Home Theater United Episode 25 - More on amps with John Rice and John Dirk (1 Viewer)

[Brian Dobbs]

@Sam Posten You want sometime to come back down to hear dual SB3000 subs, we can work it out. I can give you the run of the theater and you can play around, demo with single and both subs. We could move then around to check out corner loading if you want. I’ve got a T-shaped room, so it might give you a sense of how your dogleg room might affect sound. I’m only HD still, so I’d want to pre-coordinate viewing material to make sure you can watch what you want. But I’ve got loads of demo scenes too.

If you’re in no rush, maybe sometime next year when I upgrade to 4K and get a new processor, there might be a time to do something crazy with a comparo between AVR and pre-pro with amps. I can’t promise, but I can imagine if I’m doing brain surgery on the system, this could possibly be accomplished.

@Brian Dobbs you’re invited too, albeit your drive time has gone up considerably, I understand

Yeah I'll have to leave early that day. ;-)

 

[JohnRice]

Not sure this was fully explained in the extemporaneous discussion:

“0 db” (zero decibel) on a receiver has no absolute meaning. And if your system has not been calibrated with your speakers, then that 0 dB volume could be anything. But it will almost certainly bear no relationship to a standard “reference level”.

If your system is calibrated to some reference level (e.g. with the internal Audyssey software or manually with a sound meter or etc), then 0 db will play at that volume on your system for content mastered to that same level.

For home theater, 0dB corresponds to the “reference level” of 75 dB*. But after calibration, trim levels can be adjusted to trivially dial that 0dB up or down so the volume knob is reading offset from whatever level you like, be it 65 dB or 85 dB or whatever you like.

But that only applies to content mastered to the same volume reference that your calibration used. If the movie / TV is calibrated for a lower level, then 0dB will play back at a lower level and you may want to dial up to 10dB to get that 65 dB source to play at your desired 75 dB nominal. Or vice versa, if the content is mastered “hot”, then you’ll want to dial it down -10 dB, otherwise your 0dB is now really an 85dB target for that particular movie.

There’s no fake, artificial, post-processing artifacts added when the volume knob is turned up past 0 db.




*THX reference level explained - Acoustic Frontiers

THX reference level explained

What is 'THX Reference Level'? Reference level is a calibrated volume setting used for both movie production (in dubbing stages and post production houses) and reproduction (in screening rooms and theaters). The human hearing system is non-linear, especially in the bass, so having a consistent...

www.acousticfrontiers.com

I completely agree, and intended to respond to explain. Different sources and different material has such a wide range of mastering levels these days, that a reliable "Reference" level is impossible to determine. As Dave has said. Also, there is no such thing as "artificial" gain. The system needs whatever gain it needs to achieve the desired playback level. The important thing is, gain (loudness) and power (wattage) are totally unrelated. That goes in the face of long-held conventional belief, which has always been incorrect.

Your preamp or receiver applies a fixed amount of gain to the signal, at all times. Then the volume control attenuates it. In essence, the gain stage over amplifies the signal, beyond anything you should ever need, then the volume reduces it to what you need. Full volume, however that is represented on the display, is zero attentuation.

 

[JohnRice]

On the recommendation for an AVR for Sam, I missed something for why the absolute top AVR was recommended. At a quick look, it seems like non-flagship models could work.

The 4700 offers VRR. Can process and output 11.2 preamp channels. So you can get 7.2.4 Atmos, and have the LCR sent to an external amp for power. That leaves the AVR power to drive fewer channels.

Caveat whatever tech specs you need that aren’t in current models. Maybe you need the flagship to get all your 8k HFR HDR VRR inputs, I don’t now. I’m a dummy on cutting edge video tech.

AVR-X4700H - 9.2 Ch. 125W 8K AV Receiver with HEOS® Built-in | Denon - US

The AVR-X4700H 9.2 Ch. 125W 8K AV Receiver with HEOS® Built-in from Denon provides high quality audio for your hi-fi needs. Explore more AV Receivers at Denon - US.

www.denon.com

Yep. Hell, I think even the 3700 processes 11 channels. Not sure about VRR. Sam was already resisting the idea of downgrading, so I didn't want to take it another step to include stepping down the receiver model. There are differences in them other than rated power output.

BTW, the 6000 series isn't actually the very top of the line. The 8000 series is.

 

[JohnRice]

@Sam Posten You want sometime to come back down to hear dual SB3000 subs, we can work it out. I can give you the run of the theater and you can play around, demo with single and both subs. We could move then around to check out corner loading if you want. I’ve got a T-shaped room, so it might give you a sense of how your dogleg room might affect sound. I’m only HD still, so I’d want to pre-coordinate viewing material to make sure you can watch what you want. But I’ve got loads of demo scenes too.

If you’re in no rush, maybe sometime next year when I upgrade to 4K and get a new processor, there might be a time to do something crazy with a comparo between AVR and pre-pro with amps. I can’t promise, but I can imagine if I’m doing brain surgery on the system, this could possibly be accomplished.

@Brian Dobbs you’re invited too, albeit your drive time has gone up considerably, I understand

Sam. I'm telling you. Knowing the types of movies you like, your sub is insufficient. Having it in the middle of a side wall isn't good either.

 

[Brian Dobbs]

Full volume, however that is represented on the display, is zero attentuation.

Is zero attenuation when I turn my volume knob up to 0 db? Still trying to understand.

 

[JohnRice]

Is zero attenuation when I turn my volume knob up to 0 db? Still trying to understand.

Zero attenuation is at whatever is the maximum volume level available on the volume control. How your preamp is configured, that's probably at +12dB. My Marantz AV7703 gives the choice to have have maximum at +12dB or 100. I use the 0-100 scale. No particular reason other than I know the concept of setting a reliable reference level, which is what the scale that goes up to +12dB is for, doesn't work properly since the mastering levels vary so much.

 

[JohnRice]

If your preamp has the option to show 0-100, you might use that instead, since it won't encourage the perception that it's adding extra gain, when it isn't.

 

[Brian Dobbs]

If your preamp has the option to show 0-100, you might use that instead, since it won't encourage the perception that it's adding extra gain, when it isn't.

Interesting. Thanks for correcting my understanding.

 

[DaveF]

Zero attenuation is at whatever is the maximum volume level available on the volume control. How your preamp is configured, that's probably at +12dB. My Marantz AV7703 gives the choice to have have maximum at +12dB or 100. I use the 0-100 scale. No particular reason other than I know the concept of setting a reliable reference level, which is what the scale that goes up to +12dB is for, doesn't work properly since the mastering levels vary so much.

I also use a 0-100 scale. Or maybe it's the absolute dB scale (0 db to 100 db). It's not the 0dB offset option. My wife hates negative numbers for volume so I gave up on that years ago.

My system turns on at 50. I dial it up to 60-65 for typical viewing. Up to 70 for quiet shows. Down to 55 for loud content. And if I'm trying to show off, I'll take it up to 75-80 on a movie demo (but then I'm regretting it for months because of tinnitus). There's a huge range of relative loudness on TV and streaming and discs. Every show and service is different and we learn that this show is quiet and that show is loud and dial it accordingly.

 

[DaveF]

Interesting. Thanks for correcting my understanding.

Get out your radio shack sound meter*. Run pink noise (per the link I gave earlier) through each speaker and adjust its trim to read 75 dB with your volume knob at 0dB.

When something is too quiet at 0dB, dial up and blame the studio for mastering it too quietly, forcing you violate your 0dB perfection to fix their errors. Likewise for dialing it down for an overly loud movie.

* since you don't use Audyssey, IIRC

 

[Brian Dobbs]

Get out your radio shack sound meter*. Run pink noise (per the link I gave earlier) through each speaker and adjust its trim to read 75 dB with your volume knob at 0dB.

When something is too quiet at 0dB, dial up and blame the studio for mastering it too quietly, forcing you violate your 0dB perfection to fix their errors. Likewise for dialing it down for an overly loud movie.

* since you don't use Audyssey, IIRC

Boom! Thanks Dave!

 

[DaveF]

You can go nuts with REW and calibrated mic, per prior show. But that's for crazy people.

 

[Brian Dobbs]

You can go nuts with REW and calibrated mic, per prior show. But that's for crazy people.

Well I might go crazy one day.

 

[JohnRice]

You can go nuts with REW and calibrated mic, per prior show. But that's for crazy people.

I find it extremely helpful. It eases those "I wonder" thoughts that tend to echo through my head. I simply don't trust automatic correction, at least not with something like REW where I can verify the results. I will dive in one day, which can last most of the day, and get things dialed in the best possible. Then after that I have no desire to revisit it, because it puts my mind at ease, so I can just enjoy the system. It's gratifying to see a problem and find a solution.

 

[DaveF]

I find it extremely helpful. It eases those "I wonder" thoughts that tend to echo through my head. I simply don't trust automatic correction, at least not with something like REW where I can verify the results. I will dive in one day, which can last most of the day, and get things dialed in the best possible. Then after that I have no desire to revisit it, because it puts my mind at ease, so I can just enjoy the system. It's gratifying to see a problem and find a solution.

I’m not saying it’s not useful. I’m saying it’s for crazy people. Of which you are one. You have to have a extra measure of passion and home-theater techno-nerdery to go into the work and complexity to make REW work. All to eke out an extra marginal amount of audio quality.

You’ve got REW. I’ve got an HTPC.

We should recognize and own our own personal crazy.

 

[Sam Posten]

Well I might go crazy one day.

We're all a bit mad here...

 

[Clinton McClure]

I still tame my sub with a Behringer Feedback Destroyer. It takes a few hours to properly set up but the results are worth the time.

 

[JohnRice]

All to eke out an extra marginal amount of audio quality.

I'll tell you what. When it comes to bass response, the results can be far from marginal.

 

[DaveF]

 

[gregw78]

Hi Sam and Bryan I have been enjoying the podcast a lot. Thanks for the efforts. I am not new to home theater but new to the forum. Not sure where to post this but you made reference to the first episode of demo material in your kaleidescape episode. In my google podcasts and pocketcasts player I could not find the episode because I think they have a limit of 5 episodeswith the same date. I found on the web and am able to play it with podbean player but anyways you could change the date on some of those first episodes so pocketcasts and google podcasts can see those episodes. Thanks!