Marantz Cinema 70s AVR Review

[EWL5]

STEREO magazine measurements for C50:
@4ohms, stereo, 1% THD: 32W per channel
@4ohms, multi-ch, 1% THD: 32W per channel
@4ohms, Impulse power, 1kHz: 42W

Why would stereo and mch give the same power?!!!

 

[peng]

You can use the Denon 3800 (which Amir bench tested) as a proxy for C50:
114 W into 8 ohms 2CH driven (95 dB THD+N)
168 W into 4 ohms 2CH driven (87 dB THD+N)

Denon AVR-X3800H Review

This is a review and detailed measurements of the Denon AVR-X3800H 9.4 Home Theater Audio/Video Receiver. It was kindly drop shipped to me by a member and costs US $1,699. Not much to say about the look of the unit as it is pretty much similar/same as last generations. Here is the back panel...

www.audiosciencereview.com

He seemed to trust his stereo magazine measurements than Amir’s. I trust Amir’s because we know the test conditions. Those low numbers he posted are not supported by the test conditions; and I wouldn’t want to guess and waste my time lol..

 

[pogo]

Why would stereo and mch give the same power?!!!

STEREO will have made the correct setting of 4 ohms on the AVR.

 

[Sal1950]

Why would stereo and mch give the same power?!!!

One channel driven measurement !

 

[peng]

STEREO will have made the correct setting of 4 ohms on the AVR.

I think so too. In that case the rail voltage for that setting is too low. So the numbers are of no practical value, other than being misleading at best.

 

[pogo]

In that case the rail voltage for that setting is too low.

No, it is not too low.
This is specified by the hardware design and set by engineering to prevent (pre-)damages.
Even amirm would no longer operate 4 ohm speakers in the 8 ohm position with the maximum possible power, as he is aware of this as well: Link

 

[peng]

No, it is not too low.
This is specified by the hardware design and set by engineering to prevent (pre-)damages.
Even amirm would no longer operate 4 ohm speakers in the 8 ohm position with the maximum possible power, as he is aware of this as well: Link

Yes, it is too low because for the same current, 4 ohm vs 8 ohms means half the watts so the output should be 55 W, and actually more at 1% THD. I am sure D+M has their reasons to design it for a lower value, but as a user, don’t be alarmed by Stereo magazine’s numbers.

By the way, Gene (Audioholics.com) like me, is also an experienced EE, he has not been shy in suggesting people to not bother using the 4 ohm setting, for good reasons. I would not go that far as to tell others what to do, because I am not covered by liability insurance lol. For my own use, I would leave mine at the default setting, for good reasons that I won’t get into here, as it would take time to explain the details, and such a discussion really belong to a separate thread. If you don’t agree, it would be because you may not have a good understanding of the related EE principles/theories, so let’s leave it at that. If you are interested, look up Gene’s article for a basic understanding of his rationale.

The article you link is irrelevant, don’t conflate liability, cya related issues versus practical issues. Amir is also an EE, I am confident he understands my points.

 

[pogo]

You haven't understood Gene correctly. He wouldn't recommend the internal AVR power amplifiers for the KEFs either, as the impedance curve and sensitivity are demanding.
Fortunately, these discussions will soon come to an end, as D&M will probably be using class-D stages for AVRs.
Experience is gained with the Home Amp and Model M1.

 

[Sal1950]

Fortunately, these discussions will soon come to an end, as D&M will probably be using class-D stages for AVRs.

I imagine your right there, in time.
But I do believe some will keep A/B around a bit for the ole timers who still haven't warmed to D amps.
I could be wrong, time will tell.

 

[peng]

You haven't understood Gene correctly. He wouldn't recommend the internal AVR power amplifiers for the KEFs either, as the impedance curve and sensitivity are demanding.
Fortunately, these discussions will soon come to an end, as D&M will probably be using class-D stages for AVRs.
Experience is gained with the Home Amp and Model M1.

Omg, that's a different topic! I was talking about Gene's view on the use of 8,4 ohm impedance setting. May be you have been reading posts with translators?

 

[pogo]

That is part of the whole truth and Gene also mentioned it in his impedance setting video 4 years ago.

 

[peng]

That is part of the whole truth and Gene also mentioned it in his impedance setting video 4 years ago.

Note: This long post is mainly for others interested in the related topic, so feel free to skip/ignore it.

You seem to be going in circle, around multiple related topics. In order not to mislead others who just happen to read you multiple points on multiple posts, I would like to summarize what I stated in my original response on yours about the Meta LS50, and the C50:

First, to @EWL5
In Post#356:

I would ignore such blanket statements, of course the C50 can do it, even easily, but as always it depends on factors such as speaker sensitivity, required spl, distance etc. Without stating the load/use conditions, any such comments about AVR can or cannot drive 4 ohm (or lower so called EPDR values) means very little.

One of my own use case described below is an example of blanket statements that are of little value:

I have driven my LS50 with my NAD amp that is rated 50 W 4 ohms that is rated 50 W, and my Denon AVR-3805 that is rated 120 W 20-20kHz 0.05% THD. So to you, the NAD amp would be suitable but the C50, that is rated 110 W, 20-20 kHz 0.08% THD is not, right, just because it does not provide a 4 ohm rating (based on your posts)

So, I agreed with EWL5 by saying that depending on factors (obviously just examples I cited, but not limited to..), the C50 can be used. Now, I can add an example of an applications:

Say someone who sits 3 meters from the LS50, and listen to a maximum 93 dB SPL (assume no room gain at all), with just one speaker, will need 55 W, based on 4 ohms, anyone who has very basic understanding of Ohm's law and power formula would know that either the 50 W 4 ohm rated NAD amp and the Cinema 50 110 W 8 ohm rated can do the job adequately, unless one listens to pure sinewave tones all day long lol..

I am making this factual statement, firmly based on science!

Another example of my own use case: My non Meta LS50, that has impedance/phase angle characteristics quite similar to the Meta version's, just a touch less demanding I would say, for my desktop application, and my tiny 40 W Fosi V3 has been doing a great job, I even had the small subwoofer remove as it became unnecessary, when I started using Dirac Live on that system. KEF recommends amplifiers rated only 40-100 W after all !!

My suggestion to you, next time when someone ask about whether he/she can use the Cinema 50 to drive his/her speakers, instead of responding with a blanket statement that AVR such as the Cinema 50 are not suitable, please ask he/she for more information about speaker sensitivity, impedance characteristics, yes include your favorite EPDR info, but include the whole curve, not a few discrete point values, seating distance, desired SPL etc., so you wouldn't unintentionally mislead anyone.

My key point is that the 110 W 8 ohm rated Marantz AVR may actually (obviously not always) do a better job with the likes of KEF LS50 and R series speakers, than some 75 W 8 ohm, 40 W 4 ohm rated integrated class AB or class D amp. One has to considered more detailed information on the products because jumping to conclusions.

As you know, I did use a numerical example, to explain to you why the Cinema 50, rated 110 W 8 ohms, under the same conditions, except into 4 ohms, can do 55 W into 4 ohms and can Marantz could have rated it 55 W into 4 ohms, that they did by provided a 4 ohms setting, I did assume you are familiar with at least Ohm's law and the power formula:

In my post#358:

The C50 has a rating for 8 ohms, that is 110 W, that means for 4 ohms, it can do 55 W, or 27.5 W for 2 ohms using the same test protocol for 8 ohms, and should be able to do a lot more for shorter duration.

As to heat dissipation due to large phase angles, yes that needs to be considered, but the LS50 only has such relatively large angles and impedance dips at certain narrow frequency range. You have to examine the curve, don't just focus on a single point.

I hope others interested in the Cinema 50, can understand my points about why it can be used for their 4 ohm speaker as long as they consider the factors I mentioned. Also, it is very important to understand that if their use case/applications are for say KEF ref series speakers, >4 meters distance, listen often to near reference level (105 dB peak) then even some of your favorite NAD 4 ohm rated class D amps will not be suitable for their applications.

I am summarizing, and it gets lengthy out of necessity, because I am concerned someone may be misled by your blanket statements and simply included a link here and there, that are not too related, and the linked article sometimes are technical enough that many may not fully understand the implications. Really just trying to help, surely you are too.

Finally, below are a link to Gene's point on those sort of impedance switch often provided by AVR manufacturers in recent years:

Setting the A/V Receiver Impedance Selector Switch

This article explores the purpose and function of the impedance switch found on some A/V receivers. Tradeoffs of following manufacturers recommended settings are also discussed. YouTube video inside.

www.audioholics.com

You quote Amir, but incorrectly, as below is an example of what he actually suggested once:

JBL SDR-35 AVR Review

Those switches are terrible. When you set them to "4 ohm," you are actually telling the unit to severely limit power! They do that to pass UL testing for heat generation. Such switches should always be set to 8 ohm.

www.audiosciencereview.com

Those switches are terrible. When you set them to "4 ohm," you are actually telling the unit to severely limit power! They do that to pass UL testing for heat generation. Such switches should always be set to 8 ohm.

As I mentioned, I am just an EE practiced in engineering for many years, but don't have reliability insurance, so I cannot go as far as Amir and Gene might have, in recommending the "proper" used of those impedance switches/settings, but I concur with their points on the effects of those things. We only get into this discussion because you said Stereo magazines would have used the 4 ohm setting for those test, and then when I simply commented that if so, the rail voltage for that setting was too low, and you said it was not, I stated my reasoning and you did not, so let's just agree to disagree on this, I am only mentioning this for completeness of this summary of the numerous posts accumulate so far, not trying to argue with you at all.

As to the meta LS50 speakers amp requirements, looking at the actual impedance/phase angle curves are obviously much more beneficial, than simply citing a single or several discrete EPDR values:

KEF still specified their nominal impedance 8 ohms, so that's another example of why it is not a good idea to use discrete point values.
KEF also recommended "Amplifier requirements: 40–100W"

Again, this summary on many points on the related topic is to avoid anyone being mislead, if anyone (with due respect, not aim at you as I have no intention to convince you on the topic) has questions on my points, please do let me know and I will try to answer or make corrections if necessary, thank you for the patience of those who read this long summary post.

 

[pogo]

Say someone who sits 3 meters from the LS50, and listen to a maximum 93 dB SPL (assume no room gain at all), with just one speaker, will need 55 W, based on 4 ohms

However, this does not take into account that RC/tone controls can be active. AVRs are normally used in this way!
In addition, Marantz engineering has set the rail voltage at 4ohms so low for this model (limiting to 32/42W per channel) for a number of reasons (MTBF, ...).

 

[peng]

However, this does not take into account that RC/tone controls can be active. AVRs are normally used in this way!
In addition, Marantz engineering has set the rail voltage at 4ohms so low for this model (limiting to 32/42W per channel) for a number of reasons (MTBF, ...).

True, fair comments..

 

[Chagall]

Ok, my takeaway is we should act as if the impedance switch doesn't exist. Most people don't know their speaker's minimum impedance anyway.

If the amp ever goes into protection as a result of cranking it too much, it's time to think about adding dedicated amps.

However, there is big chance one pair of modern speakers in a surround setup will dip below 4 ohms if not all. Therefore, if the switch is mandatory in all cases, Marantz engineers should enable limited 4 ohms specs by default. Not promote a rare best case scenario, with a impedance switch disclaimer in the manual to cover their behinds.

Please, correct me if I'm wrong.

 

[peng]

Ok, my takeaway is we should act as if the impedance switch doesn't exist. Most people don't know their speaker's minimum impedance anyway.

If the amp ever goes into protection as a result of cranking it too much, it's time to think about adding dedicated amps.

However, there is big chance one pair of modern speakers in a surround setup will dip below 4 ohms if not all. Therefore, if the switch is mandatory in all cases, Marantz engineers should enable limited 4 ohms specs by default. Not promote a rare best case scenario, with a impedance switch disclaimer in the manual to cover their behinds.

Please, correct me if I'm wrong.

I bet their engineers know what's more right than wrong, but the marketing group typically would have the upper hand.

As I stated earlier, if they published the output specs for 8 ohms, such as 100 W, then their 4 ohms output should be half of that, i.e. 50 W. All engineers know that, but if they tried, they may be overruled!

On bench tests though, ypu can expect such 100 W 8 ohm, 50 W 4 ohm rated AVRs will output much more, likely around 130 to 150 W or even higher into 4 ohms, bevause all amps can deliver much higher current on short term basis such as in those power sweep tests, but none can output higher voltage.

The 4 ohm setting, according to Gene, is a way for them to get 4 ohm certification, I am not sure he's right, as I am not sure there is such certification.

Anyway, you can read Gene's on this yourself:

Onkyo TX-RZ70 11.2CH AV Receiver Bench Test Results!

The Onkyo TX-RZ70 11.2CH AV receiver boasts 140 watts/ch, 8K HDMI inputs, Auro 3D, FREE Dirac Live and the BEST bench test results we’ve seen in its price class. Is this the best AVR at under $3k?

www.audioholics.com

He noted the following in the Editorial:

Editorial Note: Impedance Selector Switch – No matter how tempted you may be to do so, we DO NOT recommend changing the default "6 ohm min" impedance setting of ANY AV receiver, especially this unit. All this does is starve your speakers of power, simply so the manufacturer can get 4-ohm certification (at a reduced power level) without making the receiver get too hot during their power tests. We have tested this 'feature' on virtually every receiver that has offered it in the past, and the results were always the same: the low impedance setting significantly robs your speakers of power.

At least Onkyo did not set the rail voltage too low for the 4 ohm setting, as 59 V = 42% of the 8 ohm rating of 140 W, that is closer to the theoretical 50% or 70 W. Marantz C50, if Pogo's Stereo review's 32 W is accurate, it would be just 29% of the C50's 110 W 8 ohm rating, that's why I said it was too low, however, it really makes no significant difference as we all know, in dB it makes little difference either way, 2X = 2 dB, 1/2 = only -3 dB. (Come to think of it, those stereo review numbers would make more sense for the Cinema 70, not the 50.)

 

[Chagall]

I bet their engineers know what's more right than wrong, but the marketing group typically would have the upper hand.

As I stated earlier, if they published the output specs for 8 ohms, such as 100 W, then their 4 ohms output should be half of that, i.e. 50 W. All engineers know that, but if they tried, they may be overruled!

Of course, it would surprise me if the product marketing team had the last say on what goes in the manual and did some cherry-picking with the specs. To be fair, it's their job and every company does the same. Except for maybe RME, those manuals are all engineer.

 

[peng]

Of course, it would surprise me if the product marketing team had the last say on what goes in the manual and did some cherry-picking with the specs. To be fair, it's their job and every company does the same. Except for maybe RME, those manuals are all engineer.

Right, even many "separates", such as integrated, power amps by those mainstream manufacturers including Anthem (except for their top models), NAD, Arcam, do the same so it is not just avrs, but the likes of Parasound, Bryston, Benchmark, Krell, McIntosh, Passlab etc., tend to tell more in their specs.

So, I agree they have to go with the flow in order to compete.

 

[Sky_Law]

So I bought one of these for $560 brand new to use with a pair of r3 metas and a sub. Aim is for mixed movies and music. I’m gonna buy a buckeye amp (not sure if I’ll grab an nc503 or ncx500 yet) to power the speakers.

Is this receiver worth it at this price point? I need a slim receiver to fit in my media center. Would rather buy this than spend more money in a larger media console

 

[peng]

So I bought one of these for $560 brand new to use with a pair of r3 metas and a sub. Aim is for mixed movies and music. I’m gonna buy a buckeye amp (not sure if I’ll grab an nc503 or ncx500 yet) to power the speakers.

Is this receiver worth it at this price point? I need a slim receiver to fit in my media center. Would rather buy this than spend more money in a larger media console

$560 for a new C70s is a very good price. Where did you buy it from?