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Discussion Starter · #1 ·
I've got a strange problem that I thought I'd post here to see if anyone has encountered anything similar. My music system consists of a Krell KAV-300i integrated amplifier driving Legacy Focus speakers. I use this system also as part of a movie system. I take the main L/R pre-outs from my AVR and run them into the "S-3" input, or pre-ins on the Krell. This S-3 input is designed for use with a separate AV processor, and is disconnected from the pre-amp circuitry of the Krell.


I utilized a Sherwood R-945 receiver for years with this setup without issue. I just replaced the Sherwood with, first a Sony STR-DA4300ES, and then a Denon 3808 CI. With this setup, I get a loud, line level popping noise through the speakers driven by the Krell at irregular intervals, generally every 3-7 seconds. The noise sounds to me like some sort of an electrical discharge, but I'm just guessing.


I went through 2 versions of the Sony AVR as well as the Denon before pulling the Krell out of the system. The service guys at Krell have never heard of such a problem, which makes me reluctant to just send the 300i back to them for inspection. Has anyone ever encountered a similar problem, with any amp and pre-amp? Any ideas or suggestions would be appreciated.
 

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Is it possible that one of the interconnects has become damaged? It sounds like you have a short.


Lee
 

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The 300i has some quirky design to it. We had a customer who had similar problems and he finally sold his and another one traded his in because of sensitivity to ground loop issues. They're very finicky about system context for some reason. The 400 versions are supposed to be better in this regard, but it might just not be a good fit. As is many times the case, the entry product doesn't live up to the name attached, but sells anyway. Maybe just a good stereo amp instead? Or, something like the NAD Masters M3 which works very well and also has theater bypass circuitry.


Of course, as Lee suggests, there could be just a problem with an input that is fixable. BUT, if it works out of this context, I'd say sell it and find something that works better in the context you have.
 

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Discussion Starter · #4 ·
I've changed out interconnects without solving the problem. And as suggested, it may be just some quirk with the Krell. I can drive my main L/R speakers with the Denon and it sounds reasonable, but nothing like it did with the Krell. Of course, I may have no choice.
 

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Without meaning to cause you any alarm, the KAV 300i is very sensitive to multiple cable changes on their RCA input connectors. I know this because I literally saw this first hand when I borrowed and demoed the unit from my favorite high-end A/V shop before I purchased one years ago.



In other words, the RCA connectors are not the same ones they use in the higher end amps. To break it down even further, they're cheap! LOL!



I was using a locking interconnect cable at the time of the demo and to my surprise, I literally pulled an RCA cap out of the unit when exchanging cables. I was able to get the cap back on, but the sound was not the same after that. When I returned the unit back to the dealer and told him what happened, he stated that he had seen and known about the issue. He stated that the unit had been sent back to Krell a few times because of the mulitiple issues they were having with using the cheaper caps.


From your message, I can see that you have changed or swapped cables a few times. It is possible that one of the S-3 RCA connectors is bad. You might want to take the cover off of the unit to try to verify. If the connector is bad, then you might consider taking the unit to your dealer so that they can send it to Krell for repair.


My unit is still going strong after all these years. However, I am very careful whenever I have to make a cable change.
Good luck!
 

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Discussion Starter · #6 ·
An unexpected solution to this problem appeared that I thought I'd post for anyone who followed this thread. Many years ago I purchased a Legacy Steradian processor (a "sophisticated" bass control) for a set of Legacy Classics. I never used it with the Focus. This morning I inserted this processor between the Denon AVR and the Krell and that solved the problem - no clicks and pops coming out of the speakers. As was suggested, the Krell seems sensitive to the components it is matched with. It wasn't happy with the pre-out signal from the Denon or Sony AVR, but seems to have no problem with that same pre-out signal run through the processor.
 

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Why not use balanced connectors?
 

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Quote:
Originally Posted by thebland /forum/post/15647774


Why not use balanced connectors?

Maybe because the Denon 3805 doesn't have balanced outputs (nor any other receiver I'm aware of) have balanced outputs.
 

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Quote:
Originally Posted by John Kotches /forum/post/15651830


Maybe because the Denon 3805 doesn't have balanced outputs (nor any other receiver I'm aware of) have balanced outputs.

Ah... I don't follow receivers so much.. No receiver with balanced, eh?? Didn't Lexicon make one with balanced?
 

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Discussion Starter · #10 ·
This is beyond weird. Fired up the system and popping noise is back, however it comes and goes. Watched a segment of 60 Minutes with the audio run through the HiFi system and during the first segment the speakers were popping. During the second segment the speakers were dead quiet - no popping noise. During the third segment the popping noise was back. That makes no sense to me - all three segments were just dialog. Watched a concert with no popping noise. Put on a second concert with loud popping noises. The audio gods are playing games with me.
 

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If its a bad connection, try RCA to BALANCED connectors... about $7 at Guitar Center... Just bypass the RCA inputs as that seems to be a known issue.
 

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Quote:
Originally Posted by thebland /forum/post/15653765


Ah... I don't follow receivers so much.. No receiver with balanced, eh?? Didn't Lexicon make one with balanced?

The only Lexicon receiver I'm familiar with is the RV-5, which doesn't have any balanced I/O.
 

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Popping sounds usually imply DC. If you had a DC voltage on the interface and it was somehow periodically discharging, it could cause that type of sound.


ps - electrostatic discharge into a high impedance connection can also cause the sound.
 

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Discussion Starter · #15 ·
"Popping sounds usually imply DC. If you had a DC voltage on the interface and it was somehow periodically discharging, it could cause that type of sound.


ps - electrostatic discharge into a high impedance connection can also cause the sound."


Could you expand on those comments? I'd really like to make this set-up work and I'm willing to try some additional experimenting. One comment was to use an RCA to XLR connector and use the balanced inputs on the Krell. The problem there is the balanced inputs are still connected to the pre-amp section of the Krell. One thought is to go RCA to XLR from the AVR to the processor, and then XLR back to RCA from the processor to the Krell. I don't know if changing the signal from unbalanced to balanced through a portion of the chain would interrupt this electrical discharge - I just don't know enough about the problem.
 

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Are you hearing popping or a short burst of 60 Hz (more like a blat than a pop)? Also, are you feeding the Krell digital (PCM) or analog signal?
 

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Discussion Starter · #17 ·
The sound is more like popping and isn't always the same. Sometimes its a solitary pop, and other times its a series of pops. The Krell is connected with analog connectors, however the source is usually a digital signal. However the sound occurs with no source selected and no signal being sent - just the AVR and the Krell powered on with all the source components powered off.
 

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do you have a cable tv box connected to your AVR? If so pull the coax cable feed from the cable company out of the box. see if that helps...


does the krell have a 3 prong power plug? If so try a cheater 2 prong adapter plug. Temporarily only.. but just to see if the poping goes away.


Sounds like it has a problem but first troubleshoot to see if you can determine a source of the issue.
 

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Interesting problem. Perhaps AC line transients of some sort are being injected into the cable shield (signal ground) from your source equipment into the Krell's signal ground. Transients could originate from an AC line input filter in your source equipment. Your old Sherwood probably didn't use one.
 
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