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Pass aleph Ono - OK to run both xlr and rca output?
Pass aleph Ono - OK to run both xlr and rca output?
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Old 9th January 2020, 10:59 PM   #1
recstar24 is offline recstar24  United States
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Default Pass aleph Ono - OK to run both xlr and rca output?

Hello! Apologize as this is coming from just a normal consumer and not a DIYer, nor did I want to bother Nelson by email, so I’m hoping to get a quick answer to the above. My aleph ono is connected xlr to my preamp, and I’m wanting to connect a headphone amp to the rca output. I’m guessing it’s ok because the balanced output is run from a completely different stage that creates the inverted signal, but figured I’d double check with the experts. Thank you!

Last edited by recstar24; 10th January 2020 at 03:15 AM.
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Old 9th January 2020, 11:20 PM   #2
Zen Mod is offline Zen Mod  Serbia
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Pass aleph Ono - OK to run both xlr and rca output?
just do it
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Old 10th January 2020, 03:59 AM   #3
recstar24 is offline recstar24  United States
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just do it
Done
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Old 14th January 2020, 03:55 AM   #4
recstar24 is offline recstar24  United States
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Quick follow up question - from the rca out, the sound is heavily distorted, unless i also have the preamp turned on connected to the xlr, then it plays fine. The rca out will only play cleanly if the the device that is also connected to the xlr is also turned on, any ideas on why that is?
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Old 14th January 2020, 04:04 AM   #5
rayma is online now rayma  United States
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The connected circuitry is unpowered, and becomes a nonlinear load on the outputs.
If you add internal series resistors to the XLR outputs (one for each phase), that should
isolate the problematic load enough to eliminate the distortion. Try 2k to start.
The RCA outputs may also need resistors if there is also the reverse problem.

Last edited by rayma; 14th January 2020 at 04:27 AM.
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Old 14th January 2020, 04:26 AM   #6
recstar24 is offline recstar24  United States
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Quote:
Originally Posted by rayma View Post
The connected circuitry is unpowered, and becomes a nonlinear load on the output.
If you add internal series resistors to the XLR outputs (one for each phase), that should
isolate the problematic load enough to eliminate the distortion. Try 2k to 5k.
Thank you - so it appears that when I’m listening from the rca out, turning on the preamp connected to the xlr presents enough of a load to eliminate the distortion. I’m pretty sure that the xlr output shares its + signal with the rca output as well, but still unsure of why that would lead to the xlr being actively on in order to get clean output from the rca.

Edit: just saw your recent edit. There is no issue going the other way - the xlr to preamp plays perfectly with the rca connected headphone amp turned off. Distortion is only heard on the rca output when the xlr connected device is off.
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Old 14th January 2020, 04:28 AM   #7
rayma is online now rayma  United States
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Originally Posted by recstar24 View Post
still unsure of why that would lead to the xlr being actively on in order to get clean output from the rca.
Think of the XLR load as more like a diode when unpowered. It will cause distortion because
the phono stage cannot drive it well enough. If the load were a tube circuit instead of ss,
there would not be such a problem with the tube off, since the load would just be a large resistor.

What is your XLR connected device?

Last edited by rayma; 14th January 2020 at 04:35 AM.
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Old 14th January 2020, 05:01 AM   #8
recstar24 is offline recstar24  United States
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Quote:
Originally Posted by rayma View Post
Think of the XLR load as more like a diode when unpowered. It will cause distortion because
the phono stage cannot drive it well enough. If the load were a tube circuit instead of ss,
there would not be such a problem with the tube off, since the load would just be a large resistor.

What is your XLR connected device?
Thank you for the excellent explanation. The XLR connected device is a wyred4sound mPre preamp.
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Old 14th January 2020, 07:26 AM   #9
Zen Mod is offline Zen Mod  Serbia
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Pass aleph Ono - OK to run both xlr and rca output?
just keep them ON both

that was my premise - if both downstream connected gadgets are decently made , no problem..... and that you need them both in same time
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Old 14th January 2020, 08:12 PM   #10
recstar24 is offline recstar24  United States
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Quote:
Originally Posted by Zen Mod View Post
just keep them ON both

that was my premise - if both downstream connected gadgets are decently made , no problem..... and that you need them both in same time
Got it - you originally said just do it, I should have specified if both need to be on lol. Everything is A-OK.
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