Buying reciever, trying to use passive sub.

Discussion in 'Beginners, General Questions' started by JohnWohl, Feb 21, 2006.

  1. JohnWohl

    JohnWohl Auditioning

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    Hi, I bought a philips HTS 3400 home theater 'in a box' system. It was cheap and sounds great. It is a progressive scan DVD player with a built in amp (100x6) so the speakers hook right up to it.

    The big problem is that this thing has no surround inputs. I want to run my xbox and my cable tv in surround sound but with no inputs on the philips unit, it seems I am SOL unless i get another receiver right?

    So I have resigned myself to spending another 100-200 bucks on a good used receiver on ebay. The problem is that the subwoofer that came with the philips system is passive and is powered from the unit. I haven't been able to find any receivers on ebay with a powered output specifically for the sub, only line out.

    However all these 6.1 channel units have a powered output for a 3rd rear surround speaker which I don't have. Can I use that for the sub?

    I really want the ".1" surround from my sub, you know.. I want 'correct' surround sound. I have heard of connecting the front speaker outputs to the sub and then from the sub to the front speakers but the sub doesn't have any inputs. I also heard that this wouldn't be the correct '.1' surround and only the low pass from the front speakers.

    I could get a separate sub amp but I don't want to try and run over 100w rms to the sub since that is what it is at now.

    Any suggestions?
     
  2. Lew Crippen

    Lew Crippen Executive Producer

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    Welcome to the forum John.
    No. The audio information for the rear channel is very different from that for the subwoofer.
     
  3. Dave Poehlman

    Dave Poehlman Producer

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    Visual aid (click the pic for a bigger view):

    [​IMG]

    They took the time to put a digital out on there.. but no digital in. Hmmm....
     
  4. John Garcia

    John Garcia Executive Producer

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    Many all in one units that I've seen do not include a digital out. Most likely because it isn't intended to be used as a DVD/CD player only with another receiver/processor.

    John, you ARE somewhat SOL. You can pick up an amp cheap that should be able to handle the sub without issue. You are not likely to find any receivers that have a powered output for the sub, as active subs have more or less become the standard, and most passive subs are expected to have their own amp as well. Ubid had the Audiosource Amp100 for something really low like $60 or $70. You can pick up a cheap Onkyo receiver for around $200 also.

    It really sounds like this system isn't meeting your needs, so I'd almost say just sell the whole thing complete and start from scratch.
     
  5. JohnWohl

    JohnWohl Auditioning

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    So if I get the Audiosource Amp100 im going to want to bridge it to 1 channel? I think the sub is 8 ohms, so how will bridging the amp affect the load? I don't want to blow the sub or anything.
     
  6. John Garcia

    John Garcia Executive Producer

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    Yes, I'd run it bridged. It shouldn't hurt the sub, though it might give you enough power to bottom it out. Plenty of power normally isn't a problem, it is too little that usually causes the problem. you probably will want to keep the amp turned down to a level where it isn't at 100% gain feeding the sub to be on the safe side, but it should be OK.

    Another option would be to pick up a small plate amp from www.partsexpress.com which are designed specifically to drive a sub. I also have a passive sub and I use a plate amp to drive it in this manner. The only downside to this is that many plate amps need something to sit in because they are not self contained and are not "shelf" friendly like a separate amp.

    Take a look at this guy. Just $50 and it looks like it is enclosed.
     
  7. JeremyErwin

    JeremyErwin Producer

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    Look in your manual at the specifications. Find the frequency response.

    For example:

    It is desirable to have the response cover the "full range" of audio frequencies, and be more or less flat. (individuals with more financial resources may choose to cover an even fuller range, but this is quite expensive, especially the infrasonics. A person of more modest means might have to settle for a low end of 25-30 Hz.

    Modern movie soundtracks are mixed in what is popularly referred to as "5.1" sound-- five full range soundtracks, plus a low frequency effects (l.f..e) track-- sometimes referred to as a "boom track." The thundering bass of of a T. Rex's footsteps or the flap of a nazgul's wing goes here.

    The LFE track has a low-end below 20 Hz and a high end of 120 Hz. If your subwoofer's frequency response does not cover the majority of the lfe track, then you are missing quite a lot, and it's probably not worth getting a separate amplifier for this subwoofer. It used to be the habit of this forum to recommend an inexpensive tiny mighty subwoofer from dayton audio/parts express, but the company has since discontinued it, in favor of other models with unknown price/performance ratios.

    Modern receivers incorporate a crossover, which determines which frequencies go to which speakers. Essentially, a user selects the crossover frequency (e.g. 80 Hz), and all frequencies below this value to the subwoofer (plus all information from the lfe channel), and all frequencies above are reproduced on the other five (satellite) speakers. I mention this because if your satellites are incapable of reproducing information below, say "200 Hz", and your new subwoofer has a range of say "25-160 Hz", anything between 160 Hz and 200 Hz will be tossed away. Not terribly pleasant.
     
  8. Charlie Campisi

    Charlie Campisi Screenwriter

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    John already brought this up, but you really should consider selling the system or returning it. You're looking at spending $250 between the receiver and amp just to get a way to get digital audio inputs. It's a patchwork solution an easy problem. Spend $350 for a refurbed Onkyo or Yamaha system and $70 for a budget panasonic or sony dvd player. You'll be able to keep parts of those systems if anything breaks or you want to upgrade other components. You're painting yourself into a corner with the solution you're trying now. No offense. I know people don't like to be told they bought the wrong thing. Just trying to help.
     
  9. Wayne A. Pflughaupt

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    John,

    While you’ve gotten some accurate advice here, it looks to me like everyone has overlooked one obvious option: Get a new receiver, and use the HTIB as the amp for its sub. That’s what my son did when his HTIB crapped out, and it worked fine until he was able to get a “real” sub. The Philips has two pairs of audio inputs, so you’re in business. Just run a cable from the sub out jack of whatever new receiver you get to the HTIB’s AUX or TV input jacks, and hook the sub up as normal. Set up the receiver as you would for a powered subwoofer.

    Regarding what Jeremy said about frequency response, I would hope that the 180 Hz-16 kHz figure is for the satellite speakers. Even the cheesiest HTIB sub should be able to get down to 50 Hz or so. Heck, most any computer sub can do that, and most of them are no worse than a HTIB sub.

    Regards,
    Wayne A. Pflughaupt
     
  10. John Garcia

    John Garcia Executive Producer

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    At first I thought we had said there was no digital out, but looking back at the pic posted by Dave P, there IS a coaxial digital output (I don't know how I missed that), so I think Wayne's is an excellent idea.
     
  11. Wayne A. Pflughaupt

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    Yup, he should be able to use the digital out to send to the new receiver, that way he can use the old DVD player. And the Aux in for the sub. I guess the only mystery is if he’ll be able to use the DVD player (and the digital send) if the unit is set for “Aux” – which it will have to be to use the internal amps for the sub.

    Regards,
    Wayne A. Pflughaupt
     
  12. JeremyErwin

    JeremyErwin Producer

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    Ah. I think I missed the subwoofer portion. Oops.
     

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