NAD T743 receiver sub channel clipping - need upgrade?

[Blueeyedfrog]

Hi everyone,

I am finding that my current NAD T743 receiver is clipping (with BFD LED) in the subwoofer channel and so I have to set it at around -8 to -10db compared with the rest of the speaker channels which are set around 0db. I'm happy with the volume output of the mains when I crank the receiver up to 0db but I have to keep the overall gain down around -8db or the subwoofer starts clipping.

So I need a new amp right? The receiver doesn't have enough oomph to deliver the sub channel, compared to the other channels? I was thinking the next size up NAD receiver?

Cheers,
Blue

[Wayne A. Pflughaupt]

Okay, I’m confused. If it’s your sub that’s clipping, why would you need a new receiver? Sounds like a better sub is what you need.

Regards,
Wayne

[Mike P.]

Hi Sam, is this the same sub amp you were using with the Peerless subwoofer?

[Blueeyedfrog]

It's the same sub amp that I am using with the Peerless - a 240 watt plate amp, but in a few months I'll be upgrading to something like an EP2500. But in preparation for my new sub set-up (and two Mach 5 Audio IXL-18s), I'm thinking that I'll need a beefier amp to feed the new sub amp?

I think I need a new amp because my amp is clipping - ie. the signal is clipping before it reaches the sub amp... which I presume will limit the output of the sub? At present I am able to prevent the sub from clipping by reducing the receiver output - but wouldn't it be better to be able to output a louder signal from the receiver that doesn't clip (similar to the output to the main speakers)? And so that's what makes me think I need a new amp (more headroom?)... Yes/no?

[Mike P.]

I'd say your Peerless sub/amp combination is simply maxed out. Since you will be getting a EP2500 soon, wait and see if that is the problem. No sense buying a new receiver if it's not the issue.

[Wayne A. Pflughaupt]

- ie. the signal is clipping before it reaches the sub amp...

How did you determine that?

Regards,
Wayne

[Blueeyedfrog]

Well, I think my receiver is clipping because my BFD input LEDs are going into the red - when they are up there my sub starts to make poping noises (unless I turn my sub amp down) - so that means my receiver is clipping, right ?

I see your point Mike re waiting to see how the new sub system performs...

[Wayne A. Pflughaupt]

Blueeyedfrog wrote:

Well, I think my receiver is clipping because my BFD input LEDs are going into the red - when they are up there my sub starts to make poping noises (unless I turn my sub amp down) - so that means my receiver is clipping, right ?

Nope. It means your feeding too much signal from the receiver to the BFD. Reduce the sub output in the receiver (hopefully that’s an option) to where the LEDs only hit the yellow occasionally; that will give you some headroom. Naturally, this will mean your sub will have to be turned up (using its gain control).

Note that this isn’t probably going to fix the problem with your sub. You see, low frequency distortion has to get much higher before it’s audible than mid-to-upper frequency distortion. So even if the BFD is clipping, it probably wouldn’t be audible. Popping noises from the sub usually means the driver is bottoming out, or perhaps that the amp is clipping. Equalization places additional demands on the amp and driver, so going in you have enough reserve in headroom to handle it.

Regards,
Wayne

[Blueeyedfrog]

So I don't need a new receiver then? Everything will change when I get the new EP2500 / Mach 5 18"s - so wait until I run the new sub setup then, as Mike suggests?

By the way, could that mean my mains are clipping if my sub channel is feeding too much to the sub?

[Wayne A. Pflughaupt]

One has nothing to do with the other.

Regards,
Wayne

[Mike P.]

Your going from a 12 inch Peerless/250 watt plate amp to an EP2500 / twin Mach 5 18 sonotubes. Are you ever in for a nice surprise! Make sure you keep us posted!