New questions about the Kartago.

Merle · « **on:** 27 May 2004, 10:00 pm »

OK, I've got the Kartago hooked up to the Rogue preamp. First, the good news. It is a great sounding amp. Now, my questions. I noticed the amp produces audible hum. Nothing that's enough to distract from the music but it's there all the same. Next, when I turn it on, I hear an "electrical" sound. Sort of like a "boing" sound. Goes away in about two or three seconds. Are the turn on sound and hum normal for this amp? Again, it makes great music but dead quite it's not. Last but not least, what the Hell is up with the blue laser beam on the front! I may go blind if I stare at it too long.

rosconey · « **Reply #1 on:** 27 May 2004, 10:07 pm »

the boing sound is the soft start circut-mine monos do it also-

hum -does it come from the speakers or the amp itself-is it plugged into a conditioner or power strip?

Ron D · « **Reply #2 on:** 27 May 2004, 10:27 pm »

Is the hum tied to the Rogue preamp? If the preamp is turned off can you still hear the hum?

Merle · « **Reply #3 on:** 28 May 2004, 01:41 am »

OK, both the Khartago [did I spell it right this time?

] and the Rogue are new to me, I just received both. I went back and checked. If only the preamp is on, no hum. If only the amp is on, no hum. Both turned on, hum. It's audible thru the speakers, not the amp itself. It's low level, if music is playing, I can't hear the hum. When no music is playing and I stand in front of the left speaker, I hear the hum. If I stand in front of the right speaker, I hear the hum as well as some high frequency hiss. Maybe the tubes in the preamp? Again, I should mention the combination sounds damm good, I believe they are both excellent amps, I'm getting fantastic music out of this combination. The Khartago is plugged directly into the wall socket using a Signal Audio power cord, the Rogue is plugged into a Monster Cable power strip. This combo replaced a Jolida tube integrated which was dead quite.

Marbles · « **Reply #4 on:** 28 May 2004, 02:07 am »

If you plug both into the same circuit it "should" get rid of the ground loop you are experiencing.

Ron D · « **Reply #5 on:** 28 May 2004, 06:06 am »

its probably the tubes that you are hearing. In my old set-up I remember that my Rogue 66 into my Bryston amp had a slight hum but as soon as any music started it was gone (or at least I could no longer hear it). I haven't had a source for a few weeks so my system is down. I may have something to play tomorrow and if so I'll fire it up and advise if I still get a hum with my bigger Rogue and bigger Bryston. The hiss on 1 channel may just a noisy tube which may indicate its coming to the end of its life. You could always e-mail the boys at Rogue and ask them. They are very helpful!

Marbles mentioned a "ground loop" hum and that typically is louder than what you are describing but could very well be the culprit. Try what he advises and let us know.

BikeWNC · « **Reply #6 on:** 28 May 2004, 07:27 pm »

I had a problem with hum when my tube preamp was directly above my amp in the rack. Moving the amp off to the side solved the problem.

Andy

speedcenter · « **Reply #7 on:** 28 May 2004, 08:50 pm »

my tube pre makes a lot of humming sounds until the tubes get warm. It's not coming from the amps. Also - you're really supposed to leave the power amps powered up all the time (at least my monos are supposed to be)

There is a slight 60hz hum in my speakers when I get very close to them with my ears, but that's only because I have the power amps virtually 5 inches behind the bass driver, so it picks up some of the transformer hum when I turn off the preamp (and the IC cable sturn into some sort of antenna), but it goes away completely once the preamp is powered up and warmed up.

Peter

proudx · « **Reply #8 on:** 29 May 2004, 09:15 pm »

I get the hum too. Could it be the power supply in the khartago unit is not as good of quality as the power supply in the startus unit?

Marbles · « **Reply #9 on:** 29 May 2004, 09:34 pm »

Quote from: proudx

I get the hum too. Could it be the power supply in the khartago unit is not as good of quality as the power supply in the startus unit?

One of the biggest differences between the Stratos and the Khartago is the power supply. The other major difference is the case.

The power transformers are both made by Plitron so even though they are different sizes, the quality should be about the same.

The hum is more likely a ground loop.

klaus@odyssey · « **Reply #10 on:** 29 May 2004, 10:46 pm »

One second here. Proudx , what you have i not a hum, but a hiss from a few inches away. What you essentially har is a 60 cycle buzz, which you can ind in over 90 % of systems and homes. There are tons of factors involved, and yes, true that the Plitrons in the Stratos are better transformers, of course, that's not the issue however.

An audible hum that you can crucify is a noise that you can clearly hear from whereverand that interferes with your listening.

Please be moe precise,

Klaus

proudx · « **Reply #11 on:** 30 May 2004, 12:16 am »

k, let me be more precise. There is audible hum from the listening position with the volumn turned up above 85db. With it lower than that there is only hum a few inches from the speakers and hiss as well. But never hiss from the listening position.

klaus@odyssey · « **Reply #12 on:** 30 May 2004, 01:17 am »

OK, David, call me asap, because that's not what you told me before, and that has to be rectified, because this "hum" is not acceptable,

Klaus

Merle · « **Reply #13 on:** 30 May 2004, 08:29 pm »

Just back home from a weekend away. The noise I was getting was tube related, both the hum and the hiss. I pulled the 12AU7's out of the Rogue and replaced them with some cheap stock Jolida tubes I had laying around. No more hum, no more hiss. I've got some better 12AU7's on order. One last thing. A couple of times I have also heard a "thumping" sound coming thru the speakers. Best was to describe it is it sounds like dropping the needle down on a record. I heard this once before I changed the tubes and once after, both times with the tuner playing. I just got home and played a couple of records, everything seems fine. I'm hoping the "thump" was something from the radio station and not a cap spitting. I'll know more as I get some more hours on the system. Great sounding set-up so far, damm musical!