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Transient Intermodulation Distortion

post #1 of 5
Thread Starter 

So, I have been looking for good information about this, and haven't found any. 


Background, there is a company that has a patented amplification technology that allegedly eliminates this terrible problem with solid state amplifiers, IMD. Their tech is dubbed "Current amplification," and its elimination of IMD allegedly vastly improves the sound of treble compared to standard solid state amplifiers, alleged to have very harsh "metallic" treble. 


Of course, the usual purveyors of the audio world's many snake oils have claimed that they hear god through the amplification of currents instead of voltages (?I guess?). But that's to be expected, and an exaggeration on my part, but the amps do seem to be highly regarded by many sources that I don't trust.


But I like to learn myself, and so I started looking for papers on this transient intermodulation distortion thing, and it seems that it's definitely probably a problem with a lot of amplifiers that were made in the 70's, but the only current information that I found was in diy forums where people were trying to measure it, and others pointed back to the papers I had already found from the 70's. 


So what's the deal? Is this a real thing that plagues current amps? Is it cured in some other way on modern solid states (I feel like I read that feedback is used to reduce it in most amps) and does that cure come with no other ill effects? I am not going to drop my hard earned cash on something to try unless I feel like there is a reason to do so. I am leaning towards there not being a reason, but I try to keep a relatively open mind, but a semi-closed wallet. What does sound science have to say about this enthralling topic? 

post #2 of 5

This topic has been discussed recently in this thread.


In short, it is normally not an issue with competently designed amplifiers.

post #3 of 5
I've got the idea in my head that feedback generally worsens IMD. Please correct me if I'm wrong
post #4 of 5

Negative feedback reduces non-linear distortion, and that includes IMD (which is just the effect of non-linearity on harmonically not related tones).

post #5 of 5

the too simplified story - a feedback amp just needs to be "fast enough" to avoid TIM/SID - and any op amp recommended for audio that was designed in the past 20 years, built in modern full complementary semiconductor process is fast enough

Edited by jcx - 3/16/15 at 2:34pm
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