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Topic: Hum in my rack system. |
Jack Ritter
From:
Enid, Oklahoma, USA
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Posted 15 May 2019 7:48 am |
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Any of you know of a place you would recomend to get it checked out in this area or 100 miles or so from Enid, Okla? Already had the Furlong looked at here and they did not find any problem. So I figure it must be in the Rev or the TC M300. Checked all the cables and no problems. Never been dropped. Tried my system thru my n-112 and still had a hum.
Would appreciate any help. I am not the smartest guy on electronics. Thanks, Jack
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Zum D10 8x5,rev pre-amp, TC M300, Split 12, n-112, IZZY, Hilton vp, Geo L, BJS Hughey, Live Steel |
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Ray DeVoe
From:
Hudson, FL
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Posted 15 May 2019 8:05 am Hum
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Just some thoughts.
Totally eliminate the TC Electronics effects unit from the circuit.
That will tell you one way or the other if the effects unit is the source of the problem. Do you run the effects through the revelation loop or in-between the preamp and Furlong?
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How high are you setting your gain / volume control on the Furlong. If it is set too high, you will get a lot of white noise. I usually run my Furlong gain just above 1/2 way. That setting depends on how hot of a signal you are sending from your preamp.
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Did you try eliminating the rack altogether and playing through the Nashville 112 to see if you still have the hum. If you still have the hum, then its from something else in your system.
I hope this helps
RD
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Zum SD 10 Hybrid, Zum D 10 Hybrid, Emmons SD 10 P.P.
SMS: Revelation & Classic Preamps: Furlong 12" Splits.
Webb 15" Splits: Telonics 500 C: Head and 12" cabinet:
Last edited by Ray DeVoe on 15 May 2019 12:15 pm; edited 2 times in total |
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Ken Metcalf
From:
San Antonio Texas USA
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Posted 15 May 2019 11:29 am
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I had this prob with a Revelation and rack power amp
Had to connect to power amp with TRS or mic cables.
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MSA 12 String E9th/B6th Universal.
Little Walter PF-89.
Bunch of stomp boxes |
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Jack Stoner
From:
Kansas City, MO
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Posted 15 May 2019 12:05 pm
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A common problem, whether its your problem or not, is one unit can be causing it with the metal rack rails and the different devices "rack ears" screwed to the metal rack.
Remove all the rack ear screws. Then, with it all powered on and connected, lift one device so its not touching the rack rails at the rack ears and also make sure the nothing is touching and see if the hum goes away. If not, set that device back down and lift one of the others. Try it with each unit and see if one of them is causing it. If it is one of the units "feeding back" through the rack ears, you can use nylon (Non metallic) washers to isolate each device from the rack rails and even use nylon screws instead of the metal rack screws. There is also commercially sold "Humfrees" for isolating. |
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Jack Ritter
From:
Enid, Oklahoma, USA
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Posted 15 May 2019 5:28 pm
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Thanks for your replies. Gonna do some more checking.
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Zum D10 8x5,rev pre-amp, TC M300, Split 12, n-112, IZZY, Hilton vp, Geo L, BJS Hughey, Live Steel |
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Len Amaral
From:
Rehoboth,MA 02769
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Posted 15 May 2019 5:57 pm
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Jack is on target with the rack rails causing a ground loop. There use to be a ground insulation kit the isolated the rack effects from the rails.
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I survived the sixties! |
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Michael Hill
From:
Arizona, USA
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Posted 15 May 2019 8:06 pm
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What's the power situation? If you have more than 1 wall outlet in use it can cause this type of problem. If you have a single wall outlet feeding everything in the rack, that would be best.
If all else fails, Radial makes all kinds of direct boxes / isolation boxes with ground lifts. A ground lift between the 2 offending pieces of equipment usually works. |
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Godfrey Arthur
From:
3rd Rock
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Posted 15 May 2019 10:13 pm
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Ground loop, sounds like. Jack's (Stoner) idea can be expanded to Humfrees:
https://www.sweetwater.com/store/detail/IsoTabs--humfrees-rack-isolation-tabs
If not, one transformer inside one of the rack units does not like proximity to another.
May have to juggle the positions of them until you source the problem.
OR..it may need as Ken alluded to, use of TRS.
Rane has a ground solution system using cables and lifting the ground on one end of the cable for their rack units.
May check their POV on grounding.
http://www.rane.com/note151.html
Also Michael's approach of too many paths to ground with the multiple AC outlet connections instead of all units [including your amp] through one AC outlet source, could be an issue causing the ground loop.
I would start with checking all your rig's AC is sourced from one outlet first before attempting the other solutions.
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ShoBud The Pro 1
YES it's my REAL NAME!
Ezekiel 33:7 |
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Dennis Detweiler
From:
Solon, Iowa, US
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Posted 16 May 2019 5:36 am
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I have to use a two prong adapter on my M350 to eliminate the hum in my rack. The Rev and power amp stay with their normal 3 prong plug.
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1976 Birdseye U-12 MSA with Telonics 427 pickup, 1975 Birdseye U-12 MSA with Telonics X-12 pickup, Revelation preamp, Carbon Copy Delay and Hall Of Fame Reverb, Crown XLS 1002, 2- 15" Eminence Wheelhouse speakers, ShoBud Pedal, Effects Pedals. 1949 Epiphone D-8. |
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Ken Metcalf
From:
San Antonio Texas USA
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Posted 16 May 2019 6:34 am
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I might add that I tried the humfree tabs first and they did not help in my case.
Connecting from Rev to the power amp with TRS or mic cables did the trick.
_________________
MSA 12 String E9th/B6th Universal.
Little Walter PF-89.
Bunch of stomp boxes |
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Michael Hartz
From:
Decorah, Iowa, USA
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Posted 18 May 2019 6:30 am
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| Do a forum search for “wall outlet hum,” in it I posted instructions and a diagram on how to build an outlet box with hum X or Ebtech hum eliminator circuit in it. It will get rid of your hum without causing any safety issues by lifting any grounds. Minimal soldering skills required. |
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Jack Stoner
From:
Kansas City, MO
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Posted 18 May 2019 7:40 am
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| Quote: |
I would start with checking all your rig's AC is sourced from one outlet first before attempting the other solutions.
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Whether everything is powered from one outlet or separate doesn't make a difference. There can still be ground loop hum either way. |
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Michael Hill
From:
Arizona, USA
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Posted 19 May 2019 10:24 am
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Using multiple outlets is the most common source of a ground loop hum.
If a balanced cable fixes your problem, your old cables were picking up noise from somewhere. A balanced cable makes no difference for a ground loop hum. |
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Jack Ritter
From:
Enid, Oklahoma, USA
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Posted 21 May 2019 10:13 am I think we got it back to no humming.
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I have everything plugged into 1 source power cord built into my players seat and the hum was not there. Thanks for all your help and replies. What a relief!
Jack Ritter
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Zum D10 8x5,rev pre-amp, TC M300, Split 12, n-112, IZZY, Hilton vp, Geo L, BJS Hughey, Live Steel |
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