Zero distortion amplifier

[Circlotron]

https://www.google.com.au/search?q=quadramatic+410C+amplifier&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjc2LHagcPaAhUEerwKHchqDskQ_AUICygC&biw=1243&bih=969#imgrc=_

A bit of hyperbole going on. I think...

[BrianHG]

  They have a bass and treble knobs.  Isn't it the whole purpose of these knobs to distort the signal into a sweetened sound?

[BravoV]

Q.U.A.Dramatic ... (Q)uite (U)nconvincing (A)nd Dramatic

[Cyberdragon]

They have a bass and treble knobs.  Isn't it the whole purpose of these knobs to distort the signal into a sweetened sound?

No, bass and treble knobs are just frequency filters. They are not supposed to cause THD. You're thinking of the "English" knobs on guitar amps and such.

EDIT: Their claims are also probably BS. That amp is basic, it somehow has left and right treble, but not even a proper balance comtrol, just a switch! Why would you even want seperate tone controls for each channel, over a balance control which is more useful! They also have a "contour" switch. What the hell does that mean? That sounds like it would add distortion, which is fine, but don't give it a stupid name! My cheapo old transistor amp has more funtionality than that POS! Oh hell no, out of my sight with that rubbish before my eyes bleed!  

*burries himself in a box of tubes* "Wake me up when it's gone!"

[Refrigerator]

i bet it wouldn't go to 11 without distortion.

[BrianHG]

They have a bass and treble knobs.  Isn't it the whole purpose of these knobs to distort the signal into a sweetened sound?

No, bass and treble knobs are just frequency filters. They are not supposed to cause THD. You're thinking of the "English" knobs on guitar amps and such.

Tell me, if I feed the amp a perfect 40hz square wave and turn up or down the treble other than having it on a theoretical dead perfect flat setting, will the output not appear to be a distorted version of my perfect square wave source signal?  Note I understand what you are getting at, but when they say ABSOLUTE 0 distortion, they have to mean 0 distortion.  You cannot throw around a figure like that without being serious.  You need to get rid of all the bass, treble, and even balance BS and make a perfectly flat matched channel to channel gain amp with transformerless direct drive to the speaker terminals with proper negative feedback design to correct unusual speaker loads to achieve anywhere near such a claim.  Without a perfect corrected negative feedback at the speaker terminals, to have 0 distortion, wouldn't they have to have created an amp output driver stage with infinity current to deal with the varying impedances and currents over frequency range which come when driving a dynamic load like a speaker?

[hayatepilot]

Maybe the distortion was not measurable with common test equipment back in the day.
They probably couldn't measure below .1%
Then a sleazy marketing person came up with this BS claim of zero distortion.

[bd139]

Perhaps you had to plug it in and when you turn it on, the band arrives at your door. 

The irony of all this is the best recording I have of anything IMHO was recorded on a shitty Tascam minidisc deck using the lowest bidding everything between that and the instruments.

[Electro Detective]

Zero distortion is when the sound system is switched off, and the power cable unplugged from the wall   

[Refrigerator]

A simple audio cable also has 0% distortion.

[Brumby]

A simple audio cable also has 0% distortion.

Are you sure?

Zero has no wiggle room at all.  Even thermal noise from the wire's atomic structure would be outside the specification.

[thermistor-guy]

Quotes from the OP's attachments:

"absolute zero distortion"
"actually zero distortion"
"complete absence of any distortion"

I'm picturing a T-shirt. The front says: "The Stupid. It Burns." The back says: "Danger. Highly Flammable. Audiophool inside."

[Brumby]

"absolute zero distortion"

Yeah.  This one in particular gives no room for any tolerance.

[Cerebus]

I wonder how many people bothered to find out, before commenting, that this is a design (and presumably advert) from the early to mid 1960s?

By 1960's standards that "zero distortion" claim is close to pure "truth in advertising" compared to the claims that were made for many products. From what I can find out this was, for the day, a genuinely high quality bit of kit, and they probably couldn't measure the typical harmonic distortion with the instrumentation then generally available. Remember, the contemporary HP 204B sine wave oscillator was specified as harmonic distortion "< 1%".

[Circlotron]

Looks like some people didn't believe it back in the day either.

[Cerebus]

Is it just me, or does that "manufacturer's reply" have a passing similarity to the slightly better quality of marketing Chinglish?

[BrianHG]

Is it just me, or does that "manufacturer's reply" have a passing similarity to the slightly better quality of marketing Chinglish?

With one forgivable mistake, at the time, the manufacturer assumed that in outer space, there was an absolute 0 temperature.  We know better today.

[ebastler]

Is it just me, or does that "manufacturer's reply" have a passing similarity to the slightly better quality of marketing Chinglish?

Does the manufacturer’s reply essentially say „There is enough noise to make the distortion unmeasurable“?  ;-)

[Electro Detective]

Re: Zero distortion amplifier:

An empty amplifier chassis, parked on wet grass or moist ground, on a cloudy day   

Not sure what speaker cables will be compatible, an oxygen free variety perhaps

both must be equal length when stretched straight using a hired reference cable

I haven't quite worked out what the source interface will be, most likely the cheapest Audiophool thingie available secondhand,

still saving money for that, maybe I'll mortgage the trailer again... 





 

[Harb]

You didn't read the fineprint on the other side of the box "Actual Zero distortion was measured during a blackout on a wind free day"

[TimFox]

The manufacturer meant "unmeasureable distortion" but did not state that.
When my underlings tried to put "zero" in a specification for a non-integer parameter, I told them that "zero is a pious wish, not a spec".
During a similar era to the advertisements, I measured the distortion of a transistor RIAA preamplifier circuit using a decent Heathkit solid-state decade-switched generator (Bridged-Tee oscillator) and an old Hewlett Packard vacuum-tube distortion analyzer (Wien bridge to null the fundamental).  Connecting the generator directly to the analyzer gave approximately 0.1% THD, within spec for the Heathkit.  Connecting the generator through an attenuator to the preamplifier, which then drove the analyzer, gave approximately 0.07% THD.  Therefore, the amplifier must have had negative distortion.  Of course, the low-pass filtration of the RIAA network was responsible for cleaning up the output of the Heathkit somewhat.