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

Jason Cheung · 10-25-2003, 04:06 AM

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

Marty Neudel · 10-25-2003, 07:42 AM

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

Chuck Kent · 10-25-2003, 09:20 AM

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!

Mark All · 10-25-2003, 11:01 AM

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.

Jason Cheung · 10-25-2003, 01:16 PM

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?

Quote:

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.)

Now, seeing that I'm not sure if the "Small" setting is really making a difference (since it's clipping already at this setting), would adding a sub still be a good, possible solution to this clipping problem?

Regardless, I am definitely going to get a sub anyways.

Chuck, what do you think about the Rotel RMB-1075, as suggested by Mark?

Mark, thanks for your input also!

Seeing that you have a 3803 I've got some questions for you concerning my problem.

I don't know much about the receiver, but wouldn't my using it only as a preamplifier/processor really be "using it for what I payed for?" If I went this route, that would mean I didn't really need the power from the receiver after all.

Seeing that I don't use the receiver for anything other than hometheare (I don't use multi-room, or connect hardly any other source things into it), should I consider flipping it and looking at a stand alone preamplifier/processor? Or, is the 3803's processing capabilities so good, that I should just keep it and add another amp, like the Rotel 1075. (By the way, do you have the 1075? How much does it cost? Can I get it used somewhere?)

Well, thanks to you all for your help. I should let you know, that for a beginner like me, your help is absolutely indispensable!

Thanks! And I will be sure to update you on how my "problem" is faring after awhile.

Cheers,
Jason

**HTF Ads**

Chuck Kent · 10-25-2003, 09:55 PM

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...

Mark All · 10-26-2003, 01:27 AM

Quote:

Seeing that I don't use the receiver for anything other than hometheare (I don't use multi-room, or connect hardly any other source things into it), should I consider flipping it and looking at a stand alone preamplifier/processor? Or, is the 3803's processing capabilities so good, that I should just keep it and add another amp, like the Rotel 1075. (By the way, do you have the 1075? How much does it cost? Can I get it used somewhere?)

Jason,
You may want to consider a pre/pro but the 3803 is actually a very good cost-effective product to use as a pre/pro. It is also very effective used by itself without a separate amplifier for those who have 8 ohm speakers and send LFE to a subwoofer. Except for the Outlaw pre/pro, entry level pre/pros cost considerably more than the 3803 for what I considered to be inferior features and connectivity when I got mine late last year. I bought a 3803 and a Rotel RMB-1075 with the intent of eventually getting a dedicated pre/pro but haven't found the need to do so. The lack of availability of reasonably priced home theater processors is a problem with the market. One would think that Denon, Sony, Pioneer, etc, would be able to manufacture and market an excellent dedicated pre/pro for home theater use for under $1000. As it is, we're stuck with good pre/pro sections in a lot of mass-market receivers that are hampered by weak amplifiers.

The MSRP on the Rotel RMB-1075 is around $1000. There's usually at least one used amp for sale on audiogon Web site (www.audiogon.com). You may be able to get a discount of 5 to 10 percent from an authorized dealer, but I wouldn't expect much more than that. There are lots of other 5 channel amps available now, but the Rotel is one of the best at its price point.

CurtisC · 10-26-2003, 06:27 AM

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.

Chuck Kent · 10-26-2003, 08:26 AM

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

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.

(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...

Mike Sloan · 10-26-2003, 12:28 PM

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!!!!!!!!!!!!

keir · 10-26-2003, 03:49 PM

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 o