[dazzerfong]

  At least it was EMP proof, a good case for tube amps for audio. 

If an EMP does occur, audio would be the last thing on my mind. (Ok, it won't be)
 
I always thought the vacuum tubes were just less sensitive, but would still be fried depending on luck.

 

[analogsurviver]

  At least it was EMP proof, a good case for tube amps for audio. 

At last, something we can agree upon.

 

[MacacoDoSom]

  I use this device as the DAC with my powered studio monitors.  My sources can sometimes be quite noisy when charging (Chromebooks, netbooks, inexpensive laptops, etc), so I always make sure that I have balanced inputs with the pin-1 ground lifted on both XLR outputs.
 
Maybe my brain is wired incorrectly.  Well, I'm almost certain that it is 

, but what setting makes the most sense for lifting the ground to you:  In/Out?
 

 
The Out position would make more sense for Lift, but as I can see it follows the same logic as the MONO SUM, normal Out..., the LIFT position would only be used in certain situations, noise because of ground loops... as the MONO SUM...
You get less noise with the ground lifted?

 

[sonitus mirus]

   
The Out position would make more sense for Lift, but as I can see it follows the same logic as the MONO SUM, normal Out..., the LIFT position would only be used in certain situations, noise because of ground loops... as the MONO SUM...
You get less noise with the ground lifted?

 
It is actually lifted when the switch is in the OUT position.  Though, using similar logic that you mentioned, my first guess was to try it with the switch IN.
 
The story behind this is that I have a pair of powered speakers, and I wanted to use my Chromebook to play streaming audio from a subscription service.  Initially, I used RCA cables from a typical consumer USB DAC, and everything sounded wonderful...until I needed to plug in the Chromebook to recharge it.  When the power cable was plugged into the Chromebook, there was a noisy 60Hz hum that could be heard between songs or when pausing the music.  I tried all kinds of tricks to fix this ground loop, and finally stumbled upon a cheap Peavey USB-P with XLR balanced cables that finally resolved the noise issue.  
 
The Peavey DAC's XLR ground pins are always lifted.  The device does not have particularly wonderful measurements by audiophile standards, with a FR of +/- 1dB from 20-20kHz and THD + Noise <.015% @ 1kHz.  To add to potential problems with sound, it's only 16-bit/48kHz.  All of my streaming music is 16/44.1kHz, and I doubt I could hear a difference if challenged on it, but that was not the worst of my problems.  My biggest issue was that the Peavey only had instrument level output, or about -9 dBu into the speaker's 10k Ohm XLR input.  I listen to my music at quiet levels, and even with the speaker volume at the maximum gain, the sound was not too loud with the pre-amp volume pot at 50% or more.  Consequently, the speakers would automatically shut off after about 30 minutes by design, since the input signal was so low.   That is why I picked up this Radial Engineering USB-PRO device.
 
This Radial USB DAC has true line level output. (actually higher at up to +8 dBu)  It also has much better performance ratings and can autosense my 16/44.1 music without having to convert the sample rate.  Initially that ugly hum was back, but now I have the ground lift button sorted out correctly and the noise is gone again.  The best thing about it is that I was able to turn the volume down on the speakers, and the signal coming into them is much hotter, which means that I no longer have the sound abruptly shut off now.

 

[MacacoDoSom]

 

   
The Out position would make more sense for Lift, but as I can see it follows the same logic as the MONO SUM, normal Out..., the LIFT position would only be used in certain situations, noise because of ground loops... as the MONO SUM...
You get less noise with the ground lifted?

 
It is actually lifted when the switch is in the OUT position.  Though, using similar logic that you mentioned, my first guess was to try it with the switch IN.
 
The story behind this is that I have a pair of powered speakers, and I wanted to use my Chromebook to play streaming audio from a subscription service.  Initially, I used RCA cables from a typical consumer USB DAC, and everything sounded wonderful...until I needed to plug in the Chromebook to recharge it.  When the power cable was plugged into the Chromebook, there was a noisy 60Hz hum that could be heard between songs or when pausing the music.  I tried all kinds of tricks to fix this ground loop, and finally stumbled upon a cheap Peavey USB-P with XLR balanced cables that finally resolved the noise issue.  
 
The Peavey DAC's XLR ground pins are always lifted.  The device does not have particularly wonderful measurements by audiophile standards, with a FR of +/- 1dB from 20-20kHz and THD + Noise <.015% @ 1kHz.  To add to potential problems with sound, it's only 16-bit/48kHz.  All of my streaming music is 16/44.1kHz, and I doubt I could hear a difference if challenged on it, but that was not the worst of my problems.  My biggest issue was that the Peavey only had instrument level output, or about -9 dBu into the speaker's 10k Ohm XLR input.  I listen to my music at quiet levels, and even with the speaker volume at the maximum gain, the sound was not too loud with the pre-amp volume pot at 50% or more.  Consequently, the speakers would automatically shut off after about 30 minutes by design, since the input signal was so low.   That is why I picked up this Radial Engineering USB-PRO device.
 
This Radial USB DAC has true line level output. (actually higher at up to +8 dBu)  It also has much better performance ratings and can autosense my 16/44.1 music without having to convert the sample rate.  Initially that ugly hum was back, but now I have the ground lift button sorted out correctly and the noise is gone again.  The best thing about it is that I was able to turn the volume down on the speakers, and the signal coming into them is much hotter, which means that I no longer have the sound abruptly shut off now.

 
So, they have the picture wrong? Have you read the manual?
 
"The USB-Pro has been designed to minimize hum and buzz caused by ground loops by incorporating dual isolation transformers for the XLR outputs. The isolation transformers are normally bypassed but may be introduced into the signal path using the side access ISO switches. If you hear noise after connecting the USB-Pro to your audio system, try engaging the isolation transformers by sliding the switch in the direction of the arrow.
This is supplemented with a ground LIFT switch located next to the XLR outputs. When set to the inward position, this switch disconnects pin-1 from the two XLR’s."
 

Ground Lift is more a testing thing and it's not the way it should work. You should check  your power supply instead, it should be rectified and it should not introduce noise.
 
I have a similar setup, PC(laptop)->USB powered DAC->Powered Speakers, the laptop is always connected to the mains, NO hums NO noise, with ground lift I get not a hum but a bzzzzz, but if you want your balanced cables to be balanced you should not use the lift position. 

 

[sonitus mirus]

   
So, they have the picture wrong? Have you read the manual?
 
"The USB-Pro has been designed to minimize hum and buzz caused by ground loops by incorporating dual isolation transformers for the XLR outputs. The isolation transformers are normally bypassed but may be introduced into the signal path using the side access ISO switches. If you hear noise after connecting the USB-Pro to your audio system, try engaging the isolation transformers by sliding the switch in the direction of the arrow.
This is supplemented with a ground LIFT switch located next to the XLR outputs. When set to the inward position, this switch disconnects pin-1 from the two XLR’s."
 

Ground Lift is more a testing thing and it's not the way it should work. You should check  your power supply instead, it should be rectified and it should not introduce noise.
 
I have a similar setup, PC(laptop)->USB powered DAC->Powered Speakers, the laptop is always connected to the mains, NO hums NO noise, with ground lift I get not a hum but a bzzzzz, but if you want your balanced cables to be balanced you should not use the lift position. 

 
Yes, I read the manual, it is only a few short pages and a spec sheet.  Not sure how I missed that, but I guess it explains why I am not cut out to be a rocket scientist. 

 
It appears that I do not have the grounds lifted on the balanced outputs, and I verified that the isolation transformers were NOT engaged.  I think.  In this picture, looking at the left side of the unit, I see "RIGHT-ISO >" and "LEFT-ISO >".  I have the 2-position switches set opposite of the direction the arrows are pointing toward.  I hope this means that they are not enabled, as my goal was to remove the transformers that fudge with the frequency response.  It was the reason why I opted to try this new device over the Peavey USB-P, which also uses transformers in a similar design.
 

 
 
The transformer isolation with the Radial device significantly impacts the frequency response, and is suitable for a PA system, but not something that I want to employ with my powered speakers.
 

 
 
Maybe the sound with the pins lifted was more of a buzzzzzz. Using the same gear with my headphones and various other amps and DACs did not produce this noise.  It was only when using the powered speakers, and then only when this specific Chromebook was plugged in.  I had 3 other chargers that I tested, all with the same results.  I don't have the option to change the speaker power, but I did try different power cables, and every plug/power combination to try and solve what I understood to be a ground loop issue.  I was going to return the speakers as being defective until I switched from RCA to balanced XLR with that Peavey device.  Since that fixed the problem, I assumed it was the lifted ground that was responsible. 
 
I apologize to everyone as this really does not belong in this particular thread, and I will take this elsewhere if anything more needs to be discussed.  Anyway, I listened to music all night with the ground lift button in the outward position and the transformers disengaged, and there was no background noise between songs or when the music was paused, only dead silence even with the volume turned WAY up.  Back to the music.

 

[MacacoDoSom]

I have some Focal Alphas with a Roland Quad-Capture with balanced connections and as I said no noise, as they don't have a volume button the volume is controlled in the DAC and no noise, with the ground lifted I get a low (in volume) and constant bzzzzzzzz, even with the laptop shutdown (and the DAC as it's usb powered) if I disconnect the usb cable the noise changes to higher hummm, just like a live cable connected to an amp, in this situation if I change the ground to normal (grounded) no noise whatever, as expected....
It's not a good idea to un-ground a balanced connection, I think that a switch to lift the ground is more for a diagnosis purpose than a solution....
 
You had it right after all, that is why it solved your no-problem, that box seems pretty good... and as someone said the solution to most of the problems it to RTFM.....(with pro gear anyway).

 

[arnyk]

  At least it was EMP proof, a good case for tube amps for audio. 

 
Being tubed does not automagically confer EMP resistance on it.
 
Back in the day the standard for EMP resistance was called TEMPEST, and if you were a tech and had the chance to examining TEMPEST rated gear, you saw that there was a lot more to it than being tubed. In fact, a lot of it was wall-to-wall SS. 
 
A little light reading:
 
 http://cryptome.org/emp.htm
 
 http://fas.org/nuke/intro/nuke/emp/c-6body.pdf
 
 
 
Fact is that the EMP resistance of tubed gear was just another tube bigot myth. 

 

[sonitus mirus]

  I have some Focal Alphas with a Roland Quad-Capture with balanced connections and as I said no noise, as they don't have a volume button the volume is controlled in the DAC and no noise, with the ground lifted I get a low (in volume) and constant bzzzzzzzz, even with the laptop shutdown (and the DAC as it's usb powered) if I disconnect the usb cable the noise changes to higher hummm, just like a live cable connected to an amp, in this situation if I change the ground to normal (grounded) no noise whatever, as expected....
It's not a good idea to un-ground a balanced connection, I think that a switch to lift the ground is more for a diagnosis purpose than a solution....
 
You had it right after all, that is why it solved your no-problem, that box seems pretty good... and as someone said the solution to most of the problems it to RTFM.....(with pro gear anyway).

 
It is a common feature for a DI box to have a ground lift, and these are safe to use.  This is not used strictly for testing.  It seemed that in the end my solution was using balanced cables instead of the unbalanced RCA cables, though my first DI box had permanently lifted grounds and isolation transformers while I most likely required neither of these options to eliminate the hum.
 
http://www.soundonsound.com/sos/1997_articles/feb97/diboxes.html

The other common (but much less sinister) electrical problem is that of ground or earth loops. These can be caused when a loop is formed (via a connecting audio lead) between the earth in your mixer's mains plug and the one in an instrument's mains plug (to take one example). In this situation, 'earth currents' circulate, resulting in a hum that should be familiar to most people. Unfortunately, a lot of musicians cure this problem by removing the earth lead from their mains plug, which is a potentially lethal thing to do. The best solution is to disconnect the screen at one end of the audio cable, breaking the loop in a much safer way. Most DI boxes have a switch labelled 'Ground Lift', or something similar, and these simply disconnect the screen from the balanced mic-level signal going to the mixer, so that the mixer's earth is isolated from the instrument/amplifier earths (since the audio signal is balanced through the transformer, the screen is not needed for the return signal).

 

[StanD]

   
Being tubed does not automagically confer EMP resistance on it.
 
Back in the day the standard for EMP resistance was called TEMPEST, and if you were a tech and had the chance to examining TEMPEST rated gear, you saw that there was a lot more to it than being tubed. In fact, a lot of it was wall-to-wall SS. 
 
A little light reading:
 
 http://cryptome.org/emp.htm
 
 http://fas.org/nuke/intro/nuke/emp/c-6body.pdf
 
 
 
Fact is that the EMP resistance of tubed gear was just another tube bigot myth. 

Sheesh, it was a joke. Unfortunately it can only encourage our resident CD Mat expert.

 

[analogsurviver]

  Sheesh, it was a joke. Unfortunately it can only encourage our resident CD Mat expert.

And now try to tell me that SS is inherently as (or even more...) EMP resistant than HSD ( Hollow State Device ) ...

 

[cel4145]

Can your CD mat survive this?




Speaking of CD mats



Gotta love that marketing prose!

 

[Exacoustatowner]

IS that  "SID" from the Brilliant Pebbles Website? He offers a TONGUE-IN-CHEEK product like that. 
 
Quote:

Can your CD mat survive this?




Speaking of CD mats



Gotta love that marketing prose!

 

[cel4145]

IS that "SID" from the Brilliant Pebbles Website? He offers a TONGUE-IN-CHEEK product like that.

I don't think so. It's available for sale multiple places:
http://www.amazon.com/Sound-Improvement-Disc-SID/dp/B0030GVDP2
http://highend-electronics.com/products/sid-sound-improvement-disk?variant=960295875
http://www.analogueseduction.net/system-tune-up-and-upgrades/sid-sound-improvement-disc.html

 

[Exacoustatowner]

I don't think so. It's available for sale multiple places:
http://www.amazon.com/Sound-Improvement-Disc-SID/dp/B0030GVDP2
http://highend-electronics.com/products/sid-sound-improvement-disk?variant=960295875
http://www.analogueseduction.net/system-tune-up-and-upgrades/sid-sound-improvement-disc.html

Oh wow. "It give more air between my instruments…" I think "a veil" has been lifted!