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Subwoofer Connection Advice

post #1 of 9
Thread Starter 

Right now, I have in my possession the Emotive mini-x a-100, which I already have an RMA number for because I was planning on sending it back.

 

The reason I was planning on sending it back is because of my subwoofer setup. The only place in my room that the subwoofer sounds good in is the far back corner, and I have a home made RCA cable running around the edge of the room and around the door and under the bed to get to the subwoofer.

 

I currently have my studio monitors and subwoofer hooked up to an onkyo HT-R540 receiver, and am using the software in the receiver to send the bass to only the sub via LFE and the rest to the speakers. The crossover is at 60hz.

 

I was wondering if it would be advisable to get a higher quality sound card with rca output, put that into the emotiva amp, split the speaker output on the emotiva amp, and use the rca to carry line level to the sub. I could get a female RCA plug for each end of the LFE cable, which I would solder two wires to and leave them bare at the other end for plugging into high level outputs on the emotiva amp, and high level inputs on the sub.

 

The downsides to this would be that i would not have a high pass filter on the speakers, only a low pass filter on the sub, and also that the RCA cable consists of a center conductor with a thick shield around it, grounded on both ends. I am not sure how high level would sound going through a wire like this. would the negative lead being the shield and the positive lead being the center make them interact electromagnetically?

 

what do you guys think? The main problem in my opinion is the high pass filter on the studio monitors. I do not want to introduce distortion to the mids by making the speakers play the bass notes which they are not rated to produce below 40hz or something like that.

post #2 of 9
The short answer is do not do what you're proposing.

The long answer is that what you're proposing is dangerous to the amplifier and subwoofer, and will be a performance downgrade from the AV receiver.

Leave things as they are now with proper bass management.
post #3 of 9
Thread Starter 

it is not dangerous to the sub, and the only reason it would be dangerous to the amp would be if the impedance of the high level inputs on the back of the sub are low. my speakers are already a low 4 ohms, any lower and any amp will run hard. I think either you misunderstood what i was proposing, which is simply to use the RCA cable as speaker wire, not to put high level output into the LFE in on the subwoofer, or i did a poor job of explaining.

 

On the other hand, "Use proper bass management" was the answer i was expecting. I just really want something more compact, and doesnt have a bunch of features i dont need. All i use in my receiver is the DAC, two of the amp channels, and the adjustable LFE output. 

 

Thank you for your reply.

 

Does anyone know of a slightly-more-compact-than-a-receiver stereo amplifier with subwoofer output?

 

would i be better off going with a preamp that has subwoofer out and active studio monitors?

post #4 of 9

You definitely could get a better sound card with RCA out, split the RCAs, and then configure a mini-DSP with the Emotiva amp to act as a high pass filter. Don't know how well it works for that. Mainly I've just heard of people using those with DIY subs for their EQ capability and to add a filter at the low end. Or you could try an FMOD high pass filter in line there between the amp and the sound card. I've heard mixed reviews about how well they work. 

 

Marantz has lower profile receivers (not lower footprint): for example, Marantz NR1402. It has Audyssey MultiEQ, which is really helpful for improving sub response in a room. 

post #5 of 9
Thread Starter 
Quote:
Originally Posted by cel4145 View Post

You definitely could get a better sound card with RCA out, split the RCAs, and then configure a mini-DSP with the Emotiva amp to act as a high pass filter. Don't know how well it works for that. Mainly I've just heard of people using those with DIY subs for their EQ capability and to add a filter at the low end. Or you could try an FMOD high pass filter in line there between the amp and the sound card. I've heard mixed reviews about how well they work. 

thats a really cool idea, i hadnt thought of that. after some consideration, though, i think i want adjustable, active crossovers.
Quote:
Originally Posted by cel4145 View Post

Marantz has lower profile receivers (not lower footprint): for example, Marantz NR1402. It has Audyssey MultiEQ, which is really helpful for improving sub response in a room. 

looks like the only model that is designed specifically for 2.1 setups without video is the SR4023. If i cant find anything smaller (i have a place lined up for either something with the same footprint but shorter, or something half the width with any height.) it might be worth it for me to just spend my time any money in the meantime modifying my desk or making a new one with a built in equipment rack. It looks like my options are much better if i just give in and accommodate the standard size receiver.
post #6 of 9

Look into the mini-dsp then. It has PEQ built with choice of the type of high pass filter you want to use. I read up on it a little a while back when I was thinking of doing a DIY subwoofer, and it's a nifty device just to read about. There's even a plugin for it so you can use REW coupled with a condensor mic to take in room measurements, and then REW will apparently set the PEQs to flatten the speaker output. 

post #7 of 9
Thread Starter 

wow that thing is really, really cool.

post #8 of 9

Yeah, for $99, it's really impressive. Linkwitz-Riley 4th order filters would be awesome for creating a smooth crossover point between the sub and the speakers. I so want one, but I don't really need it biggrin.gif

 

Did you see this stereo graphic eq plugin addon for $10? "two 31 bands equalizers, low and high pass filter , per channel delay (up to 7.5ms) and gain adjustments." Look at the data sheet and see the diagram at the bottom of the first page. That plugin would give you way more fine-grained control than an HT receiver, as long as your subwoofer has left and right channel inputs. 

post #9 of 9
Quote:
Originally Posted by Skoobs View Post

it is not dangerous to the sub, and the only reason it would be dangerous to the amp would be if the impedance of the high level inputs on the back of the sub are low. my speakers are already a low 4 ohms, any lower and any amp will run hard. I think either you misunderstood what i was proposing, which is simply to use the RCA cable as speaker wire, not to put high level output into the LFE in on the subwoofer, or i did a poor job of explaining.

You're talking about taking a two conductor RCA/coax lead and running four conductor signals over it, which will bridge -VE (and short the L/R hot terminals); which is dangerous to both sides. You would need a four conductor lead to do this appropriately.
Quote:
On the other hand, "Use proper bass management" was the answer i was expecting. I just really want something more compact, and doesnt have a bunch of features i dont need. All i use in my receiver is the DAC, two of the amp channels, and the adjustable LFE output. 

Thank you for your reply.

Does anyone know of a slightly-more-compact-than-a-receiver stereo amplifier with subwoofer output?

would i be better off going with a preamp that has subwoofer out and active studio monitors?

If you want to purchase something new and smaller, cel's suggestion of the Marantz receiver is a good one. But the whole "I want to pay more to get rid of features I don't use" thing has never made sense to me. redface.gif
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