PLEASE ADVISE ME ...I bought Krell 400xi I am considering to hold it or give up and send back.. I notice 30Hz 4dB lower sinusoidal signal compare to 1 KHz and more on 20 and 15 Hz.
Channels difference at 1khz is at preamp section 0.0dB but on speakees posts 0.2dB but at 30 Hz both channel difference is 0.7 dB . power section non polar input 47uf capacitor right is 43uf left is 46uf . MAIN PROBLEM IS : ON OSCILOSCOP AT AVERAGE VOLUME LEVEL 1kHz sinusoidal wave is fine but below 100Hz looks like cut out tops and buttoms 30hz worse. . IS SOME SEMICONDUCTORS BROKEN OR INPUT NON POLAR CAPACITORS COUSE SINUSOIDAL WAVE TOPS AND BOTTOM WITH DOUBLE BUMPS PROBLEM? I AM NOT TOO EXPERIENCED WITH OSCILOSCOP . AMP SOUND WITHOUT STRONG BAS BUT JUST REGULAR.
Channels difference at 1khz is at preamp section 0.0dB but on speakees posts 0.2dB but at 30 Hz both channel difference is 0.7 dB . power section non polar input 47uf capacitor right is 43uf left is 46uf . MAIN PROBLEM IS : ON OSCILOSCOP AT AVERAGE VOLUME LEVEL 1kHz sinusoidal wave is fine but below 100Hz looks like cut out tops and buttoms 30hz worse. . IS SOME SEMICONDUCTORS BROKEN OR INPUT NON POLAR CAPACITORS COUSE SINUSOIDAL WAVE TOPS AND BOTTOM WITH DOUBLE BUMPS PROBLEM? I AM NOT TOO EXPERIENCED WITH OSCILOSCOP . AMP SOUND WITHOUT STRONG BAS BUT JUST REGULAR.
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Can't help out with the issue as I can't read the language but I recall wanting to buy one of these as the looks are gorgeous and the brand was supposedly legendary. Very excited to buy my first upper class amplifier and I could bring my own amplifier for comparison. It was then a considerable amount of money I had to pay. When we let warm up and compared both amplifiers both the owner, myself and a friend I brought noticed buying the 400Xi would make no sense at all. I could not believe my ears to be honest and the experience was a disappointment of the unexpected kind. I recall the owner getting a little angry when I politely asked if it had been modded or repaired.
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These toy integrated, smd-ed Krells always terrified me. As there is a VC section, one would first need to isolate this, just in case, and take measurements at the actual power amp input.
IMO the most likely culprit for the reduced output at LF would be a dried out NFB decoupling cap if such exists. Not even sure if there isn't a servo in this model.
Curiously, the reviewers of a presumably pristine sample had this to say
"I suspect that a certain number of consumers might misinterpret the accuracy of the 400xi's bass response for something else: excessive leanness."
Which i take as a polite way of saying "no bass to save it's life"
Jean-Paul, you are a horrible, horrible man
IMO the most likely culprit for the reduced output at LF would be a dried out NFB decoupling cap if such exists. Not even sure if there isn't a servo in this model.
Curiously, the reviewers of a presumably pristine sample had this to say
"I suspect that a certain number of consumers might misinterpret the accuracy of the 400xi's bass response for something else: excessive leanness."
Which i take as a polite way of saying "no bass to save it's life"
Jean-Paul, you are a horrible, horrible man
Can't help it. The ears work OK though. The way cheaper amplifier was much better in all aspects. Of course I forgot which brand and type that was but probably it was a compact DIY power amplifier with volume control. The friend I brought had nothing with HiFi but said openly that she could not understand why someone would replace something good for something less good for more money. Oops.
Since then I don't even look at Krell devices anymore. Probably the old stuff was good and they kept floating on that reputation.
Since then I don't even look at Krell devices anymore. Probably the old stuff was good and they kept floating on that reputation.
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I meassure preamp section output and Both channels plus and minus output are perfect ... but output measuure before and after output ressistors in Right Differencial plus is 20% louder than differencial minus! Simillar Left channel . Its mean its overloaded or bipolar feedback capacitors make short for frequencies below 100hz .... ???? please help me with this . I know how play original krell 400 with ts positive and negative aspects ....compare to mark lewinson 4808 but i need to fix mine.