Video chip and pure direct, what's the deal?

 

Gold Member
Username: Superjazzyjames

Post Number: 1949
Registered: Oct-10
At least a year ago, I'd made a post concerning the pure direct "feature" on my receiver (Denon DRA-397). A little background: the receiver has bass & treble controls which I don't use and a subwoofer/LFE output. It has a channel balance for the left, right and sub outs which are variable from -80 to +12 dB. Even though this is a stereo unit geared toward music, it has 3 video inputs (composite only) labelled; DVD/VDP, V. Aux and VCR. Since I am still using a CRT TV, I use this video switching feature. Putting the receiver in pure direct mode would defeat the tone controls if they were being used, sets all 3 channel balances to zero dB, turns off the loudness, shuts off the video chip and shuts off the display which I normally have off anyway. I had tried pure direct with music and was not impressed and since it kills video, making it necessay to bypass the receiver's video and run it straight to the TV to watch movies, I just figured it was just a gimmick and never used it.

Last night, I decided to watch "Terminator Salvation" in pure direct, so, I bypassed the receiver's video and watched it. I didn't hear much of a difference. Then, my son and I watched "Return of the Jedi" this way. Now THIS was an improvement! I always felt and still do, that the sound effects in the SW saga were lacking in oomph. Both Death Star explosions were always dissapointing, even in theaters. However watching it PD corrected this. Now I know that video signals use a certain amount of power. Just watch videos on your phone and see how fast the battery dies, but I didn't think it was THAT much and also, the receiver has at least a reasonably large power transformer. So if this is what I think it is, a combination of poorly recorded sound effects and the receiver's video chip taking too much power, I am shocked and amazed. This would not explain why the sound in theaters was just as lame though! Any thoughts on this?
 

Platinum Member
Username: Glasswolf

Columbia, South Carolina America

Post Number: 14815
Registered: Dec-03
Pure Direct mode is for listening to music. The purpose of this mode is to bypass all and any circuitry that would otherwise color the source signal, so you hear the CD or record exactly as it was laid down on the media you're playing. On newer receivers, it also bypasses any Audyssey type room equalization, and usually disables the subwoofer, so it's just for two-channel listening. Bypassing the video circuitry is done to avoid any interference (RF) in the signal path, they say. Part of the reason it probably doesn't typically sound good to you, is because if I understand you, you're using a two-channel system for a soundtrack that was designed for a 5.1 or 7.1 channel playback (DVD or blu-ray) and I didn't see any mention of a center channel, subwoofer, or surround speakers.

If you want a movie to sound "right," you shouold consider having a proper multi-channel system and an AVR that has room-equalization to correct for environmental deficiencies. Not having seen your actual setup, I can't really tell you precisely what the issue is, but as for theaters, it largely depends on how well the particular theater is set up, how modernized it is, what equipment they chose for the speaker system, and so forth. I've been in some really fantastic theaters, and some that were absolutely awful. When I watch the SW movies, or anything else on my own HT system, the explosions are room-shaking. It really depends on your setup, and implementation. Room acoustics play a big factor as well.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 17385
Registered: May-04
.

"Both Death Star explosions were always dissapointing, even in theaters."


Got say, the last few times I've heard Death Star explosions in real life, I was disappointed in that too. Seems like their just not making Death Stars like they used to.





.
 

Gold Member
Username: Superjazzyjames

Post Number: 1950
Registered: Oct-10
"Got say, the last few times I've heard Death Star explosions in real life, I was disappointed in that too. Seems like their just not making Death Stars like they used to."

Gotta hand it to ya Jan, that was funny!

Glasswolf, I didn't say, I didn't like the movie in pure direct. I said that the sound effects were BETTER in pure direct mode. Btw, pure direct on this receiver does NOT turn off the subwoofer. It sets the left, right and sub balance to zero dB each. In standard mode, they're adjustable from -80 dB to +12 dB. In pure direct, the loudness is turned off, if the listener uses the tone controls, they're defeated and the display is turned off. My point is that pure direct does NOT make any noticeable improvements in MUSIC sound, but DOES for MOVIES.

As for getting a multi-channel HT system, not happening. Music is my priority and movies are fine in stereo. Even though, I spend more time with music than with movies, I would only get a 5.1 to 7.2 channel system if I could afford high end. With movie sound tracks being as demanding as they are, I want to make sure each amp channel will have an ample power supply. You're much more likely to get at least a reasonably large transformer in a 2 or 2.1 channel receiver than you are in a 5.1 or more channel model and for less $. Not to mention, music generally sounds better on a 2 channel system than it does on a HT system even in stereo mode.
 

Platinum Member
Username: Glasswolf

Columbia, South Carolina America

Post Number: 14819
Registered: Dec-03
With Onkyo, the sub is defeated as well with that mode. Apparently, Denon does not do this. Anyway, I wasn't commenting on if your system sounded better or worse in PD. I was simply telling you WHY the mode disables video, and defeats all of the EQing circuitry in the receiver. The mode is *designed* for listening to music, unaltered by any circuitry.

Truth is, at most typical listening levels in the home, people don't draw enough power from any amplifier to come remotely close to clipping, or using all of the amp section's reserve power. Most people don't really have a good understanding of power to volume ratio anyway, though. That being said, if you want the best power in 2, or more channels, use a separate amplifier, not an all-in-one receiver. Multi-channel receivers actually do have a pretty substantial power supply in better quality units, anyway, since they have to be able to drive 5, 7, or even 11 channels these days. Therefore, when driving only two channels, you have that massive power supply at your disposal for only two channels, giving you a ton of reserve power. My point, however, is that if you use a multi-channel AVR and speakers for a movie, even with entry level stuff from a respected company, you're going to most likely have a better overall experience, because the soundtracks for movies are mixed for DTS, DD, and their HD versions more so than for stereo anymore, which means you get a dedicated center channel that contains most of your dialog anyway, a dedicated, discrete sub channel (for your explosions) and discrete surround for ambient sounds like gunfire, traffic, crowds, etc..

I've run a home theater with two channels before. It can never compare to a decent multi-channel system for movies and TV, which is exactly why I have two separate systems. One for 2 channel music, and one for movies. To an extent, it's really apples and oranges, due to the way the tracks are mastered and recorded for a CD, versus a blu-ray disc.

As I noted before, if your movie sounds better to you in pure direct mode, it's mostly just a matter of your room acoustics, speaker choice and positioning, and source material.
 

Gold Member
Username: Superjazzyjames

Post Number: 1953
Registered: Oct-10
"...if you want the best power in 2, or more channels, use a separate amplifier, not an all-in-one receiver."

If only I had the $.

"Multi-channel receivers actually do have a pretty substantial power supply in better quality units..."

In relation to the TOTAL rated output of all channels? Not really. My stereo unit is actualy better equiped that most HT models I've seen.

"I've run a home theater with two channels before. It can never compare to a decent multi-channel system for movies and TV, which is exactly why I have two separate systems. One for 2 channel music, and one for movies. To an extent, it's really apples and oranges, due to the way the tracks are mastered and recorded for a CD, versus a blu-ray disc."

I know, I've wached movies in 7.1 channels at friend's houses. It does not seem that you and I are quite on the same page. I am much more into music than movies. I only have one room for my system and I am not about to put both a stereo system and a HT system in the same room. So, with music being the priority, stereo it is. Why I even watch movies on this system is because I hate TV speakers and this is a huge improvement over them. I just don't see putting the money into a system that will mostly collect dust.

I have heard music on HT systems in stereo mode, even pure direct and it just isn't as good as on a 2/2.1 channel system.

My main point from the beginning has been that I heard no difference at all when using PD. However, with movie sound, "Return..." in particular, it added that missing oomph.
 

Gold Member
Username: Magfan

USA

Post Number: 2864
Registered: Oct-07
One issue with HT receivers is speaker compatibility. My Panels need not apply. Generally, 4 ohms is forbidden while some HT receivers even have a 6 ohm switch which is some PS limit switch.

The other issue with HT receivers is just how MUCH power are you getting? 100x7 when going back to the PS would require at least a 1000va transformer.
http://shop.plitron.com/shopdisplayproducts.asp?id=10&cat=Low+Noise+Power+Transf ormers+for+Solid+State+Amps
As you can see, the Piltron goes for nearly 500$, Canadian. That'll put a dent in any consumer receiver's price, for sure.
So, as a result, HT receivers not only won't drive a low impedance or high reactance load, but all channels won't meet rated power at the same time. The all channels driven test is not, I realize, entirely fair. But you are still aiming at speakers of above average sensitivity and an 'easy' 8 ohms.

'Ya got one thing 100%, though, current flat panel TV speakers are no better than a 2nd string clock radio. My old RPTV had at least minimal speakers. Designers of 'box' tvs had more space to put decent speakers.

Personally, I don't find the 2.1 system to be a deal breaker compromise, either. My room is simply not amenible to a HT install. No room for a 5.1 all-panel system! Maybe if I won the lottery?
 

Gold Member
Username: Superjazzyjames

Post Number: 1954
Registered: Oct-10
That would be one of my questions Leo. How is a 1000va power supply going to fit in the same chasis as a 100 wpc, 7 channel power amp? While GW makes a good point that not too many of us are likely to watch a movie at 100 watts each coming from all 7 channels, it's good to know that the extra reserve is there. Personally, I'd rather have 7, 5 to 10 watt monoblock amps with ample power supplies than a 100 wpc x7 receiver for watching movies or an 80 wpc stereo receiver. One thing I'll say is, give me a movie in stereo over music played on HT system any day.

Yes the speakers in box TVs were better than the ones in flat screens. They were crap too, just not as crappy. It seems that rear projection TVs were the only ones with decent spkrs, but even those I wouldn't put up against $250+ speaker.
 

Platinum Member
Username: Glasswolf

Columbia, South Carolina America

Post Number: 14820
Registered: Dec-03
actually, when driving only two speakers with a multi-channel AVR, you are putting the entire power supply behind two channels instead of 5, or 7, or 11, so you actually have more reserve, and mroe peak RMS power into one or two channels than into 5 or 7. This is why, if you look closely at AVR power ratings, most of them will state "driven into 2 channels at 20-20,000Hz) and not "all channels driven."

This talk of power really is mostly moot however, since just about any modern AV receiver can more than easily handle the loads presented at near to reference volumes. The fact is, that even at what most people consider "loud" volumes, you're not drawing nearly as much power as you probably think you are. At "loud" levels on my 2 channel system using a dedicated amplifier, and a current meter, I'm really only driving a pair of 4 ohm speakers with about 2 to 3 watts per channel of continuous power, with spikes ranging to around 5 watts at most. By the way, most modern receivers can easily handle a pair of 4 ohm speakers. My entire HT system is KEF Reference, which are all 4 ohm nominal loads. I've used these speakers for the last 10+ years, and never had an issue with any multi-channel recevier driving them to volumes that could easily be considered loud, clear across the house, which has 7350 sq ft of floor space with vaulted ceilings.. in other words a LOT of air.

Don't get so tied up with "do I have enough power?" The answer is, just about always yes, and then some. As an example of this, take a look at the Pass Labs amplifiers like the Aleph J, F5, and Zen amplifiers, rated at 18 watts per channel RMS x 2 channels, and able to compete easily with off the shelf amplifiers rated at 300 watts per channel.
 

Gold Member
Username: Magfan

USA

Post Number: 2868
Registered: Oct-07
Glass, I find myself in both modes....agree and DISagree.

The all channels driven test IS bogus. No doubt about it. Full-on? A HT receiver would be luck to put out 60% of the 2 ch rating.
However, and this is also an academic only point....you are limited in speaker choice. I'm not sure that matters for the intended market of HT folks.

Now, amplifiers are rated into a dummy, resistive load. Any mention of reactance is.....well...it's NEVER mentioned. So, you take a pair of 100x2 amps. One will drive a certain speaker without effort while the other? Falls flat on its heat sinks. Simply can't handle the load. B&W is one such speaker...some of 'em are difficult with wide impedance swings coupled with huge phase angles. OUCH!
My panels? Low sensitivity, for sure, but also no crazy phase problems. Harbeth, as Jan has pointed out, is fairly tube friendly...at least the LS3/5 version. Low sensitivity, as well, but again no wacky phase problems.
So, depending on the speaker/amp combo, you may or may Not have enough juice.
In the windows open season...you have only 2 seasons in California, windows open and windows closed, you can hear my panels a block away.
The most I've measured on my panels escapes me right now. Certainly no more than 10vac....so I'm guessing peaks to 20+ which my meter won't grab. That's about 80 watts peak into 5 ohms. I'll give it 8 or 10 watts RMS. And I know I've gotten MUCH louder. I figure a 10:1 'crest' factor for regular music.
Maybe one day I'll put on some test tones?

That's why when asked....for someone who shows signs of becoming an 'enthusiast', I try to get 'em into a pre/pro and amp. It's much more forward compatible. And, IMO will provide more long-term satisfaction.

The Pass amps? perfect for the proper speaker. For my panels? The 150.5 or its matching integrated is where the line starts. And while the XA30.5 is about 3x that when in A/B and is supposed to be a superb piece of gear, I'd go upline in the 'A' amps to at least the 100.5 monos......and the electric bill to go with'em.
The First Watt, Zen, 'F's and the rest would not get my panels off the ground for a good loud session.

For loud sessions, please keep the AVR well ventilated.
 

Gold Member
Username: Superjazzyjames

Post Number: 1956
Registered: Oct-10
Thanks Leo and GW. You've both been very helpful.

The bottomline is until AND unless I come into a ton of $$$$$$$, so that I can have 2 separate systems in 2 different rooms, I am sticking with what I've got.

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