stargate69

stargate69

Audiophyte
I think I've tried everything to remove hum from my Proaudio powered subs, to no avail. Used a DI box, but WASN'T happy with the 'trade offs'. Someone told me my RCA to XLR cable needed to be 'rewired'...Is this possible/true?? How does anyone else out there go from HT set-up to Proaudio POWER for their subs, w/o going thru another 'box' ??? Would appreciate ANY thoughts/advice.... I'm no electrician, but think I know enough ( ground loops? what are THEY??? ) Thanx, B C
 
lovinthehd

lovinthehd

Audioholic Jedi
What cable do you have? Try this article. Have you tried a rca to TS connector instead?

What amp? My pro amps have rca ins so no big deal for me :).

Have you tried a cheater plug to see if the hum goes away if it is ground loop related?
 
highfigh

highfigh

Seriously, I have no life.
I think I've tried everything to remove hum from my Proaudio powered subs, to no avail. Used a DI box, but WASN'T happy with the 'trade offs'. Someone told me my RCA to XLR cable needed to be 'rewired'...Is this possible/true?? How does anyone else out there go from HT set-up to Proaudio POWER for their subs, w/o going thru another 'box' ??? Would appreciate ANY thoughts/advice.... I'm no electrician, but think I know enough ( ground loops? what are THEY??? ) Thanx, B C
List the equipment in your system and look at how it's powered- is it all on one circuit, is it on two or more (likely, if the sub is in another part of the room)?

If the amplifier(s) use RCA a well as XLR inputs, try the RCA without adapters. I found that a Krell preamp and power amp had a ground loop with XLR, but not with RCA- if it works, leave it.

The difference in the sound won't be enough to make using one or the other an issue that's important. The sound is the same, the input signal may not be as high and the theoretical noise level will be higher (maybe) but it shouldn't be noticeable if any audible signal is present.

On of the first threads at the top of the forum explains ground loops- read it and do what it says.

Did you buy the XLR-RCA adapters, or make them? Are they a simple XLR plug on one end and an RCA on the other, or does it have a transformer inside, to provide the proper impedance?
 
TLS Guy

TLS Guy

Seriously, I have no life.
What you are doing is called floating a line. There is a lot of misunderstanding about this. It is very easy to create a ground loop.

If you bought your adapters I suspect they are wired like this.


But since the RCA end is the source they need to be wired like this.



Now you might think that this would make no difference.

However only pin one is a ground. Pin 3 is not really a ground and not connected to ground in your amp. Both pins one an two are actually isolated from ground, the pin two carrying the positive side of the wave form, and pin 3 the negative half of the wave form.

So in order to make it work you have to make pin 3 a ground also. Where you do this matters.

This connection needs to have minimal resistance between pin 1 and two at the input to the amp.

If you wire it like the top diagram, then you will very likely create a ground loop because the screen (black) and the blue cable are different and will have small but differing resistances. This is the essence of a ground loop.

The first job is to connect the proamp correctly.

This may not solve it as many pro amps are notorious for internal ground loops when connected unbalanced. Then you will have to use a cheater plug to lift the ground. If you are worried about electric shock then you need to bond all your grounded units to ONE ground with 5 gauge copper wire.
 
Verdinut

Verdinut

Audioholic Spartan
If you use the proper RCA Male to XLR Male cable, you shouldn't have a problem.

Have a look at this link which explains in detail the recommended connections. (See #17):

http://www.rane.com/note110.html

I know that Monoprice have some of those properly wired cables which you can get at a very reasonable price.
 
TLS Guy

TLS Guy

Seriously, I have no life.
If you use the proper RCA Male to XLR Male cable, you shouldn't have a problem.

Have a look at this link which explains in detail the recommended connections. (See #17):

http://www.rane.com/note110.html

I know that Monoprice have some of those properly wired cables which you can get at a very reasonable price.
Monoprice say they have them but they don't.

He needs RCA to XLR and not XLR to RCA. As I outlined above the wiring is different which way you go.

Most of these cables are XLR to RCA. RCA to XLR are hard to find.

B & H have this 2' cable which will do the trick as he can extend it with an RCA to RCA cable.

The problem is that with pre made cables you can never be sure they are described correctly.

Honestly this is so important you should always make these cables yourself so you know it is correct.
 
stargate69

stargate69

Audiophyte
Two QSC RMX 2450s Feeding 4 15in Titanics from PartsExp ( Did I JUST discover they're Class H amps ??! )
 
stargate69

stargate69

Audiophyte
Nice setup! Hope you lick the hum issue!
I THINK I have...there IS another way to wire that cable! AND I've made other doehead discoveries that mite solve the issue! It really HELPS when you THOROUGLY read and understand your OWNER'S MANUALS!! LOL
 
TLS Guy

TLS Guy

Seriously, I have no life.
His amps have TRS connectors. If he goes RCA to mono 1/4" it will make the correct connection!
 
Pogre

Pogre

Audioholic Slumlord
I THINK I have...there IS another way to wire that cable! AND I've made other doehead discoveries that mite solve the issue! It really HELPS when you THOROUGLY read and understand your OWNER'S MANUALS!! LOL
RTFM is a piece of advice that's given here quite often. :p
 
jinjuku

jinjuku

Moderator
I THINK I have...there IS another way to wire that cable! AND I've made other doehead discoveries that mite solve the issue! It really HELPS when you THOROUGLY read and understand your OWNER'S MANUALS!! LOL
Any updates? Nice multi-sub setup you have.
 
stargate69

stargate69

Audiophyte
Any updates? Nice multi-sub setup you have.
Too many other things goin on, frustrated with 'electronics' in general, have an OLD Kenwood integrated amp that's feeding for the time being. Am impressed at what 100 watts will do in my smallish room thru the subs! Now that I'm 'smarter', I have a few things to try, along with getting THAT cable rewired .....Nice system(s) you have!
 
TLS Guy

TLS Guy

Seriously, I have no life.
Too many other things goin on, frustrated with 'electronics' in general, have an OLD Kenwood integrated amp that's feeding for the time being. Am impressed at what 100 watts will do in my smallish room thru the subs! Now that I'm 'smarter', I have a few things to try, along with getting THAT cable rewired .....Nice system(s) you have!
For the last time you do not need that cable rewired. You have TRS connectors. You just need RCA cables and these adapters plugged into the TRS connectors.


I have already explained this to you twice in PMs. Now this is the third time.

This will do exactly the same as rewiring your cables, in fact a better job.

Quire honestly you are working hard to get the alcoholics TSTOE award
 
Last edited:
stargate69

stargate69

Audiophyte
For the last time you do not need that cable rewired. You have TRS connectors. You just need RCA cables and these adapters plugged into the TRS connectors.


I have already explained this to you twice in PMs. Now this is the third time.

This will do exactly the same as rewiring your cables, in fact a better job.

Quire honestly you are working hard to get the alcoholics TSTOE award
OK,OK, I get it....NO rewiring plans....I'm a procrastinater....I've bought every commercially available adapter, etc. I need to plan a day and go thru my system and rid me any/all inline gremlins now that I have 'more knowledge'....THANK YOU ONE AN ALL for your help and advice....Will update this thread and let you know when my 'problem' is solved....When I find that 'rountoit'o_O
 
TLS Guy

TLS Guy

Seriously, I have no life.
OK,OK, I get it....NO rewiring plans....I'm a procrastinater....I've bought every commercially available adapter, etc. I need to plan a day and go thru my system and rid me any/all inline gremlins now that I have 'more knowledge'....THANK YOU ONE AN ALL for your help and advice....Will update this thread and let you know when my 'problem' is solved....When I find that 'rountoit'o_O
I hope three times is a charm!
 

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