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Denon AVR-X6700H with Buckeye NCx500

Mike4700h

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I know this has been beat to death...but i still have not found a definitive answer:

I want to use pre-amp out on my Denon AVR-X6700H (L/C/R) and also use the Avr's remaining internal amps for the remaining Atmos/Auro speaker array (11.1). When used in this fashion, the Denon's pre-amp output voltage (from what i have read) is 1.4-2.0 volts. Does this rule out the Buckeye NCx500-3 that has a sensitivity of 2.4-2.5 and an overall gain "below" 29dB? Also the use of XLR to RCA cables doesn't help. I have noticed that the Emotiva offerings specify a 29dB gain structure....but there DR3 offering is showing 2.4 v input sensitivity.....I am driving B&W 802's and want max headroom.....starting to think I have to buy a separate Pre-amp processor.
 
I know this has been beat to death...but i still have not found a definitive answer:

I want to use pre-amp out on my Denon AVR-X6700H (L/C/R) and also use the Avr's remaining internal amps for the remaining Atmos/Auro speaker array (11.1). When used in this fashion, the Denon's pre-amp output voltage (from what i have read) is 1.4-2.0 volts. Does this rule out the Buckeye NCx500-3 that has a sensitivity of 2.4-2.5 and an overall gain "below" 29dB? Also the use of XLR to RCA cables doesn't help. I have noticed that the Emotiva offerings specify a 29dB gain structure....but there DR3 offering is showing 2.4 v input sensitivity.....I am driving B&W 802's and want max headroom.....starting to think I have to buy a separate Pre-amp processor.
I can tell that your avr-x6700h can drive the NCx500 with no issues assuming you need no more than say, 600-800 max. Also, you should use xlr to rca interconnect cables regardless, to minimize noise.
 
You just aren't using all of the wattage that the NCx500 has to offer, that's all. It's similar to not being able to turn the volume up to max on whatever pre-amp you are using. That is my understanding anyway.
 
The Denon AVR-X6700H can output more than 2 V by cranking up the volume knob. Performance suffers a little bit (probably a little higher noise). However, measurements were done with the speaker amps turned off. Don't know if max pre-amp output level would be different when speaker amps are on. Performance will probably be lower than when amps are off. (Link to review)

index.php
 
Think these are measurement of the original 6700H with AKM DACs. Later models had lesser SINAD? Not sure which one you have and if that difference would be really audible.


I don't think you will have a problem driving the amps to very loud levels (albeit not to max), but not sure how it works with the built in amps if you push master level to high. 6700H does not have per channel pre-amp mode, rather all on none (perhaps LR only by default if designated). I always had my 6700H in pre-amp mode and did not face the same issues.
 
Yes, the 6700 has all or none for preamp/amp selection. I think I will give it a try and see how Audyssey handles trimming the speakers with the Buckey for LCR duty.
 
You just aren't using all of the wattage that the NCx500 has to offer, that's all. It's similar to not being able to turn the volume up to max on whatever pre-amp you are using. That is my understanding anyway.
Agreed, but the 6700 can easily output 3 to 3.6 v at very low distortions even in non preamp mode so for the NCx500, preamp mode or not, it really doesn't matter. Regardless, the OP should still set the front L and R to preamp mode, i.e. pre out.
 
Pre-Amp mode is all or nothing....wish I could set it by individual speakers.
 
Probably get the monoprice XLR to RCA male/male cables. Hope they have worked out the issues.
 
The Emotiva XPA-DR3 3ch looks attractive.
400/600 W, input sensitivity 2.0V, Amp Gain 29dB, has both RCA/XLR inputs. Might be a step down, however.
 
Pre-Amp mode is all or nothing....wish I could set it by individual speakers.

It is a little more complicated than that and that's why some users get confused, or mislead.

Take a look of page 295 in the manual:

1736281370392.png


then see page 246 in the manual:

So if you select 13.1 channel, it is NOT all or none any more, almost but not quite!

1736281217425.png
 
Last edited:
I know this has been beat to death...but i still have not found a definitive answer:

One main reason for that is because it is not that simple to come up with a definitive answer. For one thing, the preamp output can vary between 0 V to > 4 V for pretty much all Denon and Marantz AVRs. It is important to understand a few basic things:

1) The exact voltage measured at the output will depend on the volume setting, obviously at volume 0, the output will be basically 0 V, and at 80-82, or 0 to +2 in the relative scale, it would likely be around 2 V or higher, and may go up to 4 V or a little higher if you keep cranking it up.

2) The pre out performance in terms of "SINAD", or "THD+N, also varies with the output voltage, and therefore the volume setting as well. Take a look of the curve NTK posted on post#4:

You can clearly see that if you would accept 80 dB SINAD, that is 0.01% THD+N, then pre out voltage would be about 4.5 V maximum, and if you keep on cranking, it will drop to 55 dB, that is about 0.18% THD+N, still not widely accepted as "clipped" at that point, though technically speaking, for sure people like Amir (me too at that point) would consider that the output is clipping already.

So, you basically need to tell us what is the maximum THD+N, or minimum SINAD you would accept, before we can say what is the maximum pre out voltage you can expect.
A further complication is, depending on the design, and in this case D+M, as the pre out voltage increases, performance in terms of SINAD would vary as mentioned earlier, and it typically would drop quickly past a certain level, in this case, that level appears to be around 1.5 and then take another dive at around 2.0 V, when the internal amps are connected. However, when the internal amps are disconnected, in the so called preamp mode, the pre output would remain relatively clean, i.e. maintaining near peak performance in terms of SINAD, until the output voltage exceeds around 3 to 4 V.

In addition to the curve on post#4, you can also look at the one presented by D+M/Masimo:

In this graph, you can see that while it is true at at about 1.4 V, THD+N started to jump quickly, but you can also see that it would settle down when the output voltage reaches about 2 V at THD+N level of about 0.018% that is still low enough for transparency, and it really did not rise to 0.03% until it reaches almost 4 V.

So, the main difference between non preamp mode and preamp mode is not so much the output voltage, but the distortions plus noise level at the same voltage you pick on the graphs.

1736282440624.png


I want to use pre-amp out on my Denon AVR-X6700H (L/C/R) and also use the Avr's remaining internal amps for the remaining Atmos/Auro speaker array (11.1). When used in this fashion, the Denon's pre-amp output voltage (from what i have read) is 1.4-2.0 volts. Does this rule out the Buckeye NCx500-3 that has a sensitivity of 2.4-2.5 and an overall gain "below" 29dB? Also the use of XLR to RCA cables doesn't help. I have noticed that the Emotiva offerings specify a 29dB gain structure....but there DR3 offering is showing 2.4 v input sensitivity.....I am driving B&W 802's and want max headroom.....starting to think I have to buy a separate Pre-amp processor.

To be clear, in such a use case, you should set the X6700H to 13.1 configuration, so that you can use the amp assign setting to set the FL and FR to pre out, that is preamp mode. You don't have to do that and I doubt you can hear the difference, but since it can be done so why not.

This way, you can listen in 2 channel stereo at volume setting that will be high enough to drive those buckeye amp or Emotiva amp to their maximum without worrying about the voltage clipping.

I read the specs of the buckeyeamp NCx500, and i noticed if you use the Hypex "gain stage" he called it, the gain is 26.8 dB that's looks high to me but I am not going to argue as he's the one selling the amps (I would have thought it should be around 25.5 dB.

Still, to be on the conservative side, let's assume the gain is only 25.5 dB, you can do your own calculations and get the following output from the NCx power amp:

AVR-X6700H pre out voltage vs buckeyeamp NCx500 output Wattage based on 4 ohm load:

Gain:25.5 dB
Pre out VrmsPower amp VoutPower amp output W
1.426.37173.86
1.630.14227.08
1.833.91287.40
237.67354.81
2.241.44429.32
2.445.21510.93
2.648.97599.63
2.852.74695.43
356.51798.33
3.260.28908.32

My suggestion, stick with the NCx500 if you want cleaner output than the Emotiva's.
 
Thanks for that explanation! I did not think to select 13.1....but makes sense since there is only 11 ch of amplification. You helped alot!!!
 
Thanks for that explanation! I did not think to select 13.1....but makes sense since there is only 11 ch of amplification. You helped alot!!!
Yep, that's exactly the trick/cheat that works on those "all or none" preamp mode avrs and avrs that have no preamp mode at all, to have effectively "preamp" mode for the two main front channels.

Amir used that trick on the avr-x3600h, got the front channels measured, and yielded almost 100 dB SINAD at 2.0 V.
 
I'm also about to invest in some external amplification. I haven't decided between Hypex and Purifi, but I'm using the several years older Denon 6300. I believe Denon specs it at 1.44V output, since it only has pre-outs, not the pre-amp mode that was introduced later. As a gut check before I decide, it seems to me that the AVR will be the limiting factor in basically all audible variables (SINAD, FR, crosstalk), so the only deciding factor is how much power I want/need to the speakers. Of course, until this AVR gets replaced by something better down the road...
 
I'm also about to invest in some external amplification. I haven't decided between Hypex and Purifi, but I'm using the several years older Denon 6300. I believe Denon specs it at 1.44V output, since it only has pre-outs, not the pre-amp mode that was introduced later. As a gut check before I decide, it seems to me that the AVR will be the limiting factor in basically all audible variables (SINAD, FR, crosstalk), so the only deciding factor is how much power I want/need to the speakers. Of course, until this AVR gets replaced by something better down the road...
No such specs at all, the spec says 1.2V and 2v for digital but that's not the maximum. There's are lots of inaccurate info and hearsay on the internet. The fact is, the 6300 through 6700 can all output up to around 4 v. As I posted earlier, you just have to know the max THD+N you can accept, then you can find out what the corresponding "max"voltage is for you. Again that "max" is not lterally the max.

Preamp mode does not give you higher voltage as such but it gives you roughly the same voltages at higher THD+N because at higher voltage, the power amp would clip and the higher distortions due to clipping would somehow get feedback to the preamp, so the preout would get higher distortions. Not likely going to be an audible issue for most applications.
 
Thanks, peng. The 1.44V I quoted comes from Denon's website, but they don't qualify at what distortion level, so perhaps it's the elbow point. However, looking at Armin's graph and the ones you posted, it looks like I could get 96db SINAD at 1.7V using the NCx500 at 250 watts/4 ohm. That's full CD performance at the speaker maker's recommended program input power, so that's probably the choice I will make. Thanks for your info on the maximum voltage. I wish Denon made it a bit clearer in their materials.
 
I am going to order the NCx500/3ch and give it a try. L/R will be Pre/Amp mode XLR and C will tbe XLR-RCA...we will see how that works. This is making me crazy enough to be considering the Marantz 8805 with Buckey Amps....and be done.
 
I am going to order the NCx500/3ch and give it a try. L/R will be Pre/Amp mode XLR and C will tbe XLR-RCA...we will see how that works. This is making me crazy enough to be considering the Marantz 8805 with Buckey Amps....and be done.
You will find that there is no issue for that combination. I know that because not only in theory, also in reality I have used my AVR-X4400H that has no preamp mode, and also used an AVR-X1800H in both preamp mode and non preamp mode with my buckeyeamp Hypex and Purifi Eigentakt amp that has only 25 to 25.5 dB gain.

Just keep in mind you will have to turn the the volume up a few clicks, but to level match the channels powered by the avr amps, you should rerun Audyssey, or simply compensate the gain differences by adding 3 to 3.5 dB to the LCR channels using the level trim settings manually. After that just sit back and enjoy the music with the peace of mind that you won't hear distortions as long as the upstream devices and contents are distortions free (audibly speaking).
 
Peng,
Thanks for taking the time to give such a detailed explanation....really helps alot!
 
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