Help required with Studio Monitors, PC and Mixer SetUp

[bobinz]

Hi Audioholics,

I've recently embarked on improving my set-up with my current equipment. At the moment, the system works - but with a few problems, I have troubleshooted as much as I can so I'm really hoping you guys can assist me!

The equipment:
Behringer B2031As Self-powered studio monitors (XLR to RCA connection)
Behringer DJX750 4-channel mixer
PC with standard onboard 6 x 3.5mm jack connections
Logitech 5.1 Desktop Speakers (These are not so important, just another source of output as the mixer has Master and Booth outputs.)

Intended operation:
Currently, I have my room set up so that the computer desk faces one wall with my Behringer monitors positioned either side of it. Directly behind this is another desk where I do all of my mixing, so here resides my turntables, mixer and other synth gear.

The aim for this set up is to be able to use my studio monitors for both mixing and computer use.

Connections:
Behringer B2031As are connected to the mixers master output channel using L/R XLR jacks to L/R RCAs.
Logitech speakers are connected to the mixers booth output channel using a 3 x 3.5mm to L/R RCA converter (this comes standard with most Logitech speaker products).
Computer is connected to a Line-In channel on the mixer. This is achieved by (from the PC) a 3.5mm to L/R RCA converter plugged into the Green TRS 3.5mm on the board. Then the L/R RCAs travel to one of the mixers Line-In channels.

Current problems:
So with this current set-up everything does indeed work, but with a couple of problems I just cannot get around. I will describe them here:

*My right monitor is definitely not playing as loud as the left, and it does not play any low frequencies (Does not happen when computer is disconnected from mixer). With the research I have done I am lead to believe this is an unbalanced issue(?). This is beyond my current understanding, I hope the volumes and frequencies they omit can be equalized.

*All speakers are omitting very obvious noise. Hard to describe, but it is almost like a random digital interference, doing something like moving the mouse seems to effect it, but it is very hard to tell. Again, the speakers are not effected by this when the PC is disconnected from the mixer and used for mixing on their own.


I have a variety of cables, converters and connectors available to use. For example, I have tried taking the 3.5mm to L/R RCA converter (at my PC) out of the equation and replacing each RCA with its own 3.5mm jack and plugging them into Green/Black connections on the PC. I have also tried a variety of other combinations in attempt to rectify my problems but to no avail.

Very much hoping you guys will be able to help me out here, please advise if any further information is needed and I will promptly reply.

Thanks in advance,

Bobinz.

 

[BoredSysAdmin]

Your monitors have Unballanced connector - I'd start by taking xlr->rca adapter out of equation.
It sounds like in your situation you don't need to use xlr connector anyway - it does not bring any benefit for short runs

 

[jinjuku]

1. Have you swapped speakers to see if the problem stays or follows? **Edit sorry it seems it is fine when the PC isn't connected. You have 2 potential, cumulative, issues: Cabling and mainboard integrated audio. Tackle the Cabling first and see if it fixes the second. How long are your RCA runs from the Mixer to the Speaker?

2. You are using the motherboard audio

You need to try a sound card either external or internal that will have proper shielding.

I can replicate HD and Mouse movement noise with an unbalanced (RCA) connection on my EMU 1212M. If I incorrectly design the TRS to RCA and leave the shield connected at the TRS end (computer side). This will pickup all the noise with a Switch Mode Power Supply that is typical in computers. I switched up to a DC<>DC ATX converter and external Linear Regulated DC 10 AMP 12V Tripplite (see my sig) and I can't get noise out of the system in any way shape or form.

The 1212M is fine with a SW PSU and correctly designed cables however.

The RCA to XLR cables, can you remove the XLR boot and snap a pic of the wiring? This may help.

You could also look at a balanced mixing console. It stand a good chance at rejecting the noise you are hearing induced.

What area do you live in? A Craigslist search for a Pro-Audio sound card would be worth it. If you picked up something like the EMU 1616M you could dump your mixer BTW and just use the software mixer (PatchMix in the case of the EMU)

 

[BoredSysAdmin]

If you're not fully committed to do the drastic step as converting to external psu, adding a filtering ac surge protector helps a bit as well as changing to sound card as jin mentioned.

 

[jinjuku]

If you're not fully committed to do the drastic step as converting to external psu, adding a filtering ac surge protector helps a bit as well as changing to sound card as jin mentioned.

He should be ok with a standard PSU. I did what I did just because the cost was negligible vs a SM PSU w/o Fan.

 

[bobinz]

Thanks for the prompt replies guys!

I will start by taking the XLR jack connections out of the equation and replace them with XLR3 connections (the other input option on my monitors), however my mixer only allows for RCA connections on the Master/Booth, will converting back to RCA from XLR3 nullify the process?

I do have a Creative Sound Blaster external sound card which I have tried, but no success there. However I can understand how using onboard sound would definitely incur noise without proper shielding so I will test this external card again with the new monitor connections.

I do have 2 sets of RCA joiners in my setup, these are for the RCA leads running from the PC to mixer and the leads running from monitor to mixer. In total they are not much longer than 5m each - is this a problem?

I will look into a balanced mixing console and other equipment you have listed, jinjuku - thanks!

I am in Perth, Western Australia so unfortunately craiglist is almost non-existent out here haha..

The only other thing is AC filtering surge protector, is this the actual power board? Because I do already have a quite good one from Belkin.

Would it be a fair statement to say that the noise is probably occurring due to the connection from onboard audio jacks?

 

[BoredSysAdmin]

This "XLR3" port is capable to be unbalanced so for you is nothing but a female 1/4" TSR connector. all you need a simple adapter to rca like this one:
American Recorder Technologies 1/4" Male Mono to RCA Female Adapter and more Cable Adapters and Connectors at GuitarCenter.com.
or a cable like this one:
Hosa CPR110 (10') | Sweetwater.com

and yes - this should take (possibly bad) xlr adapter unbalanced to balanced out of equation.

and then I meant filtering probably a UPS would you best call, but I used this product: ISOTEL6ULTRA - 6 outlets, 6-ft cord, 3330 joule, 2 line modem/fax protection, All metal housing Isobar Surge Suppressor - Premium surge, spike and line noise protection

btw: I suspect what you have a ground loop issue

 

[bobinz]

This is currently the cable I am using. The 1/4" TRS runs from the monitor and is a RCA at the other end. These run into the mixer. On the monitor this is labeled as the unbalanced option for input. If I take an XLR3 cable (the balanced option) that becomes an RCA for the mixer will my monitors volumes and frequencies balance out?

 

[bobinz]

Ahh ok. Just to clarify guys, I've just figured out the difference between 1/4" TRS and xlr. I stated in my original post that I'm using xlr to RCA cables for my monitors. In actual fact I am using 1/4" TRS to RCA, the TRS is labeled as the unbalanced input option on my monitors.

So if I switch to xlr to RCA will this be balanced? (The xlr input is labled as balanced on the monitors) Or does having an xlr that becomes RCA defeat the purpose of this in the first place. I.e will the signal become unbalanced by converting to RCA?

 

[jinjuku]

Ahh ok. Just to clarify guys, I've just figured out the difference between 1/4" TRS and xlr. I stated in my original post that I'm using xlr to RCA cables for my monitors. In actual fact I am using 1/4" TRS to RCA, the TRS is labeled as the unbalanced input option on my monitors.

So if I switch to xlr to RCA will this be balanced? (The xlr input is labled as balanced on the monitors) Or does having an xlr that becomes RCA defeat the purpose of this in the first place. I.e will the signal become unbalanced by converting to RCA?

You can NEVER have a balanced connection with RCA. RCA by definition is an unbalanced connection.

Since it is TRS go to Radio Shack and get a pair of TS to RCA and let us know.

It is imperative that you under stand there is a world of difference from TS and TRS. Check out the Rane Application Note for wiring interconnects. It stays in the toolbox I keep all my termination gear in.

My best advice to you is dump that unbalanced mixer and go with a computer based mastering product.
Trust me go fully balanced if you can. It will save you some heart ache.

 

[jinjuku]

Thanks for the prompt replies guys!

I will look into a balanced mixing console and other equipment you have listed, jinjuku - thanks!

I am in Perth, Western Australia so unfortunately craiglist is almost non-existent out here haha..

If I can find you something in the States I will. I'll do it at whatever the cost is + customs+3% credit card (this is what I pay Visa/MC for card not present transactions).

We can do this over PM.

There is a Delta 1010 Rack Mount for $140 near me.

Here is the page at M-Audio.

Research and Due Diligence is up to you however. I can verify that it works. It requires a PCI slot. Not PCIe, but PCI.
Looks like there is driver support for XP/Vista/Win7 (64bit is in Beta release I believe).

 

[BoredSysAdmin]

Y
Trust me go fully balanced if you can. It will save you some heart ache.

So, you are saying that for me (simple pc audio setup: pc to monitors) I would benefit going to balanced interface ?

for example like this card:
M-Audio Delta 44 PCI Sound Card 9900-50757-00 B&H Photo Video

Rack product is way to big to fit on my desk, except as a stand for monitor

Thou I for the most part have no more ground loop issues, sometime I can hear them but really really barely noticeable

 

[jinjuku]

So, you are saying that for me (simple pc audio setup: pc to monitors) I would benefit going to balanced interface ?

for example like this card:
M-Audio Delta 44 PCI Sound Card 9900-50757-00 B&H Photo Video

Rack product is way to big to fit on my desk, except as a stand for monitor

Thou I for the most part have no more ground loop issues, sometime I can hear them but really really barely noticeable

In his situation he has the ability to go balanced from soup to nuts if he uses the computer as the main source. So for him it will solve some problems.

I don't know what your setup is.

 

[BoredSysAdmin]

I don't know what your setup is.

it's in my sig, see PC part - the cable used is 3.5mm mini-jack stereo to two rca male from monoprice (premium version) of course unbalanced

 

[jinjuku]

it's in my sig, see PC part - the cable used is 3.5mm mini-jack stereo to two rca male from monoprice (premium version) of course unbalanced

If your setup works, it works.

But let me give you an example from my setup. With the 1212M I can add the external break out box for a total of 6 Analog I/O either balanced or single ended. I can then route the mix to additional channels (amp) then then to sub(s) and the 1212M also can do a PEQ on them from PatchMix DSP.

 

[bobinz]

Thanks for the help all, have solved my equalization issues.

jinjuku, I will keep in contact via PM if I need to arrange a purchase from the U.S.

Still having issues with the interference, but I'm sure it won't take much to fix. Cheers guys!