless somebody here has some ideas in the analog domain.

 

[john curl]

Large amounts of TIM soften the sound. This has been done to great extent and accuracy at a Finnish hospital. I would have first thought that it would sound harsh, BUT actually what happens is that IM byproducts are produced that grow like grass and eventually take over the original signal. You can easily see this on a spectrum analyzer measuring TIM with a sine-square test signal.

 

[lumanauw]

http://www.diyaudio.com/forums/showthread.php?postid=355134#post355134
The sound? PRR said like splattering treble everywhere.

3,000pFd could turn everything to mush, treble splattering all over the audio band.

 

[OzMike]

I think TIM = transcendal Imaginary Mirage

If it takes such overcompensation to generate, it seems unlikely in anything with a reasonable slewing rate, one that's faster than the signal.

Mike

 

[darkfenriz]

Thanks David, that's exactly what I wanted.

TIM in classic Otala meaning

I meant that Daugherty, Otala, Curl and others observed and measured something that without doubt was a distortion not enough stessed before, I don't want to discus their reasoning and results and how real is it in modern designs.
Adam

 

[latala]

Just build a conventional phono premp split rail supplies then into a volume control followed bu a non inverting 20 db buffer amp
fit a couple of 741 and then listen you will hear all the tid that that you require !
Back in the 70,s when we paid about £5 for each 741 I built such a thing !! It measured very well but the sound was awful also if any one switched a light on or off or any other device the click was terrible in the sound system Also The unit was very prone to radio pickup and detection
This I believe was a classic case of
(1) TID
(2) slew rate limiting

Ps the same preamp was much improved years later when fitted with TL071
Regards Trevor