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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
srafi OP
17 posts
 
The back of the amplifier looks similar but not exactly the same. It does not have a balanced input. Just 2 RCA jacks labelled inverted and non inverted. Is there a way I could link a picture?
I did leave the amps powered up from the back and just turn of the button on the front until it became direct. 
Thanks everyone for the comments. 
almarg's avatar
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almarg
9,670 posts
 
Jim (Jea48), some rear panel photos I found confirm that as Srafi said just above SOME versions of the KRS200 did not provide an XLR connector, but instead provided two RCA connectors, one designated as inverting and one as non-inverting. Lettering on the rear of those amps indicates that they are designed to be driven with a balanced pair of signals, so the "converter" Srafi referred to presumably just routes each of the two signals it receives via an XLR connector into a corresponding RCA plug.
Srafi 7-2-2016 2:22 am
...is there a way to get RCA to split the same way?
No, since the RCA outputs of the preamp do not provide both an inverted and a non-inverted signal.

What may be worth trying, though, is connecting the left channel RCA output of the preamp to the non-inverted input of the left channel amp, and connecting the right channel RCA output of the preamp to the non-inverted input of the right channel amp, and inserting an RCA shorting plug into the inverted input of both amps. Depending on the design of the amp that may work fine, although with a 6 db reduction in gain. Or, again depending on the specific design, it may result in a large reduction in power capability, as well as some degree of sonic compromise. Without being familiar with the design of the amp, my guess is that the odds are in favor of it working well, with just the gain reduction I mentioned.

The only other approach I can think of, besides having the preamp repaired, would be to connect the RCA outputs of the preamp to a pair of single-channel Jensen Transformers, one for each amp, that would convert each of the unbalanced signals from the preamp to a balanced pair of signals. It would provide those signals on an XLR connector, which would then be connected to the existing "converter."

Regards,
-- Al

floortoms1977
12 posts
 
Lose the KRC-3 and get a KRC-HR. 
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