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

Thank you very much for your response. I know there has been an upgrade to their "basic" phono preamps which now use FETs (2SK2145) between input and Opamp (see PM7000n diagram). As far as I know, this upgrade has been implemented on the PM6007 (PM6006 still without FETs, see diagram). I was curious whether this upgrade has also been implemented on the Cinema 70S. Too bad there are no longer service manuals available for download.
Thanks again and I look forward to hearing from you.

As you said, they didn't make SM available anymore so it is not possible to know the answer. Logically speaking though, it is hard to imagine they would implement that 2SK2145 thing in their lowest cost AVR, namely the Cinema 70, when they didn't even bother doing it in the PM6006 and the two channel receiver like the NR1200.

My educated guess is that the Cinema 70, like the PM6006, 6007, would not have that extra preamp stage.


Sorry, you didn't ask the following (I just found it interesting) so feel free to ignore..

Practically speaking, I wouldn't consider adding that FET stage is necessarily an upgrade anyway, Marantz seems to like to find something to precondition some audiophiles who would then have reason to think with such additions (HDAMs are the other example) would be the reason why they heard the so called Marantz sound, when all those who head such "sound" would likely not bother digging in further, by for example, doing their own AB after take precautions to remove bias, but any such talks would be moved to anther thread so I should stop lol.. In this case, at least the FET stage appear to have resulted in slightly better noise specs (probably only a few dB if based on the same input level) and tighter FR (only 0.5 dB, but...), so it imo it is a better solution than the tons of HDAMs used in their higher end integrated models.

In terms of transparency, nothing would change since they have the same Opamps and volume control ICs in the signal path anyway, so if anything, that extra stage is probably there so Marantz can claim (hence a good reason for their fans) the intended sound signature that fans with great hearing could detect it due to the altered frequency response. It is sort of hit and miss though because in such cases, personal preference of specific FR will matter, some may prefer the PM800X and higher integrated models that don't use the same technique and tend to rely on the more sophisticated HDAM implementations that are not found in their lower end products such as the AVRs, and two channel receivers.

Anyway, my guess is that if you are talking about the Cinema 70, it's phono stage will perform the same as the other Marantz, and Denon AVRs based on schematics, block diagrams from previously available SMs, obviously this is only a guess, but an educated one based on logic and circumstantial evidence.

Comparing their specs:

The PM7000N does seem to have better specs in terms of transparency, assuming it does not have additional distortions from the extra FET stage (it likely has though).

PM7000N:
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Cinema 70:
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it is hard to imagine they would implement that 2SK2145 thing in their lowest cost AVR, namely the Cinema 70
MM phono input probably existed till today, only because it is cheap. Inexpensive dual opamp should be good enough anyway. Could be different for MC cartridge.
 
MM phono input probably existed till today, only because it is cheap. Inexpensive dual opamp should be good enough anyway. Could be different for MC cartridge.
Agreed, it's sort of a Marantz thing, such as claiming the discrete hdam opamps sounds more musical then IC opammps, and ignore certain facts along the line(lie) too. They know as long as they give people a reason or 2, some people will believe it. In this case though, at least it seems credible on paper, on the noise part.
 
Thank you @trl for such an in depth review. I'm right at the end of my return window on my C70s. I bought it for the slim form factor and am horrified at the results you all have gotten. While I don't understand a large portion of the measurements I do notice that my beloved A/D/S L1290 speakers seem to have lost their soundstage while listening to two channel. There is just no magic when the chorus of Neil Young's Old Man comes in. I have a vintage Sansui AU-9500 that sounds incredible in the same room.

In regards to the poor SINAD measurements, would using an external 2 (or 3) channel amp be an improvement or are those poor measurements being taken from the front preouts?
 
Thank you @trl for such an in depth review. I'm right at the end of my return window on my C70s. I bought it for the slim form factor and am horrified at the results you all have gotten. While I don't understand a large portion of the measurements I do notice that my beloved A/D/S L1290 speakers seem to have lost their soundstage while listening to two channel. There is just no magic when the chorus of Neil Young's Old Man comes in. I have a vintage Sansui AU-9500 that sounds incredible in the same room.

In regards to the poor SINAD measurements, would using an external 2 (or 3) channel amp be an improvement or are those poor measurements being taken from the front preouts?
The SINAD at the preouts is about 90 dB: https://www.audiosciencereview.com/forum/index.php?threads/marantz-cinema-70s-avr-review.50334/
 
Thank you @trl for such an in depth review. I'm right at the end of my return window on my C70s. I bought it for the slim form factor and am horrified at the results you all have gotten. While I don't understand a large portion of the measurements I do notice that my beloved A/D/S L1290 speakers seem to have lost their soundstage while listening to two channel. There is just no magic when the chorus of Neil Young's Old Man comes in. I have a vintage Sansui AU-9500 that sounds incredible in the same room.

In regards to the poor SINAD measurements, would using an external 2 (or 3) channel amp be an improvement or are those poor measurements being taken from the front preouts?
What volume are you listening? The only difference to a separate amp I would possibly hear would be at high volume. It sounds a bit strained which might be related to clipping.
 
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