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Krell Help

Hi Guys
A few questions regarding my Krell Power amp. 
I have a pair of Krell KRS 200 Monoblocks paired to the Krell KRC3 pre amp running B&W 800D. Due to some electric issue one XLR channel on the pre has stopped working though the RCA outputs work fine. The way my pre and power are wired at the moment is that the pre XLR out goes into a convertor into the back of the power. As I bought these used I never really gave this connection much thought, but at the back of the power this convertor becomes 2 RCA into the power. The RCA inputs on the power are labelled inverted/non inverted. 
Firstly I don't even understand how the connections on the power amp even work. Secondly is there a way to get RCA to split the same way? 
Also along the way due to the same electrical issue one of the monoblocks has now become direct in that the power button on the front of the amp does not work. The amp has to be shut of from the back main power button. When i do shut it from the back the amp will play music distorted for a few seconds as oppossed to the other one which shuts off when either the front or back power buttons are used. Any suggestions as to what could be causing this. The amp works absolutely fine and sounds fantastic. 
At the moment I am using a a ML 38s as a pre which was in another system. I have noticed that though the ML produces far less bass at similar volume the sound in my opinion is better and the imaging is just fantastic. I may just leave the ML in this system but would still like to get to the bottom of this issue. 

Thanks 

srafi

Showing 1 response by gs5556

gs5556
1,209 posts
 
I don't know the amplifier so am guessing the reason you hear music playing and fading out when the power is turned off is because there is a fault with the speaker protection circuit. The front button probably controls power to a relay that opens and closes contacts at the output from the speaker terminals. The main power switch breaks the mains power to the transformer, which also de-energizes the speaker protection relay. If this circuit is stuck in the closed position, the giant power supply capacitors maintain voltage for a few seconds after power is cut and you are hearing the fade out as they discharge. 

Even though the amp may sound fine, that protection circuit guards against DC offset, thermal overload and short circuits. Most important, it is the only thing protecting the output stage devices -- I doubt there are fuses protecting the output rails. It should be checked out by a tech. The amplifier is a 30-year old design and some things inside that amp are way past due for replacement.
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