Kora Amp and Preamp Repair

I'd have to be asking myself if there isn't some inherent fundamental design flaw that is causing the problems. I've read interviews with more than one designer/engineer that feels there are any number of poorly executed amp designs that are fundamentally flawed and subject to constant failure.

I can fix them. You can message me through Agon or contact me through the Alta Vista Audio website bigkidz email address. I am in Montville, NJ.

Your story reminds me of my AudioValve monos, made in Germany. They sounded wonderful when they worked, but ... poor reliability & costly repairs. Techs told me there were design issues, which I took that with a grain of salt, but several problems were due to just plain poor soldering. The amps were 11-12 yrs old and had cold solder joints here, there and everywhere. Fix one problem, another popped up somewhere else ... A moving target ...

Eventually I just cut my losses: 'got them repaired to spec, at high cost, sold them, and haven't looked back. Besides the money, the whole thing took up too much mental disc space. And there are many, many great sounding amps in the world ...

Your story reminds me of my AudioValve monos, made in Germany. They sounded wonderful when they worked, but ... poor reliability & costly repairs. Techs told me there were design issues. I took that with a grain of salt. But several issues were due to just plain poor soldering. The amps were 11-12 yrs old and had cold solder joints here, there and everywhere. Fix one problem, another popped up somewhere else ... A moving target ...

Eventually I just cut my losses: got them repaired to spec, at high cost, sold them, and haven't looked back. Besides the money, the whole thing took up too much mental disc space. And there are many, many great sounding amps in the world ...

I know this is an old thread but the record must be set straight. I stand corrected about Kora'a reliability. Kora is actually very reliable and resilient if owner/serviceman use it right.

SPECIFICALLY, ALL THOSE ISSUES WERE DUE TO THE WRONG TUBES BEING USED.

EL84M IS NOT THE SAME AS EL84. I REPEAT: EL84M IS NOT THE SAME AS EL84!

This will explain why Kora's preamp and DAC products (Eclipse, Hermes, Crescendo) are almost indestructible than their power products (Flash, Explorer, Cosmos, Galaxy, et al).

Kora's power amp products use EL84M which has a different bias. If you put regular EL84 (or the misleading EL84S) into Kora, you will risk damaging it! Fuses will blown, smoke may come out. You name it.

I finally realized the past malfunctioning Kora amps I encountered were all with EL84 from previous owners! To make it way worst, multiple repair shops tweaked the schematics to make them not blow up using EL84 --- of course that's not a true fix. Such wrongly repaired Kora become ticking time bomb.

It is very sad that the EL84M is grossly misunderstood, that some tube-rolling hungry owners may not bother to notice such critical difference, and some audio repair shops made the same wrong assumption and thus made things worst.

So do yourself s favor. If you are owner of Kora power amp and/or integrated amp products, please make sure you are using EL84M, not EL84.

Hope all of you enjoy the magical Kora sound as much as I do.