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Re: What to do with a problem called Grounding
MMM #415679 11/29/15 01:29 PM
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Can you be specific how you wired your room.

I think you said you did split plugs with a shared neutral. Is this the case?

Send me a pm if you want. You sound fairly competent in electrical, so I'm willing to talk you through the issue on the phone if you want. A lot faster than message tag online. smile

Re: What to do with a problem called Grounding
MMM #415680 11/29/15 01:33 PM
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A nights sleep and you get to think about what you have and what your options are.

Right now it looks like the MCA is going to get boxed up and replaced by something else. The big question is what.

I will give Axiom a call and see if Ian can convince me that their amp is the direction to go.. but the cost vs performance just seems to be a bit too large of a barrier to get over. For the same cost as getting 5 channels from Axiom, I could order in an Outlaw 7 channel amp + Marantz AV7702

There is a local dealer of Emotiva and I could buy into their XPA-7 that would give me 5.1 from the single amp with the extra two channels needed for the LFRs.

For a far less outlay, I could purchase 2 Crown XTi800 to power the LFRs and use the two Amp/One for surround, and center by monoblocking the second unit to get 200w @ 4ohm.

I remember that one of the members here who moved to LFRs went with the Crown amps and didn't have bad things to say about that option. It might be the better choice as the cost is minimal and leaves me some room to look into moving to a newer pre-amp like the Yamaha CX-A5100 in a few years as the room is setup to run 11.2. who knows by then it might be worth while to look in that direction.


Anthem: AVM60, Fosi DAC-Q5
Axiom: ADA1500, LFR1100 Actiive, QS8, EP500, M3, M3comp, M5
Re: What to do with a problem called Grounding
MMM #415681 11/29/15 01:48 PM
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If you have hum from other stuff (TV hdmi) the issue could be a simple electrical reconfigure. smile May cost $0.

Re: What to do with a problem called Grounding
MMM #415682 11/29/15 02:54 PM
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I'm thinking it's your cable TV.


::::::: No disrespect to Axiom, but my favorite woofer is my yellow lab :::::::
Re: What to do with a problem called Grounding
MMM #415684 11/29/15 03:54 PM
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Hi Matt,

I'm sorry to hear that you are still having issues with hum in your system. Just for the record, the Axiom DSP has a three prong plug only for the safety earth connection to the metal chassis as it is not double insulated and hence a safety (and legal) requirement. The signal ground is floating relative to the safety (AC) earth, so it cannot be creating a ground loop in the typical sense. I don't want to question Anthem's design, but I find it very strange that they do not use a three-prong power connector. The reason I find this strange is that high power amplifiers almost always have a safety ground connection. From the photos I can find of the back of the MCA5, it does have CSA electrical approval, but it does not have a double-box double insulated logo on it anywhere. I don't know how this would have passed CSA approval without either having a safety earth connection OR being double insulated. I also find it very strange that they specifically recommend using the XLR inputs over the RCA inputs. Any amplifier that offers both should perform equally well with either input that is offered. None of that is going to help you with your problem, so before you jump to put anything up for sale, there are some simple things that should be tried:

Disconnect all inputs to the AV7005, but leave the DSP and your two power amps in the equation. Hum?

If yes, disconnect the outputs from the AV7005 to your AudioSource amp. Hum?

If yes, remove the DSP and connect FIVE pre-outs from the AV7005 to your MCA5 (maybe use the surround L/R to connect to the LFR rear sections for this test. Hum?

If yes, the MCA5 is the issue. If no, try connecting FIVE RCA pre-outs from the AV7005 (disconnect the XLRs). Hum? If yes, the MCA5 is the issue.

If you do get hum with either of these configurations with no inputs connected to the AV7005 and the DSP out of the loop, try connecting a wire from the ground screw on the back of the MCA5 to the phono ground on the AV7005. See if that changes the hum level at all.

Thanks,

Andrew

Re: What to do with a problem called Grounding
MMM #415685 11/29/15 05:24 PM
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Is the secondary usually connected to chassis ground in electronics? I always thought it was the primary only and the secondary was floating -as in the Axiom amp.

Trying to understand the bonding jumper.

Re: What to do with a problem called Grounding
MMM #415700 11/30/15 02:27 AM
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There is a long standing issue between the MCA and the Axiom DSP. This was discussed for a bit with Andrew last year and if I plug in an RCA cable between the DSP and the MCA with nothing else connected. (ie not even a Pre-Amp hooked up) the MCA generates a ground loop humm. If I used an XLR cable, then that humm was eliminated.

Since those tests, I bought myself another two cheeper amps that I was going to use for surround channels as I got a new pre-amp as I was using a receiver before that has pre-out connectors.

The new amps can be hooked up to the DSP via RCA and they generate ZERO humm. SO I know that the MCA is not playing nice with the Axiom DSP.

I have been playing with the Marantz AV7005 and it has it's own funny quirks. I have a couple mini HTPC boxes that I used to run linux and my KODI and another to run a music media player on. For some reason, these pc's hooked up to the Marantz make funny noises through the speakers when the hard drive or network is accesses. I can take the same pc's and hook them into my old Pioneer receiver and it makes no sound what so ever.

I am now thinking longer term. Simply sell off the AV7005 and MCA5 amp and recoup my money that was spent on them, the theoretical added sound benefit I got from them vs the aggravation and trouble is not worth it. I have the old Pioneer receiver and with the two Amp/One that I have can run the LFR's

I can look into getting a better set of crown amps, or something different in the future. I can sit tight for the time being and just enjoy my music and TV with the old equipment that I have and wait for 2-3 years for Atmos and DTS-X to become common old school or die out replaced by something better and upgrade to them later for hopefully cheep.


Anthem: AVM60, Fosi DAC-Q5
Axiom: ADA1500, LFR1100 Actiive, QS8, EP500, M3, M3comp, M5
Re: What to do with a problem called Grounding
MMM #415711 11/30/15 11:56 PM
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Originally Posted By oakvillematt
... I can sit tight for the time being and just enjoy my music and TV with the old equipment that I have and wait for 2-3 years for Atmos and DTS-X to become common old school or die out replaced by something better and upgrade to them later for hopefully cheep.

No! True Audiopiles not have time for wait and enjoy music. You play cable bingos like Andrew show and make much posts here.

Reflect!


Fred

-------
Blujays1: Spending Fred's money one bottle at a time, no two... Oh crap!
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