Ok so I'm about ready to give up.
I just purchased 3 of the RCA to 1/4 inch cables becasue i heard they would solve my problems. Not only is the audio quality much lower, but the humming is even worse. So theres another 50 bucks wasted. If this is the case, how does anybody use pro audion stuff in the home? I've tried both xlr to rca and 1/4 inch to rca and nothing has worked.
Somebody help me please!
I just purchased 3 of the RCA to 1/4 inch cables becasue i heard they would solve my problems. Not only is the audio quality much lower, but the humming is even worse. So theres another 50 bucks wasted. If this is the case, how does anybody use pro audion stuff in the home? I've tried both xlr to rca and 1/4 inch to rca and nothing has worked.
Somebody help me please!
paulspencer said:
The signal passes through the same electronics no matter if its ballanced or not. You don't bypass anything by feeding an unballanced signal into a ballanced input.
Running ballanced DOES help with ground loop induced noise as you can earth lift one of the ends. Its why pro audio is all ballanced as you can never rely on the earth in a venue being any good.
Well its definetly coming from the cables as the noise changes when i slide the 1/4 inch jacks in and out of their outlets. I cant imagine how its a grounding issue because before I introduced the pro audio components i had just standars RCA's everywhere and I never had a problem. Then i added the ep2500 and the ultragraph pro and everything went to hell.
Ok let me explain the setup. Ive got 2 technics amps that are pushing 4 floor standing technics speakers (one pair per amp), and i then have the signal split to a paradigm crossover to the ep2500 to power the subs. So basically, I have 6 connection points (equalizer ins and outs, and the 2 ins for the ep2500) that need to be adapted from either rca to xlr, or rca to 1/4 inch. Also, the ultragraph equalizer is the main eq for the 2 technics amps. So basically, the humming is not only for the 2 subs, but its for the entire system through all floorstanding speakers as well. So there isnt a chance to run balanced between eq and sub because there isnt a connection. ALSO, i just checked the amp and there isnt an earth lift switch, and even so then im still stuck with the problem of the EQ humming.
Thanks so much guys!
Thanks so much guys!
It's ESSENTIAL! to only have ONE earth connection for the entire system, this isn't just for pro gear, it's for domestic gear as well. If you have more than one earth, then current passing through the ground connections induces hum into the audio - it's a well known effect.
Pro-gear often overcomes it by using 'ground lift' switches, which disconnect the ground on the input socket, effectively disconnecting the screen at one end. Domestic gear is often made as 'class II' with no earth connection at all.
Pro-gear often overcomes it by using 'ground lift' switches, which disconnect the ground on the input socket, effectively disconnecting the screen at one end. Domestic gear is often made as 'class II' with no earth connection at all.
BlackCatSound said:
As I understand, balanced outputs mean that additional circuits are added in the signal path to the balanced output jacks. If the unbalanced outputs are used from a unit, then surely these circuits would be bypassed and not in the signal path.
I don't have any special knowledge on this, however, it seems logical that it would be done this way. If you can back up that statement, then please do fill me in.
paulspencer said:
Its the same circuit that feeds both. Its just the ballanced connector has the normal signal plus an inverted version of it.
A DI box is used to feed a line level signal into a microphone input on a mixing desk, not what you need.
You need a ballanced cable between the ultragraph and the amp but do not connect the earth, just connect hot and cold.
Also on the feed to the ultragraph wire the centre pin of the RCA to hot on the ballanced jack/XLR and the shield of the RCA to cold on the jack/XLR.
If you're using XLR leads, then there will be three wires inside the plugs, two are normal insulated wires, the third is the screen (or shield) and has no insulation on it. It's this uninsulated wire which should be disconnected.
If you're using 1/4 inch mono jack plugs (there's no reason for you to be using XLR's), there's only two wires, an insulated one to the tip, and the screen to the sleeve - again, disconnect the screen.
If you're using 1/4 inch mono jack plugs (there's no reason for you to be using XLR's), there's only two wires, an insulated one to the tip, and the screen to the sleeve - again, disconnect the screen.
Hi CARTRulz, these days most everyone in the West wires balanced XLR connectors:
Pin 1 - ground, either circuit, chassis or switchable
Pin 2 - signal positive
Pin 3 - signal negative (not ground!, signal negative has audio on it out-of-phase with Pin 2)
Interfacing from balanced to unbalanced gets complicated because there are so many variables on the balanced side. Unbalanced is easy, centre pin carries the signal, outer 'pin' is system reference or ground. The balanced side has three common types - transformer-coupled passive balancing, instrumentation-type active balancing, and 'generic' active balancing. The first two are true isolated balancing in that impedance between either balanced leg and circuit ground is extremely high, on the order of mega ohms. An instrumentation amp is an active circuit designed to emulate a transformer. For both these types using only Pin 1 (ground) and one of either signal pins won't work. To visualize why, consider connecting an unbalanced source to a transformer input using only pins 1 and 2. Pin 3, the other end of the transformer primary, isn't connected to anything so no current flows (in reality almost no current, physical imperfections like winding capacitance allows a little signal through.) Generic active is sometimes called 'pseudo balancing', both inputs are referenced to ground. It's the equivalent of two unbalanced inputs/outputs, each independent of the other handling a different phase. These factors limit how ground is handled.
Examining unbalanced output to balanced input connections first:
Transformer coupled in - RCA centre pin to XLR pin 2, RCA ground to XLR pin 3, optionally (and likely) connect XLR pin 3 to XLR pin 1 to reduce hum
Instrumentation amp in - Generally same as above
Generic Active in - RCA centre pin to XLR pin 2, RCA ground to XLR pin 1, optionally tie XLR pin 1 to XLR pin 3 to reduce noise
Now the output side, balanced to RCA unbalanced:
Transformer coupled output - XLR pin 2 to RCA centre pin, XLR pin 3 to RCA ground, optionally connect XLR pin 3 to XLR pin 1 to reduce hum, often not required
Instrumentation amp output - Generally same as above
Generic Active output - XLR pin 2 to RCA centre pin, RCA ground to XLR pin 1, do not tie XLR pin 1 to XLR pin 3. Doing so shorts one leg of the output to ground.
The first two output connections preserve the full output voltage swing, the latter loses 6 dB since only one leg is available for use. In reality there is no true 'balanced' connection to unbalanced equipment, you're really just messing around with grounds. My suggestion for unbalanced out to balanced in is: RCA centre pin to XLR pin 2, RCA ground to XLR Pin 1, tie XLR Pin 1 to XLR Pin 3. For balanced output to unbalanced input: XLR Pin 2 to RCA centre pin, XLR pin 1 to RCA ground. Only tie XLR pin 3 to XLR pin 1 only if the output completely lacks bass if left unconnected. And by that I really mean sounds like a telephone, or is very low in level.
Pin 1 - ground, either circuit, chassis or switchable
Pin 2 - signal positive
Pin 3 - signal negative (not ground!, signal negative has audio on it out-of-phase with Pin 2)
Interfacing from balanced to unbalanced gets complicated because there are so many variables on the balanced side. Unbalanced is easy, centre pin carries the signal, outer 'pin' is system reference or ground. The balanced side has three common types - transformer-coupled passive balancing, instrumentation-type active balancing, and 'generic' active balancing. The first two are true isolated balancing in that impedance between either balanced leg and circuit ground is extremely high, on the order of mega ohms. An instrumentation amp is an active circuit designed to emulate a transformer. For both these types using only Pin 1 (ground) and one of either signal pins won't work. To visualize why, consider connecting an unbalanced source to a transformer input using only pins 1 and 2. Pin 3, the other end of the transformer primary, isn't connected to anything so no current flows (in reality almost no current, physical imperfections like winding capacitance allows a little signal through.) Generic active is sometimes called 'pseudo balancing', both inputs are referenced to ground. It's the equivalent of two unbalanced inputs/outputs, each independent of the other handling a different phase. These factors limit how ground is handled.
Examining unbalanced output to balanced input connections first:
Transformer coupled in - RCA centre pin to XLR pin 2, RCA ground to XLR pin 3, optionally (and likely) connect XLR pin 3 to XLR pin 1 to reduce hum
Instrumentation amp in - Generally same as above
Generic Active in - RCA centre pin to XLR pin 2, RCA ground to XLR pin 1, optionally tie XLR pin 1 to XLR pin 3 to reduce noise
Now the output side, balanced to RCA unbalanced:
Transformer coupled output - XLR pin 2 to RCA centre pin, XLR pin 3 to RCA ground, optionally connect XLR pin 3 to XLR pin 1 to reduce hum, often not required
Instrumentation amp output - Generally same as above
Generic Active output - XLR pin 2 to RCA centre pin, RCA ground to XLR pin 1, do not tie XLR pin 1 to XLR pin 3. Doing so shorts one leg of the output to ground.
The first two output connections preserve the full output voltage swing, the latter loses 6 dB since only one leg is available for use. In reality there is no true 'balanced' connection to unbalanced equipment, you're really just messing around with grounds. My suggestion for unbalanced out to balanced in is: RCA centre pin to XLR pin 2, RCA ground to XLR Pin 1, tie XLR Pin 1 to XLR Pin 3. For balanced output to unbalanced input: XLR Pin 2 to RCA centre pin, XLR pin 1 to RCA ground. Only tie XLR pin 3 to XLR pin 1 only if the output completely lacks bass if left unconnected. And by that I really mean sounds like a telephone, or is very low in level.
Ok now heres where I'm very confused. I purchased these the other day"
http://www.amazon.com/gp/product/B0...ref=sr_1_2/002-5117543-7840864?_encoding=UTF8
However, I'm still getting hum. Is that becasue its going from ballanced to unballanced? So basically when I follow those directions I'll be making a cable thats staying unballanced to unballanced, which will eliminate humming, correct?
http://www.amazon.com/gp/product/B0...ref=sr_1_2/002-5117543-7840864?_encoding=UTF8
However, I'm still getting hum. Is that becasue its going from ballanced to unballanced? So basically when I follow those directions I'll be making a cable thats staying unballanced to unballanced, which will eliminate humming, correct?
Ok so heres what I got now. I bought 6 RCA to XLR cables. On the RCA side there is one insulated wire from the pin and one straight piece of metal that goes from the ring and has a wire soldered to that, which then comes in contact with the metal sleve that screws into the head. On the XLR side there are 3 wires. One insulated thats in pin 3, and 2 uninsulated that go to pins 1 and 2. However, this seems to go against what Nigel said, as the insulated wire on the XLR side goes to the pin on the RCA side, which carries the signal, correct? Im so lost, someone please send help!
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