1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Using a stereo amp for movies

Discussion in 'Home Cinema & Hi-Fi' started by TALON1973, 17 Apr 2020.

  1. lucid

    Soldato

    Joined: 29 May 2010

    Posts: 5,384

    Location: Cheshire

    You've got a headphone rig. How about buying a cheap Optical-to-stereo-RCA convertor (£10 - £15) and having a listen to judge whether lip sync would be an issue.


    For speaker quality, decent stereo speakers do just fine with TV audio. In fact, the better the stereo imaging from them then the less need for a centre speaker & AV amp setup unless you want to make use of the channel balancing and features such as Late Night mode for DD encoded audio.
     
  2. TALON1973

    Mobster

    Joined: 28 Jul 2004

    Posts: 4,716

    Location: llanelli , south wales

    ive got Sony wh-1000xm3 for late night listening
     
  3. hornetstinger

    Soldato

    Joined: 6 Sep 2016

    Posts: 6,965


    You may want to use the speakers sometimes, in which case night mode is useful.

    Personally is stick with a avr, I only have stereo with sub speakers in my upstairs pc system, and I wouldn't change it for a stereo amp. Even if it had hdmi inputs.

    I have option to add extra speakers, maybe use some spare rears for gaming or videos to add some atmosphere. Can't so that with stereo amp
     
  4. TALON1973

    Mobster

    Joined: 28 Jul 2004

    Posts: 4,716

    Location: llanelli , south wales


    Not an option.. I live at home with parents that are 77/78
     
  5. tom_nieto

    Capodecina

    Joined: 18 Oct 2002

    Posts: 10,991

    Location: Birmingham

    The most straightforward solution will be an AV amp of some description.
     
  6. jpaul

    Capodecina

    Joined: 1 Mar 2010

    Posts: 11,324

    agree on HD, but freeview/sky/blue-ray ...? are providing a mixed down 2.0 pcm, or if its a bitstream 2.0, which the tv would convert 'digitally' to pcm, so,
    using the tv circuitry is not going to degrade the audio, more than an AV processor, both just give faithfull passthrough.

    so ... if he's happy with the 2.0 mix, (e: and not needing to remix the voice, like me) then amp with just optical input would be fine.
     
    Last edited: 19 Apr 2020
  7. roadie

    Mobster

    Joined: 22 May 2003

    Posts: 2,694

    Location: Hampshire

    I have a stereo setup in my lounge with my TV connected to a Denon PMA-50 amp via optical. It works perfectly, with the only annoyance being the need to use 2 remotes (1 for the TV and 1 for volume).

    I like stereo setups. The only upgrade I would consider would be a stereo amp with HDMI ARC like the NAD D3045 or Pioneer SX-S30DAB so that the TV remote could control the volume as well!
     
  8. lucid

    Soldato

    Joined: 29 May 2010

    Posts: 5,384

    Location: Cheshire

    I think you might have missed the points, or at least got separate points mixed up with each other.

    The TV downscaling multichannel is a different and separate issue to what with might happen to audio fidelity if - as @stuman was suggesting - we all used our TVs as a source switch for all of our sources.
     
  9. jpaul

    Capodecina

    Joined: 1 Mar 2010

    Posts: 11,324

    ok my post wasn't clear -

    if you use your tv as a source switch, and provide it with sources which are already 2.0pcm (eg from sky/freeview/blu-ray), or bitstream 2.0 at a resolution <96Kb/s,
    will the tv not be fine for accurately feeding/passing that through to it's optical output , without degradation due to internal electronics. ...
    ok I'm perhaps stating the obvious here
    (whereas yes, if you give it an hd bitstream source, that the tv, potentially, mixes down, the optical pcm output maybe degraded)
     
  10. lucid

    Soldato

    Joined: 29 May 2010

    Posts: 5,384

    Location: Cheshire

    The problem here is that you're making a whole bunch of assumptions; stuff like all TVs work to the same quality, and that all our sources use HDMI, and that those sources are good enough for high-quality audio-only replay via a HDMI-to -optical chain chain that @stuman thinks is suitable for everyone. I'm saying that that's not the case.
     
  11. stuman

    Wise Guy

    Joined: 27 Aug 2003

    Posts: 1,670

    The OP has a budget of ~£300 for an amp.

    now, take that £300 and split it through 5 amplifier stages. Then the licence fees for DD, DTS etc, provide a DSP of some kind and loads of electronics to do the switching. You’re left with pittance to put into each channel.

    What needs to be considered is; will the “lossless” codecs being decoded at the receiver end be more audible through the cube speakers or will the greater quality of the 2 channel amp / DAC with down mixing happening transport end provide a more resolute experience. (My money is on the later, but your mileage may vary).

    some people may require all manner of inputs and specialties, but most I would imagine, will be more than catered for by a modern amplifier and tv.

    Edit: thought I’d mention that the amp the OP posted has digital inputs (DAC) inbuilt.
     
    Last edited: 19 Apr 2020
  12. TALON1973

    Mobster

    Joined: 28 Jul 2004

    Posts: 4,716

    Location: llanelli , south wales


    Ok I need to clarify something... musically I don’t really care. I’m trying to get something that’s better than the Sonos beam. I picked the cube setup as it was literally £125 for 5 speakers and a sub brand new ( it’s still available if you look online ).
    I won’t be using all 5 speakers, but I’m trying work out what’s best for me in my budget for general sound.

    if you actually check my sig that will show what my main hifi rig is. Which is right next to my seating position in the corner of my wall.
     
    Last edited: 19 Apr 2020
  13. hornetstinger

    Soldato

    Joined: 6 Sep 2016

    Posts: 6,965

    Unless you spend £1000+ on a av amp, they're crap for power anyway.

    Regardless a 7 channel £400 avr will give you plenty of power with two channels driven, it's just once you connect all 7 power plummets.

    Since op doesn't care about sound, convience and connectivity could be more useful than put and out sound quality. The reason why I chose a avr over a arcam integrated I have already.
     
  14. stuman

    Wise Guy

    Joined: 27 Aug 2003

    Posts: 1,670

    To me music and movies are the same thing.

    so in my opinion the amp you spotted is a great choice. Your current setup looks great as well so you know what 2 channel can sound like.

    I’m biased.

    The amp is available on Amazon so you could get it with prime, have a listen?
     
  15. TALON1973

    Mobster

    Joined: 28 Jul 2004

    Posts: 4,716

    Location: llanelli , south wales

    That's slightly over simplifying what I said. I'm not fussed on it on the musical side. I'm not totally happy with the beam. The mission speakers came up and I fancied something different. I wasn't prepared to buy the sonos sub.

    I want 2.1 or 3.1 max at this moment in time. If my circumstance change I'll have the spares.
     
  16. lucid

    Soldato

    Joined: 29 May 2010

    Posts: 5,384

    Location: Cheshire

    The limiting factor with either solution is going to be the speakers. If it's the Mission M3 kit you've got, then they're designed as AV speakers rather than miniaturised Hi-Fi speakers + sub, so I wouldn't spend too much time worrying AV amp versus stereo amp, particularly as it's mostly for TV use and a "4K player" which I'm guessing could either be a streamer or a disc spinner.

    For the sake of clarity (no pun intended), a stereo amp will have the edge sonically of course. But whether you really hear much of a difference once everything else is taken in to account is very much a different question. What's perhaps more important is the sound from either should give the Beam a decent kicking.

    What it comes down to then is the rest of the package. That means what it's like to live with day-to-day.

    The Denon will get its signal from the TV via Optical, so there's no control signal via that. It has a remote control, but as a Hi-Fi amp it's very unlikely that the remotes from any of your other devices will speak "Denon PMA-600" IR code to operate the volume. You'll also need to remember to turn down TV volume all the way before using the amp. The TV won't do this for you automatically. Neither of these things might be that big a deal for you, but it's a PITA to find out these wrinkles after you've made a purchase.

    An AV receiver, particularly one with HDMI ARC (as long as your TV is compatible) can be set to use HDMI control so that volume is unified, so is power on/off, and maybe input sensing too.

    Setting up the AV receiver, you have the option to go 2.1 or 3.1. The receiver will adapt to the speaker configuration and deal with any rear channel info accordingly. This brings us back to speakers, and specifically speaker positions in your room.

    The BMR drivers in a M3 kit are reputed to have a fairly wide dispersal compared to more conventional Hi-Fi speakers. That's really useful when you can dot the speakers in the locations where you want sound from, but the Achilles heel is their relative inability to create a convincing stereo image. That's quite important if you've got the speakers hooked up to a stereo amp and hoping that they image well enough that voices sound like they're coming from the TV rather than the speakers 3ft either side of the screen. This is where having the ability to run a centre channel speaker pays off.

    Other AV advantages -
    * the facility to tweak the centre channel volume relative to the L&R to give a bit more prominence to dialogue if required
    * retaining DTS and HD audio if routed through the receiver first and so avoiding the downscaling bottleneck of the TV
    * Night Mode

    Now let's talk about power (Hornetstinger's 2nd favourite topic because he owns power amps)

    No AV receiver will match the colossal power of big power amps. Neither will a £400 integrated amp, so let's forget these impossible comparisons. Both the AV receiver and the stereo amp will have plenty-enough power for what you need, and that's really all that matters.

    The Denon sucks a maximum of 190 W from the wall socket. That's its consumption power rating. The speaker power output is given as 45 W in to 8 Ohm (20 Hz - 20 kHz, T.H.D. 0.07%). That's fairly conservative but realistic. The low THD tells us that the amp isn't working that hard, which explains the difference of 100W between the balls-to-the-wall maximum of 190 W compared to ticking along 90 W combined.

    Now let's look at a £300-ish AV receiver. A Pioneer VSX933 was the first I found closest to that price point. Its max power consumption is 450W. It has 7 channels of amplification.

    Pioneer rather optimistically rate the amp at 135 W/ch at 6 ohms, 1 kHz, 1 ch driven of 1% THD, but that's a bit of a work of fiction. 1kHz is a test tone, and who listens to test tones? 1% THD isn't a disaster, but the amp is working a bit harder than the Denon's 0.07% THD. 1 channel driven, another cheat: We can't expect the amp to sum up all its power from the transformer and capacitors and stuff it in to a single channel. It would blow the output transistor pair for that channel, but running one channel rather than two probably gives a 10-20% helping-hand to what the amp would deliver in stereo mode. The other cheat is measuring at 6 Ohms. The 8 Ohm measurement would be closer to 100W, all else being equal.

    Working things back then, the Pioneer is probably pushing 30-35 W/ch in 7 channel mode measured in a like-for-like way with the Denon. That gives us a combined power output of 210-245 W. If we say that the amp is running in stereo though, and we take a 10% contribution from the remaining undriven 5 channels, then we can top-up our front channels to 45-52.5 W. What was the Denon again?

    Before there's a huge outcry and wailing and gnashing of teeth, I'm going to throw a hand grenade in to my own argument and remind everyone that the PMA-600 will have a better quality transformer (both are ELs but still) and I dare say there's more microFarads of capacitance in the Denon, o it can probably deliver a bit more current swing. But.... the power disparity between a reasonable AV receiver and a stereo amp isn't the disaster some would like you to believe.

    How much power do we actually need?

    The Mission satellites are rated at 86dB/W/m. That means they're kicking out 86dB of sound when measured from 1 metre away and fed with just 1 Watt of power.

    Reference level for cinema sound is 90dB. To hit that with a speaker rated at 86dB/W/m would require 2.5W. With either amp, we have a lot more power on tap than 2.5W. Okay, it's hand grenade time again. Sound dissipates over distance, so the amount of power required will increase. If you're sitting 3m away from the same speaker, then to hit reference level at that point requires 25 Watts for that channel. However, we're not finished.

    Playing two speakers together means that the sound pressure level combines, so we need less power. We need about 12W per channel in stereo mode. We get another helping hand when we add the boundary effect from the back wall a couple of feet behind the speaker. Now we need about 6W/ch. Add a centre speaker and our power requirement drops to 4W/ch

    It turns out then that we don't really need that much power to make a decent sound level. I'm going to throw in yet another grenade and remind you that speakers aren't a static load and having some extra power for headroom is never a bad thing yadda yadda yadda. However, all things considered, an AV amp would do okay for what you need.
     
  17. jpaul

    Capodecina

    Joined: 1 Mar 2010

    Posts: 11,324

    Another, perpetual dilema about amp choice, and, maybe, prioritizing music quality over convenience
    ... is it better to get a £200 amp, and a £100 dac, or the economy of scale of taking an integrated product wins out.

    how much, if any, do power needs increase for driving speakers at low frequencies ? (before you get into the active subs range)
    if, the ear needs more power to perceive the same volume there, and/or the speakers are less sensitive there,
    bigger capacitors/ch in the denon might help, but, that cap values not explicitly in the amp specs, maybe its part of THD at low frequency.
     
  18. lucid

    Soldato

    Joined: 29 May 2010

    Posts: 5,384

    Location: Cheshire

    That's a valid question if we're discussing how the initial sensitivity figure is measured. The dB figure will be different for 1kHz compared to white noise and compared to pink noise.

    However, once a manufacturer gives a figure, then the relative power level changes will be consistent. That's the whole point of dB figures.

    The point of measurement with test equipment is to remove the subjectivity of human response.

    The size of the caps won't make any appreciable difference when the speaker is emitting a test tone for measurement. The amp is in a steady state, and raising a potential difference across the speaker terminals (2.83V @ no load for the 1W measurement), and that's well within the capabilities of all but the lowest-powered stereo amps.

    The size of the caps helps with the changing current demands from the speaker (in Amps, for class A/B amplifiers) when playing real music. The benefit then is in transient response rather than steady state mode.

    If the speakers weren't a BMR-based sub-sat system designed for movies...... but the thing here is that they are. Ultimately then, they're the bottleneck, so speculation on intergrated DAC versus external DAC for a £300 budget is pretty pointless.
     
  19. hornetstinger

    Soldato

    Joined: 6 Sep 2016

    Posts: 6,965

    I have a old av pre amp, integrated amp, and power amp to use with my pc systems. Plus a hdmi switch. Major pain is the ass to use. Had to switch input on av pre, set level on integrated and input, then switch hdmi input.

    Avr replaces four boxes and far easier to use.
     
  20. TALON1973

    Mobster

    Joined: 28 Jul 2004

    Posts: 4,716

    Location: llanelli , south wales

    Mission M-Cube+SE is the package