View Full Version : To LFE or Not, That is the question
06-11-2002, 11:41 AM
Dear Kenneth S.,
I have a set of RM6600's and a PSW650. With my old receiver I hooked up the sub like you guy's suggested, sounded good. Now I have a new receiver that lets me do a whole bunch of things. (most of which I don't understand). First off the the TV (Sony WEGA) is in a corner (wife says that's where it goes), so I put the sub in another corner. Seems to me to be a good location for it. Some time back someone said how to tell if my LFE is filtered or not (Can't find it in the owners manual) but I can't remember how. Also Kenneth, I think you had told someone a while back that if the receiver would allow the cutoff Mhz to be adjusted to hook the sub up through the LFE and set all the speakers to small. (Makes sense). The part I don't remember is what to set the crossover (or whatever it's called) too. 150 keeps coming up in my mind but that seems too high. Seems like most of everything would be going to the sub. Anyway whatever help you guy's can offer would be great.
06-12-2002, 04:39 PM
Thanks for participating in the Forum. The goal is to allow the PSW650 to reproduce sound up to 150 Hz, because the satellite speakers go down, in frequency, to around this limit. You can accomplish this in one of two ways, first, some receivers have an adjustable low pass filter as part of their sub out connection. Some of the Sony receivers allow the owner to select from 80 to 200 Hz as a low pass filter point. If yours does this (and it should be covered in their owner's manual) set the filter point to 150 Hz (this is assuming you have your front satellites placed at ear level on a wall) and use a single shielded RCA cable from the receiver's sub out to the LFE input on the PSW650.
If the receiver company doesn't mention the cutoff frequency of its sub out, assume it is probably 80 or 90 Hz. This is too low, any sub-woofer connected to this output is only going to play up to this frequency which is going to result in a gap in the mid bass frequency range. This takes away a feeling of "heft" and "weight" in the way bass sounds, bass information may begin at 30 or 35 Hz, but it will have complex harmonic overtones which need to be reproduced in the original proportion. If the fundamental sound is at 35 Hz the first even harmonic is 70 Hz and the second is at 140 Hz and if your system isn't reproducing the 140 Hz sound with the same strength as the "neighboring" frequencies it isn't going to sound correct.
So, instead of the sub-out connection, if your receiver has true pre-amp right and left main outputs, you could use a right and left RCA cable from the receiver's pre-amp outputs to the corresponding right and left line level inputs on the PSW650. Then adjust the variable low pass filter (on the PSW650) to 150 Hz. You have shifted the job of shaping the filtering from the receiver to the sub-woofer, allowing it to determine the upper frequency contribution to the blending.
If your receiver doesn't have pre-amp outputs, the next best connection method would be a simple right and left speaker level out to the right and left speaker level inputs, here again, adjust the low pass filter to 150 Hz. Remember the goal is to allow the sub-woofer to be able to play up to 150 Hz and this only applies to small RM series satellite speaker systems.
06-12-2002, 05:40 PM
would you recomend this set up for the RM7600 series also??
I am currently running it through the speaker level. I have a lfe cable hooked up to my reveiver but have not had the time to mess with all the different possible settings the 3802 offers. You also recomended setting the 650 to 150 Hz. I didn't think that the 650 goes that high. I keep mine around 90, any higher than that and it sounds like mud.
06-13-2002, 08:18 AM
Yes my receiver lets me adjust the LFE from 80-150. The front speakers wont be at ear level but at the top of the wall angled down. Will that cause a problem?
06-13-2002, 08:24 AM
Does anyone know where I can get a sub cable 32 feet long?I'm haveing to follow my wife's constants on where the speakers go and no wires showing.
06-13-2002, 11:19 AM
Hello Mark and Lakeray,
The RM7600 requires a little bit of experimentation to determine what might be the best connection method. Mostly it has to do with the receiver that's powering everything. If the receiver permits sending front right and left bass information along with the ".1" channel LFE information to the sub out, then a single RCA connection from the receiver's sub out to the LFE input, on the PSW650, would be fine. The crux of the dilemma is in most receivers unless a channel is described as "small" the bass information, of that channel, will not be fed to the sub-out. But, with smaller speakers, when you describe their channel as "small" this will introduce a high pass filter into a speaker that already has a built-in high pass filter and you will have double filtering. As I write this, I'm feeling that I'm causing more confusion and certainly don't want to do that. But, there isn't a clear cut single answer to every receiver's possible combination. However, if you want to cover all bases, with the PSW650, you could run a right and left speaker level signal from the receiver's front channel outputs to the speaker level inputs on the sub-woofer and an RCA cable from the receiver's sub out to the LFE input on the sub-woofer. This would provide right and left bass information from the sub-woofer as well as LFE information for 5.1. Keep in mind, this applies to just the PSW650 because of it's unique connection capabilities.
For owners of RM6600, RM6200, RM7200 and RM6000 combined with any other sub-woofer use the speaker level method, avoid the problem by providing full range information to the sub-woofer so it can reproduce sound to the necessary 150 Hz cutoff frequency. But, wall mounted RM7600 (RM7500 also) can produce lower frequencies and change the way the sub-woofer needs to produce bass information, it doesn't have to reproduce as high a frequency and the PSW650 offers some connection possibilities because of its isolated input connections. You are correct, the upper setting on the PSW650 is 120 Hz, not 150 as I previously stated.
There is a company called Phantone that makes a 25' and a 50' shielded RCA cable, most audio shops are familiar with this company. You can also use RG59 shielded coaxial cable (available at most electronic parts stores and Radio Shack) as a connecting cable, however you will have to attach RCA plugs at both ends.
I hope this is helpful information.
Take care, Ken
06-13-2002, 01:22 PM
"However, if you want to cover all bases, with the PSW650, you could run a right and left speaker level signal from the receiver's front channel outputs to the speaker level inputs on the sub-woofer and an RCA cable from the receiver's sub out to the LFE input on the sub-woofer. This would provide right and left bass information from the sub-woofer as well as LFE information for 5.1. Keep in mind, this applies to just the PSW650 because of it's unique connection capabilities. "
I am running R & L pre-outs and sub-preout from the Denon 3801 to the PSW650. By doing this, in theory, I can adjust the sub x-over frequency (mains) on the sub vs. being stuck at 80HZ with the Denon. I think better blending is accomplished this way.
I am using the PSW650 to supplement the 3.1TL's lower end in music. I don't like the idea of running speaker level through the sub becuase I want a full (non-hi-pass-filtered) signal going straight to the 3.1TL's. I don't want to turn the sub off on the Denon (as the manual suggests)... because, I prefer the U571 explosions going only to the PSW650 (not the 3.1TL's).
Does this make any sense to you? Do you agree with my rationale? Please advise.
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