Unwanted Hum IN effects loop!

  • Thread starter Thread starter DogRox
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DogRox

DogRox

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OK... i have this problem that seems to be just annoying lately

I have a 488 MKII with the Effect send 1 going in to a rackmounted Yamaha SPX-90.... and the two (left and right) returns coming back in to the 488 using the 9/10 Stereo inputs!

Everything seems to be working but i get this bad HUM! and cant seem to get rid of it no matter what i do!..tried new cords.
Nothing worked. I know the HUM is in the effects loop cause when i unplug the effects from the 488 the hum goes away!

I changed the input signal level switch on the back of the YAMAHA SPX-90.. but going to -20db seems to cut the effects compleletly out.... and the +4db seems to bring the hum in! There is also a level switch for the output too! which has the same levels but does the same thing.

ANY Ideas what i can do to clean this system up would greatly be appreciated! What should the level switches be set to?

I also have a rack mounted ROLAND M160 line mixer which has a PEAVEY ULTRAVERB in its effect loop.. and i also get hum from that!... but the Peavey has no level switches in the back.. but the M-160 does.. and when i also switch that i lose effect or gain the hum!


any help would definately be appreciated!

thanx!

dog
 
Hey Blue Bear

thanx for the input.. i already ran across that second link before i posted here... and that doesnt really seem to tell me anything except between balanced and unbalanced... and wiring diagrams for each...

tho the simple connection between the tascam effect send and stereo inputs are just standard 1/4 inch connections.. which is what i am using!

and as far as the other site they are just telling me basically NOT TO REMOVE GROUND PLUG.. which hasnt been removed.

I am wonderign if the problem is in the rack? itself? , anbd the ground loop coming from that?? i.. i wonder if there is anything i can do wiht that to help remove the hum? like i say i get the hum in both the line mixer effects loop and also he tascam effects loop.. but they both have a different effects processor!

this is like a headache.. and it really gives you headaches too when trying to monitor the signal.... and the other thing that buggs me is .. that i cant get the effect signal strong enough in the tascam ... just seems to be weak in comparsion the to the dry signal! and all settings are set to the 488 's manual!

thanx again!
 
DogRox said:

and as far as the other site they are just telling me basically NOT TO REMOVE GROUND PLUG.. which hasnt been removed.
Click to expand...

No, I don't think that is what the Bear was saying. Absolutely, the ground prong should be left intact. But where you plug it in is the issue here.

Before the hum started, did you change the way you had your gear plugged in? Or has the hum been there from the beginning? Have you just recently set up or relocated the studio?
 
Then you didn't read the first article very carefully -- there are 2 links in the "Transformer isolation of whole studio system" section that are relevant and practical to your situation..........
 
yo,.... ok i went back to the first site again.. and read those links.. i printed them out..

i also found a nother site last night.. that showed how the ground loops can happen in a RACK system.. and i think thats where my problems are like in what digitalsmigital (kewl nick name hehe) was talking about

I have alwasy had a small deal of hum before.. but i think thats cause of the rack mounted tascam patchbay i have on the bottom of the rack to patch my effects to to my 488.


but since i changed the power strip a few months ago.. i think thats when my the hum started to increase.. so reading that other site.. they basically say to start unpluggin everything till you have basically the mixer and plug one item in one at a time.. and see what one is acting the problem... just cause the SPX-90 effects processer SEEM like it is giving the hum in to the 488 doesnt mean that is basically the culprit and could be getting hum from another device.. that is why i also got hum in to the line mixer with the peavey effects!

I will have my buddy come over sometime to help me wiht this rack cause it is to heavy for me to move.. but then i will go through and check ...

i think i am on the right track!..

but now the only problem i will have is ther low effects sounds.. maybe once i get the hum out i can get back my effects gain!

thanx for the help.. cheerz

dog
 
Hello... sorry i havent been back on here with my results of my humm problem.. but anyways.. here is what happened.... there was a major ground hum.. i couldnt figure out where it was coming from.

After narrowing it down to my PC computer, i found that it was my PC midi cable. It was that cable that hooks to the sound card. After research i found that it wasnt broken or anything.. but the PIN #2 on MIDI IN (to computer) connector.. was Grounded.. that was how it was made from the factory... Granted it is fine for hooking up one midi keyboard to the computer.. thats great.. but with the extensive midi setup i have it was leaking through my midi router.

Remedy: i have a couple FEMALE midi couplers that i bought for like 3$ each... i took one of them apart.. removed all the plastic surrounding the wirses.. which left me with just two seperate female midi connectors.

I cleaned off the pins... on both connectors. I litterally pulled the metal contacts out of both connectors.. that were NOT needed.. one BEING pin #2. .. anmd i think the others were 4 and 5... which left me with ONLY pins 1 and 3.

which i soldered wires to the m both to the other connector.. keeping in mind what pin was what so it didnt mix them up.

I i put a spacer in between the two female ends.. so that they wouldnt touch each other and short the pins.. and thentaped it all back up.

I hooked it to my MIDI IN to my computer and shure NUFF the HUM was GONE!... and my midi worked fine!

That saved me form hacking to the main PC/midi cable.. as thay are NOT cheap!... so i modified the midi coupler instead...

NO HUMM!! :o) just letting you know what was going on .. thanx for all the tips tho!

Cheerz
 
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