Marantz AV7005 Networking A/V Processor Review

[AcuDefTechGuy]

Quite frankly, the marantz looks better. I'd rather buy the Lexicon RX-7 - the overpriced version of the same amplifier that sure does look nice.

Now if its' going in a hidden rack it doesn't matter. But underneath the TV? I'd sacrifice some 160 watts for pretty curvy sides

Hey, some of us just happen to prefer that manly "military-tough-HUMMER" look, okay?

S--------H-------O---------O--------T.

 

[04rex]

Ok, so how do i avoid/fix the problem if it happens?

 

[TLS Guy]

Ok, so how do i avoid/fix the problem if it happens?

Read this thread for a start!

 

[Rickster71]

Now grounding is a huge problem, especially when you have a rack.

The issue is that some units are double insulated and others three pin mains leads.

Now, you have a lot of options, once you mount a unit like the Marantz in question in a rack. It will ground the case to the rack. Now what do you do with other rack mounted units? They will ground through the rack. So what do you do with the mains lead ground, lift it or not? Usually trial and error here.

What about units not in the rack. Do you ground the chassis of those double insulated units to the rack or not? Then if you do, do you lift the mains grounds or not?

So whether a unit hums in a given situation depends to a very large degree on how the units ground plane is configured. And this leaves out house wiring and grounding issues, add them in and you have a real witches brew.

I found the house grounding, including antennas, TV feeds, and phone issues have to be considered in the whole design package.

I couldn't agree more.
It can be a real mess; and I'm sure confusing to many.
The dilemma is that solving noise problems is an art within itself.
There's a certain amount of resistance between all grounds. That resistance can change with humidity, temperature, connected equipment and many other variables.

 

[04rex]

So is this something that is pretty much guaranteed to happen with this specific set up?

 

[TLS Guy]

So is this something that is pretty much guaranteed to happen with this specific set up?

Not guaranteed either way. You need to be aware of grounding issues, and try and avoid ground loops. You need to have a plan to analyze and deal with them when you run into them. We all encounter them.

The issue is, you never want to leave a circular loop between grounds. They all need to flow away from a pre determined point, like rays from a star,

 

[Cos]

In my case I guess I was really lucky, or given the fact I had an anthem pre/pro paired with anthem amp reduced my chance of having issues.

I have been going back and forth with Martantz and Anthem just to figure out how I can ground the two units safely. Granted I read your post, and TBH that is overkill for my setup.

If its just pre/pro and amp having the issue, I was potentially looking at replacing the Marantz AV7005 w/ the Integra DHC 80.2 Pre/Pro with my Anthem PVA 7. the Integra has a ground loop screw and so does my PVA 7. I am actually going to demo the Integra unit first to see how it goes. Since I am about 80% HT 20% music, I dont think there will be much of a difference and the intergra has the 32bit version of the room correction.

 

[AcuDefTechGuy]

I am actually going to demo the Integra unit first to see how it goes. Since I am about 80% HT 20% music, I dont think there will be much of a difference and the intergra has the 32bit version of the room correction.

Even if you are 100% music & 0% HT, in Direct modes there will be no difference in sound quality among the Martantz, Anthem, and Integra.

If you use room corrections or other processing/DSPs, then there will be a difference.

 

[AcuDefTechGuy]

Ok, so how do i avoid/fix the problem if it happens?

The best solution is to do what TLS Guy has documented.

But for quick fixes:

Do you have a satellite or cable line in your system? If so, you can get an RF ground loop isolator. This is exactly the one I bought and it completely eliminated the very loud hum when I hooked my Denon to the AT3005 amp:

http://www.amazon.com/VSIS-EU-Cable-Ground-Loop-Isolator/dp/B0017I3K9M/ref=sr_1_1?ie=UTF8&s=electronics&qid=1298040653&sr=8-1

For interconnect RCA cables, you can get this:

http://www.amazon.com/Raptor-GL15-Ground-Loop-Isolator/dp/B0009O19LQ/ref=sr_1_1?s=electronics&ie=UTF8&qid=1298040756&sr=1-1

Even though it worked perfectly for me and some other folks, it is still not a guarantee!

That is why you should buy directly from amazon. If they don't work, you can easily return them to amazon for free (pre-printed UPS or USPS return labels).

 

[TLS Guy]

The best solution is to do what TLS Guy has documented.

But for quick fixes:

Do you have a satellite or cable line in your system? If so, you can get an RF ground loop isolator. This is exactly the one I bought and it completely eliminated the very loud hum when I hooked my Denon to the AT3005 amp:

http://www.amazon.com/VSIS-EU-Cable-Ground-Loop-Isolator/dp/B0017I3K9M/ref=sr_1_1?ie=UTF8&s=electronics&qid=1298040653&sr=8-1

For interconnect RCA cables, you can get this:

http://www.amazon.com/Raptor-GL15-Ground-Loop-Isolator/dp/B0009O19LQ/ref=sr_1_1?s=electronics&ie=UTF8&qid=1298040756&sr=1-1

Even though it worked perfectly for me and some other folks, it is still not a guarantee!

That is why you should buy directly from amazon. If they don't work, you can easily return them to amazon for free (pre-printed UPS or USPS return labels).

One correction. You can not use a ground loop isolator with satellite systems, because of phantom powering issues. Also the isolators to not pass the control signals to the multiswitch.

For satellite systems you have to strongly bond the ground to the house ground. To do that the installer must make sure the cables enter the house less than 20 ft from the house ground. There is no other way.

The RCA isolator is a transformer and will degrade SQ, especially bass. It will stop hum.

Those solutions are not really the high road though.

If you think about your ground paths logically, you will get out of trouble.

 

[GranteedEV]

I've had a ground loop too. my TV when plugged into the same outlet as the sub amp creates a light 60hz buzz. tbh I've given up on solving it... I'm sure i could but it's such a hassle for something you only hear up close.

 

[TLS Guy]

I've had a ground loop too. my TV when plugged into the same outlet as the sub amp creates a light 60hz buzz. tbh I've given up on solving it... I'm sure i could but it's such a hassle for something you only hear up close.

Let me take a guess. The sub is a two prong lead and the TV is three.

 

[PENG]

I've had a ground loop too. my TV when plugged into the same outlet as the sub amp creates a light 60hz buzz. tbh I've given up on solving it... I'm sure i could but it's such a hassle for something you only hear up close.

Same here, if I can only 'detect' any hum when within an inch from the mid range driver I would leave it alone. I strongly believe even those who reported their previous gear had no hum, I think either they luck out to have that amp and preamp chassis at the same potential or they weren't simply looking/hearing hard for it. The only other way would be to do what TLSGuy did but that is a lot of work and require in depth knowledge in noise issues and grounding schemes. It is not something that anyone should do.

 

[Warpdrv]

But why exactly would 1 piece of gear have such a pronounced hum and another not.... I have been through my ground loop hum problems and switching power for some devices to another circuit, which I have 6 fixed it for me...

I think it was an issue of making sure that the problematic pieces of gear were mated together or separated if one of the legs was out of phase in the breaker box....

I moved the breakers around in the breaker box to get most of the gear all on the same legs to keep them in phase. http://en.wikipedia.org/wiki/Distribution_board

 

[GranteedEV]

Let me take a guess. The sub is a two prong lead and the TV is three.

no, the tv is a 3-pronged lead and the sub uses a 3-prong lead pro amp. the only wire connecting the tv to anything is a singly HDMI cable to the Marantz receiver (which IS chassis-grounded). It's possible the loop is at the receiever and simply being amplified by the pro amp. But yea, like peng said, since you have to put your ear up against the driver to hear it, iy's just not worth exploring

 

[PENG]

But why exactly would 1 piece of gear have such a pronounced hum and another not.... I have been through my ground loop hum problems and switching power for some devices to another circuit, which I have 6 fixed it for me...

I think it was an issue of making sure that the problematic pieces of gear were mated together or separated if one of the legs was out of phase in the breaker box....

I moved the breakers around in the breaker box to get most of the gear all on the same legs to keep them in phase. http://en.wikipedia.org/wiki/Distribution_board

Everything on the same phase always help but some people claimed that they were getting hum even when the preamp and the amp are plugged into the same wall outlet and have nothing else connected except for the speakers. To me if the hum is audible from a few inches away with volume at below 0 then there is something wrong. But again, if you have to turn the volume way up pass 0, with the souce player turned on but not playing anything, put your ear on the grille, then you are going to hear at least a faint hum. In that case, the amp is working hard amplifying the noise for you. I suspect sometimes when people report hearing hum that's probably what they did, they just upgraded their gear, expect total silence but instead they found some faint hum under extreme condition.

 

[AcuDefTechGuy]

But why exactly would 1 piece of gear have such a pronounced hum and another not.... I have been through my ground loop hum problems and switching power for some devices to another circuit, which I have 6 fixed it for me...

I think it was an issue of making sure that the problematic pieces of gear were mated together or separated if one of the legs was out of phase in the breaker box....

I moved the breakers around in the breaker box to get most of the gear all on the same legs to keep them in phase. http://en.wikipedia.org/wiki/Distribution_board

So this hum is NOT due to a cable RF line being in the same room?

I wonder what is the max volt on the Marantz AV7005.

The reason I ask is because some components (unlike amps and computers) don't have that much voltage/power to require a 3-prong plug - they don't require that 3rd ground plug.

In this case, you could use a cheater plug - a 3-prong-to-2-prong adapter, which costs $2 at Wal-Mart.

Thus, the Marantz pre-pro would no longer be grounded and the hum would be gone.

But we need to know what is the max voltage on the Marantz AV7005.

I've read on the Orion forum that the Orion active crossover has a maximum voltage of only 5 volts, which is considered harmless. So some people are using a 3-prong-to-2-prong adapter to "lift" the ground of the crossover to eliminate the ground loop hum.

 

[AcuDefTechGuy]

True 3-prong?

PENG asked me to hook up my Denon 5308 to my Denon DVD-3800BD to ATI AT3002 amp with all ANALOG unbalanced cables, put in a CD in STOP mode, and set the AVR5308 volume to max +18dB and see if I can hear hum with my ear pressed against all the drivers on the speakers.

I did and could not hear any kind of hum whatsoever, even with my ears against the drivers.

Then PENG asked if the 5308 were truly a 3-prong.

I looked and saw that NEITHER the AVP-A1 nor the AVR5308 has a TRUE 3-prong (3-prong on both ends)!!!

They both have a 3-prong plug for the wall outlet, but the other end, which is connected to the unit, is only 2-prong!

Does that mean neither one of them are GROUNDED?

 

[PENG]

I just measured the potential differences between some of my amps, AVR, prepro etc., as expected, the phantom voltages are all over the map. It is not going to be easy to totally eliminate hum. If someone who has double insulated gear interconnected with unbalanced cables and hear no hum at maximum gain when amplifying noise only, then I would not know why. To me that would defy physics.

 

[PENG]

PENG asked me to hook up my Denon 5308 to my Denon DVD-3800BD to ATI AT3002 amp with all ANALOG unbalanced cables, put in a CD in STOP mode, and set the AVR5308 volume to max +18dB and see if I can hear hum with my ear pressed against all the drivers on the speakers.

I did and could not hear any kind of hum whatsoever, even with my ears against the drivers.

Then PENG asked if the 5308 were truly a 3-prong.

I looked and saw that NEITHER the AVP-A1 nor the AVR5308 has a TRUE 3-prong (3-prong on both ends)!!!

They both have a 3-prong plug for the wall outlet, but the other end, which is connected to the unit, is only 2-prong!

Does that mean neither one of them are GROUNDED?

Yes, that means neither one of them are grounded. And that means there will be phantom voltages (potential differences) between either one of them and the amp it is connected to. That would then result in unintended "ground loop" current. That may be minute if Denon and ATI both managed to keep any capacitive coupling really really low but at +18, such minute signal may, and should still get amplified to an audible level. Again, in my case if I move my ears even a couple inches away I could hardly hear anything. Different speakers may also have different sensitivities to such noise. For example, my center speaker was almost silent in this experiment.

You really have a superb system if you could not hear anything at +18 with ear on driver. Absolutely amazing! Perhaps your DefTech is doing the magic for you. I would be interested in owners of those highly sensitive Klipsch speakers to do the same experiment and let us know if their systems are also silent at maximum gain, +18 dB for Denon and Marantz (probably Onkyo as well), using analog inputs with CD or DVD player turned on but not playing anything disc.