Is it save to convert XLR to RCA?

The buzz was an issue in my amp which is balanced and my Dude preamp is single ended. I purchased a Jensen input transformer and placed it between my pre and amp. Dead quiet now.

Lissnr. Great!!! You will love the Dude. My Dude is just like yours.

I've had a few high end CD players where, when I used both the RCA and XLR outputs, there was a subtle (or bigger) degradation of the sound; don't know why. Anyone else experience this?

Hey there Grannyring.... sorry if I missed it in your previous posts but how did you end up eliminating the hum?

Excellent! How's that Jensen xformer working out for you? My Dude should be shipping to me soon...I've got butterflies...I actually built a larger, beefier stand to accommodate it too....(My Dude also has the 5 @ 6sn7's and the heavy duty transformer...). Stay in touch. Best

Yes, the buzz is gone and all is well!

Did you get your buzz solved?? Was hoping to talk about Dude some more too.

Could it be a speaker issue? I know it is passive, but.....

I can't envision a way in which a passive speaker could cause the symptoms you have described. But I guess it is conceivable that a problem involving the front end of the amp, or the interconnect cables to the preamp, could be AFFECTED differently depending on whether an electrostatic speaker or a passive dynamic speaker is being used.

Regards,
-- Al

It stays the same if all I do is turn off the amp and then turn back on. I may bring another speaker down to test as the problem only surfaced when a new speaker came into the system. Could it be a speaker issue? I know it is passive, but.....

All the ic's caused a buzz, but turning off the system and placing them in different positions changed the volume and channel of the buzz.

What happens if you don't change the cabling at all, but you turn the amp off, wait a few minutes, and then turn it on, and you repeat that whole cycle a few times. Does the volume of the buzz on each channel stay the same?

With the ic's connected to the direct inputs (RCA) on the amp no matter which input I chose on the selector the buzz was there. Did not matter as long as the ic's were connected.

When I connected the ic's into the crossover RCA inputs on the amp the noise was there wether I selected the RCA or XLR inputs on the crossover inputs. But with the ic's still connected to the crossover RCA inputs and selecting the direct RCA or xlr selection on the display the buzz went away.

This increases my suspicion that something is defective in the amp's input selection circuit. That's just a guess, though.

Regards,
-- Al

Ok , here is what I found. With the ic's connected to the direct inputs (RCA) on the amp no matter which input I chose on the selector the buzz was there. Did not matter as long as the ic's were connected.

When I connected the ic's into the crossover RCA inputs on the amp the noise was there wether I selected the RCA or XLR inputs on the crossover inputs. But with the ic's still connected to the crossover RCA inputs and selecting the direct RCA or xlr selection on the display the buzz went away.

Ok, I have no idea what that means. But this next thing is very strange. As I changed out IC's (I use the same brand -two sets of Fusion Audio Romance and even trying a set of Radio Shack ic's) as I change them in and out and back and forth from cd player back to amp etc the buzz would change from one speaker then to both etc.... All the ic's caused a buzz, but turning off the system and placing them in different positions changed the volume and channel of the buzz. Nothing consistent in terms of each ic, but always a change.

Now I have the same 2 sets of ic's back into the system and both channels now buzz at the same level. One channel is no longer louder then the other. That is most strange and I am ready to jump on my crazy system.....

My experience with hooking up ic's to an amp and leaving them open on the other end is a very loud and seemingly dangerous noise through the speakers.

Yes, if the RCA center pin comes in contact with, or perhaps even close to, a source of static electricity (such as your body), or anything that is at a different potential than the amp's ground. I should have thought of that when I posted.

In any event, you've established that the problem is not due to a ground loop, since it occurs when the amp is the only thing that is connected to AC power. So it would seem that the problem must be due either to EMI (electro-magnetic interference) pickup in the cabling and/or the preamp, from some nearby source of EMI, or to some defect in the input circuit of the amp. I found the Atlas manual online, and I see that it has a front panel switch to select among four possible inputs (balanced and unbalanced, direct and high-passed). I'm just speculating, but perhaps something is messed up in the switching circuit which causes the ground side of the RCA connectors to not be properly switched in.

If you haven't already, you might try switching among the various inputs, and/or unplugging the amp for a few minutes, to see if that clears out any improper states in the circuit that selects among the inputs. As the manual indicates, MAKE SURE THE AMP IS MUTED when the input selection is changed. Also, it might be worthwhile seeing if the same problem is present when you connect to the high-passed RCA input.

And if all of that leads nowhere, perhaps purchase an RCA-female to XLR-male adapter, that would allow you to try the XLR input on an experimental basis.

Beyond that, I'm pretty much out of ideas.

Best regards,
-- Al

My experience with hooking up ic's to an amp and leaving them open on the other end is a very loud and seemingly dangerous noise through the speakers. I don't think I will try that.... Right Al?

With the pre's ic's hooked up and the unit unplugged the buzz still lives.

The preamp need only be in the system and not turned on. Just the ic's hooked up to it.

What if the preamp is hooked up to the amp but not plugged into the AC outlet?

And what if the ic's are connected to the amp but left unconnected at the other end?

Sam -- good luck on your issue as well!

Best regards,
-- Al

Yes Sam. Chasing a buzz.

The preamp need only be in the system and not turned on. Just the ic's hooked up to it.

I ran a wire from the chassis of the pre to the chassis of the amp and still a buzz.

I'm empathetic, Grannyring...I'm chasing a buzz, the 60/120 Hz type, haha, as well. Elusive things, aren't they? ;-)

Regards,
Sam
p.s. Hi Al :-)

That all continues to be pretty baffling. Does the buzz still occur if the preamp is connected to the amp but the preamp is not turned on, or is not plugged into the AC outlet?

-- Al

Well I once again removed all from the amp except the speakers. Turned the amp on and no buzz. I do get some tube rush from the tweeter in one speaker, but that must be my input tube in that channel. Just a tube hiss, not a buzz through the highs and lows.

Step by step one thing remains the same.... As soon as I use any sort of preamp the buzz comes. I switched out my ic's and still the buzz. I used different power cords and still the buzz. I used cheaters on both, one and still the buzz.

I will check correct polarity from the outlet today.

I shorted pins 1 and 3 and still the same old buzz. I appreciate your help on this Al.

I see in John Atkinson's measurements that the Atlas has extremely high input impedance, which adds credibility to my theory that the problem may be due to hum pickup that occurs via the unused XLR inputs.

If you happen to have a multimeter, check for continuity between the center pin of an RCA input and pin 2 or pin 3 of the XLR connector for the same channel, and let us know.

If you don't have a multimeter, but you have a piece of wire of suitable gauge, try jumpering pin 3 to pin 1 on each XLR connector. Obviously, the jumper should only be inserted when the amp has been turned off for at least a minute or so, to assure that a transient won't be injected into the speakers. And the wire gauge should be such that its contact with the pins is secure, so that the connection won't be intermittent when the amp is turned on.

Alternatively, for experimental purposes you could order an RCA-female to XLR-male adapter, which would short XLR pin 3 to pin 1 (ground). Markertek, B&H Photo Video, and Musician's Friend are suppliers of that kind of thing, among many others. You could connect to the RCA input as usual, while having the adapter connected to the XLR input but in turn connected to nothing. Alternatively, for experimental purposes you could connect your RCA cable to the adapter, although depending on the design of the amp it's possible that could result in no signal going through one half of its balanced signal path, which would greatly reduce power capability and probably also have some adverse sonic effects.

If a jumper or adapter eliminates the hum, then yes, a Jensen transformer would be a good permanent solution, as it would provide a balanced signal pair to pins 2 and 3 of the XLR connectors.

Regards,
-- Al

I tried that and no help. I have sub on the second outputs of my preamp. When I remove the sub from the system, still the same buzz.

I wonder if that shorting jumper will work? Nothing in the manual. This Jensen transformer is said to help eliminate this sort of thing? My amp may also sound better thru the xlr input?

Granny, wow, that's mystifying. Sounds like you've tried pretty much all of the logical things.

Cheater plugs would have broken a ground loop, if that was the cause of the problem. And the Lightspeed wouldn't be susceptible to ground loop problems, because its power supply is optically isolated from the signal path, as I understand it. And also because it has a two-prong AC plug, with no safety ground connection.

You've probably already tried this, but if not try connecting the preamp and amp to the same dedicated line, and try doing that on each of the two dedicated lines.

I assume, btw, that nothing is connected to the outputs of the amplifier other than the passive speakers. I see that the Atlas is fully balanced, so if for instance a powered sub were connected to its outputs in the wrong manner, hum problems (or worse) could result.

The only other thing I can think of is that I see there is no switch on the back of the amp to select between the RCA and XLR inputs. Perhaps therefore the RCA input is wired directly to the same circuit point as pin 2 of the XLR connector (the non-inverting XLR input signal), in which case a jumper might be needed between pins 1 and 3 of the XLR connector when the RCA input is being used. Perhaps the manual addresses that. Perhaps the EMI environment is different now that the powered electrostatic speakers are no longer present, resulting in a difference in the amount of hum that is picked up by the floating input on pin 3.

Just some wild guesses, but I can't think of any other possibilities.

Regards,
-- Al

Al, I have a ground loop buzz I cannot get gid off and it is driving me out of my mind. I have tried everything. Cheaper plugs, changing IC's, isolating cables etc. My IC's are shielded .

I changed speakers and nothing else, but now a ground loop issue? Very strange. My old speakers were Soundlabs and they plugged into the wall. System was dead quiet through the speakers. My new speakers don't plug into the wall as they are not esl's. Nola Viper Reference.

With my amp only in the system and all other gear out, except speakers, the noise is gone. The cd plays no roll as I have removed it and still have the noise. When my pre is turned on - boom now the buzz. Problem is the same noise is their with my active pre or my passive pre. My passive does have an AC plug as it is the Lightspeed. My amp is the Aesthetix Atlas and my full time pre is the TRL Dude.

I don't know what to do and was thinking about trying xlr cables into the amp, thus my post above. Well it seems impossible to cure this issue. My home is new. I have 2 direct 20 amp lines for my stereo. All gear is plugged into the wall. No conditioners.

The noise is always a little louder out of one speaker. Volume plays no role.

Yikes!

Granny, as shown at the bottom of this page the "xx" in the part number gets replaced with letters specifying the type of input and output connectors. For RCA in and XLR out the model Bob mentioned would be DM2-2RX.

Before ordering, though, you should call Jensen and discuss your particular application with them, to be sure that is the most optimal model for your purposes.

Regards,
-- Al

Ok, I have a question. I want to use an xlr cable from my pre to amp. My pre is only RCA out. I want to purchase this Jensen transformer mentioned above and am not sure what to buy and if it will work? I assume they make one that accepts RCA from the pre and then use xlr from the Jensen out to my amp xlr? I did not see a pic of a Jensen unit so equipped?

Am I thinking right?

Yes, that looks like a good choice, Scott.

FYI, this Jensen paper may be of interest, with respect to long term applications as opposed to the temporary situation you are addressing.

Best regards,
-- Al

al, thanks so much. your willingness to share knowledge and your time is very appreciated. sounds like the correct way to convert an RCA preamp output to XLR such that an XLR IC can be used is to connect pins 1 and 3 to the ground such as is made possible via this adapter.

i really appreciate the guidance!

Hi Scott,

Is the solution different for converting RCA to XLR vs converting XLR to RCA?

Yes, absolutely. The two situations are very different.

It is highly preferable, and will be necessary in many cases, to ground pin 3 when adapting to an XLR input. Otherwise that input connection would be referenced to the component's circuit ground only through a high impedance (the input impedance of that input), which would create a susceptibility to hum and noise.

On the other hand, grounding pin 3 of an XLR output accomplishes nothing constructive, and creates the risk that the circuit or device providing that output signal will misbehave (or even be damaged if it is not well designed) as a result of the excessive amount of current that will be drawn by the short circuit. See this thread for an example.

Best regards,
-- Al

Al, i am considering using an RCA-XLR adapter to convert the RCA output on a preamp to XLR such that i can use am XLR-XLR IC to an XLR input on my power amp (power amp can take either, but i only have XLR IC's presently). this is temporary until i purchase a pair of RCA IC's.

regarding connecting pins - the advice in this thread is to leave the pins open. there was an interesting conversation between you and Ralph (atma-sphere) where i thought the recommendation was to connect the pins here:

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1280795210&openfrom&1&4#1

"...To correct this, open up the XLR side of the adapter and have someone (if you can't solder) connect pin 1 of the XLR (ground) to the unused connection (often pin 3, which is the inverted input).

This will get rid of the hum and the amp will have normal gain..."

is the solution different for converting RCA to XLR vs converting XLR to RCA? just trying to figure out the best way to use an XLR IC with an RCA preamp output.

Assuming you get the correct adaptor, while you will have no benefit going from balanced to RCA, it shouldn't be worse than RCA-RCA.

Also, if you go with an RCA splitter, I would go with a one-piece metal splitter, rather than a Y-cable.

+1 to all the above. I use Cardas XLR > RCA adapters to connect preamp to subwoofers. Cardas disconnected pin 3 for me at no extra charge.

The 4V refers to the DIFFERENCE between the non-inverted and inverted signals that are provided to pins 2 and 3, respectively, of the XLR connector. Each of those signals individually has a maximum amplitude of 2V. By adapting the XLR output to an RCA input, you would only be using one of those signals (the non-inverted one), so the RCA input would see a maximum amplitude of 2V.

Something to keep in mind, however: Most XLR-to-RCA adapters, and perhaps some adapter cables, short the inverted signal on XLR pin 3 to ground (XLR pin 1). Many components won't have a problem with that, but some will (if it is done on an XLR output; it is no problem on an XLR input). Use an adapter or adapter cable that leaves pin 3 unconnected. Talk to the supplier to be sure that is what they will provide.

Another approach to consider would be to just use the RCA output, via a y-adapter that would allow you to connect it to two destinations. That should work fine as long as the total of the two cable lengths is not extremely long.

Regards,
-- Al

The above answers are correct, I've done it without issue to drive a subwoofer when I didn't have an extra pair of rca out. Worked well.

There is no benefit going XLR to RCA. The 4V you get from balanced XLR is voided when going to RCA.
You wont damage any equip., but you wont get the benefit of balanced XLR. In your case, RCA to RCA is the right way to go.

John
JW Audio

Thanks so much for the response, folks!!

I am fully aware I'm losing the XLR benefits by using a convertor. I just want a second output.