Newbie here and a question!

Discussion in 'Archived Threads 2001-2004' started by Tony Novacek, May 28, 2002.

  1. Tony Novacek

    Tony Novacek Extra

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    This is my first post here, so hello everyone!
    You guys will probably think I have a "low end" home theater but I am only 16 and don't have a job yet, so its good enough for me [​IMG]. I didn't have much of a choice with some of my equipment either. So here is what I got:
    - RCA RT2500 - I gave my grandmother $250 to add toward a home theater for my Christmas gift and this is what she got me. I actually think this is pretty good for how cheap it was. I'm happy with it.RCA RT2500
    - Panasonic PV 966h VCR - Birthday Gift
    - RCA DVD Player
    - PS2 - also use this to listen to music until I get a CD Player.
    - Sylvania 27" TV - I'm going to upgrade this one day when I get some money [​IMG].
    - I upgraded me L/R Front speakers with a pair of MTX AAL212 speakers.
    MTX AAL212 Speakers
    Then I moved the original front RCA 2 way speakers to the the rear because the original rear surrounds didn't have any tweaters.
    After I upgraded my speakers I noticed a big difference in sound and I love it! There is a problem though. How come only certain parts of my room have good bass? I figure that with 4 12" woofers and the original subwoofer, the whole room should be filled with pounding bass. Only a couple of spots sound real good (like the corners of the room). Could any one tell me why it is like this?
    Is it possible to put one 12" MTX car sub in each of the speakers for more and clearer bass? Would it sound any better? Would it even work at all?
    Another thing, my reciever puts out 100x2 in stereo mode. My speakers handle 300 rms & 600 total at 8 ohms. How come I can only turn my reciever up to about 35 out of 70 before it starts to sound bad while listening to music? I thought I'd be able to turn it up all the way since my new spaekers handle 300 watts rms and 600 total.
    Thanks for any help, sorry so long too!
     
  2. Neil Joseph

    Neil Joseph Lead Actor

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    Welcome to the forum Tony.
    What you are experiencing are room nulls caused by the subwoofers cancelling each other out. When you have multiple subs, placement is critical and difficult. If you have 4 subs to place, it will not be easy, and what I have to tell you may or may not work depending on your room. Take a read through this thread about sub calibration/placement to see what I mean. What you could try to do is ...
    - run with the main subwoofer only (plus your other main speakers of course)
    or
    - place all 4 subs up front (2 on each corner)
    or
    - Place 3 subs up front (2 in one corner, 1 in the other) and 1 sub at the back but you will have to move them around until you achieve the desired results in the listening position.
    or
    - Use less than 4 subs, perhaps 2 subs (1 in each front corner, or both in same front corner, or 1 in front left corner and 1 in rear right corner etc)
    Add to that the need to properly calibrate the subs and the rest of your speakers. It gets complicated with 2 subs, let alone 4 subs. What are the dimensions of the room?
    Regarding the second question about 2 channel music sounding bad at 35%, it could be that you have muddled bass due to all those subwoofers. Why don't you attempt to run with the single subwoofer for starters and see how that sounds.
    Let us know
    I'm moving this to the speakers section fo the forum where the sub experts can help as this will undoubtedly be technical.
     
  3. Michael Lomker

    Michael Lomker Stunt Coordinator

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    The reason that you can't turn up your amplifier is because of distortion. Your amplifier might be rated at 100 watts but that doesn't mean it'll sound good at that volume. My $1200 receiver is only 80 watts but I can turn it all the way up if I want to. That's one of the differences between high-end and consumer equipment (often called mid-fi by the magazines).
    As you progress in your pursuit of audio equipment you'll come to realize that the numbers that manfucturers spout about their equipment has little to do with how they sound. There are some tube amplifiers out there that only make 13 watts but they cost a fortune and sound incredible with the right speakers.
    Your bass problem has to do with room acoustics. Some day you will spend $5-10k on a fancy stereo system and then you'll discover that it sounds awful in your room but great in the high-end audio store. Then you'll spend $1k's more adding room acoustic treatments to "fix" your room. There is a lot you can do at low cost just by moving your sub/speakers around until they sound good. Unfortunately they often sound good in an incovenient location....like in the middle of your walkway or something like that. That's why audiophiles need to have tolerant spouses. =)
    I just finished reading this book and I'd strongly recommend buying it or finding a copy at a library:
    http://www.amazon.com/exec/obidos/ASIN/0964084945
     
  4. Tony Novacek

    Tony Novacek Extra

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    Neil,
    I understand what you are saying, but I don't have 4 separate sub woofers, only one. I have 4 12" woofers all together (2 in each front speakers). Here are a couple pics:
    [​IMG]
    [​IMG]
    I just snapped these pics real quick and shrunk them a bit. Don't mind the dust and the wire mess...lol.
    Sorry if I confused anyone!
    Michael,
    I also understand what you are saying. I'm going to go and check if I can find that book at the library.
    Another thing I forgot to mention in my post was speaker wire. Is bigger (higher gauge) speaker wire better than smaller. The speaker wire i'm using now is real thin and I was wondering if that would make distortion at higher volumes or make any type of bad sound?
    Thanks for your help guys!
     
  5. Bryan_G

    Bryan_G Agent

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    You don't have enough power. That receiver is not enough to run those 4 12"s. If your set up starts sounding bad at 35% your amp is clipping this can and will cause damage to your speakers. Under powering is just, if not more, dangerous then overpowering speakers. All in one systems usually don't work very well with anything other then what they come with. I would recommend getting yourself a nice amp or receiver. You should also think about priorities. I don't think you need 4 12"s in that room. You could have a much better sounding, and more appropriate system composed of smaller drivers and maybe a sub. This however is just my opinion.

    If you look in used gear you should be able to find a nice receiver for
     
  6. Dan Hine

    Dan Hine Screenwriter

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    Bryan,
    I agree with you to an extent. But the size of the drivers do not necessarily mean that they require too much power. The specs on the MTX speakers in question show it as an 8ohm load with a 93db sensitivity which should easy to power. These speakers should be able to be run well with most receivers, even ones that cost $200 or less! In fact I have a spare Technics that I'm sure could do it.
    I think the problem lies more in the pure inadequacy of the receiver rather than the heavy load from the speakers. IMO Yes Tony needs more power but not because the speakers are so demanding. Rather he needs more power b/c the RCA receiver isn't giving him jack. Looking at the rated specs of the RCA receiver it says 100 watts at 6ohms @ .9% THD at 1khz! Hardly worthy of being called a home theater receiver.
    NOTE: Tony, I am NOT trying to be negative about your receiver. We all start somewhere and the simple fact that you've come searching for help and being polite speaks volumes about your character. Your desire to learn more will no doubt bring you into much better equipment and home theater bliss in due time.
     
  7. EricHaas

    EricHaas Supporting Actor

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    Tony:

    Are your speakers set to "large" or "small" in your receiver? You understand the difference is that with all speakers set to small, the subwoofer does *all* your bass and the other speakers do the mid range and highs. Set to large, your speakers are full range and do their own bass, and the subwoofer only does the special Low Frequency Effect (LFE) channel that is the ".1" in your 5.1 setup. Generally, it is better to set your speakers to small, unless your sub isn't the greatest and you have speakers with good bass punch. You might try experimenting with that "large/small" setting. Also, try moving your subwoofer around to various places, especially to a corner position. My guess is that sub of yours doesn't go much lower than your front main speakers, if at all. I also agree you need a new receiver.

    Your upgrade priorities should be receiver first, subwoofer second. Target a used or refurbished Onkyo tx-ds595 or Denon 1802. You can probably get one for under $300. For a sub, pick up the Sony SA-WM40 online for $135. It will blow away what you have now. You'll be in bass ecstacy. You don't have to do these upgrades now, but these are the ones to do when you have the money.

    Good luck.

    Eric
     
  8. Bryan_G

    Bryan_G Agent

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    Don
    Yes I agree. After rereading my post I could see where you got that though. I think you did a nice job of clearing things up [​IMG]
    I didn't even think of that fact that the receiver is probably putting everything below 120hz or maybe even higher to the smaller rca subwoofer. This would be a problem. You should check your receiver for crossover settings, and completely disable it for mtx's.
    -Bryan
     
  9. Drew Eckhardt

    Drew Eckhardt Stunt Coordinator

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    1. Sound waves will reinforce (constructive interferance) and cancel (destructive interferance) each other at various places in a room, with the number of problems going up as you add speakers. One or more sub-woofers in the same corner of the room mated to main speakers with a steep cross-over arround 80Hz will have the fewest problems.

    Scrapping the original sub-woofer is likely to improve things here.

    2. You won't get cleaner and clearer bass from replacing speakers to your existing enclosures unless the new drivers are a good match for the thiel-small parameters of the enclosure. Adding drivers will change the impedance (which may over-heat your receiver) and cause severe frequency response problems. Car sub-woofers generally don't offer low bass (they rely on cabin gain to do this) and are relatively expensive.

    3. Amplifiers attempt to apply some fixed gain (multiplier) to the input signal although there are limits to how positive or negative the output can be (some small distance from the corresponding power rails) and when the gain would cause the output to exceed these limits it gets clipped (look at the wave on a scope, and you'll see the top has been chopped off).

    This does not sound good and will fry tweeters.

    Pre-amp/amplifier combinations and receivers must have more than enough gain to produce a clipped output with a higher input signal because otherwise they would be unable to play lower voltage sources at full volume.

    IOW, it's normal, will break things, and you don't want to do it.
     
  10. Allan Jayne

    Allan Jayne Cinematographer

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    >>> This does not sound good and will fry tweeters.
    Yes. Take heed. If the sound starts to sound different and bad as you turn up the volume, quickly turn it back down and keep it down.
    Speaker systems are rated for so many watts but based on sounds heard in everyday life (excluding electronic music and music with lots of electronic produced special effects), which does not have all that much high frequency energy within the total number of watts being fed in. When the amplifier is overloaded, the "clipping" results in material with a much higher proportion of high frequencies and the tweeter can't take it even though the total number of watts is less.
    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     
  11. Neil Joseph

    Neil Joseph Lead Actor

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    Ah! Thanks for the pics. Now I understand the situation.
     
  12. Tony Novacek

    Tony Novacek Extra

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    Thanks for all the responds!
    Starting to get a little worried here, am I going to break something? [​IMG] I have had this setup for like a month and a half and everything has been fine, except for the bare bass spots. For example: if I sit on the end of my bed (where everyone happens to sit when I show them my stereo), I can feel the bass, but can't here much of it. Then if I scoot back against the headboard and over to the right side, i'm in bass heaven. Do you get what i'm saying. As far as my receiver settings go:
    Front L/R - Large
    Center & Surrounds - Small
    Subwoofer - Yes and is set to + phase
    Center channel - 10 out of 10
    Front and Rear Speakers - 8 out of 10 (when I listen to music in bypass mode, I turn the front up to 10 out of 10)
    Subwoofer - 10 out of 10
    Treble - 10 out of 10
    Bass - 10 out of 10
    Speaker Distance - Front & Center: 8 ft.
    Rear Surrounds: 6 ft.
    And the preset equalizer is set to rock (sounds the best).
    So do my settings seem okay or do they need changed?
    Don't get me wrong though, when I have the volume up to 35 out of 70, it isn't real quiet or anything. [​IMG]
    I will upgrade my receiver before anything else, but I don't think it will be anytime soon.
    As for the BIG speakers: I was looking at some cheaper ones at hhgregg and they didn't have them in stock. There policy is if they don't have what I want they got to give me the next best thing. So these happened to be the next best thing because they didn't have much in stock. So I walked out with almost $600 speakers for the low price of $150. So if anyone is wondering why this kid has such big speakers in that small room and connected to such a bad receiver, I just couldn't pass up such a good deal! Plus I will have them for when I get my own place in a couple of years.
    Thanks for all the help guys, still open for any ideas.
     
  13. kevin_tomb

    kevin_tomb Stunt Coordinator

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    Sounds like your home theatre receiver is just very optimistically rated. Its rated at 100 watts at just one frequency, which means at lower and possibly upper frequencies it may not have nearly as much power. For a power rating to be meaningful it must state :watts per channel and a frequency limit of at least 20-20,000 Hz. Also a reasonably low amount of harmonic distortion. .9% is very high. Most receivers are rated at about ten times less than that. Your "true" output must also be measured at 8 OHMS. The 6 OHM measurement is misleading and makes it look more powerful than it it. Just as a guess Id say your "true" rating may be closer to about 30watts per channel with a decent amount of distortion at a full frequency range and at an 8 OHM rating. Dont be disapointed........Most entry level equipemnt overrates and uses poor test methods to make their devices "seem" more powerful than they are. I have a 20 year old HARMAN KARDON receiver rated at 20 watts per channel and it amazes everyone how it "PLAYS AS LOUD AS A 75-100 WATT model" of course thats in comparison to stuff thats not rated correctly im not talking high end equipment
     
  14. Shawn_S

    Shawn_S Stunt Coordinator

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    Try Swaping your left main and your sub. Try placing the sub in the left corner and move your left main beside the TV like your right main is. This may give you more consistent bass for your room. You may also want to consider a calibration disc like Avia or Home Theater Tune-up
     

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