I think the looping feedback he is referring to MAY (or may not) still happen via the neutral path…
Ask Tom V of PSA if you were to add the iFi Groundhog, if there are any dangers or risks (I doubt it). You would need to find a vacant RCA connector on the sub to use for grounding.
OR ask PSA if there’s a cheaper/simpler way to ground his subwoofer.
Nothing to lose in asking the question.
Wow! Not even trying. Speechless
Thats a little harsh, dont you think? Peter has been very active in trying to find the reason to the issue.
And he also suggested using RCA with Y-splitters to connect both the subs and PowerAmp at the same time. Have you tried this approach?
I’d say very few component manufacturers would endorse using both balanced and single ended outputs at the same time as this can be troublesome. (Even though i am using the exact same config myself)
Is there a specific reason for you wanting to drive the power amp directly from the Lumin? (I.e. without the preamp)
Well, to be clear, my “not even trying” comment was NOT directed to @wklie (Peter). It was directed to his support team. I know Peter tried a lot for me and appreciate it a lot. But this was the time that he had to consult with his support team, and came back with his findings.
I am not going to use an Y cable for both Amp and subwoofers. I paid quite a bit of money for my system, Lumin T1 included, and I am not going to use inferior cables and connection with this high price system. I believe in good cables (my XLR cables are $300 a pair) and I am not going to change this. I also prefer XLR vs. single ended RCA.
Back to troubleshooting:
With subwoofers removed, I connected Lumin to Amp via RCA cables. I remembered I had done this before. Hum was still there, albeit reduced in half.
So there is an issue with the RCA connections on my Lumin unit.
Which means that my options now are:
1 - Exchange the Lumin.
2 - Get the preamp
I am wary of #1, as the new unit may have the same issue by design. So, I am picking the path of least resistance, and getting myself a preamp - Parasound Halo P5
Pre-amp is a good idea, for it’s analogue volume control.
Exactly! I was doing a lot of research on adding a preamp to Lumin anyway. So it was coming perhaps, just trying to save a bit of money. Now I am forced to. Oh well… Thanks Sean!
We retested Lumin S1 / A1 / T1 RCA direct output to an Ayre power amp successfully with no hum.
However, it does not mean your unit is faulty. There are many reasons for hum, such as ground loop, impedance mismatch, polarity, etc.
It does look like you’ll need to get a pre-amp.
May be I’m little late to discussion regarding on ground loop but the first rule of thumb; the grounding must only happens in the lowest impedance point. In any HiFi system, the lowest impedance is always the power amp. That’s where, it carries the high current path. Any ground loop occurred at the source will cause excessive hum. Therefore, it is important never to have any form of ground (Earthed) connected to the source, preamp. Only the power amp should be connected to ground. As long all components are connected one another through audio interconnects, all we see the ground at the power amp side.
The best way is to use the multimeter, check all the source components that are electrically earth isolated. Hope this helps.
Understood. Thank you.
I was thinking about getting a preamp anyways, we talked about this privately. I have a Parasound Halo P5 on order.
I appreciate your help
@MusicEar
I do not agree. Every part in the chain can be grounded, no problem. Just use the multimeter (or pole checker) to make sure you have the power plugs aligned correct (Live an Neutral).
Unhook everything, just the ‘naked’ box (interlinks, speakers, everything out).
set multimeter for Volt
Plug in 1-by-1, check for current between the housing and ground, plug in the other way, check again.
Select the lowest current position.
I like it a lot. That is without subs, as when having the subs connected the hum bothers me. Once the preamp arrive, I should be really able to tell. Definitely a keeper!
Parasound Halo P5 arrived. No hum. Dead silent. Happy!
You may now proceed to burn in the Lumin 7x24 for two weeks or more, using a variety of PCM sample rates and DSD in repeat mode, with the pre-amp turned on (turn off power amp if necessary).
After a day or so with the Parasound Halo P5 added to the chain, here are my thoughts:
1 - When adding the P5 to the chain (just for analog volume control, XLR out from Lumin T1 to P5), there is a very noticeable improvement
2 - The sound is more “organic” and “fuller”. There is a more “analog” feeling to it. When Lumin was directly connected to the Amp, the sound was a bit digital and thin.
3 - I also love the bass management on P5, as well as crossovers on it for both subwoofers and mains. Great volume control and remote too.
Yes, in most cases people find that the sound quality is better with a pre-amp than without - this does not only apply to Lumin but to many sources as well, including CD players.
