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MCACC and speaker size

Discussion in 'AV Receivers & Amplifiers' started by AndyH, Apr 14, 2004.

  1. AndyH

    AndyH
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    Hi,

    OK - bear with me a sec while I ramble..

    Pioneer Ax5i - Tannoy speakers.

    The main fronts are arguably LARGE, the centre while a match certainly is SMALL and the rears are probably LARGE.

    Now, I first ran though MCACC when I got the amp and everything ended up as large - which is how I had things on my old Sony and was happy.

    However, I've come to think its time to revisit the argument, especially with this new auto-calibration toy.

    So I re-ran it expecting to be able to change the speaker size and I can't. It seems to lock everything to LARGE.

    I can change them afterwards, but I'd have thought it more logical to override the speaker size and then calibrate. Not change the calibration afterwards, although I can see the twisted logic here - its what the manual refers to as "Expert" settings.



    Also - setting centre to SMALL and fronts to LARGE: Does the bass from the centre go to the sub, or is it re-distributed to the fronts? The manual implies the latter, but I thought it was the former.


    Any discussion appreciated!!

    Cheers,
    Andy
     
  2. Thunder

    Thunder
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    The bass work will probably be redirected to your sub. Unless you have a monster sub let your speakers do all the bass work they can as most speakers are more agile in the upper bass frequencies than most subs and you will get a cleaner sound. Doing all the bass work for five speakers plus its own .1 channel is a hell of a lot of work for one sub, there is no point having large speakers if your only going to use a limited amount of their frequency response capability.
     
  3. AndyH

    AndyH
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    Yep, agreed- I consider all my speakers as Large for exactly that reason - except the centre, which is small and weedy, so I'd like my fronts to take the bass from the centre.

    I thought it interesting that the MCACC seems to deem my centre as large and I have to override it afterwards.

    My logic would've thought overriding speaker size first, then running auto-calibrate (so it can take into account my tastes) would've made more sense.

    Just interested how other amps do their auto-calibrate (the Yamaha and Denon new beasties), and how people attack this!

    Cheers,
    A.
     
  4. Thunder

    Thunder
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    Well with my Tag you have to do it by hand with a RTA program, sound level meter, PC and some callibration wizard software written by Tag. So Im affraid I cant comment on the automated systems or their accuracy.
     
  5. justinh

    justinh
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    Don't entirely agree with that Thunder.

    Many people run small - even on larger speakers. The bass that does get redirected to the sub is normally very low (80 Hz cross over is typical) - so upper bass is not affected whether your speakers are set to small or large via the Amp.

    The other speakers are then able to purely deliver sound without trying to cope with the very large cone excursions forced on them by low bass. This reduces distortion of the cone and therefore leads to a cleaner mid sound and greater power handling.

    Subs are dedicated to dealing with the low bass and engineered appropriately - at least if you have a good one.

    A good sub may be able to deal with cone excursions of between 1 to 2 inches - normal speakers would often struggle with half an inch. This excusrion combined with the vastly increased surface area of a 12" cone (as opposed to 6 - 8" on a typical speaker) means the sub is in a much better position to deal with low bass.

    Just my thoughts....

    Justin
     
  6. Thunder

    Thunder
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    But whats better 5 speakers doing the work of five speakers at the the frequncy bandwidths they were designed to operate at or one active sub trying to do the work of six speakers on its own? When Tag calibrated my system we tried the speakers as bass restricted to 80hz and at their natural frequency roll off points as defined by the manufacturer. It was like night and day. If you have small satelites then fair enough you dont have much choice, but if you have larger speakers then you should use their full potential. The sub is also the hardest speaker to tame with regards to room modes so it makes sense to let it do what its optimised for which is the very low stuff. Speakers will always produce a cleaner bass sound as their drive units are much lighter and therefore more agile.
     
  7. zoolap

    zoolap
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    On this note is there any pc software where I could connect a mike to the pc and let me calibrate the speakers with my non-mcacc amp. I know there is AVIA, but I've seen some reviews where people say there are tests on there that don't give you any ideas on how to make use of them.

    Ideal thing would be Denon 3805, but that's just too much money for me.
     
  8. ancientgeek

    ancientgeek
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    One good reason for setting all speakers to small is that multiple LF sources at different locations in the room will add or cancel depending on frequency and listening position, producing uneven bass performance.

    It is easier to set all to small and experiment with placement of your sub(s) to get a satisfactory result in all listening positions.
     
  9. AndyH

    AndyH
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    That's a good point.. although I'm forced to have my sub tucked down the side of the settee pointing directly at Front Right :)

    Cheers,
    A.
     
  10. Thunder

    Thunder
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    The bass would only cancel if the speakers are running out of phase or the sound track has been badly engineered. It dosnt change the fact that getting the sub to do the bass work for up to seven speakers is putting a lot more stress on the sub than getting the speakers to do the work they were designed to do. If the speakers are only filling in the frequency band widths they were designed to operate in then you are not putting them under undue stress. The sub always produces the most in room resonances and is the hardest to place without causing modes. If you have large speakers use em to their full potential otherwise there is no point in having them. It would be like buying a bus instead of a car but only ever using the front two seats. If you have frequency restricted satelite speakers then fair enough, but if you have larger speakers then use their full frequency response capability otherwise ther is no point in having large speakers.
     
  11. AndyH

    AndyH
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    *laugh* great analogy "It would be like buying a bus instead of a car but only ever using the front two seats" :)

    Ahh, is all taking me back to my acoustics degree now.. except I have a dumb question around bass management.

    If all speakers are set to large, is it just the .1 channel that gets sent to the sub (for DD/DTS stuff)?

    So.. I should have the crossover on my sub turned all the way up?

    Currently it is vaguely in the middle to fit in with the other speakers, but now I have the pioneer I can set the crossover via the amp - but I'm a little unsure what effect this actually has, i.e. do I have to compromise for Pro-Logic decoding as I did with the Sony amp (which had no crossover adjustment).

    Any good analogies for that? ;)

    Cheers,
    A.
     
  12. Thunder

    Thunder
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    You should give your sub a line feed from your amp without using the crossover in the sub, let the amp handle the crossover in the digital domain. Im not familiar with the pioneer software so cant tell you what freq crossover the amp will use if you set the speakers to large. Hopefully the calibration system should calculate your speakers low frequency limitations and fill in with the sub at your main speakers roll off points. With my Tag you just plumb in the individual speakers roll off points, e.g Mission 783 40hz and the sub fills in anything under 40hz.
     
  13. AndyH

    AndyH
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    Excellent, well I'll try and have a go tonight. The sub does use a line feed from the amp, but the appalingly labelled (i.e. no scale) crossover knob on the sub still comes into play. I guess I just crank it to 11 ;)

    Thanks for the replies, always a good topic for discussion eh?

    (until someone tells you to stop worrying about it and just use your ears :) :) )

    Cheers,
    A.
     
  14. Thunder

    Thunder
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    No probs mate have fun playing.
     
  15. AndyH

    AndyH
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    A-ha... funny how reading the manual after getting used to a product helps enormously..

    From the section on Crossover Network:

    "If all speakers are set to LARGE this setup is unncessary"


    So I guess I do need to whack the crossover on the sub to its highest setting to ensure I'm getting all of the .1 track.

    But this returns me to my question I had with my old Sony... what bass (if any) gets sent to the sub when listening in PLII modes?

    Cheers,
    A.
     
  16. darrens

    darrens
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    Just to help/hinder the debate - I've got an AX3i and an MS 500 THX system and when I did the automated setup it set all the speakers to large (which they are) but then I didn't get hardly any bass going to the sub.

    I set all the speakers to small and then the low bass improved dramatically.

    Presumably, even at large, the .1 channel goes to the sub but I can only assume there's plenty of <80Hz info in the 5. channels and that's what doesn't go to the sub if you set the speakers to be large.

    I don't fully understand it, but a lot of trial and error made me certain that setting all the speakers to small was the best way to go.
     
  17. AndyH

    AndyH
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    Yeah, that makes sense with my current understanding. I'll see how the fiddling goes this evening.
     
  18. Buckster

    Buckster
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    I've done lots of experimenting with my Pioneer 2011 + Front M3s, Rear M2s, and Centre RC, and REL Storm.

    I did have everything set to Large .. but in reality I was missing some of the bass that goes to the fronts in a soundtrack - my M3s go pretty low - but using Avia test tones - I found they roll of very quickly around 70Hz - yes they will go down to 30Hz - and you can hear it - but at a much lower volume.

    Now I've found the following setup best by far.

    Fronts Large
    Centre Small
    Rears Small
    Crossover 80Hz
    Sub Plus or whatever it is called

    Setting the sub to Plus means full range sent to anything large (Fronts in this case) but also anything below Crossover - ie under 80Hz also sent to the Subwoofer. As my front speakers roll off pretty quickly at 70Hz you don't get any bass boom.

    Mark.
     
  19. AndyH

    AndyH
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    Well, I'm impressed... set all speakers to small, crossover to 100Hz and suddenly PLII and stereo material has sprung into life.

    As I thought, 5.1 isn't hugely different as the sub was actually doing something at times. But it is improved as I no longer have a gap between where my fronts were tailing off and the sub picking up.

    My fronts are rated down to 55Hz, but that's pushing it *a lot*, hence going with crossover at 100 for now.

    I'll have a look at the plus option, that's a nice explanation of how that works.

    Cheers,
    A.
     
  20. darrens

    darrens
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    AndyH, the only difference I have is that I set the crossover to 80Hz. That's the THX standard and, since my speakers are THX approved, I stuck with that.

    I did try setting the fronts to large and the sub to plus (which basically sends all the bass to both sub and fronts) but that didn't give me the best sound for my ears. Bass felt a bit uncontrolled and inconsistent.

    However, just fiddle around until it sounds right for you because all our rooms, equipment and ears are different.

    Oh, one more thing. From the MCACC setting I turned up the sub and the surrounds by a couple of decibels.
     
  21. jrpavel

    jrpavel
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    The Yamaha YPAO system found my Kef Eggs to be LARGE; the Egg manual says that they should not be set to large if you want them to last and not distort. I just set them to small and skipped the size detection step of the calibration.
     
  22. Thunder

    Thunder
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    Maybe its down to the fact that my Tag has more comprehensive bass management and lets you set the cross over point individualy for each speaker rather than just calling the speakers large or small, but I definately find in my system that letting the speakers work to their designed frequency response band widths works better, producing a much cleaner sound controlled sound. Of course if your kit is THX then it will be designed with an 80HZ cut off in mind. However Im not a big fan of THX and find that in particular THX Ultra and THX Ultra II post processing just dull the sound quality by rolling off the top end too much. Im still of the opinion however that there is little or no point having big speakers if you dont use them. If your going to cut the freq at 80hz then just buy some stand mounters. My belief in the scale created by larger speakers is reflected in the fact that five of my seven are all floorstanders.
     
  23. Jules

    Jules
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    I agree with Thunder... to an extent.
    Even with my KEF THX23F's and THX45B subs, it is sometimes better with music sources to have the main speakers set to large + sub. It sounds a little 'fuller'.

    BUT, it also depends on the positioning of your sub, and if (like me) you're running 2 subs whether they run in stereo or dual mono mode.
    There is one sub position in my room which really makes the system sing as though the room was full of full range speakers, but its unfortunately totally impractical.

    I'm now on the hunt for THX amplifier that offers split L & R sub pre-outs to deal with this problem more effectively.
     
  24. Thunder

    Thunder
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    If your problem is with modes and integration there is nothing to beat a comprehensive parametric equalizer. I believe the one in the new Yamaha is quite sophisticated and it will run two subs, not too sure about the Pioneer AX10. If not why dont you go the seperates route. Im sure you would be able to pick up an AV32RDP at a bargain price and TMREQ is one of the most sophisticated system calibration systems on the market.
     

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