Denon 3803 is clipping out...Why?? Please HELP!

Discussion in 'AV Receivers' started by Jason Cheung, Oct 24, 2003.

  1. Jason Cheung

    Jason Cheung Agent

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    I'm a HT noob. I need help...please!

    Here's my system:

    Fronts: B&W 801's
    Centre: B&W HTM-2
    Surr: B&W CDM-SNT
    Sub: [None just yet]
    Receiver: Denon 3803
    External Amp (powering the 801's): Audio Research VT-50

    My room is about 20ft x 9ft x 10ft

    Here's the problem:

    After calibrating the speakers and setting the Bass tone up to +10dB (and subsequently at +6dB), while watching scenes from Matrix Reloaded, the 3803 clipped out. I don't have a subwoofer, and my friend (who knows a little more about this stuff) said the surrounds and possibly the centre needs more current.

    The surrounds (B&W CDM-SNT's) have a minimum of 4.8 ohms. The HTM-2 centre has a minimum of 4.6 ohms. But the Denon 3803 is only capable of 8 ohms...or 6...I'm not even sure!

    Basically, my friend told me the 3803 is not providing enough juice to the surrounds (and possibly the centre). The first suggestion he made is to get a new receiver, one that can put out 4 ohms. Another possible solution is to get external amps.

    I wonder if putting in a subwoofer would solve this problem. My friend said the surrounds may be handling a lot of bass, and so causing the receiver to clip. My thinking would be to finally get that subwoofer (I've been meaning to get) and to see if this will solve the clipping problem.

    Is this a good solution, or would I just be better off improving the receiver or getting into separates altogether?

    I know there are a lot of possibilities...but I just don't know what those are. Can you suggest some...give me options, even some products that will go well with my speakers?

    Thanks...

    Dazed and confused,

    Jason Cheung
     
  2. Marty Neudel

    Marty Neudel Stunt Coordinator

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    Jason,

    the subwoofer may help, but it's a long shot. From your description and from the specs on the 3803, the amps in your receiver just aren't capable of driving your surrounds.

    Remember that each time your amp goes into clipping, it is very likely doing a small amount of damage to your speakers. I would try new amps for the surrounds, QUICKLY.

    Marty
     
  3. Chuck Kent

    Chuck Kent Supporting Actor

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    From a very basic standpoint, clipping is a function of a speaker's sensitivity and an amp's power output capability. But impedence can affect the amp's output capability (in general, receivers are more vunerable than standalone amps), along with what volume you are trying to achieve at your listening seat (which relates to room size.)

    One other thing worth noting is that many speakers (not all by a long shot) are at their lower impedence levels at lower frequencies. So, if you are driving the center and surrounds as "Large", then this will exacerbate your troubles. As a temporary solution, set the center and surrounds as "Small" and the crossover to at least 80Hz. If you're still having volume troubles, try 100Hz. The key is to reduce the level of the frequencies that use the most power from your receiver (the bass.) (Of course, if they were already set as "Small", just check the crossover frequency and try setting it higher.)

    If the "Small" setting makes a real difference, then adding a sub should work as well (since you'll make it the destination of the bass you'll be redirecting from the "Small" center and surrounds.) IMO, a sub is necessary for movies anyway. I realize that budgetary (or space) considerations are often the reason many of us don't initially buy subs. But movies are mixed as 5.1 (or sometimes 6.1) and even though the Denon can "remix" 5.1 to 5.0, your HT won't produce sound to it's fullest potential until you have a sub (the .1 Low Frequency Effect channel from it's own speaker.)

    But, after all this, if things are still dicey, then it looks to me that are you going to have to move to a better receiver or more external amps.

    Let us know how it goes. Good Luck!
     
  4. Mark All

    Mark All Second Unit

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    Jason,
    I see a couple of problems with your current configuration. You're trying to drive low impedance speakers with a receiver's amplifier that doesn't have a power supply engineered to do so on demanding soundtracks. I'd recommend just using your receiver as a preamplifer/processor and not using its amp section at all. Lots of people, including me, use the 3803 this way. I'd recommend using a Rotel RMB-1075 or similar high current 5 channel amplifier. It is fully capable of driving a full set of 4-ohm speakers by itself.

    Your system should work okay this way, but you really do need a subwoofer as well at some point in the future. Having to set your bass tone control anything above flat on the receiver tells me that you like bass. Matrix Reloaded has lots of LFE effects. With the combination of the hot LFE effects on the DVD, 4 ohm speakers, and the boosted bass you've been seeking, it's not really surprising that your receiver started clipping. Check out one of the SVS box subwoofers for a great deal.
     
  5. Jason Cheung

    Jason Cheung Agent

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    Marty, Chuck, Mark, thanks for the help thus far!
    It's always good to know there are people out there willing to help out...thanks.

    Marty, the fact that I may be damaging my speakers by small amounts, increases the urgency with which I want to solve this problem. I'll consider this seriously.

    Chuck, your explanation and suggestions are very helpful. At present, I am already setting my Front's to LARGE, my Surrounds and Centre to SMALL and I and still clipping out. I believe the crossover is already set at 100 Hz...at least 80. Would setting this higher also help, if even a little?

     
  6. Chuck Kent

    Chuck Kent Supporting Actor

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    Jason: If you already have the center and surrounds set as "Small", and have tried the crossover at 100Hz and you're still having troubles, then the need for an external amp handwriting is on the wall.

    The crossover in the 3803 can go as high as 120Hz but I'm no fan of going above 100Hz (especially since the speakers you're using are capable of playing a fair amount lower than that.) (IOW, you'd be "skipping" some bass from them that they are really capable of.)

    I don't have any experience with the Rotel amp Mark mentioned. Still, that said, Rotel, Adcom, NAD, Outlaw and such all make affordable products worth looking at.

    I myself use a 3803 with an older (but still working peachy) 5 channel Carver amp. I've been very pleased with my setup. But you certainly have a point in that a separate pre/pro makes a lot of sense. For me, I wanted the features that the 3803 offered (not to mention that I just plain like Denon.) I just didn't see anything at the 3803's price range that I felt would be a better choice for me.

    In the interim, I guess I'd still go ahead and (biting my lip) run the crossover up to 120Hz. At least this will be doing the most you can do for now to protect your speakers...
     
  7. Mark All

    Mark All Second Unit

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  8. CurtisC

    CurtisC Second Unit

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    Somethin' ain't right,bass tone at +6? My 3803 drives 4 ohm speakers to deafening levels (21x24 ft room)with ease,tone set flat.
     
  9. Chuck Kent

    Chuck Kent Supporting Actor

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    Funny how one can read a thread and totally miss something that could be fairly important...



    (Thanx Curtis for pointing this out!)

    As much as I have learned about Denon receivers, one thing I don't know is if the tone controls only affect the main left and right channels or if they affect them all?

    I suppose that experimentation could give us that answer. But for now, lets assume that the tone controls do affect the center and surrounds.

    If sufficient power is an issue (and it's pretty clear it is), then running the bass up to plus anything is only going to make things worse. Every 3 decibels of volume increase requires twice as much wattage from the amplifier.

    Even though the crossover in the Denon should be filtering out lower bass from the center and rears, running up the bass would be counteracting the actions of the filter.

    Jason, try setting the bass back to flat and the crossover to 120Hz. Let us know if this makes any change in how loud you can safely go...
     
  10. Mike Sloan

    Mike Sloan Second Unit

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    Your driving 801's with a 3803? Thats a recipe for disaster...you will fry the voice coils in your speakers by running your amp into clipping! You absolutely need to get a stand-alone amp...like the Outlaw 770. The Pre-amp section in the 3803 is a good one....many people use it as a Pre/Pro to control a sepparate power amp. Even Denon recomends this when driving "full-range" speakers....even crossed over at 80hz! I see that others have said the same thing above. I, frankly, think it's crazy to drive the speaker compliment you listed with the 3803. I have the 4802 and am driving smaller speakers and am switching over to the Outlaw 200W monoblocks for this very reason. I will further recommend purchasing a robust sub (SVS PB2+) and setting all speakers to small/80hz...even those beefy 801's. The Sub will provide better quality bass in the 80hz and below range than even the 801's...plus the added benefits of co-locating which has been discussed in depth in older threads.

    You will damage those "beautiful" speakers if you don't act quickly!!!!!!!!!!!![​IMG]
     
  11. keir

    keir Stunt Coordinator

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    here's from denon's faq.
    [rant]9) CAN I USE 4 OHM LOUDSPEAKERS WITH MY DENON RECEIVER OR POWER AMPLIFIER?

    Yes, you certainly can.

    To understand this a bit better, first realize that all amplifiers are designed to deliver a signal into an electrical "load" or resistance presented by the loudspeaker. We measure resistance in units called "ohms" (after the German physicist Georg Simon Ohm, 1787–1854).

    Conventional wisdom makes an 8 ohm loudspeaker load the most acceptable because it "protects" the amplifier from delivering too much current. A 4 ohm loudspeaker can encourage a marginally designed amplifier to deliver more current than it comfortably can.

    However, you should remember that a loudspeaker’s impedance rating is a nominal or average one: A speaker rated at 8 ohms may actually vary from 5 (sometimes even less) to 20 ohms or higher, depending on the frequency at which you measure the impedance. (Don’t worry about this too much -- good speaker engineers are well aware of these variations and take them into consideration when designing products.)

    In general, you’ll find that Denon products are designed to function with a wide variety of loudspeakers and have power supplies and output circuitry more than able to meet the current demands of low impedance loads.

    In the rare event that very low impedances tax the amplifier, quick acting circuitry will protect it from damage. If unusual operating conditions trigger this circuitry, the word "PROTECTION" will appear on the unit’s front panel. If this happens, simply turn the unit off, wait a moment or two, and turn the unit back on again. The protection circuitry will automatically reset. If it re-engages, check your system for possible malfunctions. [/rant]




    also, with a setup like this especially, you should really never be using the tone control, especially at +6 bass! thats pretty outrageous setting really. it wont sound anything near accurate either. a sub should definately improve the max output capability of your setup. if you're setting all speakers to small and leaving the tone control flat, i dont see how you would not be getting some loud, undistorted sound. 91 dB sensitive speakers dont exactly require a lot of power to get loud.
     
  12. Jason Cheung

    Jason Cheung Agent

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    Wow, I didn't expect all this help! Thanks. I mean it.

    Mike Sloan, I'm afraid you misunderstood my current set up. I have my 801's driven by an external tube amplifer (Audio Research VT-50) and the Denon is powering the centre and surrounds.

    But, reading your post again, I'm not sure whether you think my "recipe for disaster" is refering to the Denon driving the HTM-2 and the CDM-SNT's. If this is the case, is this really a bad match? Is the 3803 not a good receiver to power these speakers?

    I really don't know, can someone give me input on this?

    I'm asking because, from what I'm learning from your help, I'm considering buying a separate amp to power the centre and surrounds. My reason is because I'm hearing that I need a high-current amplifier that is capable of powering 4 ohm loads. That's why I was considering the Rotel 1075. (Ouch...$$$$).

    However, Keir's post (and the cut from Denon's FAQ) was very helpful. Thanks.

    But, I wonder if Denon had in mind 801's when talking about "loudspeakers."

    Regardless, I will definitely turn down the bass tone level back to 0 (and set the crossover frequence to 120 Hz: thanks Chuck, I'll try it out), since setting it higher wouldn't sound "accurate" (thanks Keir).

    Again, I'm a noob when it comes to this stuff. ALL your input, and I emphasize ALL, is very important. I also recognize that, even with this problem, there are varying views. I'd like to hear any more suggestions you might have.

    I guess I can leave you with another question:
    Should I aim to purchase a sub first: SVS pb2+ sounds good.
    Or should I get the Rotel RMB-1075 first?

    My thinking is that if I get a sub to handle the low frequencies, I might not be having the clipping problems with the Denon. What do you think? Is this "good" thinking?

    Or do I need to get the Rotel 1075 eventually, anyways?
    (I guess what I'm wondering is, is the 3803 capable of driving the surrounds and centre?!?)

    Sigh...

    Well, thanks for reading and helping.

    Cheers,

    Jason
     
  13. Mike Sloan

    Mike Sloan Second Unit

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    I am sorry Jason...I did assume you were driving the 801's with the 3803....that's why I freaked a little in my response....sorry. You definitely want to run the speaker compliment...all small and utilize a sub like the PB2+. It is surprising that your Denon is clipping and is only powering the center and rears. Still the HTM2 is better served running 80hz and above. I have the HTM1 and I run it small! Jason....check out the Outlaw 200W monoblocks. They are $299.00 each and I think they are running a sale on 3 and above. I would take the Denon amp section out of the equation and go with sepparates. I still don't understand why it is clipping...when you have tried running the center and surrounds in small? How long are your speaker wire runs to the rear and what guage wire are you using? Regarding the bass tone control....leave it flat or "o". When you hook up a sub...then you will only deal with the subwoofer output...leave the tone controls flat.

    Let us know what you decide....you have the makings of an awesome setup!
     

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