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Use Onkyo TX-NR906 as a power amp: Good or bad idea?

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Robert-Hifi

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Smart choice, I'm curious to hear what you think. I wish I could get a Denon 4800H for $1,650 with a 5 year warranty.

Are you still going to use the 906 as an amp or try it with and without?
Yes, the plan is to try both. But I don't think I have enough decent RCA cables laying around right now for all 5 channels.
 
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Robert-Hifi

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If I can't get Dirac Live to work magic on the RZ50, I'll be returning it. Over 15-20 years, I have realized that the most important thing in an AVR is how it handles music because music is actually everything in movies, games, shows, and stereo. Dialogue clarity for the center is #2 and almost as important as music but subtitles can remedy it whereas nothing can make a score sound musical and grab you. Then come room acoustics, tonal accuracy, 3-dimensionality, dynamics, bass etc. Many people place bass at the top which is hilarious.

I'm thinking of the following options:

Cinema 70 $1,200 with the 8002 as an amp handling 5+2 channels (bi-amp) - cheapest solution - I'd be stuck with Audyssey MultEq which is what I have now but also keep all kinds of old connections (of course, I would need to connect the speakers to the 8002)
Sony STR-AZ5000ES For $2,100, I get Sony's Trinnov-like spatial audio and decent stereo
Cinema 40 For $3,500 and no toroidal, it had better match my old 8002 in music

I may have seen a Denon 3800h for $1,000. Maybe I should add that to the list of options with the 8002 powering all speakers. That would buy me Audyssey XT which is so close to the best Audyssey version XT32 that REW measurements are practically identical.

However, the more I think about this, the small Cinema 70 as a pre/pro is almost the easiest solution and I can stack it vertically in my BDI cabinet making life so much easier.

Did you also try Pure Audio mode or AccuEQ to see if it's just the sound character of the Onkyo or Dirac?
I don't see much benefit going for the Cinema 40. If the Cinema 70s has enough channels for your needs it's a cheap way to go the pre/pro route and keep the Marantz sound.
Even the Cinema 70s has that nice looking remote and binding posts.
Those binding posts look way better than the ones on the TX-RZ50 or the AVC-X4800H.
 

peng

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Yes, the plan is to try both. But I don't think I have enough decent RCA cables laying around right now for all 5 channels.

The 905 and 906 have very strong power amps, though 2X the power output will only give you 3 dB more spl.

The real bottleneck is the extra volume control. The Denon AVR's volume control IC, that is the NJU72343, has better specs that the one used in the 906's.

So, sound quality gain will not be there unless you actually need that 1.5 to 3 dB more power for your 4 ohm speakers.
 
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Robert-Hifi

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The 905 and 906 have very strong power amps, though 2X the power output will only give you 3 dB more spl.

The real bottleneck is the extra volume control. The Denon AVR's volume control IC, that is the NJU72343, has better specs that the one used in the 906's.

So, sound quality gain will not be there unless you actually need that 1.5 to 3 dB more power for your 4 ohm speakerd.
I don't need the 3dB extra, my room is just 4.75x3.75mtr (length x wide).
And my current front speakers are 92dB, so not a really difficult load to drive.
For me, using my old Onkyo as a power amp was more about me hoping to gain a more authoritive sound, but you think it will not be worth it?

What would the better volume control IC on the Denon mean with the Onkyo as a power amp?
Using the Denon as the primary volume control and set the Onkyo at a certain volume and don't touch it again?

It looks like I ordered the Denon just in time, because today I couldn't get the HDMI output to work on the Onkyo.
Turning it on and off multiple times didn't result in the Onkyo startup screen as it normally would.
As far as I can tell the HDMI board has gone to electronic heaven.
 

techsamurai

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What would the better volume control IC on the Denon mean with the Onkyo as a power amp?
Using the Denon as the primary volume control and set the Onkyo at a certain volume and don't touch it again?

I'm returning the RZ50 - I can't get the DIRAC measurements to work for the life of me. It's either a bug in the software, or something specific to my Dell XPS laptop, UMIK-1 mic, or my room. Either way, I can't figure it out.

I'm getting a Cinema 70 and doing the same thing you're doing. I wish I could get it in silver in the States but we're 2nd class citizens despite paying 25-40% more for all models. It's small enough that I can fit both of them in the shelves in my cabinet vertically.

I'm also curious about the volume control that Peng mentioned. I was going to set the volume of the Marantz at 70-80% and leave it there.
 

techsamurai

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The 905 and 906 have very strong power amps, though 2X the power output will only give you 3 dB more spl.

The real bottleneck is the extra volume control. The Denon AVR's volume control IC, that is the NJU72343, has better specs that the one used in the 906's.

So, sound quality gain will not be there unless you actually need that 1.5 to 3 dB more power for your 4 ohm speakerd.

Curious about that volume control, cause I'm about to do the same with a Cinema 70. I'm sending all speakers over to the old AVR. I thought I'd leave the volume at 80% on the marantz and set it to pure direct.
 

peng

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I don't need the 3dB extra, my room is just 4.75x3.75mtr (length x wide).
And my current front speakers are 92dB, so not a really difficult load to drive.
For me, using my old Onkyo as a power amp was more about me hoping to gain a more authoritive sound, but you think it will not be worth it?

What would the better volume control IC on the Denon mean with the Onkyo as a power amp?
Using the Denon as the primary volume control and set the Onkyo at a certain volume and don't touch it again?

It looks like I ordered the Denon just in time, because today I couldn't get the HDMI output to work on the Onkyo.
Turning it on and off multiple times didn't result in the Onkyo startup screen as it normally would.
As far as I can tell the HDMI board has gone to electronic heaven.
If you don't need the extra power then you will be better off not using the Onkyo as power amp, or just use it as power amp for the surround channel thereby taking some load off the Denon avr.

The volume control IC functions as a preamp, and by putting the Denon's preamp in series with the Onkyo preamp you are adding distortions and noise, even if you keep Onkyo volume fixed. Again, the issue is not just about control, but added noise and distortions. That's why many older preamps have the HT bypass feature, that allows you to avoid having the signal go through two volume control.
 

techsamurai

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If you don't need the extra power then you will be better off not using the Onkyo as power amp, or just use it as power amp for the surround channel thereby taking some load off the Denon avr.

The volume control IC functions as a preamp, and by putting the Denon's preamp in series with the Onkyo preamp you are adding distortions and noise, even if you keep Onkyo volume fixed. Again, the issue is not just about control, but added noise and distortions. That's why many older preamps have the HT bypass feature, that allows you to avoid having the signal go through two volume control.

If you put the AVR in pure direct mode, would it still add noise and distortion?
 

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If you put the AVR in pure direct mode, would it still add noise and distortion?
If using the multich inputs on the Onkyo (or other avrs that have such) you're already in a mode bypassing processing, i.e. direct/pure direct.....
 

peng

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If you put the AVR in pure direct mode, would it still add noise and distortion?
Yes, all amplifiers have distortions and noise of its own. The better ones just have less of those things.
It is probably best to look at the datasheets:

D+M/Masimo don't hide the fact that they are using the MSI chip, the NJU72343, the datasheet link has been posted many times but below are the relevant specs if you don't want to read the whole thing:

1696337473821.png
1696337535552.png


You can see why the D+M units can output > 4 V. Robert's Onkyo 906 uses the Renassas chip that is a LSI, large scale integrated, that does a lot more than just volume control. According to Dr. Rich who wrote articles on AVR build quality (A 5 parts series if I remember right) for Hometheaterhifi.com, such LSI chip probably have 2X the THD+N versus D+M's chip that is medium scale integrated, specialized in volume control.

 
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Robert-Hifi

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Yes, all amplifiers have distortions and noise of its own. The better ones just have less of those things.
It is probably best to look at the datasheets:

D+M/Masimo don't hide the fact that they are using the MSI chip, the NJU72343, the datasheet link has been posted many times but below are the relevant specs if you don't want to read the whole thing:

View attachment 316338View attachment 316339

You can see why the D+M units can output > 4 V. Robert's Onkyo 906 uses the Renassas chip that is a LSI, large scale integrated, that does a lot more than just volume control. According to Dr. Rich who wrote articles on AVR build quality (A 5 parts series if I remember right) for Hometheaterhifi.com, such LSI chip probably have 2X the THD+N versus D+M's chip that is medium scale integrated, specialized in volume control.

Thank you for the explanation, now I understand what the cons are of using a receiver with multichannel input as a power amp.
I only saw the two volume controls as two captains on a ship, which isn't ideal.
But not knowing about the added noise and distortion in that scenario.

Nice to have learned something new and it's now stored in my memory banks ;-)
I will definitely read up on the articles from Dr. Rich about AVR build quality.
 

techsamurai

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Yes, all amplifiers have distortions and noise of its own. The better ones just have less of those things.
It is probably best to look at the datasheets:

D+M/Masimo don't hide the fact that they are using the MSI chip, the NJU72343, the datasheet link has been posted many times but below are the relevant specs if you don't want to read the whole thing:

View attachment 316338View attachment 316339

You can see why the D+M units can output > 4 V. Robert's Onkyo 906 uses the Renassas chip that is a LSI, large scale integrated, that does a lot more than just volume control. According to Dr. Rich who wrote articles on AVR build quality (A 5 parts series if I remember right) for Hometheaterhifi.com, such LSI chip probably have 2X the THD+N versus D+M's chip that is medium scale integrated, specialized in volume control.


Effing Dr. Rich just had to go and spoil it for all of us... I just hope he didn't get rich from doing that :)

Does that suggest that I'm slightly better off using the SR8002?

Doesn't an external amp have distortion of its own or is that all introduced by the volume control?
 

peng

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Effing Dr. Rich just had to go and spoil it for all of us... I just hope he didn't get rich from doing that :)
You are not alone, he spoiled it for me too, right after I paid a fortune for the Marantz AV8801 flagship preprocessor at the time. He used that one as example, to show that even such an AVP (so called separate) were limited to the same (almost) performance of a $300 Yamaha AVR because of the same kind of volume IC used, he did say with better power supply and layout, it might be a little better, something like that. I didn't like to read that part, but it made sense, that would be the case, as like anything that has a chain of parts in series, the overall performance is determined by the weakest part.

Regardless, I learnt a lot from reading that 5 parts AVR build quality article, though he did make some (just a few) assumptions, such as assuming integrated amps used better volume control, not realizing there were exceptions, such even the non entry level A-S801 uses that same AVR chip (a LSI type) that he seemingly despites. Overall, a must read for AVR shoppers.
Does that suggest that I'm slightly better off using the SR8002?

Better off than what? The SR8002 has the following for volume control:
Given that it is a 16 years old design, the specs look pretty good:


Volume control:

1696348919019.png

DAC:

CS4382A

Features Advanced Multi-bit Delta Sigma Architecture 24-bit Conversion Up to 192 kHz Sample Rates 114 dB Dynamic Range -100 dB THD+N

So the DAC chip has SINAD of 100 dB, not as good as the Denon/Marantz AK4458 prior to the factory fire, but much better than the current model's PCM5102A that has SINAD of 93 dB.

It looks like the SR8002's overall pre out SINAD will be limited by the very old volume control IC's 0.005%, that is about 86 dB at 1 V assuming the opamps are not the bottleneck, that's not bad for such an old model, but it won't be as good as the Denon 3000/4000 series or Marantz C60 through C40.

Doesn't an external amp have distortion of its own or is that all introduced by the volume control?

Of course, power amps have distortions and noise for sure, nothing to do with the volume control as they don't have volume control, though some has gain control that is not the same animal. Power amps usually have higher distortions and noise that preamps/dacs, I think Amir mentioned once or twice that you would want your preamp/have SINAD 5-10 dB better than the power amps you pair it with. I don't want to misquote him, so don't take that to the bank until you can find the source, that might have been one of his videos on measurements.
 

techsamurai

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You are not alone, he spoiled it for me too, right after I paid a fortune for the Marantz AV8801 flagship preprocessor at the time. He used that one as example, to show that even such an AVP (so called separate) were limited to the same (almost) performance of a $300 Yamaha AVR because of the same kind of volume IC used, he did say with better power supply and layout, it might be a little better, something like that. I didn't like to read that part, but it made sense, that would be the case, as like anything that has a chain of parts in series, the overall performance is determined by the weakest part.

Regardless, I learnt a lot from reading that 5 parts AVR build quality article, though he did make some (just a few) assumptions, such as assuming integrated amps used better volume control, not realizing there were exceptions, such even the non entry level A-S801 uses that same AVR chip (a LSI type) that he seemingly despites. Overall, a must read for AVR shoppers.


Better off than what? The SR8002 has the following for volume control:
Given that it is a 16 years old design, the specs look pretty good:


Volume control:

View attachment 316378
DAC:

CS4382A

Features Advanced Multi-bit Delta Sigma Architecture 24-bit Conversion Up to 192 kHz Sample Rates 114 dB Dynamic Range -100 dB THD+N

So the DAC chip has SINAD of 100 dB, not as good as the Denon/Marantz AK4458 prior to the factory fire, but much better than the current model's PCM5102A that has SINAD of 93 dB.

It looks like the SR8002's overall pre out SINAD will be limited by the very old volume control IC's 0.005%, that is about 86 dB at 1 V assuming the opamps are not the bottleneck, that's not bad for such an old model, but it won't be as good as the Denon 3000/4000 series or Marantz C60 through C40.



Of course, power amps have distortions and noise for sure, nothing to do with the volume control as they don't have volume control, though some has gain control that is not the same animal. Power amps usually have higher distortions and noise that preamps/dacs, I think Amir mentioned once or twice that you would want your preamp/have SINAD 5-10 dB better than the power amps you pair it with. I don't want to misquote him, so don't take that to the bank until you can find the source, that might have been one of his videos on measurements.

Yeah but won't it make a difference that the C60-C40 don't have a copper-plated chassis and toroidal power supply and they are running AV + sound?

If I put the C70 into pre-out, according to the review below and Marantz it'll give me a very clean pre-out signal which I can then push to the 8002's toroidal in its copper-plated chassis


Are you suggesting that my volume IC will destroy the sound of the 8002 completely? It's been very good on its own using the same IC. Adding the cinema 70 with a clean pre-out signal and the 8002 acting in Pure Direct Mode should improve sound since the 8002 is no longer handling any sound or video processing while the cinema 70 is also not handling any amplification.

Won't adding a C70 as a preamp improve my current system and yield results that are at least comparable to the Cinema 40 or better (maybe Cinema 30 grade)?
 

peng

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Yeah but won't it make a difference that the C60-C40 don't have a copper-plated chassis and toroidal power supply and they are running AV + sound?

If I put the C70 into pre-out, according to the review below and Marantz it'll give me a very clean pre-out signal which I can then push to the 8002's toroidal in its copper-plated chassis


Are you suggesting that my volume IC will destroy the sound of the 8002 completely? It's been very good on its own using the same IC. Adding the cinema 70 with a clean pre-out signal and the 8002 acting in Pure Direct Mode should improve sound since the 8002 is no longer handling any sound or video processing while the cinema 70 is also not handling any amplification.

Won't adding a C70 as a preamp improve my current system and yield results that are at least comparable to the Cinema 40 or better (maybe Cinema 30 grade)?

That volume chip can do 86 dB SINAD, likely better, so it won't destroy anything unless you have real golden ears. The C70 will not do better than the SR8002, likely worse, but the difference won't likely be audible. For 2 channel stereo music, I would use the SR8002, it has a much better power supply and power amp section.
 

techsamurai

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That volume chip can do 86 dB SINAD, likely better, so it won't destroy anything unless you have real golden ears. The C70 will not do better than the SR8002, likely worse, but the difference won't likely be audible. For 2 channel stereo music, I would use the SR8002, it has a much better power supply and power amp section.

Your point is valid though. When adding 2 AVRs together, one in pre-out, folks may not necessarily get the results they expect.

Personally, I'm not expecting it to match the AV10/AMP10 but I'm hoping to modernize my 8002 with HDMI 2.1 as well as let me get a taste of separates for a mere fraction of the price.

As you pointed out, this combination also offers the option to allow the AMP AVR to be used for stereo playback and to connect all kinds of equipment using older digital/optical/component/composite/S-Video connections.
 

techsamurai

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Quick question, is there a way to automatically power the amp AVR (8002) when turning on the pre-Amp AVR (Cinema 70)? Both the Cinema 70 and 8002 have DC Out but they don't have DC In. There's a RS232C on the 8002 but that's for servicing afaik.

I suspect the OP would also have to do that with the Onkyo 906 and Denon 4800 if he chooses to use it as an amp.

If indeed I can do it, is this the cable I'd use?


The
 

peng

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Quick question, is there a way to automatically power the amp AVR (8002) when turning on the pre-Amp AVR (Cinema 70)? Both the Cinema 70 and 8002 have DC Out but they don't have DC In. There's a RS232C on the 8002 but that's for servicing afaik.

I suspect the OP would also have to do that with the Onkyo 906 and Denon 4800 if he chooses to use it as an amp.

If indeed I can do it, is this the cable I'd use?


The
Just use one of those remote turn on/off outlets.

 
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