LFE ??????? Sub???? RM7600

BigBoneDee

Hello all. Been reading and reading and sometimes I get it and sometimes I end up exhausted. However I want to thank all those people in advance for their patience and for sharing their knowledge with us newbies.

My question is regards to my system:

Receiver RX -v1300
Speakers RM7600
Sub PSW 404

Honestly I paid for this thing to be hooked up . The tech tried his best to diagram all I needed to do so I could do it myself but I could just see the wife standing over me telling me to hurry it up.

My first question is this; My receivers LFE is set to 90hz. It has been recommended here that I set it to 150 hz because my Rm 7600 go to 150hz. Thats all good but when I look at my receivers manual for LFE level it says that it is preset to o db but can be set from -20 to 0. My question is wether or not I am at the right section because I dont see any mention of HZ or amybe its just that I have to convert DB to HZ in my head and if thats the case then what is 150hz in db?

My second question is this: The tech who set up ran one sub cable from the subout on receiver to the R and L input on back of the sub via a Y. I also see that there is an LFE input option (just one hole) that could have been used instead. What is the difference in the two options R and L input and LFE input options? Also that I have chosen to use the R and L input option on the back of the Sub will low pass knob on back of the sub be functional or where should it be set from 60 to 125. Additionally where should the phase switch bet set to on back of the sub :0 or 180 and what is the purpose of this switch?

I know I have asked alot and thank you in advance.

Dr. Spec

You're confusing the LFE channel level with the subwoofer channel level with the subwoofer crossover frequency.

Leave the LFE channel level set to 0 dB.

First, determine if your receiver can alter the subwoofer crossover frequency in Hz. Some AVRs are fixed at 80 or 100, but some can be varied.

Regardless, I highly doubt your AVR can go up to 150 Hz, which is apparently where you need to be for your sats.

If your AVR can't go to 150 Hz on the sub crossover, here's what I recommend:

Set all the speakers to small except the mains.

Set the mains to large.

Set the subwoofer to off/no.

Run speaker wire from the AVR to the L/R inputs on the 404.

Set the 404 crossover to 150 Hz.

Run speaker wires from the 404 outputs back to the L/R mains.

Calibrate all the speakers with your test tones to 75 dB and calibrate the 404 to about 78 dB. Use a sound pressure meter for this from Radio Shack for $40. Use C-Weighted Slow for your readings and take them at the listening position.

Doc

BigBoneDee

Doc many thanks. I wonder though what the audible difference really is between your recommendation and just having all the speakers wired to the receiver.

I sure would hate to think that I spent 70 bucks on a sub cable that I am not going to use now.

Well I guess I will have to try and see but before I do I would sure like to know what differences I should expect to see in both setups.

Dr. Spec

Originally posted by BigBoneDee
Doc many thanks. I wonder though what the audible difference really is between your recommendation and just having all the speakers wired to the receiver.

I sure would hate to think that I spent 70 bucks on a sub cable that I am not going to use now.

Well I guess I will have to try and see but before I do I would sure like to know what differences I should expect to see in both setups.

Let's assume your AVR can only go up to 80-100 Hz on the sub crossover using the sub cable method.

If your sats can only extend down to 150 Hz before they roll-off and/or are internally filtered, then you can expect a large hole or depression in the frequency response between 150 Hz and 80-100 Hz.

That's because the sub isn't playing high enough, and the sats aren't playing low enough. The speaker level connection fixes that.

I prefer the sub cable connection method for several reasons, but all your surround speakers should be capable of extending down to 50-60 Hz if you use this method.

That means going with larger speaks all around, or eating the $70 sub cable, or living with a hole in the FR between 80 and 150 Hz.

Try both methods and see which sounds better to you.

Doc

fireshoes

A 150 hz crossover setting seems kinda high form the RM7600 system. I haven't been able to find the specs for the speakers themselves, but would be surprised if they don't play much lower than that.

section19

Originally posted by BigBoneDee
It has been recommended here that I set it to 150 hz because my Rm 7600 go to 150hz.

There was some information posted here recently about RM 6700's having an internal crossover of 150 Hz. But they have quite a bit smaller drivers than the 7600's. It's hard to know what the sats are rated at since Polk likes to include the sub in its freq. ratings with it's sub/sat packages.

You might want to call Polk customer service and see what they say the surrounds themselves are rated. My guess is they will strongly recommend you run your mains through the sub (mains set to large, sub set to off) as Doc suggested.

Welcome. I'm new here myself, but this seems like a very cool place. You'll get lots of great info here. All you have to do is ask.

Dr. Spec

Best to ask Ken S. if the 7600 sats are internally filtered and if so at what frequency.

If they are not filtered, ask him what the - 3dB bass extension frequency is for the sats.

The RX-V1300 has a fixed 90 Hz crossover to the subwoofer, more than likely at a 12 dB/octave slope. That would require the sats to play down to around 70 Hz.

Doc

BigBoneDee

Well Dr. Spec I started to wonder what your tech consultation would probably cost me without the uses of the internet and having you come to my house and explain the advice youve given me in person and I said to myself,"Hey stupid you asked for advice and you got it . Now what?"

So off to the hifi store I went for some monster speaker wire and after wiring and setting everything as you suggested I cranked it all up demoed the the fight scenes of the movie Gladiator, especially liked the tiger scene. The roar was so real . No Boominess at all and yet the speakers seemed to all come alive with a a seemless match of high mids and lows. The sub thanks you. Its alive now even at the 12 oclock volume setting.

Musically I demoed jazz, pop and ofcourse Pavorotti. Pavorotti will really uncover the limitations of any speaker. The sats strained a bit at the very highs but hey they held their own and they are small after all.

Dr. Spec many thanks and salutations:)

Now if anyone has any suggestions on a rear center channel , well let me know.

Dr. Spec

Glad you are loving the sound. I still think finding out the exact best crossover from Polk is a good idea and you might find it is around 120 Hz instead of 150 Hz.

Lowering the crossover a bit (per Polk's specific recommendation)will help reduce subwoofer localization and also will reduce chestiness and a disembodied flavor on deep male voices.

Doc

BigBoneDee

Well I had checked the back of the sub and found that sub crossover dial settiing will only go to 125 and thats what I put it on.

The sound is pretty incredible. I kept getting up and putting my ear to the sats thinking that the bass was coming out of them when in fact its just that the range in the high and mids in the sats and the bass coming out of the sub are so seemless that all the sound and bass appears to be coming from the sats when in fact its not. You would never be able to localize the sub in the room just by listening . Its not to the left or right or back or front but the bass just exists.

I am not quite sure if this was supposed to happen Dr. Spec but the sound from the sats improved quite a bit by wiring as you suggested.

Dr. Spec

Originally posted by BigBoneDee
Well I had checked the back of the sub and found that sub crossover dial settiing will only go to 125 and thats what I put it on.

I am not quite sure if this was supposed to happen Dr. Spec but the sound from the sats improved quite a bit by wiring as you suggested.

Well, 125 is probably high enough, and it's the best the 404 can do anyway.

Naturally it sounds better because the hole between 90 and 125 has been filled in whereas before there was a hole in the frequency response because your sats either naturally don't play that low and/or have a filter in them that artificially limits bass response.

You are good to go. If you ever switch to larger speaks all around, you can go back to the sub cable method.

Doc

BigBoneDee

Thanks Doc for all the help. However if I ever go to larger speakers it will be the motel cause my wife aint having it.