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Marantz CINEMA 70s AVR - Teardown, personal thoughts and a few measurements

popej

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Original bias voltage: ECO-Mode OFF 5.2mV, ECO-Mode ON 3.9mV vs. increased bias voltage: ECO-Mode OFF 8.3mV, ECO-Mode ON 4mV
Maybe power amplifier has RC bootstrap instead of current source at voltage amplification stage (like Denon x1000 series).
 

Paweł L

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I would like to see the rest of the power amp stage schematic to see what kind circuitry is implemented. As for the particular pair of Sankens used, they're very popular in other AV receivers and also known to fail, due to too small heatsink used in multi channel AVRs, rated between 70 to 100W per ch. I think they rated at 10A, 150W, which is OK for something like the small 2ch Onkyo 9100. But their SOA in AVR, with multiple channels running, will be severely reduced, so from the perspective of long, trouble free usage good ventilation is a must. Most likely it is also a reason why Marantz runs them 'kind of underbiased' to keep heat dissipation low. Definitely budget oriented design.
 

Thomas_A

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I would like to see the rest of the power amp stage schematic to see what kind circuitry is implemented. As for the particular pair of Sankens used, they're very popular in other AV receivers and also known to fail, due to too small heatsink used in multi channel AVRs, rated between 70 to 100W per ch. I think they rated at 10A, 150W, which is OK for something like the small 2ch Onkyo 9100. But their SOA in AVR, with multiple channels running, will be severely reduced, so from the perspective of long, trouble free usage good ventilation is a must. Most likely it is also a reason why Marantz runs them 'kind of underbiased' to keep heat dissipation low. Definitely budget oriented design.
I can send you the NR1710 service manual, it is basically the same power stage.
 
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MLaranjeiras

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Marantz CINEMA 70s AVR has been recently reviewed by @amirm here and I had it purchased online a couple of hours prior to the above review to be published on ASR. Also, audio.com.pl had it reviewed earlier as well.

View attachment 337062
Front side with the Inputs selector

View attachment 337063
Front side with the Volume rotary knob

I bought it for improving movies listening experience in an audio surround environment, for its PRE-OUT outputs for all its 7 channels, but also because it was the only AVR with a low height I’ve seen on the market at a reasonable price. I paid for it 646 EUR on amazon.de with free shipping, so it’s an OK price I’d say. I had it connected to a couple of Canton GLE 496 as Front speakers, one Magnat S 14C as Center, a couple of JBL Control 28-1 as Surrounds, a couple of JBL Control 23-1 as Front Height / Atmos and a SVS SB-3000 subwoofer.

View attachment 337064
Rear view with the PRE-OUT outputs

For those willing to read the Datasheet can have a look here or to the infosheet here, while the Owner’s Manual can be read here while its PDF version can be download from here.

I did like the way it was packed inside, very organised and all items were safely arranged in there, without using a lot of cardboard, but also protecting just fine the inside equipment and accessories. The corners were also perfectly protected and the cardboard was of a good quality and hard to bend. The new design of the CINEMA series is definitely better than the old one that I have known for a couple of decades. A TV attached would be needed to set everything up, as the AVR will not operate otherwise, not even as a stereo amplifier. So, all relays will remain open until the setup gets finished.

View attachment 337061
Top shot of the packaging

The startup takes about 30 seconds, probably a bit longer than I was expecting, but this is something normal for all contemporary AVRs that are filled with several chips inside and each chip has its own startup time, then they all need to sync together and work in such a way a central microprocessor tells them to.

The Setup menus are similar to other’s AVRs from the market, with lots of settings from where you can set up both Audio and Video, but also the ubiquitous Audyssey settings from where you calibrate your audio setup, but you can also manually modify the calibrated audio measurements as per your liking. An ADC chip, I wasn't able yet to identify it, is handling the analogue Mic-input for the Audyssey microphone, so the AVR to be able to calibrate its sound by reprogramming the settings inside the DSP chips to modify the audio coming from each speaker in a way to make for the listener the best audio experience for its home theatre. It basically corrects phase issues, timing between channels, volume levels, but it also has a parametric equalizer that corrects deeps and peaks to flatten the sound and to make it sound as good as a "reference" audio system

View attachment 337067
Very accurate distance measurements, except for the subwoofer where it's not 4.74 m, instead it's 3.80 m

View attachment 337068
Speakers levels after Audyssey calibration can later be modified if needed

View attachment 337069
High pass filters for each set of speakers can also be adjusted by the user

View attachment 337002
Bass LFE crossover can be adjusted later if needed

View attachment 337070
Bass can be extracted from the Front channels as well and the crossover frequency can be manually altered when needed

View attachment 337066
Audissey EQ curve from my CINEMA 70s in my living room

The Power On Level can be set to a desired value between 1 and 98 or to Mute or to Last, but it can also be set to a hard limit between 60 and 80 which might be a good thing if you don’t want someone else to increase the max. volume past this level. I set it up myself to 80 which is a reasonable high value for my living room and this way will ensure that the amplifier itself will not overheat and our hearing will not be damaged at the same time.

When I want to listen louder I connect the PRE-OUT of the Front channels to my Yamaha A-S701 external amplifier, this way the internal power supply of the CINEMA 70s will be able to deliver more current to the remaining five channels achieving lower distortions for the output stages. The volume level for the A-S701 I need to set it up to precisely 12:30 o’clock to match the exact output level of the CINEMA 70s, then I set master volume through the CINEMA 70s’s volume knob that will change the volume on all the five channels and on the two Front PRE-OUTs connected to A-S701 at the same time.

The case is not grounded and the power plug is also a 2-pin model, so the amplifier is an IEC Class 2 device, more details here. However, there is a dedicated grounding screw on the backside, but this is most likely to get all the audio sources to the same potential in case of hum noises.

View attachment 337014
Bottom part of the mains plug

An audio DSP chip made by Cirrus Logic CS49844A-CQZ is located on the main board. As per manufacturer wrote: “The DSPs support all legacy DVD audio codecs and all Blu-ray Disc® audio formats, along with enough DSP capacity to support a wide variety of concurrent post processing algorithms all in a single chip without need for external memory”, so I suppose it’s used to decode all 70s’s audio formats for music playing.


Another chip marked R5F564MJCDFC, from the RX64M family of MCU’s manufactured by Renesas, is a 120-MHz 32-bit RX MCU with on-chip FPU, a 3 Mbytes internal flash memory and 512 Kbytes RAM. It seems to be taking care of Ethernet communications and USB communications too.

View attachment 337024
The microcontroller that seems to take care of Ethernet and UCB communications

A Pango PGC1KG 6CFBG256 programmable chip is part of the Compa series of FPGA chips (see also https://www.audiosciencereview.com/forum/index.php?threads/understanding-fpgas.249/) “suitable for system configuration, interface expansion and bridging, board-level power management, power-on sequence management, and sensor fusion. and other application requirements, it is widely used in communications, consumer electronics, drones, industrial control and other fields”. It supports 1276 LUT4 operations and 1595 flip-flop numbers.

View attachment 337022
The FCPGA chips that takes care of main board operations

A Panasonic MN864788 integrated circuit is most likely handling the remote control operations, but it’s hard to find the datasheet for this chip, nor schematic examples using it. However, it appears to be widely used in Denon / Marantz receivers.

View attachment 337025
The microcontroller that seems to take care of IR remote operations

Four PCM5102A and one PCM5100A DAC chips are handling digital to analogue audio streams decoding for all the 7+2 channels.

View attachment 337028
The DAC chips that handles Digital to Analogue conversion of the audio streams
View attachment 336993
PCM510xA DAC chips specs differences

The mains AC voltage that comes from the transformer is regulated by a 25A D25XB60 bridge rectifier followed by a couple of 6800 uF / 63V @105C electrolytic capacitors.

View attachment 337044
The two 6800 @ 105C filtering electrolytic capacitors following the AC / DC bridge rectifier

There are a few 3-pin fixed linear regulators, manufactured by KIA Semiconductor Technology, following the above bridge rectifier, like 7805 for the +5V rail, 7807 for +7V and 7907 for -7V, that along with many other smaller regulators from the electronic boards are providing power to all the stages of this AV, but also to the relays and to logic components from the main board.

View attachment 337029
The AC / DC bridge rectifier and the linear regulators around


View attachment 337045
A couple of fuses that located around the bridge rectifier

The output power stage is built around seven pairs of complementary Darlington transistors: SANKEN 2SB1560 being PNP and SANKEN 2SD2390 being NPN. These are 10 A and 150 W powerful transistors used in many AV receivers, some of them having twice CINEMA 70s’s power, so at least in theory, with a beefier power supply and with active cooling this AVR could be transformed into a more powerful one, tough some say that the on-die biasing resistor might get damaged in case of overheating. Not just Denon / Marantz are using these transistors models, but also Pioneer, Onkyo, Cambridge Audio and perhaps other manufacturers too.

View attachment 337031
A pair of SANKEN 2SB1560/2SD2390 Darlington transistors from the output stage

Below there is a schematic with the amplifier inside the Onkyo A-9010 AVR that is built around the same 2SB1560/2SD2390 pair of transistor, that seems to have a similar output power as the reviewed one:

onkyo-a-9010-amp-jpg.649206

Onkyo A-9010 Audio Video Receiver ampilfier schematic

There is an Auto Power Off feature implemented in CINEMA 70s that takes care of two zones independently: Main zone consists of five internal amplifiers 5ch+Sub1, while Zone 2 consists of the remaining two internal amplifiers 2ch+Sub2 from Surround Back R+L, but it can also take care of all 7.2 channels, depending on the settings we choose from the Settings menu. This will ensure that when we're listening to 5.1 environment the remaining couple of channels could get into a stand-by mode and vice-versa, when we listen to Zone 2 stereo speakers the remaining 5 channels will get into a low power state according to the Power Off settings we set up. Basically, if the AVR is not going to be used for the no. of minutes/hours that was setup earlier then it will automatically shut off entirely or only one of the two Zones.

Another energy saving feature is also the Eco Mode that allows energy saving when set to ON. With Eco Mode set to OFF I measured an idle power consumption between 25.8-27 W, while with Eco Mode set to ON it got lowered to 18.5-19 W, so quite a low idling power consumption for an AVR. Exactly the same 18-19 W value I was getting while listening to a low power level late evening. Compared with my stereo amplifier (Yamaha A-S701) that has an idle power consumption of about 20-25 W, the CINEMA 70s with its 27 W seems resonable to me, especially the 17 W value with Eco Mode turned ON).

Eco Mode setting turned to OFF

View attachment 337035
Eco Mode setting turned to ON

For those willing to use this AVR on moderate levels for watching movies I think they might experiment with different power levels until they find the “sweat spot” that will better blend energy consumption and output power. However, below are a few Eco Mode ON vs. OFF measurements and my 2 cents thoughts as well.

With Eco Mode turned OFF I measured on Front outputs a SINAD of 75.1 dB at about 5 W / 4 Ohms and turning this feature ON lowered the SINAD to 59.7 dB, so a decrease of about 15 dB in SINAD and also in THD+N. Similar measurements done for about 21.5 W @ 4 Ohms showed that SINAD decreases from 80.7 dB to 43.5 dB, meaning a difference of 37.2 dB, so increasing the volume when Eco Mode is turned OFF may not be a good idea, unless energy consumption matters more than audio quality.

I was able to measure at 5 W / 4 Ohms (approx. 4.5-4.6 V RMS @ 4.1 Ohms) a SINAD of 75.1 dB on the Front Right channel and about 69.9 dB on the Front Left channel, a SINAD of 78.5 dB on the Surround Right channel and 77.5 dB on the Surround Left channel. It's interesting to see that the Surround channels are a bit better in terms of SINAD / THD+N than the Front ones, kind of unexpected.

Increasing the volume a bit more, to about 22 W / 4 Ohms (approx. 9.4-9.4 V RMS @ 4.1 Ohms) improves SINAD results to 80.6 dB for the Front Right channel and to -73 dB for the Left one, while the Surround gets to -80.8 dB for the Right channel.

What's very interesting is the difference between the SINAD figures when comparing ECO Mode OFF vs. ON. For the Right Front channel there's an increase from 75.1 dB to 59.7 dB @ 5W and from 80.7 dB to 43.5 dB, so much worse than the distortions at 5 W, which is quite normal given that enabling the ECO Mode feature means lowering the voltage for the output stage. To summarise, the ECO feature does a good job for low output levels up to 10W / channel, while for higher output levels it should be left OFF or to AUTO to ensure that the distortions will not become audible. Worth mentioning that a SINAD of 43.5 dB means 0.668%, but most people don't perceive distortions if below 1%.

View attachment 337047
Front channel Right, SINAD of 75.1 dB, 5W @4Ohms, Eco Mode OFF

View attachment 337046
Front channel Right, SINAD of 59.7 dB, 5W @4Ohms, Eco Mode ON

View attachment 337049
Front channel Right, SINAD of 80.7 dB, 21.5W @4Ohms, Eco Mode OFF

View attachment 337048
Front channel Right, SINAD of 43.5 dB, 21.5W @4Ohms, Eco Mode ON

View attachment 337050
Surround Right channel, SINAD of 78.5 dB, 5W @4Ohms, Eco Mode OFF

View attachment 337051
Surround Right channel, SINAD of 80.8 dB, 21.5W @4Ohms, Eco Mode OFF
I haven't noticed a better SINAD result when using Pure Direct, though the "skirt" around the fundamental signal disappears completely with Pure Direct pushed, so the output signal is cleaner when Pure Direct is pushed, although this doesn’t change the final THD+N results.

View attachment 337052
Pure Direct on Front channel Right, SINAD of 74.7 dB, 5W @4Ohms, Eco Mode OFF


How is Marantz / Denon achieving such an energy saving with this Eco Mode feature? They added a rather big and powerful relay HF115F / 012-2ZS4A 8A/250VAC on the main board that seems to switch on-the-fly from one winding of the transformer to another one, decreasing the AC voltage that powers the bridge rectifier shown a few paragraphs above. I measured 96.5 VDC on +/- rails of the bridge when Eco Mode is turned OFF and 38.53 VDC with this setting turned ON, an unexpected big difference. What’s important is that turning the Eco Mode OFF is indeed saving a lot of energy. Another example is when I was listening to a rather compressed song to a bit over 90 dB peaks and I’ve noticed that by turning the Eco Mode ON decreased energy consumption from 96 W to 47 W maintaining the same output level; audibly it was very difficult for me to notice the increase in distortions, although focusing only on the bass I think it was a slight difference.

View attachment 337042
DC voltage with Eco Mode turned OFF

View attachment 337043
DC voltage with Eco Mode turned ON

View attachment 337037
The relay for ECO Mode setting is in the bottom-right of the image\

Below I'm posting a few pics with the internals. I find the modular design and implementation to be easier to service, at least for the authorised repair services where they simply swap the defective module with a new one.

View attachment 337036
The AC transformer is on the left, the 14 powerful output transistors are on the bottom

View attachment 337038
On the mid-left, with heatsink on top, there is the MBBVOP13082E module that takes care of wireless comms.
On the right there is the small power supply that takes care of powering the device On / Off.


When listening loudly to music tracks on all 7 channels, the inside temperature of the hottest components from the upper board gets to 60 - 63 C, while the output stage’s heatsink reaches 53 - 56 C, with top case taken off; I expect with the case back on and with the AVR placed in small cabinet / rack or inside the furniture things to get much hotter inside, with at least 10 C more, especially when listening to music on all 7 speakers.


Given the passive cooling of the CINEMA 70s, I would recommend this AVR to be placed on a well ventilated place, same being recommended by the manufacturer as well, as per Owner’s Manual (PDF manual here):

“Power turns off and the protection circuit indicator flashes in orange approx. every 2 seconds.
  • The protection circuit has been activated due to a rise in temperature within this unit. Turn the power off, wait about an hour until this unit cools down sufficiently, and then turn the power on again. (v p. 276)
  • Please re-install this unit in a place having good ventilation.”

Marantz CINEMA 70s also has more protections in place that turns the device OFF in case of a short-circuit on the speaker cables or in case one of the speakers gets accidentally removed while playing, as per below:

“Power turns off and the protection circuit indicator flashes in orange approx. every 0.5 seconds.
  • Check the speaker connections. The protection circuit may have been activated because speaker cable core wires came in contact with each other or a core wire was disconnected from the connector and came in contact with the rear panel of this unit. After unplugging the power cord, take corrective action such as firmly re-twisting the core wire or taking care of the connector, and then reconnect the wire. (v p. 34)
  • Turn down the volume and turn on the power again. (v p. 70)
  • This unit’s amplifier circuit has failed. Unplug the power cord and contact our customer service center.”
Thank you for reading and I'm wishing Merry Christmas to all Christians and Happy Hollidays and a Happy New Year to all of us!
It is a little sad to realize that old issues like hi temperature still after decades from early models, while price go to stratrosphere on the newer ones
 
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trl

trl

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I would like to see the rest of the power amp stage schematic to see what kind circuitry is implemented. As for the particular pair of Sankens used, they're very popular in other AV receivers and also known to fail, due to too small heatsink used in multi channel AVRs, rated between 70 to 100W per ch. I think they rated at 10A, 150W, which is OK for something like the small 2ch Onkyo 9100. But their SOA in AVR, with multiple channels running, will be severely reduced, so from the perspective of long, trouble free usage good ventilation is a must. Most likely it is also a reason why Marantz runs them 'kind of underbiased' to keep heat dissipation low. Definitely budget oriented design.
There's a schematics on the other page, but also the one from below, both are probably very similar with the one from CINEMA 70s.

Marantz_1510_1710-schematic.png
 
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trl

trl

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It is a little sad to realize that old issues like hi temperature still after decades from early models, while price go to stratrosphere on the newer ones
Not very high temps, but still a bit higher than I'd like to see in my amplifier, at least when listening to higher levels on all 7 channels. However, I temporarily placed on top a cheap 120mm low-height 12V fan, recovered from an old computer case, powered at 5V straight from the front USB port via an USB cable. I've used some rubber feet (orange/white) to absorb the "windy" noise and any possible vibrations and now the fan it's very quiet, even late evenings with no audio played I can't hear it. Now the case is completely cool, even on very high volume levels. Unfortunately, the USB power stays ON forever, even if I place the CINEMA 70s in stand-by, but I always use Tuya/Alexa compatible power outlets, so I power On/Off my Hi-Fi devices via Alexa.

IMG_4712_.jpg

Temporarily fan placed on top of the CINEMA 70s

A fan can also be installed inside with ease and 7V can be obtain from the one of the KIA 7807 power regulators nearby, but I'll see about that when the warranty will end.
 
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capslock

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Ok, if that is the schematic, it means the bias of the LTP input pair and the VAS are largely independent of the supply voltage. The current source that feed the LTP has a voltage reference, so it does not care much about the absolute supply voltage, and the current in the VAS is determined by the current in the + half of the LTP. However, since the circuit has no current mirror, the balance of the LTP is at the mercy of component tolerances, and this balance might change considerably if the supply is reduced. A more unbalanced LTP means much higher harmonics.

Also note that the output stage is a bad as it gets, EF2 with integrated darlingtons.
 

popej

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VAS current for FL amp is: (+Vsupply -1.1)/(R4803+R4808). It is 3.8mA for 44V and would change with supply voltage. This is downside of RC bootstrap.
 

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Not very high temps, but still a bit higher than I'd like to see in my amplifier, at least when listening to higher levels on all 7 channels. However, I temporarily placed on top a cheap 120mm low-height 12V fan, recovered from an old computer case, powered at 5V straight from the front USB port via an USB cable. I've used some rubber feet (orange/white) to absorb the 'windy" noise and any possible vibrations and now the fan it's very quiet, even late evenings with no audio played I can't hear it. Now the case is completely cool, even on very high volume levels. Unfortunately, the USB power stays ON forever, even if I place the CINEMA 70s in stand-by, but I always use Tuya/Alexa compatible power outlets, so I power On/Off my Hi-Fi devices via Alexa.

View attachment 338823
Temporarily fan placed on top of the CINEMA 70s

A fan can also be installed inside with ease and 7V can be obtain from the one of the KIA 7807 power regulators nearby, but I'll see about that when the warranty will end.
have you thought about triggering the fan with one of these placed strategically inside?

 
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Alice of Old Vincennes

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Today I uploaded the ARCG file that was used when my AVM had FW Ver. 76, and ran REW again. You can see that it has improved:
In this comparison, the only difference is the FW version as both are from using the same ARCG files, though since the red one was one on 3rd December last year, it is possible that one of the subwoofer has been moved a little bit, but more than a couple inches in any direction because there really isn't much flexibility to move it in that location.

So, I still think somehow going from FW76, to 78 and now 80, ARCG is performing much better in the deep bass range. If I am right about this, it would explain why quite a few members had reported that they felt bass lacking, after their first run of ARCG.

View attachment 337230
Unfortunately, you have to guess. Anthem needs to provide real graphs after correction. When purchased MRX 520, I naively thought corrected graph was accurate. Looked beautiful. Well respected company should know better. Better up your game Anthem. Dirac is here and Audyssey is catching up. I thought my subs sucked. Now I know.
 

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Analog inputs are digitised whenever you set L/R speakers to small (activating 12 dB/octave filter in the AVR that adds to a 12 dB/octave acoustic slope of typical closed boxed speakers). Setting L/R speakers to large will bypass ADC/DAC and you get full range. And I think you can use Audyssey on the subs if you also set L/R bypass mode in Audyssey and "main+LFE" on subs. The problem will be to integrate the mains with the subs if you have such. If you have small ported speakers you might get that ideal 24 dB/octave acoustic slope to match with the sub crossover at some frequency though.
Yes, you might.
 

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There is little to no point messing with bias at the levels you were measuring.

Bias is adjusted at low levels, say 250mW- 1W, where you are looking for the crossover notch, particularly the difference between positive and negative switch/glitches in waveform. This already partially shows in your plots where the odd harmonics are affected. At high levels like you measured, the contribution from crossover notch distortion is much less of the overall output.

It’s a poor amplifier stage, no two ways about it. Dodgy Su’scon 6800uF caps for 7 channels rated at 50wpc is an absolute disgrace. That heatsink and supply is not even adequate for 2 channels! It shows the “Marantz” of today is just a shell of a name with nothing in common with quality gear of the past.

Thanks for the ‘teardown’ @trl - I’m sure plenty of people are thankful.
Do any avr manufacturers use quality caps with sufficient heatsinks and supply currently?
 

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Do any avr manufacturers use quality caps with sufficient heatsinks and supply currently?

Some of Yamahas better AVRs sold today use high grade components (including caps) and adequate heatsinking, although they all economise to the point their continuous ratings are a bit of a mirage.

You get decent amplification, quality components, usually an excellent transformer and power supply along with good ventilation with Yamaha. Not sure about the features and bells/whistles, but their gear has always been very reliable. Whether they are behind the eight ball in terms of the latest features and formats, I'm not sure.
 

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I really feel like people need to get with the idea that this AVR is a pre-pro with the cheapest possible amplification thrown in to it. Why else would Marantz provide full pre-outs? It even has relays to depower the whole amp section when it’s not in use.
 

popej

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I really feel like people need to get with the idea that this AVR is a pre-pro with the cheapest possible amplification thrown in to it.
For about half a century there is no real problem with amps. AVR provides cost effective solution. Some can accuse AVR of being cheap, others praise AVR for being cheap.
 

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After reading this terrible review, today I bought it anyway for $799 USD refurbed. Here is why:
  • I have several HDMI sources (SmartTV with eARC, Cable box, BlueRay, AppleTV, a PC) and I need to switch between these video sources easily
  • I don't listen very critically when I watch TV like I do when listening to good old fashioned 2-channel stereo with a scotch in hand. As long as the highs are crispy and the lows are tight and deep and not boomy, I am happy.
  • I have dozens of other amplifiers to play with from old Adcoms, to Parasounds to Crown XLS and XTi's to various Class D amps, etc. Non of which achieve the the holy grail >110db SINAD but can be used to by-pass the Marantz internal crappy amp.
  • My Mother-In-Law in her late 80s often comes to visit often and I need to keep things simple for her when I am not around
  • I don't have shelves with a lot of height in my AV furniture to accommodate the larger AVRs
  • And finally, I am not 100% convinced that SNR/SINAD is everything end-all be-all. I have a horrible measuring Cary single-ended tube pre-amp and matching 300B mono-blocks that never fail to give me goosebumps while listening to Sade on vinyl. I can't say I ever had that experience with some very well measuring modern gear. I don't get it, I don't understand it but I also can't explain why listening to music on some equipment raises the little hairs on the back of my neck while other gear does not. How do you measure that?
It should be here by the end of the week. I'll keep ya posted. Worse case scenario, I'll return it and try the mini-DSP route. Or perhaps you may offer a better suggestion for a processor that measures well and under $1,500?
 

Paweł L

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From the schematic of the output section I was expecting just a little bit more, something like the Onkyo 9100, but Marantz simply cut corners as much as possible. Ah, where is the Marantz of the past.
 
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After reading this terrible review, today I bought it anyway for $799 USD refurbed. Here is why:
[...]
It should be here by the end of the week. I'll keep ya posted. Worse case scenario, I'll return it and try the mini-DSP route. Or perhaps you may offer a better suggestion for a processor that measures well and under $1,500?
Well, is not that terrible, after all it has a THD+N at around 0.01% in 4 Ohms with about 20 W/channel. Congrats on your purchase and hope it will fulfill your needs.

If you do have enough space to fit a bigger AVR, then there's plenty to choose from, just lookup the 5W SINAD graph from Amir's measurements on the AVR/amplifiers.

However, looking forward for your thoughts upon arrival and after the first listening tests. Do a proper Audyssey calibration (read the howto properly), you can also use the low-cost AppStore/Play MultEQ app to edit your measurements and to push them easier to the AVR. Take care of the Crossover freqs, if your Front speakers are "seen" as Full Range you may change the Crossover HPF for your Front speakers from Full Range to 40Hz if you have a decent subwoofer attached, of course.
 

Hugo77

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I've observed an interesting trend with Marantz and Denon AVRs in Europe lately—they've been consistently offering significant discounts for months now. Personally, I recently acquired a 70s for 699 Euros with shipping, and the prices seem to have dropped even further since then. It appears that D&M is quite keen on moving their current inventory.

This marks my second experience with the 70s model. Regrettably, the first one had a power supply hum during startup, prompting me to return it. The replacement, however, seems to be in good working order. Upon unpacking, I was pleasantly surprised by its quality and robust construction, especially given the reasonable price point.

Despite these positive aspects, my overall satisfaction with the product is not as high as I had hoped, and here are the reasons why:
  1. Sound Quality: The sound quality of the 70s leaves much to be desired, with an unusual noticeable difference between normal and source direct modes.
  2. HEOS App Limitations: Despite improvements, the HEOS app falls short for me, particularly in its inability to replace my Bluesound Node, as it lacks support for Deezer HiFi.
  3. Audyssey Room Correction: The Audyssey room correction version in the 70s is completely useless. I can't overstate how bad it is.
  4. HDMI Switching Issues: HDMI switching comes with its share of problems, occasionally passing only audio without video. Resolving this issue requires switching between sources multiple times or a complete power cycle of the 70s.
  5. Pre-Amp Gain: I find the pre-amp gain barely sufficient for driving my Hypex Nilai.
  6. Display Utility: While aesthetically pleasing, the display serves little practical purpose.
I'm going to return it.
 
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