Matching amp(s) to speakers; speaker continuous power capability unknown

[CMcD-USC]

I don't know where your 3.29 Vrms came from.

I used the formulae that were referenced in the data sheet for the NC400 amplifier and attached as a screen shot to the post. I had no idea whether they were standardized (appears from your post that they are not since you're coming up with completely different numbers).

The question is, what is an acceptable THD+N level for you....

What should my target be in that regard? I found a user's review of the Outlaw 976 here: https://www.avnirvana.com/threads/outlaw-audio-model-976-7-2-surround-processor-review.3778/. It contains some testing results and references noise floor and THD from the test, but not sure that paints any clearer of a picture than Outlaw's own specs.

My choice would still be the AVR-X3600H, just pretend it is a preamp and save a lot of cash.

So would you say the cost of going with a preamp and separate components generally isn't justified if you're going with a good AVR and separately amplifying the front channels for stereo usage? Or is that just a generalization for the price range on which I'm currently focusing?

 

[Verdinut]

Oh no, I never heard you tell that story before! I would feel horrible if I blew somebody's speakers up like that. What were they?

That is where a power amp with a gain/volume control has some advantage. Pro audio power amps all have a gain control at the input but most audiophile/boutique power amps have none nowadays.
I used to own an amazing Sony TA-3200F 110 watt/ch stereo power amp which featured a separate volume control for each channel, and even additional power output percentage switches:

 

[PENG]

I used the formulae that were referenced in the data sheet for the NC400 amplifier and attached as a screen shot to the post. I had no idea whether they were standardized (appears from your post that they are not since you're coming up with completely different numbers).

The formula in the screenshot are correct, same as mine in my spreadsheet so the result should be the same.

square root of 300 W X 6 ohm/10^(2.58/20) (again, that's what's shown in the screenshot you attached).

sqrt(300*6)/10^(25.8/20) = 2.18 V

Can you double check your calculations?

What should my target be in that regard? I found a user's review of the Outlaw 976 here: https://www.avnirvana.com/threads/outlaw-audio-model-976-7-2-surround-processor-review.3778/. It contains some testing results and references noise floor and THD from the test, but not sure that paints any clearer of a picture than Outlaw's own specs.

I have no idea how Mathew did his measurements. It look like a bunch of graphs plotted with REW and a mic but I only took a quick glance.

So would you say the cost of going with a preamp and separate components generally isn't justified if you're going with a good AVR and separately amplifying the front channels for stereo usage? Or is that just a generalization for the price range on which I'm currently focusing?

I am not the go by ears kind of guy as from my years of experience, preamps/amps that measured well all sounded well to me. Subjective reviews are all over the place, one person will tell you amp A sounds better while another person will say no, amp B sounds much better and all tend to listen with both ears and eyes.

So yes, I trust the X3600H and X4500H will do well with your speakers, that really is the bottleneck, not the amps, assuming your listening level do not require max peak output to exceed the device limit. It is the recording quality of the media and the speakers that often determine sound quality, not whether it is one of those AVRs or an Outlaw 976, or anything else. That's just what I believe, could be wrong.

 

[CMcD-USC]

The formula in the screenshot are correct, same as mine in my spreadsheet so the result should be the same.

square root of 300 W X 6 ohm/10^(2.58/20) (again, that's what's shown in the screenshot you attached).

sqrt(300*6)/10^(25.8/20) = 2.18 V

Can you double check your calculations?

The way the equation was typeset in the data sheet, it appeared to me to be 10*(25.8/20) rather than 10^(25.8/20), so that was the source of my discrepancy.

 

[PENG]

The way the equation was typeset in the data sheet, it appeared to me to be 10*(25.8/20) rather than 10^(25.8/20), so that was the source of my discrepancy.

Yes, 10^(25.8/20) is correct, basically the formula to calculate anti log. You should be happy because the correct result is a lower voltage than what you thought it was.

 

[lovinthehd]

I communicated with the Hypex kit manufacturer yesterday and he said that shipping to the US was not a problem and that customs was taken care of through the shipper and included in the quoted shipping costs. As it turns out, they do have a reseller of their products in the US, but when I contacted them after not finding the kit on their website, they told me that they don't carry this particular kit because they believe that the build documentation included with the components was insufficient for kit builders of all levels (I looked through it and it seemed pretty straightforward to me, but maybe I'm too unskilled to know better!), so if I order a pair of kits for the front channels, I will purchase them from the source in the Netherlands.

This leads to my final question: are there any issues to be cognizant of running the front channels through totally different (brand, output, etc.) amps than I'd be running center/rear through? The NC400 kits are 400 watts/4 ohm (my front channels are 6 ohm nominal), and I'd likely run the other three through the Outlaw 2220 monoblocks or a three-channel, each of which are rated 200 watts into 8 ohms (rear channels are 6-ohm and center is 8-ohm nominal).

Yeah its easy enough to arrange a door to door shipment (DDP under Incoterms). No worries about different amps, do it all the time, just level match them as was mentioned....

 

[CMcD-USC]

Based on available published bench measurements online, the AVR-X3600H does have what most would consider clean output to 2 V and above, much cleaner than the Marantz AV7705, and even slightly cleaner than the flag ship AV8805. You may have hard time finding one though. If not, then I would grab the AVR-X4500H, no measurements on that one but I see no reason why it won't be as good.

The one thing I noticed about both of the Denon AVRs is that the pre-outs are RCA rather than XLR. Would there be any issue with using an RCA to XLR cable if using the NC400s (which only have an XLR input) to drive the front channels? The only XLR-equipped AVR I saw for $2,000 or under was the Yamaha Aventage RX-A3080 (it was $1,999... I am sure there are others but didn't spend a lot of time looking), and at that price I'm probably only a couple of hundred dollars to the good relative to the cost of using pre-amp/processor and separate amplifiers.

 

[PENG]

The one thing I noticed about both of the Denon AVRs is that the pre-outs are RCA rather than XLR. Would there be any issue with using an RCA to XLR cable if using the NC400s (which only have an XLR input) to drive the front channels? The only XLR-equipped AVR I saw for $2,000 or under was the Yamaha Aventage RX-A3080 (it was $1,999... I am sure there are others but didn't spend a lot of time looking), and at that price I'm probably only a couple of hundred dollars to the good relative to the cost of using pre-amp/processor and separate amplifiers.

If you can keep your cable lengths short, say less than 3 meters, I wouldn't bother with XLRs. That's based on my experience, though in some cases I prefer XLR just to hear that "click" (caution: some don't click, my A21 doesn't).

The XLR to RCA cables do work, just make sure you get high quality ones.

Unless you are going to use the internal amps, you would be better off going with the CX-A5100 than the RX-A3080 because as you mentioned, the price difference isn't much. My concern with the RX-A3080 is the pre out performance at >2 V, that is >4 V XLR. I don't have such concern with the Denon AVR and the Yamaha AVC.

 

[CMcD-USC]

If you can keep your cable lengths short, say less than 3 meters, I wouldn't bother with XLRs. That's based on my experience, though in some cases I prefer XLR just to hear that "click" (caution: some don't click, my A21 doesn't).

The XLR to RCA cables do work, just make sure you get high quality ones.

Unless you are going to use the internal amps, you would be better off going with the CX-A5100 than the RX-A3080 because as you mentioned, the price difference isn't much. My concern with the RX-A3080 is the pre out performance at >2 V, that is >4 V XLR. I don't have such concern with the Denon AVR and the Yamaha AVC.

Cable lengths will definitely be less than 3 meters.

I just found the Denon AVR-X4500H for a very good deal, so I think I may just go with that and get the RCA to XLR cables when I pick up the the NC400s. Thanks again for the advice.