setting sub up correctly

[bobbyc]

hello all. i just bought a cerwin vega sub 150. this thing kicks ass. i want to set it up correctly w my receiver. I have the onkyo 705. i noticed on the sub there is no sub output. just speaker terminals on back. i want to get the most out of the sound of the sub, and have it working correctly w the receiver. any suggestions on how to get this properly configured. thanks

[Kevio]

You'll get the most out of the sub if you connect the sub output on the receiver to the line input on the sub. I gather that there is no line input on this sub. Curious. Please confirm and perhaps we can come up with some sort of plan B.

[Mr Peabody]

That's odd the sub wouldn't have line level inputs.

I'd recommend setting the receiver's setup menu to "no sub", so the low end goes to mains. If there are choices as to where you want the LFE to go, choose "mains". Then take the left/right front speaker terminals to sub and then from sub to fronts.

[audio amateur]

He said there's no sub out on the SUBWOOFER. Not the amp.
But why would you need a sub out on the sub?

[Mr Peabody]

Well there definitely is a sub out on the 705, and I've never heard of a sub out on a sub nor would I even imagine what it would be used for, so we're basically making assumptions on what he meant unless he comes back and corrects himself or clarifies.

[musicman1999]

My previous JM Labs sub had a sub out on it, it was used to chain multiple subs together. The LFE signal went in and was repeated out to the second sub. It just meant that if you had only one sub out and wanted to use 2 subs, you did not need to use a splitter. My current Labs sub does not have this feature however and i don't think they used it very long.

bill

[audio amateur]

Well there definitely is a sub out on the 705, and I've never heard of a sub out on a sub nor would I even imagine what it would be used for, so we're basically making assumptions on what he meant unless he comes back and corrects himself or clarifies.

That's why I assumed what he wrote was correct.

[bobbyc]

Hey guys thanks for responding, . there is no line out on this sub. i have my sub cable connected to one of the audio jacks(red). im getting sound out of the sub when im listening to music or watching movies. i just want to fine tune it. there is 2 sets of audio jacks and connections to speakers. there is no sub out. i have sub frequency set to 80 and did the same on my receiver

[markw]

Sounds like you're on the right track. IIRC, you have the receiver's sub out connected to a line input on the sub. That's good.

One suggestion : Leave the receiver's crossover as is but turn the sub's crossover to as high a setting as possible, or even "off" if that's an option. This will assure that your receiver controls that function, notthe subs. Two crossovers tend to not do too well.

[audio amateur]

Or better yet, if you can't turn it off on the sub, turn it off on the amp and use the sub's crossover.

[bobbyc]

ok ill do that. what crossover frequency should i set the sub to? its on 80 now, can go up to 120

[audio amateur]

Depends what type of speakers you have. The bigger the speakers the lower you will want to set the crossover. If they are big floor standing speakers I'd set them at the lowest possible setting. If they are small 'satellite' speakers, I'd set it around 100Hz.

[Mr Peabody]

Do as Markw said and turn the sub crossover all the way up unless you have a bypass switch, then use that to turn the crossover off. On movies the LFE is encoded on the disc so it would be better to let the receiver interpret that. If only using the sub for stereo music either crossover would work. But for multichannel it will be better to use the receiver's crossover as fronts and rears will have different crossover point needs.

The sub input you are using, is it labelled "LFE". If it isn't you could possibly increase the subs output by giving both inputs a signal with a Y adaptor. You used to always have to feed both inputs for best results but newer subs are starting to design them to where a single input does the same. If that's the case the sub is marked some how by one of the inputs.

[Kevio]

Or better yet, if you can't turn it off on the sub, turn it off on the amp and use the sub's crossover.

Why is this better?

[audio amateur]

Why is this better?

I'll remove what I said, it's only better if he can't by pass it on the sub and can on the amp. In which case i think it's better to use the subs xover.

[Kevio]

The sub's crossover is fundamentally limited because it cannot do anything for the mains. To do a correct crossover, you want a low pass on the sub and high pass the mains. Most home theater receivers will do both for you.

[audio amateur]

The sub's crossover is fundamentally limited because it cannot do anything for the mains. To do a correct crossover, you want a low pass on the sub and high pass the mains. Most home theater receivers will do both for you.

I can agree to some extent but personally I don't see the point of high passing unless you have very small speakers that are bass limited. And perhaps also if you're going to turn the volume up to ear bleeding levels.

[Kevio]

Filtering both the mains and the sub is the only way you can tightly control the response of the overall system. The shape of the natural rolloff of the mains is unlikely to dovetail nicely with the sub leaving either a bump or dip in the response. You'll generally not be able to correct this by twiddling the crossover frequency on the sub because both the shape and location of rolloff need to be matched. Only the location of the rolloff is adjustable on most subs. The receiver has high pass and low pass filters with pre-matched shape.