Krell running cool, not hot?

pyonc

Well-Known Member
Apr 23, 2016
8
0
106
Hi friends,

The other day I brought Krell KSA 50 back home after having had it checked and fixed by an experienced tech nearby. He said he diagnosed it and repaired a couple of parts including a small 'lytic cap', ruling all other functions and parts are okay. He said he "adjusted bias, along with load and audio test". Currently it's running bass in a bi-amp mode for my JBL 4343 system, producing a much more dynamic and deeper rich bass and larger sound stage than before. Now this is my question: as I understand, this Class A amp is supposed to run hot (or VERY HOT). But after even several hours of running, it still is running cool, not even lukewarm around the unit cover when I touch it. I checked the fan-cooler inside, and it's running all right while it's on. Is this running cool normal? If it's so, is it because of bias adjusting rather low or high done by the tech? I appreciate any comment or feedback from you who had a similar experience in advance.
 
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Edwards

New Member
Jul 14, 2016
3
1
0
Ksa-50 running cool

My experience with jbl is that it might be an easy load to drive.

I used to run a ksa-50mkii with infinity kappa 8s and after a full evening I could burn my hand on the top it got so hot. The same amp on jbl300's ran much cooler.

That said your krell (if biased properly) should run warm, even at idle. I think You need to have the amp re-biased.

Cheers, enjoy the amp.

Ed
 

pyonc

Well-Known Member
Apr 23, 2016
8
0
106
Thanks for your kind reply. Not that warm as I expected. I checked with Krell, and was told my Krell is running normal in its current condition.
 

clouseau1

Well-Known Member
Jun 28, 2017
16
0
108
Portugal
KRELL KPE REFERENCE PHONO
Hello to everybody.
Have recently came in possession of a Krell KPE Reference Phono w/separate P.S. and was surprised to see it runs almost cold.
Anyone in the past that had contact with a similar unit please kindly inform if is suposed to run cold, hot, or "in-between"?
Being familiar with some krell amps and preamps, they all run very hot.
The KPE Ref phono is playing well but, because I bought it in 2nd hand, cannot confirm anything. Have tried to search everywhere, but I think this forum seems the right place to get the answer.
Another question, this time about it´s impedance matching: There is a rail with extensive choices using dip-switches. In case all dips stay out, do we have 47K Ohm? or does it stay in 1K Ohm?
The "normal" KPE Phono manual refers that, if all dips are out, then the Impedance remains 47K Ohm.
Thanks in advance.
 
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pyonc

Well-Known Member
Apr 23, 2016
8
0
106
I heard from Krell that for my KRELL KSA50, only the area near fans gets hot, not the unit itself. I'm not sure of other Krells, though. You had better contact Krell directly on it.
 

clouseau1

Well-Known Member
Jun 28, 2017
16
0
108
Portugal
My experience with a KSA 50 mk2 dated '83 is actually driving old Quad 57 in my studio.
The silent fan, situated on top of the devices sink block is actually forcing the hot air to go down under the amp case, and not the opposite way to fill the inside area with unnecessary hot air.
I have donne the bias calibration to manufacturer´s spec 620mv but, that way, it gets damm hot and most important, didn´t like the sound. Too big ...So I reduced a little bit to 570mv and it sayed imho, just right.
Also payed attention to DC Offset at end.
 

pyonc

Well-Known Member
Apr 23, 2016
8
0
106
My experience with a KSA 50 mk2 dated '83 is actually driving old Quad 57 in my studio.
The silent fan, situated on top of the devices sink block is actually forcing the hot air to go down under the amp case, and not the opposite way to fill the inside area with unnecessary hot air.
I have donne the bias calibration to manufacturer´s spec 620mv but, that way, it gets damm hot and most important, didn´t like the sound. Too big ...So I reduced a little bit to 570mv and it sayed imho, just right.
Also payed attention to DC Offset at end.

Nice observation! I'm driving Krell KSA 50 for my JBL 4343 lows, which I'm satisfied with.
 

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