Marantz AV7005 Networking A/V Processor Review

[AcuDefTechGuy]

Yes, that means neither one of them are grounded.

Isn't this dangerous?

I thought both the AVP-A1 & especially the AVR-5308 would be grounded with that much power inside of them (150watts x 7 ch)???

So does the Marantz AV7005 have a 3-prong on both ends or just one end?

 

[PENG]

Isn't this dangerous?

I thought both the AVP-A1 & especially the AVR-5308 would be grounded with that much power inside of them (150watts x 7 ch)???

So does the Marantz AV7005 have a 3-prong on both ends or just one end?

No it isn't dangerous as long as they are considered double insulated and I am sure they are, otherwise they would not have UL/CSA/NRTL kind of approvals. My AV7005 has 3 prongs on one end only but it is both UL and CSA approved.

Of all my amps/preamps/prepros, only the Bryston is grounded.

By the way you are not going to believe it, subjectively I am beginning to feel the Marantz is giving me a better sound. I can define better a little better later, may be tomorrow.

 

[AcuDefTechGuy]

By the way you are not going to believe it, subjectively I am beginning to feel the Marantz is giving me a better sound.

I'll believe that the day you believe my BP7000SCs sound better than your beloved B&W 802D.

 

[PENG]

Before I log off, I would like to emphasize that there is nothing wrong with the double insulated instead of the grounded scheme. I am only pointing out that with the double insulated scheme, while it may have succeeded in eliminating major ground loop related hum, it cannot avoid a minute ground loop current that is inherent in such design. I think TLSG might have already touched on this topic in some of his earliest posts.

It would appear that whether you could hear the resulting slight hum or not, depends on the potential differences between the equipment that are connected together, the types of interconnects used, the characteristics of the speakers, the amplifer gain (volume position) and the owners sensitivities to that kind of noise. I tend to believe the probability of someone being bothered by or even aware of such hum is extremely low and most of those who became aware of the hum could be because they looked and listened hard for it.

 

[PENG]

I'll believe that the day you believe my BP7000SCs sound better than your beloved B&W 802D.

Excellent memory! You should be a perfect candidate for DBT.

 

[AcuDefTechGuy]

No it isn't dangerous as long as they are considered double insulated and I am sure they are, otherwise they would not have UL/CSA/NRTL kind of approvals. My AV7005 has 3 prongs on one end only but it is both UL and CSA approved.

But before I bought the RF ground loop isolator, I got this very loud hum noise on my system, which led me to believe that the 5308/AVP-A1 are both grounded?

At any rate, since "not-grounding" is pretty safe, unless the wires come loose or something, then I say try a $2 cheater plug and see if that eliminates the hum 100%!

 

[PENG]

But before I bought the RF ground loop isolator, I got this very loud hum noise on my system, which led me to believe that the 5308/AVP-A1 are both grounded?

I agree with you that if your pre and amp are double insulated instead of grounded then those $2 cheater plug won't do anything for you.

Since you bought a RF ground loop isolator, that is not a cheater plug so I need to know what kind of RF ground loop isolator you bought and installed in order to speculate what caused your loud hum to start with.

At least now that I know you did have a hum before adding the isolator I am less confused. Still, I can't believe you could max your volume with ear on driver failed to detect any hum. As I said before, that would have defied physics.

I believe you could not hear any hum/noise in the experiment you did for me and I would pay to hear it for myself. I am just trying to find an explanation for it. How quiet is your room? In mine, if my furnace is on I wouldn't be able to hear the hum either.

At any rate, since "not-grounding" is pretty safe, unless the wires come loose or something, then I say try a $2 cheater plug and see if that eliminates the hum 100%!

I would not say that at all. "Not grounding" with that 3rd ground pin is only okay if the equipment is designed for it, built by the manufacturer and has satisfied the regulatory requirements such as UL approval in the US and CSA approval in Canada. In the US there may also be other additional requirements depending on the states. Once again, one should not remove the use of the ground pin from a piece of equipment/device that comes with it.

 

[TLS Guy]

I agree with you that if your pre and amp are double insulated instead of grounded then those $2 cheater plug won't do anything for you.

Since you bought a RF ground loop isolator, that is not a cheater plug so I need to know what kind of RF ground loop isolator you bought and installed in order to speculate what caused your loud hum to start with.

At least now that I know you did have a hum before adding the isolator I am less confused. Still, I can't believe you could max your volume with ear on driver failed to detect any hum. As I said before, that would have defied physics.

I believe you could not hear any hum/noise in the experiment you did for me and I would pay to hear it for myself. I am just trying to find an explanation for it. How quiet is your room? In mine, if my furnace is on I wouldn't be able to hear the hum either.




I would not say that at all. "Not grounding" with that 3rd ground pin is only okay if the equipment is designed for it, built by the manufacturer and has satisfied the regulatory requirements such as UL approval in the US and CSA approval in Canada. In the US there may also be other additional requirements depending on the states. Once again, one should not remove the use of the ground pin from a piece of equipment/device that comes with it.

Peng, this was the post: -

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-...8040653&sr=8-1

For interconnect RCA cables, you can get this:

http://www.amazon.com/Raptor-GL15-Gr...8040756&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).

This was what he used for his cable TV.

That is an inline 75 ohm transformer.

The fact that it worked means his cable system is not installed to code. The cable system is not tied to the house ground at entry as it should be.

So why does a transformer interrupt a ground loop? Here is a schematic for a transformer. A ground loop isolator would be a 1:1 transformer like A in the picture below.

So on one side the signal goes through a coil (primary) wound round an iron core. This core also has another coil wrapped round it (Secondary). The primary induces a signal in the secondary by electromagnetic induction, that sends the signal to the receiving device. In an isolating transformer the primary and secondary coil have the same number of turns (1:1). So the voltage at input and output is the same.

Now it works because as you can see the ground and signal path are totally interrupted. There is no electrical connection, only a magnetic one.

Now this works for an antenna, or cable system as there is no DC signal.

It will NOT work for a satellite system, as it will not pass the DC phantom powering voltage or the control signals up to the roof detector and multiswitch.

So you have to ground a satellite system properly. Now TV signals are very high frequency and that a cheap transformer can handle just fine.

Audio signals are another matter entirely.

This is the device he recommends for audio isolation.

Another 1:1 transformer. However we have signals all the way to 20 Hz. A cheap transformer like that will seriously degrade SQ. It will act as a high pass filter and introduce hysteresis distortion to boot.

A cheap transformer like that, or for that matter any transformer should not be put in an audio signal path, with the exception of high quality microphone transformers, or the output transformer of a tube amp. Even then the output transformer of a tube amp is probably its biggest limitation.

That is not the correct solution for eliminating ground loops in line level feeds of audio systems.

 

[PENG]

Peng, this was the post: -



This was what he used for his cable TV.

That is an inline 75 ohm transformer.

That explains why he had that loud hum and got it fixed but I still don't understand how his ungrounded prepro and amp with obviously many other things interconnected would not have an audible hum with volume at +18. I can almost guarantee any digital multimeter will reveal those phantom (capacitive coupling) potential differences between his many equipment chassis with the interconnects removed. So I am pretty certain his interconnects would have to carry some sort of loop currents. I specified digital meter because but you and I should both know why an analog (e.g. AVO) meter would likely not show those voltages so we don't need to go there.

I realized that such loop currents would be extremely low but at +18 volume I still would expect an audible (though could me barely audible) hum. This is simple physics/electrical theory. I have that kind of very low level hum in all my systems, now and in the past, and in other people's systems. I also have no trouble accepting such extreme low level noise because it is really far from being audible in normal listening environments. To do what you have done to your system is too much work for me for so little gain so I am not going to climb that tree.

My point is simply that how could he has a silent system, without doing what you did?. Further, his system obviously was not inherently immuned to ground loop original noise to begin with, as the cable TV thing did cause loud hum.

Now I can't wait to hear your theory, again specifically about a speculative explanation of his silent system without really managing those phantom potential differences inherent in the unground systems.

 

[PENG]

I have been playing with my new toy for a few days now and my preliminary impression is that it is an excellent value for anyone who is interested in an entry level separate system. When I say entry level I refer to price point only, not necessarily sound/video quality, specs and features related. Since the Marantz system replaced my previous Denon AVR-4308 based system, I tend to compare it with the Denon a lot but any reference to their sound and video quality will not be reliable as it is subjective and done by memory only.

Hardware & Features

To me, the Marantz pairs focussed on things that really count for me, in terms of sound quality anyway. For example, the AV7005 skips any gold plated, high quality unbalanced RCA connectors, while providing balanced I/O connectors. The RCA connectors seem a little delicate, they don’t provide tight fit for some of my interconnects but surprisingly my lower cost Philips interconnects do fit tight in them. The 4308 definitely has more robust and better quality connectors.

The Marantz remote is easier to use but it is not very sensitive and the delay seems a little longer compared with Denon’s.

The power transformer looks exactly like the toroidal one in the MM8003 but Marantz claimed (it could still be a mistake but unlikely) it is an EI core type with a round cover for shielding. Either way, it is just another example that shows Marantz is serious about potential electromagnetic interference that may adversely affect sound quality.

The pre-pro tuner offers only 5 HDMI at the back while most mid range AVR by Yamaha, Onkyo and Denon offer at least 6 if not 7 or 8. This is an example of how they save money on things that don’t affect SQ. While the 4000 series Denon models have dual 32 bit DSSs, the Marantz has just one. That may be the reason, or one of the reasons why the 7005 cannot run Audyssey on top of 24/192 kHz HD sound codec. It also does not offer Audyssey MultiEq XT32 but the plain XT. This Marantz comes with the Audyssey Dynamic EQ and volume features. I have no intention to use either features. I did try the dynamic EQ but I did not like it at all. I have to admit though, the first time I listened to the AV7005 I thought it was true that Marantz had a “warm” signature sound but quickly found out it was because Audyssey had Dynamic EQ default to “ON”. I turned it off, and that warm tube like sound disappeared.

Setup

It seems that Marantz implemented MultiEQ XT very well as it sailed through the process in much shorter time than my Denon 4308 did. The EQ graphs are also much easier on the eyes than the 4308's.

Setting up the I/O’s are easy, I see no need to read the manual at all. It does not have wifi, so that makes setting up the network stuff is also simpler. In fact there is nothing to do as everything just works right out of the box. In fact, the reminder for the available Airplay upgrade pops up in no time, what a nuisance! I finally got tired of it so I turned off the upgrade notice this morning.

AV performance

The Marantz sounds excellent with both movies and music but I cannot use expressions such as “day and night”, “a veil has been lifted” kind of comments to describe any sound quality improvements. I can certainly say that this system does not sound thin, bright, or warm. To me, listening to CD or BR concerts, it just sound good and neutral, relative to the way I think live music should sound in concert halls. Of course I am going by memory, and it is just my subjective feeling. In my case, it tends to support, to a point, the “all amp sound the same in a controlled comparison” claim but this is separate topic. I mention this not to provoke another debate but just to make a point that if you are looking for a different sound or a Marantz signature sound you may want to look elsewhere or go for the higher end Marantz models. What I am willing to say is that I am very happy with its audio performance. So much so that I have been listening to my SACD (2 channel only for now), DVDA and some of my favourite high end CDs almost non-stop, without getting tired.

For 2 channel listening I do prefer the 4308’s features. The Denon allows me to select the subwoofer on or off. With the AV7005 if I want the sub off, I must select pure direct. The Denon also allows me to have the loudspeakers set to large for 2 channel listening without the sub. With the AV7005 I assume it would have the speaker configuration disabled but the manual does not say anything about it.

For movies, I have read about people claiming that the AV7005 offers more sound from the surround channels. May be I am affected by what I read, it does seem to offer more sound from the surround channels. I don’t know whether the AV7005 exaggerates the surround channel contents or it is in fact more accurate, but for movies I don’t mind hearing more from the surround channels at all.

On the video side, there is not much to write about, other than once again the often hyped up important criteria of having the ABT VRS, Reon, Marvell or whatever on board really need to be downplayed so people don’t get the impression that their DVDs will all suddenly look great almost like BR, if only they have one of those VP on board their AVR. The fact is, being open minded, I forced myself to spend time comparing the effects of using my players built-in VP, the TV, and the Marantz’s ABT2015. To my eyes, the results are practically the same, if anything, I would rank using the Marantz to upscale yielded slightly poorer PQ but I really am not sure. Now there is one more chance, as soon as I get my hand on the Oppo 95 I will let you know whether that one makes any difference. Those who enjoy watching test patterns will for sure see the difference but I just could not see all those VP schemes making much visible difference in real world video material unless one looks very hard for such differences.

That’s all I have to report for now, I am going back to play another disc and then watch a movie or two. I am very happy with my purchase, though I will miss my Denon. Everything I stated so far are based on my preliminary impression. I reserve the right to change my story as I spend more time exploring and enjoying the unit.

 

[TLS Guy]

That explains why he had that loud hum and got it fixed but I still don't understand how his ungrounded prepro and amp with obviously many other things interconnected would not have an audible hum with volume at +18. I can almost guarantee any digital multimeter will reveal those phantom (capacitive coupling) potential differences between his many equipment chassis with the interconnects removed. So I am pretty certain his interconnects would have to carry some sort of loop currents. I specified digital meter because but you and I should both know why an analog (e.g. AVO) meter would likely not show those voltages so we don't need to go there.

I realized that such loop currents would be extremely low but at +18 volume I still would expect an audible (though could me barely audible) hum. This is simple physics/electrical theory. I have that kind of very low level hum in all my systems, now and in the past, and in other people's systems. I also have no trouble accepting such extreme low level noise because it is really far from being audible in normal listening environments. To do what you have done to your system is too much work for me for so little gain so I am not going to climb that tree.

My point is simply that how could he has a silent system, without doing what you did?. Further, his system obviously was not inherently immuned to ground loop original noise to begin with, as the cable TV thing did cause loud hum.

Now I can't wait to hear your theory, again specifically about a speculative explanation of his silent system without really managing those phantom potential differences inherent in the unground systems.

Peng, without being there I have no idea. All I know is I have never seen a system that does not produce some noise at full gain, especially being fed from high gain circuits like turntables and tape recorders.

Although I have to say mine is pretty quiet on the digital interconnects, but noise is not 100% absent. On Thursday, my fiber optic internet network is being connected, so we will see what eliminating that ground loop does.

Really all that is required is that you can't here any noise in a quiet room at the seated position, at the highest gain settings that you could feasibly use. That really is the yardstick for quiet in my view.

 

[GranteedEV]

Really all that is required is that you can't here any noise in a quiet room at the seated position, at the highest gain settings that you could feasibly use. That really is the yardstick for quiet in my view.

I'd agree, and I'd argue that non-dedicated rooms will always have a higher noise floor (things like furnace vents, fridge hum, outdoor traffic, outdoor wind, people walking around in other rooms, especially upstairs, playstation 3 or computer fan if that's what you use as a source etc) which we don't normally notice because we're so conditioned to hearing it) than the noise floor of decent electronics anyways.

 

[AcuDefTechGuy]

I don't have any kind of hum issues right now at any volume level with either unbalanced or balanced cables and analog or digital cables.

When I listen to music, everything else is turned off (PCs, Projector, TV, etc.) so it is extremely quiet in my room.

I have 2 things to say.

1) As long as the hum is inaudible, I would not worry about it. No one listens to +18 volume anyway.

2) If I can eliminate the hum completely by doing simple things like changing from analog over to HDMI cables or Denon-Link cables or Balanced cables or adding a RF ground loop isolator to the cable coax line, I would try it.

 

[PENG]

1) As long as the hum is inaudible, I would not worry about it. No one listens to +18 volume anyway.

2) If I can eliminate the hum completely by doing simple things like changing from analog over to HDMI cables or Denon-Link cables or Balanced cables or adding a RF ground loop isolator to the cable coax line, I would try it.

1) I fully agree with that, in fact I am happy with hum inaudible even at 0 with ear almost touching driver. I was just curious about how you could achieve complete quietness.

2) I would too, just being crazy, but I would not use cheater plugs and anything that may degrade sound quality.

 

[AcuDefTechGuy]

1) I fully agree with that, in fact I am happy with hum inaudible even at 0 with ear almost touching driver. I was just curious about how you could achieve complete quietness.

2) I would too, just being crazy, but I would not use cheater plugs and anything that may degrade sound quality.

The FACT is, only CRAZY people like us would even know about the existence of such "hum" to begin with!

We look for noise where there isn't any at insanely detrimental volume.

I have never listened to a volume greater than -14 dB on my Denon 5308 or AVP-A1HD.

My heart was pounding and the sweat was pouring down my face as I pointed the remote at the processors (with the finger on the OFF button) and reluctantly increased the volume to +18dB (with the universal player in STOP mode).

 

[PENG]

HTM reviewed the AV7005/MM7055 complete with lab measurements. The THD+N, cross talk and SN figures are almost the same as those for the AV8003 and I think the freq responses are actually slightly better (by memory right now but will double check). The MM7055's numbers are not as good as the MM8003's so I guess I made the right choice. Interestingly again, XLRs got worse numbers than RCAs.

 

[GranteedEV]

Everyone who's spent an hour already in 2011 with their ear pressed against a tweeter or subwoofer raise their hands

What are the pre-out voltage measurements of the 7005?

 

[PENG]

Everyone who's spent an hour already in 2011 with their ear pressed against a tweeter or subwoofer raise their hands

What are the pre-out voltage measurements of the 7005?

I dont know how many did but I spent much more than an hour, good thing my speakers have nice grilles on them. For some reasons I thought I should blame ACDTG. The review is not posted on their website yet so I should PM you the numbers or you can read the one for the AV8003 as the numbers are almost the same, +/- a dB or so. I don't remember if they measured the pre-out voltage though. If not I can measure it myself but not right now.

 

[TLS Guy]

Everyone who's spent an hour already in 2011 with their ear pressed against a tweeter or subwoofer raise their hands

What are the pre-out voltage measurements of the 7005?

The 8003 has lots of head room. I measured 14 volts at the RCA outputs at the onset of clipping.

On the line in, it took 15 volts at clipping. 400 mv in results in 1 volt at the RCA outs.

 

[TLS Guy]

Interestingly again, XLRs got worse numbers than RCAs.

That is the way it usually is. The home and the professional environments are totally different.

Peter Walker refused to put balanced in and outs on his domestic Quad gear for just this reason. The pro versions all had balanced xlr.