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Just upgraded my Integrated Amp - now here a HUM out of my LUMIN - HELP

I run two systems in my home - System one is in my family room - my old Krell 400 xi died last month. I replaced it with the new Krell Integrated amp the K300i - Everything is better - soundstage is larger - highs are clearer with no harshness, bass is amazing, and midrange vocals are so real Carly Simon vocals bring me to tears! My problem is I now have a very low level pulsating hum between tracks that I cannot eliminated. I have isolated this hum to my LUMIN when i input its feed into the Krell. The low level hum follows the RCA jacks as I move them from inputs S1 to S2 to S3 on the Krell. My DVD / CD player on this system does not have this issue - it is stone silent between tracks. The only ‘odd thing’ about my LUMIN RCA inputs is they are long - 15 feet. I have my LUMIN upstairs feeding my second system via the balanced outputs. This system runs with my older Krell S550i integrated amp. The sound is stone quiet between tracks - no HUM.

i am running the Krell K300i at a volume output of 65 ( volume runs from 0 to 100). I then control my actual volume via my I pad mini via the LUMIN app. My sound is amazing , but this HUM just bothers me. Do I need to ground the LUMIN D1? Both systems get their power via two separate FURMAN ELITE 15 Power Conditioners. I am out of options. Any help would be appreciated
tom8999
imhififan's avatar
imhififan
2,181 posts
 
My new RCA interconnects from Anticables from the LUMIN to the Krell k300i
My suggestion is try the Blue Jeans Cable LC-1 for better shielding.

https://www.bluejeanscable.com/store/audio/index.htm
flashbazbo's avatar
flashbazbo
12 posts
 
I’m a Chemist too! Good people...  I see two problems you have on the go. The 15 foot rca unbalanced is picking up noise as has been identified. That’s a long run for unbalanced rca cables in a possibly noise home environment. It seems you have minimized it as the other posts have suggested. Fluorescent lights and dimmers can be big contributors as mentioned. Keep the rca well away from ac cables. Well shielded cables can help as you have seen.  The second issue is “gain staging”. The lumin should be left a unity, or full volume in order to maximize the signal to noise ratio. Control you volume level at your preamp. This helps to further diminish the amount of noise in your signal.  The best would be to use the balanced Lumin outs for the long 15 foot run.
flashbazbo's avatar
flashbazbo
12 posts
 
I’m a Chemist too! Good people...  I see two problems you have on the go. The 15 foot rca unbalanced is picking up noise as has been identified. That’s a long run for unbalanced rca cables in a possibly noise home environment. It seems you have minimized it as the other posts have suggested. Fluorescent lights and dimmers can be big contributors as mentioned. Keep the rca well away from ac cables. Well shielded cables can help as you have seen.  The second issue is “gain staging”. The lumin should be left a unity, or full volume in order to maximize the signal to noise ratio. Control you volume level at your preamp. This helps to further diminish the amount of noise in your signal.  The best would be to use the balanced Lumin outs for the long 15 foot run.
edcyn
1,876 posts
 
I solved my phono hum problem with my Mytek Brooklyn Bridge.  A Mytek techie got a hold of me via email and walked me through a simple rerouting of a ground wire within the unit. 
tom8999 OP
153 posts
 
I wanted to give everyone an update on my situation with my HUM issue. It has now been minimized to a minor issue in my main system.

1) ground loop hum - I ran an extension cord to my upstairs system and put my LUMIN D1 on the same circuit. No improvement in hum reduction.

2) interference hum - I got the most improvement by moving all AC Cords away from my ICs. And I upgraded my 15 foot Audioquest IC to an Anticables 2.2 IC with extra shielding ($350). Dramatic hum reduction, and improvement in music detail from the LUMIN D1 the longer the new IC is in my system. Maxed my volume to 100 on the LUMIN D1 and control volume on the Krell - cannot stay in the room over 40 on the volume out of the preamp ( thanks flashbazbo).

3) DC offset hum - My LUMIN D1 came with a ‘Wall Wart ‘ External DC power supply. Just ordered an SBoost DC power supply from Upscale Audio ($399). - should have it installed this weekend. I am hoping to kill off the last of this HUM with the better DC power supply.

thanks for all the help!!
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