Car Audio Central - Ultimate Car Audio Forum and Community

by **Jonathan** » Mon Apr 03, 2006 7:06 pm

I think there is a simple test in line for if amplifier distortion is a problem.

Ask said Audiophile to set the gain by ear, at the point where he hears audible distortion, be it a 0db reference tone, music, whatever he likes. Preferably on a test bench with a stable power supply to ensure accuracy (this would be for the benefit of the audiophile)

Once gain is set, connect the amplifier to an oscilloscope, at the same level, and observe the sine wave. I'll bet dollars to donuts the transistors are saturating, and that the distortion is much higher than it is thought to be.

by **GlassWolf** » Mon Apr 03, 2006 5:45 pm

nah. the power supply defines the dynamic headroom of an amp. A good amp has a PS capable of at least 3X the amp's rated output.
The THD more defines the tolerances and design of the amp itself, and how transparently the amp can produce the amplification.

by **smoker** » Mon Apr 03, 2006 3:03 pm

GlassWolf wrote:smoker, wasn't disputing you, just expounding on my previous statement so others would have a better idea of what we were talking about.
end result is THD ratings on amps are pointless by themselves, and not something to pick or pan an amplifier based upon solely when making a decision.
amplifier distortion, when the amp is used within it's limits, is inaudible.

i didnt get that feeling....i was just clarifying...

by **mikechec9** » Mon Apr 03, 2006 2:39 pm

Team AI wrote:So in basics I won't be doing my customers wrong if I offer them Interfire amplifiers as an money saving option and recommend they spend the extra they save on higher quality speakers when on a limited budget

A lesser quality amp does not suggest that it necessarily produces more distortion. There are plenty of amps that have identical power limits, but lesser build quality. These amps thus cost less money. Is there a bit of audible difference? No. But an amp like the Interfire (at least the 600 model) isn't one that I would suggest to my customers. Less money or not. It's not a decent sounding amp. The more it attemps to produce its rated power, the more it clips. The more it clips, the more distortion it produces and the worse the reproduction.

by **mikechec9** » Mon Apr 03, 2006 2:31 pm

GlassWolf wrote:end result is THD ratings on amps are pointless by themselves, and not something to pick or pan an amplifier based upon solely when making a decision.
amplifier distortion, when the amp is used within it's limits, is inaudible.

But Glass, doesn't the thd imply-to a degree-the limits of an amp. That is, how much an amp has to strain in order to produce said power. An amp with a significantly lower thd at an identical rms suggests greater capability to produce that power. Regardless of how audible the distortion is or isn't. Correct or no?

by **Team AI** » Mon Apr 03, 2006 2:18 pm

So in basics I won't be doing my customers wrong if I offer them Interfire amplifiers as an money saving option and recommend they spend the extra they save on higher quality speakers when on a limited budget

by **GlassWolf** » Mon Apr 03, 2006 2:04 pm

smoker, wasn't disputing you, just expounding on my previous statement so others would have a better idea of what we were talking about.

end result is THD ratings on amps are pointless by themselves, and not something to pick or pan an amplifier based upon solely when making a decision.
amplifier distortion, when the amp is used within it's limits, is inaudible.

by **mikechec9** » Mon Apr 03, 2006 1:56 pm

GlassWolf wrote:depends on the type of distortion. intermodulation distortion sounds like unadulterated ass. so do even ordered harmonics, but look at a tube amp.. running 10%THD of odd ordered and people call them desireable and "warm."

Jonathan wrote:Fully agree. Most of the "high end" $12,000 8W tube amps are made to cater to corrupted taste. Add the PITA of rebiasing, tube replacement, and degradation of performance over time (until said tube replacement and rebiasing), I see no need for tubes to exist anymore. Unless you're really all that worried about the occasional EMP striking your beloved amplifier.

Yop. I love how The Audio Critic breaks down his disdain for the rave about tube amps. I mean, to each his own. Everyone has their own sets of ears, but I just enjoyed his method of elaborating on the

that tube amps have received over the years. Pretty similar actually:

http://www.theaudiocritic.com/downloads/article_1.pdf

*edit* That would be lie #2, by the way.

by **Team AI** » Mon Apr 03, 2006 1:22 pm

well I'm hoping to start doing business out of it within the next couple of weeks, my wife is mixed on car audio, she doesn't share my passion for it but after hearing her favorite song in my car she demanded some "Boom Boom" in her car so when I get my truck done I'm going to start working on and SQ system for hers, I think the car would be an awsome sq car and with the variety of music she listens too and the volume range she usually has it in I think she would appreciate it a lot more, of course anything that involves tricking out Tibby she is down for :P
This is Tibby btw.

by **High Society** » Mon Apr 03, 2006 1:11 pm

How long till the shop opens up? What does the wife think about car audio.........I would guess she hates it lol.

Car Audio Central - Ultimate Car Audio Forum and Community

Starting a Shop, Need some advice.

Post a reply

Expand view Topic review: Starting a Shop, Need some advice.