Is it SAFE to run a balanced +20 dbu signal to an RCA unbalanced headphone amp?

[jonwb]

Hi... Thought I'd ask first. My Lynx PCIe card outputs a stereo balanced signal of +20 dbu (pretty hot). I want to run this to a Topping headphone amp with RCA inputs. I bought these adapter cables from Amazon and I included its wiring diagram (see pics)

Is it safe to connect this or do I risk damaging something?

Thanks

 

[DonH56]

From an XLR output, I normally leave pin 3 (signal negative) floating to avoid shorting the driver's output. Pin 1 to RCA ground (shield), and pin 2 to RCA center pin. Whether grounding pin 1 is a problem depends upon the driving component's output stage; ask them. Most will tolerate it.

 

[staticV3]

Is it safe to connect this or do I risk damaging something?

Depends on the way the soundcard is constructed.

The cable in your picture will short the Lynx's negative output directly to ground, which may result in damage.

To make sure, contact their customer support and ask for the recommended wiring diagram.

 

[DVDdoug]

It's not always safe... Shorting outputs is generally "bad" and should be avoided unless the manufacturer says this kind of adapter is OK.

You probably won't fry the soundcard but there's also a chance of damaging (distorting) the sound when it's connected that way.

I assume your soundcard also has an unbalanced output and I recommend you use it.

Or get another soundcard or the Apple USB dongle which is inexpensive and highly rated.


...Going the other way around, from an unbalanced output to a balanced input is OK. It's OK to short inputs, and you still get some of the noise-rejection benefits of a balanced connection.

 

[Sokel]

It's not always safe... Shorting outputs is generally "bad" and should be avoided unless the manufacturer says this kind of adapter is OK.

You probably won't fry the soundcard but there's also a chance of damaging (distorting) the sound when it's connected that way.

I assume your soundcard also has an unbalanced output and I recommend you use it.

Or get another soundcard or the Apple USB dongle which is inexpensive and highly rated.


...Going the other way around, from an unbalanced output to a balanced input is OK. It's OK to short inputs, and you still get some of the noise-rejection benefits of a balanced connection.

Problem may be that Lynx's breakout cable usually only has balanced I/O.
I wouldn't short Lynx's output so the usual converters may be a solution.

Or another (true,not all are) balanced input amp.

 

[jonwb]

Thanks for your replies. Really appreciate it! Yes the Lynx breakout cable is balanced. I found a Trinnov diagram online and they recommend leaving the XLR Pin 1 unconnected. I can go to my garage and make a similar cable. I don't think this would damage the Lynx? Do any of you?

 

[staticV3]

I found a Trinnov diagram online and they recommend leaving the XLR Pin 1 unconnected. I can go to my garage and make a similar cable. I don't think this would damage the Lynx? Do any of you?

Again: This is device-specific. What works for Trinnov, may well damage your Lynx.

That's why it's usually best to avoid passive XLR->RCA connections altogether.

 

[johny_2000]

RME does not recommend this type of connection: "The XLR line outputs do not operate servo balanced! When connecting unbalanced equipment, make sure pin 3 of the XLR output is not connected. A connection to ground might cause a decreased THD (higher distortion) and increased power consumption!".

In general, you should avoid connecting pin 3 to anything in this case. Otherwise, it will not burn out the XLR output driver for the RME device, but it will seriously degrade the performance of the device.

 

[jonwb]

Ok thanks, so Pin 2 to RCA hot... Pin 1 to ground... Pin 3 not connected

 

[staticV3]

Ok thanks, so Pin 2 to RCA hot... Pin 1 to ground... Pin 3 not connected

Ask Lynx customer support.

 

[johny_2000]

Ok thanks, so Pin 2 to RCA hot... Pin 1 to ground... Pin 3 not connected

One experienced audio engineer said that if they have to use pre-made XLR to unbalanced plug cables, they break off (male) or drill out (female) pin 3 of the XLR plugs to make sure they won't connect. He said this is a better method than re-soldering the plugs, and said that sometimes this happens because of the molded housing of the plugs.

 

[jonwb]

Ok thanks, so Pin 2 to RCA hot... Pin 1 to ground... Pin 3 not connected

.... and the amp blew up!!! Yeah, staticV3 I think I'll email Lynx Monday. This card isn't worth the risk, thanks